# D1.1 Report on the Benchmark of High Temperature Oxidation Resistant Materials and Thermo-Mechanical Test Campaign

Sébastien Chomette, Marianne Balat-Pichelin

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Sébastien Chomette, Marianne Balat-Pichelin. D1.1 Report on the Benchmark of High Temperature Oxidation Resistant Materials and Thermo-Mechanical Test Campaign. [Research Report] European Union. 2020. hal-04750960

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POLYPHEM
THE FUTURE OF SMALL-SCALE CSP PLANTS

POLYPHEM
Small-Scale Solar Thermal Combined Cycle

# D1.1 Report on the benchmark of high temperature oxidation resistant materials and thermo-mechanical test campaign

Date of delivery 25/04/2020

Authors Sébastien CHOMETTE, Marianne BALAT-PICHELIN

Institution/Company CEA, PROMES-CNRS

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This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 764048.
## Document tracks

<table><tr><td>Identification</td><td>POLYPHEM_WP01_D1.1_19-152</td></tr><tr><td>Title</td><td>Report on the benchmark of high temperature oxidation resistant materials and thermo-mechanical test campaign</td></tr><tr><td>Authors</td><td>Sébastien CHOMETTE, Marianne BALAT-PICHELIN</td></tr><tr><td>Reviewers</td><td>Alain FERRIERE, Simon SCHÜTRUMPF, Peter SCHÖTTL, Juan Manuel CARUNCHO RODADO</td></tr><tr><td>Related Work Package (s)</td><td>WP01: R&D ON SOLAR RECEIVER</td></tr><tr><td>Beneficiary responsible of delivery</td><td>CEA</td></tr><tr><td>Due date of delivery</td><td>30/09/2019</td></tr><tr><td>Submission of 1st version (uncomplete)</td><td>18/11/2019</td></tr><tr><td>Submission of final version (complete)</td><td>25/04/2020</td></tr><tr><td>Number of pages</td><td>81</td></tr><tr><td>SUMMARY</td><td>This document is the deliverable D1.1 of the project POLYPHEM. It is planned in the framework of the Work Package 01 (R&D ON SOLAR RECEIVER).<br/>Task 1.1 of the POLYPHEM project deals firstly with the choice of a more competitive metallic alloy than the reference one, the alloy 600, in order to manufacture the solar receiver modules, more precisely, the environment protective layer. Secondly, the mechanical properties and microstructure of the best alloy and the reference one are examined using representative mock-ups.<br/>This deliverable presents the main results of the POLYPHEM Task 1.1.</td></tr><tr><td>Dissemination level</td><td>PU</td></tr><tr><td>Repository</td><td>https://dms.polyphem-project.eu</td></tr></table>

## Document History and Validation

<table><thead><tr><td>Date</td><td>Name</td><td>Comments</td></tr></thead><tbody><tr><td>31/03/2020</td><td>Sébastien CHOMETTE</td><td>Creation</td></tr><tr><td>16/04/2020</td><td>Simon SCHUTRUMPF</td><td>Review 1</td></tr><tr><td>17/04/2020</td><td>Alain FERRIERE</td><td>Review 2</td></tr><tr><td>24/04/2020</td><td>Sébastien CHOMETTE, Marianne BALAT-PICHELIN</td><td>Final version</td></tr></tbody></table>

All information in this document only reflects the author's view. The European Commission is not responsible for any use that may be made of the information it contains.
## Background: about the POLYPHEM project

<table><tr><td>FULL TITLE</td><td>SMALL-SCALE SOLAR THERMAL COMBINED-CYCLE</td></tr><tr><td>Acronym</td><td>POLYPHEM</td></tr><tr><td>Call identifier</td><td>H2020 LCE-07-2017-RES-RIA-TwoStage</td></tr><tr><td>Instrument</td><td>Research and Innovation Action (RIA)</td></tr><tr><td>Grant Agreement N°</td><td>764048</td></tr><tr><td>Starting Date</td><td>01/04/2018</td></tr><tr><td>Duration</td><td>48 months</td></tr><tr><td>Website</td><td>https://www.polyphem-project.eu</td></tr><tr><td>Keywords</td><td>Renewable electricity; Energy collection, conversion and storage; Renewable energy</td></tr><tr><td>Additional keywords</td><td>Concentrated solar power; Solar tower system; Combined cycle; Gas-turbine; Thermal energy storage; Organic Rankine cycle; Process control</td></tr><tr><td>Beneficiaries</td><td>CNRS, CEA, CIEMAT, Arraela S.L., Fraunhofer ISE, KAEFER Isoliertechnik, Orcan Energy, Euronovia, Aalborg CSP</td></tr></table>

The POLYPHEM project is a research and innovation action funded by the European Union's H2020 program. It is implemented by a European consortium of 4 research centers and 5 industrial partners. The aim is to increase the flexibility and improve the performance of small solar tower power plants. The concept of POLYPHEM consists in implementing a combined cycle formed by a solarized micro gas-turbine and a Rankine organic cycle machine, with an integrated thermal storage device between the two cycles. The need for cooling is minimal.

Developed from a patented technology by CNRS and CEA, the pressurized air solar receiver is integrated in the micro-turbine cycle. The thermal efficiency targeted for the receiver is 80% with a cost of 400 €/kW. The innovative thermal storage uses a thermal oil and a single thermocline tank with a technical concrete filler material.

The main expected impact of this project is to enhance the competitiveness of low-carbon energy production systems through the technology developed. The expected progress is a better fitting of electricity generation to variable local needs, an overall conversion efficiency of solar energy into electricity of 18% for an investment cost of less than 5 €/W and a low environmental impact. By 2030, the cost of electricity production targeted by the POLYPHEM technology is 165 €/MWh for an annual direct normal irradiation of 2600 kWh/m²/year (North Africa and Middle East) and 209 €/MWh under 2050 kWh/m²/year (Southern Europe). In addition to decentralized power generation, other applications are considered for the deployment of this technology used in poly-generation: industrial heat production, solar heating and cooling, desalination of seawater or brackish water.

A prototype plant of 60 kWel with a thermal storage of 1300 kWh is designed, built and installed on the site of the experimental solar tower of Themis in Targasonne (France). The objective of the project is to validate the technical choices under test conditions representative of actual operating conditions.

This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 764048
## Table of content

1. Introduction 10

2. Benchmark of high temperature oxidation resistant alloys 10

2.1 Literature results on solar receivers material selection 10

2.2 Alloys selection for solar receiver material benchmark 11

2.3 Alloys comparison 12

3. Characterization HIP mock-ups manufacturing 27

3.1 Mock-up designs 27

3.2 Material supply 30

3.3 Mock-up manufacturing 30

4. Microstructural characterization 34

4.1 Sample preparation and experimental procedure 34

4.2 Alloy surface treatment explanation 34

4.3 As received materials 35

4.4 HIP treated materials 38

4.5 Conclusions on microstructural characterization 44

5. Mechanical characterization 45

5.1 Research design 45

5.2 Experimental procedure 46

5.3 Mechanical tests results 46

5.4 Conclusions on microstructural and mechanical characterizations 61

5.5 Solutions to enhance Ni-based alloy interfaces after HIP process 62

6. Conclusions on solar receiver material investigation 63

## List of Figures

Figure 1: Comparison of alloys high temperature oxidation and nitridation performance 12

Figure 2: Comparison of alloys thermal conductivity and thermal expansion 13

Figure 3: Comparison of alloys high temperature tensile properties (Yield strength at 0.2% offset and elongation) 13

Figure 4: Comparison of alloys fatigue properties (number of cycles to rupture at room temperature) 14

Figure 5: Comparison of alloys creep properties (stress to obtain 1% creep after 100h, 1000h and 10000h) 15

Figure 6: HIP compatibility of benchmark alloys depending on their chemical composition 15

Figure 7: Comparison of plate cost 16

Figure 8: Result of the benchmark of selected alloys 18

Figure 9: 1MW solar furnace of the CNRS at Odeillo: (a) photography of the whole installation, (b) schematic representation of the solar furnace. 19

Figure 10: MEDIASE facility: (a) photography of the apparatus, (b) schematic representation. 20

Figure 11: Total hemispherical emissivity at high temperature under high vacuum. 20

Figure 12: Surface evolution between as received samples and after HT vacuum tests for alloy X and alloy 230 samples with Sq roughness parameter evaluation (Root mean square height, areal extension). 21

Figure 13: Directional emissivity during in situ oxidation tests in MEDIASE facility – Example of alloy HR-120. 21

Figure 14: Total hemispherical emissivity ε in the wavelength range of 1.4 – 14 µm (full dots) and “solar absorptivity” α in the wavelength range of 1.4 – 2.8 µm (open dots) versus temperature and table of ratios α/ε for alloys 600, X, 230 and HR-120. 22

Figure 15: Evolution of oxidized surface after HT exposure (SEM images). 22
Figure 16: Total hemispherical emissivity $\epsilon$ in the wavelength range of 1.4 – 14 µm (full dots) and “solar absorptivity” $\alpha$ in the wavelength range of 1.4 – 2.8 µm (open dots) versus temperature, table of ratios $\alpha/\epsilon$ and surface evolution after HT exposure (SEM images) for alloy 617. 23

Figure 17: Spectral hemispherical emissivity in the wavelength range 0.25 – 25 µm for the virgin samples at room temperature 24

Figure 18: Spectral hemispherical emissivity in the wavelength range 0.25 – 25 µm at room temperature for the samples oxidized at: (a) 1200 K during 24 h in air, (b) 1400 K during 24 h in air. 24

Figure 19: Samples after oxidation test during 24h at 1400K and sample prints on the furnace holder. 25

Figure 20: Evolution of the temperature and solar flux versus time during the oxidation test in air at 1200 K of the HEATEK® ROX sample. 26

Figure 21: Pictures taken during oxidation in air for samples HEATEK_2 at 1200 K (a) and HEATEK_3 at 1400 K (b) and picture of the optical fluorine window (c). 26

Figure 22: Schematic representations of solicited diffusion bonding junctions between Ni-based alloy parts in solar receiver. 27

Figure 23: Mechanical characterization mock-up concepts. 28

Figure 24: Description of HIP junction mock-up types corresponding to mechanical testing sample types. 29

Figure 25: Tensile samples extraction from mock-ups 600-A, 600-O, 230-A and 230-O. 29

Figure 26: Example of HIP mock-up machined parts after cleaning procedure. 31

Figure 27: HIP mock-up canisters. 31

Figure 28: Example of mock-up part cleaning. 32

Figure 29: Example of mock-up assembly (types 3 and 4): (a) all mock up parts, tools and canister, (b) first step of the manufacturing (bottom tools + centre part), (c) set up of three vertical plates, (d) set up of the three other parts, (e) cover placed on the finalized mock-up. 32

Figure 30: Tightening test example and degassing mock-up step. 33

Figure 31: Interface and base material mock-ups after the HIP step (alloy 600 and alloy 230, mock-ups 600-O and 230-O not presented). 33

Figure 32: Direct junction mock-ups between Ni-based plates (alloy 600 of alloy 230). 34

Figure 33: Direct junction between Ni-based plates SEM observations and chemical analysis (EDS) 35

Figure 34: Schematic representation of the plates showing the important direction for the microstructural observations 35

Figure 35: Microstructure of alloy 600 as received plates (OM). 35

Figure 36: Histograms presenting the fraction in number of grains and the surface fraction of the grains in the case of the as-received alloy 600 plates. 36

Figure 37: Microstructure of alloy 230 as-received plates (OM). 36

Figure 38: Histograms presenting the fraction in number of grains and the surface fraction of the grains in the case of the as-received alloy 230 plates. 37

Figure 39: Schematic representation of the extraction of the samples for coating thickness measurement. 37

Figure 40: Coating thickness measurement of the thick plates (intermediate mock-up block) and the thin plates (vertical mock-up plates) for alloys 600 and 230 (SEM). 38

Figure 41: Microstructure (OM) of alloy 600 parts after HIP process. 38

Figure 42: Histograms presenting the fraction in number of grains and the surface fraction of the grains in the case of the alloy 600 plates after HIP process in the small grain zones. 39

Figure 43: Microstructure (OM) of alloy 230 parts after HIP process. 39

Figure 44: Histograms presenting the fraction in number of grains and the surface fraction of the grains in the case of the alloy 230 plates after HIP process. 40

Figure 45: Schematic representations of the observed interfaces: // interface between two vertical thin plates and ⊥ interface between a vertical plate and the middle block (thick plate). 40

Figure 46: Microstructural observations (SEM) and chemical analysis (EDS) of the interface between two alloy 600 thin plates (// interface) after HIP process. 41

Figure 47: Microstructural observations (SEM) and chemical analysis (EDS) of particular zones of the interface between two alloy 600 thin plates (// interface) after HIP process. 42

Figure 48: Microstructural observations (SEM) and chemical analysis (EDS) of the interface between two alloy 230 thin plates (// interface) after HIP process. 42

Figure 49: Microstructural observations (SEM) and chemical analysis (EDS) of particular zones of the interface between two alloy 230 thin plates (// interface) after HIP process. 43

Figure 50: Microstructural observations (SEM) and chemical analysis (EDS) of the interface between a thin plate and a thick plate of alloy 600 (⊥ interface) after HIP process. 43

Figure 51: Microstructural observations (SEM) and chemical analysis (EDS) of the interface between a thin plate and a thick plate of alloy 230 (⊥ interface) after HIP process. 44

Figure 52: Tensile curves obtain during tests at room temperature on alloy 600 mock-ups (base material, one interface and two interfaces) after HIP process. 47
Figure 53: Gage length, fracture surface observation of tensile samples after room temperature test extracted from base material and interface alloy 600 mock-ups. 47

Figure 54: Tensile curves obtain during tests at room temperature on alloy 230 mock-ups (base material, one interface and two interfaces) after HIP process. 48

Figure 55: Gage length, fracture surface observation of tensile samples after room temperature test extracted from base material and interface alloy 230 mock-ups. 48

Figure 56: Tensile curves obtain during tests at 870°C on alloy 600 mock-ups (base material and two interfaces) after HIP process. 49

Figure 57: Tensile curves obtain during tests at 870°C on alloy 230 mock-ups (base material and two interfaces) after HIP process. 49

Figure 58: Close view of the tensile curves obtain during tests at 870°C on alloy 230 interface mock-up after HIP process. 50

Figure 59: Gage length and fracture surface observation of tensile samples after 870°C test extracted from base material and interface mock-ups for both alloys, 600 and 230. 50

Figure 60: Close observation of 870°C tensile sample fracture surfaces from alloy 600 and alloy 230 interface mock-ups (OM). 51

Figure 61: Charpy V-notch impact strength of alloy 600 base material and interface after HIP process, comparison with literature [600-1]. 52

Figure 62: Charpy V-notch impact strength of alloy 230 base material and interface after HIP process, comparison with literature [230]. 52

Figure 63: Creep curves obtain during tests at 870°C on alloy 600 mock-ups (base material and two interfaces) after HIP process. 53

Figure 64: Close view of the beginning of the creep curves obtain during tests at 870°C on alloy 600 mock-ups (base material and two interfaces) after HIP process. 53

Figure 65: Creep curves obtain during tests at 870°C on alloy 230 mock-ups (base material and two interfaces) after HIP process. 54

Figure 66: Close view of the beginning of the creep curves obtain during tests at 870°C on alloy 230 mock-ups (base material and two interfaces) after HIP process. 54

Figure 67: Gage length and fracture surface observation of creep samples after 870°C test extracted from base material and interface mock-ups for alloy 600. 55

Figure 68: Gage length and fracture surface observation of creep samples after 870°C test extracted from base material and interface mock-ups for alloy 230. 55

Figure 69: Strain-stress data obtained after 100h during the creep tests on alloys 600 and 230 base material after HIP process and comparison of test results with literature data [600-1], [230]. 56

Figure 70: Comparison of room temperature fatigue test results on alloys 600 and 230 base material with literature data [600-1], [230]. 56

Figure 71: Comparison of room temperature fatigue behavior of alloys 600 and 230 base material and interface mock-up. 57

Figure 72: Gage length and fracture surface observation of fatigue samples after room temperature test extracted from base material and interface mock-ups for alloy 600 on the left and alloy 230 on the right. 57

Figure 73: Comparison of the cycle 100 recorded during fatigue tests at room temperature with a total strain range of 0.4 % for alloys 600 and 230. 58

Figure 74: Fatigue test results at 870°C done on alloys 600 and 230 base material. 58

Figure 75: Comparison of fatigue test results done at 870°C on alloy 230 base material with literature data [230]. 59

Figure 76: Evolution of the maximum stress and the minimum stress (absolute value) recorded during room temperature fatigue tests done on alloy 600 base material and interface mock-up. 59

Figure 77: Evolution of the maximum stress and the minimum stress (absolute value) recorded during room temperature fatigue tests done on alloy 230 base material and interface mock-up. 60

Figure 78: Evolution of the maximum stress and the minimum stress (absolute value) recorded during fatigue tests done at 870°C on alloy 600 base material. 60

Figure 79: Evolution of the maximum stress and the minimum stress (absolute value) recorded during fatigue tests done at 870°C on alloy 230 base material. 61

Figure 80: Example of modified interface shape between to Ni-based alloy part in solar receivers: initial plat interface on the left, dovetail shape interface on the right. 62

Figure 81: Example of modified interface shape between to Ni-based alloy part in solar receivers: initial flat interface on the left, full penetration-welding interface on the right. 62

## List of Tables

Table 1: Bibliographic study on CSP solar receivers with best alloys selection 10

Table 2: Bibliographic study on gas turbine combustion chamber with best alloys selection 11

Table 3: Alloys selected for manufacturing the solar receiver modules benchmark 11
Table 4: Color code for alloys comparison 12

Table 5: Weighting of properties for benchmark alloys' score 17

Table 6: Score of the selected alloys 18

Table 7: Chemical composition in Al, Si and Ti of Ni-based alloy samples tested in CNRS apparatus. 23

Table 8: Mass variation of the samples after 24 h oxidation in a muffle furnace at 1200 K and 1400 K. 25

Table 9: Mass loss during oxidation for HEATEK coating on H230 alloy 26

Table 10: Mock-up references 29

Table 11: Summary of contacted material suppliers answers concerning alloys 230 and 600 demand. 30

Table 12: Benchmark alloys' score concerning physical properties 67

Table 13: Benchmark alloys' score concerning thermomechanical properties 68

Table 14: Benchmark alloys' score concerning complementary data 69

## List of References

### Alloys data sheets

[CODAP] Code de Construction des Appareils à Pression, 2010, Division 2.

[800H-1] Incoloy® alloy 800H data sheet, publication number SMC-047, Special Metals Corporation, September 2004 (http://www.specialmetals.com/assets/smc/documents/alloys/incoloy/incoloy-alloys-800h-800ht.pdf),

[800H-2] VDM® Alloy 800 H/HP, Nicrofer 3220 H/HP, Data Sheet No. 4129, Revision 03, February 2019 (https://www.vdm-metals.com/fileadmin/user upload/Downloads/Data Sheets/Data Sheet VDM Alloy 800 H revision 03.pdf),

[330] VDM® Alloy 330, Nicrofer 3718, Data Sheet No. 4102, August 1997 (https://www.vdm-metals.com/fileadmin/user upload/Downloads/Data Sheets/Data Sheet VDM Alloy 330 DS.pdf),

[600-1] Inconel® alloy 600 data sheet, publication number SMC-027, Special Metals Corporation, September 2008 (http://www.specialmetals.com/assets/smc/documents/alloys/inconel/inconel-alloy-600.pdf),

[600-2] VDM® Alloy 600/600H, Nicrofer 7216/7216H, Data Sheet No. 4007, March 2002 (https://www.vdm-metals.com/fileadmin/user upload/Downloads/Data Sheets/Data Sheet VDM Alloy 600.pdf),

[601-1] Inconel® alloy 601 data sheet, publication number SMC-028, Special Metals Corporation, February 2005 (http://www.specialmetals.com/assets/smc/documents/alloys/inconel/inconel-alloy-601.pdf),

[601-2] VDM® Alloy 601, Nicrofer 6023 H, Data Sheet No. 4103, September 2017 (https://www.vdm-metals.com/fileadmin/user upload/Downloads/Data Sheets/Data Sheet VDM Alloy 601.pdf),

[602CA-1] VDM® Alloy 602 CA, Nicrofer 6025 HT, Data Sheet No. 4137, Revision 01, January 2017 (https://www.vdm-metals.com/fileadmin/user upload/Downloads/Data Sheets/Data Sheet VDM Alloy 602 CA.pdf),

[617-1] Inconel® alloy 617 data sheet, publication number SMC-029, Special Metals Corporation, March 2005 (http://www.specialmetals.com/assets/smc/documents/alloys/inconel/inconel-alloy-617.pdf),

[617-2] VDM® Alloy 617, Nicrofer 5520 Co, Data Sheet No. 4019, January 2005 (https://www.vdm-metals.com/fileadmin/user upload/Downloads/Data Sheets/Data Sheet VDM Alloy 617.pdf),

[617-3] Haynes® 617 alloy data sheet, H-3171C, Haynes International 2017 (https://www.haynesintl.com/alloys/alloy-portfolio/High-temperature-Alloys/haynes-617-alloy),

[690-1] Inconel® alloy 690 data sheet, publication number SMC-079, Special Metals Corporation, October 2009 (http://www.specialmetals.com/assets/smc/documents/alloys/inconel/inconel-alloy-690.pdf),

[690-2] VDM® Alloy 690, Nicrofer 6030 Co, Data Sheet No. 4038, September 2015 (https://www.vdm-metals.com/fileadmin/user upload/Downloads/Data Sheets/Data Sheet VDM Alloy 690.pdf),

[HR120] Haynes® HR120 alloy data sheet, H-3125E, Haynes International (https://www.haynesintl.com/alloys/alloy-portfolio/High-temperature-Alloys/HAYNES-HR-120-ALLOY.aspx),

[HR160] Haynes® HR160 alloy data sheet, H-3129C, Haynes International 2017 (https://www.haynesintl.com/alloys/alloy-portfolio/High-temperature-Alloys/HAYNES-HR-160-ALLOY.aspx),
[230] Haynes® 230 alloy data sheet, H-3000H, Haynes International 2007 (https://www.haynesintl.com/alloys/alloy-portfolio/High-temperature-Alloys/HAYNES-230-ALLOY.aspx),

[X] Hastelloy® X alloy data sheet, H-3009C, Haynes International 1997 (https://www.haynesintl.com/alloys/alloy-portfolio/High-temperature-Alloys/HASTELLOY-X-alloy),

Publications

[1] CLIFFORD K. Ho, Advances in central receivers for concentrating solar applications, Solar Energy, 152, 38-56, 2017,

[2] OLIVARES R. I. and al., Thermogravimetric Study of Oxidation-Resistant Alloys for High-Temperature Solar Receivers, Journal of The Minerals, Metals & Materials

[3] ORTEGA J. and al., Coupled modeling of a directly heated tubular solar receiver for supercritical carbon dioxide Brayton cycle: Structural and creep-fatigue,

[4] RODRIGUEZ-SANCHEZ M.R. and al., New designs of molten-salt tubular-receiver for solar power tower, SolarPACES 2013, Energy Procedia 49, 204-513, 2014,

[5] RADKE E. F. and al., Creep-Fatigue Design Applied to Molten Salt Solar Receivers, ASME Symposium on Elevated Temperature Application of Materials for Fossil, Nuclear, and Petrochemical Industries, March 25-27, 2014,

[6] DEODESHMUKH V. P. and al., Long-term oxidation behavior of selected high temperature alloys, 11th International Symposium on superalloys, September 14-18, 2008, Champion, Pennsylvania, USA.

[7] DEODESHMUKH V. P. and al., Long-term oxidation behavior of various Chromia-forming alloys: Effect of thermal cycle length, ASME Turbo Expo 2009: Power for Land, Sea and Air GT2009, June 8-12, 2009, Orlando, Florida, USA,

[8] WEI M. and al., Fluid flow distribution optimization for minimizing the peak temperature of a tubular solar receiver, Energy, 91, 615-677, 2015,

[9] COUTSOURADIS D. and al., Nitridation attack in a simulated gas turbine combustion environment, Materials for Advanced Power Engineering, Part II, 1263-1272, 1994,

[10] ROTHMAN M. F., Oxidation Resistance of Gas Turbine Combustion Materials, Gas Turbine Conference and Exhibit, March 18-21, 1985, Houston, Texas,

[11] H. NICKEL, F. SCHUBERT, H. BREITLING, E. BODMANN, Development and qualification of materials for structural components for the high temperature gas-cooled-reactor, Nuclear Engineering and Design, 121, 183-192, 1990.
List of Acronyms and Abbreviations

<table><thead><tr><td>Acronym/abbreviation</td><td>Meaning/full text</td></tr></thead><tbody><tr><td>AALB</td><td>Aalborg CSP</td></tr><tr><td>ARRA</td><td>Arraela S.L.</td></tr><tr><td>BSE</td><td>Back Scattering Electron</td></tr><tr><td>CA</td><td>Consortium Agreement</td></tr><tr><td>CEA</td><td>Commissariat à l'Energie Atomique et aux Energies Alternatives</td></tr><tr><td>CIEMAT</td><td>Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas</td></tr><tr><td>CNRS</td><td>Centre National de la Recherche Scientifique</td></tr><tr><td>CO</td><td>Confidential</td></tr><tr><td>CSP</td><td>Concentrated Solar Power plant</td></tr><tr><td>D</td><td>Deliverable</td></tr><tr><td>EDS</td><td>Energy Dispersive Spectroscopy</td></tr><tr><td>EU</td><td>European Union</td></tr><tr><td>EURO</td><td>Euronovia</td></tr><tr><td>FISE</td><td>Fraunhofer Institute for Solar Energy Systems ISE</td></tr><tr><td>FTIR</td><td>Fourier Transform InfraRed spectroscopy</td></tr><tr><td>HIP</td><td>Hot Isostatic Pressing</td></tr><tr><td>HT</td><td>High Temperature</td></tr><tr><td>IR</td><td>Infra-Red</td></tr><tr><td>M</td><td>Month</td></tr><tr><td>MS</td><td>Milestone</td></tr><tr><td>OM</td><td>Optical Microscopy</td></tr><tr><td>ORC</td><td>Orcan Energy GmbH or Organic Rankine Cycle</td></tr><tr><td>PU</td><td>Public</td></tr><tr><td>SE</td><td>Secondary Electron</td></tr><tr><td>TIG</td><td>Tungsten Inert Gas</td></tr><tr><td>WP</td><td>Work Package</td></tr><tr><td>YS</td><td>Yield Strength</td></tr></tbody></table>
Independent of the coolant type for the CSP that is representative of the working temperature and oxidizing or corrosive environment in the solar receiver, one can notice that Nickel-based alloys are mostly preferred over iron-based ones and finally selected as the best ones. In the highest temperature applications using gas as coolant (supercritical CO₂ and air), the alloy 230 is the preferred one. These choices have been made regarding the mechanical properties of the alloys and the environmental resistance.

This study has been enriched by adding other high temperature components that work in severe conditions: combustion chambers of gas turbines. Two relevant publications have been found concerning alloys selection for the gas turbine chambers. These new results are summarized in Table 2 (best alloys highlighted in red).

<table><caption>Table 2: Bibliographic study on gas turbine combustion chamber with best alloys selection</caption><thead><tr><th>Ref.</th><th>Environment</th><th colspan="6">Alloys selected</th></tr></thead><tbody><tr><td>[9]</td><td>Combustion gas</td><td>X</td><td>230</td><td>617</td><td>263</td><td></td><td></td></tr><tr><td>[10]</td><td>Combustion gas</td><td>X</td><td>230</td><td>617</td><td></td><td>188</td><td>88</td></tr><tr><td></td><td>Nickel-based alloys</td><td>Iron-based alloys</td><td>Cobalt-based alloys</td><td>Copper-based alloys</td><td></td><td></td><td>Best alloys</td></tr></tbody></table>

As for combustion chamber applications, Nickel-based alloys are the best choice with a preference for the alloy 230.

## 2.2 ALLOYS SELECTION FOR SOLAR RECEIVER MATERIAL BENCHMARK

As this benchmark concerns the alloys used for the surface in contact with air at high temperature (outer + inner surface of the solar receiver modules and manifolds), the selected alloys need high temperature oxidation resistance but also high temperature mechanical properties (inside pressure, thermomechanical fatigue, creep...). The selected alloys are listed in Table 3 with some general information about them.

<table><caption>Table 3: Alloys selected for manufacturing the solar receiver modules benchmark</caption><thead><tr><th>Alloy type</th><th>Commercial reference</th><th>ISO reference</th><th>Major chemical elements</th><th>Major applications</th></tr></thead><tbody><tr><td rowspan="2">Iron-based alloys</td><td>800H</td><td>1.4876</td><td>Fe-Ni-Cr</td><td>Automotive, Chemical Process Industry, Energy engineering...</td></tr><tr><td>330</td><td>1.4886</td><td>Fe-Ni-Cr</td><td>Chemical Process Industry</td></tr><tr><td rowspan="10">Nickel-based alloys</td><td>602 CA (6025HT)</td><td>2.4633</td><td>Ni-Cr-Fe-Al</td><td>Automotive, Oil and Gas, Chemical Process Industry, Energy engineering...</td></tr><tr><td>690</td><td>2.4642</td><td>Ni-Cr-Fe</td><td>Oil and Gas, Chemical Process Industry, Energy engineering...</td></tr><tr><td>214</td><td>2.4646</td><td>Ni-Cr-Al</td><td>Aerospace, Chemical Process Industry, Energy engineering...</td></tr><tr><td>617</td><td>2.4663</td><td>Ni-Cr-Co-Mo</td><td>Aerospace, Automotive, Chemical Process Industry, Energy engineering...</td></tr><tr><td>X</td><td>2.4665</td><td>Ni-Cr-Fe-Mo</td><td>Aerospace, Automotive, Chemical Process Industry, Energy engineering...</td></tr><tr><td>230</td><td>2.4733</td><td>Ni-Cr-W-Mo</td><td>Aerospace, Automotive, Chemical Process Industry, Energy engineering...</td></tr><tr><td>600</td><td>2.4816</td><td>Ni-Cr-Fe</td><td>Aerospace, Automotive, Oil and Gas, Chemical Process Industry, Energy engineering...</td></tr><tr><td>601</td><td>2.4851</td><td>Ni-Cr-Fe</td><td>Automotive, Chemical Process Industry, Energy engineering...</td></tr><tr><td>HR-120</td><td>2.4854</td><td>Ni-Fe-Cr</td><td>Chemical Process Industry, Energy engineering...</td></tr><tr><td>HR-160</td><td>2.4880</td><td>Ni-Co-Cr-Si</td><td>Chemical Process Industry, Energy engineering...</td></tr></tbody></table>

Alloy 600 is the reference material for this study

Two iron-based alloys have been selected for the benchmark: alloy 800H and alloy 330. As the first one is an unavoidable alloy in energy industry, it needs to be studied. The other one, the alloy 330, is presented by manufacturers as a good alternative for alloy 800H and seems to be interesting. The other selected alloys are Nickel-
based ones principally used in chemical process industry and energy engineering thanks to their thermomechanical properties. The alloy 600 serves as a reference for this benchmark.

These alloys are produced by four major manufactures worldwide: Haynes International, Special Metals, Thyssenkrupp, VDM Metals.

For the rest of the document, the alloys are referenced by their commercial names. The following color code is used in order to improve visibility (see Table 4).

<table><caption>Table 4: Color code for alloys comparison</caption><thead><tr><th colspan="4">Color code</th></tr></thead><tbody><tr><td>800H</td><td>690</td><td>X</td><td>601</td></tr><tr><td>330</td><td>214</td><td>230</td><td>HR-120</td></tr><tr><td>602 CA</td><td>617</td><td>600</td><td>HR-160</td></tr></tbody></table>

## 2.3 ALLOYS COMPARISON

Previous tests on first generation HIP assembled solar receivers installed in the Themis tower showed that the highest temperature measured on the surface insulated reached 875°C. This temperature serves as a reference in the comparisons if possible. The data used in the following comparisons come from suppliers' data only. No internal tests have been done to complete this benchmark.

### 2.3.1 High temperature oxidation and physical properties

The first comparisons concern the high temperature interaction of the alloys with high temperature atmosphere, i.e. high temperature oxidation and nitridation. The results are shown in Figure 1.

<figure><img src="image_6.png" /><figcaption>Figure 1: Comparison of alloys high temperature oxidation and nitridation performance</figcaption></figure>

The best alloy is the alloy 214 due to its high content of aluminum but the alloy 230 is also not bad. Alloys 617 and X also show good oxidation resistance but are poor in nitridation. Concerning the only Fe-based alloy with quantitative data, alloy 800H, its oxidation resistance is very poor compared to the other alloys. The reference alloy 600 has a good nitridation resistance but not really a good behavior for high temperature oxidation.

Two physical properties of the benchmark alloys have also been examined (Figure 2): the thermal conductivity, important to conduct the heat inside the receiver, and the thermal expansion, property that can produce important stress in junctions inside the receiver but also with fixed parts like manifolds. At 875°C, the best alloy for thermal conductivity is again the alloy 214 for the thermal conductivity and quite not bad concerning thermal expansion. The
alloy 600, the reference for this study is also good. However, the alloys 230, 617 and X, which show good thermal expansion, are not that good in thermal conductivity due to their refractory element content. Once again, the Fe-based alloys are not well positioned in the ranking with quite important thermal expansion coefficient.

<figure><img src="image_7.png" /><figcaption>Figure 2: Comparison of alloys thermal conductivity and thermal expansion</figcaption></figure>

## 2.3.2 Mechanical properties

The high temperature mechanical properties comparison is also important for this benchmark. Indeed, the solar receiver modules will sustain important stress in working conditions due to the inside pressure, the high temperature level but also its variation.

The first properties concern the tensile behavior of the selected alloys. Yield strength at 0.2% offset and elongation to rupture comparison are presented in Figure 3.

<figure><img src="image_8.png" /><figcaption>Figure 3: Comparison of alloys high temperature tensile properties (Yield strength at 0.2% offset and elongation)</figcaption></figure>
The alloys 230 and 617 are the best ones in this case. Indeed, while the alloy 214 presents the best yield strength at 875°C, its elongation to rupture is quite poor.

Another important property concerning the alloy employed for manufacturing the solar receiver modules is its fatigue behavior. Comparing high temperature fatigue life close to the CSP working temperature would be very interesting and more representative. However, common alloy fatigue data concerns tests results at room temperature. Therefore, the fatigue behavior comparison of the alloys is done using room temperature data when they are available. Figure 4 shows that the alloys 230, 617 and X are well positioned, even if the alloy 690 is the best for the high amplitude tests. The only Fe-based material with available data, the alloy 800H, is the worst of all. The alloy 214 cannot be evaluated as no data has been found.

<figure><img src="image_9.png" /><figcaption>Figure 4: Comparison of alloys fatigue properties (number of cycles to rupture at room temperature)</figcaption></figure>

Finally, the last thermomechanical property evaluated in this benchmark is creep. This mechanical characteristic is dominating as the solar receiver modules are considered as pressure vessels and subject to the European pressure vessel directive (2014/68/UE). Although the European pressure vessel directive needs the time data to obtain a deformation of 1% after 100000h, this information is currently not available in the literature. Therefore, in this benchmark, the comparison of the alloys has been done for the three cases available, depending on the time to obtain 1% of creep deformation: 100h, 1000h and 10000h. The results are presented in Figure 5.

In all cases, the alloy 617 is the best material, followed by the alloy 230. The alloy 214, good for 100h and 1000h to obtain 1% creep deformation, falls in the ranking for 10000h. This should be more important for longer lifetime. One can also notice that the reference material, the alloy 600, is not well positioned. The Fe-based alloy 800H is quite well placed in the creep ranking.
<figure><img src="image_10.png" /><figcaption>Figure 5: Comparison of alloys creep properties (stress to obtain 1% creep after 100h, 1000h and 10000h)</figcaption></figure>

### 2.3.3 Other comparisons

The material benchmark cannot be exhaustive without comparing the alloys potential compatibility with HIP process and their cost.

#### 2.3.3.1 HIP compatibility

HIP compatibility of an alloy is difficult to estimate without making real tests of diffusion bonding. However, the CEA has a quite important feedback on important criteria to realize good diffusion bounded junctions. The first one concerns the concentration of principal elements that could form oxides and/or carbides in the alloys (Si, Ti and Al). This approach is qualitative but not quantitative. The comparison of the benchmark materials concerning these elements is presented in Figure 6.

<figure><img src="image_11.png" /><figcaption>Figure 6: HIP compatibility of benchmark alloys depending on their chemical composition</figcaption></figure>
The reference alloy 600 is quite good because of its low content of these problematic elements, similarly to the alloys 230 and X. Alloys 617 and 214 aluminium content should be a real issue, especially for the second one, which has the highest level of all materials. Strong difficulties can be expected for these alloys. However, one must be attentive to the fact that even if a chemical element is not specified in the alloy standard composition, this element in question might still be present. Indeed, the CEA feedback on alloy 230 shows that the alloy 230 contains aluminium especially on the surface in plate cases while it is not specified in this alloy standard composition.

Another important aspect of alloy compatibility with HIP process is its ability to be welded using conventional methods like Tungsten Inert Gas welding.

As mentioned above, the CEA has a feedback on diffusion bonding of a quite large range of alloys. Concerning the benchmark materials, only the alloys 600, 617, X and 230 have been experimented with HIP diffusion bonding. The alloys 600 and 230 are the simplest to employ, followed by the alloy X and then the alloy 617. However, a specific surface preparation is needed in all cases to obtain good junctions.

### 2.3.3.2 Cost estimation

One last important aspect concerning material choice for manufacturing solar receiver modules is its cost. For this part of the study, three material manufacturers have been contacted. As retailers can also be a providing source of special alloys, one of them has also been called to compare the costs. The questions asked were as follows:

- Do they provide each of the benchmark alloys? If they do, cost estimations in €/kg for plates with a thickness of 5mm or similar.

- Do they provide each of the benchmark alloys in tube form? If they do, cost estimations in €/kg for tubes with an outer diameter of 8 mm and a thickness of 1mm or similar.

The results obtained are plotted in a graph in Figure 7 in the case of plate provision. These results are just indicative costs. They would be adjusted in a case of a real industrial application (amount of alloy supplied, size of the plates...).

<figure><img src="image_12.png" /><figcaption>Figure 7: Comparison of plate cost</figcaption></figure>

First of all, one can see that the suppliers do not sell all the benchmark alloys. Moreover, some of them, alloys 214 and HR-160, are sold by only one manufacturer because of patented compositions and manufacturing process (Haynes International). This can explain why these two alloys are quite expensive compared to the other ones.

Secondly, the alloys 800H and 330 are the cheapest ones. That is explained by the fact that they are the only iron-based materials of the benchmark, as Nickel is a more expensive constitutive element in comparison. For the other materials, the reference alloy 600 appears to be the cheapest one. Other well positioned alloys in the physical and mechanical properties comparison (alloys 617, X and 230) are twice or three times more expensive. This is explained
by their chemical composition containing expensive refractory elements (molybdenum, cobalt, tungsten) that implies more complex manufacturing process.

### 2.3.4 Benchmark results

Using all the properties comparisons exposed in the previous paragraphs, the alloys have been classified using a weighting for each property depending on its significance for manufacturing high temperature solar receiver modules. The most important properties have a weighting of 6 while less important ones are weighted with a 1. The properties weighting is summarized in Table 5.

Concerning physical properties, the most important is the high temperature oxidation resistance while the least one is the nitridation resistance. The thermal conductivity and expansion behavior have an average rating, as a low thickness of alloy is expected for manufacturing the solar receiver modules.

For mechanical properties, the highest weightings have been put on the tensile YS and the fatigue response of the alloys. The elongation and the creep behavior (to obtain 1% of deformation after 10000h) have an average rating, as the expected pressure inside the module is relatively low. Creep properties for reduced time to obtain a deformation of 1% are not important.

If the information is available, the alloy HIP compatibility and its cost have an important weighting because of their importance for the project.

<table><caption>Table 5: Weighting of properties for benchmark alloys' score</caption><thead><tr><th>Physical characteristic</th><th>High temperature oxidation</th><th>High temperature nitridation</th><th>Thermal conductivity</th><th>Thermal expansion</th></tr></thead><tbody><tr><th>Weight</th><td>6</td><td>1</td><td>3</td><td>2</td></tr></tbody></table>

<table><thead><tr><th rowspan="2">Mechanical characteristic</th><th rowspan="2">YS at 0.2% offset</th><th rowspan="2">Elongation</th><th rowspan="2">Fatigue</th><th colspan="3">Creep (stress to obtain 1% of deformation)</th></tr><tr><th>100h</th><th>1000h</th><th>10000h</th></tr></thead><tbody><tr><th>Weight</th><td>5</td><td>4</td><td>5</td><td>1</td><td>1</td><td>3</td></tr></tbody></table>

<table><thead><tr><th>Other characteristics</th><th>HIP compatibility</th><th>Alloy cost (plate case)</th></tr></thead><tbody><tr><th>Weight</th><td>6</td><td>5</td></tr></tbody></table>

Then, the twelve alloys have been ranked from the best to the worst and the score for each property corresponds to the rank multiplied by the weighting. For example, the best alloy concerning thermal conductivity has a score of 12 (rank) x 3 (weighting) = 36 points while the worst has a score of 1 x 3 = 3 points. If for a specific characteristic, data are not available for some alloys, the best alloy has a rank of 12 minus the number of alloys without data. As an example, information concerning high temperature oxidation cannot be found for alloys 690, 602 CA and 330. So the best alloy will have a rank of 9 (12 alloys - 3 alloys) and a score of 9 x 6 = 54 points for this property. The alloys without properties are granted with a score of 0. The detailed score calculation for each property has been put in Annex 2 (Table 12 to Table 14).

The final alloys benchmark ranking can be found in Table 6. For better visualization, a graphic representation of these results has been made and normalized with the highest score (Figure 8). One has to keep in mind that this ranking methodology, two very close results are artificially distinguished but as many properties are compared and the fact that the two best alloys' score is very high compared to the others, this method has been selected. Similarly, by removing the no-data, the weighting is biased. However, the fact that some properties are not quantified by the material suppliers indicates that these characteristics are not the most important ones for these alloys.

The best material of the benchmark is the alloy 230. That is in adequacy with the preliminary bibliographic review (2.1). The second one is the alloy 617 with a slightly lower rating. It is not surprising because both alloys are currently compared for high temperature applications since many years [11].

The third alloys ex aequo of the benchmark are alloys 600 and X. So, the reference alloy is still well positioned.
At the opposite, the worst alloys for manufacturing solar receivers are alloys 602 CA and 330. It is mainly because of their low mechanical properties at the high working temperature needed for the solar receivers when these data are available.

<table><caption>Table 6: Score of the selected alloys</caption><thead><tr><th></th><th>Alloy</th><th>230</th><th>617</th><th>600</th><th>X</th><th>214</th><th>690</th><th>800H</th><th>HR-120</th><th>HR-160</th><th>601</th><th>330</th><th>602 CA</th></tr><tr><th></th><th>Score</th><td>308</td><td>304</td><td>248</td><td>248</td><td>233</td><td>176</td><td>175</td><td>169</td><td>165</td><td>143</td><td>107</td><td>94</td></tr><tr><th></th><th>W</th><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr></thead><tbody><tr><th>High Temperature Nitridation</th><td>1</td><td>5</td><td>4</td><td>6</td><td>3</td><td>7</td><td></td><td></td><td></td><td></td><td>1</td><td>2</td><td></td></tr><tr><th>High Temperature Oxidation</th><td>6</td><td>48</td><td>36</td><td>24</td><td>42</td><td>54</td><td></td><td>6</td><td>30</td><td>18</td><td>12</td><td></td><td></td></tr><tr><th>Thermal Conductivity</th><td>3</td><td>15</td><td>27</td><td>33</td><td>18</td><td>36</td><td>30</td><td>21</td><td>12</td><td>24</td><td>3</td><td>6</td><td>9</td></tr><tr><th>Thermal Expansion</th><td>2</td><td>24</td><td>22</td><td>18</td><td>20</td><td>8</td><td>12</td><td>2</td><td>6</td><td>10</td><td>14</td><td>4</td><td>16</td></tr><tr><th>Yield Strength at 0.2% Offset</th><td>5</td><td>55</td><td>50</td><td>25</td><td>45</td><td>60</td><td>35</td><td>10</td><td>40</td><td>30</td><td>15</td><td>20</td><td>5</td></tr><tr><th>Elongation</th><td>4</td><td>48</td><td>44</td><td>36</td><td>20</td><td>12</td><td>40</td><td>32</td><td>16</td><td>28</td><td>24</td><td>4</td><td>8</td></tr><tr><th>Fatigue</th><td>5</td><td>30</td><td>35</td><td>10</td><td>25</td><td></td><td>15</td><td>5</td><td></td><td>20</td><td></td><td></td><td></td></tr><tr><th>Creep 100 h</th><td>1</td><td>10</td><td>12</td><td>5</td><td>9</td><td>11</td><td>4</td><td>8</td><td>1</td><td>6</td><td>7</td><td>2</td><td>3</td></tr><tr><th>Creep 1000 h</th><td>1</td><td>10</td><td>12</td><td>5</td><td>8</td><td>11</td><td>2</td><td>9</td><td>1</td><td>6</td><td>7</td><td>3</td><td>4</td></tr><tr><th>Creep 10000 h</th><td>3</td><td>30</td><td>36</td><td>12</td><td>21</td><td>24</td><td>3</td><td>27</td><td>33</td><td>18</td><td>15</td><td>6</td><td>9</td></tr><tr><th>HIP compatibility</th><td>6</td><td>18</td><td>6</td><td>24</td><td>12</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><th>Material cost</th><td>5</td><td>15</td><td>20</td><td>50</td><td>25</td><td>10</td><td>35</td><td>55</td><td>30</td><td>5</td><td>45</td><td>60</td><td>40</td></tr></tbody></table>

<figure><img src="image_13.png" /><figcaption>Figure 8: Result of the benchmark of selected alloys</figcaption></figure>
### 2.3.4.1 Experimental means

In order to complete the investigations on potential alloys for manufacturing solar receiver modules, complementary tests have been made on the four best alloys of the previous benchmark: alloy 230, alloy 617, alloy 600 and alloy X. The alloy HR-120 has also been tested in order to compare the optical properties of an alloy at the bottom of the ranking with the best ones. The materials certificates are presented in Annex 1.

These tests have been conducted at the focus of the 1MW solar furnace of the CNRS at Odeillo (Figure 9).

<figure><img src="image_14.png" /><figcaption>Figure 9: 1MW solar furnace of the CNRS at Odeillo: (a) photography of the whole installation, (b) schematic representation of the solar furnace.</figcaption></figure>

More precisely, a specific apparatus developed by the CNRS can be installed at the focus of the solar furnace to record the optical properties of materials directly at high temperature. This facility is called MEDIASE. A picture and a schematic representation of this installation are presented in Figure 10. It consists of a stainless steel vessel with a capacity of about 60 l, equipped with a turbo-molecular pumping system. A hemispherical silica window, 35 cm in diameter, is placed in front of this vessel and allows concentrated solar radiation to heat the sample (up to 10 MW/m²). This chamber works under high vacuum (10⁻⁴ Pa), under controlled pressure, or at atmospheric pressure. The temperature of the sample is measured using a pyro-reflectometer (two wavelengths: 1.3 and 1.55 µm), developed by PROMES-CNRS, that gives the true temperature with an accuracy estimated at 1%. It is particularly important for the temperature of virgin metals (non-oxidized metals).

The emissivity of the sample is measured using a direct method. The direct method used at PROMES-CNRS is the one that corresponds directly to the definition of emissivity: the directional spectral radiance (L'λ) of the material is measured as well as its temperature to calculate the spectral radiance of the blackbody (L⁰λ) at the same temperature. The ratio of the radiances gives the spectral directional emissivity:

$$ \varepsilon'_{\lambda} = L'_{\lambda} / L_{\lambda}^{0} $$

The corresponding hemispherical emissivity $\varepsilon_{\lambda}^{\cap}$ is then calculated by integration of the directional values:

$$ \varepsilon_{\lambda}^{\cap} = \int_{0}^{\frac{\pi}{2}} \varepsilon'_{\lambda} \sin 2\theta \, d\theta $$

The measurement of the directional spectral radiance is done with a spectroradiometer (SR-5000N CI Systems) from 0° to 80° by 10° step plus 45° and 75° angles in the wavelength range of 1.4-14µm for POLYPHEM alloys. The spectral
data is obtained with an accuracy around 2% of this wavelength range. The calibration of the pyro-reflectometer and the spectro-radiometer is made on a blackbody up to 1900 K.

The integration of the directional values of emissivity allows obtaining the hemispherical data. The integration in the whole wavelength range permits to obtain the total emissivity, and the approximation for the solar absorptivity is obtained by integration in the wavelength range 1.4-2.8 µm.

The alloy samples are discs with a diameter of 40 mm with a thickness of 2.5mm. The surface is sand-blasted in order to not interfere with the measurement and to have the same surface roughness for each kind of alloys. The emissivity tests are done under high vacuum and at temperature up to 1300 K.

<figure><img src="image_15.png" /><figcaption>Figure 10: MEDIASE facility: (a) photography of the apparatus, (b) schematic representation.</figcaption></figure>

Some other measurements are conducted on oxidised samples at 1200 K and 1400 K at atmospheric pressure.

Other emissivity measurements are performed at room temperature. In this case, the samples are smaller than the MEDIASE ones: 25 mm in diameter, thickness of 2.2 mm.

### 2.3.4.2 Results of high temperature tests (MEDIASE facility)

#### a) High vacuum tests

The emissivity in high vacuum was measured for all the alloys to have a reference data for non-oxidized materials.

When the alloys are compared, the results show that except for the alloy 617 at 1300 K, the alloys show the same trend concerning the total hemispherical emissivity versus temperature (Figure 11). The emissivity goes from 0.35 around 1100 K down to 0.28 at 1300 K. Only the alloy 617 still keeps the same behavior with a total emissivity above 0.3.

<figure><img src="image_16.png" /><figcaption>Figure 11: Total hemispherical emissivity at high temperature under high vacuum.</figcaption></figure>
In fact, the emissivity decreases when the temperature increases due to the smoothing of the surface at high temperature (linked to the grain coarsening). This phenomenon can be observed when studying the surface morphology (by SEM) and roughness (measured by profilometry) as shown in Figure 12 (decrease of the surface roughness parameter Sq). Once again, alloy 617 samples do not show the same trend as the roughness increases when they are exposed to HT (Sq = 1.33±0.03 µm for as received samples and Sq = 1.47±0.07 µm for HT vacuum samples).

<figure><img src="image_17.png" /><figcaption>**Figure 12: Surface evolution between as received samples and after HT vacuum tests for alloy X and alloy 230 samples with Sq roughness parameter evaluation (Root mean square height, areal extension).**</figcaption></figure>

b) Atmospheric pressure tests (air)

Concerning the measurement of the directional spectral emissivity during in situ oxidation, the results show that between angles of 0° and 60°, no difference can be observed whatever the wavelength in the range studied (1.4-14 µm). For higher angles, the spectral emissivity decreases when the angle increases (Figure 13). Another result is that the oxidation increases emissivity for long wavelengths in the infrared (same samples tested at different temperature levels, Figure 13).

<figure><img src="image_18.png" /><figcaption>**Figure 13: Directional emissivity during in situ oxidation tests in MEDIASE facility – Example of alloy HR-120.**</figcaption></figure>
When the total hemispherical emissivity $ε$ in the wavelength range 1.4 – 14 µm and the “solar absorptivity” $α$ in the wavelength range 1.4 – 2.8 µm for alloys 600, X, 230 and HR-120 are compared at different temperatures (Figure 14), some differences can be observed (higher emissivity and absorptivity for alloy X than the others for example). However, the comparison of ratio $α/ε$ (tables on Figure 14) shows no real differences, sign of similar behavior for these alloys.

In the same way, the SEM images of the surface of the alloys 600, X, 230 and HR-120 after oxidation up to 1200 K do not show significant differences, but some differences can be observed up to 1400 K (Figure 15). In all cases, the oxidized surface is full of small and numerous thin tips for tests up to 1200 K. This surface morphology evolves to globular shape oxides. Only the size varies from one alloy to another.

<figure><img src="image_19.png" /><figcaption>Figure 14: Total hemispherical emissivity $ε$ in the wavelength range of 1.4 – 14 µm (full dots) and “solar absorptivity” $α$ in the wavelength range of 1.4 – 2.8 µm (open dots) versus temperature and table of ratios $α/ε$ for alloys 600, X, 230 and HR-120.</figcaption></figure>

<figure><img src="image_20.png" /><figcaption>Figure 15: Evolution of oxidized surface after HT exposure (SEM images).</figcaption></figure>
The behavior of the alloy 617 is slightly different compared to the one of other materials. Indeed, Figure 16 shows that the solar absorptivity calculated is above the level obtained for other alloys (close to 0.9 when others are near 0.8). However, the total hemispherical emissivity is very high too. That is why the α/ε is reduced for alloy 617 at 1100 K and 1200 K compared to the others tested materials but similar at 1400 K (table on Figure 16).

<figure><img src="image_21.png" /><figcaption>Figure 16: Total hemispherical emissivity ε in the wavelength range of 1.4 – 14 µm (full dots) and “solar absorptivity” α in the wavelength range of 1.4 – 2.8 µm (open dots) versus temperature, table of ratios α/ε and surface evolution after HT exposure (SEM images) for alloy 617.</figcaption></figure>

Observing the oxidised surface of alloy 617 samples, the thin flat grains formed during oxidation in air up to 1200 K for all previous alloys are also visible on the 617 samples (left picture, Figure 16). Nevertheless, while these tips disappeared for tests up to 1400 K on previous materials, they are still present on the surface of the 617 samples (right picture, Figure 16).

The different behavior of alloy 617 compared to all the other tested can be explained by the fact that 617 samples were machined in a bar while all the others come from plates. The thermomechanical treatments are different for bars and for plates during the manufacturing process that lead to different initial microstructure and internal stress. The chemical composition differences can also influence the behavior difference of alloy 617 compared to the others. The higher content of Al and Ti in alloy 617, elements that form very stable oxides at high temperature, can explain the surface structure difference after the tests up to 1400 K (Table 7).

<table><caption>Table 7: Chemical composition in Al, Si and Ti of Ni-based alloy samples tested in CNRS apparatus.</caption><thead><tr><th rowspan="2">Alloy</th><th colspan="3">Chemical composition (wt%)</th></tr><tr><th>Al</th><th>Si</th><th>Ti</th></tr></thead><tbody><tr><td>230</td><td>0.38</td><td>0.36</td><td>&lt;0.01</td></tr><tr><td>617</td><td>0.92</td><td>0.08</td><td>0.41</td></tr><tr><td>600</td><td>0.16</td><td>0.31</td><td>0.19</td></tr><tr><td>X</td><td>0.13</td><td>0.46</td><td>&lt;0.01</td></tr><tr><td>HR-120</td><td>0.09</td><td>0.53</td><td>&lt;0.01</td></tr></tbody></table>

#### 2.3.4.3 Results of room temperature emissivity

The measurement of the emissivity at room temperature was carried out using two apparatus:

- The Perkin Elmer Lambda 950 is a laboratory two-beam scan spectrophotometer that allows monochromatic light irradiance with a minimal scan of 0.05 nm in UV/Vis and 0.2 nm in NIR. It is equipped with an integrating sphere of 150 mm diameter and the spectrum of hemispherical reflectance is obtained in a wavelength range between 250 and 2500 nm. The measurements are referenced with a standard calibrated (spectralon 99%).

- The SOC-100 HDR reflectometer (Surface Optics Corporation) is coupled with a Nicolet FTIR 6700 spectrophotometer for the wavelength range 1.25 – 25 µm. It provides hemispherical directional reflectance measurements at different detection angles from 8 to 80°. The SOC-100 is equipped with a 2π imaging hemi-ellipsoid (gold coated) to illuminate the sample from all directions using a 700°C blackbody source. A moveable mirror collects the reflected collimated light and directs it to the FTIR to obtain the reflectance spectrum. A gold plated calibrated specular or diffuse reflectance standard is used as reference during the measurement.
The emissivity is deduced from the reflectivity measurements on virgin samples and the ones oxidized in a muffle furnace during 24 h at 1200 K and at 1400 K.

Figure 17 and Figure 18 present the emissivity results obtained for all the alloys, based on the reflectivity measurements taking into account that the samples are considered opaque, for the virgin samples and for the oxidized at 1200 K and 1400 K respectively.

<figure><img src="image_22.png" /><figcaption>Figure 17: Spectral hemispherical emissivity in the wavelength range 0.25 – 25 µm for the virgin samples at room temperature</figcaption></figure>

<figure><img src="image_23.png" /><figcaption>Figure 18: Spectral hemispherical emissivity in the wavelength range 0.25 – 25 µm at room temperature for the samples oxidized at: (a) 1200 K during 24 h in air, (b) 1400 K during 24 h in air.</figcaption></figure>
At room temperature, the maximum for the blackbody radiance is around 9-10 µm. In that case, some differences can be observed for the virgin samples (Figure 17), but these are more important for the oxidized ones, with values comprised between 0.53 (HR120) and 0.82 (230) at 10 µm, as it can be seen in Figure 18. In fact, only alloy HR-120 has a very low emissivity compared to the other alloys, these latter having quite the same response close to wavelength of 10 µm. The effect of the oxidation at higher temperature tends to decrease the differences between the alloys with emissivity data comprised around 0.80 and 0.88 for all the alloys at 10 µm. One must keep in mind that the room temperature optical properties are given indicatively as the HT optical properties are the ones important regarding to the application.

Table 8 presents the mass variation of the samples after the oxidation carried out in the muffle furnace before measuring the emissivity at room temperature. A low mass gain was measured for all the samples at 1200 K but at 1400 K, the mass gain increases significantly except for HR120 and 230 that have lost mass. Observing samples after oxidizing test at 1400 K (Figure 19), the mass loss is due to oxide spalling. In fact, one can see that the alloy 600 sample and to a lesser extent the alloy X are also spalling. In fact, the mass gain for these alloys is higher than measured due to spalling. Only alloy 617 shows intact oxide layer. This could be due to its oxide composition (Al and Ti alloy 617 content).

<table><caption>Table 8: Mass variation of the samples after 24 h oxidation in a muffle furnace at 1200 K and 1400 K.</caption><thead><tr><th>T(K)</th><th>Alloy</th><th>Weight before test (g)</th><th>Weight after test (g)</th><th>Δm/m (%)</th><th>Δm/S (g/m2)</th></tr></thead><tbody><tr><td rowspan="5">1200</td><td>X</td><td>9.1953</td><td>9.1979</td><td>0.03</td><td>5.30</td></tr><tr><td>HR-120</td><td>8.7289</td><td>8.7310</td><td>0.02</td><td>4.28</td></tr><tr><td>230</td><td>9.6050</td><td>9.6077</td><td>0.03</td><td>5.50</td></tr><tr><td>600</td><td>9.2986</td><td>9.3026</td><td>0.04</td><td>8.15</td></tr><tr><td>617</td><td>9.0544</td><td>9.0589</td><td>0.05</td><td>9.17</td></tr><tr><td rowspan="5">1400</td><td>X</td><td>9.2146</td><td>9.2265</td><td>0.13</td><td>24.24</td></tr><tr><td>HR-120</td><td>8.7559</td><td>8.7250</td><td>-0.35</td><td>-62.95</td></tr><tr><td>230</td><td>9.5877</td><td>9.5826</td><td>-0.05</td><td>-10.39</td></tr><tr><td>600</td><td>9.4283</td><td>9.4377</td><td>0.10</td><td>19.15</td></tr><tr><td>617</td><td>9.0397</td><td>9.0594</td><td>0.22</td><td>40.13</td></tr></tbody></table>

<figure><img src="image_24.png" /><figcaption>Figure 19: Samples after oxidation test during 24h at 1400K and sample prints on the furnace holder.</figcaption></figure>

### 2.3.5 Characterization of the coatings developed by Arraela

Some samples of the alloy 230 were covered by a black coating made by Arraela. This coating process, called HEATEK® ROX, is compatible with the solar receiver after manufacturing (temperature lower than copper fusion temperature) and has been studied in order to examine the potential advantages of this coating on optical properties compared to naturally oxidized material.

Before measuring the radiative properties at high temperature, the behavior of these samples was studied in air at atmospheric pressure. The oxidation in air was done on two samples at respectively 1200 K and 1400 K during around 20 min. Figure 20 presents the temperature profile of sample HEATEK_2 during oxidation in air at 1200 K.
<figure><img src="image_25.png" /><figcaption>Figure 20: Evolution of the temperature and solar flux versus time during the oxidation test in air at 1200 K of the HEATEK® ROX sample.</figcaption></figure>

The mass variation was deduced from the mass measurement before and after oxidation (Table 9). It appears that 1400 K is too high for this coating as the mass loss obtained after only 20 min oxidation is quite high. Nevertheless, the coating can withstand oxidation at 1200 K. It can be noticed that the main part of the mass loss is coming from the coating if compared to the values presented in Table 8.

During the oxidation, video recording was performed and Figure 21 shows two images taken from the video and it is clearly visible that there are some vapours emitted during the oxidation at 1400 K that are not present at 1200 K. This is confirmed by the dirtiness of the optical window taken after oxidation at 1400 K (third picture in Figure 21).

<table><caption>Table 9: Mass loss during oxidation for HEATEK coating on H230 alloy</caption><thead><tr><td>Sample reference</td><td>T (K)</td><td>Weight before test (g)</td><td>Weight after test (g)</td><td>Δm/m (%)</td><td>Δm/S (g/m2)</td></tr></thead><tbody><tr><td>Heatek_2</td><td>1200</td><td>9.9043</td><td>9.9041</td><td>-0.002</td><td>-0.41</td></tr><tr><td>Heatek_3</td><td>1400</td><td>9.9386</td><td>9.8747</td><td>-0.643</td><td>-130.17</td></tr></tbody></table>

<figure><img src="image_26.png" /><figcaption>Figure 21: Pictures taken during oxidation in air for samples HEATEK_2 at 1200 K (a) and HEATEK_3 at 1400 K (b) and picture of the optical fluorine window (c).</figcaption></figure>

Room temperature emissivity measurements have been done and have to be studied. Optical properties at high temperature will be measured on the HEATEK® ROX coating up to 1200-1300 K maximum using the MEDIASE facility (to avoid degassing) by the end of the year 2020.

### 2.3.5.1 Conclusions of optical tests

The optical tests done on alloys 600, X, 230 and HR-120 samples show low differences in emissivity and absorption behavior at high temperature. Only alloy 617 properties are different (worse performance). That could be explained by the oxide composition but also by the alloy sample supply (from a bare and not from a plate compared to the
others). Room temperature emissivity characterization for a wavelength of 10 µm shows different behavior of the alloys on native samples (non-oxidized) but this is not the case for oxidized ones.

The tests on coated samples made by Arraela have started and the results will be given until the end of 2020.

### 2.3.6 Benchmark conclusions

Comparing physical and mechanical properties of high temperature alloys combined with complementary evaluations (HIP compatibility, cost), the oxidizing protective alloy benchmark results show that the Nickel-based alloy 230 is the best choice. This is confirmed by the literature study concerning solar receiver alloy selection. The reference alloy 600 is also well ranked (third place). As optical property examination does not show very different alloy behavior (on preselected alloys), the benchmark rank is still valid. For the rest of task 1.1, alloy 230 has been selected to be compared with the reference alloy 600.

Potential complementary coating made by Arraela is under examination in order to evaluate the gain of making it compared to oxidized alloy.

## 3. CHARACTERIZATION HIP MOCK-UPS MANUFACTURING

The second part of this report deals with the characterization HIP mock-ups manufacturing that serve to evaluate the mechanical properties of HIP junctions and to compare them with base material treated in the same conditions. This has been done with alloy 600 plates on one hand and with alloy 230 – the best alternative according to the previous benchmark – on the other hand.

### 3.1 MOCK-UP DESIGNS

The mock-up design have been made in order to be representative to the diffusion bonded junctions between Ni-based alloy parts that can be encounter in the real solar receiver modules (flat interfaces). Figure 22 shows these different interfaces type.

<figure><img src="image_27.png" /><figcaption>Figure 22: Schematic representations of solicited diffusion bonding junctions between Ni-based alloy parts in solar receiver.</figcaption></figure>

The first one corresponds to the interfaces between the outside plates that protect the modules from high temperature air oxidation and give them their mechanical properties. The second one is related to the interfaces between the solar receiver module and its manifolds. The third one can be found inside solar receiver module manifolds in the case they are produced using HIP process. In each case, the junction is made between two plates perpendicular one to the other.

In order to be in a representative configuration of these three different interfaces, the interface mock-ups are manufactured using:

- a middle horizontal block sample from a thick plate and machined (thickness of 8 mm)
- six vertical plates (thickness of 4.6 mm), three put above the middle part and the three others below the middle part, as presented on the left picture of Figure 23.

This configuration allows characterising the interfaces between the middle vertical plates and the intermediate block but also the middle block itself in the thickness direction of the original plate. The other vertical plates are employed to have sufficient thickness to machine the mechanical samples holding heads as the sample-solicited zones are machined only the middle plate of the vertical ones. To compare the mechanical properties of diffusion bonded junctions with base material, a second type of mock-ups using only three vertical plates is manufactured (thickness of 4.6 mm, right picture on Figure 23).

<figure><img src="image_28.png" /><figcaption>Figure 23: Mechanical characterization mock-up concepts</figcaption></figure>

Two sizes of mock-ups are manufactured depending on the size of mechanical samples extracted from them (for interfaces mock-ups and for base material mock-ups):

- Height: 68 mm, width: 80 mm, thickness 4.6 x 3 = 13.8 mm,

- Height: 108 mm, width: 80 mm, thickness 4.6 x 3 = 13.8 mm.

Several samples of one mechanical testing type are machined in mock-up in order to have the diffusion bonded interfaces inside the calibrated section. As described on Figure 24, four types of mechanical samples are manufactured:

- Type 1: Tensile samples (smallest mock-ups version, 2 mock-ups),

- Type 2: Charpy V samples (smallest mock-ups version, 1 mock-up),

- Type 3: Creep samples (biggest mock-ups version, 2 mock-ups),

- Type 4: Fatigue samples (biggest mock-ups version, 3 mock-ups).

In order to compare the mechanical properties of HIP junctions with base material, the same types and amount of samples are machined in mock-ups without interfaces. Therefore, 14 mock-ups are produced for each tested material for a total of 30 mock-ups. The mock-up references are listed in Table 10. Due to a machining mistake when extracting tensile samples from mock-ups 230-A and 600-A (samples not pull out from the middle of the mock-ups), two other mock-ups have been made, 230-O and 600-O. As shown in Figure 25, the samples extracted from mock-ups 230-O and 600-O allow characterizing both horizontal interfaces and the middle block whereas the ones from mock-ups 230-A and 600-A allow testing only one interface located on one gage length extremity, the middle block being located in the head of the samples.
<figure><img src="image_29.png" /><figcaption>Figure 24: Description of HIP junction mock-up types corresponding to mechanical testing sample types.</figcaption></figure>

<table><caption>Table 10: Mock-up references</caption><thead><tr><th rowspan="2"></th><th rowspan="2">Alloy</th><th colspan="4">Mock-up reference</th></tr><tr><th>Type 1 (tensile)</th><th>Type 2 (Charpy)</th><th>Type 3 (creep)</th><th>Type 4 (fatigue)</th></tr></thead><tbody><tr><td rowspan="2">230</td><td>Interface</td><td>230-A and 230-O</td><td>230-B</td><td>230-C and 230-D</td><td>230-E, 230-F and 230-G</td></tr><tr><td>Base material</td><td>230-H</td><td>230-I</td><td>230-J and 230-K</td><td>230-L, 230-M and 230-N</td></tr><tr><td rowspan="2">600</td><td>Interface</td><td>600-A and 600-O</td><td>600-B</td><td>600-C and 600-D</td><td>600-E, 600-F and 600-G</td></tr><tr><td>Base material</td><td>600-H</td><td>600-I</td><td>600-J and 600-K</td><td>600-L, 600-M and 600-N</td></tr></tbody></table>

<figure><img src="image_30.png" /><figcaption>Figure 25: Tensile samples extraction from mock-ups 600-A, 600-O, 230-A and 230-O.</figcaption></figure>
## 3.2 MATERIAL SUPPLY

A specific alloy 230 supply has been done to manufacture the dedicated characterization blocs. Initially, the demand concerned the purchase of a 5 mm thick plate and a 10 mm thick one. As the plate thickness provided depends on available elements in stock when the purchase is done, the purchased plates are as follow (selected supplier Haynes International):

- A plate with a thickness of 6 mm for vertical mock-up elements,

- A plate with a thickness of 9.53 mm for the middle horizontal parts.

A same purchase has been done for the reference alloy 600 but only for a 5mm plate as the CEA has in stock a 10 mm thick plate. All the material certificates have been put in Annex 3.

For information, the supplier answers contacted for plates purchase are summarized in Table 11. One can notice that the cost of specific materials like alloy 230 highly vary from one supplier to the other. On the contrary, more common ones like alloy 600 have standard cost (except for Haynes International that do not manufacture this alloy). One must keep in mind that these costs correspond to a small amount of Ni-based materials. For large scale industrial material supply, the cost will be reduced.

<table><caption>Table 11: Summary of contacted material suppliers answers concerning alloys 230 and 600 demand.</caption><thead><tr><th rowspan="3">Contacted suppliers</th><th colspan="6">Material supply</th></tr><tr><th colspan="2">Alloy 230 plate 5mm thick</th><th colspan="2">Alloy 230 plate 10mm thick</th><th colspan="2">Alloy 600 plate 5mm thick</th></tr><tr><th>Real thickness (mm)</th><th>Price per kilo (€/kg)</th><th>Real thickness (mm)</th><th>Price per kilo (€/kg)</th><th>Real thickness (mm)</th><th>Price per kilo (€/kg)</th></tr></thead><tbody><tr><td>Special Metals</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Bibus Metal</td><td></td><td></td><td></td><td></td><td>5</td><td>26.9</td></tr><tr><td>Jacquet</td><td></td><td></td><td></td><td></td><td>5</td><td>26.53</td></tr><tr><td>VDM Metals</td><td>4.9</td><td>112.5</td><td>9.52</td><td>101.5</td><td>5</td><td>22</td></tr><tr><td>Haynes international</td><td>6</td><td>56.00</td><td>9.53</td><td>42.53</td><td>5</td><td>51.79</td></tr><tr><td>NeoNickel</td><td>4.76</td><td>107.83</td><td>9.52</td><td>123.58</td><td>5</td><td>30.60</td></tr></tbody></table>

<figure><img src="image_31.png" /></figure>

Decline the demand

Purchased plates

## 3.3 MOCK-UP MANUFACTURING

### 3.3.1 Mock-up parts

Preform of the mock-up parts were firstly extracted from the supplied plates using laser-cutting technic. All parts faces were then milled in order to obtain the good dimensions. This step allows removing laser cutting affected surfaces but also initial plate surfaces to obtain fresh material. Parts were cleaned after machining steps (Figure 26).

A surface preparation was done before assembling the mock-ups.
<figure><img src="image_32.png" /><figcaption>Figure 26: Example of HIP mock-up machined parts after cleaning procedure.</figcaption></figure>

### 3.3.2 Canister manufacturing

Canisters were made of laser cut stainless steel plates parts shaped using press-brake bending procedure. Preliminary TIG welds are made on the corners of the canisters and to include the exhaust tube on the cover (Figure 27). Each canister was then identified (hammer marking).

<figure><img src="image_33.png" /><figcaption>Figure 27: HIP mock-up canisters.</figcaption></figure>

### 3.3.3 Mock-up assembly

Before the mock-up assembly, all the canisters, tools and Ni-based parts are cleaned using industrial procedure (Figure 28).

The mock-ups are then assembled on clean towels. In the case of interface mock-ups (Figure 29), the centre part is firstly put inside the canister with the tool plates ((a), Figure 29). Then, three vertical plates are put on one side of the centre one ((b), Figure 29). The other three parts are positioned on the other side ((c), Figure 29). The cover of the canister is finally placed on the assembled mock-up.

After making a complete TIG welding of the cover on the canister, each mock-up sustains a tightening test in order to validate its ability to endure properly the HIP process. To do so, the tested mock-up exhaust tube is connected to a helium tester. When the vacuum value of is low enough (leak < $2 \cdot 10^{-9}$ mbar.L/s; vacuum < $10^{-2}$ mbar), helium gas is spread slowly along welding beads beginning by the upper ones. The leakage value variation is examined during this step. If the leak value increases above $5 \cdot 10^{-8}$mbar.L/s, the test is stopped and the zone is welded again. If the leak still remains under $10^{-8}$ mbar.L/s during all the test, the mock-up goes to the next step.

A degassing step using a high vacuum system is then proceeded at room temperature during a minimum of 12 hours in order to obtain a measured vacuum less than $10^{-4}$ mbar.
<figure><img src="image_34.png" /><figcaption>Figure 28: Example of mock-up part cleaning.</figcaption></figure>

<figure><img src="image_35.png" /><figcaption>Figure 29: Example of mock-up assembly (types 3 and 4): (a) all mock up parts, tools and canister, (b) first step of the manufacturing (bottom tools + centre part), (c) set up of three vertical plates, (d) set up of the three other parts, (e) cover placed on the finalized mock-up.</figcaption></figure>
<figure><img src="image_36.png" /><figcaption>Figure 30: Tightening test example and degassing mock-up step.</figcaption></figure>

The exhaust tube of each mock-up is individually set after half a day degassing time (TIG welding). The 26 mechanical test mock-ups are then shipped to the supplier to undergo the HIP process. This has been done on week 38, 2019.

<figure><img src="image_37.png" /><figcaption>Figure 31: Interface and base material mock-ups after the HIP step (alloy 600 and alloy 230, mock-ups 600-O and 230-O not presented).</figcaption></figure>

The mock-ups are finally machined in order to extract the tests samples. Each specimen is referenced with the mock-up name and its localisation.
# 4. MICROSTRUCTURAL CHARACTERIZATION

## 4.1 SAMPLE PREPARATION AND EXPERIMENTAL PROCEDURE

The samples were coated and polished using SiC foils up to grade 2400 and diamond past up to 1 µm particles. To finish the polishing step, the samples are put in a vibratory table with 0.02 µm alumina particles.

To make optical and some electronic observations, the etching procedure used in order to reveal the microstructure of the Ni-based alloys is as follows:

* Etching solution: 100 mL of HCl + 5g of oxalic acid,

* Tension: 2V,

* Duration: 2 to 3 seconds.

The *optical microscopy* observations (OM) are made on an ALICONA Infinite Focus and a LEITZ Aristomet microscopes. The *Electron Microscopy* observation (SEM) is done on a JEOL 840a microscope. It is equipped with a *Secondary Electron (SE)* and a *Back Scattered Electron (BSE)* detectors for image acquisition and with an *Energy Dispersive Spectroscopy (EDS)* probe for chemical analysis.

## 4.2 ALLOY SURFACE TREATMENT EXPLANATION

In order to make junctions between Ni-based material parts with good mechanical properties, bonding is generally made at very high temperature, commonly over 1150°C. The high temperature helps to enhance mechanical deformation of the interfaces, to activate atomic diffusion of some elements like refractory ones (Mo, Co, W...) and grain boundary migration. However, as copper is used in inner parts to manufacture the solar receiver, the HIP process must be made below its fusion temperature, i.e. 1085°C. Consequently, difficulties can occur to make direct junctions between the Ni-based parts with good microstructural and more important, good mechanical properties.

Simple mock-ups have been made to present the microstructure of the direct interface between two machined plates using previous solar receiver HIP manufacturing process. A simple description of these mock-ups, one made up with alloy 600 plates and the other with alloy 230 plates, is shown on Figure 32.

<figure><img src="image_38.png" /><figcaption>Figure 32: Direct junction mock-ups between Ni-based plates (alloy 600 of alloy 230).</figcaption></figure>

SEM observations of the interface indicate that no migration is visible for both alloys (Figure 33). Precisely, high magnification pictures show that precipitates block the interfaces. EDS analysis of the junction line compared to the core material indicate the presence of oxides (Mg, Al and Si rich ones for alloy 600 and Al rich ones for alloy 230). These precipitates are due to the presence of slight amount of oxygen in the canister even though vacuum is made before the tightening closure. During the HIP process, the chemical elements of the alloys with high affinity with the oxygen diffuse at the surface of the plates to form oxides, which blocks the interface migration. Moreover, W rich carbides can be seen at the interface for alloy 230.

To reduce the migration of chemical elements responsible for oxide formation at the interface, a coating can be made on the plates. Normally, the consequence of this procedure is a cleaner interface, which enhances the diffusion bonded junction, particularly when the HIP process temperature is reduced compared to the reference one. This coating must be made with the correct parameters (chemical composition, thickness) in order not to interfere negatively on the interface properties.
<figure><img src="image_39.png" /><figcaption>Figure 33: Direct junction between Ni-based plates SEM observations and chemical analysis (EDS)</figcaption></figure>

## 4.3 AS RECEIVED MATERIALS

### 4.3.1 Base material microstructure

In order to understand how materials evolve during the HIP treatment, microstructural analyses have been done on the as-received material and after HIP process. A schematic representation of a plate is presented on Figure 34.

<figure><img src="image_40.png" /><figcaption>Figure 34: Schematic representation of the plates showing the important direction for the microstructural observations</figcaption></figure>

Concerning alloy 600, both type of plate (thin and thick ones) present the same microstructure as shown on Figure 35:

- Plans presenting numerous carbides (carbide precipitation zones along rolling direction). During the thermomechanical processes, as the carbides prevent grain growth, these zones show small grain size.

- Plans with few carbides (carbide free zones along rolling direction). The grains in these zones were able to grow more easily during plate manufacturing process.

<figure><img src="image_41.png" /><figcaption>Figure 35: Microstructure of alloy 600 as received plates (OM).</figcaption></figure>
However, the carbide plans are less numerous and thinner for the thin plate (with smaller carbides) compared to the thick one.

Concerning the grain size, the thick plate shows an average of 40 µm compared to the thin one, which presents a bigger one with an average of 57 µm. Regarding the histograms of the grain size fractions (in number of grains or in surface) within the as-received plates (Figure 36), the amount of big grains is slightly more important for the thin plate and the small ones are more numerous for the thick one. The accuracy of these measurements is relatively low as grain boundaries are difficult to reveal with the chemical etching and due to the presence of numerous carbides.

<figure><img src="image_42.png" /><figcaption>**Figure 36: Histograms presenting the fraction in number of grains and the surface fraction of the grains in the case of the as-received alloy 600 plates.**</figcaption></figure>

The alloys 230 as-received plates show a more homogeneous microstructure than the previous alloy. Indeed, Figure 37 shows the presence of globular carbides homogeneously distributed within the grains and at grain boundaries for both types of plates.

<figure><img src="image_43.png" /><figcaption>**Figure 37: Microstructure of alloy 230 as-received plates (OM).**</figcaption></figure>
Contrary to the alloy 600, the alloy 230 thick plate presents a bigger grain size than the thin one with an average of 51 µm and 42 µm respectively.

As shown on the histograms of Figure 38, the alloy 230 thick plate shows less numerous small grains and more big grains than the thin one.

<figure><img src="image_44.png" /><figcaption>**Figure 38:** Histograms presenting the fraction in number of grains and the surface fraction of the grains in the case of the as-received alloy 230 plates.</figcaption></figure>

### 4.3.2 Coating thickness measurement

Before the HIP process, a coating treatment has been made on all the Nickel alloy parts. An intermediate part (thick plate) and a vertical part (thin plate) of the interface mock-ups have been cut, according to the schematic representations shown on Figure 39, to measure the coating thickness on the different surfaces.

<figure><img src="image_45.png" /><figcaption>**Figure 39:** Schematic representation of the extraction of the samples for coating thickness measurement.</figcaption></figure>

Figure 40 summarizes the measurements done on alloys 600 and 230 parts on the interesting surfaces.
<figure><img src="image_46.png" /><figcaption>Figure 40: Coating thickness measurement of the thick plates (intermediate mock-up block) and the thin plates (vertical mock-up plates) for alloys 600 and 230 (SEM).</figcaption></figure>

The requested coating thickness was 2 µm in order not to interact with the assemblies mechanical properties. However, it appears that the real thicknesses obtained depend on the part side (large or thin surfaces) from x 2.2 to x 8.75 compared to the expected one due to the process employed to do this coating. Then, it seems that the coating thickness on the alloy 600 is thinner than the other alloy. It could be explained by the different chemical composition of both alloys that can affect the coating process. Although the coating thickness was more important than the requested one, the treated parts were used to manufacture the HIP mock-ups to avoid delay of task 1.1.

## 4.4 HIP TREATED MATERIALS

### 4.4.1 Base materials microstructure

It is important to observe the microstructural evolution of the HIP treated base materials to evaluate the thermal effect of the assembling process. The microstructure of the alloy 600 parts is presented on Figure 41.

<figure><img src="image_47.png" /><figcaption>Figure 41: Microstructure (OM) of alloy 600 parts after HIP process.</figcaption></figure>

A very heterogeneous microstructure can be observed in the alloy 600 thick plates with plans containing huge grains between small grain zones (left picture, Figure 41). Except for some isolated grains, this is not the case for the thin plates. This phenomenon can be related to the initial microstructure of the plates. Due to the high temperature during the HIP step, on the one hand, some grains contained in the carbide free zones can grow freely until they reach precipitated zones. On the other hand, these precipitates block the grains contained in the carbide zones. In the case of the thin plates, it seems that the carbides are not able to block the grain boundary migration. Therefore, a more homogeneous microstructure can be observed (right picture, Figure 41). Some big grains can also be seen.
Due to the presence of very big grains (especially for the thick plate), the grain size of the alloy 600 parts is very difficult to evaluate. Some measures have been done setting aside the biggest grains for both plate types and the grain size has an average of 41 µm for the thick plates and 40 µm for the thin ones. As shown in Figure 42, the grain distribution in both plate types in these zones is the same. It is representative of an increase of the smallest grains in the as received materials.

<figure><img src="image_48.png" /><figcaption>**Figure 42:** Histograms presenting the fraction in number of grains and the surface fraction of the grains in the case of the alloy 600 plates after HIP process in the small grain zones.</figcaption></figure>

Concerning alloy 230, both plate types show homogeneous microstructure and the same evolutions compared to the as received material. As presented on Figure 43, tungsten rich carbides are more fragmented due to the HIP process and secondary chromium rich carbides have precipitated on grain boundaries and in grains. These second type of carbides are formed during the cooling phase of the HIP process, as they are not stable at the highest HIP process temperature.

<figure><img src="image_49.png" /><figcaption>**Figure 43:** Microstructure (OM) of alloy 230 parts after HIP process.</figcaption></figure>
Concerning the grain size, an important increase is observed compared to the as received material with an average grain size of 131 µm for the thick plates and 92 µm for the thin ones. This evolution can be seen on the histograms presenting the fraction in number of grains and the surface fraction of the grains (Figure 44), the small grains have disappeared while the big ones have increased. However, the tungsten rich carbides are sufficient to limit the grain growth during the HIP process below 210 µm in diameter.

<figure><img src="image_50.png" /></figure>

**Figure 44:** Histograms presenting the fraction in number of grains and the surface fraction of the grains in the case of the alloy 230 plates after HIP process.

### 4.4.2 Interfaces microstructure

As shown on Figure 45, the interface mock-ups contain two types of junctions between Nickel alloy parts:

- Interfaces between two thin plates called // interface in the rest of the document,

- Interfaces between a thin plate and the intermediate block (thick plate) called ⊥ interface in the rest of the document.

<figure><img src="image_51.png" /></figure>

**Figure 45:** Schematic representations of the observed interfaces: // interface between two vertical thin plates and ⊥ interface between a vertical plate and the middle block (thick plate).

Despite the fact that only ⊥ interfaces behavior has been evaluated using mechanical characterization, it is interesting to study the microstructure of both types of junctions as the coating thicknesses are not the same (§4.3.2).
### 4.4.2.1 // interface

Concerning // interfaces and according to Figure 40, the measurements show that the coating thicknesses of the involved parts are the thinner ones: 4.7 µm to 5.7 µm for the alloy 600 parts and 4.9 µm to 7.5 µm for the alloy 230 ones.

Three different zone types can be observed along alloy 600 // interfaces (Figure 46):

- **Zone type 1:** The coating is still visible with the three initial interfaces remaining between the alloy 600 and the coating on one hand and between the two coating layers on the other hand. Some grain migration can be observed without defects (remaining holes). The chemical analysis (EDS) shows that diffusion occurred but the chemical composition stays slightly different in the initial coating zone compared to the alloy 600.

- **Zone type 2:** Nearly identical to zone type 1 despite the fact that the interface between the two coating layers has disappeared. The chemical analysis (EDS) is similar to zone type 1.

- **Zone type 3:** Complete microstructural evolution without initial interfaces visible (small grains in the previous coating zone). However, the chemical analysis (EDS) is similar to zones types 1 and 2.

In all cases, a carbide free zone is observed on each side of the HIP junction compared to the base material (25 µm affected approximately).

<figure><img src="image_52.png" /><figcaption>Figure 46: Microstructural observations (SEM) and chemical analysis (EDS) of the interface between two alloy 600 thin plates (// interface) after HIP process.</figcaption></figure>

Using high magnitude SEM observations (Figure 47), precipitates can be seen on the old interfaces (Mg and Al rich oxides according to EDS analysis). These oxides are bigger and more numerous in zone type 1 compared to zone type 3. Their presence can explain the limitation of the grain boundary migration in zone types 1 and 2 as it was observed
on junction without coating (§4.2). However, no explanation has been found concerning these different behaviours along a // interface.

<figure><img src="image_53.png" /><figcaption>Figure 47: Microstructural observations (SEM) and chemical analysis (EDS) of particular zones of the interface between two alloy 600 thin plates (// interface) after HIP process.</figcaption></figure>

Concerning the alloy 230 // interface, only zone types 1 and 3 can be observed (Figure 48). In zone type 1, the remaining coating thickness is thinner compared to the same zone in the alloy 600 case. The chemical analysis (EDS) shows that diffusion occurred but the composition remains slightly different in the initial coating zone compared to the base material. In all cases, a carbide free zone is observed on each side of the HIP junction compared to the base material similarly to the alloy 600 case (25 µm affected approximately).

<figure><img src="image_54.png" /><figcaption>Figure 48: Microstructural observations (SEM) and chemical analysis (EDS) of the interface between two alloy 230 thin plates (// interface) after HIP process.</figcaption></figure>
High magnitude SEM observations (Figure 49) show that oxides block grain boundary migration as in alloy 600 case. These precipitates contain only Al and seem to block grain boundary migration as it was observed on direct junction (§4.2).

<figure><img src="image_55.png" /><figcaption>**Figure 49:** Microstructural observations (SEM) and chemical analysis (EDS) of particular zones of the interface between two alloy 230 thin plates (// interface) after HIP process.</figcaption></figure>

#### 4.4.2.2 ⊥ interface

Concerning the ⊥ interface, the one that is tested in the mechanical characterization, the observations indicate that the three different zones seen in the // interfaces are also present in alloy 600 mock-ups (Figure 50).

<figure><img src="image_56.png" /><figcaption>**Figure 50:** Microstructural observations (SEM) and chemical analysis (EDS) of the interface between a thin plate and a thick plate of alloy 600 (⊥ interface) after HIP process.</figcaption></figure>
As the coating thicknesses are more important for the surfaces involved in the ⊥ interfaces compared to the // ones, the total residual coating is more important for zone types 1 and 2. Consequently, the chemical composition difference between the initial coating center and base material is more important (EDS analysis, Figure 50).

For zone type 1, as the interface between the two coating layers is still visible, the initial difference in the coating thickness between the thick and the thin plates can be observed after HIP process. For zone type 3, the recrystallization is not as advanced as for // interfaces.

Concerning the alloy 230 mock-ups, the ⊥ interface microstructure is different from // interface one. Indeed, zone type 1 cannot be observed while zone type 2 are present (Figure 51). In both cases, zone type 3, showing total recrystallization, are observable.

Compared to alloy 600 mock-up case, the alloy 230 one does not show important chemical difference between the middle of the old coating and the base material (EDS analysis, Figure 51). However, the chemical spectra of Al indicate that aluminum rich precipitates exist in the interface zone. More precisely, these precipitates could be alumina located in the old junction between the two coatings (zone type 2) and at grain boundaries in the interface zone (zone types 2 and 3). More precise analyzes are needed to confirm it.

<figure><img src="image_57.png" /><figcaption>Figure 51: Microstructural observations (SEM) and chemical analysis (EDS) of the interface between a thin plate and a thick plate of alloy 230 (⊥ interface) after HIP process.</figcaption></figure>

## 4.5 CONCLUSIONS ON MICROSTRUCTURAL CHARACTERIZATION

Concerning base material microstructure, HIP process has an impact on the grain size for alloy 600 plates, more important for the thick plate compared to the thin one. The highly heterogeneous microstructure obtained could be a problem for mechanical characteristics. For alloy 230, the microstructural evolution observed for both plate types is more usual as the average grain size increases but without abnormal big grains.

Regarding diffusion bounded interfaces, preliminary examination of direct junctions between two plates of alloy 600 or alloy 230 did not show any grain boundary migration due to oxide precipitation at the interface. Consequently, a coating has been made on the HIP mock-up parts to promote the interface characteristics. However, this coating appeared to be thicker than the expected one. It led to a specific heterogeneous microstructure between the interface
zone and base material after HIP process without preventing all oxide precipitation. This phenomenon could have a
direct impact on the mechanical properties of the interfaces.

**5. MECHANICAL CHARACTERIZATION**

**5.1 RESEARCH DESIGN**

The tests are conducted at room temperature and at 870°C depending of the property evaluation. The temperature of 870°C has been chosen firstly to be close to the expected highest temperature for the solar receiver modules. This temperature has also been selected because it is close to 1600 degree Fahrenheit, a standard temperature for mechanical characterization in the literature. All the tests are conducted in air.

The mechanical testing campaign parameters are listed below. It has been done on samples with horizontal diffusion bounded interface and on base materials (samples without horizontal interface) for comparison (Figure 24). These tests have been established in accordance with literature data to compare the results ([600-1], [230]), so the parameters may vary from one alloy to the other. One can see that alloy 230 was studied under more severe conditions compared to alloy 600 due to its higher mechanical characteristics (creep and fatigue tests):

* **Tensile tests: (for alloys 230 and 600)**

* **Temperatures:**

* Room temperature,

* 870°C.

* **Strain rate:** $5 \cdot 10^{-4} \text{ s}^{-1}$

* **Charpy V impact tests: (for alloys 230 and 600)**

* **Temperature:** Room temperature.

* **Creep tests:**

* **Temperature:** 870°C,

* **Stresses:**

*Alloy 230*

* 70MPa,

* 60MPa,

* 50MPa.

*Alloy 600*

* 22MPa,

* 20MPa,

* 18MPa.

* **Fatigue tests:**

* **Temperatures:**

* Room temperature,

* 870°C.

* **Strain amplitude:**

*Alloy 230*

* Room temperature tests:

* ± 0.5%,

* ± 0.4%,

* ± 0.3%.

* 870°C:

* ± 0.25%,

* ± 0.20%,

* ± 0.15%.
Alloy 600

* Room temperature tests:

* ± 0.4%,

* ± 0.3%,

* ± 0.2%.

* 870°C:

* ± 0.2%,

* ± 0.15%,

* ± 0.1%.

# 5.2 EXPERIMENTAL PROCEDURE

## 5.2.1 Tensile tests

Tensile tests are made on electromechanical testing machines: an ADAMEL DY36 machine for room temperature tests and a 20M MTS machine equipped with a 1400°C AET furnace for high temperature tests. The load cells used have a capacity of 20 kN and the tests are piloted with MTS TestWorks software. Clip on extensometers are used to measure calibrated zone deformation during tests (extracted after 20 % of deformation). Test samples are machined according to the standard NF EN ISO 6892-1 and 6892-2. Tensile sample drawings can be seen in Annex 4. The tensile curves are plotted using the engineer stress σ and strain ε, i.e. $\sigma = \frac{F}{S_0}$ with F the recorded force and S₀ the initial section of the samples and $\epsilon = \frac{L-L_0}{L_0}$. 100, with L the recorded displacement and L₀, the initial gage length of the sample.

## 5.2.2 Charpy V notch impact tests

Charpy tests are conducted on a Zwich/Roell pendulum impact tester with a maximum capacity of 300 J. A numerical recorder allows obtaining a friction compensation on the impact energy. Tests are conducted according to EN ISO 148-1. Charpy V notch impact sample drawings can be seen in Annex 4. The V-notch of half of the samples has been machined on one of the interfaces, the other ones have been machined on the other interface (Figure 24).

## 5.2.3 Creep tests

Creep tests are done on constant load (dead loading) on MAYES machines with a maximum capacity of 20 kN equipped with 1000°C resistive furnaces. Three thermocouples are fixed on the top, in the middle and at the bottom of the calibrated zone of the samples to maintain a stable temperature (gradient of ± 3°C, which is the uncertainty of the K-type thermocouples). LVDT displacement transducers fixed on the gage length helps to record live deformation. Test samples are machined according to the standard NF EN ISO 204. Creep sample drawings can be seen in Annex 4. The creep stress imposed is calculated using the formula: $\sigma = \frac{F}{S_0}$ with F the applied force and S₀ the initial section of the samples. The curves are plotted using the engineer strain ε, i.e. $\epsilon = \frac{L-L_0}{L_0}$. 100, with L the recorded displacement and L₀, the initial gage length of the sample.

## 5.2.4 Fatigue tests

Low cycle fatigue tests were conducted on a hydraulic dynamic MTS machine (maximum capacity: 100 kN, maximum frequency: 60 Hz). MTS quartz rod extensometer fixed on the gage length helps to pilot the tests. The machine is equipped with a 1000°C MTS resistive furnace. Test samples are machined according to the standard ISO 12106. Fatigue sample drawings can be seen on Annex 4. The fatigue curves are plotted using the engineer stress σ, i.e. $\sigma = \frac{F}{S_0}$ with F the recorded force and S₀ the initial section of the samples. Tests have been conducted to rupture if the number of cycles to rupture is under 100,000 cycles or stopped if the sample does not break until it reaches this limit.

# 5.3 MECHANICAL TESTS RESULTS

The mechanical test results done on the alloys 600 and 230 HIP mock-ups are discussed in the following paragraphs. The major data extracted from these tests are reported in annexes: Annex 5 for tensile data, Annex 6 for Charpy V-notch impact data, Annex 7 for creep data and Annex 8 for fatigue data.
### 5.3.1 Tensile properties

#### 5.3.1.1 Room temperature tests

The room temperature tensile curves of the tests conducted on alloy 600 mock-ups (base material, one interface and two interfaces) have been plotted in a graph exposed on Figure 52. One can easily see that there is no important difference between the three mock-up types: an average ultimate tensile strength from 691MPa to 695MPa and an elongation to rupture from 35.8 % to 38.6 %. This similar tensile behavior is due to the fact that the weak point of the assembly is located in the vertical plates (thin plates) as shown on the gage length of the samples after tests on the Figure 53. Just the 0.2 % yield strength varies depending to the mock-up type. It is nearly the same for base material and for one interface (265 MPa and 274 MPa respectively) whereas it reaches 309 MPa for two interfaces. This phenomenon is related to the fact that the extensometer used to measure the elongation in the beginning of the tests is located in the middle of the samples and recorded only the thick plate deformation in the two interfaces samples. Consequently, it appears that the thick plate is stiffer in its previous thickness direction than the thin ones in the rolling direction.

<figure><img src="image_58.png" /><figcaption>Figure 52: Tensile curves obtain during tests at room temperature on alloy 600 mock-ups (base material, one interface and two interfaces) after HIP process.</figcaption></figure>

<figure><img src="image_59.png" /><figcaption>Figure 53: Gage length, fracture surface observation of tensile samples after room temperature test extracted from base material and interface alloy 600 mock-ups.</figcaption></figure>

The diffusion bounded interfaces can also be located visually on the gage length surface of the tensile samples after test, as shown on Figure 53. This phenomenon is due to an enhanced plastic deformation of the remaining coating and the carbide free zone in the base material.
The alloy 230 room temperature tensile behaviour is different, depending on the mock-up type (base material or interface mock-ups). Indeed, the curves plotted on Figure 54 show that the thick plate exhibit reduced properties (0.2 % yield strength and elongation to rupture) than the thin plate base material (green and red curves compared to the blue ones). That's why the rupture occurred in this part of the interface mock-ups (Figure 55). It can be related to the fact that the alloy 230 thick plate is tested in its previous thickness direction compared to the thin ones tested in the rolling direction which exhibits reduced tensile properties. This phenomenon cannot be anticipated as the thickness direction is not mechanically tested by the alloy manufacturers (Annex 3). However, one can notice that the rupture does not occur at the interface for both alloys presenting HIP junctions.

<figure><img src="image_60.png" /><figcaption>Figure 54: Tensile curves obtain during tests at room temperature on alloy 230 mock-ups (base material, one interface and two interfaces) after HIP process.</figcaption></figure>

<figure><img src="image_61.png" /><figcaption>Figure 55: Gage length, fracture surface observation of tensile samples after room temperature test extracted from base material and interface alloy 230 mock-ups.</figcaption></figure>

As expected, alloy 230 HIP treated base material exhibits higher 0.2 % yield and ultimate tensile strengths with the same elongation to rupture than alloy 600. For interface assemblies, alloy 230 samples also exhibit higher 0.2 % yield and tensile strengths than interfaces for alloy 600 but reduced elongation to rupture (impact of thick plate properties).

### 5.3.1.2 High temperature tensile tests

The comparison of the high temperature tensile curves obtained on alloy 600 base material (Figure 56) and alloy 230 one (Figure 57) shows that the latter exhibit very higher properties (0.2 % yield and ultimate tensile strengths) for the
same elongation to rupture. The average 0.2 % yield strengths of HIP treated base materials compared to literature data (Figure 3) are very similar (96.5 MPa compared to 100 MPa for alloy 600 and 238.3 MPa compared to 242 MPa for alloy 230). However, the elongation to rupture is reduced (62.5 % compared to 88 % for alloy 600 and 63 % compared to 99.5 % for alloy 230). The precipitation of carbides during the HIP cooling phase could explain this difference (high temperature treatment + rapid quench done on reference material to prevent precipitation).

However, although interfaces are not the weak point of HIP assemblies at room temperature, unfortunately, this is the case during high temperature examinations. This phenomenon is visible for alloy 600 assemblies (Figure 56) with samples that show a highly reduced elongation to rupture compared to the base material but with a comparable elastic phase and 0.2% yield strength. It is more marked for alloy 230 (Figure 57) as the samples with interfaces breaks during the elastic domain (Figure 58). The curve slope for alloy 230 interface samples is not the same compared to base material ones due to a problem of extensometer record. The elongation for these samples corresponds to the total machine deformation reported to the sample gage length.

<figure><img src="image_62.png" /><figcaption>Figure 56: Tensile curves obtain during tests at 870°C on alloy 600 mock-ups (base material and two interfaces) after HIP process.</figcaption></figure>

<figure><img src="image_63.png" /><figcaption>Figure 57: Tensile curves obtain during tests at 870°C on alloy 230 mock-ups (base material and two interfaces) after HIP process.</figcaption></figure>
<figure><img src="image_64.png" /><figcaption>Figure 58: Close view of the tensile curves obtain during tests at 870°C on alloy 230 interface mock-up after HIP process.</figcaption></figure>

The observation of the samples after high temperature tensile tests (Figure 59) shows that both base material alloys exhibit an important reduction in area in the rupture zone, more important for alloy 600 compared to the other one. Concerning interface samples, the pictures show that the rupture occurred in one of the interface zones for both alloys (flat fracture surfaces).

<figure><img src="image_65.png" /><figcaption>Figure 59: Gage length and fracture surface observation of tensile samples after 870°C test extracted from base material and interface mock-ups for both alloys, 600 and 230.</figcaption></figure>

However, observing more precisely the fracture surface of 870°C tensile samples extracted from interface mock-ups, micro ductility is visible for both alloys as shown in Figure 60. The 3D measurements indicate that most of the fracture occurred in the middle of the HIP junction (in the old coating, blue colour on right images, Figure 60) but also from either side of this coating (red and purple colours on right images, Figure 60).
<figure><img src="image_66.png" /><figcaption>Alloy 230 interface mock-up: fracture surface of 870°C tensile sample</figcaption></figure>

<figure><img src="image_67.png" /></figure>

**Figure 60: Close observation of 870°C tensile sample fracture surfaces from alloy 600 and alloy 230 interface mock-ups (OM).**

As expected, alloy 230 HIP treated base material exhibits higher 0.2% yield and ultimate tensile strengths with the same elongation to rupture at high temperature than alloy 600. For interface assemblies, premature rupture happens at low strain for both alloys. The rupture is observed after a plastic deformation for alloy 600 interface mock-ups while it occurs during the elastic domain for alloy 230 but at higher stress level (140 to 200 MPa for alloy 230 compared to 101 to 103 MPa for alloy 600).

### 5.3.2 Charpy V-notch impact strength

The Charpy V-notch impact strength of the HIP treated base material and interface mock-ups for alloys 600 and 230 are presented on Figure 61 and Figure 62 respectively.

For the base material, the results obtained for the alloy 600 are above 244J, which is the reference energy that can be found in the literature [600-1]. However, this is not the case for alloy 230 base material, which exhibits an energy value below the reference one (average of 65J compared to 75J, [230]).

Testing the diffusion bounded interfaces leads to an important reduction in both alloys Charpy V-notch impact toughness. Indeed, Figure 61 and Figure 62 show a reduction factor of 2.6 and 2.5 compared to base material for alloys 600 and 230 respectively. However, the observation of the fracture surface of the interface samples shows important roughness and non-negligible lateral deformation, which implies that the damage propagation does not seem to occur only in the interface. Such a reduction in Charpy V-notch toughness has been observed previously for other HIP assembled materials when it is compared to base materials (CEA feedback).
<figure><img src="image_68.png" /><figcaption>Figure 61: Charpy V-notch impact strength of alloy 600 base material and interface after HIP process, comparison with literature [600-1].</figcaption></figure>

<figure><img src="image_69.png" /><figcaption>Figure 62: Charpy V-notch impact strength of alloy 230 base material and interface after HIP process, comparison with literature [230].</figcaption></figure>

### 5.3.3 Creep properties

The curves obtained during the creep tests done at 870°C on the base material and interfaces alloy 600 mock-ups are presented on Figure 63. A close view of the first 60 h of test is reported on Figure 64. All the tests have been conducted to sample rupture.

Concerning the base material, the alloy 600 has a conventional creep behavior with a very short primary stage within the first hours (diminution of the deformation rate), a short secondary stage in the first 100 h (constant deformation rate) and then a long third stage corresponding to the damage stage leading to the rupture at high strain (over 45%).
Compared to the base material, the interface samples show a highly reduced lifetime (less than 55 hours, Figure 64). The secondary creep stage is short for all the samples and the minimum creep rate during this stage is higher than base material (from x1.3 to x2 depending on the imposed stress, Annex 7). The tertiary creep stage is very short for interface mock-ups leading to a quick rupture at very low total sample strain (less than 1.5 %).

<figure><img src="image_70.png" /><figcaption>Figure 63: Creep curves obtain during tests at 870°C on alloy 600 mock-ups (base material and two interfaces) after HIP process.</figcaption></figure>

<figure><img src="image_71.png" /><figcaption>Figure 64: Close view of the beginning of the creep curves obtain during tests at 870°C on alloy 600 mock-ups (base material and two interfaces) after HIP process.</figcaption></figure>

The curves obtained during the creep tests done at 870°C on the base material and interfaces alloy 230 mock-ups are presented on Figure 65. A close view of the first 2 h of test is reported on Figure 66. All the tests on base material have been interrupted after 670 h (to prevent too long test duration) and on interface samples until rupture.

Alloy 230 base material primary creep stage is short (less than an hour, Figure 66) but contrary to alloy 600, the secondary stage lasts several thousands of hours (425 h under 70 MPa and is not ended at lower stresses tested when the tests stopped).
For alloy 230 interface mock-ups, data have only been recorded during tests made under 50MPa, because the samples tested under higher stresses have broken during the loading phase. However, the tests conducted under 50 MPa do not last more than 1.5 h with comparable curve than base material tested under the same condition until a brutal rupture without tertiary stage.

<figure><img src="image_72.png" /><figcaption>Figure 65: Creep curves obtain during tests at 870°C on alloy 230 mock-ups (base material and two interfaces) after HIP process.</figcaption></figure>

<figure><img src="image_73.png" /><figcaption>Figure 66: Close view of the beginning of the creep curves obtain during tests at 870°C on alloy 230 mock-ups (base material and two interfaces) after HIP process.</figcaption></figure>

Observing the gage length and the fracture surface of the alloy 600 samples (Figure 67), base material shows conventional rupture with secondary cracks visible on the surface of the gage length. For interface samples, the rupture happens in a zone near the diffusion bounded junctions. For alloy 230 samples, as the base material samples have just begun the tertiary stage or are still in the secondary one, no sign of damage is observed on the gage length (Figure 68). However, the rupture happens near the junction zones for interface samples as for alloy 600.
<figure><img src="image_74.png" /><figcaption>Figure 67: Gage length and fracture surface observation of creep samples after 870°C test extracted from base material and interface mock-ups for alloy 600.</figcaption></figure>

<figure><img src="image_75.png" /><figcaption>Figure 68: Gage length and fracture surface observation of creep samples after 870°C test extracted from base material and interface mock-ups for alloy 230.</figcaption></figure>
Using the base material data, one can interpolate the strain-stress curves obtain after 100 h during the creep tests to obtain the stress to produce 1 % creep in 100 h (Figure 69, left graph). The results obtained on base materials are very similar to the literature creep data [600-1] and [230] (Figure 69, right graph). Consequently, HIP process does not seem to modify the base material creep properties. Once again, the alloy 230 creep performance is highly better compared to the reference alloy 600.

<figure><img src="image_76.png" /><figcaption>Figure 69: Strain-stress data obtained after 100h during the creep tests on alloys 600 and 230 base material after HIP process and comparison of test results with literature data [600-1], [230].</figcaption></figure>

### 5.3.4 Fatigue properties

#### 5.3.4.1 Fatigue cycle to failure

The first fatigue results to investigate are the number of cycles to rupture. The records obtained in this project on base material at room temperature are compared with literature data on Figure 70.

<figure><img src="image_77.png" /><figcaption>Figure 70: Comparison of room temperature fatigue test results on alloys 600 and 230 base material with literature data [600-1], [230].</figcaption></figure>

One can observe that as the lower total strain range tests of this campaign (0.4 % for alloy 600 and 0.6 % for alloy 230) have all been stopped after 100,000 cycles and do not show signs of damage, the results obtained show better behaviours than the reference ones.
Comparing the two mock-up types at room temperature (Figure 71), it appears that the interface samples show much reduced cycle to failure for both alloys than base materials. However, the observation of the samples after tests indicates that the failure does not occur at the HIP junctions but in the thick plate (except for the 1 % total strain range tests on alloy 230, Figure 72). The microstructural structure inherited from the plate manufacturing processes is responsible for this phenomenon.

<figure><img src="image_78.png" /><figcaption>Figure 71: Comparison of room temperature fatigue behavior of alloys 600 and 230 base material and interface mock-up.</figcaption></figure>

<figure><img src="image_79.png" /><figcaption>Figure 72: Gage length and fracture surface observation of fatigue samples after room temperature test extracted from base material and interface mock-ups for alloy 600 on the left and alloy 230 on the right.</figcaption></figure>
Finally, alloy 230 shows a better lifetime than alloy 600 for a same total strain range (except for 0.8 % interface sample) due to its higher yield strength at room temperature leading to lower plastic residual strain in each cycle (example on Figure 73).

<figure><img src="image_80.png" /><figcaption>Figure 73: Comparison of the cycle 100 recorded during fatigue tests at room temperature with a total strain range of 0.4 % for alloys 600 and 230.</figcaption></figure>

The fatigue performance of both alloys base materials at elevated temperature is shown on Figure 74. The results indicate clearly the enhanced behaviour concerning cycles to rupture for the alloy 230 compared to the reference alloy 600. As at room temperature, alloy 230 shows a better lifetime than alloy 600 for a same total strain) due to its higher yield strength at 870°C leading to lower plastic residual strain in each cycle.

<figure><img src="image_81.png" /><figcaption>Figure 74: Fatigue test results at 870°C done on alloys 600 and 230 base material.</figcaption></figure>

The 870°C fatigue test results of the HIP treated alloy 230 base material are over the data found in the literature (Figure 75). For alloy 600, it is not possible to compare the project results with previous ones as this alloy is used at lower temperature if it sustains mechanical stress.
<figure><img src="image_82.png" /><figcaption>Figure 75: Comparison of fatigue test results done at 870°C on alloy 230 base material with literature data [230].</figcaption></figure>

As 870°C tensile tests show that the rupture occurred at very low strain for interface mock-ups (see §5.3.1.2), it would be difficult to make fatigue tests in this condition or to interpret the results. Consequently, it has been decided not to make high temperature fatigue tests at 870°C on interface samples.

#### 5.3.4.2 Stress evolution during tests

The maximum stress and minimum stress (absolute value) per cycle obtained during room temperature fatigue tests have been plotted on Figure 76 for alloy 600 and on Figure 77 for alloy 230 (base material and interface mock-ups). For all tests, both alloys show a hardening phase (during the first 60 cycles for alloy 600 and 80 cycles for alloy 230). Then the behaviour depends on the total strain range. For the lower one (0.4 for alloy 600 and 0.6 for alloy 230), the stress is nearly stable until the beginning of the sample damage of the test stop. For higher total strain range, a softening phase occurred until the sample damage leading to rupture. This phenomenon is usual for this type of solid solution hardening Nickel-based alloys.

Comparing base material and interface tests, the results show that the second ones exhibit generally lower maximum and minimum stresses than the first ones. Once again, these data indicate that the thick plates have lower mechanical properties in the direction solicited (thickness direction) than the thin plates rolling direction. This comportment is almost true when the total strain range increases.

<figure><img src="image_83.png" /><figcaption>Figure 76: Evolution of the maximum stress and the minimum stress (absolute value) recorded during room temperature fatigue tests done on alloy 600 base material and interface mock-up.</figcaption></figure>
<figure><img src="image_84.png" /><figcaption>Figure 77: Evolution of the maximum stress and the minimum stress (absolute value) recorded during room temperature fatigue tests done on alloy 230 base material and interface mock-up.</figcaption></figure>

The maximum stress and minimum stress (absolute value) per cycle obtained during 870°C fatigue tests on base materials have been plotted on Figure 78 for alloy 600 and on Figure 79 for alloy 230. Compared to room temperature, the high temperature performance of both alloys is different except for the lower total strain range (no stress variation during the tests until sample damage at 0.2 % for alloy 600 and 0.3 % for alloy 230).

For alloy 600, no hardening phase is observed whatever the total strain range tested while the other alloy keeps a small one until 70 cycles approximately. Then a softening phase happens for the higher total strain range tested. Low difference in the stress level appears in these conditions.

Concerning the alloy 230, a hardening phase is still visible until 70 cycles approximately as at room temperature followed by a stress stabilization until the sample damage. Once again, the alloy 230 shows better properties at high temperature compared to alloy 600.

<figure><img src="image_85.png" /><figcaption>Figure 78: Evolution of the maximum stress and the minimum stress (absolute value) recorded during fatigue tests done at 870°C on alloy 600 base material.</figcaption></figure>
<figure><img src="image_86.png" /><figcaption>Figure 79: Evolution of the maximum stress and the minimum stress (absolute value) recorded during fatigue tests done at 870°C on alloy 230 base material.</figcaption></figure>

## 5.4 CONCLUSIONS ON MICROSTRUCTURAL AND MECHANICAL CHARACTERIZATIONS

As the HIP process is done at high temperature, it affects the base material microstructure. For alloy 600, the behaviour depends on the plate supply with abnormal grain growth for the thick one compared to a more homogeneous grain growth for the thin one. Alloy 230 exhibits a more conventional regular grain growth for all the plates supplied.

Concerning HIP junctions, because of a more important coating thickness than the expected one, particular microstructures can be observed in the interface zones for both alloys. An oxide precipitation and uncompleted elemental diffusion leading to chemical composition differences in this zone limit grain boundaries to cross entirely the interface. The disappearance of carbides in base material near the junction is also observed. However, diffusion bounding operates all along the interfaces.

Regarding mechanical characterization at room and high temperatures (870°C), HIP treated base material for both alloys exhibit good properties in tensile, Charpy V-notch toughness, creep and fatigue. The obtained characteristics are comparable to literature data on as received materials and show the enhanced behaviour of the alloy 230 than the reference one, the alloy 600.

Mechanical tests done on samples extracted from interface mock-ups indicate that the performances are more or less reduced at room temperature but drastically fail at 870°C. The reduced room temperature properties seem to be due to the fact that the intermediate thick plates constituting the interface assemblies show low properties in its thickness direction compared to the rolling one of the thin plates. The HIP junctions do not seem to be involved in the damage in most of the cases in this condition. However, it becomes the weak point of the assemblies at high temperature for both alloys. The microstructure and chemical differences of the interface zone compared to the base material would cause important differences of local mechanical characteristics, which causes premature sample rupture.

One must consider that choosing a stronger Ni-based alloy to manufacture the solar receiver is motivated to enhance the manifold's characteristics (pressurized air at high temperature) but also the active part ones (stresses due to thermal expansion of the inner copper parts). However, the stresses have not been evaluated precisely. Detailed thermomechanical simulations (assembly process and in operation) are necessary to do so but have not been planned in the POLYPHEM project.
## 5.5 SOLUTIONS TO ENHANCE NI-BASED ALLOY INTERFACES AFTER HIP PROCESS

### 5.5.1 Modification of the interface design

The first solution would consist in an evolution of the interface design to sustain high temperature mechanical solicitations. For example, replacing flat interfaces with a dovetail could be an interesting modification (Figure 80). Using this modification will enhance the properties of the interface with a mechanical anchor. However, several negative points appear. Firstly, this type of modification imposes to keep sufficient Ni-based alloy thickness all around the solar receiver modules after manufacturing. No machining of the outer surface of the solar receiver modules is possible after the HIP process. Secondly, this modification will make the assembly of the module parts more complicating. Thirdly, this solution cannot be employed for all the interfaces to make the assembly possible. Finally, making the dovetails will increase the machining cost of the receiver.

<figure><img src="image_87.png" /><figcaption>Figure 80: Example of modified interface shape between to Ni-based alloy part in solar receivers: initial flat interface on the left, dovetail shape interface on the right.</figcaption></figure>

### 5.5.2 Full penetration welding of the interfaces

Another solution to enhance the mechanical properties of the Ni-based part interfaces consists in making full penetration welding between these parts (conventional solution). This could be done using TIG welding, laser welding or other conventional welding technics. This solution is illustrated on Figure 81.

<figure><img src="image_88.png" /><figcaption>Figure 81: Example of modified interface shape between to Ni-based alloy part in solar receivers: initial flat interface on the left, full penetration-welding interface on the right.</figcaption></figure>

With this alternative solution, the principal goal of the HIP process made on the solar receiver modules will be to make the diffusion bonding of the interfaces between the copper parts themselves and between the copper part and the Ni-based ones. Another advantage making this high temperature process will be to treat the welding beads and the thermal affected zones. This will generate a softening of these regions with normally a beneficial recrystallization.

However, this solution implies to make most of the welding without the copper part inside the modules. This implies to be careful to the deformations due to this previous step in order to not hind the following assembly. Only final closure of the modules before the HIP step will be made with all the parts assembled. This final operation must be made carefully in order not to melt copper parts (welding embrittlement).
### 5.5.3 Selected solution

According to the previous description of the alternative manufacturing solutions, it seems that the full penetration welding of the Ni-based part interfaces would be the best one. All the manufacturing step details will be described at the end of the task 1.2.

## 6. CONCLUSIONS ON SOLAR RECEIVER MATERIAL INVESTIGATION

The benchmark concerning the potential alloy used for manufacturing the solar receiver module part in contact with high temperature air leads to the selection of the Nickel-based alloy 230. However, the reference alloy 600 employed for making previous solar receiver is also well ranked. Optical properties evaluation in real conditions does not change the results. Complementary investigations have started on samples coated with a potential enhancing optical property procedure. The exploitation of these tests and the measurements of optical properties at high temperature will be completed until the end of year 2020.

Alloys 230 and 600 have been used to manufacture HIP mock-ups to evaluate and compare the mechanical properties of base material and diffusion bonded junctions.

Microstructural and mechanical characterizations show better properties for HIP treated base material alloy 230 compared to alloy 600, the reference alloy previously used for solar receiver manufacturing. However, even if the diffusion bounded interfaces have good behavior at room temperature, the high temperature mechanical characteristics are very low, and the rupture happened in these zones. Consequently, flat diffusion bounded junctions cannot be used directly to manufacture the solar receiver modules using the actual HIP manufacturing process.

Full penetration welding between Ni-based parts would be implemented in the solar receiver module manufacturing steps to enhance mechanical properties. All the details will be described at the end of task 1.2.
<figure><img src="image_89.png" /><figcaption>Annex 1: Material certificates of alloys 230, 600, 617, X and HR-120 used for optical tests in CNRS facilities.</figcaption></figure>

<figure><img src="image_90.png" /></figure>
Alloy 617

A 00439785891

P.82

<figure><img src="image_91.png" /></figure>

SPECIAL
METALS

SPECIAL METALS WIGGIN LIMITED

Holmer Road, Hereford, England HR4 9SL
Tel: +44 (0)1432 382200 Fax: +44 (0)1432 284030
Reg. In England No. 36721

INSPECTION CERTIFICATE / CERTIFICAT DE RÉCEPTION

Quality System Compliance >

EN 10204:2004 + 3.1

ISO 9001:2000 + AFAG

ISO/TS 18945 by agreement - AFAG

CAA (02, 04) Approval No. A42230/047

TÜV Approval to AD - Merkblatt WD/TRD 100

NAS0001:SAE1 Approval No. 1906

For tests performed by IncoTest >

ISO/IEC 17025 - UKAS, CAA (04)

Customer / Client

SPECIAL METALS SERVICES SA

17 RUE DES FRERES LUMIERE

69880 CHASSIEU

FRANCE

<figure><img src="image_92.png" /></figure>

<figure><img src="image_93.png" /></figure>

<figure><img src="image_94.png" /></figure>

Certificate No. /
Certificat No.

1265531

Dated / Date 25/02/2006

Page No. 1 of 2

Consignée / Adresse pour l'évaluer

SPECIAL METALS SERVICES SA

17 RUE DES FRERES LUMIERE

69680 CHASSIEU

FRANCE

CONSIGNEE WITH GOODS

Customer's Order No. / Contract No.
No. de la Commande / Contrat du Client

101821

Inspector

H42

Product Description & Dimensions / Descriptions et Dimensions du Matériel

INCONEL alloy 617, Hot Finished Round, Machined, Solution Annealed,
50 DIA X 2000 MM CUT

Our Reference No.

Quantity

Weight or Length

Cost No.

Incoming Certificate No.
Certificat Original No.

Advice Note
Ban de l'évaluer
A61197

Notre de référence / Reference
NTN0544/01

Specifications:

SAE AMS 5887 ISS B UNS N06617

Chemical Composition / Composition Chimique

Weight % (except where stated ppm) / Poids % (selon invention en ppm)

<table><thead><tr><th></th><th>C</th><th>Si</th><th>Mn</th><th>P</th><th>S</th><th>Al</th><th>B</th><th>Co</th><th>Cr</th></tr></thead><tbody><tr><td>Btm</td><td>0.06</td><td>0.11</td><td>0.12</td><td>&lt;0.005</td><td>&lt;0.001</td><td>0.89</td><td>&lt;0.001</td><td>12.10</td><td>21.13</td></tr><tr><td>Top</td><td>0.058</td><td>0.06</td><td>0.12</td><td>&lt;0.005</td><td>&lt;0.001</td><td>0.95</td><td>&lt;0.001</td><td>12.20</td><td>21.53</td></tr><tr><td>Max</td><td>0.15</td><td>0.50</td><td>0.50</td><td>0.015</td><td>0.015</td><td>1.50</td><td>0.006</td><td>15.00</td><td>24.00</td></tr><tr><td>Min</td><td>0.05</td><td></td><td></td><td></td><td></td><td>0.80</td><td></td><td>10.00</td><td>20.00</td></tr><tr><td></td><td>Cu</td><td>Fe</td><td>Mo</td><td>Ni</td><td>Ti</td><td></td><td></td><td></td><td></td></tr><tr><td>Btm</td><td>0.01</td><td>0.29</td><td>9.09</td><td>Bal</td><td>0.41</td><td></td><td></td><td></td><td></td></tr><tr><td>Top</td><td>0.01</td><td>0.28</td><td>9.33</td><td>Bal</td><td>0.41</td><td></td><td></td><td></td><td></td></tr><tr><td>Max</td><td>0.50</td><td>3.00</td><td>10.00</td><td>Balance</td><td>0.60</td><td></td><td></td><td></td><td></td></tr><tr><td>Min</td><td></td><td></td><td>8.00</td><td></td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>

Test Report No. / Report d'Essais No.
734397A

Mechanical Tests / Essais Mécaniques

<table><thead><tr><th>Test</th><th>Temp.</th><th>0.2% PS</th><th>Ten. Str.</th><th>% Elong.</th></tr><tr><th>Report No.</th><th>°C</th><th>MPa</th><th>MPa</th><th>on 4D</th></tr></thead><tbody><tr><td>734397A</td><td>20</td><td>291</td><td>723</td><td>66.9</td></tr><tr><td>734397A</td><td>538</td><td>212</td><td>581</td><td>70.7</td></tr></tbody></table>

Creep Tests / Essais de Pluage

<table><thead><tr><th>Test</th><th>Stress</th><th>Temp.</th><th>LIFE h</th><th>% Elong.</th></tr><tr><th>Report No.</th><th>MPa</th><th>°C</th><th>Rupture</th><th>on 4D</th></tr></thead><tbody><tr><td>734397A</td><td>90</td><td>071</td><td>41.3</td><td>74.4</td></tr><tr><td>734397A</td><td>Incremental</td><td>loading</td><td>was employed.</td><td></td></tr></tbody></table>

Heat treatment / Traitement Thermique

Batch & test pieces: 63M 1175 C AC

Certificate continued / Certificate continuation

Certificat confon. /

K3000 13354

SPECIAL METALS /

M4847

S.A.

Quench invrée: 120

Signature:

<figure><img src="image_95.png" /></figure>

Date: 10.9.05

Ug

A0172940010025

BRIGHTRAY, CORRIGEL, FEARY, INCOCLAD, INCOLOY, INCONEL, INCOTHERM, INCO-WELD, KOTHERM.
MAXORB, MONEL, NILO, NILOMAG, NIMONIC, NIOTHERM, NI-SPAN, UDIMFT A WINCH on Trade Marte et Resserl Metale Pessentives.
<figure><img src="image_96.png" /></figure>

<figure><img src="image_97.png" /></figure>
<table><caption>Annex 2: Detailed benchmark ranking results for each type of properties
Table 12: Benchmark alloys' score concerning physical properties</caption><thead><tr><th rowspan="2">Rank points</th><th rowspan="2">Physical characteristic</th><th colspan="2">High temperature oxidation</th><th colspan="2">High temperature nitridation</th><th colspan="2">Thermal conductivity</th><th colspan="2">Thermal expansion</th></tr><tr><th colspan="2">6</th><th colspan="2">1</th><th colspan="2">3</th><th colspan="2">2</th></tr><tr><th></th><th>Property weighting</th><th>Alloy</th><th>Score</th><th>Alloy</th><th>Score</th><th>Alloy</th><th>Score</th><th>Alloy</th><th>Score</th></tr></thead><tbody><tr><td>12</td><td rowspan="10">Alloys classification</td><td></td><td></td><td></td><td></td><td>214</td><td>36</td><td>230</td><td>24</td></tr><tr><td>11</td><td></td><td></td><td></td><td></td><td>600</td><td>33</td><td>617</td><td>22</td></tr><tr><td>10</td><td></td><td></td><td></td><td></td><td>690</td><td>30</td><td>X</td><td>20</td></tr><tr><td>9</td><td></td><td>214</td><td>54</td><td></td><td></td><td>617</td><td>27</td><td>600</td><td>18</td></tr><tr><td>8</td><td></td><td>230</td><td>48</td><td></td><td></td><td>HR-160</td><td>24</td><td>602 CA</td><td>16</td></tr><tr><td>7</td><td></td><td>X</td><td>42</td><td>214</td><td>7</td><td>800H</td><td>21</td><td>601</td><td>14</td></tr><tr><td>6</td><td></td><td>617</td><td>36</td><td>600</td><td>6</td><td>X</td><td>18</td><td>690</td><td>12</td></tr><tr><td>5</td><td></td><td>HR-120</td><td>30</td><td>230</td><td>5</td><td>230</td><td>15</td><td>HR-160</td><td>10</td></tr><tr><td>4</td><td></td><td>600</td><td>24</td><td>617</td><td>4</td><td>HR-120</td><td>12</td><td>214</td><td>8</td></tr><tr><td>3</td><td></td><td>HR-160</td><td>18</td><td>X</td><td>3</td><td>602 CA</td><td>9</td><td>HR-120</td><td>6</td></tr><tr><td>2</td><td></td><td>601</td><td>12</td><td>330</td><td>2</td><td>330</td><td>6</td><td>330</td><td>4</td></tr><tr><td>1</td><td></td><td>800H</td><td>6</td><td>601</td><td>1</td><td>601</td><td>3</td><td>800H</td><td>2</td></tr></tbody></table>
<table><caption>Table 13: Benchmark alloys' score concerning thermomechanical properties</caption><thead><tr><th rowspan="3">Rank points</th><th rowspan="3">Mechanical characteristic</th><th colspan="2">YS at 0.2% offset</th><th colspan="2">Elongation</th><th colspan="2">Fatigue</th><th colspan="6">Creep (stress to obtain 1% of deformation)</th></tr><tr><th colspan="2">Property weighting</th><th colspan="2">Property weighting</th><th colspan="2">Property weighting</th><th colspan="2">Property weighting</th><th colspan="2">Property weighting</th><th colspan="2">Property weighting</th></tr><tr><th>Alloy</th><th>Score</th><th>Alloy</th><th>Score</th><th>Alloy</th><th>Score</th><th>Alloy</th><th>Score</th><th>Alloy</th><th>Score</th><th>Alloy</th><th>Score</th></tr></thead><tbody><tr><td>12</td><td rowspan="10">Alloys classification</td><td>214</td><td>60</td><td>230</td><td>48</td><td></td><td></td><td>617</td><td>12</td><td>617</td><td>12</td><td>617</td><td>36</td></tr><tr><td>11</td><td>230</td><td>55</td><td>617</td><td>44</td><td></td><td></td><td>214</td><td>11</td><td>214</td><td>11</td><td>HR-120</td><td>33</td></tr><tr><td>10</td><td>617</td><td>50</td><td>690</td><td>40</td><td></td><td></td><td>230</td><td>10</td><td>230</td><td>10</td><td>230</td><td>30</td></tr><tr><td>9</td><td>X</td><td>45</td><td>600</td><td>36</td><td></td><td></td><td>X</td><td>9</td><td>800H</td><td>9</td><td>800H</td><td>27</td></tr><tr><td>8</td><td>HR-120</td><td>40</td><td>800H</td><td>32</td><td></td><td></td><td>800H</td><td>8</td><td>X</td><td>8</td><td>214</td><td>24</td></tr><tr><td>7</td><td>690</td><td>35</td><td>HR-160</td><td>28</td><td>617</td><td>45</td><td>601</td><td>7</td><td>601</td><td>7</td><td>X</td><td>21</td></tr><tr><td>6</td><td>HR-160</td><td>30</td><td>601</td><td>24</td><td>230</td><td>40</td><td>HR-160</td><td>6</td><td>HR-160</td><td>6</td><td>HR-160</td><td>18</td></tr><tr><td>5</td><td>600</td><td>25</td><td>X</td><td>20</td><td>X</td><td>35</td><td>600</td><td>5</td><td>600</td><td>5</td><td>601</td><td>15</td></tr><tr><td>4</td><td>330</td><td>20</td><td>HR-120</td><td>16</td><td>HR-160</td><td>30</td><td>690</td><td>4</td><td>602 CA</td><td>4</td><td>600</td><td>12</td></tr><tr><td>3</td><td>601</td><td>15</td><td>214</td><td>12</td><td>690</td><td>25</td><td>602 CA</td><td>3</td><td>330</td><td>3</td><td>602 CA</td><td>9</td></tr><tr><td>2</td><td>800H</td><td>10</td><td>602 CA</td><td>8</td><td>600</td><td>20</td><td>330</td><td>2</td><td>690</td><td>2</td><td>330</td><td>6</td></tr><tr><td>1</td><td>602 CA</td><td>5</td><td>330</td><td>4</td><td>800H</td><td>15</td><td>HR-120</td><td>1</td><td>HR-120</td><td>1</td><td>690</td><td>3</td></tr></tbody></table>
<table><caption>Table 14: Benchmark alloys' score concerning complementary data</caption><thead><tr><th rowspan="2">Rank points</th><th rowspan="2">Characteristics</th><th colspan="2">HIP compatibility</th><th colspan="2">Alloy cost (plate case)</th></tr><tr><th colspan="2">6</th><th colspan="2">5</th></tr><tr><th></th><th>Property weighting</th><th>Alloy</th><th>Score</th><th>Alloy</th><th>Score</th></tr></thead><tbody><tr><td>12</td><td rowspan="7">Alloys classification</td><td></td><td></td><td>330</td><td>60</td></tr><tr><td>11</td><td></td><td></td><td>800H</td><td>55</td></tr><tr><td>10</td><td></td><td></td><td>600</td><td>50</td></tr><tr><td>9</td><td></td><td></td><td>601</td><td>45</td></tr><tr><td>8</td><td></td><td></td><td>602 CA</td><td>40</td></tr><tr><td>7</td><td></td><td></td><td>690</td><td>35</td></tr><tr><td>6</td><td></td><td></td><td>HR-120</td><td>30</td></tr><tr><td>5</td><td></td><td></td><td>X</td><td>25</td></tr><tr><td>4</td><td></td><td>600</td><td>24</td><td>617</td><td>20</td></tr><tr><td>3</td><td></td><td>230</td><td>18</td><td>230</td><td>15</td></tr><tr><td>2</td><td></td><td>X</td><td>12</td><td>214</td><td>10</td></tr><tr><td>1</td><td></td><td>617</td><td>6</td><td>HR-160</td><td>5</td></tr></tbody></table>
Annex 3: Material certificates of alloys 600 and 230 used for mechanical characterization.

Alloy 600,10mm Plate

VDM Metals GmbH
sur commande de VDM Metals International GmbH

N° JACQUET :
0 9 5 7 8 2

VDM Metals

Certificat de reception 155496/0

DIN EN 10204/01.05 3.1

Notre N° de com. N° de livr. Votre N° de com.
506008 865286 78623

Page 1 de 2
imprimé le: 20. MAR 2017

JACQUET INTERNATIONAL

7 rue Michel Jacquet
F -69800 Saint-Priest

Nuance

VDM® Alloy 600

NICROFER 7216

2.4816

EN ISO 9001, AS 9100

LRQA Approval

KLN 4000941/B

ASME QSC-671, Date d'expiration

16 Mars, 2018

Produit

tôé, lamine à chaud, malléable recuite, décalamé, découpé

Spécification

Nuance

JACQUET Spec. FQ25 G rev. 14 07-juil-16

VDTÜVBL. 305/03.2015

ASTM B 168 - 11 (Reapproved 2016)

ASME Code Section II, Part B, ASME SB-168:2015

BS 3072: 1989

DIN EN 10095 - 05/1999

DIN 17742 09/2002

DIN 17750 09/2002

NiCr15Fe

UNS N06600

UNS N06600

NA 14

2.4816

NiCr 15Fe

<table><thead><tr><th>Pos</th><th>Nombre</th><th>Poids kg</th><th>Dimension [mm]</th><th>Coulée</th><th>Lot</th></tr></thead><tbody><tr><td>9</td><td>1</td><td>1042</td><td>10,000x</td><td>2000,0x</td><td>6000,0</td></tr><tr><td>11</td><td>1</td><td>1244</td><td>12,000x</td><td>2000,0x</td><td>6000,0</td></tr></tbody></table><table><thead><tr><th colspan="2">Dimension [mm]</th><th colspan="2">Coulée</th><th colspan="2">Lot</th></tr><tr><th>mm</th><th>mm</th><th>mm</th><th>mm</th><th>mm</th><th>mm</th></tr></thead><tbody><tr><td>2000,0</td><td>6000,0</td><td>120277</td><td>104624382</td><td></td><td></td></tr><tr><td>2000,0x</td><td>6000,0</td><td>120277</td><td>104624384</td><td></td><td></td></tr></tbody></table>

Comp. chimique (% poids)

LE=Analyse par combustion

OE=Analyse par emission optique

RF=Spectrométrie de fluorescence X

VDTÜVBL. 305/03.2015; ASTM B 168 - 11 (Reapproved 2016); ASME Code Section II, Part B, ASME SB-168:2015; BS 3072: 1989; DIN EN 10095 - 05/1999; DIN 17742 09/2002

<table><thead><tr><th>Coulée</th><th>Elaboration</th><th>C</th><th>S</th><th>Cr</th><th>Ni</th><th>Mn</th><th>Si</th><th>Ti</th><th>Cu</th><th>Fe</th><th>P</th><th>Al</th></tr></thead><tbody><tr><td>120277</td><td>FE/DV</td><td>0,065</td><td>&lt;0,002</td><td>16,17</td><td>R73,57</td><td>0,20</td><td>0,28</td><td>0,20</td><td>0,02</td><td>9,15</td><td>0,005</td><td>0,18</td></tr><tr><td></td><td>Meth</td><td>LE</td><td>LE</td><td>RF</td><td></td><td>RF</td><td>RF</td><td>RF</td><td>RF</td><td>RF</td><td>RF</td><td>RF</td></tr></tbody></table>

<table><thead><tr><th>Coulée</th><th>Elaboration</th><th>Co</th><th>B</th></tr></thead><tbody><tr><td>120277</td><td>FE/DV</td><td>0,02</td><td>0,002</td></tr><tr><td></td><td>Meth</td><td>RF</td><td>OE</td></tr></tbody></table>

Condition de l' éprouvette
malléable recuite

<table><thead><tr><th rowspan="2">Lot</th><th rowspan="2">N° d' éprouvette</th><th colspan="5">Essai de traction</th><th colspan="5">Essai de dureté</th></tr><tr><th>Temp [°C]</th><th>Rp0.2 [MPa]</th><th>Rp1.0 [MPa]</th><th>Rm [MPa]</th><th>Allong. A [%]</th><th>A [%]</th><th>Z [%]</th><th>HBW 2.5/187.5</th><th></th></tr></thead><tbody><tr><td>104624382</td><td>1595-K1</td><td>2</td><td>450</td><td>262</td><td></td><td>668</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>104624382</td><td>1595-K1</td><td>1</td><td>RT</td><td>331</td><td>380</td><td>716</td><td>A</td><td>45,4</td><td>80</td><td>45,4</td><td></td></tr><tr><td>104624382</td><td>1595-K1</td><td>3</td><td>RT</td><td>332</td><td></td><td>716</td><td>50</td><td>44,6</td><td></td><td></td><td></td></tr><tr><td>104624384</td><td>1688-K1</td><td>2</td><td>450</td><td>254</td><td></td><td>666</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>104624384</td><td>1688-K1</td><td>1</td><td>RT</td><td>314</td><td>361</td><td>710</td><td>A</td><td>41,6</td><td>80</td><td>42,3</td><td></td></tr><tr><td>104624384</td><td>1688-K1</td><td>3</td><td>RT</td><td>318</td><td></td><td>710</td><td>50</td><td>48,1</td><td></td><td></td><td></td></tr></tbody></table>

Nous confirmons que le matériel est en accord avec les spécifications indiquées ci-dessus

Tel. +49 2392 552092

Fax

Email thorsten.mueller@vdm-metals.com

Thorsten Müller, représentant de l'Inspection autorisé

Autorisation pour expédition: 20.03.2017

Siret expert usine

E

Q

* 155496-0-F *

Ce Certificat de conformité authentique ne doit pas être reproduit, sauf dans son intégralité, sans autorisation écrite de VDM Metals. L'enregistrement de fausses données, de déclarations fictives ou mensongères dans le certificat est susceptible de poursuivre pénale selon le droit allié.

VDM Metals GmbH

Division Tites

Fluxenberger Straße 2, D-68291 Wertheim

Postfach 1620, D-18779 Wertheim

Téléphone: 02392 55-6. Téléfax: 02392 55-2217

Internet: www.ued-metals.com

Président du Concil de Sûrence: Dr. Thomas Ludwig

President: Dr. Nicholas Müller

Andréa Biaure, Dr.-Ing. François-Joël Wathiers

Registre du commerce: Berthele 1-889 5327

Siège social: Wertheim
VDM Metals GmbH
sur commande de VDM Metals International GmbH

<table><tr><td>N° JACQUET :</td></tr><tr><td>0 9 5 7 8 2</td></tr></table>

VDM Metals

Certificat de reception 155496/0

DIN EN 10204/01.05 3.1

Notre N° de com. N° de livr. Votre N° de com.
506006 865286 78623

Page 2 de 2
imprimé le: 20. MAR 2017

<table><thead><tr><th colspan="2">Condition de l' éprouvette<br/>malléable recuite</th><th>Grosseur de grain<br/>1 ASTM E112 - 13</th></tr><tr><th>Lot</th><th>N° d' éprouvette</th><th></th></tr></thead><tbody><tr><td>104624382</td><td>1595-K1</td><td rowspan="2">1 No 8.5</td></tr><tr><td>104624382</td><td>1595-K1</td></tr><tr><td>104624384</td><td>1688-K1</td><td rowspan="2">1 No 8</td></tr><tr><td>104624384</td><td>1688-K1</td></tr><tr><td>104624384</td><td>1688-K1</td><td></td></tr></tbody></table>

<table><thead><tr><th>Traitement thermique</th><th>Lot</th></tr></thead><tbody><tr><td>1035°C/19min./eau</td><td>104624384</td></tr><tr><td>1037°C/22min./eau</td><td>104624382</td></tr></tbody></table>

Analyse spectrographique par piézo a étal/PMI check réalisée: conforme

Contrôle dimensionnel et de surface ont été réalisés: conforme

Aucune contamination mercurique; ni une source de radium, ni une source irradiante ou une source de rayons alpha n'a été utilisée lors de la production.

Sans exécution de réparation par scudure.

Le VDTUEV-feuille confirmation ci-dessus ne comprend que les examens confirmés dans le certificat.

VDM Metals GmbH

Division Tites

Pionniergerne Strasse 2, D-58781 Werdel

Postfach 1820, D-58770 Werdel

Telephone: 02392 55-1, Téléfax: 02392 55-2217

Internet: www.vdm-metals.com

Président du Conseil de Surveillance: Dr. Thomas Enderig

Président: Dr. Nicos Müller

Andrea Baar, Dr.-Ing. Frank-Josef Mahlers

Regisseur du consommateur: Torsten HRB 5327

Siège social Werdel:
Alloy 230, 9,53mm Plate

<figure><img src="image_98.png" /></figure>

<figure><img src="image_99.png" /></figure>
Alloy 230, 9,53mm Plate

<figure><img src="image_100.png" /></figure>

Certified By • Certifi Par • Bescheinigt Durch: Roberta Collins
Certification Technician

2/15/2012

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Alloy 230, 6mm Plate

<figure><img src="image_102.png" /></figure>

Certified By • Certifi Par • Bescheinigt Durch: Jessica Holt
Certification Technician

6/7/2018

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Annex 4: Mechanical sample drawings

Tensile samples

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Charpy V-notch impact samples

<figure><img src="image_105.png" /></figure>
Creep samples

<figure><img src="image_106.png" /></figure>

Fatigue samples

<figure><img src="image_107.png" /></figure>
Annex 5: Tensile test results

Room temperature tensile tests

<table><thead><tr><th>Alloy</th><th>Mock-up type</th><th>Sample</th><th>0.2% Yield strength (MPa)</th><th>Ultimate tensile strength (MPa)</th><th>Elongation (%)</th><th>Reduction in area (%)</th><th>Remarks</th></tr></thead><tbody><tr><td rowspan="12">600</td><td rowspan="4">Base material</td><td>HI-1</td><td>267</td><td>692</td><td>29.7</td><td>57.7</td><td>Rupture on gage length limit</td></tr><tr><td>HI-2</td><td>267</td><td>696</td><td>39.3</td><td>69.7</td><td>No remark</td></tr><tr><td>HI-3</td><td>264</td><td>695</td><td>39.7</td><td>71.1</td><td>No remark</td></tr><tr><td>HI-4</td><td>260</td><td>695</td><td>40.5</td><td>72.0</td><td>No remark</td></tr><tr><td rowspan="4">Two interfaces</td><td>O-1</td><td>298</td><td>676</td><td>33.8</td><td>58.0</td><td>No remark</td></tr><tr><td>O-2</td><td>313</td><td>692</td><td>34.1</td><td>55.5</td><td>No remark</td></tr><tr><td>O-3</td><td>311</td><td>696</td><td>38.1</td><td>63.6</td><td>No remark</td></tr><tr><td>O-4</td><td>313</td><td>698</td><td>37.2</td><td>66.3</td><td>No remark</td></tr><tr><td rowspan="4">One interface</td><td>A-1</td><td>290</td><td>692</td><td>39.6</td><td>65.1</td><td>No remark</td></tr><tr><td>A-2</td><td>271</td><td>696</td><td>39.5</td><td>64.8</td><td>No remark</td></tr><tr><td>A-3</td><td>265</td><td>696</td><td>35.6</td><td>61.9</td><td>No remark</td></tr><tr><td>A-4</td><td>270</td><td>697</td><td>39.5</td><td>67.9</td><td>No remark</td></tr><tr><td rowspan="12">230</td><td rowspan="4">Base material</td><td>HI-1</td><td>426</td><td>914</td><td>34.4</td><td>34.7</td><td>No remark</td></tr><tr><td>HI-2</td><td>425</td><td>911</td><td>36.7</td><td>36.2</td><td>No remark</td></tr><tr><td>HI-3</td><td>429</td><td>909</td><td>36.5</td><td>35.7</td><td>No remark</td></tr><tr><td>HI-4</td><td>455</td><td>915</td><td>36.2</td><td>40.9</td><td>No remark</td></tr><tr><td rowspan="4">Two interfaces</td><td>O-1</td><td>378</td><td>776</td><td>18.1</td><td>27.6</td><td>No remark</td></tr><tr><td>O-2</td><td>368</td><td>769</td><td>16.5</td><td>21.4</td><td>No remark</td></tr><tr><td>O-3</td><td>384</td><td>774</td><td>17.5</td><td>22.1</td><td>No remark</td></tr><tr><td>O-4</td><td>380</td><td>778</td><td>17.5</td><td>20.5</td><td>No remark</td></tr><tr><td rowspan="4">One interface</td><td>A-1</td><td>430</td><td>836</td><td>19.7</td><td>23.0</td><td>No remark</td></tr><tr><td>A-2</td><td>446</td><td>833</td><td>19.3</td><td>21.1</td><td>No remark</td></tr><tr><td>A-3</td><td>430</td><td>833</td><td>17.3</td><td>20.5</td><td>No remark</td></tr><tr><td>A-4</td><td>439</td><td>845</td><td>20.9</td><td>21.4</td><td>No remark</td></tr></tbody></table>
870°C tensile tests

<table><thead><tr><th>Alloy</th><th>Mock-up type</th><th>Sample</th><th>0.2% Yield strength (MPa)</th><th>Ultimate tensile strength (MPa)</th><th>Elongation (%)</th><th>Reduction in area (%)</th><th>Remarks</th></tr></thead><tbody><tr><td rowspan="12">600</td><td rowspan="4">Base material</td><td>HI-5</td><td>101</td><td>115</td><td>64.2</td><td>92</td><td>No remark</td></tr><tr><td>HI-6</td><td>94</td><td>109</td><td>60.2</td><td>91</td><td>No remark</td></tr><tr><td>HI-7</td><td>94</td><td>108</td><td>62.5</td><td>91</td><td>No remark</td></tr><tr><td>HI-8</td><td>97</td><td>110</td><td>63.1</td><td>92</td><td>No remark</td></tr><tr><td rowspan="4">Two interfaces</td><td>O-5</td><td>90</td><td>101</td><td>3.3</td><td>5.4</td><td>No remark</td></tr><tr><td>O-6</td><td>92</td><td>101</td><td>2.3</td><td>5.9</td><td>No remark</td></tr><tr><td>O-7</td><td>97</td><td>103</td><td>1.7</td><td>4.5</td><td>No remark</td></tr><tr><td>O-8</td><td>90</td><td>103</td><td>2.6</td><td>1.9</td><td>No remark</td></tr><tr><td rowspan="12">230</td><td rowspan="4">Base material</td><td>HI-5</td><td>237</td><td>260</td><td>68.3</td><td>72</td><td>No remark</td></tr><tr><td>HI-6</td><td>247</td><td>259</td><td>64.1</td><td>71</td><td>No remark</td></tr><tr><td>HI-7</td><td>237</td><td>256</td><td>59.8</td><td>67</td><td>No remark</td></tr><tr><td>HI-8</td><td>232</td><td>259</td><td>59.9</td><td>72</td><td>No remark</td></tr><tr><td rowspan="4">Two interfaces</td><td>O-5</td><td>/</td><td>200</td><td>0.87</td><td>2.1</td><td>No remark</td></tr><tr><td>O-6</td><td>/</td><td>189</td><td>0.78</td><td>3.6</td><td>No remark</td></tr><tr><td>O-7</td><td>/</td><td>193</td><td>0.78</td><td>1.6</td><td>No remark</td></tr><tr><td>O-8</td><td>/</td><td>137</td><td>0.43</td><td>1.4</td><td>No remark</td></tr></tbody></table>
Annex 6: Charpy V-notch impact test results

<table><thead><tr><th>Alloy</th><th>Mock-up type</th><th>Sample</th><th>Energy to<br>rupture (J)</th><th>Rupture</th><th>Remarks</th></tr></thead><tbody><tr><td rowspan="10">600</td><td rowspan="7">Base material</td><td>I-1</td><td>272.5</td><td>Yes</td><td>No remark</td></tr><tr><td>I-2</td><td>277.0</td><td>Yes</td><td>No remark</td></tr><tr><td>I-3</td><td>264.4</td><td>Yes</td><td>No remark</td></tr><tr><td>I-4</td><td>261.6</td><td>Yes</td><td>No remark</td></tr><tr><td>I-5</td><td>275.6</td><td>Yes</td><td>No remark</td></tr><tr><td>I-6</td><td>251.3</td><td>Yes</td><td>No remark</td></tr><tr><td>I-7</td><td>280.4</td><td>Yes</td><td>No remark</td></tr><tr><td rowspan="15">Two interfaces</td><td colspan="5">Interface 1</td></tr><tr><td>B-1</td><td>110.9</td><td>Yes</td><td>No remark</td></tr><tr><td>B-3</td><td>111.7</td><td>Yes</td><td>No remark</td></tr><tr><td>B-5</td><td>102</td><td>Yes</td><td>No remark</td></tr><tr><td colspan="5">Interface 2</td></tr><tr><td>B-2</td><td>109.1</td><td>Yes</td><td>No remark</td></tr><tr><td>B-4</td><td>109.9</td><td>Yes</td><td>No remark</td></tr><tr><td>B-6</td><td>109</td><td>Yes</td><td>No remark</td></tr><tr><td rowspan="7">Base material</td><td>I-1</td><td>66.6</td><td>Yes</td><td>No remark</td></tr><tr><td>I-2</td><td>66.5</td><td>Yes</td><td>No remark</td></tr><tr><td>I-3</td><td>65.0</td><td>Yes</td><td>No remark</td></tr><tr><td>I-4</td><td>162.2</td><td>No</td><td>Not taken into account due<br>abnormal shape after test</td></tr><tr><td>I-5</td><td>64.9</td><td>Yes</td><td>No remark</td></tr><tr><td>I-6</td><td>64.4</td><td>Yes</td><td>No remark</td></tr><tr><td>I-7</td><td>62.7</td><td>Yes</td><td>No remark</td></tr><tr><td rowspan="10">230</td><td rowspan="7">Two interfaces</td><td colspan="5">Interface 1</td></tr><tr><td>B-1</td><td>25.6</td><td>Yes</td><td>No remark</td></tr><tr><td>B-3</td><td>14.9</td><td>Yes</td><td>Not taken into account due<br>sample out of tolerance</td></tr><tr><td>B-5</td><td>24.9</td><td>Yes</td><td>No remark</td></tr><tr><td colspan="5">Interface 2</td></tr><tr><td>B-2</td><td>26</td><td>Yes</td><td>No remark</td></tr><tr><td>B-4</td><td>25.5</td><td>Yes</td><td>No remark</td></tr><tr><td>B-6</td><td>23.9</td><td>Yes</td><td>No remark</td></tr></tbody></table>
Annex 7: Creep test results done at 870°C

<table><thead><tr><th>Alloy</th><th>Mock-up type</th><th>Stress (MPa)</th><th>Sample</th><th>Time to rupture or stop (h)</th><th>Secondary creep strain rate (‰.10<sup>-6</sup>s<sup>-1</sup>)</th><th>Remarks</th></tr></thead><tbody><tr><td rowspan="9">600</td><td rowspan="3">Base material</td><td>22</td><td>J-2</td><td>585</td><td>7.19</td><td></td></tr><tr><td>20</td><td>J-3</td><td>756</td><td>4.92</td><td></td></tr><tr><td>18</td><td>J-4</td><td>1369</td><td>2.41</td><td></td></tr><tr><td rowspan="3">Two interfaces</td><td>22</td><td>C-2</td><td>32</td><td>10.9</td><td></td></tr><tr><td>20</td><td>C-3</td><td>20.4</td><td>6.39</td><td></td></tr><tr><td>18</td><td>C-4</td><td>50.6</td><td>4.75</td><td></td></tr><tr><td rowspan="9">230</td><td rowspan="3">Base material</td><td>70</td><td>C-1</td><td>669</td><td>6.36</td><td>Stop before breaking</td></tr><tr><td>60</td><td>C-2</td><td>668</td><td>0.95</td><td>Stop before breaking</td></tr><tr><td>50</td><td>C-3</td><td>669</td><td>0.19</td><td>Stop before breaking</td></tr><tr><td rowspan="3">Two interfaces</td><td>70</td><td>C-1</td><td></td><td></td><td>Broken during loading phase</td></tr><tr><td>60</td><td>C-2</td><td></td><td></td><td>Broken during loading phase</td></tr><tr><td>50</td><td>C-3</td><td>1.45</td><td></td><td></td></tr></tbody></table>
Annex 8: Fatigue test results

<table><thead><tr><th>Alloy</th><th>Mock-up type</th><th>Temperature (°C)</th><th>Strain range (±%)</th><th>Sample</th><th>Cycle to failure</th><th>Remarks</th></tr></thead><tbody><tr><td rowspan="12">600</td><td rowspan="3">Base material</td><td rowspan="3">20</td><td>0.4</td><td>N-2</td><td>13326</td><td>Broken</td></tr><tr><td>0.3</td><td>M-2</td><td>44229</td><td>Broken</td></tr><tr><td>0.2</td><td>L-3</td><td>100000</td><td>Test stopped, non-broken</td></tr><tr><td rowspan="3">Two interfaces</td><td rowspan="3">870</td><td>0.2</td><td>L-4</td><td>5478</td><td>Broken</td></tr><tr><td>0.15</td><td>M-4</td><td>15888</td><td>Broken</td></tr><tr><td>0.1</td><td>N-3</td><td>100000</td><td>Test stopped, non-broken</td></tr><tr><td rowspan="6">20</td><td rowspan="3">Two interfaces</td><td rowspan="3">870</td><td>0.4</td><td>G-1</td><td>6785</td><td>Broken</td></tr><tr><td>0.3</td><td>F-1</td><td>14259</td><td>Broken</td></tr><tr><td>0.2</td><td>E-1</td><td>54379</td><td>Broken</td></tr><tr><td rowspan="3">Two interfaces</td><td rowspan="3">870</td><td>0.2</td><td>E-2</td><td></td><td>Not tested</td></tr><tr><td>0.15</td><td>F-4</td><td></td><td>Not tested</td></tr><tr><td>0.1</td><td>G-4</td><td></td><td>Not tested</td></tr><tr><td rowspan="12">230</td><td rowspan="3">Base material</td><td rowspan="3">20</td><td>0.5</td><td>N-1</td><td>7670</td><td>Broken</td></tr><tr><td>0.4</td><td>M-3</td><td>22782</td><td>Broken</td></tr><tr><td>0.3</td><td>L-3</td><td>100000</td><td>Test stopped, non-broken</td></tr><tr><td rowspan="3">Two interfaces</td><td rowspan="3">870</td><td>0.25</td><td>L-4</td><td>5119</td><td>Broken</td></tr><tr><td>0.2</td><td>M-4</td><td>20738</td><td>Broken</td></tr><tr><td>0.15</td><td>N-3</td><td>100000</td><td>Test stopped, non-broken</td></tr><tr><td rowspan="3">Two interfaces</td><td rowspan="3">870</td><td>0.5</td><td>G-1</td><td>874</td><td>Broken</td></tr><tr><td>0.4</td><td>F-1</td><td>727</td><td>Broken</td></tr><tr><td>0.3</td><td>E-1</td><td>41594</td><td>Broken</td></tr><tr><td rowspan="3">Two interfaces</td><td rowspan="3">870</td><td>0.25</td><td>E-4</td><td></td><td>Not tested</td></tr><tr><td>0.2</td><td>F-4</td><td></td><td>Not tested</td></tr><tr><td>0.15</td><td>G-4</td><td></td><td>Not tested</td></tr></tbody></table>