bluuebunny/crossref_metadata_2025_split huggingface dataset:
Coal Ash Corrosion Resistant Materials Testing Program: Evaluation of the Second Section Removed in August 2003
Authors: McDonald Dennis K. , Robitz Edward S. 
Published: July 2024

Abstract
The “Coal Ash Corrosion Resistant Materials Testing Program” by The Babcock & Wilcox Company (B&W), the U.S. Department of Energy (DOE), and the Ohio Coal Development Office (OCDO) at Reliant Energy's Niles plant provides full-scale in-situ testing of advanced boiler superheater materials to address fireside corrosion, a key issue for improving efficiency in new coal-fired plants and service life in existing ones. In 1998, B&W developed a system with three identical sections containing multiple segments of twelve different materials from contributors like Oak Ridge National Laboratory (ORNL), cooled by reheat steam and installed in 1999 above the furnace entrance in the Niles Plant 110 MWe Unit #1 firing high-sulfur Ohio coal to test materials at advanced supercritical steam temperatures (1100°F+) in corrosive conditions. The first section was evaluated after 29 months in 2001, the second in 2003, and the final section is expected for removal in 2005. This paper outlines the program, test system, and materials, and it presents the evaluation results for the first two sections.
Corrosion Behavior of an HVOF-Sprayed Fe3Al Coating in a High-Temperature Oxidizing/Sulfidizing Environment
Authors: Covino B. S. , Bullard S. J. , Cramer S. D. , Holcomb G. R. , Ziomek-Moroz M. , Shrestha S. , Harvey D. 
Published: July 2024

Abstract
An iron aluminide (Fe3Al) intermetallic coating was deposited onto F22 (2.25Cr-1Mo) steel substrate using a JP-5000 high velocity oxy-fuel (HVOF) thermal spray system. The as-sprayed coating was characterized by electron microscopy, X-ray diffraction, oxidation, and adhesion. Fe3Al coated steel specimens were exposed to a mixed oxidizing/sulfidizing environment of N2-10%CO-5%CO2-2%H2O-0.12%H2S (by volume) at 500, 600, 700, and 800°C for approximately seven days. All specimens gained mass after exposure, inversely proportional to temperature increases. Representative cross-sectioned specimens from each temperature underwent scanning electron microscopy (SEM) and X-ray mapping examination. Results are presented in terms of corrosion weight gain and product formation. The research evaluated the effectiveness of an HVOF-sprayed Fe3Al coating in protecting a steel substrate exposed to a fossil energy environment.
Steam Oxidation Property of Fine-Grain Steels
Authors: Matsuo H. , Nishiyama Y. , Yamadera Y. 
Published: July 2024

Abstract
This paper describes the steam oxidation behavior of two 18Cr-8Ni austenitic fine-grained stainless steels, TP347HFG and SUPER304H, which have been developed for ultra-supercritical (USC) boilers. A field exposure test was conducted by installing these tubes, along with comparative materials, in the tertiary superheater of a utility power boiler. After periodic service, the fine-grained tubes were removed to examine their steam oxidation behavior. Examination of the steam oxidation scale on the inner surface of the tubes indicated an extremely low scale growth rate for the fine-grained steels, even after 10 years of service. The oxidation structure is discussed and compared with conventional materials, TP321H and TP347H. Accelerated steam oxidation tests were conducted using an oxidation test with saturated dissolved oxygen concentration. The combination of fine-grained steel and a shot-peening layer exhibits high steam oxidation resistance at 700°C or higher temperatures.
Effect of Argon Gas Pre-Oxidation Treatment on the Oxidation Behavior of NIMS High-Strength Steels
Authors: Kutsumi H. , Haruyama H. , Abe F. 
Published: July 2024

Abstract
For high-strength steels developed at the National Institute for Materials Science (NIMS) in Japan, a dispersion of nano-sized MX nitride particles along boundaries and in the matrix is achieved by reducing carbon concentration below 0.02%. This structure results in excellent creep strength at 923K, approximately two orders of magnitude longer rupture time than P92. Additionally, adding a large amount of boron exceeding 0.01% combined with minimized nitrogen effectively improves creep rupture strength by stabilizing the martensitic microstructure during creep. Efforts have been made to enhance the steam oxidation resistance of these 9Cr steels strengthened by boron and fine MX nitrides. A combination of 0.7% Si, 40-60 ppm S, and pre-oxidation treatment was applied. Steam oxidation tests were conducted at 923K for up to 4000h. Pre-oxidation treatment in argon gas at 973K for 50h significantly improved oxidation resistance in steam at 923K by forming a protective Cr-rich oxide layer. The pre-oxidized steels exhibited much lower mass gain in steam at 923K than Mod.9Cr-1Mo steel at 873K, and lower than T91 at 873K after 1000h. After 4000h, their mass gain was about zero, much lower than P91 at 873K and 923K. SEM/EDS analysis and low mass gain suggest a protective Cr-rich oxide scale formed on the pre-oxidized steel surface, exhibiting excellent oxidation resistance in steam at 923K.
Oxide Scaling and Oxidation-Assisted Microstructural Degradation in Weldments Steam Generator Steels
Authors: Raman R.K. Singh 
Published: July 2024

Abstract
‘Chromium-Molybdenum’ ferritic steels are the most popular materials for construction of steam generators. Microstructure of ‘Cr-Mo’ steels is highly susceptible to changes due to heat- treatments. This susceptibility is often exploited for improving creep strength of these alloys, via suitable heat treatments, that are employed in order to incorporate changes in grain size and secondary precipitates. This paper presents a general overview of the role of microstructure in various aspects of gaseous oxidation, and the synergistic role of the alloy microstructure and oxidation in deterioration of mechanical properties. In the light of this overview, the paper also presents oxidation kinetics and oxidation-assisted microstructural degradation in the microstructurally different regions of weldments of a common variety of ‘Cr-Mo’ steel, viz., 2.25Cr-1Mo steel.
Materials and Design for Advanced High Temperature Steam Turbines
Authors: Fukuda Masafumi , Tsuda Yoichi , Yamashita Katsuya , Shinozaki Yukio , Takahashi Takeo 
Published: July 2024

Abstract
Natural gas has long been regarded as the primary energy source for advanced power systems because of its cleanliness and highly efficient nature. Nevertheless, coal is gaining attention again as a stable energy source for power generation. In this paper, high efficiency pulverized coal power plant technology, especially materials and the design for high temperature turbine systems, is discussed. The development of materials has contributed to the high efficiency plant development, so far. The development of 12% Cr steel was key in building the state-of-the-art 600-deg C class steam turbine system. It is believed that a 700-deg C class steam turbine system will be realized with Ni-based super alloys and austenitic steels. In the near future, the system with a 700-deg C reheat temperature and 630-deg C main steam temperature is promising for the pulverized coal power plant because of the need for only moderate development work, low capital expenditure, and its high efficiency.
Superalloy Forgings for Advanced High Temperature Power Plants
Authors: Schönfeld K.H. , Blaes N. , Bokelmann D. 
Published: July 2024

Abstract
Improving power plant efficiency through supercritical steam pressures and very high steam temperatures up to 700°C and beyond is an effective approach to reducing fuel consumption and CO2 emissions. However, these extreme steam temperatures necessitate the use of nickel-base alloys in the high-pressure/intermediate-pressure turbine sections requiring very large component sections that cannot be met by steels. Saarschmiede, involved in manufacturing large components for the power generation industry and research programs on advanced 9-12% chromium steels, has extensive experience producing nickel and cobalt-base alloy forgings for applications like aircraft engines, aerospace, land-based gas turbines, and offshore. This paper reports on the manufacturing and testing of large-section forgings made from candidate nickel-base alloys like 617 and 625 for high-pressure/intermediate-pressure turbine components in power stations operating at 700°C and higher steam temperatures.
High Temperature Steel Forgings for Power Generation
Authors: Blaes N. , Donth B. , Schönfeld K.H. , Bokelmann D. 
Published: July 2024

Abstract
Steels with 9-12% chromium content are widely used in steam turbines operating above 550°C due to their improved creep properties. Saarschmiede has extensive experience manufacturing high chromium steels, such as the X12CrMoWVNbN10-11-1 steel designed through the European COST program for application up to 610°C (COST Rotor E). From this steel, Saarschmiede produces high-pressure rotor shafts and gas turbine discs. To meet ever-increasing steam temperatures, a modified steel type with elevated boron content was developed, and pilot rotors have been manufactured. For ingot manufacturing of high chromium steels, Saarschmiede utilizes the Electro-Slag-Remelting process, allowing ingots up to 165 tons. Optimized forging and heat treatment procedures ensure reproducible forging properties. All products undergo rigorous destructive and non-destructive testing.
Wrought Nl-Base Alloys for Rotor Shafts in Advanced USC Power Plants
Authors: Schubert F. , Penkalla H.J. , Rösler J. 
Published: July 2024

Abstract
Three Ni-base wrought alloys with different hardening mechanisms (INCONEL 706, Waspaloy and INCONEL 617) were investigated as candidates for steam turbine rotor applications at temperatures up to 700 °C in respect to their microstructure and microstructural stability. The Nb containing alloy Inconel 706 had a complex microstructure with γ', γ" and η phases which are stable in long term service up to 620 °C. At higher temperatures significant particle coarsening and phase transformation were observed. Waspaloy is hardened by γ' particles and after ageing at 700 °C and higher, it tended to a stable microstructure. Inconel 617 is a solid solution hardened material additionally hardened by homogeneously distributed fine M23C6 carbides. After long term ageing at temperatures of 650 °C to 750 °C the carbides tended to form carbide films along the grain boundaries and at 700 °C to 750 °C γ' precipitated as homogeneously distributed particles with low coarsening during long term service. In order to optimize the candidate alloys Inconel 706 and Waspaloy were modified to the new alloys DT 706 and DT 750. The aspects of modification and first experimental results are reported.
Development of Wrought Ni-Based Superalloy with Low Thermal Expansion for 700C Steam Turbines
Authors: Yamamoto Ryuichi , Kadoya Yoshikuni , Ueta Shigeki , Noda Toshiharu , Magoshi Ryotaro , Nishimoto Shin , Nakano Takashi 
Published: July 2024

Abstract
Advanced 700C class steam turbines require austenitic alloys instead of conventional ferritic heat-resistant steels which have poor creep strength and oxidation resistance above 650C. Austenitic alloys, however, possess a higher thermal expansion coefficient than ferritic 12Cr steels. Therefore, Ni-based superalloys were tailored to reduce their coefficients to the level of 12Cr steels. Regression analysis of commercial superalloys proves that Ti, Mo and Al decrease the coefficient quantitatively in this order, while Cr, used to secure oxidation resistance, increases it so significantly that Cr should be limited to 12wt%. The newly designed Ni-18Mo-12Cr-l.lTi-0.9Al alloy is strengthened by gamma-prime [Ni3(Al,Ti)] and also Laves [Ni2(Mo,Cr)] phase precipitates. It bears an RT/700C mean thermal expansion coefficient equivalent to that of 12Cr steels and far lower than that of low-alloyed heat resistant steels. Its creep rupture life at 700C and steam oxidation resistance are equivalent to those of a current turbine alloy, Refractaloy 26, and its tensile strength at RT to 700C surpasses that of Refractaloy 26. The new alloy was trial produced using the VIM-ESR melting process and one ton ingots were successfully forged into round bars for bolts without any defects. The bolts were tested in an actual steam turbine for one year. Dye penetrant tests detected no damage. The developed alloy will be suitable for 700C class USC power plants.
Perspectives on Improved Life Assessment Methods for New Plants
Authors: Berger Christina , Scholz Alfred 
Published: July 2024

Abstract
New martensitic steels (9-10 CrMoNi(W)VNbN) are being developed for ultrasupercritical power plants to achieve higher efficiency and reduced environmental impact. Improved life assessment methods are crucial for the safe and economical long-term operation of these high-temperature components. This includes gathering creep, creep-fatigue, and crack data to establish design curves, as well as advanced modeling to predict deformation and lifetime. Complex experiments under various loading conditions and multiaxial behavior are necessary for verification. Furthermore, understanding how creep processes affect pre-existing defects is essential for ensuring long-term component integrity.
Evaluation of the Failure in the Texas Genco W. A. Parish Unit #8 Cold Reheat Line
Authors: Alexander Chris , Frey, P.E. Joe , Shin Steve 
Published: July 2024

Abstract
Texas Genco requested Stress Engineering Services to assist in reviewing and assessing a failure that occurred in the cold reheat (CRH) steam line at the W.A. Parish Unit around 12:10 PM on July 15, 2003, resulting in a catastrophic failure scattering components within a 1,200-foot radius. Reliant Resources and Texas Genco conducted their own investigation involving metallographic examinations, fracture surface inspection, review of operating conditions at failure time, and studies related to the CRH line weld profile. Stress Engineering Services' efforts included computational fluid dynamics studies to address how attemperator droplet sizes might impact downstream piping system behavior, followed by mock-up testing and field monitoring using high-temperature strain gauges, accelerometers, and thermocouples. The field monitoring data, along with process data from Texas Genco, were used for finite element analyses calculating static stresses and transient stresses from attemperator cycling (thermal stresses) and line vibration (mechanical stresses). A consulting firm contracted by the Electric Power Research Institute (EPRI) performed a fracture mechanics evaluation of the line, though detailed results are not included. The work by Texas Genco, Stress Engineering Services, and EPRI points to the stress concentration factor associated with the internal weld profile near the failure as the primary cause, with the cyclic thermal shocks from frequent intermittent attemperator use being sufficient to initiate the crack.
Life Management of High Energy Piping Systems - An Integrated Maintenance and Operations Approach
Authors: Tilley R. 
Published: July 2024

Abstract
To obtain the maximum life for fossil power plant high energy piping systems requires a management process that goes beyond a maintenance response to discovered damage or problems. The catastrophic failure of a cold reheat piping system in 2003 and the ongoing damage reported for feedwater and steam piping systems in other power plants suggest a need for a comprehensive process of life management This paper proposes a process based upon the successful EPRI program for boiler tube failure reduction. Key to this process is a structure that fully confirms the damage or failure mechanism, that identifies the root cause for the mechanism, and that establishes short and long-term corrective actions for the damage. Finally, the process must be implemented through a cross-functional team of plant staff covering maintenance, operations, and engineering disciplines to assure the most complete and cost effective actions to prevent future damage.
Stability of Similar and Dissimilar Welded Joints, High-Temperature Creep Resistant Martensitic Steels Containing 9% Cr
Authors: Pasternak Jerzy , Kielbus Andrzej 
Published: July 2024

Abstract
This paper presents RAFAKO S.A. experience within the field of research and implementation of new group of creep-resistant steel grades with addition of tungsten, including the selection of filler metal, welding procedures and selected results of mechanical properties testing carried out during the implementation of welding process for elements of steam superheaters of the boilers with supercritical parameters. It summarizes the experience and results of research works carried out in RAFAKO, Silesian Technical University in Katowice and Welding Institute in Gliwice within the framework of COST 522 program concerning the influence of simulation of element temperature operating conditions on Chaгpy V notch toughness, HV10 hardness, microstructure of simulated HAZ's, assessment of steel weldability, strength properties. The welded joints structure stability and HAZ after stress relief annealing and after ageing - simulation of element operating conditions are presented in the form of graphs and prints of microstructures.
VM12 - A New 12%Cr Steel for Boiler Tubes, Headers and Steam Pipes in Ultra Supercritical Power Plants
Authors: Gabrel J. , Bendick W. , Vaillant J.C. , Vandenberghe B. , Lefebvre Bo. 
Published: July 2024

Abstract
A new 12%Cr steel, VM12, has been developed with the combined strength and oxidation resistance characteristics desired for high-temperature applications. The steel increases chromium content by around 0.2% to improve oxidation properties while alloying with other elements such as cobalt, tungsten, and boron to meet a range of requirements, including extending fatigue life. The steel is designed to have the same creep strength as T/P92 but with better oxidation resistance due to the higher chromium content. It has about a 0.2% increase in mechanical properties compared to T/P92 steel. Results are presented for tubes and pipes cast with a variety of surface conditions. In addition, detailed results are provided on the effects of alloying elements on creep and oxidation resistance.
Z-Phase in 9-12%Cr Steels
Authors: Danielsen H. , Hald J. 
Published: July 2024

Abstract
The complex nitride Z-phase, Cr(V,Nb)N, has recently been identified as a major cause for premature breakdown in creep strength of a number of new 9-12%Cr martensitic steels, especially the high Cr variants. A thermodynamic model of the Z-phase has been created based on the Thermo-Calc software. The model predicts the Z-phase to be stable in all of the new 9- 12%Cr martensitic steels, and this has generally been confirmed by experimental observations. Z-phase precipitation seems then to be a kinetic problem, and driving force calculations, using Thermo-Calc with the developed model, have been used to predict steel compositions, which could delay Z-phase precipitation. The model also predicted the existence of a new niobium free Z-phase variant, which has since been discovered in a niobium free 12CrMoV steel.
Long Term Creep Behavior and Microstructural Evolution of ASTM Grade 91 Steel
Authors: Caminada S. , Cumino G. , Cipolla L. , Di Gianfrancesco A. 
Published: July 2024

Abstract
TenarisDalmine, in collaboration with CSM, developed and characterized ASTM Grade 91 steel tubes and pipes for high-temperature boilers in ultrasupercritical power plants. This paper details the mechanical properties of both untreated and long-term exposed tubes. Extensive creep testing allowed extrapolation of stress values for rupture in 100,000 hours (93 MPa at 600°C) and 1% elongation in 250,000 hours (83 MPa at 600°C), satisfying ECCC and TÜV requirements. Additionally, STEM analysis investigated microstructure and precipitate evolution after long-term exposure, revealing changes in precipitate chemistry, size, and distribution.
Degradation Processes in Creep of 9-12%Cr Ferritic Steels
Authors: Sklenicka V. , Kucharova K. , Kloc L. , Svoboda M. , Kudrman J. 
Published: July 2024

Abstract
Creep behavior and degradation of creep properties of advanced 9-12%Cr ferritic steels are phenomena of major practical relevance, often limiting the lives of power plant components and structures designed to operate for long periods under stress at elevated temperatures. Because life expectancy is, in reality, based on the ability of the material to retain its high-temperature creep strength for a period of at least twice the projected design life, methods of creep property assessment based on physical changes in the material that are likely to occur during service exposure rather than simple parametric extrapolation of the short-term data are necessary. This work attempts to highlight the problem areas just in this respect. The proposed approaches are illustrated by recent experimental results on advanced high creep strength 9-12%Cr ferritic- martensitic steels (P91 and P92).
Long-Term Creep Deformation Characteristics of Advanced Ferritic Steels for USC Power Plants
Authors: Igarashi M. , Yoshizawa M. 
Published: July 2024

Abstract
Creep deformation behavior of the T122 type steels with different matrix phases such as α’ (martensite) and α’+δ (martensite and delta-ferrite) at different stress levels has been studied comparing with those of the model steels with the initial microstructures consisting of the various combination of matrices such as ferrite (α), martensite (α’) and austenite (γ), and precipitates such as MX and M23C6. The heterogeneous creep deformation is found to be pronounced at lower stress level in the steel with a dual phase matrix of α’+δ, resulting in a complex sigmoidal nature in the creep rupture life. The creep deformation process of the steel with the dual phase matrix is similar to that of the model steel with the α phase matrix which exhibits a typical heterogeneous creep deformation and the early transition to the acceleration creep at a very small creep strain. Such a heterogeneous creep deformation is much pronounced along the interfaces between the soft δ ferrite and the hard martensite (α’) phases, and has a viscous nature in creep deformation which was first identified in P91 steel. It is concluded that the homogeneous microstructure is a key for achieving the long-term creep strength in the advanced ferritic steels at elevated temperatures over 600°C.
Effects of a New Thermo-mechanical Magnetic Heat Treatment Process on Creep Properties of High-Cr Ferritic Heat Resistant Steels
Authors: Okubo Hiroshi , Muneki Seiichi , Abe Fujio 
Published: July 2024

Abstract
Effect of thermomechanical and magnetic treatment on creep characteristics of advanced heat resistant ferritic steels for USC power plants has been investigated to explore fundamental guiding principles for improving creep rupture strength at elevated temperatures over 600°C. A model steel with a composition of Fe-0.08C-9Cr-3.3W-3Co-0.2V-0.05Nb-0.05N-0.005B-0.3Si-0.5Mn (in mass%) has been prepared by vacuum induction furnace. Creep tests at 650 °C and microstructural observations were performed on the thermomechanical and magnetic treated specimens after tempering. New thermomechanical treated samples without magnetic field showed some improvement in creep strength comparing with ordinarily normalized and tempered specimens. Further improvement was observed in the specimen that had been exposed to a magnetic field during transformation into the martensite. From the result of microstructural observation, it was found that the finely distributed precipitates such as MX and M23C6 caused this improvement. And it was suggested that the magnetic treatment at martensitic transformation increase the precipitation sites during tempering, resulting in increasing the amount and preventing the growth of the precipitates.