bluuebunny/crossref_metadata_2025 huggingface dataset:
A Review of Phosphate Ester Fire Resistance Mechanisms and Their Relevance to Fluid Testing
Authors: Marolewski TA , Weil ED
Published: March 2009

The fire resistance of phosphate esters is primarily a result of properties imparted by the phosphate nucleus. These properties make triaryl phosphate esters difficult to ignite and cause them to self-extinguish. Fluid fire resistance is a function of different chemical and/or physical characteristics depending on fire test configuration. Studies performed on phosphate esters for flame retardant and fire extinguishing applications provide useful analogies to fluid fire resistance. The soaked cube fire test predicts the oxidation exotherm temperature of a fluid on steam pipe lagging. The impact of fluid properties on the decomposition and ignition temperature is discussed. A simple extension of the fire point test was used to illustrate the fire resistance of various phosphate ester/polyol ester mixtures. The transition to a self-extinguishing mixture occurs over a narrow phosphate ester concentration range.
Flammability Screening and Fire Hazard of Industrial Fluids Using the Cone Calorimeter
Authors: Grand AF , Trevino JO
Published: March 2009

There are numerous qualitative test methods to evaluate the flammability characteristics of industrial fluids (e.g., hydraulic fluids). These methods generally are based on potentially hazardous scenarios such as ignition of fluid droplets by a hot manifold or fluid sprays by an open flame. However, there is a need for a reproducible, quantitative, bench-scale test for screening the potential flammability of industrial fluids in such a way that good engineering data are also obtained. Preliminary laboratory evaluations were conducted using the “cone calorimeter,” according to ASTM E1354, to assess the feasibility of this technique as a standard test method for industrial fluids. Specimens ranging in volume up to 28 mL in pans up to 100 mm diameter were evaluated, although most testing was conducted using 14 mL in 77 mm diameter pans. The specimens were exposed to external radiant heat fluxes of 25 to 50 kW/m2. Measured parameters included ignition time, heat release rate, mass loss, effective heat of combustion, and smoke evolution. The seven fluids evaluated had a broad range of flammability and smoke properties. Limited large scale comparison tests were conducted with 0.9 m diameter pool fires. The versatility, reliability and accuracy of the cone calorimeter applied to industrial fluids make it a viable candidate for consideration as a standard test method for screening and fire hazard analysis.
Structural Silicone Glazing: In-Service Reliability Evaluation
Authors: Schwartz TA , Zarghamee MS , Kan FW
Published: March 2009

A simple and cost effective procedure is presented for in-service evaluation of the reliability of structural silicone glazed curtain wall systems. The field test utilizes a point load apparatus to simulate the effect of a uniform wind load. The analytical bases of the field testing procedure include selecting an acceptable failure probability for the structural silicone system, performing finite element analysis to determine the stresses in the structural silicone, selecting the magnitude of the point load that produces the same stress in the structural silicone as a uniform design load, and performing statistical analysis of the data. We present a test procedure, test results and analysis procedure for a hypothetical case.
Effects of Accelerated Weathering on Architectural Laminated Glass in a Windstorm Environment
Authors: Behr RA , Minor JE , Kremer PA
Published: March 2009

An experimental study was conducted to assess the serviceability and ultimate limit state behavior of a fully glazed architectural laminated glass system under accelerated weathering conditions. Glazed specimens included heat-strengthened laminated glass with a low-emissivity, metallic solar coating on one glass surface next to the polyvinyl butyral interlayer. The laminated glass units were anchored to the aluminum curtain wall frame with a perimeter anchor bead of medium-modulus structural silicone sealant. Accelerated weathering was performed in a manner similar to the provisions of ASTM E773-88 and E774-92. All specimens (weathered and unweathered) were then subjected to a severe windstorm simulation test, i.e., windborne missile impacts followed by an extensive positive/negative pressure spectrum. Results indicated that the accelerated weathering had demonstrable effects on both the PVB laminated glass and the structural silicone anchor bead. However, complete resistance to glass fallout during the pressure spectrum was achieved when the inboard glass ply remained unbroken after completion of the windborne missile impacts.
Seismic Behavior of Structural Silicone Glazing
Authors: Zarghamee MS , Schwartz TA , Gladstone M
Published: March 2009

In seismic events, glass curtain walls undergo racking deformation, while the flat glass lites do not rack due to their high shear stiffness. If the glass curtain wall is not isolated from the building frame by specifically designed connections that accommodate relative motion, seismic racking motion of the building frame will demand significant resiliency of the sealant that secures the glass to the curtain wall framing. In typical four-sided structural silicone glazing systems used in buildings with unbraced moment frames, the magnitude of seismic racking is likely to stress the sealants significantly beyond the sealant design strength.

In this paper, the extent of the expected seismic racking motion, the behavior of the structural silicone glazing when subjected to the expected racking motion, and the field performance of a building with four-sided structural silicone glazing during the Northridge earthquake are discussed. The details of a curtain wall design concept consisting of shop-glazed subframes connected to the building frame and the connections that accommodate seismic motion of the subframe relative to the building frame is developed. Specific recommendations are made for the design of the four-sided structural silicone glazing systems for seismic loads.
Design Considerations for Sealants When Used at Horizontal Expansion Joints in Masonry Cavity Walls
Authors: O'Connor TF , Droz HL
Published: March 2009

Often, performance factors related to the design and materials used for flashing of masonry support members and the design of the support members themselves are inadequately considered in multistory masonry wall construction. This often results in inadequate conditions for installation of a sealant in the horizontal expansion joint below the support member, which can result in deficient sealant performance, lessened wall system durability, and water infiltration.

This paper will describe a tube and plate support member and its deflection, rotation and erection tolerances; and flashing materials and their durability. The effects of inadequate consideration of these components on the performance of the sealant joint in the horizontal expansion joint will be described; as well as, how to design the horizontal expansion joint for movement and other effects.
The Relative Effects of Deformation and Aging on Sealant Behavior
Authors: Margeson JL , Lacasse MA , Margeson JC
Published: March 2009

One-component polyurethane sealant specimens were cast between sections of aluminum substrate, cured at standard conditions for 21 days and then subjected to deformations ranging from 50% compression to 75% extension. Specimens were divided into three groups: one group remained at standard conditions, another group was mounted in a xenon arc weathering device and the remaining group was placed in a forced air oven. After 500 hours of exposure specimens were returned to standard conditions and then tested to failure. The sealant characteristics monitored were recovery from deformation, ultimate elongation, tensile strength, strain energy to break and the nature of the failure. Both elongation and strain energy were discriminating indicators of changes in the mechanical properties of the sealant The results indicate that prolonged compression markedly reduced the elongation capacity of the sealant, whereas prolonged extension produced specimens with higher elongation capacities. In most specimens, adhesive failure predominated; cohesive failure was evident in those specimens that had been extended and exposed to elevated temperatures. Five hundred hours of exposure were observed to be insufficient to cause significant chemical degradation of the sealant.
Effect of Cross-Sectional Shapes of Polysulfide Sealant on Fatigue Resistance to Joint Movement
Authors: Tanaka K , Hirai T , Koike M
Published: March 2009

The effect of cross-sectional shapes of polysulfide sealing beads on fatigue resistance to joint movement was studied experimentally and analytically. Five kinds of sealing beads that were different in the depth of their surface concavity were repeatedly extended and contracted by a fatigue machine. During the tests, cracks appeared around the corner or in the middle of the surfaces in some specimens. The time to cracking clearly became shorter on the specimens with deeper concave surfaces. To learn the reason for these results, the stresses along the surfaces of sealing beads were studied further using a boundary element method. It was concluded from the both experimental and analytical results that a durable cross-section of a sealing bead to fatigue is a slightly concave shape.
Evaluation and Modification of a Statistical Specification for Hot Mix
Authors: Metcalf JB , Ray TG
Published: March 2009

Louisiana's current statistically based specification system was initiated in 1967. This system was based upon contractor quality control and department acceptance testing using known variability concepts. A materials data base was also initiated at that time to archive materials test results and information. Since inception of the data base and system, major changes have been incorporated into the standard specifications. Further, there have been advances in equipment and operational control devices that can further reduce construction and test variation.

With these changes in mind and the presence of an excellent data base for analysis, this study was directed at updating the system to reflect current operations and to exert pressure for quality improvements where this was practicable. The study began with a statistical analysis of the data, collected for various plants and mix types and proceeded to establish a framework for revision of the specification and quality control system. Its conclusion will be with recommendations for changes that would facilitate the improvement of overall quality of the hot-mix asphaltic concrete.

It is believed that the procedures used, experience gained and knowledge developed by involved personnel will assist those with similar problems in reaching results which improve operations and quality of the final product in a timely manner.
Field Management of Hot Mix Asphalt Volumetric Properties
Authors: Kandhal PS , Foo KY , D'Angelo JA
Published: March 2009

The Federal Highway Administration (FHWA) Demonstration Project No. 74 has clearly shown that significant differences exist between the volumetric properties of the laboratory designed and plant produced hot mix asphalt (HMA) mixes. The volumetric properties include voids in the mineral aggregate (VMA) and the voids in the total mix (VTM). This project was undertaken to develop practical guidelines for the HMA contractors to reconcile these differences thereby assisting them to consistently produce high quality HMA mixes. The HMA mix design and field test data from 24 FHWA demonstration projects were entered into a database. The data included mix composition (asphalt content and gradation) and volumetric properties. The data were analyzed to identify and, if possible, quantify the independent variables (such as asphalt content and the percentages of material passing No. 200 and other sieves) significantly affecting the dependent variables (such as VMA and VTM).

Based on the preceding work, troubleshooting charts have been constructed to correct and reconcile differences between the volumetric properties of the job mix formula and the produced mix.
QC/QA Specifications—A Texas Producer's Experiences
Authors: Dukatz EL
Published: March 2009

The Texas Department of Transportation (TxDOT) has adopted QC/QA specifications for hot mix asphalt (HMA) projects. Under these specifications, the contractor is responsible for the HMA design and testing for pay-factors. The testing and pay-factors are broken into three areas: mixture, pavement density and smoothness. The contractor is also required to have a QC program to monitor the non-pay items of the job mix design. The contractor uses the data to make the decision to proceed, make corrections or shut down. The area TxDOT office is responsible for testing split samples taken by the contractor for acceptance. The TxDOT district laboratory is responsible for independent assurance samples. TxDOT, Division of Materials and Tests in Austin has been designated as the referee laboratory to settle any testing disputes not solved at the area office level.

This paper will summarize the construction of three QC/QA projects across Texas. The projects include Highway projects in Abilene and San Antonio and a project on I-20 near Eastland. The HMA used on these projects included a number of asphalt types and mixture designs. The projects used both polymer modified and conventional asphalts. The mixes used included both a dense graded surface mix as well as a coarse matrix high binder (CMHB) mix. The paper will also cover the problems and successes of mix design, testing which included using a nuclear asphalt content gage and communications.
Use of SHRP-Developed Testing in QC/QA Programs on Asphalt Concrete for Highway and Airfield Pavements
Authors: Harvey JT , Vallerga BA , Monismith CL
Published: March 2009

Present-day test equipment and procedures in quality control (QC) and quality assurance (QA) programs, based on use of the Marshall and Hveem methods, are essentially limited to verification of the physical composition of the asphalt concrete mix and its compacted density to control and assure that the builder is supplying a product which falls within the constraints defined by the job-mix-formula. They do not answer the essential question as to whether or not the asphalt concrete mix will have the strength properties needed to resist the number and intensity of repeated wheel load applications for which it was designed, both at the as-constructed and the traffic-compacted stages. This paper presents a philosophical discussion of the requirements for an asphalt concrete QC/QA system, using performance-based measures as the criteria. The framework for a performance-based system is described based on use of the Repetitive Simple Shear Test at Constant Height (RSST-CH) for rutting prediction and the Flexural Bending Beam Test (FBBT) for the estimation of fatigue cracking.
Performance Based Field Quality Control/Quality Assurance for Asphalt-Aggregate Mixes
Authors: Sousa JB , Way G , Bouldin MG , Harvey JT
Published: March 2009

The Arizona Department of Transportation in its continuing effort to improve pavement technology evaluated the use of the repetitive simple shear test at constant height and flexural bending beam test as part of the mix design and field quality assurance process. The results of the efforts, indicated that the use of those performance based tests and associated analysis procedures are feasible and implementable for routine use.
The Effect of Thermal Exposure on the Fracture Behavior of Aluminum Alloys Intended for Elevated Temperature Service
Authors: Reynolds AP , Crooks RE
Published: March 2009

Because of their ease of fabricability, durability, and good specific properties, precipitation-hardened aluminum alloys have been the materials of choice for subsonic aircraft for over 50 years. At the present time, precipitation-hardening alloys are being evaluated for use in elevated temperature applications such as supersonic transport aircraft. These applications require stability of mechanical properties, implying stable microstructures. In this study, it has been shown that for three materials of interest, microstructural evolution at relatively low temperatures may result in complex changes in mechanical properties with fracture resistance being a salient example. Changes in amounts and kinds of grain boundary fracture, probably related to growth of grain boundary precipitate phases or segregation of embrittling species to the boundaries, appear to dominate the behavior.
Thermomechanical Fatigue Behaviour of Coated and Bare Nickel-Based Superalloy Single Crystals
Authors: Chataigner E , Remy L
Published: March 2009

The thermal-mechanical fatigue behaviour of chromium-aluminium coated [001] single crystals of AM1, a nickel-base superalloy for turbine blades, is studied using a “diamond” shape cycle from 600‡ to 1100‡C. Comparison with bare specimens does not show any significant difference in thermal-mechanical fatigue nor in isothermal low cycle fatigue at high temperature. Metallographic observations on fracture surfaces and longitudinal sections of specimens tested to fatigue life or to a definite fraction of expected life have shown that the major crack tends to initiate from casting micropores in the sub-surface area very early in bare and coated specimens, under low cycle fatigue or thermal-mechanical fatigue. But the interaction between oxidation and fatigue cracking seems to play a major role. A simple model proposed by Reuchet and Rémy has been identified for this single crystal superalloy. Its application to the life prediction under low cycle fatigue and thermal-mechanical fatigue for bare and coated single crystals with different orientations is shown.
Effects of Cycle Type and Coating on the TMF Lives of a Single Crystal Nickel Based Gas Turbine Blade Alloy
Authors: Bressers J , Timm J , Williams SJ , Bennett A , Affeldt EE
Published: March 2009

Strain controlled thermo-mechanical fatigue cycles simulating the temperature-strain-time history at critical locations of blades of advanced aero gas turbines are applied to the single crystal nickel based alloy SRR99 in the uncoated and aluminide coated conditions. The TMF cycle selection includes a −135‡lag cycle and an in-phase cycle, with various R-ratios, Tmin=300‡C, and Tmax=1050‡C and 850‡C, respectively. The cycle-specific stress response is analyzed and discussed in terms of the accumulation of inelastic strain during the TMF tests, and the inelastic strain build-up is correlated with the cyclic hardening / softening behaviour. The number of cycles for initiating microcracks is measured by means of a computer vision system. Various modes of crack initiation and crack growth are observed and correlated with the TMF cycle type, with the strain range imposed, and with the ductile/brittle behaviour of the coating. The differences in TMF lives are discussed in terms of the material and TMF parameters
Thermomechanical Fatigue Damage Mechanism Maps for Metal Matrix Composites
Authors: Neu RW
Published: March 2009

Thermomechanical fatigue (TMF) damage mechanism and life maps are generated for unidirectional SCS-6/Timetal 21S undergoing repeated uniaxial loadings oriented along the fiber direction. The maps show the constant life contours as well as the dominant damage mechanisms as a function of maximum cyclic temperature and maximum applied cyclic stress. The maps are constructed using models that describe the individual damage mechanisms. Presently, the damage models include time, temperature, and stress-temperature phasing dependencies but are limited to repeated uniaxial loadings with constant amplitudes and positive stress ratios. Both in-phase and out-of-phase TMF maps are constructed with maximum cyclic temperatures ranging from 300‡ to 900‡C and maximum applied cyclic stresses ranging from 0 to 2000 MPa. The temperature range, stress ratio, and cycle period (500‡C, 0.1, 3 min., respectively) are held constant. In addition, maps are generated for isothermal fatigue using the same stress ratio and cycle period. The maps are useful for giving the overall picture of the TMF behavior over a wide range of stress and temperature combinations. The connection between TMF and isothermal fatigue is illustrated.
Time- and Cycle-Dependent Aspects of Thermal and Mechanical Fatigue in a Titanium Matrix Composite
Authors: Nicholas T , Johnson DA
Published: March 2009

Specimens of SCS-6/Timetal®21S in [0]4 and [0/90]S orientations were subjected to three types of tests covering temperatures of 650, 760, and 815‡C. In the first, low frequency cycles with no superimposed hold times were applied. In the second, low frequency fatigue cycles were applied with superimposed hold times of various durations at maximum loads. In the third, hold times were superimposed at minimum load. In all tests, the number of cycles to failure was recorded. The behavior of the composite in these tests was modeled by considering damage to consist of a linear sum of a cycle-dependent component and a time-dependent component. It was found that the behavior in all tests was basically time dependent Using time at temperature and stress as a failure criterion, it is shown that data from creep, low frequency fatigue with and without hold times, and in-phase thermomechanical fatigue tests can be consolidated for all [0]4 tests into a single curve and for all [0/90]S tests into a different curve. Both curves can be explained in terms of a single fiber bundle strength value by considering the time-dependent behavior of the matrix material. Additionally, hold times at minimum load are found to be more detrimental to fatigue life than identical tests where the hold time is applied at the maximum load.
Modeling the Crack Growth Rates of a Titanium Matrix Composite Under Thermomechanical Fatigue
Authors: Blatt D , Nicholas T , Grandt AF
Published: March 2009

The crack growth characteristics of a 4-ply, unidirectional, titanium matrix composite, SCS-6/Ti-6Al-2Sn-4Zr-2Mo, subjected to thermomechanical fatigue were investigated. A linear summation model was developed to predict the isothermal and thermomechanical fatigue (TMF) crack growth rates of the composite. The linear summation approach assumes the total fatigue crack growth rate is a combination of a cycle-dependent and a time-dependent component. To assist the modeling effort, a series of isothermal, in-phase, and out-of-phase crack growth tests were conducted. The test temperatures ranged from 150‡C to 538‡C and the fastest thermal frequency was 0.0083 Hz. With the exception of the 150‡C isothermal test, the model was able to correlate all the baseline fatigue crack growth test data between δK of 50 to 90 MPa √m. In addition, the model was able to predict the fatigue crack growth rate of a proof test which involved a continual change in temperature range and load range to produce a constant crack growth rate. The proof test began under isothermal conditions at the maximum temperature and ended under in-phase TMF conditions.
Irradiation Embrittlement Modelling of Linde 80 Weld Metals
Authors: McElroy RJ , Lowe AL
Published: March 2009

Linde 80 weld metals are characterised by a narrow range of chemical compositions, except for copper content, which varies from 0.2–0.42 wt%. The surveillance database for Linde 80 weld metals constitutes a unique and large database on a single class of material for evaluating embrittlement models and property correlations used in the assessment of RPV embrittlement.

Correlations between Charpy transition temperature shifts and yield strength, which best characterises the hardening behaviour, were tested and it was concluded that fracture appearance transition temperature (FATT) provided less scatter and a more representative indicator than either lateral expansion or Charpy 30 ft-lb energy. This is believed to be a consequence of the low upper shelf of Linde 80 weld metals distorting the latter two transition temperatures, especially after irradiation, which induces a significant reduction in upper-shelf to levels approaching the indexing values.

The main purpose of the present study has been to obtain a simple two component barrier hardening model form which best describes the behaviour of Linde 80 weld metal. To this end, the UK Magnox Embrittlement Model, often referred to as the Fisher Model, has been used and the key parameters, such as activation energies, dislocation densities and damage cross sections, were used as fitting parameters. Good agreement was found between model predictions and the surveillance yield strength data following optimisation of model parameters. Applying the latter optimised form produced equally good prediction of HSSI results at a significantly higher damage rate demonstrating the “rate effect” inherent in the irradiation enhanced copper precipitation process. The best agreement was obtained assuming a matrix copper content of about 0.23 wt% which is consistent with recent solubility data for Linde 80 welds. For these materials an insensitivity to bulk copper content was demonstrated even though this varied from 0.21–0.42 wt%. Additionally, the parameters optimised for high copper welds provided a good prediction for low-copper materials indicating that the matrix hardening component was correctly specified. The low matrix hardening and predicted completion of copper precipitation by doses of about 1×1019ncm−2 support the notion of embrittlement saturation at high doses.
Mitigation of Irradiation Embrittlement by Annealing
Authors: Amayev AD , Kryukov AM , Levit VI , Platonov PA , Sokolov MA
Published: March 2009

The main results of a complex investigation carried out in Russia of post irradiation annealing and reembrittlement of WWER-440 reactor pressure vessel materials are presented. The dependence of the Charpy transition temperature recovery on annealing temperature and fluence was established. Charpy specimens were reirradiated after annealing at 340, 380, 420, and 460°C. Experimental values of the Charpy transition temperature after reirradiation are compared to that predicted by three methods. At annealing temperatures equal to or above 420°C, results of the analysis indicate that, of the methods investigated, the “lateral shift” method gives the best result for estimating the transition temperature shift due to reirradiation.
Microstructure and Mechanical Properties of WWER-440 Reactor Vessel Metal After Service Life Expiration and Recovery Anneal
Authors: Gorynin IV , Nesterova EV , Nikolaev VA , Rybin VV
Published: March 2009

The microstructure of base and weld metals (st.15Kh2MFA) of Novovoronezh Nuclear Power Plant Units 1 and 4 reactor vessels was studied after service life expiration and recovery anneal by means of light metallography and transmission electron microscopy. The qualitative characteristics of flow structure were determined. The estimates were made for the contributions of different flows to the radiation hardening and its total value. The conclusion was made that the marked difference in the mechanical properties of irradiated weld and base metals can be caused either by different original structure conditions or by the difference of alloying and impurity elements content.
The Reconstitution of Charpy-Size Tensile Specimens
Authors: Van Ransbeeck T , Van Walle E , Fabry A , Puzzolante JL , Van de Velde J
Published: March 2009

Charpy-size tensile specimens have been reconstituted starting from broken Charpy specimens. Precautions have been taken to prevent fracture in the weld regions of the reconstituted specimens.

Careful qualification of the tensile properties of the reconstituted tensile bars has been established and is in agreement with test results on ASTM/E8-size tensile specimens. The tensile properties of the unirradiated weld material of the Belgian PWR Doel 2 and of the unirradiated base metal of the German BWR Philippsburg 1 have been determined using this methodology. Both the resulting yield and maximum loads are in agreement with the actual expectations.

Qualification to apply the technique on irradiated specimens is in preparation.
Notch Reorientation of Charpy-V Specimens of the BWR Philippsburg 1 Through Reconstitution
Authors: van Walle E , Fabry A , Van Ransbeeck T , Puzzolante J-L , Van de Velde J , Tulke K , Backfisch W
Published: March 2009

10×10×10mm cubes, made from broken halves of un-irradiated and irradiated L-T oriented Charpy-V surveillance specimens of the Boiling Water Reactor (BWR) Philippsburg 1, were reconstituted to L-T and T-L oriented Charpy-V bars using the studgun welding technique of the Belgian Nuclear Research Centre SCK•CEN. Instrumented Charpy-V (CV) impact testing, according to the European Standard EN 10045, was performed in order to determine the T-L transition curves of the reconstituted surveillance material. Losses of fracture energy and lateral expansion, mainly as a consequence of constraint of plastic flow due to the reconstitution welds, were detected. No change in shear fracture appearance was observed. The transition curves of the tested T-L reconstituted specimens represent conservative lower bounds that fulfil the CV upper shelf energy requirements of the Regulator. A correction curve allows estimation of the T-L transition curves of non-reconstituted T-L specimens.

The data were consistently analysed with hyperbolic tangent functions, while the load diagram recorded during the instrumented impact tests was used for guidance in the analysis. The quality assurance (QA) was ensured by the ‘Technischer Uberwachungs-Verein Süd-westdeutchland’ (TüV-Südwest), ‘Staatliche Materialprüfungsanstalt Universitat Stuttgart’ (MPA-Stuttgart) and ‘Kernkraftwerk Philippsburg’ (KKP).
Surveillance Programme for WWER-440/Type 213 Reactor Pressure Vessels- Standard Programme, Re-Evaluation of Results, Supplementary Programme
Authors: Brumovský M , Novosad P , Žd'árek J
Published: March 2009

Irradiation embrittlement of the reactor pressure vessel beltline materials of WWER-440/Type 213 reactors is monitored by a material irradiation surveillance programme. Due to the high lead factor, the duration of the standard surveillance programme is only five years, after which no further surveillance samples remain in the reactor. The large variation and uncertaintity in neutron flux over the irradiated materials produce significant scatter in mechanical properties and necessitate a re-evaluation of results using gamma scanning, specimen reconstitution and recalculation. In order to provide information on the impact of changes in plant operation during later years a supplementary surveillance programme has been devised.
HFIR Steels Embrittlement: The Possible Effect of Gamma Field Contribution
Authors: Remec I , Wang >J-A , Kam FBK
Published: March 2009

Recent comprehensive dosimetry experiments revealed the presence of an intense gamma field at the High Flux Isotope Reactor (HFIR) surveillance locations near the pressure vessel. Measured responses of fission dosimeters 238U and 237Np, as well as 9Be helium accumulation fluence monitors were placed in accordance with responses of threshold and thermal neutron activation dosimeters only when photofission and photo-neutron reactions, respectively, were taken into account. Gamma-flux (E > 1MeV)-to-neutron-flux (E > 1MeV) ratios as high as 104 were observed.

It has been generally accepted that neutron interactions with materials are the main cause of changes in mechanical properties of ferritic steels in nuclear reactor environments. However, gamma rays can also create displaced atoms that can in turn contribute to material embrittlement. Gamma-induced displacements may be quite negligible when compared with neutron-induced displacements in most irradiations, and need not be taken into account. However, at the HFIR surveillance position the gamma-induced atom displacement rate dominates or at least equals the neutron-induced atom displacement rate. When the sum of neutron- and gamma-induced displacements per atom is used as an irradiation exposure parameter the HFIR surveillance results are in agreement with other test reactor results. The “accelerated embrittlement” phenomenon, therefore, appears to be caused by the previously unaccounted atomic displacements induced by gamma rays. However, independent verification that gamma-induced displacements can cause material embrittlement is necessary.
The Effect of Constraint on Toughness of a Pressure Vessel Steel
Authors: Edsinger K , Odette GR , Lucas GE , Wirth B
Published: March 2009

One-third-sized pre-cracked Charpy bars (MPCC, a/W ~ 0.5) were tested over a range of temperatures. Initiation by unstable fracture or extensive pop-in/arrest events took place in the low and intermediate temperature/toughness regime; at higher temperatures/toughness levels, crack growth was limited to blunting/local damage. The small specimen toughness curve is shifted down in temperature and has steeper transition slopes compared with data for larger compact tension (CT) specimens from the literature. Full size pre-cracked Charpy (PCC) specimens with a/W ratios of nominally 0.1 and 0.5 were tested at −73°C. The toughness for PCCs with a/W = 0.1 was higher by factors of 2 to 4. Confocal microscopy (CM), fracture reconstruction (FR) and finite element method (FEM) simulations were used to evaluate the local conditions at cleavage fracture. For a/W = 0.5 (PCC and MPCC), initiation took place at a single critical stress-critical area criteria independent of size and temperature. However, for the a/W = 0.1 specimens, the critical stress was lower with a correspondingly larger critical area. This is consistent with the reduced stress field present in shallow cracks. Failure by cleavage initiation at a lower critical stress is tentatively attributed to the effects of higher local strains modifying cleavage conditions.
The Effects of Thermal Annealing on Fracture Toughness of Low Upper-Shelf Welds
Authors: Sokolov MA , Nanstad RK , Iskander SK
Published: March 2009

Experimental results are presented from a study of the effects of thermal annealing on recovery of fracture toughness of low upper-shelf submerged-arc welds (weld designations 61W through 67W) from the Heavy-Section Steel Irradiation (HSSI) Program Second and Third Irradiation Series. Most of the study was conducted to evaluate the effects of annealing on the J-R curves of the submerged-arc welds. The recovery of fracture toughness in the transition range as the result of annealing was studied for welds 63W, 64, and 65W only. Compact specimens of 12.7- and 20.3-mm-thick (0.5T and 0.8T, respectively) were tested in this study. The specimens had been previously irradiated at the Oak Ridge National Laboratory (ORNL) Bulk Shielding Reactor. Each weld was irradiated to a certain value of neutron fluence in the range from 0.4 to 1.3 × 1019 neutrons/cm2 (> 1 MeV) in the average temperature range of 275 to 300°C. Annealing of the irradiated specimens was done at 454°C for 168 h. Fracture toughness tests were performed at temperatures selected to match those of the previously conducted unirradiated and irradiated tests.
The Microstructural Stability and Mechanical Properties of Two Low Activation Martensitic Steels
Authors: Victoria M , Batawi E , Briguet C , Gavillet D , Marmy P , Peters J , Rézai-Aria F
Published: March 2009

A low activation composition of a martensitic 9 % Cr steel has been studied, based on the DIN (Deutsches Institiit für Normung) 1.4914 composition (MANET) but replacing Ni, Mo and Nb by the low activation elements W, V and Ta. Two casts were produced from high purity components, in which the effects of controlled additions of Mn (0.58 and 0.055 wt. %) and N (7 and 290 wt. ppm) were studied, so that the final compositions resulted in one cast with high Mn and low N (steel A) and the other with the opposite conditions (steel B). The two steels were evaluated in terms of structural stability and mechanical properties under tensile, fatigue and fracture toughness tests.

It has been found that both alloys have a DBTT below room temperature, which in the case of the steel A is 70 K below that of MANET. Although the tensile strength is somewhat below that of the parent steel, both steels have longer fatigue life.
Evaluation of the Upper Shelf Energy for Ferritic Steels from Miniaturized Charpy Specimen Data
Authors: Kurishita H , Shibahara I , Narui M , Mizuta S , Kayano H
Published: March 2009

In order to develop the methodology to evaluate the upper shelf energy (USE) for full size Charpy specimens of ferritic steels from miniaturized specimen data, the effects of specimen size and notch dimensions (notch root radius and notch depth) on the USE were studied for high strength ferritic steels with relatively low USE values of 135 and 107 J. The USE for miniaturized specimens, normalized by Bb 2 or (Bb)3/2 (B is the specimen thickness, b is the ligament size), was essentially independent of specimen size and tended to decrease with increasing the elastic stress concentration factor, Kt, but the Kt dependence was not significant. The normalized USE for full size specimens was considerably lower than that for miniaturized specimens. A general relationship was found that allows to determine the USE of full size specimens of ferritic steels directly from miniaturized specimen data.
On the Role of Strain Rate, Size and Notch Acuity on Toughness: A Comparison of Two Martensitic Stainless Steels
Authors: Lucas GE , Odette GR , Edsinger K , Wirth B , Sheckherd JW
Published: March 2009

The fracture resistance and micromechanisms of two tempered martensitic steels were characterized over a range of temperatures by both mechanical testing and quantitative fractography. HT-9 and F-82H undergo a fracture mode transition from quasi-cleavage at low temperature to microvoid coalescence at high temperature. The transition in HT-9 is rather gradual, and the transition in F-82H is extremely abrupt. While the toughness of F-82H was higher in all cases, differences between the two steels depended on test type, strain rate and temperature. The results not only demonstrate the inherent non-uniqueness of the so called ductile-to-brittle transition temperature (DBTT), but also call into question the use of Charpy data for ranking the relative performance of various alloys. The similarities in quasi-cleavage fracture and differences in ductile fracture are manifested in the fracture surfaces and are interpreted in terms of the underlying mechanisms and microstructures.
Fracture Toughness of Irradiated Candidate Materials for ITER First Wall/Blanket Structures
Authors: Alexander DJ , Pawel JE , Grossbeck ML , Rowcliffe AF , Shiba K
Published: March 2009

Disk compact specimens of candidate materials for first wall/blanket structures in ITER have been irradiated to damage levels of about 3 dpa at nominal irradiation temperatures of either 90 or 250°C. These specimens have been tested over a temperature range from 20 to 250°C to determine J-integral values and tearing moduli. The results show that irradiation at these temperatures reduces the fracture toughness of austenitic stainless steels, but the toughness remains quite high. The toughness decreases as the test temperature increases. Irradiation at 250°C is more damaging than at 90°C, causing larger decreases in the fracture toughness. Ferritic-martensitic steels are embrittled by the irradiation, and show the lowest toughness at room temperature.
Helium Effects on the Reweldability and Low Cycle Fatigue Properties of Welded Joints for Type Cr16Ni11Mo3Ti and 316L(N) Stainless Steels
Authors: Fabritsiev SA , van der Laan JG
Published: March 2009

The reweldability of austenitic alloys has been studied for flat specimens of Cr16NillMo3Ti (Russian) and 316L(N)-SPH (European Union) which have been implanted with helium using cyclotron facilities. Specimens with typical thicknesses of 1 mm have been implanted up to helium concentrations of 50, 100, 300 and 860 appm on both sides. Electron beam welding of Cr16NillMo3Ti resulted in weld cracking for specimens with the highest helium concentration of 860 appm, unlike the 316L-SPH material in similar conditions. A reduction in fatigue life in low cycle fatigue was found to be more significant for welded joints of Cr16NillMo3Ti material.
Effect of Irradiation in a Spallation Neutron Environment on Tensile Properties and Microstructure of Aluminum Alloys 5052 and 6061
Authors: Dunlap JA , Borden MJ , Sommer WF , Stubbins JF
Published: March 2009

The Accelerator Production of Tritium (APT) and the Accelerator Transmutation of Waste (ATW) programs require structural materials which retain good mechanical properties when exposed in a spallation neutron irradiation environment. One group of materials likely to withstand the environment anticipated for these systems is the aluminum alloy series. To characterize this class of materials in a prototypical irradiation environment, Al5052 (Al-2.7Mg) and Al6061 (Al-1.1Mg-0.5Si) in hardened and annealed conditions were irradiated to a fluence of 4.2×1020 neutrons/cm2 at ~100°C in a spallation neutron source. Following irradiation, tensile tests and post-test examinations were performed to determine the influence of irradiation and test temperature on mechanical properties and fracture mode. It was found that, the properties of these two aluminum alloys were not significantly affected by the irradiation exposure conditions examined here. Thus these materials may be acceptable as structural materials for APT and ATW applications. This conclusion is based on limited mechanical properties testing, supported by other information in the literature on the performance of these materials in other irradiation environments.
Correlation Between Shear Punch and Tensile Data for Neutron-Irradiated Aluminum Alloys
Authors: Hamilton ML , Toloczko MB , Edwards DJ , Sommer WF , Borden MJ , Dunlap JA , Stubbins JF , Lucas GE
Published: March 2009

As part of a study to determine the potential for using aluminum alloys as structural components in accelerators used to produce tritium, tensile specimens and transmission electron microscopy (TEM) disks of two aluminum alloys in two tempers were irradiated with neutrons from spallation reactions in the Los Alamos Spallation Radiation Effects Facility (LASREF) at the Los Alamos Meson Physics Facility (LAMPF) at 90 to 120°C to a fluence of ~4×1020 n/cm2. Tensile and shear punch tests were performed on the irradiated alloys as well as on a similar unirradiated control matrix with a larger number of specimens, and a correlation between shear and tensile properties was developed for the unirradiated alloys and the irradiated alloys. Comparison of the correlations for the unirradiated and irradiated alloys showed that small differences in the correlations existed, however for purposes of estimation of uniaxial tensile properties, either correlation was found to be adequate.
Effect of Dynamically Charged Helium on Mechanical Properties of Vanadium-Base Alloys
Authors: Chung HM , Loomis BA , Smith DL
Published: March 2009

One property of vanadium-base alloys that is not well understood in terms of their potential use as fusion reactor structural materials is the effect of simultaneous generation of helium and neutron damage under conditions relevant to fusion reactor operation. In the present Dynamic Helium Charging Experiment (DHCE), helium was produced uniformly in the specimen at linear rates ranging from≈0.4 to 4.2 appm helium/dpa during irradiation to 18–31 dpa at 425–600°C in the Li-filled capsules. Results of postirradiation tests of mechanical properties of V-4Cr-4Ti, an alloy identified to be most promising, are presented. Effects of helium on tensile strength and ductility at 420–600°C were insignificant for irradiation at these temperatures. However, postirradiation ductilities measured at 20–200°C were higher than those of the non-DHCE specimens (negligible helium generation), whereas strengths were lower, indicating that different types of hardening centers were produced during DHCE and non-DHCE. Ductile-brittle transition behavior of the DHCE specimens was determined from multiple bend tests on TEM disks and broken tensile specimens. No brittle behavior was observed at temperatures >-175°C. In contrast to tritium-trick experiments in which grain-boundary coalescence of helium is pronounced in the absence of displacement damage, no intergranular fracture was observed in tensile or bend-tested DHCE specimens.
Characterization of Irradiation-Induced Precipitates by Small Angle X-Ray and Neutron Scattering Experiments
Authors: Gro\e M , Eichhorn F , Böhmert J , Brauer G
Published: March 2009

The nature of the irradiation-induced precipitates in the VVER-440-type steel 15Kh2MFA has been investigated by the combination of small angle neutron scattering and anomalous small angle X-ray scattering. Information about the chemical composition of the irradiation-induced precipitates was obtained by the method of contrast variation. ASAXS experiments with variation of the X-ray energy near the energy of the vanadium K-absorption edge prove the content of vanadium within the irradiation-induced precipitates. The scattering density of the precipitates is lower than the scattering density of the iron matrix. The chemical shift of the vanadium-Kα-absorption-edge and the results of the variation of the contribution of the magnetic scattering in the SANS experiment show, that vanadium does not precipitate in an elementary state. These results can be explained by assuming the precipitates are vanadium carbide.
Use of Laser Extensometer for Mechanical Tests on Irradiated Materials
Authors: Brillaud C , Meylogan T , Salathe P
Published: March 2009

Techniques have been developed by EDF's hot laboratory in Chinon for performing mechanical tests on irradiated materials. Some of these techniques aim to facilitate strain measurements, which are particularly difficult to perform on irradiated specimens at high temperatures or on subsize specimens.

Recent progress has been driven by laser technology combined with software development. The use of this technique, which allows strain measurements without contact on the specimen, is described for tensile (especially on subsize specimens), fatigue and creep tests.
Characterization of Heat Damage in Graphite/Epoxy Composites
Authors: Armstrong-Carroll E , Mehrkam PA , Cochran R
Published: March 2009

Polymer-matrix composite materials are currently in use as structural components on aircraft. These composites may be subjected to heat damage during their service life. This damage can arise from a fire, engine exhaust, or a mishap during a composite repair. The high-temperature exposure times corresponding to these incidents are typically less than 5 min. When heat damage is severe, the damage can be detected using visual or ultrasonic techniques. However, there is a concern that moderate amounts of heat damage that cannot be detected with ultrasonic or visual inspection may cause a decrease in the physical or mechanical properties of the composite.

In this study, panels were damaged at a moderate temperature for exposure times of 1 to 5 min and at a high temperature for exposure times of 5 to 30 s. A full spectrum of undamaged, moderate, and severe heat damage was constructed from these exposures. The control and heat-exposed panels were characterized with visual inspection, ultrasonics, hardness, and flexural strength measurements. With the heat-exposed panels, reductions in properties occurred only in coupons that possessed delaminations that were detected by ultrasonics.