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Thermal fatigue of ductile materials 2: effect of cyclic thermal stressing on the stress-rupture life and ductility of S-816 and Inconel 550

Description: Report presenting an experimental study of the changes in the stress-rupture life, ductility, hardness, and microstructure of S-816 and Inconel 550 specimens that had been exposed to varying amounts and conditions of thermal fatigue. Exposure to thermal-fatigue conditions was found to strengthen S-816 in stress rupture and to weaken Inconel 550.
Date: September 1958
Creator: Clauss, Francis J. & Freeman, James W.
Partner: UNT Libraries Government Documents Department

Consequences of return to power after a beam interruption in the blanket of an accelerator driven system.

Description: A sudden drop in power after a beam interruption leads to thermal fatigue effects in structural components in the blanket of an accelerator driven system. These thermal fatigue effects limit component lifetimes. A sudden return to power after a beam interruption can contribute significant additional thermal fatigue and greatly reduce component lifetimes. One obvious solution is a gradual return to power after a beam interruption. There are two potential problems with this solution. One problem involves interruptions that are longer than the thermal time constants of thin structural members but shorter than the time constants of thick structural members. In such a case, a gradual return to power reduces the additional thermal fatigue in the thin structural members but increases the thermal fatigue in thick structural members. Some compromise is necessary. The other problem is that for thick components with long thermal time constants a long, gradual return to power is required to minimize additional thermal fatigue. Such a slow return to power can reduce the utilization or the effective load factor of the system. Specific examples of beam interruptions with various assumptions on return to power are provided for a preliminary design for the blanket of the Accelerator Driven Test Facility. Also, mitigation options to increase component lifetime are discussed. These mitigation options include improving beam reliability and modifying the blanket design to better tolerate beam interruptions.
Date: August 9, 2001
Creator: Dunn, F.
Partner: UNT Libraries Government Documents Department

Simulation and Experiment of Thermal Fatigue in the CPV Die Attach: Preprint

Description: FEM simulation and accelerated thermal cycling have been performed for the CPV die attach. Trends in fatigue damage accumulation and equivalent test time are explored and found to be most sensitive to temperature ramp rate. Die attach crack growth is measured through cycling and found to be in excellent agreement with simulations of the inelastic strain energy accumulated. Simulations of an entire year of weather data provides for the relative ranking of fatigue damage between four cites as well as their equivalent accelerated test time.
Date: May 1, 2012
Creator: Bosco, N.; Silverman, T. & Kurtz, S.
Partner: UNT Libraries Government Documents Department

Low Cycle Fatigue Analysis of Storage Canisters Due to Expansion of Contents

Description: Qualification of storage canisters due to the expansion behavior of plutonium metal during phase transitions requires a combined experimental and analytical modeling effort. Tests were conducted at Los Alamos National Laboratory to define the expansion behavior of plutonium metal during the alpha-beta-gamma phase transitions. Test results showed that the expansion is anisotropic due to the container wall constraint. The plutonium expansion parameters were calculated from test data, and combined with a finite element analysis to determine the stress state of the storage canisters. Strain values were computed and compared with the ASME Code secondary and peak stress limits. Since the applied expansion strain exceeds the strain of 10 cycles in the ASME Code design fatigue curve, the ASME Code design fatigue curve was extended to values below 10 cycles.
Date: December 12, 2003
Creator: Flanders, H.E. Jr.
Partner: UNT Libraries Government Documents Department

Effect of composition and processing on the thermal fatigue and toughness of high performance die steels. Final report

Description: The objective of this study was to improve average die life by optimizing die steel composition and the die processing. Four different steels, K,Q,C and Premium Grade H-13 have been investigated for thermal fatigue resistance and toughness. Optimum heat treatment processing has been determined for each steel with respect to austenitizing temperature and tempering conditions. The effect of the quenching rate on the thermal fatigue resistance and toughness of the die steels and the effect of Electro-Discharge Machining (EDM) on the thermal fatigue resistance were also determined. The immersion thermal fatigue specimen developed at CWRU was used to determine the thermal fatigue resistance as characterized by the two parameters of average maximum crack length and total crack area. The Charpy V-notch impact test was used over a -100{degrees}F to 450{degrees}F testing temperature range to evaluate the toughness and the brittle-ductile transition behavior. K steel has been identified as superior in performance compared to Premium Grade H-13. Q and C provide lower toughness and thermal fatigue resistance than H-13. Faster cooling rates provide higher thermal fatigue resistance and toughness. Higher austenitizing temperatures such as 1925{degrees}F compared to 1875{degrees}F provide better thermal fatigue resistance, but lower austenitizing temperatures of 1875{degrees}F provide better toughness. Higher hardness improves thermal fatigue resistance, but reduces toughness. A minimum of Rc 46 hardness is desired for aluminum die casting dies. EDM reduces the thermal fatigue resistance compared to conventional machining operations. When the EDM process of multiple small steps of decreasing energy and post-EDM treatments are employed, the effect can be reduced to a very slight amount. Preliminary evidence of the superior performance of the K steel has been provided by ongoing field testing of inserts in multiple cavity dies.
Date: June 1, 1997
Creator: Wallace, J.F.; Wang, Y. & Schwam, D.
Partner: UNT Libraries Government Documents Department

Thermal fatigue testing of a diffusion-bonded beryllium divertor mock-up under ITER relevant conditions

Description: Thermal response and thermal fatigue tests of four 5 mm thick beryllium tiles on a Russian divertor mock-up were completed on the Electron Beam Test System at Sandia National Laboratories. The beryllium tiles were diffusion bonded onto an OFHC copper saddleblock and a DSCu (MAGT) tube containing a porous coating. Thermal response tests were performed on the tiles to an absorbed heat flux of 5 MW/m{sup 2} and surface temperatures near 300{degrees}C using 1.4 MPa water at 5.0 m/s flow velocity and an inlet temperature of 8-15{degrees}C. One tile was exposed to incrementally increasing heat fluxes up to 9.5 MW/m{sup 2} and surface temperatures up to 690{degrees}C before debonding at 10 MW/m{sup 2}. A third tile debonded after 9200 thermal fatigue cycles at 5 MW/m{sup 2}, while another debonded after 6800 cycles. In all cases, fatigue failure occurred in the intermetallic layers between the beryllium and copper. No fatigue cracking of the bulk beryllium was observed. During thermal cycling, a gradual loss of porous coating produced increasing sample temperatures. These experiments indicate that diffusion-bonded beryllium tiles can survive several thousand thermal cycles under ITER relevant conditions without failure. However, the reliability of the diffusion bonded Joint remains a serious issue.
Date: December 31, 1994
Creator: Youchison, D.L.; Guiniiatouline, R. & Watson, R.D.
Partner: UNT Libraries Government Documents Department

Thermal response of the multiplier of an accelerator driven system to beam interruptions.

Description: Thermal response of the multiplier of an accelerator driven system to beam trips has been calculated for sodium cooled and lead-bismuth cooled multipliers. The temperature transients caused by a beam trip lead to thermal fatigue in structural components, and restoring the beam causes an additional temperature transient that adds to thermal fatigue. Design lifetimes for various multiplier components are calculated, based on the frequency of beam interruptions and on the thermal fatigue per interruption. Mitigation strategies to increase design lifetimes are discussed.
Date: May 15, 2002
Creator: Dunn, F. E.
Partner: UNT Libraries Government Documents Department

COMBUSTION TURBINE (CT) HOT SECTION COATING LIFE MANAGEMENT

Description: The integrity of coatings used in hot section components of combustion turbines is crucial to the reliability of the buckets. This project was initiated in recognition of the need for predicting the life of coatings analytically, and non-destructively; correspondingly, four principal tasks were established. Task 1, with the objective of analytically developing stress, strain and temperature distributions in the bucket and thereby predicting thermal fatigue (TMF) damage for various operating conditions; Task 2 with the objective of developing eddy current techniques to measure both TMF damage and general degradation of coatings and, Task 3 with the objective of developing mechanism based algorithms. Task 4 is aimed at verifying analytical predictions from Task 1 and the NDE predictions from Task 3 against field observations.
Date: March 31, 2006
Creator: Gandy, D.; Viswanathan, R.; Cheruvu, S. & Krzywosz, K.
Partner: UNT Libraries Government Documents Department

Analysis of Pressurized Water Reactor Primary Coolant Leak Events Caused by Thermal Fatigue

Description: We present statistical analyses of pressurized water reactor (PWR) primary coolant leak events caused by thermal fatigue, and discuss their safety significance. Our worldwide data contain 13 leak events (through-wall cracking) in 3509 reactor-years, all in stainless steel piping with diameter less than 25 cm. Several types of data analysis show that the frequency of leak events (events per reactor-year) is increasing with plant age, and the increase is statistically significant. When an exponential trend model is assumed, the leak frequency is estimated to double every 8 years of reactor age, although this result should not be extrapolated to plants much older than 25 years. Difficulties in arresting this increase include lack of quantitative understanding of the phenomena causing thermal fatigue, lack of understanding of crack growth, and difficulty in detecting existing cracks.
Date: September 1, 1999
Creator: Atwood, Corwin Lee; Shah, Vikram Naginbhai & Galyean, William Jospeh
Partner: UNT Libraries Government Documents Department

Effect of composition and processing on the thermal fatigue and toughness of high performance die steels. Year 1 report

Description: The goal of this project is to extend the lifetime of dies for die casting by 20%. Since the die contributes about 10% to the cost of die cast parts, such an improvement in lifetime would result in annual savings of over $200 Million dollars. This is based on the estimated annual die production of one Billion dollars in the US. The major tasks of this two year project are: (1) Evaluate NEW DIE STEEL COMPOSITIONS that have been developed for demanding applications and compare them to Premium Grade H-13 die steel. (2) Optimize the AUSTENITIZING TREATMENT of the new composition. Assess the effects of fast, medium and slow COOLING RATES DURING HEAT TREATMENT, on the thermal fatigue resistance and toughness of the die steel. (3) Determine the effect of ELECTRO-DISCHARGE MACHINING (EDM) on the thermal fatigue resistance and impact properties of the steel. (4) Select demanding components and conduct IN-PLANT TESTING by using the new steel. Compare the performance of the new steel with identical components made of Premium Grade H-13. The immersion thermal fatigue specimen developed at CWRU is being used to determine resistance to heat checking, and the Charpy V-notch test for evaluating the toughness. The overall result of this project will be identification of the best steel available on the market and the best processing methods for aluminum die casting dies. This is an interim report for year 1 of the project.
Date: June 1, 1996
Creator: Wallace, J.F.; Wang, Yumin & Schwam, D.
Partner: UNT Libraries Government Documents Department

Analysis of cracking of co-extruded recovery boiler floor tubes

Description: Cracking of the stainless steel layer in co-extruded 304L/SA210 tubing used in black liquor recovery boilers is being found in an ever-increasing number of North American pulp and paper mills. Because of the possibility of a tube failure, this is a significant safety issue, and, because of the extra time required for tube inspection and repair, this can become an economic issue as well. In a project funded by the U.S. Department of Energy and given wide support among paper companies, boiler manufacturers, and tube fabricators, studies are being conducted to determine the cause of the cracking and to identify alternate materials and/or operating procedures to prevent tube cracking. Examination of cracked tubes has permitted characterization of crack features, and transmission electron microscopy is providing information about the thermal history, particularly cyclic thermal exposures, that tubes have experienced. Neutron and x-ray diffraction techniques are being used to determine the residual stresses in as-fabricated tube panels and exposed tubes, and finite element modeling is providing information about the stresses the tubes experience during operation. Laboratory studies are being conducted to determine the susceptibility of the co-extruded 304L/SA210 tubes to stress corrosion cracking, thermal fatigue, and corrosion in molten smelt. This paper presents the current status of these studies. On the basis of all of these studies, recommendations for means to prevent tube cracking will be offered.
Date: August 1, 1997
Creator: Keiser, J.R.; Taljat, B. & Wang, X.L.
Partner: UNT Libraries Government Documents Department

Development of NDE methods for hot gas filters.

Description: Ceramic hot gas candle filters are currently under development for hot gas particulate cleanup in advanced coal-based power systems. The ceramic materials for these filters include nonoxide monolithic, nonoxide-fiber-reinforced composites, and nonoxide reticulated foam. A concern is the lack of reliable data on which to base decisions for reusing or replacing hot gas filters during plant shutdowns. The work in this project is aimed at developing nondestructive evaluation (FIDE) technology to allow detection, and determination of extent, of life-limiting characteristics such as thermal fatigue, oxidation, damage from ash bridging such as localized cracking, damage from local burning, and elongation at elevated temperature. Although in-situ NDE methods are desirable in order to avoid disassembly of the candle filter vessels, the current vessel designs, the presence of filter cakes and possible ash bridging, and the state of NDE technology prevent this. Candle filter producers use a variety of NDE methods to ensure as-produced quality. While impact acoustic resonance offers initial promise for examining new as-produced filters and for detecting damage in some monolithic filters when removed from service, it presents difficulties in data interpretation, it lacks localization capability, and its applicability to composites has yet to be demonstrated. Additional NDE technologies being developed and evaluated in this program and whose applicability to both monolithics and composites has been demonstrated include (a) full-scale thermal imaging for analyzing thermal property variations; (b) fret, high-spatial-resolution X-ray imaging for detecting density variations and dimensional changes; (c) air-coupled ultrasonic methods for determining through-thickness compositional variations; and (d) acoustic emission technology with mechanical loading for detecting localized bulk damage. New and exposed clay-bonded SiC filters and CVI-SiC composite filters have been tested with these additional NDE methods.
Date: July 21, 1999
Creator: Deemer, C.; Ellingson, W. A.; Koehl, E. R.; Lee, H.; Spohnholtz, T. & Sun, J. G.
Partner: UNT Libraries Government Documents Department

Laser Pulse Heating

Description: Recently, interest has developed in pulsed heating effects on a copper surface [1]. Pulsed heating is one of the limits on the gradient of a structure based linac. The heat generated by an intense rf pulse on the metal surface can result in hundreds of degrees of temperature rise at 1 GeV/m. After a certain number of cycles, the metal may crack due to thermal fatigue and the surface properties may deteriorate. In this article, we describe an experiment to use a high power laser to study the pulsed temperature rise on a metal surface.
Date: April 12, 1999
Creator: Lin, Xintian (Eddie)
Partner: UNT Libraries Government Documents Department

Damage evolution in metal matrix composites subjected to thermomechanical fatigue

Description: A thermomechanical analysis of unidirectional continuous fiber metal matrix composites is presented. The analysis includes the effects of processing induced residual thermal stresses, interface cracking, and inelastic matrix behavior on damage evolution. Due to the complexity of the nonlinear effects, the analysis is performed computationally using the finite element method. The interface fracture is modeled by a nonlinear constitutive model. The problem formulation is summarized and results are presented for a four-ply unidirectional SCS-6/{beta}21S titanium composite under high temperature isothermal mechanical fatigue.
Date: May 1, 1995
Creator: Allen, D.H.; Hurtado, L.D. & Helms, K.L.E.
Partner: UNT Libraries Government Documents Department

The effect of microstructure on the thermal fatigue resistance of investment cast and wrought AISI H13 hot work die steel

Description: Variable thickness plate investment castings of AISI H13 hot work die steel were pour and characterized in the as-cast and heat treated conditions. The characterization included light microscopy and mechanical testing. Wrought samples of standard and premium grade H13 steel were heat treated and characterized similarly for comparison. Microstructural differences were observed in as-cast samples poured to different section thicknesses. Dendrite cell size and carbide morphology constituted the most prominent microstructural differences observed. After a full heat treatment, however, Microstructural differences between the wrought material and cast materials were slight regardless of section thickness. The mechanical properties of the cast and heat treated material proved similar to the properties of the standard heat treated wrought material. A thermal fatigue testing unit was designed and built to correlate the heat checking susceptibility of AISI H13 steel to its processing and consequent microstructural condition. Surface hardness decreased significantly with thermal cycling, and heat checking was noticed in as few as 50 cycles. Thermal softening and thermal fatigue susceptibility were quantified and discussed relative to the microstructural conditions created by processing and heat treatment. It was found that the premium grade wrought H13 steel provided the best overall resistance to heat checking; however, the heat-treat cast and as-cast H13 tool steel (made from standard grade wrought H13 tool steel) provided comparable resistance to heat checking in terms Of area fraction of heat checking and maximum crack length.
Date: July 1, 1995
Creator: Hochanadel, P.W.; Edwards, G.R.; Maguire, M.C. & Baldwin, M.D.
Partner: UNT Libraries Government Documents Department

Nitride-bonded silicon carbide composite filter

Description: The objective of this program is to develop and demonstrate an advanced hot gas filter, using ceramic component technology, with enhanced durability to provide increased resistance to thermal fatigue and crack propagation. The material is silicon carbide fiber reinforced nitride bonded silicon carbide.
Date: December 1, 1995
Creator: Thomson, B.N. & DiPietro, S.G.
Partner: UNT Libraries Government Documents Department

High heat flux testing capabilities at Sandia National Laboratories - New Mexico

Description: High heat flux testing for the United States fusion power program is the primary mission of the Plasma Materials Test Facility (PMTF) located at Sandia National Laboratories - New Mexico. This facility, which is owned by the United States Department of Energy, has been in operation for over 17 years and has provided much of the high heat flux data used in the design and evaluation of plasma facing components for many of the world`s magnetic fusion, tokamak experiments. In addition to domestic tokamaks such as Tokamak Fusion Test Reactor (TFTR) at Princeton and the DIII-D tokamak at General Atomics, components for international experiments like TEXTOR, Tore-Supra, and JET also have been tested at the PMTF. High heat flux testing spans a wide spectrum including thermal shock tests on passively cooled materials, thermal response and thermal fatigue tests on actively cooled components, critical heat flux-burnout tests, braze reliability tests and safety related tests. The objective of this article is to provide a brief overview of the high heat flux testing capabilities at the PMTF and describe a few of the experiments performed over the last year.
Date: December 31, 1994
Creator: Youchison, D.L.; McDonald, J.M. & Wold, L.S.
Partner: UNT Libraries Government Documents Department

THERMAL FATIGUE--AN ANALYSIS OF THE EXPERIMENTAL METHOD

Description: An analysis of the conventional (Coffin-type) thermalfatigue test is presented by describing an analytical model from which three methods for determinlng the plasticstrain range are derived. One of the methods for calculating the plastic strain does not require the knowledge or use of the thermal coefficient, modulus of elasticity, or stress range. The accuracy of this method is not affected by the varintion of the thermal coefficient, modulus of elasticity, or yield strength during the heating and cooling periods. Plastic strains resulting from yielding and relaxation may be accounted for by this method. The errors of conventional methods are discussed. A method for plotting the stress-strain hysteresis loop is also given. From an analysis of the load- temperature loop, it is clearly shown how all of the signlficant variables can be determined without plotting a stress-strain hysteresis loop. The plastic-strain range, the mechanical-strain range (elastic plus plastic), the stress range, and the plastic-strain energy per cycle can easily be determined from the load- temperature loop. An alternate test is suggested that minimizes all of the major difficulties of the conventional test. An improved test specimen for the conventional test is also recommended. (auth)
Date: January 1, 1963
Creator: Carden, A.E.
Partner: UNT Libraries Government Documents Department

Modeling Thermal Fatigue in CPV Cell Assemblies: Preprint

Description: A finite element model has been created to quantify the thermal fatigue damage of the CPV die attach. Simulations are used to compare to results of empirical thermal fatigue equations originally developed for accelerated chamber cycling. While the empirical equations show promise when extrapolated to the lower temperature cycles characteristic of weather-induced temperature changes in the CPV die attach, it is demonstrated that their damage does not accumulate linearly: the damage a particular cycle contributes depends on the preceding cycles. Simulations of modeled CPV cell temperature histories provided for direct comparison of the FEM and empirical methods, and for calculation of equivalent times provided by standard accelerated test sequences.
Date: July 1, 2011
Creator: Bosco, N.; Silverman, T. J. & Kurtz, S.
Partner: UNT Libraries Government Documents Department