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High Temperature Fatigue And Fatigue Creep Responses Of Alloy 617 Experimental And Unified Constitutive Modeling
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Book Synopsis High Temperature Fatigue and Fatigue-Creep Responses of Alloy 617 - Experimental and Unified Constitutive Modeling by : Patrick Graham Pritchard
Download or read book High Temperature Fatigue and Fatigue-Creep Responses of Alloy 617 - Experimental and Unified Constitutive Modeling written by Patrick Graham Pritchard and published by . This book was released on 2014 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Constitutive Modeling of High Temperature Uniaxial Creep-Fatigue and Creep-Ratcheting Responses of Alloy 617 by :
Download or read book Constitutive Modeling of High Temperature Uniaxial Creep-Fatigue and Creep-Ratcheting Responses of Alloy 617 written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Inconel Alloy 617 is a high temperature creep and corrosion resistant alloy and is a leading candidate for use in Intermediate Heat Exchangers (IHX) of the Next Generation Nuclear Plants (NGNP). The IHX of the NGNP is expected to experience operating temperatures in the range of 800 degrees - 950 degrees C, which is in the creep regime of Alloy 617. A broad set of uniaxial, low-cycle fatigue, fatigue-creep, ratcheting, and ratcheting-creep experiments are conducted in order to study the fatigue and ratcheting responses, and their interactions with the creep response at high temperatures. A unified constitutive model developed at North Carolina State University is used to simulate these experimental responses. The model is developed based on the Chaboche viscoplastic model framework. It includes cyclic hardening/softening, strain rate dependence, strain range dependence, static and dynamic recovery modeling features. For simulation of the alloy 617 responses, new techniques of model parameter determination are developed for optimized simulations. This paper compares the experimental responses and model simulations for demonstrating the strengths and shortcomings of the model.
Book Synopsis Creep-fatigue Damage Investigation and Modeling of Alloy 617 at High Temperatures by : Fraaz Tahir
Download or read book Creep-fatigue Damage Investigation and Modeling of Alloy 617 at High Temperatures written by Fraaz Tahir and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Very High Temperature Reactor (VHTR) is one of six conceptual designs proposed for Generation IV nuclear reactors. Alloy 617, a solid solution strengthened Ni-base superalloy, is currently the primary candidate material for the tubing of the Intermediate Heat Exchanger (IHX) in the VHTR design. Steady-state operation of the nuclear power plant at elevated temperatures leads to creep deformation, whereas loading transients including startup and shutdown generate fatigue. A detailed understanding of the creep-fatigue interaction in Alloy 617 is necessary before it can be considered as a material for nuclear construction in ASME Boiler and Pressure Vessel Code. Current design codes for components undergoing creep-fatigue interaction at elevated temperatures require creep-fatigue testing data covering the entire range from fatigue-dominant to creep-dominant loading. Classical strain-controlled tests, which produce stress relaxation during the hold period, show a saturation in cycle life with increasing hold periods due to the rapid stress-relaxation of Alloy 617 at high temperatures. Therefore, applying longer hold time in these tests cannot generate creep-dominated failure. In this study, uniaxial isothermal creep-fatigue tests with non-traditional loading waveforms were designed and performed at 850 and 950°C, with an objective of generating test data in the creep-dominant regime. The new loading waveforms are hybrid strain-controlled and force-controlled testing which avoid stress relaxation during the creep hold. The experimental data showed varying proportions of creep and fatigue damage, and provided evidence for the inadequacy of the widely-used time fraction rule for estimating creep damage under creep-fatigue conditions. Micro-scale damage features in failed test specimens, such as fatigue cracks and creep voids, were quantified using a Scanning Electron Microscope (SEM) to find a correlation between creep and fatigue damage. Quantitative statistical imaging analysis showed that the microstructural damage features (cracks and voids) are correlated with a new mechanical driving force parameter. The results from this image-based damage analysis were used to develop a phenomenological life-prediction methodology called the effective time fraction approach. Finally, the constitutive creep-fatigue response of the material at 950°C was modeled using a unified viscoplastic model coupled with a damage accumulation model. The simulation results were used to validate an energy-based constitutive life-prediction model, as a mechanistic model for potential component and structure level creep-fatigue analysis.
Book Synopsis Unified Constitutive Modeling for High Temperature Fatigue-Creep and Creep Responses of Haynes 230 by : Paul Ryan Barrett
Download or read book Unified Constitutive Modeling for High Temperature Fatigue-Creep and Creep Responses of Haynes 230 written by Paul Ryan Barrett and published by . This book was released on 2015 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Multiaxial Creep-Fatigue and Creep- Ratcheting Failures of Grade 91 and Haynes 230 Alloys Toward Addressing Design Issues of Gen IV Nuclear Power Plants by :
Download or read book Multiaxial Creep-Fatigue and Creep- Ratcheting Failures of Grade 91 and Haynes 230 Alloys Toward Addressing Design Issues of Gen IV Nuclear Power Plants written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The proposed research will develop systematic sets of uniaxial and multiaxial experimental data at a very high temperature (850-950oC) for Alloy 617. The loading histories to be prescribed in the experiments will induce creep-fatigue and creep-ratcheting failure mechanisms. These experimental responses will be scrutinized in order to quantify the influences of temperature and creep on fatigue and ratcheting failures. A unified constitutive model (UCM) will be developed and validated against these experimental responses. The improved UCM will be incorporated into the widely used finite element commercial software packages ANSYS. The modified ANSYS will be validated so that it can be used for evaluating the very high temperature ASME- NH design-by-analysis methodology for Alloy 617 and thereby addressing the ASME-NH design code issues.
Book Synopsis Challenges In Mechanics of Time-Dependent Materials and Processes in Conventional and Multifunctional Materials, Volume 2 by : Bonnie Antoun
Download or read book Challenges In Mechanics of Time-Dependent Materials and Processes in Conventional and Multifunctional Materials, Volume 2 written by Bonnie Antoun and published by Springer Science & Business Media. This book was released on 2013-08-28 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: Challenges in Mechanics of Time-Dependent Materials and Processes in Conventional and Multifunctional Materials, Volume 2: Proceedings of the 2013 SEM Annual Conference& Exposition on Experimental and Applied Mechanics, the second volume of eight from the Conference, brings together contributions to this important area of research and engineering. The collection presents early findings and case studies on fundamental and applied aspects of Experimental Mechanics, including papers in the following general technical research areas: Metallic, Polymeric and Composite Materials Effects of Extreme Environments including Radiation Resistance, Damage, and Aging Challenges in Time-dependent Behavior Modeling of Low, Moderate and High Strain Rates Effects of Frequency and Hysteretic Heating Effects of Inhomogeneities on the Time-Dependent Behavior Composite, Hybrid and Multifunctional Materials Challenges in Time-dependent Behavior Modeling Viscoelastoplasticity and Damage Effects of Interfaces and Interphases on the Time-Dependent Behavior Environmental and Reactive Property Change Effects on Thermomechanical and Multifunctional Behaviors Modeling and Characterization of Fabrication Processes of Conventional and Multifunctional Materials Time-dependent and Small-scale Effects in Micro/Nano-scale Testing Time-dependent Processes in Biomaterials
Book Synopsis Prediction of the Creep-Fatigue Lifetime of Alloy 617 by :
Download or read book Prediction of the Creep-Fatigue Lifetime of Alloy 617 written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A relatively simple method using the nominal constant average stress information and the creep rupture model is developed to predict the creep-fatigue lifetime of Alloy 617, in terms of time to rupture. The nominal constant average stress is computed using the stress relaxation curve. The predicted time to rupture can be converted to number of cycles to failure using the strain range, the strain rate during each cycle, and the hold time information. The predicted creep-fatigue lifetime is validated against the experimental measurements of the creep-fatigue lifetime collected using conventional laboratory creep-fatigue tests. High temperature creep-fatigue tests of Alloy 617 were conducted in air at 950°C with a tensile hold period of up to 1800s in a cycle at total strain ranges of 0.3% and 0.6%. It was observed that the proposed method is conservative in that the predicted lifetime is less than the experimentally determined values. The approach would be relevant to calculate the remaining useful life to a component like a steam generator that might fail by the creep-fatigue mechanism.
Book Synopsis Creep and Creep-Fatigue of Alloy 617 Weldments by :
Download or read book Creep and Creep-Fatigue of Alloy 617 Weldments written by and published by . This book was released on 2014 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: Alloy 617 is the primary candidate material for the heat exchanger of a very high temperature gas cooled reactor intended to operate up to 950°C. While this alloy is currently qualified in the ASME Boiler and Pressure Vessel Code for non-nuclear construction, it is not currently allowed for use in nuclear designs. A draft Code Case to qualify Alloy 617 for nuclear pressure boundary applications was submitted in 1992, but was withdrawn prior to approval. Prior to withdrawal of the draft, comments were received indicating that there was insufficient knowledge of the creep and creep-fatigue behavior of Alloy 617 welds. In this report the results of recent experiments and analysis of the creep-rupture behavior of Alloy 617 welds prepared using the gas tungsten arc process with Alloy 617 filler wire. Low cycle fatigue and creep-fatigue properties of weldments are also discussed. The experiments cover a range of temperatures from 750 to 1000°C to support development of a new Code Case to qualify the material for elevated temperature nuclear design. Properties of the welded material are compared to results of extensive characterization of solution annealed plate base metal.
Book Synopsis Thermomechanical Fatigue of Mar-M247 by : Kyle A. Brindley
Download or read book Thermomechanical Fatigue of Mar-M247 written by Kyle A. Brindley and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this work is to establish a life prediction methodology for thermomechanical loading of the Ni-base superalloy Mar-M247 over a larger temperature range than previous work. The work presented in this thesis extends the predictive capability of the Sehitoglu-Boismier unified thermo-viscoplasticity constitutive model and thermomechanical life model from a maximum temperature of 871C to a maximum temperature of 1038C. The constitutive model, which is suitable for predicting stress-strain history under thermomechanical loading, is adapted and calibrated using the response from isothermal cyclic experiments conducted at temperatures from 500C to 1038C at different strain rates with and without dwells. In the constitutive model, the flow rule function and parameters as well as the temperature dependence of the evolution equation for kinematic hardening are established. In the elevated temperature regime, creep and stress relaxation are critical behaviors captured by the constitutive model. The life model accounts for fatigue, creep, and environmental-fatigue damage under both isothermal and thermomechanical fatigue. At elevated temperatures, the damage terms must be calibrated to account for thermally activated damage mechanisms which change with increasing temperature. At lower temperatures and higher strain rates, fatigue damage dominates life prediction, while at higher temperatures and slower strain rates, environmental-fatigue and creep damage dominate life prediction. Under thermomechanical loading, both environmental-fatigue and creep damage depend strongly on the relative phasing of the thermal and mechanical strain rates, with environmental-fatigue damage dominating during out-of-phase thermomechanical loading and creep damage dominating in-phase thermomechanical loading. The coarse-grained polycrystalline microstructure of the alloy studied causes a significant variation in the elastic response, which can be linked to the crystallographic orientation of the large grains. This variation in the elastic response presents difficulties for both the constitutive and life models, which depend upon the assumption of an isotropic material. The extreme effects of a large grained microstructure on the life predictions is demonstrated, and a suitable modeling framework is proposed to account for these effects in future work.
Book Synopsis Report on FY15 Alloy 617 SMT Creep-Fatigue Test Results by :
Download or read book Report on FY15 Alloy 617 SMT Creep-Fatigue Test Results written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: For the temperature range of 990-950C, Alloy 617 is a candidate IHX structural material for high temperature gas reactors (HTGRs) because of its high temperature creep properties. Also, its superior strength over a broad temperature range also offers advantages for certain component applications. In order for the designers to be able to use Alloy 617 for these high temperature components, Alloy 617 has to be approved for use in Section III (the nuclear section) of the ASME (American Society of Mechanical Engineers) Boiler and Pressure Vessel Code. A plan has been developed to propose a Code Case for use of Alloy 617 at elevated temperature in Section III of the ASME Code by September 2015. There has not been a new high temperature material approved for use in Section III for almost 20 years. The Alloy 617 Code Case effort would lead the way to establish a path for Code qualification of new high temperature materials of interest to other advanced SMRs. Creep-fatigue at elevated temperatures is the most damaging structural failure mode. In the past 40 years significant efforts have been devoted to the elevated temperature Code rule development in Section III, Subsection NH* of the ASME Boiler and Pressure Vessel Code, to ascertain conservative structural designs to prevent creep-fatigue failure. The current Subsection NH creep-fatigue procedure was established by the steps of (1) analytically obtaining a detailed stress-strain history, (2) comparing the stress and strain components to cyclic test results deconstructed into stress and strain quantities, and (3) recombining the results to obtain a damage function in the form of the so-called creep-fatigue damage-diagram. The deconstruction and recombination present difficulties in evaluation of test data and determination of cyclic damage in design. The uncertainties in these steps lead to the use of overly conservative design factors in the current creep-fatigue procedure. In addition, and of major significance to the viability of the Alloy 617 Code Case, the use of the current elastic analysis based rules in Subsection NH for the evaluation of strain limits (a precursor for the creep-fatigue rules) and the creep-fatigue rules themselves have been deemed inappropriate for Alloy 617 at temperatures above 650C (Corum and Brass, 1991). The rationale for this exclusion is that at higher temperatures it is not feasible to decouple plasticity and creep, which is the basis for the current simplified rules. This temperature, 650C, is well below the temperature range of interest for this material for the High Temperature Gas Cooled Reactor (HTGR) as well as the VHTR. The only current alternative is, thus, a full inelastic analysis which requires sophisticated material models which have not yet been formulated and verified. To address the prohibition on the use of current methods at very high temperatures, proposed Code rules have been developed which are based on the use of elastic-perfectly plastic (E-PP) analysis methods and which are expected to be applicable to very high temperatures. To provide data to implement the proposed rules and to verify their application, a series of tests have been initiated. One test concept, the Simplified Model Test (SMT), takes into account the stress and strain redistribution in real structures by including representative follow-up characteristics in the test specimen. The correlation parameter between test and design is the elastically calculated strain, and the dependent test variable is the observed cycles to failure. Although the initial priority for the SMT approach is to generate data to support validation of the E-PP Code Case for evaluation of creep-fatigue damage, the broader goal of the SMT approach is to develop a methodology for evaluation of creep fatigue damage which is simpler to implement than the current complex rules and applicable to the full temperature range from ambient conditions to the very high temperature creep regime of 900 ...
Download or read book Metals Abstracts written by and published by . This book was released on 1993 with total page 1234 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Creep-Fatigue Behavior of Alloy 617 at 850 and 950°C, Revision 2 by :
Download or read book Creep-Fatigue Behavior of Alloy 617 at 850 and 950°C, Revision 2 written by and published by . This book was released on 2015 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt: Alloy 617 is the leading candidate material for an Intermediate Heat Exchanger (IHX) of the Very High Temperature Reactor (VHTR). To evaluate the behavior of this material in the expected service conditions, strain-controlled cyclic tests including hold times up to 9000 s at maximum tensile strain were conducted at 850 and 950 degrees C. At both temperatures, the fatigue resistance decreased when a hold time was added at peak tensile strain. The magnitude of this effect depended on the specific mechanisms and whether they resulted in a change in fracture mode from transgranular in pure fatigue to intergranular in creep-fatigue for a particular temperature and strain range combination. Increases in the tensile hold duration beyond an initial value were not detrimental to the creep-fatigue resistance at 950 degrees C but did continue to degrade the lifetimes at 850 degrees C.
Book Synopsis Constitutive Modeling for Very High Temperature Thermo-Mechanical Fatigue Responses by : Raasheduddin Ahmed
Download or read book Constitutive Modeling for Very High Temperature Thermo-Mechanical Fatigue Responses written by Raasheduddin Ahmed and published by . This book was released on 2013 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Fatigue at Elevated Temperatures by : A. E. Carden
Download or read book Fatigue at Elevated Temperatures written by A. E. Carden and published by . This book was released on 1973 with total page 822 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1983 with total page 1368 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Creep and Environmental Effects on the High Temperature Creep-Fatigue Behavior of Alloy 617 by : L. J. Carroll
Download or read book Creep and Environmental Effects on the High Temperature Creep-Fatigue Behavior of Alloy 617 written by L. J. Carroll and published by . This book was released on 2011 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Alloy 617 is the leading candidate material for an intermediate heat exchanger (IHX) of the very high temperature reactor (VHTR), expected to have an outlet temperature as high as 950°C. Acceptance of Alloy 617 in Section III of the ASME Code for nuclear construction requires a detailed understanding of the creep-fatigue behavior. Strain-controlled low cycle fatigue (LCF) tests including hold times up to 1800 s at maximum tensile strain were conducted at 950°C and a total strain range of 0.3 % in air and in a simulated VHTR impure helium. For similar test conditions, the creep-fatigue behavior was globally similar in both environments. The fatigue resistance decreased when a hold time was added at peak tensile strain, consistent with the observed change in fracture mode from transgranular to intergranular. Further increases in the tensile hold time, beyond 180 s, were not detrimental to the creep-fatigue resistance. The influence of oxidation on the fatigue crack initiation and propagation is discussed. Bulk damage in the form of grain boundary cracking was present in the interior of the creep-fatigue specimens. This bulk cracking was quantified and found to be similar for hold times of up to 1800 s consistent with the saturation in failure lives.
Book Synopsis Progress Report on Long Hold Time Creep Fatigue of Alloy 617 at 850°C. by :
Download or read book Progress Report on Long Hold Time Creep Fatigue of Alloy 617 at 850°C. written by and published by . This book was released on 2015 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: Alloy 617 is the leading candidate material for an intermediate heat exchanger for the very high temperature reactor. To evaluate the behavior of this material in the expected service conditions, strain-controlled cyclic tests that include long hold times up to 240 minutes at maximum tensile strain were conducted at 850°C. In terms of the total number of cycles to failure, the fatigue resistance decreased when a hold time was added at peak tensile strain. Increases in the tensile hold duration degraded the creep-fatigue resistance, at least to the investigated strain controlled hold time of up to 60 minutes at the 0.3% strain range and 240 minutes at the 1.0% strain range. The creep-fatigue deformation mode is considered relative to the lack of saturation, or continually decreasing number of cycles to failure with increasing hold times. Additionally, preliminary values from the 850°C creep-fatigue data are calculated for the creep-fatigue damage diagram and have higher values of creep damage than those from tests at 950°C.
