Download or read book Towards the Development of a Physics Based Thermo Mechanical Fatigue Life Prediction Model for a Single Crystalline Ni Base Superalloy written by Robert Amaro and published by . This book was released on 2014 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: A long term effort has been underway to develop a mechanism-based model for life prediction under thermo-mechanical fatigue (TMF) cycling. A model has been developed which is based upon the impingement of slip bands upon oxidized regions and subsequent initiation of a crack due to stress concentration. The concept of an effective cycle temperature, Teff, and the dynamic nature of the material are critical components of the model and result in the ability to produce very accurate life predictions. It has also been shown that the model is capable of addressing complexities such as imposed high cycle fatigue (HCF) while still producing excellent agreement with the experiment. However, given the fact that this material is used for jet engine turbine blades and that such blades have cooling holes which act as notches, the next step in the development of this model is to incorporate it into a notched environment. The principal features of the TMF model are reviewed and a strategy for full integration into notched fatigue life prediction is discussed. Recent experimental results are presented which are based upon simulating smooth bar conditions at the notch root and a first approach to numerical simulation (called Q fit) is presented. Suggestions for further research are discussed.
Download or read book Superalloys 2012 written by Eric S. Huron and published by John Wiley & Sons. This book was released on 2012-10-02 with total page 952 pages. Available in PDF, EPUB and Kindle. Book excerpt: A superalloy, or high-performance alloy, is an alloy that exhibits excellent mechanical strength at high temperatures. Superalloy development has been driven primarily by the aerospace and power industries. This compilation of papers from the Twelfth International Symposium on Superalloys, held from September 9-13, 2012, offers the most recent technical information on this class of materials.
Download or read book Thermomechanical Fatigue Crack Formation in a Single Crystal Ni base Superalloy written by Robert L. Amaro and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This research establishes a physics-based life determination model for the second generation single crystal superalloy PWA 1484 experiencing out-of-phase thermomechanical fatigue (TMF). The life model was developed as a result of a combination of critical mechanical tests, dominant damage characterization and utilization of well-established literature. The resulting life model improves life prediction over currently employed methods and provides for extrapolation into yet unutilized operating regimes. Particularly, the proposed deformation model accounts for the materials' coupled fatigue-environment-microstructure response to TMF loading. Because the proposed model is be based upon the underlying deformation physics, the model is robust enough to be easily modified for other single crystal superalloys having similar microstructure. Future use of this model for turbine life estimation calculations would be based upon the actual deformation experienced by the turbine blade, thereby enabling turbine maintenance scheduling based upon on a "retirement for a cause" life management scheme rather than the currently employed "safe-life" calculations. This advancement has the ability to greatly reduce maintenance costs to the turbine end-user since turbine blades would be removed from service for practical and justifiable reasons. Additionally this work will enable a rethinking of the warranty period, thereby decreasing warranty related replacements. Finally, this research provides a more thorough understanding of the deformation mechanisms present in loading situations that combine fatigue-environment-microstructure effects.
Download or read book Nickel Base Single Crystals Across Length Scales written by Loeïz Nazé and published by Elsevier. This book was released on 2021-09-28 with total page 612 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nickel Base Single Crystals Across Length Scales is addresses the most advanced knowledge in metallurgy and computational mechanics and how they are applied to superalloys used as bare materials or with a thermal barrier coating system. Joining both aspects, the book helps readers understand the mechanisms driving properties and their evolution from fundamental to application level. These guidelines are helpful for students and researchers who wish to understand issues and solutions, optimize materials, and model them in a cross-check analysis, from the atomistic to component scale. The book is useful for students and engineers as it explores processing, characterization and design. - Provides an up-to-date overview on the field of superalloys - Covers the relationship between microstructural evolution and mechanical behavior at high temperatures - Discusses both basic and advanced modeling and characterization techniques - Includes case studies that illustrate the application of techniques presented in the book
Download or read book Fatigue Life Prediction Under Thermal Mechanical Loading in a Nickel Base Superalloy written by H. Bernard and published by . This book was released on 1993 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermal-mechanical fatigue of IN-100, a cast nickel base superalloy, was previously shown to involve mainly early crack growth using either bare or aluminized specimens. This crack growth was found to be controlled by interdendritic oxidation. A model for engineering life to crack initiation is thus proposed to describe this microcrack growth phase using local stresses in a microstructural volume element at the crack tip. The identification of damage equations involves fatigue crack growth data on compact tension (CT) specimens, interdendritic oxidation kinetics measurements and fatigue crack growth on CT specimens that have been embrittled by previous oxidation at high temperature. The application of this model to life prediction is shown for low cycle fatigue and thermal-mechanical fatigue specimens of bare and coated specimens as well as for thermal shock experiments.
Download or read book Application of an Energy Based Life Prediction Model to Bithermal and Thermomechanical Fatigue written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-17 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The inelastic hysteresis energy applied to the material in a cycle is used as the basis for predicting nonisothermal fatigue life of a wrought cobalt-base superalloy, Haynes 188, from isothermal fatigue data. Damage functions that account for hold-time effects and time-dependent environmental phenomena such as oxidation and hot corrosion are proposed in terms of the inelastic hysteresis energy per cycle. The proposed damage functions are used to predict the bithermal and thermomechanical fatigue lives of Haynes 188 between 316 and 760 C from isothermal fatigue data. Predicted fatigue lives of all but two of the nonisothermal tests are within a factor of 1.5 of the experimentally observed lives. Radhakrishnan, V. M. and Kalluri, Sreeramesh and Halford, Gary R. Glenn Research Center NASA-TM-106684, E-9038, NAS 1.15:106684 NAS3-27186; RTOP 505-63-5B...
Download or read book Application of an Energy based Life Prediction Model to Bithermal and Thermomechanical Fatigue written by V. M. Radhakrishnan and published by . This book was released on 1994 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Thermomechanical Fatigue Behaviour of Coated and Bare Nickel Based Superalloy Single Crystals written by E. Chataigner and published by . This book was released on 1996 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Constitutive Modeling and Life Prediction in Ni base Superalloys written by Mahesh M. Shenoy and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Microstructural features at different scales affect the constitutive stress-strain response and the fatigue crack initiation life in Ni-base superalloys. While numerous efforts have been made in the past to experimentally characterize the effects of these features on the stress-strain response and/or the crack initiation life, there is a significant variability in the data with sometimes contradictory conclusions, in addition to the substantial costs involved in experimental testing. Computational techniques can be useful tools to better understand these effects since they are relatively inexpensive and are not restricted by the limitations in processing techniques. The effect of microstructure on the stress-strain response and the variability in fatigue life were analyzed using two Ni-base superalloys; DS GTD111 which is a directionally solidified Ni-base superalloy, and IN100 which is a polycrystalline Ni-base superalloy. Physically-based constitutive models were formulated and implemented as user material subroutines in ABAQUS using the single crystal plasticity framework which can predict the material stress-strain response with the microstructure-dependence embedded into them. The model parameters were calibrated using experimental cyclic stress-strain histories. A computational exercise was employed to quantify the influence of idealized microstructural variables on the fatigue crack initiation life. Understanding was sought regarding the most significant microstructure features using explicit modeling of the microstructure with the aim to predict the variability in fatigue crack initiation life and to guide material design for fatigue resistant microstructures. Lastly, it is noted that crystal plasticity models are often too computationally intensive if the objective is to model the macroscopic behavior of a textured or randomly oriented 3-D polycrystal in an engineering component. Homogenized constitutive models were formulated and implemented as user material subroutines in ABAQUS, which can capture the macroscale stress-strain response in both DS GTD111 and IN100. Even though the study was conducted on two specific Ni-base superalloys; DS GTD111 and IN100, the objective was to develop generic frameworks which should also be applicable to other alloy systems.
Download or read book A Life Prediction Model for Thermomechanical Fatigue Based on Microcrack Propagation written by SD. Antolovich and published by . This book was released on 1993 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: A thermomechanical fatigue (TMF) life prediction model is developed based on the concept of microcrack propagation. The model is used to correlate high temperature fatigue lives of two nickel-base superalloys.
Download or read book Collaborative Research on Thermo Mechanical and Isothermal Low Cycle Fatigue Strength of Ni Base Superalloys and Protective Coatings at Elevated Temperatures in The Society of Materials Science Japan JSMS written by Y. Yamazaki and published by . This book was released on 2003 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: Results of collaborative research by "Subcommittee on Superalloys and Coatings" in The Society of Materials Science, Japan (JSMS), are presented, which cover the thermo-mechanical fatigue (TMF) and high temperature isothermal low-cycle fatigue (ILCF) strengths of Ni-Base superalloy, substrate alloys and the protective coatings. Three kinds of Ni-base superalloys were selected as the substrate: a single crystal alloy, CMSX-4; a directionally solidified alloy, CM247LC; and a polycrystalline alloy, IN738LC. On these substrate specimens the CoNiCrAlY alloy was coated by 250 ?m in thickness by low pressure plasma spraying, and then aluminized. This process was managed and undertaken by one of member companies of the Subcommittee. The round robin TMF and ILCF tests were carried out under a strain ratio of -1 at temperature ranged between 400 and 900°C. In the former the tests were performed under the out-of-phase and diamond phase conditions in which the phase difference between strain and temperature were 180° and 90°, respectively. It is shown by the round-robin tests that the TMF lives, as well as the ILCF, were strongly dependent on the substrate alloys. Many important, or noteworthy results were also found: e.g., the TMF fracture behavior of the coated specimens revealed some unique characteristics that were hardly deduced from that of the bare specimens. The effect of coating on the ILCF life was strongly dependent on the temperature. It was not reasonable, or difficult to try to estimate the TMF life of the coatings from the ILCF test results. Based on the observations on the crack initiation, propagation and the fracture surface, the effects of the substrate alloy and the coating on the TMF and ILCF lives were discussed.
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 1044 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Bithermal Fatigue of a Nickel Base Superalloy Single Crystal written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-16 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: The thermomechanical fatigue behavior of a nickel-base superalloy single crystal was investigated using a bithermal test technique. The bithermal fatigue test was used as a simple alternative to the more complex thermomechanical fatigue test. Both in-phase and out-of-phase bithermal tests were performed on (100)-oriented coated and bare Rene N4 single crystals. In out-of-plane bithermal tests, the tensile and compressive halves of the cycle were applied isothermally at 760 and 982 C, respectively, while for the in-phase bithermal tests the temperature-loading sequence was reversed. The bithermal fatigue lives of bare specimens were shorter than the isothermal fatigue lives at either temperature extreme when compared on an inelastic strain basis. Both in-phase and out-of-phase bithermal fatigue life curves converged in the large strain regime and diverged in the small strain regime, out-of-phase resulting in the shortest lives. The coating had no effect on life for specimens cycled in-phase; however, the coating was detrimental for isothermal fatigue at 760 C and for out-of-phase fatigue under large strains. Verrilli, Michael J. Glenn Research Center NASA-TM-100885, E-4118, NAS 1.15:100885 ...
Download or read book Enhancement of Thermomechanical Fatigue Resistance of a Monocrystalline Nickel base Superalloy by Pre rafting written by U. Tetzlaff and published by . This book was released on 2003 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: In ?'-hardened monocrystalline nickel-base superalloys having a negative ?/?' lattice misfit, the prior introduction of so-called ?/?' rafts aligned parallel to the stress axis (by a small creep pre-deformation in compression) has been shown to enhance both the high-temperature isothermal fatigue strength and the tensile creep resistance. It was hence of interest to perform a systematic study of the thermo-mechanical fatigue (TMF) behavior of specimens of a monocrystalline nickel-base superalloy with the main aim to test whether an initial ?/?' raft microstructure can also enhance the TMF resistance. The experiments were performed on [001]-orientated monocrystalline specimens of the superalloy SRR 99 which contained either the initial ?/?'-microstructure with cuboidal ?' precipitates or a ?/?' raft microstructure aligned roughly parallel to the stress axis. The latter was introduced by a small compressive creep deformation of less than 0.4% at a temperature of 1050°C and a stress of 120 MPa. Different strain-controlled TMF cycle forms were employed. However, in most tests a counter-clockwise-diamond (CCD) cycle (temperature interval ?T = 600°C-1100°C) was used with a total strain rate of 6.67•10-5 s-1. This CCD cycle is considered to be close to service conditions. The mechanical strain range ??m was varied in the range of ??mech = 1%, leading to fatigue lives in the order of some 1000 cycles. It could be shown that pre-rafting in compression enhances the TMF fatigue life significantly for all cases of CCD-cycles investigated.
Download or read book Thermomechanical Fatigue Behavior of Materials written by Michael A. McGaw and published by ASTM International. This book was released on 2003 with total page 330 pages. Available in PDF, EPUB and Kindle. Book excerpt: "ASTM Stock Number: STP1428. - "Fourth Symposium on Thermomechanical Fatigue Behavior of Materials, held in Dallas, Texas on November 7-8, 2001. The Symposium was sponsored by ASTM Committee E08 on Fatigue and Fracture and its Subcommittee E08.05 on Cyclic Deformation and Fat. - Includes bibliographical references and indexes. ASTM International; 2011.
Download or read book Thermo mechanical Fatigue Investigation of Single Crystal Nickel Base Superalloy SRR99 written by F. Rézaï-Aria and published by . This book was released on 2000 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper deals with the comparison between thermal fatigue (TF) and thermomechanical fatigue (TMF) testing for SRR99 superalloy. First, a measured TF mechanical strain-temperature (?m-T) profile between 200°C and 1100°C has been reproduced on a TMF specimen to allow for an estimation of the stresses and inelastic strains which occur during TF. Thermal-fatigue-based (TFB) ?m-T profiles were determined based on the measured TF profiles. These TFB cycles, together with the well-known out-of-phase profile, were employed for all of TMF tests. The comparison of the results reveals that the TF and TMF out-phase tests are more damaging in terms both of the applied stress and strain range, while the TMF out-of-phase test is more severe if the comparison is made in terms of the inelastic strain range. Finally, it is shown that the results can be rationalized quite well by plotting the fatigue lives as a function of the maximum stabilized stress (?max).
