Готові списки джерел за темами / Environment-assisted fatigue

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Добірка наукової літератури з теми "Environment-assisted fatigue"

Автор: Grafiati

Опубліковано: 11 березня 2023

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Статті в журналах з теми "Environment-assisted fatigue"

Wu, X. J., and W. Wallace. "On low-temperature environment-assisted fatigue crack propagation." Metallurgical and Materials Transactions A 25, no. 3 (March 1994): 658–59. http://dx.doi.org/10.1007/bf02651611.

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Sandviknes, J. S. S., N. D. Adasooriya, D. Pavlou, and T. Hemmingsen. "Environment-assisted fatigue of steel bridges: A conceptual framework for life assessment." IOP Conference Series: Materials Science and Engineering 1201, no. 1 (November 1, 2021): 012045. http://dx.doi.org/10.1088/1757-899x/1201/1/012045.

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Abstract This paper presents a framework based on a recently proposed fatigue strength curve of corroded steel to assess the life of an existing steel bridge exposed to environment-assisted fatigue. Environment-assisted cracking (EAC) and how it affects the structural integrity of steel bridges are introduced by the framework. Determination of both corroded and uncorroded details in a corrosive environment are also included in this framework. To conform the applicability and significance, a fatigue life of a railway bridge was assessed by methods given in the framework. The obtained fatigue lives were compared. The difference of the estimated fatigue lives emphasizes the importance of having this framework to consider the interaction of corrosion and fatigue mechanisms.

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Zelizko, V., A. Grossmuller, and M. V. Swain. "Environment Assisted Fatigue Crack Growth Behaviour of Mg-PSZ." Materials Science Forum 34-36 (January 1991): 201–5. http://dx.doi.org/10.4028/www.scientific.net/msf.34-36.201.

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Shen, R., Y. B. He, and M. Cao. "Research on the Environment Assisted Fatigue Based on Flaw Tolerance Method." Procedia Engineering 130 (2015): 1580–91. http://dx.doi.org/10.1016/j.proeng.2015.12.329.

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Gu, Kyoung Hee, Ki Sik Lee, Gum Hwa Lee, and Ki Woo Nam. "Evaluation of Fatigue Life of Ultra-High-Strength Steel under Stress Corrosion Environment." Applied Mechanics and Materials 907 (June 22, 2022): 1–7. http://dx.doi.org/10.4028/p-s303xf.

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Ultra-high-strength steel (UHSS) structures are exposed to corrosive environments during service, and hydrogen-assisted cracking (HAC) may occur owing to stress corrosion cracking and hydrogen embrittlement. In this study, the HAC threshold stress intensity factor and fatigue life of UHSS steel were evaluated by applying stress in a corrosive environment to prevent structural fracture. For specimen with semicircular slits by electric discharge machining, fatigue limit was obtained by static fatigue test under corrosive environment. The fatigue limit of the crack specimen was evaluated by the fatigue limit of the experiment and HAC threshold stress intensity factor, and comparative evaluation was performed. On the surface of cracks, grain boundaries were embrittled by corrosion, and grains were clearly observed. Meanwhile, cracks in the surface direction propagated slightly, unlike cracks in the depth direction. The static fatigue limit of UHSS (SKD11:HV670) was determined to be 400 MPa, and the fatigue limit of the crack specimen could be evaluated. The experimental results agreed well with the evaluation results.

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Bruchhausen, Matthias, Gintautas Dundulis, Alec McLennan, Sergio Arrieta, Tim Austin, Román Cicero, Walter-John Chitty, et al. "Characterization of Austenitic Stainless Steels with Regard to Environmentally Assisted Fatigue in Simulated Light Water Reactor Conditions." Metals 11, no. 2 (February 10, 2021): 307. http://dx.doi.org/10.3390/met11020307.

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A substantial amount of research effort has been applied to the field of environmentally assisted fatigue (EAF) due to the requirement to account for the EAF behaviour of metals for existing and new build nuclear power plants. We present the results of the European project INcreasing Safety in NPPs by Covering Gaps in Environmental Fatigue Assessment (INCEFA-PLUS), during which the sensitivities of strain range, environment, surface roughness, mean strain and hold times, as well as their interactions on the fatigue life of austenitic steels has been characterized. The project included a test campaign, during which more than 250 fatigue tests were performed. The tests did not reveal a significant effect of mean strain or hold time on fatigue life. An empirical model describing the fatigue life as a function of strain rate, environment and surface roughness is developed. There is evidence for statistically significant interaction effects between surface roughness and the environment, as well as between surface roughness and strain range. However, their impact on fatigue life is so small that they are not practically relevant and can in most cases be neglected. Reducing the environmental impact on fatigue life by modifying the temperature or strain rate leads to an increase of the fatigue life in agreement with predictions based on NUREG/CR-6909. A limited sub-programme on the sensitivity of hold times at elevated temperature at zero force conditions and at elevated temperature did not show the beneficial effect on fatigue life found in another study.

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Chen, Xingyang, Linlin Ma, Haoping Xie, Fengting Zhao, Yufeng Ye, and Lin Zhang. "Effects of external hydrogen on hydrogen-assisted crack initiation in type 304 stainless steel." Anti-Corrosion Methods and Materials 67, no. 3 (April 27, 2020): 331–35. http://dx.doi.org/10.1108/acmm-02-2020-2258.

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Purpose The purpose of this paper is to present a crack initiation mechanism of the external hydrogen effect on type 304 stainless steel, as well as on fatigue crack propagation in the presence of hydrogen gas. Design/methodology/approach The effects of external hydrogen on hydrogen-assisted crack initiation in type 304 stainless steel were discussed by performing fatigue crack growth rate and fatigue life tests in 5 MPa argon and hydrogen. Findings Hydrogen can reduce the incubation period of fatigue crack initiation of smooth fatigue specimens and greatly promote the fatigue crack growth rate during the subsequent fatigue cycle. During the fatigue cycle, hydrogen invades into matrix through the intrusion and extrusion and segregates at the boundaries of α′ martensite and austenite. As the fatigue cycle increased, hydrogen-induced cracks would initiate along the slip bands. The crack initiation progress would greatly accelerate in the presence of hydrogen. Originality/value To the best of the authors’ knowledge, this paper is an original work carried out by the authors on the hydrogen environment embrittlement of type 304 stainless steel. The effects of external hydrogen and argon were compared to provide understanding on the hydrogen-assisted crack initiation behaviors during cycle loading.

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FUKUTA, Yuichi, Hiroshi KANASAKI, Seiji ASADA, and Toshiya SARUWATARI. "OS0803 Refinement of Strain Rate that Shows No Environment Assisted Fatigue for Austenitic Stainless Steels in PWR Environment." Proceedings of the Materials and Mechanics Conference 2012 (2012): _OS0803–1_—_OS0803–3_. http://dx.doi.org/10.1299/jsmemm.2012._os0803-1_.

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Octavia, Johanna Renny, Peter Feys, and Karin Coninx. "Development of Activity-Related Muscle Fatigue during Robot-Mediated Upper Limb Rehabilitation Training in Persons with Multiple Sclerosis: A Pilot Trial." Multiple Sclerosis International 2015 (2015): 1–11. http://dx.doi.org/10.1155/2015/650431.

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Robot-assisted rehabilitation facilitates high-intensity training of the impaired upper limb in neurological rehabilitation. It has been clinically observed that persons with Multiple Sclerosis (MS) have difficulties in sustaining the training intensity during a session due to the development of activity-related muscle fatigue. An experimental observational pilot study was conducted to examine whether or not the muscle fatigue develops in MS patients during one session of robot-assisted training within a virtual learning environment. Six MS patients with upper limb impairment (motricity index ranging from 50 to 91/100) and six healthy persons completed five training bouts of three minutes each performing lifting tasks, while EMG signals of anterior deltoid and lower trapezius muscles were measured and their subjective perceptions on muscle fatigue were registered. Decreased performance and higher subjective fatigue perception were present in the MS group. Increased mean EMG amplitudes and subjective perception levels on muscle fatigue were observed in both groups. Muscle fatigue development during 15′ training has been demonstrated in the arm of MS patients, which influences the sustainability of training intensity in MS patients. To optimize the training performance, adaptivity based on the detection of MS patient’s muscle fatigue could be provided by means of training program adjustment.

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Poulain, Thibault, Laurent de Baglion, Jose Mendez, and Gilbert Hénaff. "Influence of Strain Rate and Waveshape on Environmentally-Assisted Cracking during Low-Cycle Fatigue of a 304L Austenitic Stainless Steel in a PWR Water Environment." Metals 9, no. 2 (February 8, 2019): 197. http://dx.doi.org/10.3390/met9020197.

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In this paper, the low cycle fatigue resistance of a 304L austenitic stainless steel in a simulated pressurized water reactor (PWR) primary water environment has been investigated by paying a special attention to the interplay between environmentally-assisted cracking mechanisms, strain rate, and loading waveshape. More precisely, one of the prime interests of this research work is related to the consideration of complex waveshape signals that are more representative of solicitations encountered by real components. A detailed analysis of stress-strain relation, surface damage, and crack growth provides a preliminary ranking of the severity of complex, variable strain rate signals with respect to triangular, constant strain-rate signals associated with environmental effects in air or in PWR water. Furthermore, as the fatigue lives in PWR water environment are mainly controlled by crack propagation, the crack growth rates derived from striation spacing measurement and estimated from interrupted tests have been carefully examined and analyzed using the strain intensity factor range ΔKε. It is confirmed that the most severe signal with regards to fatigue life also induces the highest crack growth enhancement. Additionally two characteristic parameters, namely a threshold strain εth* and a time T*, corresponding to the duration of the effective exposure of the open cracks to PWR environment have been introduced. It is shown that the T* parameter properly accounts for the differences in environmentally-assisted growth rates as a function of waveshape.

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Дисертації з теми "Environment-assisted fatigue"

Larippe, Laure. "Étude du comportement en fatigue des câbles d'acier sous environnement et chargement variables." Electronic Thesis or Diss., université Paris-Saclay, 2022. http://www.theses.fr/2022UPAST121.

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Les pneumatiques poids lourds sont renforcés par des câbles d'acier pour reprendre lestensions générées par la pression de gonflage et le poids du véhicule. Le câble est un assemblage de fils perlitiques tréfilés enroulés en hélice sur plusieurs couches. Le comportement mécanique d'un câble est fonction de son architecture ainsi que des possibilités matériaux-procédés existantes à l'échelle du fil. En service, le câble est soumis à une combinaison complexe de sollicitations cycliques de type mécanique et chimique conduisant à un endommagement en fatigue. Pour réduire l'impact environnemental, ces câbles sont visés par une stratégie d'allégement, viable uniquement à performances similaires ou supérieures. Une condition préalable à l'introduction de nouveaux matériaux dans un pneu est donc le développement de modèles fiables prédisant la durée de vie en fatigue des câbles, ce qui implique la compréhension des mécanismes de fatigue.Par simplification, l'étude s'est portée à l'échelle du fil unitaire (diamètre 180 µm). Différents types de fils ont été produits par l'industriel faisant varier des paramètres influents en fatigue. Un essai de fatigue en traction ondulée sous environnement contrôlé représentatif de la sollicitation en service a été mis au point. Les paramètres matériaux-procédé-environnement impliqués dans l'amorçage et la propagation des fissures sont identifiés par la construction de courbes de Wöhler. Des essais de suivi de propagation in-situ de fissures au sein du fil ont été réalisés en environnement contrôlé sous rayonnement synchrotron pour des rapports de charge positifs. Les lois de Paris et les paramètres impactant celles-ci ont été obtenus.L'ensemble des expériences a permis de dégager les mécanismes physiques impliqués et d'identifier les paramètres correspondants. Un modèle prédictif a été développé à l'échelle du fil. Basé sur la propagation d'une distribution de défauts de surface, il estime une durée de vie du fil pour une sollicitation mécanique et chimique donnée
Heavy duty tyres are reinforced with steel cords to take up the stresses generated by the inflation pressure and the weight of the vehicle. The cable is an assembly of drawn wires helically wound in several layers. The mechanical behaviour of a cable is a function of its architecture as well as the material-processing possibilities available at the wire scale. In service, the cable is subjected to a complex combination of cyclic mechanical and chemical stresses leading to fatigue damage. To reduce the environmental impact, these cables are targeted by a lightweighting strategy, viable only at similar or better performance. A prerequisite for the introduction of new materials in a tyre is therefore the development of reliable models predicting the fatigue life of the cords, which implies an understanding of the fatigue mechanisms. For simplicity, the study was carried out at the unit wire scale (180 µm diameter).Different types of wires were produced by the manufacturer, varying the parameters that have an influence on fatigue. A tensile-tensile fatigue test under a controlled environment representative of the stress in service was developed. The material-process-environment parameters involved in crack initiation and propagation are identified by constructing Wöhler curves. In-situ crack propagation monitoring tests within the wire were performed in a controlled environment under synchrotron radiation for positive load ratios. The Paris laws and the parameters impacting them were obtained.All the experiments made it possible to identify the physical mechanisms involved and the corresponding parameters. A predictive model was developed at the wire scale. Based on the propagation of a distribution of surface defects, it estimates the life of the wire for a given mechanical and chemical stress

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Книги з теми "Environment-assisted fatigue"

1944-, Scott P., and Cottis R. A, eds. Environment assisted fatigue. London: Mechanical Engineering Publications, 1990.

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Environment Assisted Fatigue (EGF 7) (Egf Publication). Wiley, 2005.

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Частини книг з теми "Environment-assisted fatigue"

Gdoutos, Emmanuel E. "Fatigue and Environment-Assisted Fracture." In Fracture Mechanics, 287–320. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-35098-7_9.

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Gdoutos, Emmanuel E. "Fatigue and Environment-Assisted Fracture." In Fracture Mechanics, 265–92. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-015-8158-5_9.

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Gdoutos, E. E. "Fatigue and environment-assisted fracture." In Fracture Mechanics Criteria and Applications, 255–77. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-1956-3_8.

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Turnbull, A. "Environment-assisted Fatigue in Liquid Environments." In Comprehensive Structural Integrity, 163–210. Elsevier, 2003. http://dx.doi.org/10.1016/b0-08-043749-4/06131-0.

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AKID, R. "Modelling Environment-Assisted Short Fatigue Crack Growth." In Advances in Fracture Resistance and Structural Integrity, 261–69. Elsevier, 1994. http://dx.doi.org/10.1016/b978-0-08-042256-5.50032-9.

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Тези доповідей конференцій з теми "Environment-assisted fatigue"

Solin, Jussi, Tommi Seppänen, Rami Vanninen, Erkki Pulkkinen, and Petri Lemettinen. "Environment Assisted Fatigue – Experimental Challenges and Solutions." In ASME 2022 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/pvp2022-84719.

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Abstract The design fatigue curves applied for safety class 1 components in NPP’s are based on an experimentally determined strain-life fatigue data, the resulting ε-N reference curves and transferability margins. To account for detrimental effects of coolant water environment, penalty factors (Fen) are obtained by comparing fatigue lives in air and environment. To avoid bias in comparison, the same fatigue testing procedures according to ASTM E606 would be preferred in both environments. However, modified EAF test procedures were developed when direct control of strain in the specimen gauge section was not possible. This paper introduces and discusses commonly used experimental approaches for conducting (directly or remotely) strain-controlled fatigue tests in simulated LWR coolant water environments. At or near gauge section remotely controlled and tubular specimens have been successfully used to determine penalty factors for fatigue usage in environment, but variation and uncertainties related to experimental methods used for collecting the data cannot be completely excluded. The challenges and solutions adopted during latest 20 years in Finland are explained.

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Solin, Jussi, Tommi Seppänen, Petri Lemettinen, Rami Vanninen, and Erkki Pulkkinen. "Environment Assisted Fatigue – Rules, Assumptions and Challenges for Fatigue Management of Primary Piping." In ASME 2022 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/pvp2022-84627.

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Abstract This paper introduces and discusses the commonly used methods for calculating environmental penalty factors (Fen) to be used in fatigue assessment of stainless reactor components. Three alternative methods for determining Fen factors are introduced and instructed in the JSME S NF1-2009 Code in a language providing a designer the guidance needed for reliable and repeatable EAF assessment. Following these instructions together with the equations and parameters given in the NUREG/CR-6909 it is possible to obtain same Fen factors as by careful reading of the NUREG/CR-6909 alone. The NUREG/CR-6909, Rev. 1 contains notable amounts of valuable information, but instructions for application can be ambiguous or conflicting. An example related to the modified strain rate approach for determining Fen factors is provided.

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Solin, Jussi, Tommi Seppänen, Rami Vanninen, Erkki Pulkkinen, Petri Lemettinen, and Claude Faidy. "Codes, Standards, Rules and Assumptions on Environment Assisted Fatigue for Fatigue Management of Primary Piping." In ASME 2020 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/pvp2020-21501.

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Abstract All international codes used for design, operation and inspection of NPP primary circuit pressure boundaries are rooted to the ASME Boiler and Pressure Vessel Code, Section III, Nuclear Vessels, 1963. Article 4, N-415 “Analysis for cyclic operation” instructed calculation of stress intensities for fatigue transients and provided two design curves for basic material types. Different codes such as ASME, RCC-M, KTA, PNAE and JSME have much in common, but partial deviations exist. In 2007 the US NRC Regulatory Guide 1.207 endorsed a methodology for accounting the environmental effects. It was mainly based on extensive work in Japan and the Argonne National Laboratory. The final report of ANL, NUREG/CR-6909 became a major reference and subject of criticism. However, the first approach for environment assisted fatigue (EAF) written in ‘code language’ was published in Japan and a regulatory requirement for consideration of EAF both for operating reactors and new designs appeared first in Finland. This paper discusses challenges in management of fatigue and the evolving state-of-the-art in different codes, standards, rules and assumptions. The roots and current status of fatigue curves and design criteria applied in Finnish NPP’s are explained.

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Fukuta, Yuichi, Yuichiro Nomura, Toshiya Saruwatari, and Seiji Asada. "High Strain Rate Effects on Environment Assisted Fatigue for Austenitic Stainless Steels in PWR Environment." In ASME 2013 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/pvp2013-97158.

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Current Japanese fatigue evaluations in the PWR environment are conducted using JSME S NF1 in which some parameters (temperature, strain rate, dissolved oxygen, etc.) are evaluated as influencing factors. However, it is assumed that the JSME Code would be conservative in high-strain-rate regions because the environmental factor (Fen) is evaluated by extrapolating experimental test results from a low strain rate (up to 0.4%/sec). In this study, experimental data are obtained additionally and Fen for high-strain-rate regions are reevaluated. As a result, it is confirmed that Fen at a strain rate of 1.0%/sec is about one half of that in the JSME Code. Further, marshaled experimental data obtained from the EFT project, which are classified according to stainless grade and material charge, indicated that the strain rate at Fen = 1 can be lower than 3%/sec for all austenitic stainless steels and similar to the current test result.

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Bruchhausen, Matthias, Alec McLennan, Roman Cicero, Caitlin Huotilainen, Kevin Mottershead, Jean-Christophe le Roux, and Marc Vankeerberghen. "Environmentally Assisted Fatigue Data From the INCEFA-PLUS Project." In ASME 2019 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/pvp2019-93085.

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Abstract The European project INCEFA-PLUS characterises environmentally assisted fatigue in light water reactor conditions. The project aims at developing a new procedure to assess environmentally assisted fatigue damage susceptibility in nuclear power plant components. The basis for the development of a new fatigue assessment procedure is a major test campaign carried out in eleven different laboratories across Europe which will deliver approximately 200 fatigue tests. The test campaign is based on a common test matrix that was optimized by means of the Design of Experiments method. The initial focus of the project is on the effects and interactions between the factors strain range, environment (air and light water reactor environment), surface finish, hold time, and mean strain. Whereas the bulk of the test program is carried out on a single heat of 304L austentic steel, some tests on different heats of 304L or other austenitic steels allow studying the influence of material variability. To guarantee the quality of the data, the tests are performed according to commonly agreed specifications based on ISO 12106 and each test is validated by a group of experts from within the project. The paper presents the test procedures, provides an overview of the data that has been acquired so far, and gives an outlook on the tests that will be carried out during the final stage of the project.

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Yonggang, Fang, Zhan Jiashuo, Chu Qibao, Wang Qing, and Xu Yu. "Effect of Reactor Coolant Environment on Fatigue Property of Austenitic Stainless Steel in PWR." In 2017 25th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/icone25-67734.

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It is required that the fatigue analysis be done for nuclear reactor components consisting of the reactor pressure boundary. Currently, it is certified that the fatigue design curves currently used in the analysis weren’t conservative enough for not considering reactor coolant environment. The article gives some general information related with the regulatory requirements and research work conducted abroad. It introduces coolant environment assisted fatigue experiment based on the domestic austenitic stainless steels and provides the data comparison with the code design fatigue curves. It concludes and recommends the methodology for the nuclear component fatigue design.

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Swacek, Christian, Ludwig Stumpfrock, and Stefan Weihe. "Investigations on the Environmentally Assisted Fatigue Behavior of Steel Specimens for a Better Understanding of Component Fatigue in Nuclear Applications." In ASME 2021 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/pvp2021-61961.

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Abstract The fatigue assessment of pressurized components is of high importance for the operation of nuclear power plants. However, the environmental influences on the fatigue behavior are highly discussed. On the one hand, laboratory specimens tested in high temperature water (HTW) conditions show a significant drop in fatigue lifetime, compared to tests at air environment, and question the conservatism of modern standards. On the other hand, the fatigue assessment methods based on uniaxial tensile testing seems to overestimate the fatigue damage of components during operation. To overcome these discrepancies, the environmental influences on material fatigue have to be better understood. Laboratory testing setups have to be adapted to the relevant loading conditions during power plant operation. Therefore, MPA Stuttgart is investigating the environmentally assisted fatigue (EAF) of steels under various loading conditions for smooth and notched specimens, as well as full scale component testing at HTW conditions. In this paper the results of ongoing research are presented. The low cycle fatigue experiments on steel materials for relevant nuclear applications are performed at air and under pressurized water reactor (PWR) environment. The shape of specimens, the loading spectra, loading rate and the multiaxiality of load are derived from piping components in power plant operation.

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Asada, Seiji, Daiki Takagoshi, Yuichi Fukuta, Kazuya Tsutsumi, Kawaljit Ahluwalia, and David Steininger. "Study on Effects of Non-Isothermal Condition and Strain Holding on Environmentally Assisted Fatigue in PWR Primary Water Environment: Step II." In ASME 2017 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/pvp2017-66233.

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In order to understand the fatigue behavior in PWR primary water environment, the influence of non-isothermal transient condition was investigated for austenitic stainless steel 316SS. In our previous study (PVP2016-63798), isothermal and non-isothermal environmentally assisted fatigue tests were performed. The fatigue life of the non-isothermal fatigue test consisted of a high temperature and tensile strain rate transient, a portion of which occurred in the compressive strain region of the strain cycle. The result of this test showed longer life than the predicted fatigue life estimated by the modified rate approach and Fen factor as presented in NUREG/CR-6909 Rev.1. In this paper, the reason why the fatigue test showed longer fatigue life is studied. Crack growth analysis was performed to understand the effect of the environment on fatigue life. Additionally, application of the Weighted K Rate (WKR) method described in reference (PVP2016-63497) was applied to a series of tests. This approach showed good agreement on fatigue life for a number of different waveforms for isothermal tests. The methodology was applied to some of this investigation’s non-isothermal fatigue tests and shown to be an improvement that justifies further investigation.

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Asada, Seiji, Yuichi Fukuta, Kawaljit Ahluwalia, and David Steininger. "Study on Effects of Non-Isothermal Condition and Strain Holding on Environmentally Assisted Fatigue in PWR Primary Water Environment." In ASME 2016 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/pvp2016-63798.

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To understand the fatigue behavior of austenitic stainless steels in a simulated PWR primary water environment, the patterns were studied. Austenitic stainless steel Type 316 plate was used as the test material. Regarding non-isothermal testing: isothermal and non-isothermal fatigue tests were carried out for several patterns of temperature change and strain rate change. Typically, fatigue lives for non-isothermal tests with an out-of-phase strain change pattern were longer than those for isothermal tests. Regarding strain holding testing: multiple groups of strain range cycles were separated by a long hold time and several test cases were carried out. Testing shows there is little difference in fatigue life for strain holding tests with high strain amplitude.

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Reese, Sven H., Johannes Seichter, and Dietmar Klucke. "Consideration of Environmentally Assisted Fatigue in Austenitic Stainless Steel: Calculation and Practical Application." In ASME 2012 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/pvp2012-78107.

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Анотація:

The influence of LWR coolant environment to the lifetime of materials has been discussed recent years. Nowadays the consideration of environmentally assisted fatigue is under consideration in Codes and Standards like ASME and the German KTA Rules (e.g. Standard No. 3201.2 and Standard No. 3201.4) by means of so called attention thresholds. Basic calculation procedures in terms of quantifying the influence of LWR coolant environment by the Fen correction factor were proposed by Higuchi and others and are given in NUREG/CR-6909. This paper deals with the application of the proposed assessment procedures of ANL and the application to plant conditions. Therefore conservative assessment procedures are introduced without assuming the knowledge of detailed stress and strain calculations or temperature transients. Additionally, detailed assessment procedures based on Finite-Element calculations, respecting in-service temperature measurements including thermal reference transients and complex operational loading conditions are carried out. Fatigue evaluation of a PWR primary circuit component is used in order to evaluate the influence of plant like conditions numerically. Conclusions regarding the practical application are drawn by means of comparing the ANL approach considering laboratory conditions, conservative assessment procedures for the determination of cumulative fatigue usage factors of plant components and detailed assessment procedures. Plant like loading conditions, complex component geometries, loading scenarios and reference temperature transients shall be taken into account. Practical issues like the determination of the mean temperature or the strain rate have to be considered adequately.

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