Effects of Strain Rate Change on Fatigue Life of Carbon Steel in High-Temperature Water

2009 ◽  
pp. 216-216-16 ◽  
Author(s):  
M Higuchi ◽  
K Iida ◽  
Y Asada
Keyword(s):  
High Temperature ◽  
Fatigue Life ◽  
Carbon Steel ◽  
Strain Rate ◽  
Rate Change ◽  
Strain Rate Change ◽  
High Temperature Water ◽  
Temperature Water

scholarly journals Surface Composition and Corrosion of SS 41 Carbon Steel in High Temperature Water under γ-ray Irradiation

1982 ◽  
Vol 31 (4) ◽  
pp. 254-260
Author(s):  
Akihisa Sakumoto ◽  
Masao Gotoda ◽  
Yuji Horii ◽  
Hidetaka Konno ◽  
Hiroki Tamura ◽  
...  
Keyword(s):  
High Temperature ◽  
Carbon Steel ◽  
Gamma Ray ◽  
Surface Composition ◽  
High Temperature Water ◽  
Gamma Ray Irradiation ◽  
Temperature Water

Role of Cavity Formation in Crack Initiation of Cold-Worked Carbon Steel in High-Temperature Water

CORROSION ◽  
10.5006/0821 ◽  
2013 ◽  
Vol 69 (5) ◽  
pp. 487-496 ◽  
Author(s):  
Koji Arioka ◽  
Tomoki Miyamoto ◽  
Takuyo Yamada ◽  
Masanori Aoki
Keyword(s):  
High Temperature ◽  
Carbon Steel ◽  
Crack Initiation ◽  
Cavity Formation ◽  
High Temperature Water ◽  
Cold Worked ◽  
Temperature Water

Evaluation of Environmental Effects on the Fatigue of Notched Specimen of Austenitic Stainless Steel Using Modified Rate Approach Method

2004 ◽  
Author(s):  
Katsumi Sakaguchi ◽  
Yasuhide Asada ◽  
Masao Itatani ◽  
Toshiyuki Saito
Keyword(s):  
Stainless Steel ◽  
High Temperature ◽  
Fatigue Life ◽  
Stress Concentration ◽  
Austenitic Stainless Steel ◽  
Notch Root ◽  
Notched Specimen ◽  
High Temperature Water ◽  
Approach Method ◽  
Temperature Water

Fatigue testing was conducted on notched specimens of austenitic stainless steel 316NG in high temperature water. Specimens were notched round bar with elastic stress concentration factors Kt of 1.4 and 3. For the specimen of Kt = 3, fatigue test was also performed in high temperature air. Environmental correction factor Fen recently proposed by Environmental Fatigue Tests (EFT) project in Japan Nuclear Safety Organization (JNES) was applied to the result of fatigue test to evaluate the environmental effects on fatigue life of notched specimen. Since the notch root strain varies non-proportionally to nominal strain in the elastic-plastic region, the modified rate approach method was applied to predict the fatigue life of notched specimen in the water, which was proposed to account for the environmental effect on fatigue life of nuclear component materials under varying conditions. Notch root strain and strain rate were calculated by FEM analysis. The difference between predicted and experimental fatigue lives in high temperature water was within factor of 2 for Kt = 3. The relationships between fictitious stress amplitude at notch root (= notch root strain amplitude multiplied by elastic modulus) and corrected fatigue life shows good coincidence with best fit curve for austenitic stainless steels. It is concluded that the modified rate approach method and current environmental correction factor Fen proposed by EFT project is applicable to predict fatigue life of the stress concentration when the notch root strain is adequately estimated.

Thermo-Mechanical Loading of Full-Scale Welded Piping Components in High Temperature Water Environment

2017 ◽  
Author(s):  
Matthias C. Kammerer ◽  
Xaver Schuler ◽  
Stefan Weihe ◽  
Michael Seidenfuß ◽  
Mi Zhou ◽  
...  
Keyword(s):  
High Temperature ◽  
Fatigue Life ◽  
Fatigue Testing ◽  
Water Environment ◽  
Hot Water ◽  
Component Level ◽  
High Temperature Water ◽  
Weld Material ◽  
Nickel Base ◽  
Temperature Water

The effect of high-temperature water environment on the fatigue life of steels used for pressure retaining components has been discussed controversially for the last 20 to 30 years. Fatigue testing of laboratory specimens for typical steels showed significant drops in fatigue life when tested in high temperature water environment compared to air environment. Based on these findings the applicability of fatigue design curves such as those enclosed to ASME code Section III NB are questionable concerning their degree of conservatism. Nevertheless, experience from components experiencing power plant operation does not match up with laboratory fatigue testing of small uniaxial specimens. Fatigue life estimations based on models representing laboratory tests do highly overestimate the fatigue life reduction resulting from high temperature water environments compared to the analyses of components having reached their postulated fatigue life. To overcome this disagreement component testing under defined laboratory conditions is highly desired to achieve “gap closure”. At MPA University of Stuttgart a test facility was set up where environmental fatigue testing on component level can be realized within a hot water test loop. Within the framework of a research project sponsored by the German Federal Ministry of Education and Research (BMBF) piping modules containing a dissimilar metal weld are exposed to water environments with alternating temperature conditions. At specific locations water at about room temperature is injected to a hot pipe segment which results in thermal induced loading situations. Consequently thermal stratification and shocks cause localized stresses and strains in the tested modules. Within this paper an overview of the testing procedure, the tested materials and results from both experimental measurements and fractographic analyses are presented and discussed. In addition to experimental investigations the results drawn from a coupled computational fluid dynamics (CFD) and structural mechanics finite-element-analysis (FEA) including a fatigue life assessment are shown. Finally, this work states on the applicability of common fatigue assessment procedures including the fatigue life reducing factors based on the results from realistic fatigue testing on component level. Within low cycle fatigue tests a nickel-base weld material was characterized regarding its fatigue life in air and high temperature water environment in comparison. It was found that the effect of environmentally assisted fatigue is in good agreement with what is known from literature for smooth specimens made from austenitic steels. Results from tests using notched specimens showed a significant change in the environmental effect compared to tests using smooth specimens. During component testing within a hot water loop modules which contain a dissimilar metal weld were exposed to alternating water temperature conditions between 20 °C and 65 °C. At the end of the component test cracks were found in the regions where the highest temperature changes were measured and calculated. The numerical analysis of the fluid-structure-interaction pointed out that the transition region between the austenitic steel and the nickel base weld material is the highest loaded section within the module. Finally the fatigue assessment of the pipe sections containing cracks showed that based on common fatigue hypothesis the loading state is regarded to be subcritical.

Low Temperature Deformation Kinetics of Ruthenium Aluminide Alloys

1998 ◽  
Vol 552 ◽  
Author(s):  
D. C. Lu ◽  
T. M. Pollock
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Strain Rate ◽  
Rate Change ◽  
The Other ◽  
Temperature Deformation ◽  
Strain Rate Change ◽  
Deformation Kinetics ◽  
Ruthenium Aluminide ◽  
Kinetics Of

ABSTRACTThe kinetics of low temperature deformation were investigated in several different polycrystalline RuAl alloys with the use of strain rate change experiments at 77 K and 298 K. Compositions investigated include RuAl, RuAl+0.5%B, Ru51.5 A48.5, Ru52 Al48, RU53 A147+0.5%B, Ru54.5 Al45.5, and Ru52 Al43 Sc5. Flow stresses did not vary substantially with temperature between 77 K and 298 K. Rate sensitivities were low compared to other B2 compounds and similar in all compositions investigated. Analyses of dislocation substructures after low strain deformation were conducted. The deformation kinetics and substructural observations suggest a higher intrinsic deformability for RuAI alloys with respect to the other high temperature B2 aluminides.

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