Threshold for Fatigue Crack Growth in Ferritic Steels at 300 C

2009 ◽  
pp. 179-179-13 ◽  
Author(s):  
LP Pook ◽  
AA Beveridge
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Ferritic Steels

Construction of a fatigue-crack-growth database for nuclear-component ferritic steels in Japan and its statistical analysis

1990 ◽  
Vol 44 (1) ◽  
pp. 67-83 ◽  
Author(s):  
Hideo Kobayashi ◽  
Haruo Nakamura ◽  
Ken-ichi Kasai ◽  
Masahiro Saito ◽  
Tatsuo Funada ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Statistical Analysis ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Ferritic Steels ◽  
Nuclear Component

An Assessment of Low Alloy Steel EAC Corrosion Fatigue Relationships for BWR Environment

2005 ◽  
Author(s):  
Hardayal Mehta ◽  
Ron Horn
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Water Chemistry ◽  
Crack Growth ◽  
Corrosion Fatigue ◽  
Growth Rates ◽  
Ferritic Steels ◽  
Asme Code ◽  
Crack Growth Rates

The fatigue crack growth rates for ferritic steels in water environments given in A-4300 of Appendix A, Section XI, ASME Code, were developed from data obtained prior to 1980. Subsequently, updated assessments by Eason, et al. and recent laboratory test results from Seifert and Ritter demonstrated that under certain conditions, ferritic steels exposed to oxygenated water environments may be susceptible to high fatigue crack growth rates that exceed the current disposition curves. In the light of ASME adopting Code Case N-643 for PWRs, there is a need for a similar Code Case for the BWR water environments (for both the normal water chemistry and hydrogen water chemistry/NobleChem) that takes into account these findings. This could mean modification of current EAC curves in the ASME Code. A joint program of EPRI and GE was developed to address this need for updated evaluations of the corrosion fatigue. The program’s first task has been to re-assess the role of rise time, environment, alloy, heat treatment and impurity levels on the established ASME codified disposition curves/methodologies. The data was then used as a basis to assess the impact of on modified cyclic curves on the disposition approaches that are currently used to evaluate postulated flaws in the BWR reactor pressure vessel or RPV head and the feed water nozzle regions. The presentation would include a discussion of the appropriate BWR plant transients and the GE process for performing evaluations. The role of the evaluations on the establishment of inspection intervals currently determined using NUREG-0619 and the latest BWROG Report would also be presented. Finally, the relationship between cyclic load and constant load behavior in these steels are discussed in the context of the mechanisms for environmentally assisted cracking.

Fatigue Crack Growth Rates for Ferritic Steels Under Negative R Ratio

2016 ◽  
Author(s):  
Kunio Hasegawa ◽  
Vratislav Mares ◽  
Yoshihito Yamaguchi ◽  
Yinsheng Li
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Closure ◽  
Growth Rates ◽  
Ferritic Steels ◽  
R Ratio ◽  
Asme Code ◽  
Reference Curves ◽  
Crack Growth Rates

Reference curves of fatigue crack growth rates for ferritic steels in air environment are provided by the ASME Code Section XI Appendix A. The fatigue crack growth rates under negative R ratio are given as da/dN vs. Kmax, It is generally well known that the growth rates decreases with decreasing R ratios. However, the da/dN as a function of Kmax are the same curves under R = 0, −1 and −2. In addition, the da/dN increases with decreasing R ratio for R < −2. This paper converts from da/dN vs. Kmax to da/dN vs. ΔKI, using crack closure U. It can be obtained that the growth rates da/dN as a function of ΔKI decrease with decreasing R ratio for −2 ≤ R < 0. It can be seen that the growth rate da/dN vs. ΔKI is better equation than da/dN vs. Kmax from the view point of stress ratio R. Furthermore, extending crack closure U to R = −5, it can be explained that the da/dN decreases with decreasing R ratio in the range of −5 ≤ R < 0. This tendency is consistent with the experimental data.

A Review of Fatigue Crack Growth Thresholds for Metals in Fitness-for-Service Codes: On the Uncertainty of Using the Thresholds at Negative Stress Ratios

2021 ◽  
Author(s):  
Kunio Hasegawa ◽  
Bohumir Strnadel ◽  
Vratislav Mares ◽  
David Dvorak ◽  
Saburo Usami
Keyword(s):  
Stainless Steel ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Stainless Steels ◽  
Ferritic Steel ◽  
Literature Survey ◽  
Ferritic Steels ◽  
Section Viii ◽  
Stress Ratios

Abstract Fatigue crack growth thresholds deltaKth for metals are provided in many fitness-for-service codes. However, fatigue thresholds at negative stress ratios are not uniform. There are two forms of thresholds at negative stress ratios: constant thresholds irrespective of stress ratios, or increasing thresholds with decreasing stress ratios. The definitions of the thresholds at negative stress ratios also take two forms: either deltaKth = Kmax - Kmin, or deltaKth = Kmax. ASME Section VIII, Section XI (ferritic steel) and IIW give constant thresholds expressed by deltaKth = Kmax. API 579 and ASME Section XI (stainless steel) give increases in thresholds with decreasing stress ratios and the thresholds are expressed by deltaKth = Kmax - Kmin. BS 7910 gives constant thresholds expressed by deltaKth = Kmax - Kmin. The fatigue thresholds differ significantly among different FFS codes. Appropriate thresholds for ferritic steels, stainless steels and aluminum alloys are demonstrated in the literature survey.

Sign in / Sign up

Export Citation Format

Share Document