S0302-3-3 Effect of Load Variation of Prediction of the Onset of Crack Growth for Low-Cycle Fatigue of Stainless Steel Studied Using Ultrasonic Back-Reflection

2010 ◽  
Vol 2010.1 (0) ◽  
pp. 81-82
Author(s):  
Md. Nurul Islam ◽  
Yoshio ARAI ◽  
Wakako ARAKI
Keyword(s):  
Stainless Steel ◽  
Crack Growth ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Back Reflection ◽  
Load Variation

scholarly journals 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 ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 197 ◽  
Author(s):  
Thibault Poulain ◽  
Laurent de Baglion ◽  
Jose Mendez ◽  
Gilbert Hénaff
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Strain Rate ◽  
Crack Growth ◽  
Growth Rates ◽  
Low Cycle Fatigue ◽  
Water Environment ◽  
Cycle Fatigue ◽  
Pressurized Water ◽  
Environmentally Assisted Cracking

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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