Study on hold-time effects in environmental fatigue lifetime of low-alloy steel and austenitic stainless steel in air and under simulated PWR primary water conditions

Abstract

This paper summarizes the results of a research project on environmental effects on the fatigue lifetime of selected low-alloy steels and austenitic stainless steels. Results from investigations on the effect of hold times during fatigue in air, as well as under simulated PWR primary water conditions are presented. Strain controlled fatigue tests with low strain rates and low strain amplitudes have been performed in air using a low-alloy RPV steel as well as the stabilized austenitic stainless steel 347 and the non-stabilized austenitic stainless steel 304L. Similar strain controlled tests under simulated PWR primary coolant conditions were performed using the two above mentioned austenitic stainless steels. The fatigue cycling was performed at 240 °C whereas holds were applied at higher temperature (290 °C). The effect of hold periods is compared to reference tests without hold times and to the prediction based on NUREG/CR 6909, Rev. 1.