Environmental effect on fatigue strength of stainless steel in PWR primary water: Relation between fatigue life in air and environment

Abstract

The fatigue life of Type 316 stainless steel in the pressurized water reactor (PWR) water environment and its dependency on that in air were investigated. Specimens from two heats of the material were prepared for fatigue tests, and additionally, previous test findings obtained using another heat were applied. The fatigue test results obtained for various strain ranges and strain rates revealed that the fatigue life in the water environment Nf(env) did not depend on that in air Nf(air) when the strain rate was 0.4%/s. The variation in the ratio of Nf(env) to Nf(air) was larger when Nf(air) obtained for each heat of the material was used than that when a general Nf(air) was used. The changes in the penalty factor Fen with applied strain range and strain rate could be predicted by assuming Nf(env) depended not on strain rate but on rise time.