Damage evaluation based on advanced measurement of austenitic steel SUS316L

Abstract

The electron backscatter diffraction (EBSD) and positron annihilation methods applied to analysis of low-cycle fatigue damage in an austenitic stainless steel (SUS316L) which is mostly used in primary water line of power reactor. Samples of various degrees of low-cycle fatigue with strain control from room temperature to high temperature were prepared for the above measurement methods. The average of misorientation obtained by KAM (Kernel Average Misorientation) showed a proportional increase with the fatigue damage to cycle to fatigue, Nf. As compared with the sample of room temperature fatigue damage, the that of high temperature fatigue damage decreased slightly the average of misorientation at each cycles. It was considered to be due to the recovery of the dislocation. Positron annihilation lifetime measurements showed an increase in the positron lifetime for fatigued SUS316L samples compared to the as-received sample.