Fatigue Strength Evaluation of Austenitic Stainless Steel with Some Artificial Corrosion Pits

Abstract

In order to investigate the effect of stress concentration on high cycle fatigue strength of austenitic stainless with corrosion pits, rotating bending fatigue tests were carried out. In this study, two types of austenitic stainless steels were used. One is Type 316 NG which is using for nuclear power generation plant and another one is Type 304 TP which is using as a pipe of industrial plants. The fatigue tests were carried out using the notch specimen which has some artificial corrosion pits on the center part of the specimens. The fatigue strength at 10⁸ cycle of specimen having some artificial corrosion pits was much lower than that of specimen without pits and all fatigue cracks were generated from the pits. To evaluate the fatigue crack initiation property from the pits, stress concentration factor was estimated by its depth and its diameter which were measured using optical microscope. As that results, the values of stress concentration factor of pits were about estimated as values from 1.5 to 2.2. The fatigue crack initiation property from pits was explained by treating a stress concentration factor as fatigue strength reduction factor.