저주기 피로변형시 316L 스테인리스강의 비안정화 거동에 미치는 온도의 영향: 반복응력거동 및 적정 피로수명인자

Abstract

In this study, cold worked (CW) 316L austenitic stainless steel was investigated by performing low-cycle fatigue test with varying temperature, strain amplitude, and strain rate. CW 316L stainless steel underwent additional hardening at room temperature and in the temperature range of 250-600℃: The hardening at room temperature came from plasticity-induced martensite transformation, and the hardening over 250-600℃ was attributed to dynamic strain aging. These hardening mechanisms competed with the softening mechanism which was induced by dynamic recovery, generally observed in cold worked materials, resulting in the cyclical non-stabilization of the material. Three fatigue parameters, such as stress amplitude, plastic strain amplitude, and plastic strain energy density, were evaluated. The results revealed that plastic strain energy density was nearly invariant through a whole life and, thus, recommended as a suitable fatigue parameter. (Received September 3, 2004)