316L 스테인리스강의 고온 저주기 피로저항에 미치는 동적변형시효의 영향

Abstract

Mechanism of dynamic strain aging (DSA) and its effect on the low-cycle fatigue (LCF) behavior in type 316L stainless steel were investigated by performing LCF tests in air in a wide temperature range from 20 to 650℃ with strain rates of 3.2x10^(-5)-1x10^(-2)/s. The regime of DSA was evaluated using the anomalies associated with DSA and was in the temperature range of 250-550℃ at a strain rate of 1x10/s, in 250-600℃ at 1x10^(-4)/s, and in 250-650℃ at 1x10^(-2)/s. The activation energies for each type of serration were about 0.57-0.74 times those for lattice diffusion indicating that a mechanism other than lattice diffusion is involved. It seems to be reasonable to infer that DSA is caused by the pipe diffusion of solute atoms through the dislocation core. Dynamic strain aging reduced the crack initiation and propagation life by way of multiple crack initiation, which comes from the DSA-induced inhomogeneity of deformation, and rapid crack propagation due to the DSA-induced hardening, respectively. (Received October 29, 2004)