Activation energy for serrated flow in type 316L(N) austenitic stainless steel

Abstract

Tensile tests were performed at a wide range of strain rates (3.16×10−5−3.16×10−3s−1) and temperatures (300–1123K) to examine serrated flow behaviour, an important manifestation of dynamic strain ageing (DSA), in type 316L(N) austenitic stainless steel. The steel exhibited distinct low and high temperature serrated flow regimes separated by a retardation bay. Based on the activation energy value of 115kJmol−1, diffusion of interstitial carbon has been suggested to be responsible for serrated flow in the low temperature regime. In the high temperature regime, an average activation energy value of 206kJmol−1 obtained using different methods indicated that diffusion of substitutional chromium atom is responsible for DSA. Disappearance of serrations at high temperatures has been ascribed to the effects associated with precipitation reaction between chromium and carbon atoms. The influence of nitrogen retarding DSA in type 316L(N) stainless steel has been discussed.