Plastic strain localization in stainless steel

Abstract

This work reports the study of macroscopic strain localization in austenite stainless steel AISI 321. The evolution of macroscopically localized plastic strain at different stages of strain hardening was visualized via a digital image speckle (DIC) correlation method. The stress-strain curves of steels exhibit the linear work hardening and jerky flow as the main stages of strain hardening. The analysis of local strain distributions reveals that linear work hardening is characterized by a mobile system of plastic strain localization centers arranged at equal distances. Unlike the linear hardening, jerky flow possesses the propagation of four single plastic strain fronts that occur one after another through the sample due to the y-α′ phase transition and the Portevin–Le Chatelier (PLC) effect. No merged strain localization centers that would lead to the neck formation are found at the jerky flow stage preceding the sample failure.