Portevin–Le Chatelier Effects in a High-Mn Austenitic Steel

High-manganese austenitic steels were recently proposed to fabricate structural car body parts because of their very favorable combination of strength and ductility. They exhibit Portevin–Le Chatelier macroscopic plastic localization phenomena at the room temperature, as evidenced by the tensile curves first by the isolated stress peaks corresponding to the nucleation of deformation bands, which travel along the tensile axis, and then by serrations due to static deformation bands. The bands extend to the whole width of the specimen and cause a local temperature increase along with a slight surface relief. These plastic instabilities were studied during tensile tests at strain rates between 0.0004 and 0.04 s−1, with optical video recording, infrared thermography and optical extensometry, the latter based on digital image correlation. Two types of bands, type A and type C, were observed and are described.