Effect of deformation path on the microstructure and mechanical behavior of TWIP980 steel

Abstract

Recent technological advances have made it possible to manufacture steels with both high strength and high ductility. This is the case for Twinning-Induced Plasticity (TWIP) steels which are characterized by a twinning deformation mechanism, which is responsible for its excellent properties. In this work, TWIP980 steel was tested under tensile loading along the rolling direction until pre-deformations of 10%, 20%, and 30% were reached. In order to assess the effect of the deformation path, the pre-deformed samples were reloaded in directions of 0◦, 45◦ and 90◦ against the rolling direction. Microstructural analysis was performed by means of optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The yield stress increased with the imposed deformation for all the tested directions. As the strain path changed from 0◦ to 90◦, the yield stress for reload decreased, and the Bauschinger effect and permanent softening was observed. The yield plateau was observed as being directly influenced by deformation path without influence by strain rate and temperature.