Tailoring the residual stress and mechanical properties by electroshocking treatment in cold rolled M50 steel

Abstract

The residual stress and mechanical anisotropy caused by cold rolling (CR) seriously deteriorate the heat treatment distortion and final service performance of M50 steel. In this work, the effect of electroshocking treatment (EST) on the microstructure, residual stress and mechanical properties of cold rolled M50 steel has been investigated. The microstructure was characterized by X-ray diffraction (XRD), electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). The mechanical properties were measured by Vickers hardness, uniaxial tensile and Charpy impact test. The results show that the EST accelerates the movement and annihilation of dislocation and thus promotes the local recrystallization. The dislocation density of treated specimen decreases from 2.37 × 1015 m−2 to 1.96 × 1015 m−2 and the typical deformation texture is obviously weakened after EST treatment. It is also found that the residual stresses in the rolling and transverse direction of the EST specimens decrease by more than 50% with a more homogeneous distribution. In addition, the anisotropy of tensile strength and impact toughness decreases remarkably after EST treatment, which could be ascribed to the local rapid recrystallization and the weakened intensity of deformation texture. Furthermore, due to the release of concentrated stress, the average elongation of EST specimens is increased by 25.5% without loss of tensile strength.