Superior mechanical properties of 40Cr steel obtained by quenching and microstress relieving under electropulsing

High strength (the yield strength and ultimate tensile strength are 1920 ± 17 MPa and 2241 ± 39 MPa, respectively) and good ductility (15.2 ± 1.1%) are achieved simultaneously in 40Cr steel via electropulsing quenching (EQ) and tempering (ET). It was found that EQ contributes to ultra-fine martensite with high dislocation density and grain rotations (<110> texture distributed along the current direction and large Schmid factor). Meanwhile, ET is insufficient to modify the orientation, while it makes a rapid relief of micro residual stress without significantly decreasing the dislocation density. Compared to the conventional heat treatment, it provides a promising approach for enhancing the mechanical properties of steels in a short time.