Effect of Electrical Pulse Quenching and Tempering Treatment on Microstructure and Mechanical Properties of 35CrMo Steel for Gear Sleeve

Hot rolled 35CrMo steel was treated by traditional quenching+traditional tempering, electrical pulse quenching+traditional tempering and traditional quenching+electrical pulse tempering at different tempering temperatures (550-640℃) and for different pulse times (1,2 times) and pulse duration (60-180 ms). The microstructures and mechanical properties after treatment were studied and compared. The results show that after electrical pulse quenching+traditional tempering at 550℃, traditional quenching+single electrical pulse tempering, and traditional quenching+two electrical pulse of 60 ms tempering treatment, the microstructures of the test steel were all similar to that after traditional quenching+traditional tempering; all were composed of martensite and carbides. With increasing tempering temperature, lamellar sorbite appeared in the structure after electrical pulse quenching+traditional tempering; the tensile strength and hardness of the test steel decreased, and the elongation increased. The electrical pulse quenching or tempering could improve the strength-ductility balance of the test steel, and the strength-ductility balance was the best after the electrical pulse quenching +traditional tempering at 580℃.