Abstract: Effect of isothermal quenching temperature during quenching and partitioning (Q-P) process on microstructure and mechanical properties of 60Mn2SiCr steel was studied by means of scanning electron microscope, X-ray diffractometer, impact testing machine, Rockwell hardness tester and tensile testing machine. The relationship between the retained austenite content in the microstructure and the carbon content in the retained austenite of the tested steel after Q-P treatment and the mechanical properties was emphatically analyzed. The results show that when the isothermal quenching temperature increases from 120 ℃ to 180 ℃, the Rockwell hardness, impact absorbed energy, tensile strength and elongation of the specimen decrease with the decrease of content of martensite and retained austenite and carbon content in retained austenite. When the isothermal quenching temperature in Q-P process is 120 ℃, the mechanical properties are optimal, with volume fraction of retained austenite of 13.9%, the carbon content (mass fraction) in the retained austenite of 1.1%, the Rockwell hardness of 58.8 HRC, the impact absorbed energy of 50.7 J, the tensile strength of 1768 MPa and the elongation of 19.6%.

Key words: Q-P process, 60Mn2SiCr steel, isothermal quenching temperature, microstructure, properties