Abstract: Die-pressurized water-cooling process was used to reduce the warpage distortion of 35CrMnSi steel disc during quenching, and the microstructure, distortion and hardness of the disc under different quenching temperatures and pressures were studied. The results show that the microstructure of the disc is lath martensite and a small amount of acicular martensite when quenching at 850 ℃ and 910 ℃ with pressure of 8 MPa, and no undissolved ferrite, Widmanstatten structure, reticulated ferrite and acicular ferrite are observed. The optimum heat treatment process is quenching at 890 ℃ with pressure of 10 MPa, under which the distortion is 11 μm and the hardness is 55 HRC. Due to the fact that the deformation of the disc in die-pressurized water-cooling process is well controlled and the distortion can meet the technical requirement, the pass rate of one-time inspection reaches 98%, and satisfactory application results is achieved

Key words: 35CrMnSi steel, disc, hardness, distortion, mold cooling