Numerical Simulation and Experiment on Quenching Process of P20 Die Steel with New Online Pre-Hardening Equipment

A new online pre-hardening (OPH) equipment for quenching die steel has been developed by University of Science and Technology Beijing (USTB) and Dongbei Special Steel Group in Dalian Special Steel Co., LTD. OPH equipment consists of strong cooling water jet, medium cooling water jet, weak cooling water jet, air-water spray, and side water jet and has flexible cooling and control ability. Based on the equipment, online quenching process of AISI P20 (3Cr2Mo) die steel was performed by numerical simulation and production experiment. The result of temperature field by numerical simulation agrees well with experiment result, which can prove that numerical simulation can be a very good guidance for production experiment. Experimental tempering metallographic structure of the whole P20 plate is tempered troostite and the tempering hardness difference of P20 die steel can be controlled within 3 HRC in the whole plate under quenching process by numerical simulation. The prediction technology of numerical simulation can meet the different cooling rate control and make quenching process comply with preset quenching route to guarantee material microstructure and performance.