Study on Pre-hardening Process of P20 Steel

The pre-hardening process of plastic mould steel P20 was studied by quenching and tempering tests.Two methods for calculating the pre-hardening hardness were developed.The results show that the tempering temperature and time are the main effect factors on hardness,and quenching temperature has a little effect.The optimal pre-hardening process is quenching at 860 ℃for 2 h and tempering at 660 ℃ for(0.5～10) h.