和以及早年证明,奥氏体经回火后系在冷却过程中转变为马氏体。其转变点以M′来标示。指出,高速钢在一定的回火温度下,M′随回火的时间而改变,回火时间愈长,其M′愈高。Cohen等指出,经淬火的高速钢必须在一定温度经一定时间的回火,其奥氏体始经受催化作用,如: As well as the early years of proof, the austenite was tempered and transformed into martensite during cooling. The transition point is marked M ’. It is pointed out that M ’changes with the tempering time at a certain tempering temperature. The longer the tempering time is, the higher M’ is. Cohen pointed out that the quenched HSS must be tempered at a certain temperature for a certain period of time and its austenite undergoes a catalytic action such as: