回火工艺对W6Mo5Cr4V2钢冷冲模组织和使用寿命的影响

在低温淬火条件下，比较了常规高温回火（三次），中温回火（一次） 高温回火（二次）以及低温回火（二次）等3种不同回火工艺对W6Mo5Cr4V2高速钢冷冲模的组织和性能的影响，结果表明，低温回火为最佳工艺，此时钢的硬度虽然偏低（约61HRC），但冷却模在对弹簧钢板冲孔时的使用寿命却最长。X射线衍射分析发现，低温回火后的W6Mo5Cr4V2高速钢中含有较多残留奥氏体（约15.8%），它们在一定程度上可提高钢的韧性，阻碍冲击载荷下裂纹的形核与扩展，这是低温回火的W6Mo5Cr4V2高速钢冷却模使用寿命提高的主要原因。

Influence of Tempering Process on Microstructure and Service Life of the Cold-Punching Die Made of W6Mo5Cr4V2 High Speed Steel

Under the lower temperature quenching condition,three different temper processes,which are normal high temperature tempering,medium then high temperature tempering,and low temperature tempering,were performed to investigate their influences on the service life of cold punching die made of W6Mo5Cr4V2 high speed steel for punching hole on the spring steel plates.The hardness and microstructure were examined and the amounts of residual austenite (A R) in the steel were determined by XRD.It was found that the low temperature tempering is the best one among the three tempering processes which makes the cold punching die have a slightly lower hardness about 61HRC but have a longer service life.This is mainly attributed to the fact that there is more amounts of A R (about 15 8%) in the low temperature tempered one which would be beneficial to the increase of the toughness in a certain extent and hinder the crack nucleation and growth when the impact force acts.