变形及冷速对预硬化塑料模具钢P20组织与性能的影响

Effect of deformation and cooling rate on microstructure and mechanical properties of P20 pre-hardened plastic mould steel

采用Gleeble-1500热模拟试验机研究了预硬化塑料模具钢P20的在线淬火工艺,分析了不同变形量及冷却工艺条件下P20钢的显微组织及力学性能。结果表明:增大P20钢奥氏体未再结晶区变形量将会显著促进铁素体转变,抑制贝氏体转变,对马氏体相变影响不大;随着冷速的增大,P20钢的硬度先增加,后趋于不变,当冷速为1～3℃/s时,硬度值稳定在53.1～56.2 HRC,硬度差约为3 HRC。P20钢在线淬火时,其冷速需控制在大于1℃/s,以满足其回火后截面硬度均匀要求。

The on line quenching test was carried out on P20 pre hardened plastic mould steel by Gleeble 1500 thermal mechanical simulator.Meanwhile,the microstructure and mechanical properties of P20 steel were analyzed under different deformation and cooling rates.The results show that with increasing the austenite deformation,the transformation of ferrite is promoted,the bainite is restrained but the martensite is little affected;with increasing the cooling rate,the hardness of P20 steel is enhanced at first,then becomes constant.When the cooling rate is 1-3 ℃/s,the hardness keeps in the range of 53.1-56.2 HRC and the difference of hardness is about 3 HRC.So in on line quenching process,the cooling rate of P20 steel should be controlled more than 1 ℃/s to satisfy the demand of uniform hardness in cross section.