Abstract: Change rule the microstructure evolution and mechanical properties of 55NiCrMoV7 die steel under different quenching temperature (790~910°C) , and tempering temperature (100 ~650°C ) are studied by means of scanning electron microscopy (SEM) , hardness test, V-impact test, uniaxial tensile test combined with finite element modeling and simulation. The results show that, with the increase of quenching temperature, spherical caibide gradually dissolves into martensite matrix, martensite structure grows and coarsens, and residual austenite increases gradually； after quenching, the HRC hardness value is basically stable at 42 ~ 46, and the yield and tensile strength first increase and then decrease, reaching a maximum of 1380 MPa and 1485 MPa after quenching at 870 °C ,and the maximum value of impact toughness is 26 J after quenching at 850 °C. In different temperature tempering process, the content of martensite structure basically stable, with the increase o£ tempering temperature, the retained austenite gradually disappears, fine and dispersed carbides begin to precipitate at the boundary of martensite. Quenching at 870°C 4 h and tempering at 560°C 6 h can make 55NiCrMoV7 steel to have good comprehensive mechanical properties.

摘要： 采用扫描电镜(SEM)、硬度测试、V型冲击实验和单向拉伸实验结合有限元建模仿真,研究了55NiCrMoV7模具钢在不同淬火温度(790～910℃)、回火温度(100～650 ℃)下的微观组织演化和力学性能的变化规律。结果表明,随着淬火温度升高,球状碳化物逐渐溶解到马氏体基体中,马氏体组织不断长大、粗化,残余奥氏体逐渐增多;淬火后HRC硬度值基本稳定在42～46,屈服强度和抗拉强度先增大后减小,870 ℃淬火后均达到最大值1 380 MPa和1485 MPa,冲击韧性在850 ℃淬火后最大,为26 J。在不同温度回火过程中,马氏体组织含量基本稳定,随着回火温度继续升高,残余奥氏体逐渐溶解,碳化物从马氏体边界处析出,细小而弥散。870 ℃ 4 h淬火+560 ℃ 6 h回火可以使55NiCrMoV7钢具有良好的综合力学性能。

关键词: 55NiCrMoV7钢, 微观组织, 力学性能, 模型