07MnCrMoVR水电钢的生产工艺及组织性能

Production process and microstructure and properties of 07MnCrMoVR hydropower steel

采用激光共聚焦扫描显微镜对07MnCrMoR水电钢奥氏体晶粒长大的动态过程进行了原位观察,并对其静态CCT曲线进行了测定,利用淬火机和热处理炉对38 mm厚的试验钢进行了淬火和回火试验。结果表明:试验钢在1200℃以下加热时奥氏体晶粒长大趋势不明显;当冷却速率为0.05~0.25℃/s时,试验钢的组织转变为多边形铁素体+珠光体,冷却速率为0.5~20℃/s时转变为贝氏体组织,冷却速率为20~50℃/s时转变为马氏体组织;930℃淬火后,试验钢的组织转变为板条贝氏体+马氏体,600℃回火后转变为铁素体+回火贝氏体,大量的碳化物在铁素体基体上析出,其屈服强度为602 MPa,抗拉强度为713 MPa,-20℃低温冲击吸收能量为259 J,力学性能高于国家标准的要求,为最佳的调质生产工艺。

The dynamic process of austenite grain growth of 07 MnCrMoR hydropower steel was observed in situ by using a laser confocal scanning electron microscopy,and the static CCT curves were measured.The quenching and tempering test of 38 mm thick tested steel was carried out by quenching machine and heat treatment furnace.The results show that the growth tendency of the austenite grain is not obvious when the 07 MnCrMo steel is heated below 1200℃.When the cooling rate is 0.05-0.25℃/s,the microstructure of the 07 MnCrMo steel is polygonal ferrite and pearlite,when the cooling rate is 0.5-20℃/s,the microstructure is bainite,when the cooling rate is 20-50℃/s,the microstructure is martensite.After quenching at 930℃,the microstructure of the 07 MnCrMo steel is lath bainite and martensite,the microstructure is ferrite and tempered bainite after tempering at 600℃,and a large amount of carbides are precipitated on the ferrite matrix,the yield strength of the 07 MnCrMo steel is 602 MPa,the tensile strength is 713 MPa,the low-temperature impact absorbed energy at-20℃is 259 J,the mechanical property is higher than the requirement of the national standard,which indicates this heat treatment process is the optimum quenching and tempering process of the 07 MnCrMo steel.