回火温度对DQ工艺1000 MPa级高强钢组织及性能的影响

Effect of tempering temperature on microstructure and properties of 1000 MPa high strength steel produced by DQ process

采用OM、SEM、TEM研究了1000 MPa级高强钢在直接淬火条件下550~670℃范围内回火后的组织和性能。结果表明,在550℃至610℃之间回火时,马氏体板条开始回复,碳化物析出,试验钢组织以回火马氏体为主;在640℃至670℃之间回火时,马氏体板条开始发生再结晶,碳化物逐渐长大,试验钢组织以回火索氏体为主。采用DQ-T工艺生产1000 MPa级高强钢的最佳回火温度区间为610~640℃,此时规定塑性延伸强度为1012~1053 MPa,抗拉强度为1045~1092 MPa,塑性冲击吸收能量为38~39 J,伸长率为17%~19%,断面收缩率为40%~42%,有较好的综合力学性能。

Microstructure and properties of 1000 MPa high strength steel tempered in the temperature range of 550-670℃under direct quenching were studied by OM,SEM and TEM.The results show that when tempered between 550℃and 610℃,martensite lathes begin to recover and carbides precipitate,the microstructure of the tested steel are mainly tempered martensite;when tempered between 640℃and 670℃,the martensite laths begin to recrystallize and the carbides grow up gradually,the microstructure of the tested steel is mainly tempered sorbite.The optimum tempering temperature range for the 1000 MPa high strength steel produced by DQ-T process is 610-640℃.The proof strength is 1012-1053 MPa,the tensile strength is 1045-1092 MPa,the plastic impact absorbed energy is 38-39 J,the elongation is 17%-19%,the percenttage reduction of area is 40%-42%,and the comprehensive mechanical properties are good.