淬火温度对2200 MPa级超高强度钢力学性能与微观组织的影响

采用力学性能测试、光学显微镜(OM)、透射电镜(TEM)、X射线衍射(XRD)等材料分析方法研究了淬火温度对2200 MPa级超高强度钢的力学性能及微观组织的影响。结果表明,试验钢最佳淬火温度为1025 ℃,再经后续热处理能获得最佳的强韧性匹配,此时抗拉强度为2244 MPa,屈服强度为1836 MPa,U型缺口冲击吸收能量为59 J,断裂韧性为57.7 MPa·m^1/2。淬火温度较低时,出现粗大一次碳化物富Mo型M₆C碳化物,严重影响强度和韧性。随着淬火温度升高,一次碳化物逐渐减少,直至1000 ℃完全消失,当淬火温度高于1025 ℃时晶粒显著粗化,晶粒尺寸成为主要的负面影响因素。

Effect of quenching temperature on mechanical properties and microstructure of 2200 MPa ultra-high strength steel

Effect of quenching temperature on the mechanical properties and microstructure of 2200 MPa ultra-high strength steel was studied by means of mechanical properties test,optical microscope(OM),transmission electron microscope(TEM),X-ray diffraction(XRD)and other analysis methods.The results show that the optimal quenching temperature of the tested steel is 1025℃,so the subsequent heat treatment can obtain the best strength and toughness match:the tensile strength is 2244 MPa,the yield strength is 1836 MPa,the U-notch impact absorbed energy is 59 J,and the fracture toughness is 57.7 MPa·m^1/2.When the quenching temperature is low,coarse primary carbides appear in Mo-rich M₆C carbides,which seriously affect strength and toughness.As the quenching temperature increases,the primary carbide gradually decreases until it completely disappears at 1000℃.When the quenching temperature is higher than 1025℃,the grains are significantly coarsened,and the grain size becomes the main negative influencing factor.