淬火温度对高铁车轴用钢组织及性能的影响

Effect of quenching temperature on microstructure and properties of high-speed axle steel

利用扫描电镜(SEM)和透射电镜(TEM)研究了淬火温度对高铁车轴用钢显微组织和力学性能的影响。结果表明:随着淬火温度的升高,抗拉强度和规定塑性延伸强度先快速增大后缓慢减小,塑性变化不明显,冲击吸收能量持续下降,同时试验钢原始奥氏体晶粒长大,马氏体板条束(Packet)长大,淬火温度升高到900℃后晶粒迅速粗化,后续回火碳化物有所细化。在淬火温度为850℃时(675℃回火)试验钢具有最佳的综合性能:抗拉强度为796 MPa,规定塑性延伸强度为677 MPa,伸长率为24.5%, 25℃和-40℃的冲击吸收能量(A_(KU2),5 mm缺口)分别为82 J和72 J。

The effects of quenching temperature on microstructure and mechanical properties of high-speed axle steel were studied by means of scanning electron microscopy (SEM)and transmission electron microscopy (TEM).The results show that with the increase of quenching temperature,the tensile strength and the specified plastic elongation strength of the steel first increase rapidly and then decrease slowly,the plasticity doesn't change a lot,and the impact absorbed energy decreases continuously,while the primary austenite grain of the steel and martensite lath (Packet)grows.When the quenching temperature increases to 900 ℃ ,the grain is coarsened rapidly,and the subsequent tempering carbides are refined.The experimental steel has the best comprehensive properties after quenching at 850℃ and tempering at 675℃ ,which is that the tensile strength is 796 MPa,the specified plastic elongation strength is 677 MPa,the elongation is 24.5%,and the impact absorbed energy (AKU2,5 mm notch)at 25℃ and -40℃ is 82 J and 72 J,respectively.