一种细晶粒超高强韧性的高速车轴钢,所述钢的化学成分以重量百分比计为,C：0.24～0.32％、Si：0.20～0.40％、Cr：0.60～1.00％、Mn：0.40～0.70％、V：0.08～0.13％、Nb：0.02～0.10％、Ni：2.70～3.30％、Mo：0.40～0.60％、Alt：0.010～0.040％、P：<0.010％、S：<0.010％、O：<0.0015％、N：<0.008％,其余为Fe和不可避免的杂质；同时本发明还提供所述钢的热处理方法。本发明充分发挥各元素在车轴钢中的作用,并采用两次淬火+高温回火热处理,最终使高速车轴具有良好的抗冲击、抗疲劳等服役性能、优异的强韧性匹配和良好的淬透性。本发明所车轴钢的组织中奥氏体晶粒的平均晶粒尺寸为10-13μm,屈服强度Rp0.2≥900MPa,抗拉强度Rm≥950MPa,延伸率A≥15％,5mm缺口室温纵向冲击吸收功KU2≥100J,韧脆转变温度低于-80℃。

The chemical composition of the steel by weight percentage is C: 0.24 ~ 0.32%, Si: 0.20 ~ 0.40%, Cr: 0.60 ~ 1.00%, Mn: 0.40 ~ 0.70%, V: 0.08 ~ 0.13%, Nb: 0.02 ~ 0.10%, Ni: 2.70 ~ 3.30%, Mo: 0.40 ~ 0.60%, Alt: 0.010 ~ 0.040%, P: < 0.010%, S: < 0.010%, O: < 0.0015%, N: < 0.008%, the rest is Fe and inevitable impurities; The invention also provides a heat treatment method for the steel. The invention gives full play to the role of each element in axle steel, and adopts double quenching + high temperature tempering heat treatment to finally make high-speed axle have good impact resistance, fatigue resistance and other service performance, excellent matching of strength and toughness and good hardenability. The average austenite grain size in the structure of the axle steel of the invention is 10-13μm, yield strength Rp0.2≥900MPa, tensile strength Rm≥950MPa, elongation A≥ 15%,5mm notch longitudinal impact absorption work KU2≥100J at room temperature, and ductile-brittle transition temperature below -80℃.