采用欠速淬火工艺对再用轨进行全长热处理，对经过热处理后的再用轨和普通再用轨的力学性能如冲击韧性、断裂韧性、疲劳强度、残余应力、硬度及金相组织等进行了对比实验，结果表明，经过欠速淬火后，再用轨的强韧性和塑性有明显提高，并结合铺设实验，探讨了欠速淬火提高钢轨强韧性能的原因以及它与使用性能的关系． The use of under-speed quenching process for re-use rail full-length heat treatment, heat treatment after the re-use rail and the general re-use rail mechanical properties such as impact toughness, fracture toughness, fatigue strength, residual stress, hardness and microstructure The experimental results show that the toughness and plasticity of reused rails increase obviously after under - speed quenching, and the reasons for the under - speed quenching to improve the toughness of rails and the relationship between them and serviceability are also discussed.