在线余热淬火对U75V钢轨组织性能的影响

 为进一步掌握在线余热淬火处理对钢轨组织性能的影响关系和机理，采用扫描电镜对热轧态钢轨和在线余热淬火处理后的钢轨进行了全断面的组织观察，利用维氏硬度仪和拉伸试验机对比分析了在线余热淬火对钢轨力学性能的影响。结果表明，在线余热淬火和热轧态钢轨全断面的组织全部为片层状珠光体组织，但淬火轨珠光体片间距明显较小，热轧态钢轨珠光体片间距为0.113~0.284 μm，淬火轨片间距为0.076~0.148 μm。热轧态钢轨全断面显微硬度相差不大，在线余热淬火钢轨显微硬度普遍较热轧态钢轨高。在线余热淬火可以有效提高U75V钢轨性能，热处理后钢轨抗拉强度和伸长率分别较热轧态提高16.6%和20%，有效改善了钢轨的使用性能。

Effect of Online Slacking-Quench on the Microstructure and Properties of U75V Rail

In order to further get the effects and mechanisms of the online slacking-quench on microstructures and mechanical properties of U75V rail, the microstructures of the whole section of the hot rolled and slacking-quench on line rail was observed using scanning electronic microscope, and the effect of on-line slacking-quench on the mechanical properties of U75V rail was compared and analyzed using Vicker’s indentation test machine and tensile testing machine. The results show that the microstructure of the whole section of the rail was lamellae pearlite in both on-line slacking-quench and hot rolling; but the pearlite interlamellar spacing after online slacking-quench was distinctly refined. The pearlite interlamellar spacing of the hot rolled rail was about 0.113 μm to 0.284 μm, while that of the slacking-quench rail was about 0.076 μm to 0.148 μm. The microhardness of the whole section of the hot rolled rail had little difference, while the slacking-quench rail microhardness was much higher. Moreover, the mechanical properties of U75V rail had been improved effectively by on-line slacking-quench; and the rail tensile strength and elongation increased by 16.6% and 20% compared that of hot-rolled rail, respectively.