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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0.113~0.284μm,淬火轨片间距为0.076~0.148μm。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。
In order to further understand the relationship and mechanism of the effect of on-line afterheat quenching on the microstructure and properties of the rail, the whole cross-section of the hot rolled and in-line quenched steel was observed by scanning electron microscopy. Vickers hardness tester and tensile test The effects of on-line afterheat quenching on the mechanical properties of the rail were analyzed. The results show that the microstructures of on-line residual hot-quenched and hot-rolled rails are all lamellar pearlite, but the pitches of quenched pearlite are obviously smaller. The distance between hot-rolled pearlite sheets is 0.113 ~ 0.284μm, Rail spacing of 0.076 ~ 0.148μm. The micro-hardness of hot-rolled rail has no obvious difference in the whole cross-section, and the microhardness of in-line residual heat hardened rail is generally higher than that of hot-rolled rail. On-line residual heat quenching can effectively improve the performance of U75V rail. After heat treatment, the tensile strength and elongation of rail increase by 16.6% and 20% respectively compared with that of hot rolling, which effectively improves the serviceability of rail.