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The Structural Formation in Differentially-Hardened 100-Meter-Long Rails during Long-Term Operation
Steel in Translation Pub Date : 2020-02-01 , DOI: 10.3103/s0967091220020047
V. E. Kormyshev , E. V. Polevoi , A. A. Yur’ev , V. E. Gromov , Yu. F. Ivanov

Abstract By using modern physical-materials science methods, the roll surface of structural-phase states and mechanical properties has been analyzed at a distance ranging from 0 to 22 mm with respect to the central axis and to the fillet of differentially-quenched DT 350 grade 100-meter-long rails. These rails have been manufactured at Evraz United West Siberian Metallurgical Plant after long-term operation on an experimental test ring (passed gross tonnage amounting to 1411 million tons). According to chemical composition, the rail metal satisfies the requirements of TU (Engineering Specifications) 0921-276–01124323–2012 for steel E76HF grade steel. The impact strength and hardness on the head’s roll surface and throughout the cross section meet the TU (Engineering Specifications) requirements. The microstructure of the rail metal is represented by finely dispersed lamellar pearlite—1.5 points of scale No. 7 according to GOST (State Standard) 8233—with inclusions of excess ferrite along the grain boundaries. The interlamellar distance in the railhead ranges from 0.10 to 0.15 μm. The long-term operation of the rails is accompanied by the formation of a gradient structure presented by a regular change in hardness, microhardness, and impact strength throughout the railhead section. The microhardness at a depth of 2 mm counted from the roll surface amounts to 1481–1486 MPa. At a depth of 10 mm, the microhardness decreases to 1210–1385 MPa, which is caused by an increase in the interlamellar distance and by a decrease in the level of metal cold-work strengthening in the course of long-term operation. It has been suggested that this could be caused by an increase in the interlamellar distance and by a decrease in the level of cold-work strengthening in the course of long-term operation.

中文翻译:

不同硬化100米长钢轨长期运行过程中的结构形成

摘要 采用现代物理-材料科学方法,在相对于中心轴和差速淬火 DT 350 级圆角的距离范围为 0 到 22 mm 处,分析了轧辊表面的结构相状态和力学性能。 100米长的铁轨。这些钢轨是在 Evraz United West Siberian Metallurgical Plant 在实验测试环上长期运行后制造的(通过总吨位达 14.11 亿吨)。根据化学成分,钢轨金属满足 TU(工程规范)0921-276-01124323-2012 对 E76HF 级钢的要求。机头辊面和整个横截面的冲击强度和硬度满足TU(工程规范)要求。铁轨金属的微观结构由精细分散的层状珠光体(根据 GOST(国家标准)8233 标度为 7 级的 1.5 个点)表示,其中包含沿晶界的过量铁素体。轨头中的层间距离范围为 0.10 至 0.15 μm。钢轨的长期运行伴随着梯度结构的形成,表现为整个轨头部分的硬度、显微硬度和冲击强度有规律的变化。从轧辊表面算起 2 mm 深度处的显微硬度为 1481-1486 MPa。在 10 mm 深度处,显微硬度下降至 1210-1385 MPa,这是由于长期运行过程中层间距离增加和金属冷加工强化水平下降所致。
更新日期:2020-02-01
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