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对朔黄铁路的5段75 kg.m-1的U75V钢轨性能进行检验,分析伤损钢轨裂纹附近的性能。分析表明:U75V热轧钢轨母材的组织和硬度均合格,但U75V热处理钢轨的淬火层深度及横断面硬度均未满足TB/T 2635—2004的要求;显微硬度数据显示,在钢轨横断面存在较薄的硬化层;曲线下股钢轨踏面中心裂纹的深度在1.3 mm左右,并呈现不同程度的剥离掉块,与钢轨硬度分布特征有关;裂纹萌生于钢轨轨头表面塑性流变层内,裂纹起始的发展与列车运行方向成一定的锐角,出流变层后基本以垂直方向朝轨头内部扩展,到一定程度后,裂纹呈鱼钩状,以大致与列车运行的相反方向朝轨顶面扩展,最终导致剥离掉块。建议使用符合标准的热处理钢轨;对曲线钢轨及时进行大机打磨;采取措施,降低纵横向蠕滑力。
The performance of the 75mm.m-1 U75V rail of 5 sections of Shuo-Huang-Huang railway was tested to analyze the performance of the rail near the damaged rail. The results show that both the microstructure and hardness of the U75V hot rolled rail base metal are qualified, but the depth and cross-section hardness of the quenched layer of the U75V heat-treated rail do not meet the requirements of TB / T 2635-2004. The microhardness data show that in the rail cross section There is a thin layer of hardened layer. The depth of the center crack on the tread surface is about 1.3 mm under the curve, and the peeling occurs in different degree, which is related to the hardness distribution of the rail. The crack initiation occurs in the plastic rheological layer on the rail head surface, The initiation of crack initiation is at an acute angle to the running direction of the train. After the run-off deformation occurs, the crack propagates toward the interior of the rail head in a vertical direction. To a certain extent, the crack presents a hook-like shape and runs approximately in the opposite direction of the running of the train The top extension eventually leads to peeling off the block. It is recommended to use the heat-treated rails that meet the standards; to timely conduct large-scale grinding on the curved rails; and to take measures to reduce the vertical and horizontal creep forces.