全长淬火钢轨踏面伤损及横向疲劳断裂分析

对实际伤损钢轨的宏微观形貌、金相、硬度以及探伤等检验分析,确定轨头踏面下4mm～6mm区域存在纵向水平疲劳裂纹是产生全长淬火钢轨伤损的原因。检验分析表明,在轮轨接触剪应力作用下,由于淬硬层区域存在金相组织、硬度过渡不均匀等淬火缺陷,导致轨头内部纵向水平疲劳裂纹萌生和扩展,引起钢轨伤损;在分析基础上,提出预防和改进措施。

Analysis of Tread Failure and Transverse Fatigue Fracture of Full-length Quenched Rail

Through measurement and analysis of the macro and micro appearances, the metallography, hardness and ultrasonic inspection of the defected rail, the paper determines that the reason of the rail failure is the (longitudinal) and horizontal fatigue crack existing at a depth of 4 mm to 6 mm beneath the tread. The test and analysis shows that under the action of the wheel/rail contact shear stress, the quenched area has quenching (defects) such as metallography and uneven hardness transition, which leads to the initiation and propagation of the internal longitudinal and horizontal fatigue crack in the rail head, and that results in the rail damage. Based upon the analysis, the paper provides measures for prevention and improvement.