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某异型钢轨在经60kg/m热轧钢轨加工至50kg/m过渡轨后出现矫直断裂。经对钢轨断口的宏、微观检验和分析,认为,断裂裂纹起源于轨腰次表层;钢轨发生矫直断裂的原因是在加工异型钢轨的过程中,加热温度偏高,导致轨腰表层部分区域出现沿晶氧化,锻压时因轨腰表层受拉应力作用,沿晶氧化处形成微裂纹,随后矫直时轨腰三点弯曲受力,微裂纹缺陷处产生应力集中致使裂纹扩展,导致钢轨断裂。
A shaped rail after 60kg / m hot-rolled rail to 50kg / m transitional rail after straightening fracture. The macroscopic and microscopic examination and analysis of the rail fracture indicate that the fracture cracks originate from the subsurface of the rail waist. The reason for the straightening fracture of the rail is that the heating temperature is high during the process of forming the special-shaped rail, When oxidation and forging occurs, the micro-cracks are formed along the crystal oxidation due to the tensile stress on the surface of the rail and waist during forging, and then the three-point bending of the rail waist is strained during straightening. The stress concentration at the micro-crack defects causes the cracks to rupture .