客运专线钢轨踏面掉块原因分析

Cause Analysis of Shelling on Rail Tread of Passenger Dedicated Line

某客运专线钢轨在上道使用近10年后,多处钢轨踏面部位出现局部裂纹及掉块伤损。对钢轨的伤损特征、伤损宏观微观形貌、金相组织进行了检测分析,并对钢轨进行了化学成分分析和力学性能评价。结果表明:钢轨的伤损类型属于轨头踏面斜线状剥离裂纹伤损(又称踏面隐伤),为钢轨滚动接触疲劳中的主要伤损形式之一。裂纹起源于轨头表面,初始时沿金属形变流线方向以一定角度向深处扩展,扩展到约5 mm深度时,裂纹转向水平扩展,后续形成掉块,严重时也可能继续斜向扩展形成横向疲劳断裂。科学合理地进行钢轨预防性打磨和矫正性打磨,可以防止或减缓此类伤损的形成和发展。

The partial shelling damages occurred on rail tread of passenger dedicated line after about ten years of service.The damage feature,macroscopic morphology and metallographic structure of the damaged rail were tested.The chemical composition and the mechanical properties of the rail were inspected.The results showed that the damage type belonged to oblique head checking damage of rail tread(also known as tread squat),which is one of the main damage forms of rail rolling contact fatigue.The crack originated from the rail head surface and initially extended to the depth in a certain angle along the direction of the metal deformation streamline.When it extended to a depth of about 5 mm,the crack turned to horizontal propagation and subsequently forms a shelling.In serious cases,it may continue to extend obliquely to form a transverse fatigue fracture.Scientific and reasonable rail preventive grinding and corrective grinding can prevent or slow down the formation and development of such damage.