上海轨道交通1号线锦江乐园至莘庄路段P60钢轨使用至今已出现不同程度伤损。曲线路段的部分钢轨外轨内侧出现鱼鳞伤，严重的鱼鳞伤甚至向下发展导致核伤。鱼鳞伤在疲劳裂纹的初期发展缓慢，随着疲劳荷载次数增加，裂纹深度扩展速率dh/dN发生转折。定义裂纹深度扩展速率发生转折时对应的疲劳荷载的次数为鱼鳞伤萌生寿命。

he 60 rails on Shanghai Metro Line 1 from Jinjiang paradise station to Xinzhuang station have wounds of different degrees at the present time. Outer rails on curve railway have corner fine cracks on the inner flank, and some cracks evaluate down and lead to core wounds. Initially corner fine cracks expand slowly on the early stage, with the times of fatigue loads increasing crack depth expanding speed rate dh/dN breaks.The times of fatigue loads at turn over point is defined as the initial life of corner fine cracks.