某汽车悬架弹簧在质量测试过程中发生断裂。通过宏观检查、化学成分分析、断口分析、金相检验、残余应力测试、硬度测试和耐久性测试等方法对弹簧断裂的原因进行了分析。结果表明：弹簧钢丝在冷卷工序时与刀具接触过紧，两者剧烈摩擦后生热，引起弹簧组织变形而形成硬而脆的白亮层，在冲击载荷的不断作用下，白亮层先产生裂纹，并最终导致弹簧断裂。

The automotive suspension spring was fractured during the quality test. The causes of spring fracture were analyzed by means of macro examination, chemical composition analysis, fracture analysis, metallographic examination, residual stress test, hardness test and durability test. The results show that the spring steel wire and cutter contacted too tightly in cold rolling process, and the heat was generated after the sharp friction, which caused spring tissue deformation and formed a hard and brittle white bright layer. Under the continuous impact loads, the white bright layer first produced cracks, which eventually led to the spring fracture.