42CrMoA滚丝轴端部开裂分析

Cracking analysis of 42CrMoA roller shaft end

对42CrMoA滚丝轴零件端部开裂缺陷进行了宏观、化学成分和微观失效分析,失效分析表明,滚丝轴开裂源为原材料原始端部裂纹;过程调查和讨论分析确定原材料原始端部裂纹的产生工序为砂轮磨切锯冷切过程中形成的锯切裂纹。锯切裂纹的产生原因主要为钢材冷却应力及锯切热应力的综合作用,通过采取对钢材退火及坑冷缓冷的办法可防止锯切裂纹的出现。

The macroscopic examination,chemical composition and micro failure analysis were conducted for the cracking defect of the end of 42CrMoA roller shaft.The failure analysis showed that the cracking source of the roller shaft was the original end crack of the raw material.The process investigation and discussion analysis confirmed that the original end crack of raw materials was the sawing crack formed in the cold cutting process of grinding wheel saw.The main cause of sawing cracks was the combined effect of steel cooling stress and sawing thermal stress.The occurrence of sawing cracks could be prevented by annealing the steel and cooling slowly in pits.