某45钢偏心轴在加工过程的不同阶段均发现裂纹,采用金相检验、化学成分分析和断口分析等方法对裂纹产生的原因进行了分析。结果表明：偏心轴原材料塔形件、偏心轴调质件和高频淬火处理件的表面裂纹性质都相同;原材料中含有较多大尺寸的非金属夹杂物是导致该偏心轴表面形成裂纹的主要原因。

45 steel eccentric axes cracked during different period of the machining process. By adopting metallographic examination,chemical compositions analysis and SEM fracture analysis,cracking reason for the eccentric axes was studied. The results show that cracking characteristic of the raw material turriform part,thermal refining eccentric axis and high frequency hardening eccentric axis were all the same. Many big size non-metallic inclusions in the raw material were the main reason for the cracking of the 45 steel eccentric axes.