采用化学成分分析、金相检验及生产现场检测等方法对某批模锻连杆在喷丸过程中出现断裂的原因进行了分析。结果表明，连杆的锻造温度偏高，在未经正火处理就直接进行调质处理，其中淬火保温时间不够，连杆心部仍保留原始的锻造组织，造成连杆边缘和心部的组织内外应力差异增大，导致在冷却过程中产生裂纹。由此说明连杆在喷丸前已存在裂纹。

This paper has analyzed the causation of the links′ breaking during the sand blasting process. While,the fracture analysis indicates that the links have cracked before the sand blasting process. On the base of chemical analysis and metallographic inspection,and colligating the heat-treatment locale′s examination,the paper elicits this conclusion: too high forging temperature,being empty of normalizing treatment,time shortage of heat preservation during the quenching process,these factors deduced the extreme internal stress during the cooling process of quenching treatment,and the extreme internal stress lead the links′ cracking.