调整螺母在调质处理后探伤时发现有裂纹, 采用宏观检验、化学成分分析、金相检验等方法对其开裂原因进行了分析。结果表明: 该批调整螺母开裂是由于明显的带状偏析和较多的夹杂物引起的淬火裂纹, 同时由于回火温度过高, 使得裂纹两侧脱碳出现网状铁素体。

Cracks were found inside the adjusting nuts when testing after quenching and tempering treatment, and by means of macroscopic examination, chemical compositions analysis and metallographic examination, the cracking reason was analyzed. The results show that the cracks of the adjusting nuts were quenching cracks which were caused by the obvious banded segregation and more inclusions in microstructure of the adjusting nuts. At the same time, the tempering temperature is too high, and reticular ferrite appeared on both sides of the cracks because of decarburization.