吊钩螺母裂纹分析

Crack Analysis on Hook Nut

经调质处理的吊钩螺母在机加工时发现内孔有纵向裂纹。采用化学成分分析、宏观分析和金相分析等方法分析了有裂纹的螺母,又通过改进试验进行了验证。结果表明:由于双液淬火使工件淬火内应力增加,而吊钩螺母的结构形状又使其内孔切向拉应力增大,二者的综合作用导致了吊钩螺母内孔产生淬火裂纹。

The vertical cracks in the bore of the hook nut are found during machining after quenching and tempering treatment. The nuts with cracks are tested by chemical composition analysis, macro-analysis and metallographic analysis etc. , and are validated by the improved test methods. The results show that as the double -liquid hardening to increase quenching stress and the structural shape of hook nut to increases the tangential tensile stress of bore, the combined effect of the two lead to the bore of hook nut produce the quenching crack.