MB15模锻件裂纹原因分析

Analysis of the Cause of Cracks of MB15 Die Forging

【目的】某MB15模锻件在进行装配铆接过程中,沿铆接孔纵向及孔附近出现肉眼可见的裂纹,裂纹平直,局部位置有多条裂纹出现,亟须查明原因。【方法】通过宏观观察、微观观察、能谱分析、金相检查及硬度测试、化学成分分析等手段,对该裂纹的开裂性质及开裂原因进行分析。【结果】结果表明:裂纹开裂性质为沿晶脆性开裂,该裂纹产生于锻造阶段,裂纹部位再结晶不完全,与锻造变形温度较低有关。【结论】建议严格控制镁锻件的锻造工艺过程,严格控制变形温度,变形速率等条件,增加零件出厂前检测工序,以降低零件开裂问题,提高供货质量。

[Purposes]During the assembly riveting process of MB15 die forging,it was found that visible cracks appeared along the longitudinal and near the riveting hole.The cracks were straight,and multiple cracks appeared in local positions.Therefore,it is urgent to find out the cause of cracks.[Methods]Through macroscopic observation,microscopic observation,energy spectrum analysis,metallographic ex⁃amination and hardness test,chemical composition analysis,the cracking properties and causes of the crack were discussed.[Findings]The results show that the cracking property of the crack is intergranular brittle cracking,the crack occurs in the forging stage,the incomplete recrystallization at the crack site is related to the lower forging deformation temperature.[Conclusions]It is suggested to strictly control the forging process of magnesium forgings,strictly control the deformation temperature,deformation rate and other conditions,and increase the testing process of parts before leaving the factory,so as to decrease the cracking problem of parts and improve the supply quality.