挤压7A04铝合金轮辋断裂失效分析

Fracture failure analysis of extruded 7A04 aluminum alloy wheel rim

利用Instron万能试验机研究了失效7A04铝合金轮辋轮辐径向、轮辐切向及轮毂轴向的拉伸性能,采用金相显微镜和扫描电子显微镜分析了轮辐、轮毂及卡槽失效部位的显微组织和断口形貌。结果表明,7A04铝合金轮辋轮辐径向、轮辐切向及轮毂轴向的显微组织及力学性能均符合要求;7A04铝合金轮辋失效的主要原因是在加工的过程中卡槽位置圆角过小,在服役过程中卡槽处产生应力集中,进而引发了多源性疲劳断裂以及韧脆混合型断裂,最终导致轮辋失效。

The tensile strength at spoke radius direction, spoke tangent direction and wheel rim axis direction have been investigated using Instron universal experiment machine for fail- ure 7A04 aluminum alloy wheel rim. The microstructure of spoke, hub, failure fracture mor- phology and microstructure of clamp groove have been investigated using optical microscopy （OM） and scanning electronic microscope （SEM）. The results show that the mechanical properties and microstructure of the spoke and wheel rim can meet the requirement of the us- er. The main reason of fracture failure is due to the small chamfer in clamp groove, which re- sults in stress concentration during service. That leads to fatigue fracture, mixed mode brittle and ductile fracture, and finally lead wheel rim failure at all.