低压铸造铝合金轮毂内部缺陷分析及改进措施研究

Defects Analysis and Prevention Measures of Low Pressure Die Casting of A356 Aluminum Alloy Wheels

对低压铸造A356铝合金轮毂内部缺陷进行了分析,对轮毂各个部位的微观组织和力学性能以及试样拉伸断口形貌进行了检测。结果表明:轮辐和轮心部位α-Al的二次枝晶臂间距(SDAS)分别为48μm和55μm,易出现少量的缩孔、缩松以及气孔等铸造缺陷,局部区域存在变质不良的Si相及针状、鱼骨状的铁基化合物;外胎圈座附近易出现偏析现象,造成局部性能不佳;轮缘部位晶粒细小,Si相变质良好。为提高产品质量,总结了压铸铝轮毂组织中易出现的各种缺陷并提出相应的改进措施。

The defects of low pressure die casting A356 aluminum alloy wheels were investigated.The microstructure,mechanical properties and tensile fracture morphologies at different position of the wheels were observed and analyzed.The results show that the average secondary dendrite arm spacings（SDAS）of the wheel rib and wheel center were 48 μm and 55 μm,respectively.The casting defects including shrinkage cavity,shrinkage porosity and pore were discovered in wheel rib and wheel center.Moreover,the eutectic silicon with bad modification,needle-like and fishbone iron bearing compound,segregation of eutectic silicon were found in some regions,which could affect the over-all properties of wheels,but in the wheel rim the grains were fine and the eutectic silicons were well modified.To improve the quality of castings,the defects that easy occur in low pressure die cast aluminum alloy wheels were summarized and some improvement measures were brought forward.