抛光的铸造铝合金车轮表面凹坑的预防

Prevention of Pits on Surface of Polished Aluminum Casting Alloy Wheels

经抛光的压铸A356．2铝合金车轮表面发现有凹坑缺陷。为此，对有缺陷的车轮进行了化学成分分析和显微组织检测，以揭示形成凹坑的原因。结果发现，车轮表面凹坑是一种铸造微观针孔，针孔缺陷的产生与铸件的造型、铸造工艺、熔炼工艺、铸模结构及冷却工艺等因素密切相关。通过铸模采用水冷替代风冷，有效减少了抛光后A356．2铝合金车轮表面的凹坑缺陷。

Low-pressure cast and polished A356.2 aluminum casting alloy wheels exhibited defective pits on their surface. For this fact, the wheel having the pit was subjected to chemical composition analysis and to microstructural survey in order to discover the reason why the pits produced. The results indicate that the pit belongs in pinhole which forms during pouring, and closely related to casting molding, pouring process, melting process, mould design and cooling procedure. The pits on the surface of A356.2 aluminum alloy wheel after being polished were considerably lessened by cooling the mould in water rather than in air.