镁合金薄壁压铸件表面亮斑形成原因

Analysis of the Formation of Light Spots on the Surface of Die-cast Magnesium Alloy Components

摘要: 镁合金压铸件在经过化学转化处理后,表面经常会有亮斑出现.分析认为造成亮斑的主要原因是压铸件在压铸过程中由于模具表面存在热点使镁液冷却速度变慢,而在压铸件表面形成了异常长大的先析出α相.由于先析出α相和共晶组织(α+β)的耐蚀性不同,因此在形成化学转化膜过程中,形成了成分不同的化学转化膜,使表面呈现出亮斑.

Abstract: After chemical conversion treatment of magnesium die-cast components,light spots often appear on their surfaces.The reason for such a problem was analyzed.It shows hot spots formed on the die surface during casting process decrease the solidification velocity of molten magnesium and big primary α phase is formed on the surface of casting.The different corrosion resistance of primary α phase and eutectic microstructure(α+β) makes the composion of chemical conversion coating different, so that the surface with primary α phase is discolored and light spots appear.