Thin-walled Die-Casting of Al-25%Si Alloy

Abstract

  In this research, the relationship between Si content and fluidity of die-cast Al-Si alloy was investigated. The Si content ranged from 10% to 25%. When a mold with a 0.8mm gap or 1mm gap was used, the fluidity increased with increasing Si content. When the mold gap was 0.5mm, the fluidity of hypo Al-Si was shorter than that of hyper Al-Si alloy. However, in the hypo Al-Si alloy or in the hyper Al-Si alloy in which the Si content was less than 25%, the fluidity was more or less the same. As a result, the fluidity of Al-25%Si was superior to other Al-Si alloys. The influence of adding P, which is usually used for primary Si refinement, on the fluidity and microstructure of Al-25%Si was investigated. Addition of the P did not affect the fluidity and size of the primary Si. Cooling characteristics of Al-15%Si and Al-17.5%Si and the Al-25%Si were investigated using a JIS ship mold. The cooling curve of the Al-25Si gently descended, more slowly than that of Al-15%Si or Al-17.5%Si. It was estimated that the difference of the cooling curve was caused by the difference of latent heat. The huge latent heat of the Al-25%Si made the fluidity excellent. A very thin wall heat sink model, with a fin top of 0.5mm, height of 50mm, and draft angle of 0.5degrees, could be cast by the Al-25%Si. The P did not make the primary Si fine.