Effect of Si Content on Strip Thickness and Solidified Structure in High-Speed Twin-Roll Cast Al-Si Alloy Strips

摘要

Al-Si alloy strips with various Si compositions were cast by using high-speed twin-roll caster. The strip thickness measurement and microstracture observation were carried out. The strip thickness changed prominently with varying Si composition. The strip thickness change was considered to result from change in solidification manner (skin or mushy-type solidification) depending on freezing temperature range of the alloy. The solidified structure of the mid-thickness region is also greatly influenced by the freezing temperature range. Internal crack appeared at the mid-thickness region of 2 mass% Si strip, in which the central band consists mostly of globular grains and equiaxed dendrites. The internal cracking is considered to be related with residual liquid in the central band region and its solidification.