Fabrication of Mg alloy strips by strip casting

Abstract

A feasibility study has been made to fabricate the Mg alloy strips by strip casting. AZ31 and AZ91 alloys were strip cast into 2 mm thick strips. The microstructure of the as-cast AZ31 alloy strip consists of columnar zones near the roll side and equiaxed zones in the mid-thickness region. On the other hand, AZ91 alloy strip shows the fine, equiaxed dendrites through the thickness of strip. There is a variation of secondary dendrite arm spacing through the thickness of strips, showing the smallest value at the roll side and the largest value at the center of strips. Yield and tensile strengths of strip cast AZ31 alloy in H24 condition is quite comparable to those of commercial ingot cast AZ31-H24 alloy; however, the former has somewhat lower ductility than the latter. The AZ91 alloy strip, on the other hand, has much higher values of yield and tensile strengths with equivalent ductility compared to the commercial ingot cast AZ91 alloy in T4 and T6 conditions. This is due to the refinement of microstructure by strip casting. It shows that the strip casting can be a viable process for the fabrication of Mg alloy strips.