A Novel Semisolid Rheo-Rolling Process of AZ31 Alloy with Vibrating Sloping Plate

Abstract

A novel semisolid rheo-rolling process of AZ31 alloy was achieved by combining the shape rolling mill with the vibrating sloping plate device. The process is expected to be developed as a high-speed, semisolid roll-casting technique. During the process, due to the strong cooling rate by the sloping plate and stirrings caused by vibration and metal flow, three mechanismsheterogenous nucleation, eruptive nucleation, and nucleus multiplicationexist, which lead to fine spherical or rosette grains formation. Two grain-growing styles, direct globular growth, dendrite growth, and fracture happen on the sloping plate surface, which also devotes to the fine non dendrite formation. During the rolling process, the solid grain of the slurry is elongated a little, and its original shape is basically maintained. If the casting temperature is too high, the liquid segregation occurs. At the casting temperature range of 650690 degrees C, AZ31 alloy strip with a cross section size of 4x160mm was prepared by the proposed process. The product has good quality surface and homogenous microstructure. The mechanical properties of the product are higher than that produced by conventional roll casting.