A downward melt drag single roll caster for casting semisolid slurry

Abstract

A downward melt drag single roll caster (DMDSRC) was devised to make ingots for thixoforming. The DMDSRC was assembled from a copper roll and a nozzle. Therefore, this casting process is very simple. Molten metal was poured into the nozzle, and semisolid slurry was dragged by the rotating roll from the nozzle continuously. Sharing of molten metal or semisolid slurry between the roll and the nozzle was not intended. Cooling of the melt up to semisolid condition by the roll was intended. The roll surface was not coated by lubricant. However, the metal did not stick to the roll, and the semisolid slurry could be exhausted from the slit of the nozzle continuously. Relationship between experimental conditions and microstructure of the aluminum alloy ingot after heating up to the semisolid condition was investigated. Roll speed, gap of the nozzle (gap between the nozzle and the roll), contacting length between the roll and the melt, were important experimental conditions that affected the microstructure. Primary crystal became spherical, and eutectic Si became fine and spherical when the A356 alloy ingot cast by the DMDSRC was heated up to semisolid condition. Average diameter of the spherical primary crystal was about 90 μm.