Microstructures, Simulations and Solidification Behaviors of A356 Semisolid Aluminium Alloy Prepared by Stirring Integrated Transfer-Heat Technology under Different Cooling Mediums

Abstract

Based on the theory of grain refinement, the microstructures and simulations of A356 semi-solid aluminum alloy under different cooling mediums were studied. The experiment and simulation results show that water cooling is better than any other cooling mediums. Combined with the simulation of stirring and heat dissipation in SIT device, the changes of temperature field and solid fraction of the melt were studied to help understand the nucleation, growth and solidification behavior under the SIT process. During the process, the temperature field of the melt becomes relatively uniform from a larger temperature gradient and the continuous cooling speed is increased. The results also indicate that compared with traditional casting, the microstructure cooled by water are composed of refined rosiness and nearly spherical particles. With the increase of cooling degree, the average grain size decreased from 206μm to 186μm. The solid fraction increases from 4.4% to 12.2% under the no-cooling and air-cooling conditions, while it is more uniform, increasing from 5.1% to 8.8% due to the water cooling.