Investigations On Thermal Equilibrium Conditions Of A356 Aluminum Alloy In Rheocasting

In this paper, semi-solid slurry was prepared by direct thermal method and thermal equilibrium method, independently developed the experimental equipment of heat balance method. Made a study on the influence of process parameters in semi-solid slurry preparation to microstructure of A356 alloy semi-solid slurry, and simulated the preparing process of direct thermal method slurry by AnyCasting software.Direct thermal method experiments showed that semi-solid slurry prepared by this method possessed a more favorable microstructure than slurry prepared by conventional casting.The best slurry was obtained if the outer diameter of circular traight barrel was 38 mm, the wall thickness was 1 mm, the pouring temperature was 635 oC and holding time was 60 s.The average equivalent diameter and average shape factor of the primary solid phase was 47.1 ?m and 0.83 respectively. Under this experimental condition, the slurry weight gradually reduced as the barrel diameter increased and increased first then decreased with pouring temperature increased, it was stable when the holding time was in range of 60-120 s.In order to meet production needs, the optimum pouring temperature was 630 oC when cone frustum barrel with average diameter of 70 mm was applied. The simulation results showed that by direct pouring, a large amount of oxide or air was involved and the chilling effect of core slurry was poor, the corresponding microstructure was not satisfactory which average equivalent diameter reached to 77.6 ?m, and the shape factor was 0.71.Thermal Equilibrium method improved the casting way, the supercooling degree of core melt and the consistency of the slurry. The best slurry was obtained if the outer diameter of heat pipe was 34 mm, the wall thickness was 1.1 mm, the length was 210 mm and the pouring temperature was 630 oC. Average equivalent diameter and average shape factor of the primary solid phase was 64.3 ?m and 0.81 respectively. The results showed that the Semi-solid slurry weight gradually reduced as the thickness of absorber cylinder increased and the increasing of heat pipe length. The changed diameter of heat pipe created an influence on slurry weight by affected the temperature field.