2011 Volume 52 Issue 5 Pages 862-867
The cooling plate method is a simple and effective process for casting ingots in thixoforming feedstock. Analysis of variance (ANOVA) and the Taguchi design method were used in order to reveal the effect on microstructure of major factors in this paper. ANOVA was used to define the effect of parameters such as the pouring temperature, cooling plate angle, holding time after pouring and mold temperature. Among all the factors, pouring temperature exerted the greatest statistically significant effect, especially on grain size. To optimize the conditions to ensure reproducibility, the plate angle and holding time were varied to reduce the effect of the pouring temperature. In the results, a lower plate angle and an extended holding time with a pouring temperature just below the liquid point afforded the formation of a microstructure with rosette-shaped grains in semisolid metal (SSM) slurries. Furthermore, when this slurry was reheated to the liquid/solid temperature, the morphology of the grains was transformed into globular.
