Influence of Process Parameters on Microstructure and Mechanical Properties ofAS21-SiC Composites through Two-Step Stir-Casting

This work aims to focus on fine precipitation of Mg-Si compound in AS21 alloy system by the dispersion of SiC reinforcement through stir-casting in two steps. Dual step stir-casting at a melt temperature of 680 (o) C, 700 (o) C, and 720 (o) C with varied stirring rates (S) manufactured the AS21 alloy composite having 2, 4 and 6 wt.% of SiC. The Taguchi L-9 experiments were implemented with three processing factors (wt.% of reinforcement, melt temperature and stirring speed) at three levels in order to acquire optimum conditions. Metallographic examinations depict the formation fine grain structure and precipitation of fine Mg-Si compound with the SiC reinforcement. The ANOVA analysis identified the SiC reinforcement as the most effective parameter influencing the mechanical properties of AS21 alloy composites. The tensile strength of 199.35 MPa was attained at the optimum two-step stir casting conditions: i.e. melt temperature of 720 (o) C, stirring speed of 600 rpm by adding 6 wt.% of SiC in AS21 alloy. The influence of SiC variation on Mg2Si compound by duel step stir casting were discussed in detail.