Optimised experimental evaluation of Surface roughness of age hardened & ground Al6061/SiC/Graphite composite alloys using Taguchi Orthogonal Array

Aluminium alloy (Al6061) is made into composite with Silicon Carbide (SiC) at 10 wt% and graphite (2wt%, 8 wt% & 10 wt%) by stir casting. The fabricated composites were further subjected to hardening at dissimilar temperatures (level 1-150 °C, level 2-175°C & level 3-200°C) and aging (4,8,10) hours. For understanding the consequence of graphite, heat treating temperature and aging on the surface roughness of the surface grinded samples, the total number of experiments were optimised using Taguchi’s Orthogonal array. It was found that Al6061/SiC/Graphite composite with 10 wt% graphite, heat treated for 10 hours at 150°C had 0.50 μm as the lowest surface roughness and highest hardness of 79 VHN. The relationship between heat treating temperature (150 ° C), hardness & graphite content to that of surface roughness was found to be indirect whereas for all other samples this relationship ceased to exist.