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The present study aims at finding the residual stresses on aluminum hybrid composites during turning operation. The composites with varying percentage by weight reinforcement of 2, 4, 6 and 8 RHA and SiC in equal proportions were fabricated using two stage stir casting process. X-ray diffraction was used to study the residual stresses on the surface layer of the machined surface. It was observed that the residual stresses generated during casting were considerably larger when compared to the stresses generated during machining of composites. It was also noticed that the residual stresses were found to decrease with the increase in the reinforcement and increases with the increase in cutting speed. The related mechanisms are explained and presented in this work.

A double stir casting process was used to fabricate aluminum composites reinforced with various volume fractions of 2, 4, 6, and 8 wt% RHA and SiC particulates in equal proportions. Properties such as hardness, density, porosity and mechanical behavior of the unreinforced and Al/x%RHA/x%SiC (x = 2, 4, 6, and 8 wt%) reinforced hybrid composites were examined. Scanning electron microscope (model JSM-6610LV) was used to study the microstructural characterization of the composites. It was observed that the hardness and porosity of the hybrid composite increased with increasing reinforcement volume fraction and density decreased with increasing particle content. It was also observed that the UTS and yield strength increase with an increase in the percent weight fraction of the reinforcement particles, whereas elongation decreases with the increase in reinforcement. The increase in strength of the hybrid composites is probably due to the increase in dislocation density. A systematic study of the base alloy and composites was done using the Brinell hardness measurement and the corresponding age hardening curves were obtained. It was observed that in comparison to that of the base aluminum alloy, the precipitation kinetics of the composites were accelerated by adding the reinforcement. This effectively reduced the time for obtaining the maximum hardness by the aging heat treatment.