The effect of machining on the surface properties of SiC/Al composites

The machined surface quality of composites is one of the most important factors affecting the actual application of the composites. In this paper the hardness and residual stress of composites in the surface layer affected by machining are investigated. The results indicate that the work-hardening and residual stress of composites in the machined surface layer have some peculiarities. The machined surface hardness of composites reinforced by SiC particles may be lower than that of the unaffected interior material, but the subsurface is hardened evidently, and the average hardening is more remarkable for composites reinforced by fine particles. In the surface of composites reinforced by coarse particles the residual stress may be released due to structural defects, but for composites reinforced by fine particles there is a tendency for compressive residual stress in the surface. Cutting with a larger removal rate increases the possibility for tensile residual stress in the machined surface layer of the composites.