Influence of shoulder diameter on hybrid surface composite of AA7075-T651/SiC/Graphene via friction sir processing

Abstract

Friction stir processing is a unique method for improving a base metal's microstructure and mechanical properties by adding reinforcement particles. In this study, three different shoulder sizes are used to fabricate the hybrid surface composites AA7075-T651/SiC/Graphene, and the effect of shoulder diameters on composite properties is critically investigated. The optical microscopy technique is used to examine the macro and microstructures of friction stir processed samples. Microhardness and wear tests are used to measure the mechanical and tribological properties of the produced composites. According to recent study work, 21 mm shoulder diameter revealed equiaxed grain microstructure, which is responsible for the increased microhardness and wear. The smaller grain size of 3.2 µm is attained by dynamic recrystallization. The superior microhardness of 194 HV is due to the hall patch relation and the Orowan strengthening mechanism. The decreased COF and wear rate were due to the sample's higher hardness and lubricative behavior of graphene particles.