Microstructure and wear behavior of AA6061/SiC surface composite fabricated via friction stir processing with different pins and passes

In this investigation, the effects of pin geometry and number of passes on macrostructure, microstructure, wear rate and also microhardness profile of 6061-T6 aluminum alloy surface composites fabricated via friction stir processing (FSP) were discussed by reinforcement particles of silicon carbide (SiC). The results show that after each FSP pass, a modify distribution of SiC particles is acquired and the increase in the number of passes reduces the average grain size in stir zone (SZ). Furthermore, it is discovered that pin geometry and pass number play a dominant role in the grain size of SZ and distribution of SiC particles in SZ. It is found that after each FSP pass, wear rate is improved due to the uniform distribution of SiC particles in surface of Al/SiC composite. Additionally, the results show that the square pin and smooth (straight) cylindrical pin have the highest and lowest resistance to wear, respectively.