Effect of Pin Profile on Friction Stir Welded Aluminum Matrix Composites

To clarify the role of pin profile geometry on some properties of friction stir welded of the considered aluminum matrix composites (Al-4 wt% Mg, reinforced with 1wt% SiC and 1wt% graphite particles) plates of 8 mm thickness were fabricated by compocasting method then annealed at 400 degrees C for 2 h. Tools with different pin profiles (square, hexagonal, and octagonal) were manufactured to be used for friction stir welding (FSW) of aluminum matrix composites plates at four different levels of welding (transverse) and rotational speeds. The effects of these pin profiles on microstructure and some mechanical properties of the friction stir welded joints were studied. The results show that the plates welded by square head pin have better properties compared to the other pin profiles. This pin seems to cause better grain refinement and redistribution of SiC and graphite particles in the welded nugget zone (NZ) than the other two types. This has led to better improvements in the considered mechanical properties. Also, these properties were improved by increasing welding speed, while increasing the rotational speed has a diverse effect on them.