Effect of Different Polygonal Pins with Scroll Shoulder on Microstructure, Mechanical and Tribological Properties of Hybrid Surface Composites of AA7075–T651/BN/WC

The scroll shoulder with four different polygonal pins such as square (TS)S, triangular (TS)T, pentagon (TS)P and hexagon (TS)H was creatively designed to make hybrid surface composites of AA7075–T651/WC/BN. The significance of an individual pin with a scroll shoulder on metallurgical, mechanical, and tribological properties was thoroughly explored and analyzed. Material flow, particle dispersion, and zone formation were examined using optical microscopy and field emission scanning electron microscopy with energy dispersive X-ray spectroscopy. Further, the microhardness and wear properties of the made-up samples were examined with each tool design. Based on the findings, a square pin with a scroll shoulder distributes BN and WC particles more uniformly than other combinations because of the unique feature of scroll design and high pulsating action provided by the square pin. The lowest grains were obtained for the square pin with scroll shoulder through dynamic recrystallization. The tool design (TS)S significantly improves the microhardness and wear resistance of the material via reducing clusters, promoting even spreading of particles and producing fine equiaxed grains in the nugget zone.