Optimization of friction STIR welded AA6061 + SiCp metal matrix composite to increase joint tensile strength and reduce defects

Abstract

Friction stir welding has been used in automobiles, locomotive, and aircraft structures. This metal joining process exhibits defects like kissing bonds, micropores, and tunnels. Factors like the joining material, joint thickness, tool geometry, and operating parameters control the defects in friction stir welding. The parameters like tool rotation, tool pass speed, and tool force have a greater influence on the joint quality. In this study, these parameters are considered to augment the strength of the joint and minimize defects. The metal matrix composite consisting of AA6061 matrix and 10 wt. % SiCp reinforcement is joined used FSW. The weld parameters were varied between 731 and 1068 rpm tool rotation speed, 0.33 and 1.17 mm/s tool pass speed, and 11 and 28 MPa tool force. The joint strength varied from 165 MPa to 244 MPa. The numerical analysis using ANOVA revealed that compared between the three parameters, the tool force had greater control over the tensile strength of the joint. After optimization, the joint was made at a tool rotation speed of 910 rpm, tool pass speed of 0.77 mm/s, and tool force of 22.33 MPa. The tensile strength increased to 249 MPa after using the optimized weld parameters. The number of defects in the joint was reduced after using the optimized weld parameters.