Influence of SiC Particles on Mechanical and Microstructural Properties of Modified Interlock Friction Stir Weld Lap Joint for Automotive Grade Aluminium Alloy

Abstract

The present requirement of the aerospace industry is seeking light-weight joining material that satisfies the technical and technological requirements with better mechanical characteristics. Aluminum alloy with spot-welding process meet the requirements of modern demands. In this present paper, a modified-interlock friction stir weld lap joint is induced to join AA8011-AA7475 with different wt% of SiC particles. Friction stir machine process parameters were tool rotational speed 1600 rpm, plunge speed rate 0.08 mm/s and traverse speed 40 mm/s maintained constantly. Mechanical and metallurgical characterizations were investigated. EDS analysis and microstructure confirmed the presence of silica particles in the NZ of the weld joints and uniformed homogenous distribution of the particulates throughout the weld. Joints made with SiC particulates showed improved static properties because intensive softening occurred in the stir zone leading to Si-Al-based precipitate particulates. The fracture test showed that the joints with SiC had a ductile fracture. AA8011-AA7475 with 2 wt% SiC showed maximum hardness, tensile strength of 229 HV, 192 MPa and a decrease in elongation was observed from 9.5 to 5%. AA8011-AA7475/2 wt% showed improved hardness, tensile strength and elongation suitable for aircraft wing stringers application.