Improvement of mechanical and microstructural properties of AA 5052-H32 TIG weldment using friction stir processing approach

Abstract

The effect of Friction Stir Process (FSP) on the weld bead of Tungsten Inert Gas (TIG) welded 5052-H32 Aluminium alloy is investigated in this work in terms of mechanical and microstructural characterization. A comparison study was conducted on the FSP treated and unprocessed TIG-welded Aluminium alloy joints. Optical and scanning electron microscopes were used to study the microstructure of the welded joints. Electron backscattered diffraction (EBSD) analysis was performed to analyze the grain size and orientation. The mechanical properties of the weldment were investigated using tensile strength and hardness measurements. The yield strength of unprocessed TIG welded joints was 79.5 MPa, but following friction stir processing, it improved to 129.5 MPa. The tensile strength of TIG-welded joints was 176.5 MPa. However, after post friction stir processing, it was increased to 201 MPa. On friction stir treated TIG welded joints, the elongation values improved from 8.5 percent in TIG welds to 20.75 percent. The refinement of fine grain structure is noticed in the stir zone due to the influence of high stirring action, intense plastic deformation, and frictional heat by Friction stir processing, which improves the mechanical characteristics of the weldment and decreases weld flaws. The tensile fractured surface of the joints was examined using SEM analysis. Brittle failure was seen in the TIG weld joints, and ductile failure with dimples was found in FSPed TIG junctions. The results show that the friction stir processed weldment has better mechanical properties than unprocessed TIG welded joints.