Influence of tool pin profile and welding parameters on microstructure and mechanical properties of dissimilar friction stir welded AA2024 to AA7075 alloys.

Purpose: The paper aims to produce aluminium welds in the solid state with good specifications and the least amount of welding defects by using the friction stir welding method (FSW) and different tool pin profiles and welding parameters. The research investigated the mechanical characteristics and microstructure of a friction stir welded dissimilar aluminium alloy (2024-T3 to 7075-0) through thickness produced by varying welding settings and three different FSW tool pin shapes. Design/methodology/approach: The objective is to obtain the welds with the least amount of welding defects in the solid state by using the friction stir welding method (FSW), designing the tool pin profiles, and changing the rotation speeds. Findings: According to tensile strength and micro-hardness tests, tool rotation of 2000 rpm and square pin profile were the best compared to other working parameters. The greatest hardness and highest tensile strength of FSWed dissimilar aluminium joints have been 144 HV and 215 MPa, respectively, when using the square pin profile at a tool rotation speed of 2000 rpm. The hardness and tensile strength of FSWed dissimilar aluminium alloy joints increase with the tool rotation speed. Microstructural observations of the FSWed dissimilar aluminium joints using a square pin profile at the tool rotation speed of 2000 rpm exhibited the weld zone's high weld quality. Additionally, there were no defects in the weld zone. The fracture surface of the FSWed joint indicated a ductile fracture type. Research limitations/implications: With many regions on either side of the weld with varied compositions, microstructures, and characteristics, the resulting welds of dissimilar alloys might result in unsatisfactory weld joints. Practical implications: The weld zone's exceptional weld quality was demonstrated by microstructural investigations of the FSWed dissimilar aluminium connections utilising a square pin profile at a tool rotation speed of 2000 rpm and feed rate of 20 mm per minute. Application in aerospace, shipbuilding and marine, railway, construction, electrical industries, and land transportation. Originality/value: The original value of the paper is the production of welds from dissimilar aluminium alloy (2024-T3 to 7075-0) with the least amount of welding defects by changing the tool pin profiles and tool rotation speeds using the friction stir welding method. [ABSTRACT FROM AUTHOR]