Influence of Tool Probe Offset and Traverse Speed on Microstructure and Mechanical Properties of Friction Stir Weld Dissimilar Joints of AA2024-T351 and AA7075-T651

Abstract

The effect of tool probe offset and varying traverse speed on the mechanical and metallographic characteristics of friction stir weld dissimilar joints of AA2024-T351 to AA7075-T651 in butt joint configuration produced using taper-threaded tool with constant tool rotation speed, 650 rpm and plunge depth, 6.2 mm are investigated. The tool traverse speed was varied from 20 to 120 mm/min along the weld length with the different tool probe offset condition. Optical microscopy and scanning electron microscopy are used to characterize the grain size and microstructural modification at the weld nugget zone (WNZ). The effect of different tool offset conditions in conjunction with varying traverse speed results in banded structure of alloys, partial material mixing and unmixed region at the WNZ. The combination of tool offset distance of 1 mm towards AA7075-T651 with traverse speed, 110 mm/min yields maximum ultimate tensile strength, 436 MPa, yield strength, 375 MPa, elongation, 14% and weld joint efficiency, 92%. © 2020, Springer Nature Singapore Pte Ltd.