Microstructure and mechanical properties of friction stir spot welded dissimilar aluminum alloys

Abstract

The present study was the result of an investigation of friction stir spot (FSS)-welded similar aluminum alloys 2024-T3 joint and 7075-T6 joint and dissimilar aluminum alloy 2024-T3-7075-T6 joint. The mechanical, microstructural, and tribological behavior of the different FSS-welded specimens were characterized for effects of influence of the input process parameters. The dissimilar FSS-welded 2024-T3-7075-T6 joint exhibited uniform distribution in material flow in the welded zone. A marked improvement in microhardness was noted when it increased from 30 to 40.94 HV, while an increase in tensile strength from 128 to 166.3 MPa was observed for the FSS-welded dissimilar 2024-T3-7075-T6 joint alloy. The dissimilar alloy weld joint exhibited improved microhardness and tensile properties than their counterparts in both variants of the similar FSS-welded specimens, with a 35.6% increase in microhardness for the bottom plate in welded nugget zone and improvement of 13.14% and 5.54% in ultimate tensile strength when compared to aluminum alloy 2024-T3 joint and 7075-T6 joint under same welding parameters.