Effect of initial temper on mechanical properties of friction stir welded Al-2024 alloy

The microstructural evolution and resultant mechanical properties during the friction stir welding (FSW) of precipitation strengthened aluminium alloys depend on initial temper as well as FSW process parameters. Al-2024 alloy under two different initial tempers, T3 and T8, was used in the present study. FSW bead-on-plate runs were performed at different values of process parameters (tool rotation rate and tool traverse speed). Microstructure and mechanical properties of the nugget region and heat affected zone (HAZ) were evaluated. Differential scanning calorimetry (DSC) revealed that in the nugget region, presence of Guinier–Preston–Bagaryatskii (GPB) zone results from the partial dissolution of Al₂CuMg phase. The microstructure and tensile properties were found to be independent of the initial temper of the material in the nugget region. In the HAZ region, tensile properties increased at higher heat index values for T3 condition, and decreased monotonically for T8 condition.