Summary: | The present study has investigated the influence of friction stir welding (FSW) on the microstructure and mechanical properties of powder metallurgy processed unmilled AlMg5, AlMg5 milled with 0.3 wt. % stearic acid (SA) and milled AlMg5-0.5 vol% Al2O3 nanocomposites. FSW of unmilled AlMg5 resulted in grain refinement due to dynamic recrystallization induced by the thermo-mechanical processing, thereby increasing the stir zone yield strength (YS) and ultimate tensile strength (UTS) to 160 MPa and 326 MPa when compared to 135 MPa and 300 MPa of base metal, respectively. The friction stir AlMg5-0.5 vol% Al2O3 nanocomposite exhibited superior mechanical properties compared to almost all commercial 5xxx series of Al alloy friction stir welds. However, the friction stir welded AlMg5 milled with 0.3 wt. % SA and AlMg5-0.5 vol% Al2O3 samples showed a slight reduction in UTS values (373 MPa and 401 MPa) compared to 401 MPa and 483 MPa of respective base melal values.
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