The influences of rotational and welding speeds on microstructures and mechanical properties of friction stir welded Al5083 and commercially pure copper sheets lap joints

In last years, friction stir welding (FSW) method has represented better microstructure and mechanical properties than conventional methods in welding aluminum alloys. Many studies have been performed on joining aluminum alloys in cases of similar and dissimilar FSW lap joints. In this study FSW was used to join sheets of AA5083 aluminum alloy and commercially pure copper and the effects of process parameters including rotational and welding speeds on the microstructures and mechanical properties of the joints were investigated and different joint defects were analyzed. The experiments were performed with rotational speeds of 600, 825, 1115 and 1550 rpm each of them with welding speeds of 15 and 32 mm/min. It was observed that very low or high welding temperatures lead to many joint defects. Also intermetallic compounds and their effects on the mechanical properties of the joints were investigated. The best joint tensile shear properties were achieved at the rotational speed of 825 rpm and welding speed of 32 mm/min.

► Two Sheets of AA5083 and commercially pure copper were used for FSW lap joint.
► Extremely high and low process temperatures lead to joint macro and micro defects.
► Amount of Intermetallic compounds increased by the welding temperature increasing.
► The UTS values mostly decreased by increasing the welding temperature.
► Average joints hardness values mostly decreased by the welding temperature increasing.