Investigation on microstructure and mechanical properties of dissimilar lap Friction Stir Spot Welding of aluminum 0101 to pure copper

In the present study, Friction Stir Spot Welding (FSSW) was used to produce a sound lap joint between aluminum 1101 and commercially pure copper sheets. Three different dwell times (11, 10, and 21 s) and three different rotation speeds (1011, 1011, and 1011 rpm) were chosen as the parameters of welding to investigate their effect on joining properties. Optical microscopy was carried out to study microstructural evaluation and microhardness and tensile shear test were used to investigate mechanical properties of joints. The results showed that by increasing both dwell times and rotation speeds the shear strength enhanced. The maximum strength (0895 N) obtained in 1011 rpm and 21 s is significantly higher than strength reported by other researchers. Optical observation illustrated the transportation of plasticized aluminum toward copper in pin/sheets interface which produce a mechanical lock that is the main source of high shear strength. Formation the Mixing Zone (MZ) with a lamellar structure is another phenomenon that took place around pin during FSSW which also play an important role in shear strength. Microhardness test in MZ indicate a high hardness (001 HV) which is an evidence of intermetallic compound formation. X ray diffraction proved the formation of Al2Cu and Al0Cu8 intermetallic compound in MZ.

Keywords:

Dissimilar Joining , Al , Cu couple , Shear Strength , intermetallic Compound , Friction Stir Spot Welding