Study on Microstructure and Strength of Friction Stir Spot Welding On Copper Alloy Sheet

Friction Stir Spot Welding is the derivative of Friction Stir Welding (FSSW). It is a solidstate
joining process of metal sheets with the thickness not more than 3 rnrn. Most of the
process is being used in the automotive industry. FSSW is a process without lateral
movement of the tool compared to Friction Stir Welding. Two sheets of different
combinations of material were welded by using the FSSW process. The thickness of the
sheet 0.9 rnrn. The combinations of material are Aluminum alloy to Aluminum alloy,
Copper Alloy to Copper Alloy and Copper Alloy to Aluminum alloy. For each of the
combination, the tool rotational speed were varied with 2000, 3000, 4000 rpm each.
Then, 3 samples of welded sheets with tool rotational speed of 3000 rpm were observed
on the microstructure using the optical microscope. Three different welded areas of
affected by the FSSW were seen under the microscope to be characterized. The other
samples were taken to be tested on the tensile strength using the Universal Tensile
Strength Machine. The load resulted from the test were calculated to get the value of
tensile strength for the welding process.