An Experimental Investigation on micro-Friction Stir Welding (μFSW) Process Using Pinless Tool

Efficient lap welding of very thin sheet metals (thickness ≤ 1 mm) is critical in industries like automobile, aerospace and so on. Micro-friction stir welding (µFSW) has shown its ability to join such thin sheets. In the present research, a pinless tool has been used to weld 0.8 mm thick aluminum alloy (AA6061-T6) sheets in lap configuration by varying the tool rotational speed (TRS) from 2000 to 3000 rpm and welding speed (WS) from 100 to 200 mm/min, with a constant plunging depth of 0.2 mm. Lap shear tests and microhardness tests have been conducted to evaluate the joint’s mechanical strength. It is found that the process parameters have significant influence on the mechanical properties of the welded joints. Increasing TRS from 2000 to 3000 rpm shows better joint formation, indicating adequate heat generation and better material intermixing. The optimal combination of parameters appears to be 3000 rpm (TRS) and 100 mm/min (WS) displaying a joint strength of 230.13 MPa and microhardness of 92.3 HV. Defects like flash, surface galling, irregular shoulder marks have been found in very small quantities in the weld region.