Hybrid self-reacting friction stir welding of AA 6061-t6 aluminium alloy with cooling assisted approach

Abstract

In the present work, self-reacting friction stir welding of 6 mm thick Al 6061-T6 was processed considering two novel approaches as different temperatures of the water (1◦C and 30◦C), and methods of use (spraying and enveloping top surface) using water as cooling media. The four experiments as natural air cooling (NAC), spraying with room temperature water mist (S-RM), spraying with ice water mist (S-IM), and cooling with room temperature water jet (C-RJ) were performed. The thermal profile, microstructure, microhardness, and tensile properties were investigated for all the joints. The lowest hardness location was heat affected zone in NAC and it was the boundary of the thermo-mechanically affected zone and weld nugget zone in all cooling assisted joints. The C-RJ cooling assisted joint resulted in the highest tensile strength of 189.16 MPa which is 8.17% higher than the conventional self-reacting friction stir welded joint.