Performance Analysis of Varying Tool Pin Profile on Friction Stir Welded 2050-T84Al-Cu-Li Alloy Plates

In this paper, different tool pin profiles, namely taper-threaded, triangular, and hybrid are used to join 5-mm-thick 2050-T84 Al-Cu-Li alloy by friction-stir-welding. The experiments were conducted using a one-variable-at-a-time approach by varying the geometry of tool pin profile and kept constant values of tool rotational speed, tool traverse speed, and tool tilt angle as 1400 rpm, 180 mm/min, and 2°, respectively. The objectives of this paper are to determine the effects of varying tool pin profile on force–torque behavior, microstructure, grain size distribution, tensile properties, and mode of tensile failure. It was observed that the hybrid tool produced less flash, less vertical downward force(14340.49N), low average grain size (11.27 µm) in the nugget zone, and larger weld bead area along with higher tensile strength (418.98 MPa), joint efficiency (78.44%), and micro-hardness (147HV0.1) when compared to other tools. The fractography analyses were performed using field-emission scanning electron microscope and observed ductile mode of failure for all friction stir-welded joints.