Abstract:Friction stir welding (FSW) has been extensively adopted to fabricate aluminium alloy joints by incorporating various welding parameters that include welding speed, rotational speed, diameters of shoulder and pin and tool tilt angle. FSW parameters significantly affect the weld strength. Tool tilt angle is one of the significant process parameters among the weld parameters. The present study focused on the effect of tool tilt angle on strength of friction stir lap welding of AA2014-T6 aluminium alloy. The tool tilt angle was varied between 0° and 4° with an equal increment of 1°. Other process parameters were kept constant. Macrostructure and microstructure analysis, microhardness measurement, scanning electron micrograph, transmission electron micrograph and energy dispersive spectroscopy analysis were performed to evaluate the lap shear strength of friction stir lap welded joint. Results proved that, defect-free weld joint was obtained while using a tool tilt angle of 1° to 3°. However, sound joints were welded using a tool tilt angle of 2°, which had the maximum lap shear strength of 14.42 kN and microhardness of HV 132. The joints welded using tool tilt angles of 1° and 3° yielded inferior lap shear strength due to unbalanced material flow in the weld region during FSW.

Key words: AA2014 aluminium alloy; friction stir lap welding; tool tilt angle; lap shear strength; microstructure