FRICTION STIR WELDING OF Al ALLOYS

Abstract

In the present study the effect of the tool rotational speed on the mechanical properties and resultant microstructure of friction stir welded 2014 aluminium alloy was investigated. In this investigation an attempt has been made to correlate the influences of rotational speed on nugget zone formation. Triangular tool pin profile has been used to fabricate the joints at two different rotational speeds of 1000 rpm and 1400 rpm with constant welding speed of 63 mm/mm. The formation of nugget zone has been analysed using optical microscopy. Hardness of the nugget zone, TMAZ and HAZ was measured with Vickers hardness tester. Fracture surfaces were examined by SEM to understand the mechanism of failure. After welding, post-weld heat treatment was carried out to study the effect of abnormal grain growth. The variation in mechanical properties at different rotational speeds ascribed to the precipitate dissolution in the alloy. Moreover, one more study on the effect of the tool geometry and welding parameters on the mechanical properties of marine grade 5083 aluminium alloy was carried out. Two different tool pin profiles (straight cylindrical and triangular) have been used to fabricate the joints at different tool rotational and welding speeds. For each pin profile two rotational speeds of 1400 rpm and 700 rpm with two welding speeds of 100 mm/min and 40 mm/min were utilized. The formation of nugget zone has been analysed using optical microscopy. For both alloys tensile properties of the joints have been evaluated in perpendicular direction of the weld