EFFECT OF PREHEAT AND POST HEAT TREATMENT ON THE PROPERTIES AND THE MICROSTRUCTURE OF ALUMINIUM-6082 BY FRICTION STIR WELDING

Abstract

Friction stir welding of 6082 AA-T6 was performed using three different combinations of feed rates (40, 70 and 90 mm/min) and tool rotational speeds (664, 708 and 931 rpm). Mechanical properties of the weldments were evaluated by hardness measurements on the transverse section and tensile testing, while microstructure evaluation was done by optical microscopy. A fundamentally misfortune in hardness in the mix zone(SZ) was noted than in the thermo-precisely influenced zone(TMAZ) because of disintegration of β' and β" second stage particles. A post weld heat treatment (PWHT) of 180 °C for 5h was given to the weldments for all welding parameters and the mechanical properties and microstructure were re-examined. The hardness and quality were marginally recuperated and this was credited to the conceivable reprecipitation of the β" encourages. A preheat state of 200 °C for 1h was performed to examine the mechanical properties and microstructure.