STUDY OF MECHANICAL PROPERTIES OF FRICTION STIR WELDED DISSIMILAR ALUMINIUM ALLOYS

Abstract

The relatively new joining process of friction stir welding (FSW) is a solid state joining process which does not involve the melting of the base materials. Aluminium alloys AA5083-H32 and AA6061-T6 have been previously joined with other types of aluminium alloys, very little work has been reported on the joining of these two materials by FSW. In this research, dissimilar joints were made using three different tool rotation speeds of 630 rpm, 1000 rpm and 1600 rpm and three traverse speeds which were 16, 20 and 40 mm/min. Three tool configuration were used and these had different pin to shoulder diameter ratios of 2.5, 3.0 and 3.5. Full factorial face centred central composite design was used to minimise the number of experiments done. Response surface methodology was used to optimise the parameters as well as perform regression analysis to determine the interrelationships between the three parameters used in the joining process. Three different regions namely base material, heat affected zone, thermo-mechanically affected zone and nugget zone have been observed in the weld. The joining process was successful with a tensile strength above 70% of the base material and a fine grained microstructure which was a result of recrystallization.