Experimental investigation of friction stir welding of dissimilar aluminum alloys

Abstract

Many specific properties of aluminum alloys including light weight newlineand good structural strength enable them to be applied for structural parts. newlineThe demand of aircraft and automotive industries for light weight materials is newlinemet by aluminum alloys. The aluminum alloys AA6XXX and AA5XXX are newlineextensively used in the fabrication of aircraft structures and other structural newlineapplications. AA6351-T6 (Al-Mg-Si) alloys are readily weldable, they suffer newlinefrom severe softening in the Heat Affected Zone (HAZ) because of reversion newline(dissolution) of Mg2Si precipitates during weld thermal cycle. AA5083-H111 newline(Al-Mg-Mn) series aluminum alloy having high levels of Mg which impose newlinepoor weldability by fusion welding process due to its increased susceptibility newlineto stress corrosion cracking behavior. Dissimilar welding of these two alloys newlineis frequently faced in those structures. The conventional fusion welding of aluminum and its alloys is a newlinegreat challenge for designers and technologists due to numerous welding newlinedefects which includes voids, hot cracking, distortion, precipitates dissolution, newlineloss of work hardening, hot cracking and lack of penetration in the joint. Also, newlineconventional fusion welding of aluminum alloys leads to the melting and resolidification newlineof the fusion zone which results in the formation of brittle interdendritic newlinestructure and eutectic phases. The formation of brittle structure in the weld zone leads to the drastic decrease in the mechanical properties like newlinelower hardness, strength and ductility. Friction Stir (FS) welding is a relatively new solid state joining newlinetechnique which offers a number of advantages over the conventional fusion newlinewelding process, and it is used to join aluminum alloys that are difficult to newlineweld by fusion welding processes. It has compatibility to any alloy newlinecomposition, and produces the welded joints by eliminating the defects with newlineimproved mechanical properties. Development of the Friction Stir Welding newline(FSW) has provided an alternative improved way of producing dissimilar newlinealuminum joints,