Investigating the Microstructure and Mechanical Properties of Friction Stir Weld Joints of Solution Hardening Aluminium Alloy AA5086

Friction stir welding is one of the most suitable welding processes to join aluminum alloys, thanks to many economical and technical advantages associated with its use. This paper investigates effect of friction stir welding on the microstructure and mechanical properties of solid solution hardening Al-Mg-Mn aluminum alloy. Friction stir weld joints were developed using optimum combination of rotary speed and welding speed. The microstructure evolution in friction stir weld joints was studied by optical microscopy. Fine recrystallized grains were observed in weld nugget zone while thermo-mechanically affected zone showed distorted and unrerystallized grains. Microhardness profiles and stress-strain curves were developed for friction stir weld joints and base material. Friction stir weld joints showed mechanical properties approximately equal to base material. Further, fracture surfaces were investigated using scanning electron microscope to study the mode of fracture.