Indian Journal of Science and Technology

Abstract

An experimental investigation has been carried out on microstructure, micro hardness distribution, tensile properties and fracture surface morphology of weld butt joints of 6061 T6 aluminum alloy. Two different welding processes have been considered: a conventional tungsten inert gas (TIG) process and an innovative solid state welding process known as friction stir welding (FSW) process. Micro hardness distribution results showed a general decay of mechanical properties of TIG joints, mainly due to high temperature experienced by the material. Instead, in FSW joint, lower temperatures are involved in the process due to severe plastic deformation induced by the tool motion and lower decay of mechanical properties. In the nugget zone a slight recovery of hardness is observed due to recrystallisation of very fine grain structure. Hence from industrial perspectives, FSW process is very competitive as it saves energy, has higher tensile strength and prevents the joints from fusion related defects.
Keywords: Friction stir welding, tungsten inert gas welding, micro hardness, tensile properties, fractography.