Experimental and Numerical Investigation on Friction Stir Welding of Dissimilar Materials

Abstract

Currently AA2xxx-Cu alloys showed larger applications in the defence sectors and in aerospace industries due to high strength to low weight ratio and toughness. Friction stir welding is a solid state joining process where a rotational non-consumable tool is used to join similar as well as dissimilar materials. By the stirring action of tool heat is generated which causes plastic deformation of materials and hence the weld is prepared. The aim of the present study was to develop a thermal numerical model of FSW and the effects of process parameters on the mechanical properties as well as microstructures for dissimilar material AA2014-T6 and pure Copper. FSW in a butt joint configuration was carried out between AA2014-T6 and pure Copper placing AA2014 on AS and Cu on RS. Temperature profiles were observed by inserting K-type thermocouples in the mid-thickness at various locations of the plate. ALE formulation was used in preparing 2D dynamic mesh model. A thermal numerical model was prepared in ANSYS to compare the simulated temperature profiles with the experimental temperature profiles and both the temperature profiles were found to be in good agreement. Microstrucutures and mechanical properties of the welded portion were studied. Maximum joint efficiency was found to be 50% of the base material while offsetting the tool towards Al side. Maximum hardness value of 204Hv was found in nugget zone when friction welding of FSW welded joint was carried out at tool rotational speed of 1400rpm, welding speed of 125mm/min and 0mm tool offset condition. Some dimples and secondary phase particles were found in the SEM test which may be responsible for higher joint strength and hardness values.