The Effect of Tool Rotation Speed on Hardness, Tensile Strength, and Microstructure of Dissimilar Friction Stir Welding of Dissimilar AA5083 and AA6061-T6 Alloys

Abstract

The welding between two different grades of aluminum alloy, specifically AA5083 and AA6061-T6, is very difficult to obtain optimal results when using conventional welding methods such as TIG/MIG welding. Therefore, a solid-state joining technique is highly recommended to overcome these problems, one of which is friction stir welding (FSW). The effect of rotation speed on microstructure, microhardness, and tensile properties of dissimilar Friction Stir welded AA5083 and AA6061-T6 aluminum alloys were investigated. Three different rotation speeds (910, 1500, and 2280 rpm) were used to weld the dissimilar alloys. The metallographic analysis of joints showed the presence of various zones such as BM (base material), HAZ (heat affected zone), TMAZ (thermo-mechanically affected zone), and NZ (nugget zone) were observed and analyzed by mean of optical and scanning electron microscope. The results showed that increasing the rotation speed from 900 to 2280 rpm made grain coarsening in NZ and the mass distribution of the material is more evenly distributed, as well as increased hardness and tensile strength of the joint. The highest values in microhardness in NZ and tensile strength at the join were founded at the speed of 2280 rpm and 1500 rpm which was similar to 2280 rpm, respectively.