Comparison of microstructure, texture, and mechanical properties of the SQ and thread pin profile FSW joint of AA6061-T6 with Al2O3 particle reinforcement

Abstract

The paper presents the effect of flat and thread pin profiles on friction stir welding (FSW) of 6061-T6 aluminium alloy with particle reinforcement. The thread geometry on the tool pin enhances the material mixing and improves the material flow in the plastic state. However, in the flat tool pin, the plasticized material was stuck to the side faces of the tool pin surface. The microstructural analysis of the weld specimen revealed that the powder particles were agglomerated in the stir zone (SZ) region in the square tool pin case. However, the powder particles were homogeneously dispersed in the SZ region when the welding was done with the threaded tool pin profile tool. The tensile and hardness tests were also conducted to check the flat and threaded cylindrical pin weld specimen's joint strength and hardness variation. The Electron backscattered diffraction (EBSD) analysis revealed that the average (Av.) grain size of the SZ region of the TCT and SQ pin are 3.74 µm and 5.64 µm, and the fraction of high angle grain boundaries are 0.560 and 0.368, respectively. The texture analysis of the SZ region revealed that the major availability of the shear texture component B/ B ̅ and C in the TCT pin weld specimen.