Effect of Reinforcement Particles on Friction Stir Welded Joints with Scarf Configuration: an Approach to Achieve High Strength Joints

The present research paper deals principally with the aim to achieve high strength through combined effect of incorporation of reinforcement particles in Friction stir scarf welded joints. The idea is implicated on AA6061-T6 plates with scarf angles of 60° and on different volume fraction (vol%) of reinforcement particles. A double pass FSW was performed using a taper threaded tool at a rotating speed (TRS) of 1100 rpm, a travel speed (TTS) of 2 mm/s, and a tool tilt angle (TTA) of 2°. The current study’s goal is to investigate the macrostructure and microstructure development, as well as the joint’s mechanical properties. The optical microscopy reveals fine, recrystallized and equiaxed grain in the nugget zone (NZ) due to the pinning effect of reinforcement particles. It has been observed through the scanning electron microscopy that higher grain refinement along with homogeneous distribution of SiC particles were achieved in multi-pass as compared to single pass. There is also strong bond formed between the aluminium matrix and the reinforcing particle. Moreover, it has been observed that when the vol% of reinforcement increases, the hardness and ultimate tensile strength (UTS) values improves while the % elongation decreases. The UTS has found to be increased by 12 % at 15 vol% of reinforcement. All tensile specimens failed outside the NZ with ductile fracture during tensile testing.