Friction Stir Welding of AA6082 Thin Aluminium Alloy Reinforced with Al₂O₃ Nanoparticles

In this present investigation, AA6082-T6 thin aluminium alloy plates of 2 mm thickness were friction stir welded using fine ceramic Al₂O₃ nanoparticles as the reinforcing materials between the adjoining plates. The joining was done by hexagonal pin profile tool of tungsten carbide material with tool rotational speeds 710 rpm and 900 rpm. The number of passes of the welds was 2 and 3 with constant tool traverse speed of 40 mm/min. Microstructural study was done by employing an optical microscope and electron microscopy. The microstructural results show that the weld produced with tool rotational speed of 710 rpm, tool traverse speed of 40 mm/min and the number of passes 3 has the good distribution of the alumina nanoparticles in the stir zone leading to grain refinement. The reinforced sample welded with 3 passes achieved the highest average grain size number of 16.02 and highest ultimate tensile strength of 227.61 MPa, yield strength of 154.9 MPa and elongation percentage of 10.5%. The reinforcement-included welded sample exhibited highest hardness value of 74 Hv in the weld nugget zone. (author)