Mechanical and Abrasive Wear Properties of Friction Stir Welded Joints of Aluminum Alloy AA6061-T6 with/Without Nickel Coating

The purpose of this work is to examine the microstructure, mechanical and sand abrasive properties of friction stir welded joints of aluminium alloy AA6061-T6 with and without nickel coating. A total eighteen samples, six samples of AA6061-T6 plates, six samples of 10 μm thick Ni coated AA6061-T6 plates and six samples of 15 μm thick Ni coated AA6061-T6 plates were friction stir welded by using different tool rotation speed (710 rpm, 1000 rpm, 1400 rpm) and different welding speed (28 mm/min, 56 mm/min). The joints manufactured using 1400 rpm tool rotation speed and 56 mm/min welding speed generated the highest tensile strength and percent elongation with joint efficiency of 69.05% with 15 μm Ni-coated AA6061-T6 plates and joints manufactured from 10 μm Ni-coated AA6061-T6 plates using 1000 rpm tool rotation speed and 28 mm/min welding speed generated the highest impact energy and higher hardness in NZ compared to the other joints. The 15 μm Ni-coated AA6061-T6 plates exhibited better abrasive wear resistant properties than the 10 15 μm Ni-coated plates. Microstructure investigation showed the precipitate size variations and their distributions and after friction stir welding, these precipitates became slightly coarser in the HAZ but finer in the nugget region.