In this research, using submerged friction stir processing (SFSP) method to produce Al6061-Al2O3 surface nanocomposite and its characterization was investigated. For this purpose, after optimizing FSP machine, special tool and SFSP parameters by using artificial neural networks (ANN) model, SFSP was applied underwater as the cooling media on an extruded nanocomposite strip that had been embedded into a grove on Al6061-T6 sample. Measurement of temperature showed that using cooling media can decrease temperature of process up to 100°C and it can produce a sound stir zone. Microstructure of the stir zone, thermo-mechanical affected zone and base metal was studied using optical microscopy and Scanning electron microscopy. Investigation of mechanical properties consisted of average hardness of stir zone. Wear behavior of samples was investigated using wear sliding machine at ambient temperature and 400°C. Results indicated that, using reinforcement Al2O3 nano particles can not improve wear behavior of specimens at room temperature. On the other hand, wear test at 400°C on nanocomposite specimen showed higher wear properties in comparison with base metal and SFSP samples. In this test depth of wear path in nanocomposite, SFSP and base metal specimens were 0.36mm, 1.97mm and 1.63mm respectively.
