An investigation on application of friction stir additive manufacturing (FSAM) for the production of AA6061/TiC-graphene hybrid nanocomposite in the shape of multi-layer cylindrical part

In this research, Friction Stir Additive Manufacturing (FSAM) has been investigated for the production of AA6061/TiC-graphene hybrid nanocomposites. For this purpose, nanocomposites were produced in the shape of three-layer cylindrical parts by Friction Stir Deposition (FSD) of the AA6061 consumable rod with pre-placed reinforcement nanoparticles in it (0.25 wt%). TiC and graphene nanoparticles were chosen as the reinforcements for improving hardness and wear behavior in the additive manufactured parts, respectively. The nanocomposites were deposited with four different rotation speeds, including 1200, 1300, 1400, and 1500 rpm, under a continuous feeding speed of 25 mm/min. Also, a reference sample without any reinforcement was deposited for comparison with the nanocomposites. Appearance characteristics, microstructural specifications, hardness, wear behavior, and corrosion resistance were investigated for evaluation of the manufactured parts. FSAM led to the production of fine-grain nanocomposites (∼15–25 μm) with a relatively uniform distribution of the reinforcement nanoparticles. The addition of reinforcement nanoparticles caused improvements in hardness, wear rate, friction coefficient, and corrosion rate by about 42%, 66%, 15%, and 33%, respectively. In this regard, best-manufactured nanocomposite showed good hardness (71.5 HV), superb wear rate (260 × 10^-5 mg/N.m), low friction coefficient (0.697), and excellent corrosion rate (2.6 mpy). Finally, it was observed that performing FSD by increasing the tool rotation speed at a constant vertical speed resulted in nearly 10% grain growth and 45% dissolution of Mg-rich precipitates in the matrix. These microstructural evolutions decreased hardness (∼24%) and corrosion rate (∼50%), and increased wear rate (∼38%) and friction coefficient (∼16%) in the nanocomposites.