Abstract:Using a friction stir additive manufacturing (FSAM) process, the fabrication of a two-layer aluminum- copper pipe was studied experimentally and numerically. For this purpose, by presenting a 3D thermo-mechanical model in ABAQUS software, the temperature and strain distributions during the process were studied. The simulation results show that, although the rotational-to-traverse speed ratio with a good approximation can predict the heat input during welding, it is not a precise measure to predict the occurrence of defects in the weld cross-section. There is a good agreement between the predicted and experimental thermal results, and the maximum relative error is 4.1% in estimating the maximum temperature during welding. Due to heat and severe plastic deformation in the stir zone, the aluminum-copper intermetallic compounds (CuAl₂ and Cu₉Al₄) are formed. The maximum hardness in the stir zone is 301.4 HV_0.1 in sample welded with an overlap of -0.5 mm. The ultimate tensile strength and elongation of the two-layer pipe fabricated by friction stir additive manufacturing are (319.52±2.31) MPa and 19.47%, respectively.

Key words: friction stir welding; thermo-mechanical simulation; two-layer Al-Cu pipes; microstructure; mechanical properties