Effect of rotation speed on microstructure and mechanical anisotropy of Al-5083 alloy builds fabricated by friction extrusion additive manufacturing

Abstract

The final builds with multiple layers for a non-age-hardenable aluminum alloy were successfully fabricated under different rotation speeds using friction extrusion additive manufacturing, a force-controlled friction-based additive manufacturing process that allows the free design of the deposition path. The single layer thickness increased from 1.7 mm to 3.0 mm when the rotation speed was reduced from 800 r/min to 400 r/min for a given layer thickness of 4 mm. The grain size at the interface was refined to 3.8–5.0 μm at 800 r/min because less recrystallization occurred, resulting in a higher geometrically necessary dislocations density. The grains formed at the interface at 800 r/min were mainly determined by recrystallization textures Cube, CubeRD, and CubeND and deformation texture S. However, a stronger coupling effect between heat and plastic deformation at 600 r/min leads to the dominance of shear textures B/B‾ and RtCu and deformation textures S. The final deposits superior to the wrought Al alloy 5083-H112 in terms of tensile properties were obtained at 600 r/min due to the largest contribution of grain refinement strengthening. Grain refinement increases strength at the interface and interlayer by 113.1 MPa and 92.1 MPa, respectively. The tensile strength, yield strength, and elongation at break in the Z direction reach 290.2 MPa, 163.3 MPa, and 12.6%, respectively. Due to the existence of kissing bonding at 800 rpm, the value of the elongation at break in the Z direction is only 19% of the value in the X direction.