Effect of Heat Treatment on the Anisotropic Mechanical Properties of AlSi10Mg Fabricated by Selective Laser Melting

In this paper, the effect of heat treatment on the anisotropic mechanical properties of AlSi10Mg formed by selective laser melting (SLM) was studied. AlSil0Mg alloy samples were formed by SLM horizontal and vertical orientation, and T6 heat treatment was performed on the samples. The phase composition, metallographic structure and fracture morphology of the samples were characterized, and the hardness and tensile properties were tested. Results show that the microstructure is obviously homogenized after heat treatment. The morphology of eutectic Si phase changes from the original network structure to irregular block and granular. For AlSi10Mg alloy formed by SLM with different orientations, the anisotropy of strength is quite different (>10%). The anisotropy of hardness is not obvious, and the strength and plasticity of the horizontal orientation forming sample are better. The strength of the samples formed in different orientations decreases and the plasticity increases after heat treatment. The strength anisotropy of different orientations is significantly reduced (<10%). Before heat treatment, the tensile fracture of AlSi10Mg alloy with different orientations is brittle fracture. The fracture morphology is mainly characterized by step and tear distribution. After heat treatment, the tensile fracture is ductile fracture. The fracture morphologies of vertical orientation and horizontal orientation are equiaxed dimples and shear dimples, respectively.