Effect of construction angles on microstructure and mechanical properties of AlSi10Mg alloy fabricated by selective laser melting

Highlight• Seven AlSi10Mg alloys with different construction angles were prepared and researched. • The grains in vertical planes change from columnar grains to irregularly arranged grains, and then to equiaxed grains. • The AlSi10Mg exhibites mechanical property anisotropy that is a result of grain structure, dispersed Si, and residual stress. In this study, seven AlSi10Mg bulks with different construction angles (0°, 15°, 30°, 45°, 60°, 75°, and 90°) were fabricated by selective laser melting (SLM). The effects of different construction angles on the microstructure and mechanical properties of AlSi10Mg alloys were investigated. Increasing the construction angle changed the laser track segments from an ellipse to a semi-ellipse and then to fish-scale, specifically again from a semi-ellipse to an ellipse, due to the decrease of the laser radiation area. Meanwhile, the grains in the vertical planes changed from columnar grains to irregularly arranged grains, and then to equiaxed grains. The 45° sample exhibited the highest hardness of 154.44 HV_0.1. The 60° sample had a good combination of strength and plasticity with a tensile strength of 463.54 MPa, yield strength of 283.37 MPa, and elongation of 9.25%. The observed mechanical property anisotropy of the current AlSi10Mg alloy was a result of the pores, equiaxed grain structure, ultra-fine equiaxed sub-grains, and working hardening. In addition, the difference in the sample microstructures was attributed to the construction angles and deposited layer area.