Microstructure and mechanical properties of laser metal deposited AlSi10Mg alloys

Thin-walled specimens with more than 150 layers were deposited by laser metal deposition without cracks and concaving deformation. The microstructure in each layer could be divided into three zones according to the morphology. The homogeneity deteriorated with the rising of the input. The tensile strength dropped 29.7% when the porosity increased from 0.53% to 1.88%. Controlling the oxygen under 0.5% and optimising the heat input, the as-built tensile strength reached 360 MPa. The fracture elongation was enhanced from 3.9% to 12.7% when the heat input was increased from 480 to 1200 W. The decrease of the secondary dendrite arm spacing and the change of fracture mechanism is the main reason leading to the strengthening of the mechanical properties.