Abstract:A 3D finite element model was established to investigate the temperature and stress fields during the selective laser melting process of Al-Mg-Sc-Zr alloy. By considering the powder-solid transformation, temperature- dependent thermal properties, latent heat of phase transformations and molten pool convection, the effects of laser power, point distance and hatch spacing on the temperature distribution, molten pool dimensions and residual stress distribution were investigated. Then, the effects of laser power, point distance and hatch spacing on the microstructure, density and hardness of the alloy were studied by the experimental method. The results show that the molten pool size gradually increases as the laser power increases and the point distance and hatch spacing decrease. The residual stress mainly concentrates in the middle of the first scanning track and the beginning and end of each scanning track. Experimental results demonstrate the accuracy of the model. The density of the samples tends to increase and then decrease with increasing laser power and decreasing point distance and hatch spacing. The optimum process parameters are laser power of 325-375 W, point distance of 80-100 μm and hatch spacing of 80 μm.

Key words: aluminum-magnesium alloy; Al-Mg-Sc-Zr alloy; selective laser melting; finite element analysis; temperature field; stress field