为研究选区激光熔化Al-Mg-Sc-Zr合金的温度场和应力场,建立三维有限元分析模型.在考虑粉末-固体转变、材料热物理性能参数随温度变化、相变潜热和熔池对流的基础上,研究激光功率、点间距和扫描间距对温度场分布、熔池尺寸和残余应力场分布的影响.然后,采用实验法探讨激光功率、点间距和扫描间距对合金组织、相对密度和硬度的影响.结果表明:随着激光功率增大、点间距减小和扫描间距的减小,熔池尺寸逐渐增大.残余应力主要分布在第一个扫描道次的中间以及每一个扫描道次的起点和终点.实验结果证明有限元模拟的有效性.随着激光功率增大、点间距减小和扫描间距减小,试样的致密度先增大后减小.试样的最佳工艺参数区间为激光功率325～375 W、点间距80～100μm和扫描间距80μm.“,”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.