The discrete element method (DEM) and the finite volume method (FVM) were used to build a 3D numerical model to simulate the selective laser melting process (SLM). The Marangoni effect and the recoil pressure were incorporated in the model. Experiments for the single track were performed for verification. The numerical results indicated that melt tracks with different morphologies were formed when the same linear energy density (LED) was applied. The formation mechanism of the melt track defects including balling, porosity and distortion were analyzed. It was found that the balling defect was concluded to be resulted by insufficient energy input incapable of melting the substrate. The distortion defect originated from the combined effect of the random distribution of powder particles and the Marangoni effect. In the keyhole-mode laser melting process, the unsteady behavior of the molten pool and keyhole led to the porosity defect.

使用离散元方法（DEM）和有限体积方法（FVM）来构建3D数值模型，以模拟选择性激光熔化过程（SLM）。模型中包含了马兰戈尼效应和后坐力。进行了单轨实验以进行验证。数值结果表明，当采用相同的线性能量密度（LED）时，会形成具有不同形态的熔体轨迹。分析了熔痕缺陷的形成机理，包括滚珠，孔隙率和变形。已经发现，滚珠缺陷是由于不能熔化基板的能量输入不足而导致的。变形缺陷源自粉末颗粒的随机分布和马兰戈尼效应的综合作用。