通过模拟仿真与实验结合研究粉末粒径对选区激光熔化(SLM)可加工性的影响。以3种粒径AlSi10Mg粉末为对象，基于离散元和流体力学数值模拟方法研究SLM铺粉和粉末熔化/凝固介观行为，并对成形样品进行宏观成形质量检测。结果表明，铺粉过程中，粒径小于20 μm的粉末剧烈团聚形成大量空隙，粒径大于53 μm粉末易形成少量大的空隙，中等粒径粉末床相对密度比细粒径和大粒径分别高7.69%和3.17%。单层粉末床熔融时，铺粉质量不均匀，细粒径与粗粒径熔道不规则。但经历多层熔化后，细粒径熔道缺陷部分缓解。随着粒径的增加，熔道表面平整度下降，细粒径粉末样品存在较多孔隙，粗粒径粉末存在少量未熔合缺陷。中等粒径粉末SLM可加工性最好，样品相对密度达到99.8%，比细粒径和粗粒径分别高1.4%和0.4%。

Selective laser melting (SLM) is a widely used high-precision additive manufacturing technology that can achieve arbitrarily complex structures. The powder size used by SLM is generally 15-53 μm, which is suitable for manufacturing parts with a forming accuracy within tens of microns. However, the reason why smaller or larger particle size powders are not suitable is not yet clear. The effect of particle size on SLM processability was studied by simulation and experimentation. Three powder particle sizes of AlSi10Mg were used to study the behavior of powder spreading and melting/solidification during SLM by discrete element and computational fluid dynamics methods, respectively. The macroscopic forming quality of the formed samples was tested. The results show that the powders with a particle size below 20 μm agglomerate vigorously to form many cavities, and the powders with a particle size above 53 μm tend to form few large cavities. The relative density of the powder bed with the medium particle size is 7.69% and 3.17% higher than those of the fine and large particle sizes, respectively. The melt channels of the fine and coarse particle sizes are irregular due to the uneven quality of powder laying when the powder bed is melted. However, after multilayer melting, defects in the melt channel of the fine particle size are partially alleviated. With the increase in particle size, the melt channel surface flatness decreases, the fine particle size powder samples have more porosity, and the coarse particle size powder has a few unfused defects. The processability of the medium particle size for SLM is the best among them. The relative density of the sample with the medium particle size reach 99.8%, which is 1.4% and 0.4% higher than those of samples with fine and coarse particle sizes, respectively.