We present the results of 3D modeling of the laser and electron beam powder bed fusion process at the mesoscale with an in-house developed advanced multiphysical numerical tool. The hydrodynamics and thermal conductivity core of the tool is based on the lattice Boltzmann method. The numerical tool takes into account the random distributions of powder particles by size in a layer and the propagation of the laser (electron beam) with a full ray tracing (Monte Carlo) model that includes multiple reflections, phase transitions, thermal conductivity, and detailed liquid dynamics of the molten metal, influenced by evaporation of the metal and the recoil pressure. The model has been validated by a number of physical tests. We numerically demonstrate a strong dependence of the net energy absorption of the incoming heat source beam by the powder bed and melt pool on the beam power. We show the ability of our model to predict the measurable properties of a single track on a bare substrate as well as on a powder layer. We obtain good agreement with experimental data for the depth, width and shape of a track for a number of materials and a wide range of energy source parameters. We further apply our model to the simulation of the entire layer formation and demonstrate the strong dependence of the resulting layer morphology on the hatch spacing. The presented model could be very helpful for optimizing the additive process without carrying out a large number of experiments in a common trial-and-error method, developing process parameters for new materials, and assessing novel modalities of powder bed fusion additive manufacturing.

我们使用内部开发的先进的多物理数值工具，对中尺度的激光和电子束粉末床融合过程进行3D建模，并给出了结果。该工具的流体动力学和导热系数核心基于格子Boltzmann方法。数值工具考虑了粉末颗粒在层中按尺寸的随机分布以及激光（电子束）在全光线跟踪（蒙特卡洛）模型中的传播，该模型包括多次反射，相变，热导率和精细受金属蒸发和后坐力影响的熔融金属的液体动力学。该模型已通过许多物理测试验证。我们从数值上证明了粉末床和熔池对进入的热源束的净能量吸收的强烈依赖关系。我们展示了我们的模型能够预测在裸露的基材以及粉末层上的单个轨迹的可测量属性的能力。我们对于多种材料的轨道深度，宽度和形状以及各种能源参数的实验数据都获得了很好的一致性。我们进一步将模型应用到整个层形成的模拟中，并证明所得层形态对舱口间距的强烈依赖性。提出的模型对于优化加成工艺非常有用，无需使用常见的试错法进行大量实验，为新材料开发工艺参数，