The selective laser melting (SLM) process is an additive manufacturing technique that can fabricate three-dimensional workpiece by laser scanning and sintering of designated material in powder form on a preset scanning route along a bed of powders. This process involves a moving laser heating source which causes local transient mass and heat transfer with phase change, i.e., melting and solidifying, in a pool of melted powders. To fully investigate such a complicated transport process with reasonable computation cost, a novel quasi-transient numerical model (hopping model) was proposed and validated experimentally in this study. This approach includes a volumetric heat source defined as an elliptical Gaussian laser spot which hops along the scan path. Inconel 718 (IN718) superalloy powder is selected as the material for demonstration. Thermal analysis was carried out using a number of laser power and scan speeds in the range from 80 W to 120 W and from 80 mm/s to 140 mm/s, respectively. The comparison of molding appearance of the work pieces from the developed hopping model, full transient model, effective-transient model, and experiments illustrates the accuracy and the efficiency of the proposed hopping model. Molding appearance obtained from the quasi-transient model was consistent with experimental results with a relative error of less than 1.71% on the width of the IN718 stripes fabricated by SLM. For the cases analyzed in the current study, the quasi-transient model showed a 99% and a 60% reduction in both the computation time and the amount of computer memory needed compared to the full transient model and the effective-transient model, respectively. This novel quasi-transient simulation technique can be used to rapidly and effectively optimize process parameters for intelligent additive manufacturing.

选择性激光熔化（SLM）工艺是一种增材制造技术，可以通过激光扫描和沿粉末床的预设扫描路径烧结粉末形式的指定材料来制造三维工件。该过程涉及移动的激光加热源，该移动的激光加热源在熔融粉末池中引起具有相变的局部瞬态质量和热传递，即，熔融和凝固。为了以合理的计算成本充分研究这种复杂的运输过程，提出了一种新的准瞬态数值模型（跳跃模型）并在实验中进行了验证。此方法包括一个体积热源，该体积热源定义为沿着扫描路径跳跃的椭圆形高斯激光点。选择Inconel 718（IN718）超级粉末作为演示材料。使用多种激光功率和扫描速度分别在80 W至120 W和80 mm / s至140 mm / s的范围内进行热分析。通过开发的跳变模型，全瞬变模型，有效瞬变模型和实验对工件的成型外观进行了比较，说明了所提出的跳变模型的准确性和效率。从准瞬态模型获得的成型外观与实验结果一致，相对误差由SLM制造的IN718条带的宽度小于1.71％。对于当前研究中分析的案例，与完全瞬态模型和有效瞬态模型相比，准瞬态模型的计算时间和所需的计算机内存量分别减少了99％和60％。