In this study, a coupled transient thermomechanical finite element model is developed to examine the laser powder bed fusion (L-PBF) process of the Inconel 718 (IN718) and Oxide Dispersion Strengthened (ODS) superalloys (ODS-IN718). The linear isotropic elastic perfectly plastic constitutive model is implemented for the mechanical part whereas all the thermophysical properties are defined as fully temperature dependent. This new model enables three states of the metal including powder, liquid, and solid phases in the continuum-based finite element simulations. Besides, it can meticulously simulate multi-layered samples to assess thermomechanical performance and residual stress between layers. First, benchmark problems are revisited to verify the high accuracy of the present model for predicting transient temperature profile and residual stress accumulation. Then, thermomechanical analysis of a single-track three-layer test case is performed to investigate the L-PBF process of IN718 and ODS-IN718 samples for various laser powers and scan speeds. Also, the thermal characterization of ODS-IN718 samples is experimentally conducted. It is demonstrated that the numerical melt pool dimensions provide good agreement with experiments with an average error of 17% for melt pool dimensions. Moreover, mechanical results reveal that high tensile residual stresses accumulate in the middle part of the track. The manufacturing quality of the IN718 and ODS-IN718 samples are comprehensively compared based on the variations of stress distribution at different layers for different laser scan speeds. Also, the optimal laser scan speed is achieved to minimize the residual stresses for the ODS-IN718 alloy. Overall, ODS-IN718 has a lower residual stress than IN718 especially at lower laser scan speeds due to the enhanced thermomechanical behavior attributed to the change in material properties due to the presence of dispersed particles.

在本研究中，开发了一个耦合瞬态热机械有限元模型，以检验 Inconel 718 （IN718） 和氧化物色散强化 （ODS） 高温合金 （ODS-IN718） 的激光粉末床熔融 （L-PBF） 工艺。线性各向同性弹性完全塑性本构模型用于机械部分，而所有热物理特性都定义为完全依赖于温度。这个新模型在基于连续体的有限元仿真中支持金属的三种状态，包括粉末、液相和固相。此外，它可以细致地模拟多层样品，以评估热机械性能和层间残余应力。首先，重新审视基准问题，以验证当前模型在预测瞬态温度曲线和残余应力累积方面的高精度。然后，对单轨三层测试用例进行热机械分析，以研究 IN718 和 ODS-IN718 样品在各种激光功率和扫描速度下的 L-PBF 工艺。此外，ODS-IN718 样品的热表征也通过实验进行。结果表明，数值熔池尺寸与熔池尺寸平均误差为 17% 的实验具有良好的一致性。此外，机械结果表明，高拉伸残余应力在轨道的中部积累。根据不同激光扫描速度下不同层的应力分布变化，对 IN718 和 ODS-IN718 样品的制造质量进行了综合比较。此外，还实现了最佳的激光扫描速度，以最大限度地减少 ODS-IN718 合金的残余应力。 总体而言，ODS-IN718 的残余应力低于 IN718，尤其是在较低的激光扫描速度下，因为由于分散颗粒的存在导致材料性能的变化导致了热机械行为的增强。