Epitaxial columnar grain growth is a prevalent microstructural feature in the additive manufacturing (AM) of metal components such as Inconel, with cubic unit cell crystal lattice structure (face centered cubic (FCC) or body centered cubic (BCC)). These columnar grains evolve from the partly molten grains in the substrate or the solidified metal. This work proposes an efficient model to simulate the competitive growth of epitaxial columnar dendritic grains. The proposed model tracks the dynamic changes in the dendrites emanating from discrete points along the solid/liquid interface of a quasi-steady melt pool (MP). These dynamic changes include convergence and divergence of growing dendrites. The model is extended to predict the microstructure of large 3D parts and experimentally validated by comparing the simulation results for laser powder bed fusion (L-PBF) and wire-arc additive manufacturing (WAAM) processes. The microstructure and pole figures are predicted for Inconel 718 samples produced by L-PBF and Inconel 740H samples produced by WAAM processes. The model predictions compare well with the observed microstructure and pole figures results for both the L-PBF and WAAM processes.

外延柱状晶粒生长是具有立方晶胞晶格结构（面心立方（FCC）或体心立方（BCC））的金属成分（如因科镍合金）的增材制造（AM）中普遍存在的微观结构特征。这些柱状晶粒从基材或凝固的金属中的部分熔融晶粒中析出。这项工作提出了一个有效的模型来模拟外延柱状树突状晶粒的竞争性生长。拟议的模型跟踪沿准稳态熔池（MP）的固/液界面离散点散发的树枝状晶体的动态变化。这些动态变化包括生长的树突的收敛和发散。该模型可扩展以预测大型3D零件的微观结构，并通过比较激光粉末床熔合（L-PBF）和线弧增材制造（WAAM）工艺的仿真结果进行实验验证。预测了L-PBF生产的Inconel 718样品和WAAM工艺生产的Inconel 740H样品的微观结构和极图。该模型预测与L-PBF和WAAM工艺的观察到的微观结构和极图结果均具有很好的对比。