Zhang Yubin, Du Jun, Wang Huafeng, Li Hua, Zhao Xiaoyun
College of Digital Technology and Engineering, Ningbo University of Finance & Economics, Ningbo 315175, China.
Materials (Basel). 2021 May 7;14(9):2430. doi: 10.3390/ma14092430.
A transient three-dimensional (3D) numerical model was established to illustrate the heat transfer, fluid flow and particle migration behaviors in the molten pool during TIG-assisted droplet deposition manufacturing (DDM) of SiC particle-reinforced aluminum matrix composites (AMCs). The effect of temperature-dependent physical properties and the interaction between the SiC reinforcement and the liquid metal matrix were considered. A double-ellipsoidal volumetric heat source model was adopted to simulate the energy interactions between the pulse square-wave variable polarity TIG welding arc and the moving substrate. Free surface fluctuations of molten pool due to arc force and sequential droplet impact are calculated with volume of fluid (VOF) method in a fixed Eulerian structured mesh. The numerical model, capable of capturing the impact, simultaneous spread, and phase change of the droplets as well as the motion trajectory and terminate distribution state of the reinforcement particles, is key tool to understand the formation mechanism of the TIG-assisted DDM of SiC particle-reinforced AMCs. The numerical model was validated by the metallographic observations, and the calculated particle distribution and solidification morphology of deposited layer agree well with the experimental measurements.
建立了一个瞬态三维（3D）数值模型，以阐明在碳化硅颗粒增强铝基复合材料（AMC）的钨极惰性气体保护焊（TIG）辅助熔滴沉积制造（DDM）过程中熔池内的传热、流体流动和颗粒迁移行为。考虑了随温度变化的物理性质的影响以及碳化硅增强体与液态金属基体之间的相互作用。采用双椭球体体积热源模型来模拟脉冲方波变极性TIG焊接电弧与移动基板之间的能量相互作用。在固定的欧拉结构化网格中，用流体体积（VOF）法计算电弧力和连续熔滴冲击引起的熔池自由表面波动。该数值模型能够捕捉熔滴的冲击、同时铺展和相变以及增强颗粒的运动轨迹和最终分布状态，是理解碳化硅颗粒增强AMC的TIG辅助DDM形成机制的关键工具。通过金相观察对数值模型进行了验证，计算得到的沉积层颗粒分布和凝固形态与实验测量结果吻合良好。
