Ti-45Al合金焊接熔池凝固过程数值模拟

采用元胞自动机法和有限差分法建立了宏微观耦合下的焊接熔池微观组织凝固模型，对Ti-45Al合金焊后凝固过程中的枝晶生长形貌和溶质场浓度分布进行模拟,并通过试验对模拟结果进行验证. 讨论分析了焊接热输入、内部形核数和表面传热系数对枝晶生长及形貌的影响. 结果表明，熔池内的组织主要由柱状晶和等轴晶两种形态组成. 热输入的增加和传热系数的减少均有助于柱状晶的生长，而内部形核数越大则越有利于等轴晶的生长. 所建立模型的计算结果与试验结果在关于枝晶生长的定向研究中有较好吻合.

Numerical simulation of solidification process of Ti-45Al alloy weld pool

The macro-micro model of molten pool solidification structures, which combined cellular automaton method and finite difference method, was developed and used to simulate the dendrite growth morphology as well as the solute concentration distribution during the solidification process of Ti-45Al alloy molten pool. And then the simulation results were validated by experiment. The effect of welding heat input, internal nucleation density and surface heat transfer coefficient on dendritic growth and morphology were discussed. The results indicated that the microstructures of molten pool were mainly composed of columnar and dendrite crystals. The higher heat input and lower surface heat transfer coefficient were beneficial to the growth of columnar crystals, while the larger the internal nucleation density, the more equiaxed crystals generated in the solidified molten pool. The simulation results of dendritic growth were in good agreement with that of the experimental results.