【摘要】 焊接熔池冷却速度快、凝固时间短、过冷度大,结合以上特点构建相场法与有限差分的耦合数学模型,对TIG焊接熔池中等轴晶生长过程进行研究.首先,利用该模型成功模拟了纯镍焊接熔池中心区域单个等轴晶生长过程形态演变.进一步研究了不同过冷条件下,等轴枝晶生长形貌和生长行为的变化规律,模拟结果符合固液界面形貌稳定性理论.同时,初步计算了多晶粒竞争生长形态,计算结果清晰再现了不同晶粒间侧枝的竞争生长微观现象,为更深入的研究工作奠定了基础.更多还原

【Abstract】 A coupled model of phase field method and finite difference method was established to study equiaxed dendritic growth in the central area of TIG welded molten pool.In this model,some characteristics of welding pool,such as high cooling rate,short solidification time,and large undercooling degree were taken into consideration.Based on the model,simulation of single equiaxed grain growth in the molten pool of pure nickel was performed successfully.Moreover,the change of dendrite morphology and growth behavior with undercooling in welding pool was studied.The simulation results were in good accordance with the stability theory of interface.Meanwhile,the simulation of multiple grain growth was also presented,which reproduced the competitive growing behavior among side-branches.This study lays a good foundation for further research.更多还原