ULCB钢焊接熔池凝固过程数值模拟

采用元胞自动机法建立ULCB钢焊接熔池凝固过程的宏微观耦合模型,模拟非均匀温度场下焊接熔池凝固过程的组织形貌演变和溶质场分布,分析不同形核参数和合金成分对焊接熔池枝晶形貌的影响。结果表明,熔池边缘形成柱状晶,熔池中心形成等轴晶,柱状晶和等轴晶相互抑制长大;枝晶生长过程中始终存在着枝晶偏析现象;形核密度和合金成分影响枝晶的形核和生长,随着形核密度和合金成分的增加,焊缝中等轴晶区域增加,晶粒细化。

Numerical simulation of solidification process of molten pool in welding of ULCB steel

The coupling model of macro and micro of the molten pool in the welding of ULCB steel is established by cellular automaton,which simulates the evolution of microstructure and appearance and the distribution of solute field in the solidification process of molten pool in temperature field,analyses the effect of different nucleation parameters and alloy composition on the microstructure of dendritic crystal in molten pool.The results show that the columnar crystal forms in the edge of molten pool,the isometric crystal forms in the center of molten pool,these two kinds of crystal mutual inhibit growth;Dendritic segregation always exists in the growth process of dendritic crystal;Nucleation density and alloy composition influence the nucleation and growth of dendrite crystal,when the nucleation density and alloy composition increase,the medium isometric crystal region enlarges and the crystal grain refines.