焊接熔池凝固过程组织演变模拟

以枝晶生长动力学和晶粒生长能量最小原理为基础,建立了宏观传热与微观传质、形核、生长相耦合的焊接熔池CAMC晶粒生长二维数学模型.模型以CA方法模拟晶粒生长主干,MC在内部辅助晶粒生长以体现枝晶分枝机制,同时考虑非均匀形核对熔池结晶的影响因素,模拟了焊接熔池组织形成过程.结果表明,CAMC模型能够定量地描述熔池晶粒数目、尺寸和形貌演变,可以较准确地反映焊接熔池微观组织结构和熔池凝固过程中晶粒择优生长、柱状晶向等轴晶转换等物理机制.

Simulation of microstructure formation during solidification in weld pool

Base on the kinetics of the dendritic tip growth and least energy of grain growth theory,a two-dimension CAMC (Cellularautomata-Monte Carlo) grain growth mathematical model for weld pool which couples macroscopic heat transfer with microscopic solute transfer,nucleation and growth is developed.The skeleton of grain is formed by using CA model,and then the growth of grain is corrected by MC model.In the model,the mechanism and influencing factors of heterogeneous nucleation,which occurs at the boundary of welding zone,are taken into account.The dynamic process of microstructure formation in welding zone is presented.The evolution of amount,dimension and appearance of grains can be described quantitatively by using CAMC model,and the choosing growth of grain and the transition from columnar to equiaxed crystal can be exhibited by model.It is successful to simulate the microstructure evolvement during metal solidification of welding zone by CAMC model.