Abstract:

Through analyze the MIG groove welding process and the welding experimental result, the physical process of 3D welding was simplified as a two dimensional mathematical model. For mathematical model establishment, based on the analysis of experimental results, established a two-dimensional mathematical model of welding seam section welding physical process. This model included the welding heat source model and molten pool phase change flow CFD model. The moving Gauss heat source model was used to describe the heat effect of arc and workpiece. By introducing scalar of liquid fraction, mushy region dynamic character which was described using "Darcy" model proposed for porous media, and phase change which was taken into account using source-based method, new CFD model was established to simulate transient heat and mass transfer phenomena in welding process. Comparative analysis the numerical simulation result and the metallographic figure, corrected the moving gauss heat source model parameters. Analyze the molten pool shape influenced by thermal buoyancy and Marangoni force in CFD model. Through comparative analysis the results of numerical simulation and experimental, verified the accuracy of the mathematical model. A further discussion on Gauss heat source parameters and the driving force mechanism model of molten pool flow was made. Results showed that through the reasonable model parameters selection, two-dimensional mathematical model can accurate analysis the evolution of V groove molten pool during MIG welding.

Key words: MIG welding, welding pool, V groove, Marangoni flow, numerical simulation, interfacial tension, model

摘要：

通过对MIG坡口焊接工艺过程的分析将三维焊接物理过程简化为二维数理模型，建立移动高斯热源模型用于描述电弧与工件的热作用，建立熔池内的CFD模型用以描述熔池内熔化／凝固过程的流动传热传质现象，对典型V型坡口焊接过程进行实验和数值模拟研究，通过与实验得到的工件截面金相图对比分析验证了数理模型的准确性，最后对数理模型中高斯热源参数及熔池流动的驱动力机理模型进行了进一步讨论。结果表明通过合理的模型参数选择二维数理模型可以准确地分析MIG坡口焊过程熔池的演变过程。

关键词: MIG焊, 熔池, V型坡口, Marangoni流, 数值模拟, 界面张力, 模型