搭接中心距对电弧增材熔池流动及熔积层形貌影响的数值模拟

Numerical simulation of effect of overlapping distance on molten pool flow and deposited layer morphology of WAAM

搭接中心距对电弧增材搭接熔积的熔池流动及熔积层形貌有重要影响,为探究其影响机理,建立了钨极气体保护焊(Tungsten inert gas welding, TIG)电弧增材成形过程的三维数值模型,研究了不同搭接中心距对熔池流动及熔积层形貌的影响。结果表明:不同搭接中心距下熔池表面温度峰值相近,约为1900 K,表面流速呈非对称的双峰式分布。当搭接中心距小时,由于第一道焊道的支撑作用,使得第二道焊道横截面熔池流动和形貌不对称,熔池深而窄,熔池流动为单向的顺时针环流,左侧流速普遍大于右侧;随着搭接中心距的增大,第一道焊道的支撑作用逐步减弱,使得搭接焊道横截面熔池流动逐渐变为以第二道焊枪中心线为对称轴,左侧顺时针、右侧逆时针的两个环流,两侧流动逐渐对称,搭接熔池宽度逐渐增大、深度逐渐减小,两焊道逐渐分离并出现波谷,当搭接中心距为6 mm时熔积层形貌最平整。模拟与试验结果基本吻合,本研究结果可为电弧增材工艺参数调控提供理论支撑。

The overlapping distance has important influence on the molten pool flow and the morphology of the deposited layer in the wire arc additive manufacturing(WAAM).To explore its influencing mechanism,a three-dimensional numerical model of the forming process of tungsten inert gas welding(TIG)arc additives was established.The influence of different overlapping distances on the molten pool flow and the morphology of the deposited layer was studied.The results show that the peak temperature on the surface of the molten pool is similar under different overlapping distances,about 1900 K,and the surface flow velocity exhibits an asymmetric bimodal distribution.When the overlapping distance is small,due to the support effect of the first weld bead,the flow and morphology of the second weld bead’s cross section molten pool are asymmetric,the molten pool is deep and narrow,the flow of the molten pool is unidirectional clockwise circulation,and the flow velocity on the left side is generally greater than that on the right side.With the increase of the overlapping distance,the supporting effect of the first weld bead gradually weakens,causing the flow of the molten pool in the cross-section of the overlapping weld bead to gradually become symmetrical with the centerline of the second welding gun as the axis of symmetry,with two clockwise and counterclockwise circulations on the left and right sides.The flow on both sides gradually becomes symmetrical,the width of the overlapping molten pool gradually increases,and the depth gradually decreases.The two weld beads gradually separate and have troughs.When the overlapping distance is 6 mm,the morphology of the deposited layer is the smoothest.The simulation results are in good agreement with the experimental results,and the results of this study can provide theoretical support for the control of arc additive manufacturing process parameters.