镁合金冷金属过渡熔池动态行为数值模拟  

Numerical simulation of dynamic behavior of magnesium alloy cold metal transition molten pool

作　　者：何俊杰[1] 马瑞杨 王天琪[1] HE Junjie;MA Ruiyang;WANG Tianqi(Tianjin Key Laboratory of Modem Mechatronics Equipment Technology(Tiangong University),Tianjin 300387,China)

机构地区：[1]天津市现代机电装备技术重点试验室(天津工业大学),天津300387

出　　处：《材料科学与工艺》2022年第5期18-26,共9页Materials Science and Technology

基　　金：国家自然科学基金资助项目(51975410);天津市科技计划项目(19YFZCGX00870);天津市科技特派员项目(20YDTPJC00780);天津市“项目+团队”重点培养专项资助(XC202053);天津市教委科研计划项目(2019KJ011)。

摘　　要：为研究冷金属过渡焊(CMT)的周期性能量输入及焊丝抽送行为对镁合金熔池动态行为的影响,在FLUENT软件中建立了焊丝-熔滴-熔池多相流数值分析模型。提出一种在流体体积法(VOF)多相流计算域中划分熔滴与熔池区域并判断其接触状态的方法,结合动网格技术实现自动响应的焊丝抽送,在熔池区域加载间歇性的热源、电弧力,采用镁合金CMT堆焊实验所得参数进行数值模拟。结果表明,在CMT能量输入周期的短路阶段,由于焊丝的回抽,熔池被向上提拉并在焊丝端部形成了液桥,内部液态金属在马兰戈尼力的作用下,由边缘流向中间,由下方流向上方,焊丝持续回抽至脱离熔池后,熔池受到液桥断裂的反作用力,液态金属快速向后方流动使熔池形状发生改变,可知焊丝回抽与马兰戈尼力是熔池动态行为的主导作用力,此外,焊缝熔深的模拟结果为0.53 mm,与实际成形焊缝的熔深存在3.47%的误差,验证了模型的有效性。To study the effects of periodic energy input and wire pumping of cold metal transition(CMT) welding on the dynamic behavior of magnesium alloy molten pool, a numerical analysis model of wire-droplet-molten pool multiphase flow was established by using FLUENT software. A method was proposed to divide the regions of droplet and pool and judge their contact states in the multiphase flow calculation domain of fluid volume method(VOF). Combined with the dynamic grid technology, the automatic response of welding wire pumping was realized. Heat source and arc force were applied intermittently to the molten pool. Parameters obtained from CMT welding experiment of magnesium alloy were adopted for numerical simulation. Results show that in the short circuit stage of energy input period of CMT, due to wire redrawing, the molten pool was lifted and liquid bridge was formed at the wire end. The internal liquid metal flowed from the edge to the middle and the bottom to the top under Marangoni force. The wire was continuously redrawn until separated from the pool. At the time, the pool was subject to the counterforce of the liquid bridge fracture, and the liquid metal quickly flowed backwards, which changed the shape of the pool. Wire redrawing and Marangoni force were the dominant acting force of the dynamic behavior of molten pool. Besides, the simulated welding pool depth was 0.53 mm, an error of 3.47% with actual formed welding pool depth, which verified the effectiveness of the proposed model.

关 键 词：镁合金焊接 冷金属过渡 多相流 数值模拟 传热传质 

分 类 号：TG457.19[金属学及工艺—焊接]