Elucidation of the weld pool convection and keyhole formation mechanism in the keyhole plasma arc welding
Elucidation of the weld pool convection and keyhole formation mechanism in the keyhole plasma arc welding
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DOI：
10.1016/j.ijheatmasstransfer.2018.11.108
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发表时间：
2019-03
影响因子：
5.2
通讯作者：
Dongsheng Wu;Anh Van Nguyen;S. Tashiro;Xueming Hua;Manabu Tanaka
中科院分区：
文献类型：
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作者：
Dongsheng Wu;Anh Van Nguyen;S. Tashiro;Xueming Hua;Manabu Tanaka
建立了考虑自适应热源、等离子体流动产生的剪切应力和上下表面变形的电极-电弧模型和三维熔池模型，研究了锁孔等离子弧焊中熔池对流和锁孔形成机理。借助x射线透射系统、高速摄像机和热成像仪，对熔池的流体流动和温度分布进行了研究。数值和实验结果表明：穿透小孔形成后，熔池内部形成两个对流涡流。熔液在熔池的上表面向后流动，在熔池的下表面向下向后流动。高电弧压力和等离子体剪切应力引起的强流体流动和能量输送是熔池低温分布的主要原因。电弧压力驱动焊池变形和剪切应力驱动焊池变形都是导致锁孔形成的原因，其中剪切应力驱动焊池变形的机制占主导地位。
An electrode-arc model, and a three dimensional weld pool model considering the self-adaptive heat source, the shear stress caused by plasma flow, and the deformation of the top and bottom surfaces, are developed to investigate the weld pool convection and keyhole formation mechanism in the keyhole plasma arc welding. With the help of the X-ray transmission system, high-speed video camera and thermal camera, the fluid flow and the temperature distribution of the weld pool are studied. The numerical and experimental results show that: after the penetrated keyhole formation, two convective eddies are formed inside the weld pool. The molten metal flows backward at the top surface of the weld pool, and flows downward and backward at the bottom surface of the weld pool. The low temperature distribution in the weld pool is attributed to the strong fluid flow and energy transportation caused by the much high arc pressure and plasma shear stress. Both the arc pressure driven weld pool deformation and shear stress driven weld pool deformation are responsible for the keyhole formation, and the first mechanism is especially dominant.