Abstract Establishing an open keyhole throughout work-piece is the key to penetrate work-piece fully in gas focusing plasma arc welding. In order to study heat transfer, metal flow and keyhole surface evolution in gas focusing plasma arc welding, the three dimensional mathematical model is developed. Arc heat model and plasma arc pressure model are used to describe heat and force action in gas focusing plasma arc welding. Temperature field, fluid flow in weld pool and keyhole evolution are simulated. It is found that metal in weld pool front flows bypass keyhole wall toward weld pool back. Center line of keyhole channel is crocked instead of going along z-axis. The calculated weld shape agrees with the experimental data basically. This work may enrich theoretical knowledge about the complicated thermal physical process and provide basic data to guide welding application in gas focusing plasma arc welding.

中文翻译：

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气体聚焦等离子弧焊熔池金属流动与小孔演化

摘要 在气体聚焦等离子弧焊中，在整个工件上建立一个开放的小孔是实现工件完全熔透的关键。为了研究气体聚焦等离子弧焊中的传热、金属流动和小孔表面演化，建立了三维数学模型。电弧热模型和等离子弧压力模型用于描述气体聚焦等离子弧焊中的热力作用。模拟了温度场、熔池中的流体流动和小孔演化。发现熔池前部的金属绕过锁孔壁流向熔池后部。锁孔通道的中心线被挤压而不是沿着 z 轴。计算出的焊缝形状与实验数据基本吻合。