Analysis of molten metal fluid flow mechanisms in variable polarity plasma arc welding of aluminum alloys
Analysis of molten metal fluid flow mechanisms in variable polarity plasma arc welding of aluminum alloys
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DOI：
10.1063/5.0165380
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发表时间：
2023-09
影响因子：
4.6
通讯作者：
Jingbo Liu;F. Jiang;Shujun Chen;Bin Xu;Guokai Zhang
中科院分区：
文献类型：
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作者：
Jingbo Liu;F. Jiang;Shujun Chen;Bin Xu;Guokai Zhang
变极性等离子弧焊接的稳定性和焊接质量取决于熔池内流体的定向流动。在这项研究中，采用粒子跟踪方法，获得流动的轨迹和速度的熔融金属的小孔壁使用高速摄像系统。此外，共聚焦激光扫描显微镜被用来捕捉3D形态的锁孔，而通过切片获得的流动通道。通过将流动轨迹和速度与3D小孔形态相关联，实验结果揭示了小孔前壁和后壁上存在鞍点。前鞍点表示深度方向上的流速最小的区域，导致小孔前侧向上和向下会聚。流到键孔侧壁的流体的深度和体积由该前鞍点确定。另一方面，后鞍点位于熔池的中心，标志着熔融金属最终到达的小孔后壁的入口侧和出口侧。后沉降点的位置将影响焊接状态。在焊接过程中，双鞍点的熔池保持动态稳定，其位置受到剪切力，重力，电弧压力，小孔形态，和流动通道。这些研究结果有助于控制稳定焊接的熔池中的小孔所需的工艺特性。
The stability and quality of welding in variable polarity plasma arc welding are determined by the directional fluid flow within the molten pool. In this study, the particle tracking method was employed to obtain flow traces and velocity of the molten metal on the walls of the keyhole using a high-speed camera system. Additionally, a confocal laser scanning microscope was utilized to capture the 3D morphology of the keyhole, while the flow channels were obtained through sectioning. By correlating the flow traces and velocity with the 3D keyhole morphology, the experimental results revealed the presence of saddle points on both the front and rear walls of the keyhole. The front saddle point represents the region where the flow velocity in the depth direction is minimum, causing the keyhole front side to converge upward and downward. The depth and volume of fluid flow to the keyhole sidewall are determined by this front saddle point. On the other hand, the rear saddle point is located at the center of the molten pool, marking the entry and exit sides of the keyhole rear wall where the melting metal eventually reaches. The location of the post-settlement point will affect the weld state. During the welding process, the double saddle points of the molten pool remain dynamically stable, and their position is influenced by shear force, gravity, arc pressure, keyhole morphology, and flow channels. These findings contribute to controlling the process characteristics necessary for stable welding of the keyhole in the molten pool.