Dynamic behaviors of molten pools during active laser welding of thick 304 stainless steel plates are monitored in real time by utilizing a high-speed camera system. The effects of various active fluxes on the dynamic variations of molten pools are analyzed, and the results are compared with the uncoated specimens. The research reveals that all the molten pools present periodic variations. Among them, the specimen coated with NaF active flux exhibits the shortest cycle of molten pool change, with a single cycle duration of approximately 0.5 s. The specimen coated with TiO₂ active flux exhibits the longest cycle of molten pool change, and the single cycle duration is around 1.1 s. Moreover, the molten pools also show varying widths. The maximum molten pool width is found with the specimen coated with CeO₂ active flux, whose value is 3.277 mm. Meanwhile, the minimum molten pool width is found with the specimen coated with NaF active flux, whose value is 1.799 mm. In addition, the coating of active fluxes also produces certain effects on molten pool stability. The specimen coated with NaF active flux presents intense emission of metal vapor during welding, drastic oscillation of the molten pool, and severe spattering of metal particles. Contrastively, the molten pool of the specimen coated with Cr₂O₃ active flux is rather stable. In conclusion, by selecting an appropriate active flux, the cycle of molten pool variation can be prolonged, the pool stability can be enhanced, and the occurrence of spattering and other defects can be suppressed.

中文翻译：

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不同活性焊剂对激光焊接厚不锈钢板熔池行为的影响

利用高速摄像系统实时监控厚 304 不锈钢板主动激光焊接过程中熔池的动态行为。分析了各种活性助熔剂对熔池动态变化的影响，并将结果与​​未涂层试样进行了比较。研究表明，所有熔池都呈现周期性变化。其中，涂有NaF活性助熔剂的试样表现出最短的熔池变化周期，单周期持续时间约为0.5 s。涂有TiO ₂活性助熔剂的试样表现出最长的熔池变化周期，单周期持续时间约为1.1 s。此外，熔池也显示出不同的宽度。最大熔池宽度是在涂有 CeO 的试样上找到的₂有效通量，其值为 3.277 mm。同时，最小熔池宽度是在涂有 NaF 活性助熔剂的试样上发现的，其值为 1.799 mm。此外，活性熔剂的包覆对熔池稳定性也产生一定的影响。涂有 NaF 活性助焊剂的试样在焊接过程中会出现强烈的金属蒸气排放，熔池剧烈振荡，以及金属颗粒的严重飞溅。相比之下，涂有Cr ₂ O ₃活性助熔剂的试样的熔池相当稳定。综上所述，通过选择合适的活性助熔剂，可以延长熔池变化周期，增强熔池稳定性，抑制飞溅等缺陷的发生。