Abstract In this study, the dynamic behaviors of metal vapor, plasma, keyhole, and weld pool during activating laser welding of stainless steel thick plates are monitored in real time by employing a novel "sandwich" method in combination with a high-speed camera system. Meanwhile, the welding quality of specimens is inspected and analyzed from the aspects like joint weld formation, mechanical properties, microstructure, and element distribution. The effects of Cr2O3 active agent on the welding stability and quality of specimens are explored. According to the results, adequate coating of active agent on the specimen surface can weaken and suppress the generation and drastic changes of metal vapor and plasma inside and outside the keyhole, increase the keyhole depth, improve the keyhole shape, weaken the oscillation amplitude of weld pool, and prolong the change cycles of keyhole and weld pool. Consequently, the stability of welding process is enhanced, the generation of porosity and splash defects is inhibited preferably, the quality of weld formation is improved, the weld penetration is increased, the grain structure in weld zone is refined, the width of heat affected zone is narrowed, and the joint strength and toughness are enhanced, without showing apparent change of the relative element contents in the welded joint. In conclusion, coating of Cr2O3 active agent on the specimen surface is effective in improving the welding properties of laser welded stainless steel plates.

中文翻译：

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Cr2O3活性剂对光纤激光焊接不锈钢厚板焊接过程动力学行为及接头综合性能的影响

摘要 本研究采用新型“夹心”法结合高速摄像系统，实时监测不锈钢厚板活化激光焊接过程中金属蒸气、等离子体、小孔和熔池的动态行为。 . 同时，从接头焊缝形成、力学性能、显微组织、元素分布等方面对试件的焊接质量进行检测和分析。探讨了Cr2O3活性剂对焊接稳定性和试样质量的影响。结果表明，在试样表面充分涂覆活性剂可以减弱和抑制小孔内外金属蒸气和等离子体的产生和剧烈变化，增加小孔深度，改善小孔形状，减弱焊缝的振荡幅度。水池，并延长锁孔和熔池的更换周期。从而提高焊接过程的稳定性，较好地抑制气孔和飞溅缺陷的产生，提高焊缝成形质量，提高焊缝熔深，细化焊缝区晶粒组织，扩大热影响区宽度。变窄，提高了接头强度和韧性，而焊接接头中相对元素含量没有明显变化。综上所述，在试样表面涂覆Cr2O3活性剂可有效提高激光焊接不锈钢板的焊接性能。焊缝成形质量提高，焊缝熔深增加，焊缝区晶粒组织细化，热影响区宽度变窄，接头强度和韧性增强，相对元素含量无明显变化在焊接接头处。综上所述，在试样表面涂覆Cr2O3活性剂可有效提高激光焊接不锈钢板的焊接性能。焊缝成形质量提高，焊缝熔深增加，焊缝区晶粒组织细化，热影响区宽度变窄，接头强度和韧性增强，相对元素含量无明显变化在焊接接头处。综上所述，在试样表面涂覆Cr2O3活性剂可有效提高激光焊接不锈钢板的焊接性能。