Relationship between plasma and keyhole behavior during CO2 laser welding

Naoki Seto; Seiji Katayama; Masami Mizutani; Akira Matsunawa

doi:10.1117/12.377029

7 February 2000 Relationship between plasma and keyhole behavior during CO₂ laser welding

Naoki Seto, Seiji Katayama, Masami Mizutani, Akira Matsunawa

Proceedings Volume 3888, High-Power Lasers in Manufacturing; (2000) https://doi.org/10.1117/12.377029
Event: Advanced High-Power Lasers and Applications, 1999, Osaka, Japan

Abstract

It is well known that porosity is easily formed in high power laser welding, which is quite a serious problem to be solved. At present, there are few reports studying interrelationship between keyhole and plasma behavior with the objective of understanding the effect of shielding gas on porosity formation. In this study, therefore, the relationship between keyhole and plasma behavior was observed directly by using two synchronized ultra high-speed cameras and X-ray transmission observation system. In the case of He gas, metallic plasma was continuously formed, and the keyhole was always open. It was observed that many large bubbles, which were formed from the tip of a keyhole, were trapped at the solidifying front in the rear part of the molten pool, and lead to the porosity formation. On the other hand, in the case of N₂ gas, big nitrogen plasma was formed above the weld bead periodically, and its absorption of laser caused the disappearance of metallic plasma and keyhole. This periodical interval and duty were different among materials used and affected the bubble and porosity suppression beneficially.

Citation Download Citation

Naoki Seto, Seiji Katayama, Masami Mizutani, and Akira Matsunawa "Relationship between plasma and keyhole behavior during CO₂ laser welding", Proc. SPIE 3888, High-Power Lasers in Manufacturing, (7 February 2000); https://doi.org/10.1117/12.377029

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