Product Code: JLA_14_3_136

Authors:
Kenichi Kamimuki
Takashi Inoue
Applied Laser Engineering Research Institute, 2085-16 Uenoyama, Fukasawamachi, Nagaoka, Niigata 940-2135, Japan

Kouzou Yasuda
Mikio Muro
Tokuhiro Nakabayashi
Technical Institute, Kawasaki Heavy Industries, 118 Futatsuzuka, Noda, Chiba 278-8585, Japan

Akira Matsunawa
Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan

In the Nd:yttrium–aluminum–garnet (YAG) laser welding of thick plates, reduction of porosity and monitoring the keyhole/molten metal behavior are very important issues to assure the high quality welding. The authors applied a side gas flow to prevent the porosity in the bead on plate welding with 6 kW Nd:YAG laser equipment. At the same time, a reflected Ar⁺ laser in the same axis as the Nd:YAG laser beam and the light emission from the weld were measured as monitoring signals. Under the optimum side gas condition, pores in the weld metal could significantly decrease, the penetration depth increased slightly, and the bead width became narrower. Under that condition, moreover, the generation of spatters was quite few. An acceptable limit of the transverse misalignment of the side gas nozzle position was about 1 mm. The misalignment could be detected by using the above mentioned monitoring signals. © 2002 Laser Institute of America.

Key words: laser welding, side gas, porosity, monitoring, keyhole