Product Code: JLA_14_2_68

Authors:
Yoshiaki Shimokusu
Kobe Shipyard & Machinery Works, Mitsubishi Heavy Industries Ltd., 1-1-1 Wadasaki-cho, Hyogo-ku, Kobe Hyogo 652-8585, Japan

Seiji Fukumoto
Kobe Shipyard & Machinery Works, Mitsubishi Heavy Industries Ltd., 1-1-1 Wadasaki-cho, Hyogo-ku, Kobe Hyogo 652-8585, Japan

Michisuke Nayama
Technology Planning Department, Technical Headquarters, Mitsubishi Heavy Industries Ltd., 3-3-1 Minatomirai, Nishi-ku, Yokohama Kanagawa 220-8401, Japan

Takashi Ishide
Takasago R&D Center, Mitsubishi Heavy Industries Ltd., 2-2-1 Shinhama, Arai-cho, Takasago Hyogo 676-8686, Japan

Shuho Tsubota
Takasago R&D Center, Mitsubishi Heavy Industries Ltd., 2-2-1 Shinhama, Arai-cho, Takasago Hyogo 676-8686, Japan

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

Seiji Katayama
Joining and Weld Research Institute of Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan

Laser beam welding is used for precise parts such as core internal parts in nuclear power plants that require high quality. To weld large-scale and thick-wall products, the high power laser beam must be transferred and a deep penetration welding procedure must be developed. In this article, therefore, an optical fiber transmission system for 7 kW class high power yttrium–aluminum–garnet (YAG) laser and pulse modulated laser welding techniques were developed to obtain deep penetration. The detailed observation of the weld pool and keyhole dynamics using a high-speed camera and x-ray transmission system was carried out to understand high power YAG laser welding phenomena. It has been clarified that there are proper pulse duty and pulse duration for optimum welding condition to obtain sound and efficient weld. After confirmation of the high power YAG laser welding joint performance, this procedure has been applied to the welding of stainless steel tanks for the nuclear fuel reprocessing plant. © 2002 Laser Institute of America.