Product Code: ICAL09_1605

Welding of Thick Stainless Steels Plates Up to 50MM with High Brightness Lasers
Authors:
Xudong Zhang, Hitachi Ltd.; Hitachi-shi, Ibaraki-ken Japan
Eiji Ashida, Hitachi, Ltd.; Hitachi-Shi, Ibaraki-Ken Japan
Shoh Tarasawa, Hitachi-Ge Nuclear Energy, Ltd.; Hitachi-Shi, Ibaraki-Ken Japan
Yusuke Anma, Hitachi-Ge Nuclear Energy, Ltd.; Hitachi-Shi, Ibaraki-Ken Japan
Masaya Okada, Hitachi-Ge Nuclear Energy, Ltd.; Hitachi-Shi, Ibaraki-Ken Japan
Seiji Katayama, Osaka University; Osaka Japan
Masami Mizutani, Osaka University; Osaka Japan
Presented at ICALEO 2009

Thick-section stainless steels are widely used in components and structures for nuclear power plant. Laser welding is being considered as a high-efficiency method to instead of arc welding for some components, in order to improve production efficiency and reduce residual stresses of the heat-affected zone. In this paper, multi-passes narrow gap welding of 50mm thick SUS316L plates with 6 kW disk laser was firstly investigated. The effect of welding conditions on weld bead geometry and welding defects was studied. It shows that lack-of-fusion could be prevented by optimizing the relationship between laser power intensity and the deposited metal volume. Butt joint of 50mm thick plates with narrow gap could be performed with 8-passes welding at laser power of 6 kW and welding speed of 0.4 m/min. In order to reduce weld passes further, gas jet assistant laser welding was tried to welding thick SUS316L plates with a 10 kW fiber laser. The result shows that butt-joint welding of 40 mm plated without filler wire could be performed at 0.3 m/min welding speed without porosity and other welding defects. As for 50 mm thick plates, good weld bead could be obtained with bead-on-plate welding from both sides at 0.2 m/min welding speed.