Numerical investigation on melting characteristics of minuteness metal powders by laser welding

Takase, Kazuyuki; Shobu, Takahisa  ; Tsukimori, Kazuyuki; Muramatsu, Toshiharu

At the commercial use stage in sodium-cooled fast breeder reactors, securing maintenance and repair better than an equal to that of present water-cooled reactors is needed. Especially a repair technology that secures the plant integrity for long-term operation period becomes indispensable in the heat exchanger tubes of the steam generator that form the boundary of sodium and water coolants. Then the present study focused on the standardization of welding technology with a laser. An experimental study regarding the welding of a stainless steel plate with the laser using fine metal powders is being performed. Moreover, a numerical study is performed to simulate the welding of the fine metal powder on the stainless steel plate. The fine metal powder is made of iron, and is heated by the laser beam, and then melts exceeding the melting temperature. This paper reports the computational results of the welding phenomenon of some metal powders which changes from solid to liquid and liquid to solid. The results were compared with the experimental results qualitatively. It was concluded that a welding simulation is possible and the present numerical approach will be effective.