Stress/strain distributions in fiber laser welded materials using a minute metal powder

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

As sodium-cooled fast breeder reactors have reached a commercial use stage, a securing maintenance and repair superior to that of present water-cooled reactors is requested. We are aiming at the standardization of fiber laser welding technology using minuteness metal powder that allows three-dimensional micro-process. In the present study, the internal distribution of residual stresses/strains induced in welded materials by the present technology is evaluated methodologically. The specimens welded under various laser conditions were made from S50C. We show that the surface distribution of residual stresses of almost all specimens were tensile stress in weld and non-stress in body irrespective of the laser scanning direction or the laser scanning speed. On the other hand, we find that the internal distribution of residual strains of specimens were tensile stress beneath the welding and compression strain under the tensile strain area.