Mechanical properties of F82H/316L and 316L/316L welds upon the target back-plate of IFMIF

Furuya, Kazuyuki*; Ida, Mizuho; Miyashita, Makoto; Nakamura, Hiroo

The current material design of the IFMIF back wall in Japan consists of a stainless steel type-316L and F82H steel. The 316L and F82H are welded each other. The 316L region of the back wall is also welded with the target assembly made of 316L. Since the back-wall is operating under severe neutron irradiation condition (50 dpa/year), it is therefore important to perform metallurgical and mechanical tests for these welds. In result of the tests, significant issues were not found in the F82H/316L TIG-weld. On the other hand, although the 316L/316L YAG-weld offered the weld without any harmful weld defect, the hardness decreased somewhat in the fusion metal. The rupture occurred in the fusion metal, and the strength and elongation decreased somewhat. Furthermore, small dimples include several number of large voids were also seen in the fracture surface.