Abstract
In order to contribute to the development of first wall/blanket structural materials in nuclear fusion reactors, we have assessed the influence of nuclear-transmutational helium, which is widely known to often induce grain boundary embrittlement at high temperatures, on fatigue properties of a candidate reduced-activation martensitic steel, IEA (International Energy Agency) version of F82H (Fe-8%Cr-2%W-0.2%V-0.04%Ta). Utilizing α-particles from an accelerator, helium was introduced into specimens at 823 K to a concentration of about 100 appmHe. Through the subsequent fatigue tests at the same temperature, it has been demonstrated that both fatigue life and gauge extension to failure were not significantly deteriorated by helium. The appearance of fracture surfaces remained perfectly ductile and transgranular after helium implantation and no indication of grain boundary decohesion was detected. These results would reflect prominent resistance to the helium-embrittlement in this kind of steel and suggests their potential for future fusion applications.
