Creep properties of a reduced activation 9Cr3WVTaB martensitic steel after helium implantation

Influence of helium on creep rupture properties of a reduced activation 9Cr3WVTaB martensitic steel for fusion applications has been examined. Homogeneous helium implantation using α-particle irradiation at an accelerator was adopted to simulate transmutational production of helium in fusion reactors. Helium was introduced into creep specimens at 600 °C with concentrations up to 300 appmHe. Creep rupture tests at the same temperature were carried out on specimens both with and without helium. Both creep lifetime and rupture elongation were not so much affected by helium. All the implanted specimens failed in a perfectly intragranular ductile manner without any indication of grain boundary separation induced by helium. These results indicate good resistance of the steel against high-temperature helium embrittlement.