| Reduced activation ferritic/martensitic steels?RAFM? are important candidate materials for future fusion nuclear reactors because of their high thermal conductivity, low thermal expansion rate and high resistance to irradiation swelling performance. The influence of high concentration helium produced by nuclear reaction?n,??on the micro-structure and macro-properties is an important issue limiting the service lifetime of the materials. In the present work, helium implantation to three different doses(100, 1000, 10000 appm helium, corresponding to 6x10-3, 6x10-2, 6x10-1dpa) was carried out to investigate irradiation hardening of two RAFM Steels.Multi-energy He ion-beams at 320 k V high-voltage platform were used to get a damage plateau from surface to 1?m depth in specimens. And Sn-irradiated sample were added to investigate the effect of He concentration on irradiation hardening. The continuous-stiffness test by a Nano-indentor G2000 was carried out. Data of nano-hardness were analyzed based on Nix-Gao model. And data of nano-hardness of the He-implantation region were obtained. It is shown that there is an 1/2-power law relationship between the hardening and the irradiation damage level. Before helium implantation, the hardness of the CLF steel is slightly lower than that of the CNS steel.However, with the increase of helium-implantation dose, the hardening is more obvious in CLF steel. Further investigation of microstructures is needed to get a deeper understanding of the hardening mechanism. He embrittlement is the main reason for the irradiation embrittlement of stainless steel materials. |
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