Research Of The Irradiation Resistance Performance On The SCRAM Steels

Fusion energy as an efficient, clean, safe and limitless energy is one of the importantleading energy in the future mankind society. In order to break away from the energy crisisas soon as possible, countries in the world have been working together to establish anInternational Thermonuclear Experimental Reactor. The research and analysis of suitablestructural materials under the harsh conditions and the selection of the final material arecrucial steps in the construction process of nuclear fusion reactors. In order to furtheroptimize the structure and anti-radiation properties of structural materials and improve thelifetime, we designed a Cr-W-V-Ti-N new super clean reduced activation martensiticsteels(namely SCRAM Steel), conducted a multifaceted evaluation of its radiationresistance performance and optimized its composition and performance.Irradiation hardening and irradiation embrittlement induced by the Fe+He+H ionsirradiation at300℃were both found in the SCRAM-1(0.0064Ti-0.095V-77N) steel andSCRAM-3(0.018Ti-0.092V-110N) steel. The irradiation-induced tensile strength changeratio for SCRAM-1steel was13.4%, compared to7.2%for SCRAM-3steel. Theirradiation-induced impact strength change ratio for SCRAM-1steel was30.8%,compared to2.68%for SCRAM-3steel. Comparing the irradiation-induced change ratio,we found that the radiation resistance stability of SCRAM-3is better thanSCRAM-1.Whether to irradiation hardening or to irradiation embrittlement, SCRAM-3steels have a more stable structure.After single beam(Fe) and double beam(Fe+H or Fe+He) ion irradiation, thetoughness of SCRAM-6(0.005Ti-0.25V-170N) steel and SCRAM-9(0.015Ti-0.25V-700N)steel declined for a certain extent due to the irradiation embrittlement effects, the impactstrengths of both steels have undergone varying degrees of decline. Addition of He or H ion irradiation on the basis of Fe ion irradiation, the impact strength of the two steelsfurther declined for the synergistic effect. However the strength changes of SCRAM-9steel were relatively smaller.After3MeV Fe ion irradiation with radiation dose of20dpa, the impact strength ofSCRAM-4(0.011Ti-0.094V-150N) and SCRAM-9(0.015Ti-0.25V-700N) steels increasedfor a certain extent. But the impact strength of SCRAM-5(0.021Ti-0.097V-150N) steeldecreased slightly. The irradiation-induced impact strength change ratio for the SCRAM-4steel was28.9%, compared to17.9%for SCRAM-9and-4.1%for SCRAM-5steels. Asthe increasing content of Ti in SCRAM steels, the change of the impact strength of steelsgot smaller and the stability of their structures gradually got better.Comparing the strength change ratio of the SCRAM steels after He ions irradiation,we found that In the SCRAM steels with the same content of N and V, SCRAM steels withhigher content of Ti had smaller irradiation-induced impact strength change ratio. It’s tosay that SCRAM steels with higher content of Ti had more stable structures and betterirradiation resistance. In the SCRAM steels with the same content of V and no content ofTi, the level of the N content made no obvious influence on the irradiation-induced impactstrength change ratios, which were all about-22~24%. However the increase of contentof Ti, irradiation-induced impact strength change ratio got smaller. The irradiation-inducedimpact strength change ratio of high-Ti SCRAM-9steel was only17.4%. In the SCRAMsteels with the same content of Ti and N, in Ti, N content close when V content is higher,the smaller the rate of change of SCRAM irradiated steel, SCRAM steels with highercontent of V had smaller irradiation-induced impact strength change ratio. It’s to say thatSCRAM steels with higher content of V had more stable structures and better irradiationresistance. Taken together, we found SCRAM-3(0.018Ti-0.092V-110N) and SCRAM-9(0.015Ti-0.25V-700N) steels had more stable structures and better irradiation resistance.