Reduced activation ferritic steel (JLF-1) is one of the leading candidates for blanket/first-wall structures of the D-T fusion reactor. In fusion application, the experimental data for fracture toughness, fatigue life and fatigue crack growth behavior are very important to estimate a safety life in terms the critical crack length of a blanket with the irradiation. Since welding must be performed when the support structures are constructed, the fracture behavior of the weld joint has to be characterized as well as the base metal. The objective of this study is to investigate fatigue crack growth and fracture toughness behavior in the JLF –1 steel and its TIG welded joint. The fatigue crack growth test was carried out by constant amplitude cyclic load testing under a stress ratio of 0.3 at RT and 400ºC using full size compact tension (FCT) and half size compact tension (HCT) specimens of base metal and TIG weldments. And the effects of specimen configuration and TIG welding on fracture toughness test were investigated.


Nuclear fusion energy reactors not only need high efficiency of energy production but also development of structural materials that allow efficient operation. The candidate blanket structural materials for nuclear fusion reactors may be RAFs, vanadium alloys and SiC/SiC composite etc. in accordance with cooling system chosen (Shiba, Suzuki, Hishinuma, 1996). RAFs is particularly suited for nuclear fusion reactors because of a low coefficient of thermal expansion and excellent heat conductivity. Recently, development and testing has been carried out for F82H and JLF-1 steels developed by the JAERI and JUPITER programs, respectively (Jitsukawa, Tamura, Schaaf, Klueh, Alamo, Petersen, Schirra, Spaetig, Odette, Tavssoli, Shiba, Kohyama, Kimura, 2002). The International Fusion Materials Irradiation Facility (IFMIF) is required to evaluate the material performance under a fusion relevant environment.

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