Effect of specimen size on fatigue properties of reduced activation ferritic/martensitic steels

Small specimen testing technology (SSTT) and related remote-control testing techniques are indispensable for the effective use of the limited volumes of materials test reactor and proposed intense neutron sources. As a part of this work, a new fatigue test machine with a laser extensometer for hot-cell usage has been developed. Materials used in this work were Japanese reduced activation ferritic/martensitic steel (RAFs), JLF-1 (Fe-9Cr-2W-V-Ta) and its weldment (WM). Correlations between fatigue life characteristics and fracture mechanisms were investigated for full- and mini-sized hourglass type specimens to clarify the effect of specimen size on fatigue properties. These tests revealed that there was not a significant difference in the number of cycles to failure in both specimens, except for the case of very low cycle fatigue.