Comparison of fracture toughness of 9Cr-1W-0.3Ti ODS steel clad material evaluated using three different η and γ factors

9Cr-1 W-0.3Ti ferritic martensitic (FM) Oxide Dispersed Strengthened (ODS) steel is a candidate clad material for France’s future sodium-cooled fast breeder reactor. Fracture toughness of the FM ODS steel evaluated using pin-loaded tension (PLT) is already reported, which was evaluated using η pl and γ pl factors estimated by the domain integral (DI) method. The fracture toughness was re-evaluated again using η pl and γ pl factors estimated by the load separation (LS) method, and using η pl and γ pl factors reported in the literature estimated by the limit load (LL) method, and it was compared with the value already reported. The accuracy of the η pl and γ pl factors estimated by the LS method, relative to the DI and LL methods, is discussed in terms of their similarity to the compact tension specimen and the insensitivity of J IC obtained using LS-derived factors to a/W . Although the η pl and γ pl factors from the DI, LS, and LL methods differed, all three yielded nearly identical J IC values, indicating that any method can be used for single-value fracture toughness, while LS method derived factors are recommended when a complete J-R curve is required for safety analysis.