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内容記述 |
A reduced activation ferritic martensitic (RAFM) steel known as F82H is the primary candidate for structural materials in the water-cooled ceramic breeder test blanket module (WCCB TBM) for ITER. Given that the WCCB TBM experiences cyclic loads from cooling water pressure, heat load, and electromagnetic forces within the temperature range where F82H is susceptible to creep, a quantitative investigation of the creep-fatigue (CF) lifetime for this material is essential. For a new material like F82H, developing a CF lifetime curve requires substantial time and extensive data. This study aims to evaluate and predict the CF lifetime of F82H by combining limited CF experimental results with a strain-range partitioning method. Additionally, a novel approach is proposed based on these findings and similar steel grades, such as 9Cr-1Mo-V, to predict the CF lifetime of F82H. The experimental work involves a round-bar CF specimen with a gauge section measuring φ5 mm x 12 mm, as specified in ASTM E2714-13. Tension-comparison tests are conducted at 550°C in air, featuring a stress ratio of R = -1 and a strain rate of 10^-1 %/s. The total strain ranges from 0.75% to 1%, with a holding duration of 180 seconds per cycle at the peak compressive stress. Using the experimental data and the strain-range partitioning method, constitutive relations for evaluating the CF lifetime of F82H are formulated. The predicted lifetime aligns with experimental results by a factor of two. The specifics of the CF lifetime evaluation and prediction for F82H will be presented in detail. |
