2.25Cr-1Mo鋼溶接継手のクリープ, クリープ疲労強度に及ぼす試験片寸法効果

概要

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In this study, influence of specimen geometry on creep and creep-fatigue strength was discussed based on experimental and FE analysis results of weld joints. Increase of creep strain under the creep condition in the fine grain region is faster than that in other portion both in the standard and large size weld joint specimens. Increase of creep strain of fine grain region in the large specimen is faster than that in the standard specimen resulting in the difference of creep rupture time. It was found that difference of stress multiaxiality, which is larger in the large specimen, caused the difference of creep strength. On the other hand, failure life of the large weld joint specimen is shorter than that of the standard specimen in the creep-fatigue loading. The main crack propagated through fine grain region in the standard specimen and it propagated through coarse grain region in the large specimen. These difference can be interpreted by the difference of plastic and creep strains under creep-fatigue condition between two specimens. Failure location and life of the weld joint specimens could be well predicted by the nolinear damage accumulation model based on FE analysis results.
2000-09-25