ひずみ範囲分割概念に基づくクリープ疲労損傷則と微小き裂進展挙動の関係(<特集>高温強度)

概要

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In order to clarify the validity of the previously proposed creep-fatigue damage rule, in which small crack growth curves are predicted by the crack growth rate equations based on the strain range partitioning concept and used as the damage accumulation curves, the correspondence between the predicted small crack growth behavior and the experimentally obtained behavior was examined. The small crack growth behavior of smooth bar specimens in PP, CP, PC and CC tests was observed for Mod.9Cr-1Mo steel at 600℃ by the surface replica technique, and compared with that predicted by the proposed damage rule. The tests were conducted under constant strain ranges, where 1.0% was chosen as the high strain range and 0.3%〜0.5% were chosen as the low strain ranges. The predicted small crack growth curves well corresponded with the experimentally obtained relationship between the maximum crack length and the life ratio except for the CP, PC and CC type low strain ranges. The deviation between the prediction and experiment for the CP, PC and CC type low strain range was found to be decreased by modifying the initial crack length in the proposed damage rule and by taking the crack initiation life into consideration like the case for the PP type low strain ranges.
1995-01-15