Abstract
High-temperature components in advanced power systems suffer multi-axial stress states due to structural discontinuity, thermal gradient and other factors, and creep life evaluation is essential for the long-term safe operation of the system. Existing codes and standards provide different creep life evaluation methods combined with single-node failure criterion, but this remarkably underestimates the actual failure life of the component. Based on this, a whole-section failure criterion for creep life evaluation of components at elevated temperatures is proposed. Creep tests of notched components with various acuity ratios are conducted. Margin differences between single-node and whole-section failure criteria are evaluated, using creep life evaluation methods in ASME and RCC-MRx codes. Results indicate that compared with single-node failure criterion, the whole-section failure criterion could remarkably reduce conservatism degree. Creep life evaluation method in ASME code is less conservative than that in RCC-MRx code for notched cases included, irrespective of the safety factor effect. The conservatism degree of creep life evaluation methods is related to specimen type and acuity ratio of notched components.
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