Significant developments have been made in recent years in the description of creep as a damage process. Advanced martensitic steels that expend over half their lives in the tertiary creep stage have been the focus of attention since their use temperatures are being extended to higher temperatures. Data available for assessing the predictability of the damage models are somewhat scarce since long-time exposure testing has generally been for constant temperature and load conditions. In this work, data are reviewed from relatively long-time tests that involved temperature and stress changes. The prediction of several damage models are compared to material behavior. Most of the comparisons are for 9Cr-1Mo-V steel in the temperature range of 538 to 649 C and for times in the range of 10,000 to 80,000 hours.

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