Remaining life assessment of high-temperature components using threshold stress concept

The paper first presents global experience, including that of our laboratory, mainly with power plant components to show that it is possible to extend the life of some critical components 2-3 fold over the design life. Different approaches for remaining life assessment are also briefly discussed.
It appears that the main creep damage in so far as Cr-Mo and Cr-Mo-V steels are concerned, is an accumulation of creep strain. Hence, this paper suggests a new approach for creep life prediction based on threshold stress concept and stress-strain rate relationship. The approach is based on the analysis of creep and hot tensile data generated on a popular 1 Cr-0.3 Mo-0.25 V steel in the service exposed and the. virgin states and also on samples with a wide range of microstructures prepared from the virgin states. A summary of the main finding leading to development of a new approach has been given.