Long-term creep behavior of 9–12%Cr power plant steels

Creep behavior and degradation of creep properties of high-temperature materials are phenomena of major practical relevance, often limiting the lives of components and structures designed to operate for long periods under stress at elevated temperatures. Because life expectancy is, in reality, based on the ability of the material to retain its high-temperature creep strength for a period of at least twice the projected design life, methods of creep property assessment based on physical changes in the material that are likely to occur during service exposure rather than simple parametric extrapolation of the short-term data are necessary. This work attempts to highlight the problem areas just in this respect. Physical models in the prediction of microstructure–creep property relationship in creep-resistant steels are reviewed. The proposed approaches are illustrated by recent experimental results on modified high creep strength 9–12%Cr martensitic steels.