Creep Crack Growth Behavior in Power Plant Boiler and Steam Pipe Steels

One of the important ingredients in remaining creep crack growth life assessment of elevated temperature power plant components is the material creep crack growth rate data. This report summarizes the currently available data on Cr-Mo and Cr-Mo-V steels most commonly used in steam pipes and boilers. All data are correlated with the crack-tip parameter, C_t. The accompanying creep deformation data and tensile properties are also included. The influence of in-service degradation, test temperature and the welding parameters such as impurity level and post-weld heat treatment (PWHT) on the creep crack growth behavior were examined. It was shown that the influence of nominal material chemistry, service degradation and test temperature can be normalized into a single da/dt versus C_t trend for the base materials. It was also shown that the level of impurities and the PWHT can significantly influence the da/dt versus C_t behavior in weldments.