Creep enhanced stainless steel containing 18 to 25% Cr is widely used as material for heat exchanger tubes in Ultra Super Critical boilers for thermal power generation, and the need to develop creep life evaluation techniques has increased. Mitsubishi Heavy Industries, Ltd. has developed a technique to evaluate the life of stainless steel heat exchanger tubes that accurately estimates the metal temperature of the tubes based on their microstructure, and this technique has already been applied to actual plants. In addition, to realize a life evaluation with higher accuracy, we have also been developing a new creep life evaluation method based on the amount of extremely small size creep void formation, which can directly evaluate damage without metal temperature estimation. This report describes the overview of these life evaluation techniques.
