Assessment of creep life fraction for in-service high-temperature components

The grain boundary etching method for the assessment of material degradation has received much attention because it is simple, inexpensive and easy to apply to in-service high-temperature components. The effectiveness of the method is verified by successfully applying it to in-service components of aged fossil power plants such as superheater and reheater headers. A degradation parameter is employed using intersecting point ratio. The material degradation for in-service high-temperature components is estimated by a Larson-Miller parameter which is calculated from aging temperature and aging time. Creep tests are performed to characterize the correlation between intersecting point ratio and life fraction of service material. The possibility is confirmed to apply the grain boundary etching method to the creep life assessment of in-service high-temperature components.