Creep-fatigue damage and life prediction of alloy steels

Establishment of a creep-fatigue life prediction method is important for assessment of the remaining life of high temperature components. Creep-fatigue tests with strain hold duration including 100 hours per cycle have been carried out on high-temperature component materials in CRIEPI. The relationship between creep-fatigue life property and damage evolution during strain hold is discussed. It is suggested that creep damage during stress relaxation should be divided into the matrix creep damage and the grain boundary creep damage from the comparison between the experimental results and the creep deformation mechanism map. A nonlinear damage accumulation model (NLDA) is proposed based on experimental results and theoretical considerations. Creep-fatigue lives of high-temperature materials are predicted with high accuracy using the NLDA model.