Multiplicative model for out-of-phase thermal fatigue degradation of ferritic-martensitic steel MANET-II

Hollow specimens of a Cr-steel have been subjected to triangle temperature cycles and different temperatures. Out-of-phase thermal fatigue lifetime is analysed and compared to isothermal fatigue data close to the mean cycle temperature. Segments associated with different temperature ranges and isothermal fatigue lines display in logarithmic scale only a slight slope difference. The thermomechanical fatigue degradation model suggests that the strain-related degradation per cycle is multiplied by a factor reflecting the particular effect of temperature oscillation. (orig.)