Abstract: A new method for strain-based fatigue reliability analysis is constructed by considering interference between the random fatigue strain applied and capacity histories. Recently found scatter of the cyclic stress-strain (CSS) responses of a nuclear engineering material，1Cr18Ni9Ti stainless steel pipe-weld metal，is taken into account. Different from the existent methods that took the material constants in the Coffin-Manson cyclic strain-life (CSL) relation as independent random variables，present work treats the material constants in the Ramberg-Osgood CSS and Coffin-Manson CSL relations as dependent random variables from the fits of test data. These relations are approximated by the probability-based CSS and CSL curves，respectively. Probability density functions of the random fatigue strain applied and capacity histories are analytically obtained from the probability-based curves. This method can be applied in practice by a form of reliability-stress-life curves and extrapolated conveniently to the case of deterministic CSS relation as the existent methods did. Availability of this method is indicated by an analysis of the material test results.

Key words: Fatigue, Pipe, Random cyclic stress-strain, Reliability, responses, Stainless steel, Strain analysis, Weld metal