Optical observations of fatigue crack growth behaviour of a low-alloy pressure vessel steel in high-temperature pressurized water: Katada, Y., Nagata, N. and Sato, S. Int. J. pressure Vessels Piping Oct. 1991 48 (1) 37–52

Abstract

This paper reviews the capabilities of a plasticity-induced crack-closure model to predict fatigue lives of metallic materials using `small-crack theory' for various materials and loading conditions. Crack-tip constraint factors, to account for three-dimensional state-of-stress effects, were selected to correlate large-crack growth rate data as a function of the effective-stress-intensity factor range (ΔKeff) under constant-amplitude loading. Some modifications to the ΔKeff rate relations were needed in the near-threshold regime to fit measured small-crack growth rate behavior and fatigue endurance limits. The model was then used to calculate small- and large-crack growth rates, and to predict total fatigue lives, for notched and un-notched specimens made of two aluminum alloys and a steel under constant-amplitude and spectrum loading. Fatigue lives were calculated using the crack-growth relations and microstructural features like those that initiated cracks for the aluminum alloys and steel for edge-notched specimens. An equivalent-initial-flaw-size concept was used to calculate fatigue lives in other cases. Results from the tests and analyses agreed well.