LAZAROVA Tsvetelina

Spoluautoři YORDANOVA Rozina, ANGELOVA Donka

Fatigue in stainless steel-candidates for hydrogen storage and infrastructure is described mathematically at different loading conditions. The investigated steels are: SUS304, SUS316 SUS316L and SUS405. All the tests are carried out under tension-compression fatigue at different loads and a stress ratio R= −1. Specimens are machined in hour-glass shape with artificial hole from which initial cracks start their propagation. For finding the effect of hydrogen on fatigue behaviour of investigated steels, the specimens are divided into two groups: of hydrogen charged and uncharged ones. The obtained fatigue data of each steel are presented in plots “Crack length - Number of cycles” and “Fatigue crack growth rate – Crack length”. A mathematical model is found for the data in the presentation “Fatigue crack growth rate – Crack length”. The model consists of double-parabolic-linear-curve for all steels, which makes it possible to prognosticate their fatigue behaviour under different loading conditions. The adequacy of the presented model is checked and proved by comparison between experimental fatigue lifetimes and those calculated by the model.