|Spoluautoři LAZAROVA Tsvetelina, ANGELOVA Donka, GEORGIEV Alexander|
Fatigue in Cr–Mo steel, JIS SCM435, candidate for use in fuel cell vehicles is investigated at different test frequencies in two groups of hydrogen charged and uncharged specimens under tension-compression fatigue and stress ratio R= −1. Specimens are machined in hour-glass shape with artificial hole from which initial cracks start their propagation. The obtained fatigue data of each frequency are presented in plots “Crack length, a - Number of cycles, N” and “Fatigue crack growth rate, da/dN – Crack length, a”. A mathematical model consists of double-parabolic-linear-curve is found for the data in the presentation “Fatigue crack growth rate, da/dN – Crack length, a” and a comparison made between those curves for the different frequencies. The adequacy of modelling is checked and proved by comparison between experimental fatigue lifetimes and the calculated by the model.