Fatigue tests at room temperature in vacuum, air and hydrogen have bee
n carried out on specimens of DIN 1.4914 martensitic stainless steel i
n load-controlled, push-pull type experiments. Fatigue lifetimes in hy
drogen are significantly lower than in both vacuum and air and the deg
radation is enhanced by lowering the test frequency or introducing hol
d times into the tension half-cycle. Fractographic examinations reveal
hydrogen embrittlement effects in the form of internal cracking betwe
en fatigue striations together with surface modifications, particularl
y at low stress amplitudes. It is suggested that gaseous hydrogen can
influence both fatigue crack initiation and propagation events in mart
ensitic steels.