Abstract
Fatigue tests on SCM435 steel quenched at 860℃ and tempered at 580℃ were carried out with specimens containing a small artificial hole under R=0.4 and frequency =0.2〜2 Hz. The fatigue life of hydrogen charged specimens decreased in comparison with uncharged specimens. The acceleration of fatigue crack growth rate was observed at ΔK < 30MPaJm in hydrogen-charged specimens. However, there exists the upper bound of the acceleration of fatigue crack growth rate in hydrogen-charged specimens. Two types of peculiar fracture appearances were observed in the hydrogen-charged specimen. One is facets in the lower ΔK region. Another is radial pattern fracture surfaces in the higher ΔK region.
