SPECIFIC FEATURES OF THE DEFORMATION AND FRACTURE OF LOW-ALLOY STEELS IN HYDROGEN-CONTAINING MEDIA: INFLUENCE OF HYDROGEN CONCENTRATION IN THE METAL

摘要

We establish basic regularities of the influence of hydrogen concentration in metals on the fracture strength of low-alloy pipe steels. In particular, we determine the characteristic value of hydrogen concentration for which the mechanism of its influence on the deformation of specimens by uniaxial quasistatic tension changes, namely, below this concentration, hydrogen enhances the plasticity of the material and, above this concentration, promotes its embrittlement. For the first time, we detected an ambiguous relationship between fatigue crack-growth rate and the volume hydrogen concentration in these steels under cyclic loading in hydrogen-containing media and established its value for which the cyclic crack growth resistance of steel increases. We revealed a correlation between the intensity of hydrogenation of steels and the strength of passive film at the crack tip, which gives us an instrument for the development of efficient barriers against hydrogen penetration into the materials.