About the Nature of Quasi-Cleavage in Low-Carbon Steel Embrittled with Hydrogen

Scanning electron microscopy and confocal laser scanning microscopy are used to study a fracture surface of hydrogen-charged low-carbon steel, which has been deformed in air at room temperature to 12% residual strain and then crushed in liquid nitrogen. It is shown that the quasi-cleavage facets formed during the room-temperature deformation have a strongly curved surface in contrast to the flat cleavage facets formed under the loading in liquid nitrogen. It is inferred that the quasi-cleavage facets in the hydrogen-charged steel do not form by the mechanism of cleavage in the deformed structure.