DIRECTIONALITY OF HYDROGEN ABSORPTION IN HIGH TENSILE STRENGTH STEEL.

A study on the effect of cathodic hydrogen charging on the directionality of hydrogen blistering, macro stress and micro-strain in the high tensile strength steel specimens sampled from different directions was carried out by X-ray diffraction technique and hydrogen permeation measurement. Hydrogen blisters and hydrogen cracks formed in the steel plate by cathodic charging occur parallel with the rolled surface of the plate but not in other directions. Lattice parameter of the rolled surface of the plate increases with charging and that of the thickness surface increases at the onset of charging and then decreases with charging. The steel membrane sampled with the rolled surface of the plate has a lower diffusivity and a higher solubility of hydrogen than the samples in other directions.