Abstract
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.
The following results were obtained.
(1) Hydrogen blisters and hydrogen cracks formed in the steel plate by cathodic charging occur parallel to the rolled surface of the plate but not in other directions. (2) Lattice parameter of the rolled surface of the plate increases with charging and that of the thickness surface increase at the onset of charging and then decreases with charging. (3) Compressive macro stress is produced in the rolled surface of the steel plate with charging but small tensile macro stress occur in the thickness surface of the steel plate. Micro-strain in the rolled surface of the plate increases with charging, while that in the thickness surface of the plate shows no remarkable change. (4) The directionality of diffusivity and solubility of hydrogen in the steel plate is also observed. The steel membrane sampled parallel to the rolled surface of the plate has a lower diffusivity and a higher solubility of hydrogen than the samples of other directions.
