X-Ray Study on the Hydrogen Charged Steels

Abstract

In order to account for the embrittled phenomenon in steels charged with hydrogen, several considerations have so far been proposed, such for instance as the rift network theory, the void theory, the formation of cottrell atmosphere, and the interaction of hydrogen in the lattice work and in the stress field. The authors have tried to make an X-ray study of the mechanism of steel getting charged with hydrogen by performing comparative experiments on the polycrystalline material and on the single crystal material, both electrolytically charged with hydrogen. The former has been subjected to analysis of the X-ray diffraction line profiles, and the latter to analysis of its lattice distortion. The results indicate that thus introduced hydrogen gives rise to plastic deformation in the crystal lattice and there is no recovery phenomenon observable after having been subjected to room temperature aging. By annealing treatment of the material at higher temperature, however, the crystal have been recovered in a similar fashion to mechanically deformed crystal.It is believed that the recovery in this case is not due to the diffusion process of hydrogen. In the case of single crystal, the micro-focus X-ray source (30∼20 micron) is employed to take Laue pictures which showed the heavily deformed spots on the films. This is believed to be due to the distortion in the crystal lattice as well as to the existence of void caused by being charged with hydrogen.