FRACTAL RESEARCH ON CRACKS PROPAGATION OF GAS PIPELINE X52 STEEL WELDING LINE UNDER HYDROGEN ENVIRONMENT

Based on the theory of hydrogen enhanced localized plasticity of the hydrogen induced cracking and considered the effect of residual stress produced by eliminated stress heat treatment, a fractal model of hydrogen induced cinching was presented, and a relationship among the effective surface energy (H), fractal dimension D and stress intensity factor of hydrogen induced cracking, KIH, for welding pipeline under hydrogen environment was set up, from which the relationship of D and KISCC is obtained. The model was verified experimentally to be correct.