The effect of V8C7 size on hydrogen diffusion behavior and hydrogen induced cracking in pipeline steel

This study revealed the relationship between V8C7 size and hydrogen diffusion behavior as well as hydrogen induced cracking (HIC) in pipeline steel. Hydrogen permeation and HIC susceptibility tests were implemented on five conditions with different V8C7 sizes but identical volume fractions. The results proved that with increasing of V8C7 size, the hydrogen effective diffusivity was first decreased and then increased. Increasing the proportion of small size (coherent and semi-coherent) V8C7 increased the effective hydrogen trapping densities, decreased hydrogen diffusion coefficient, improved the distribution of diffusible hydrogen atoms and then the HIC susceptibility of steels was decreased. (c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.