Improving HIC resistance of pipe-steel by Ti/Mg treatment with insights into hydrogen migration

The presence of inclusions in steels is responsible for hydrogen-induced cracking (HIC), which necessitates control over their size and distribution. The aims of this study are to investigate the effects of different inclusion-modifying elements on steels, as well as reveal the impact of inclusions on hydrogen migration. Various methods, including HIC evaluation, electrochemical hydrogen permeation, silver microprint, and in-situ hydrogen escape observation, are utilized. The results indicate that steel with a Ti/Mg content ratio of 4:1 exhibits favorable comprehensive resistance against HIC. Moreover, the observation of in-situ hydrogen escape observations reveals that steels with a higher number of hydrogen bubbles and a higher ratio of bubbles related to the inclusions demonstrate better HIC resistance. The refined, dispersed, and multi-compounded inclusions facilitate the formation of more complex trapping sites, ultimately improving the dispersion and pinning of dissociative hydrogen atoms. Consequently, employing a multicomponent inclusion modification strategy holds promise for the development of hydrogen-resistant pipeline steel.