Effect of post-weld heat treatment on hydrogen-assisted cracking behavior of high-strength process pipe steel in a sour environment

The influence of post-weld heat treatment on hydrogen-assisted cracking of process pipe steel is investigated in terms of change in hydrogen trapping site. This study reports that, contrary to other microstructures, in acicular ferrite, cementite bodies acting as reversible trapping sites for hydrogen atoms are newly precipitated along the grain boundary by the post-weld heat treatment conducted at 620 °C. This leads to an increase in diffusible hydrogen content in the steel that makes it more susceptible to hydrogen-induced cracking.