Characteristic investigation of stress-hydrogen coupling hydrogen diffusion of X80 steel based on finite element simulation

Since hydrogen atoms are enriched in the corrosion defect regions of steel pipelines under stress-induced effects when transporting gaseous hydrogen, this leads to the hydrogen embrittlement (HE) phenomenon. Therefore, this paper conducts hydrogen diffusion simulation experiments on X80 pipeline steel for defective pipelines under different stress fields to observe the combined effects of internal defects, stress fields, and hydrogen. By coupling the stress field and hydrogen concentration field under different internal pressures sequentially, observing the hydrogen diffusion distribution of the pipeline under the effect of corrosion defects and stress field, calculating the hydrogen concentration of the X80 pipeline steel samples under different working conditions, and analyzing the impact of hydrogen damage of the corroded pipeline under the impact of stress-hydrogen coupling. The results show that at 24h, the Von Mises stress at 10MPa internal pressure at the defect increased by 37% compared with 5MPa, and the hydrogen concentration in the 10MPa stress field increased by 43% compared with 5MPa. Therefore, with the increase of internal pressure, the stress field of corroded pipeline increases. Hydrogen diffusion under stress induction causes hydrogen atoms to gather in the stress concentration area, thus endangering the safety of the pipeline.