Effect of stress and strain on hydrogen permeation process in X80 pipeline steel

Hydrogen permeation kinetics in X80 pipeline steel under different tensile stress-strain conditions were studied using Devanathan-Stachurski experiments and first-principles calculations. Results show that increased tensile stress slightly raises the diffusion coefficient and significantly boosts subsurface hydrogen concentration in elastic deformation. Shallow hydrogen traps formed under micro-plastic deformation impede hydrogen permeation. Operando synchrotron X-ray diffraction confirmed these traps as dislocations and revealed dislocation multiplication before yielding. the relationship between tensile stress and subsurface hydrogen concentration, as well as plastic deformation and hydrogen trap density were established and combined with finite element simulations to demonstrate hydrogen permeation kinetics during elastic-plastic deformation.