Effect of Hydrogen on Hydrogen Permeation and Stress Corrosion Behavior of Low Alloy Steel in Acid Gas Field

The effects of hydrogen concentration on hydrogen permeation and stress corrosion cracking behavior in 80SS low-alloy tubing steels in a saturated CO2 simulated produced water environment were explored by electrochemical hydrogen permeation, slow strain rate tension and stereo microscope, SEM. The results show that the acidity and the hydrogen permeation parameters i(infinity), D and C-0(H) are both increased with the raise of the concentration of H+, which contributes to the diffusion behavior of hydrogen atoms. Since the synergistic effect of tensile stress and hydrogen atom, the fracture time of 80SS low alloy steel is reduced by nearly 50% compared with the tension in air, and the change occurs from ductile fracture to brittle fracture. As the hydrogen concentration of the solution increases, the mechanical damage of the steel and the stress corrosion sensitivity strengthen. Before and after pre-charged hydrogen the index I-delta, changes from 3.16% to 8.49% when 80SS steel is stretched in a medium containing saturated CO2. Pre-charged hydrogen promotes the stress corrosion cracking sensitivity of the sample. When stretched in saturated CO2 produced water containing 1wt% HAc, the microscopic morphology before pre-charged hydrogen shows a river pattern with quasi-cleavage fracture characteristics. Discontinuous cracks and. small pores are distributed with fiber area of 80SS steel of the pre-charged hydrogen. Compared with before pre-charging, pre-charged hydrogen improves the plastic properties of the steel and reduces the stress corrosion cracking sensitivity of the steel.