Corrosion behavior of 20# steel at initial stage under the (CO₂/aqueous solution) gas-liquid two-phase plug flow condition

The corrosion behavior of 20# steel at initial stage under CO₂/H₂O gas-liquid two-phase plug flow conditions was studied through weight loss, SEM, EDS, XPS methods. The corrosion rate results indicated that there was an obvious deceleration transition at the early stage of corrosion process. The difference of corrosion rate under different CO₂ pressures decreased with the extension of corrosion time. The precipitation of corrosion products started from the defects area of the pipe wall surface or the crystal interface, and the corrosion products extended to contact each other with the extending time. The corrosion products grew into the flocculated corrosion products on the surface of acicular corrosion products layer deposited preliminary with the extending corrosion time. The corrosion products on the bottom pipe wall grew faster than that on the top pipe wall. The main phases among the corrosion products layer were Fe₃C, FeCO₃, FeOOH and Fe₃O₄, and there was no polygonal FeCO₃ appeared. (paper)