Papers by Author: Shi Ping Zhang

Abstract: When the pressure of CO₂ is 2 MPa, through the autoclave corrosion tests of annealed N80 steel specimens in simulated oil field water solution at different temperature, the mechanism of corrosion and the change rule of corrosion resistance with the change of temperature were discussed. In the autoclave tests, some iron elements of the specimens become Fe²⁺ ions and the Fe²⁺ ions go into the solution, which results in the corrosion weight loss. Scaling develops because the CO₃^2- ions in the simulated oil field water solution react with iron elements of the specimen. To QPQ treated specimens, with the increase of temperature, the compactness of the scaling increase, the corrosion weight loss and the weight of scaling decrease. In the same temperature, the corrosion weight loss and the weight of scaling of QPQ treated specimens are both lower than that of untreated specimens.

Abstract: By constant stress tensile test, the corrosion mechanism of high temperature QPQ treated 25CrMnMo steel specimen in H₂S environment was analyzed and discussed. The γ′-Fe₄N in the ε compound layer turns into corrosion substance in the test and expands. At the surface of the ε compound layer, the corrosion layer is visible. The compound layer breaks off in little blocks for volume expansion of the corrosion substance and the exterior tensile stress. The coefficient of diffusion of hydrogen atom in the ε compound layer is very low, that decrease the probability of the hydrogen-induced corrosion of high temperature QPQ treated specimens in H₂S environment.