摘要
Carbon dioxide corrosion behavior of low-alloy pipeline steel with 1% Cr exposed to CO2-saturated solution was investigated by immersion experiment. SEM, EDX, TEM, EPMA and XRD were utilized to investigate the microstructure, corrosion morphologies, corrosion phases and elements distribution of corrosion scale. The results demon strate that the microstructure of tested steel consists of ferrite and carbides. During the corrosion process, ferrite dissolves preferentially, leaving carbide particles behind. The residual carbide particles may promote the nucleation of FeCO3 crystal. The phase comprising of the inner layer is Cr compound, and the one of the outer layer is FeCO3. The formation process of corrosion scale can be illustrated as follows： Firstly, a thin scale consisting of thin inner layer and outer layer is formed, which represents poor corrosion resistance; then, the inner layer changes little, once it has been formed, and the outer layer becomes thick and compact, which demonstrates that a fine corrosion resistance is obtained. The chemical elements of chromium and molybdenum accumulate in the inner layer of corrosion scale. The corrosion behavior of low- alloy steel based on microstructure and morphology characterization is also discussed.
Carbon dioxide corrosion behavior of low-alloy pipeline steel with 1% Cr exposed to CO2-saturated solution was investigated by immersion experiment. SEM, EDX, TEM, EPMA and XRD were utilized to investigate the microstructure, corrosion morphologies, corrosion phases and elements distribution of corrosion scale. The results demon strate that the microstructure of tested steel consists of ferrite and carbides. During the corrosion process, ferrite dissolves preferentially, leaving carbide particles behind. The residual carbide particles may promote the nucleation of FeCO3 crystal. The phase comprising of the inner layer is Cr compound, and the one of the outer layer is FeCO3. The formation process of corrosion scale can be illustrated as follows： Firstly, a thin scale consisting of thin inner layer and outer layer is formed, which represents poor corrosion resistance; then, the inner layer changes little, once it has been formed, and the outer layer becomes thick and compact, which demonstrates that a fine corrosion resistance is obtained. The chemical elements of chromium and molybdenum accumulate in the inner layer of corrosion scale. The corrosion behavior of low- alloy steel based on microstructure and morphology characterization is also discussed.
基金
financially supported by National Key Technology Research and Development Program of the Ministry of Science and Technology of China during the ‘‘12th Five- Year Plan’’(Grant No. 2011BAE25B03)
