The behavior of Crofer 22APU steel in H-2/H2S atmosphere

In this paper authors present results of sulfi dation of Crofer steel in H-2/H2S. The high temperature corrosion behavior of Crofer 22APU and preoxidized Crofer steel were studied in the temperatures range 600-900 degrees C in H-2/H2S atmospheres. Sulphur partial pressures (p(S2)) was in the range 10(-7) to 10(-1) Pa. The kinetics show that the sulfi dation process of preoxidized samples was going slower. Morphology of the scales (surface and cross section) have been observed by SEM. Phase and chemical composition have been studied by EDX and XRD methods. It was found that scale formed on Crofer steel was built with porous sulphides and in some case (p(S2), temperature) the internal sulfi dation of steel was observed. The phase analysis of the scale reveled that it is composed mainly of a sulphides of iron and chromium but in low sulfur partial pressure only chromium sulfi de was detected.