High Temperature Corrosion of Steel X15CrNiSi25-21 (1.4841) in a Mixed Gas Atmosphere – Sample Preparation and Damage Mechanism

Abstract

Abstract Steel 1.4841 was tested as a possible reactor material for a cracking process of anthropogenic resources under simulated laboratory conditions at 680 °C. The gas atmosphere present in this process contains HCl as well as H2S. In order to evaluate the corrosion behavior, metallographic sections were prepared from the corroded samples. The preparation for the SEM/EDS examination had to be performed under exclusion of water, as otherwise the readily water-soluble metal chlorides would not have been detected. A layered, porous structure of the corrosion products (oxides and sulfides of Cr) could be observed. The lowermost layer contains chromium and iron chlorides. Nickel could not be found in any of the corrosion products. In order to estimate the long-term resistance, aging tests were performed at 680 °C in an inert atmosphere for up to 1600 h before the actual corrosion tests. The formation of Cr23C6 and also of Ϭ phase could be evidenced by TEM. Compared to the non-aged samples, the chromium depletion caused by aging resulted in slightly increased corrosion rates.