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

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.

Corrosion of N10276 in a H2S, HCl, and CO2 Containing Atmosphere at 480 °C and 680 °C

“…The material N10276 was tested under conditions simulating a thermal cracking process of anthropogenic resources. Contrary to previous tested Fe-Cr-Ni alloys [2,3,[15][16][17][18][19], N10276 additionally contains the alloying element molybdenum (16 wt.%) and only very little iron (5 wt.%). Thus, the material showed a different corrosion behavior in the HCl and H 2 S containing atmosphere, which was critically discussed in a corrosion model.…”

“…Three corroded samples were used for the mass loss determination, one was cold mounted in epoxy resin and polished water-free with 3 µm diamond grit before they were investigated by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The water-free polishing was necessary to preserve water-soluble corrosion products to visualize unaltered cross sections of the corroded samples [18]. In this study, corrosion experiments were performed with the material N10276 (also known as 2.4819 or NiMo16Cr15W).…”

High temperature corrosion behavior of alloys in reducing HCl and H2S containing environments: Thermodynamical and experimental assessment

“…SEM/EDX mappings, which show the corrosion structures of the ferritic and austenitic alloys, either can be found in previous studies [ 6,18–22,24,25 ] or for some selected conditions on representative examples of K90941 and N08811 in Figures 7–14. SEM/EDX mappings of K90941 and N08811 for the remaining conditions can be found in the Supporting Information Materials.…”

“…Nevertheless, they are helpful for first estimations of the type of material that may show protective behavior in a particular atmosphere. [23,27,28] The high-temperature corrosion behavior in reducing HCl and H 2 S containing atmospheres of several alloys, ranging from low-alloyed ferritic K90941 up to highly alloyed austenitic N10276, was investigated at various conditions during previous studies [6,[18][19][20][21][22]24,25,29,30] and different corrosion models were generated. [18,20,24,25] In Table 1, an overview of all performed experiments in reducing HCl and H2S-containing atmospheres is presented and corresponding references to the published results are denoted.…”

“…In contrast to many fundamental processes of high‐temperature corrosion that are nowadays understood, for complex technical atmospheres and sophisticated technical materials, this knowledge can only be used to make approaches and to interpret observed tendencies. [ 6,18–25 ] Thus, there is still a strong need for intensive research in the field of high‐temperature corrosion, based on experimental investigations, to describe the actual behavior of the materials and the corrosion mechanisms behind this.…”