High-temperature corrosion of austenitic alloys in HCl and H2S containing atmospheres under reducing conditions

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

“…During several studies, experimental know-how in the field of reducing HCl-and H 2 S-containing environments was gained (Table 1) and different corrosion mechanisms for diverse alloys under different conditions were developed. [18,20,24,25] These mechanisms are mainly based on practical observations and experience and only less on thermodynamic data. This is due to the complexity of these mixed gas atmospheres, the impact of volatile corrosion products, and the ever-changing conditions within the corrosion layer, which made it hard to predict the actual corrosion behavior.…”

“…In the high-H 2 S mixture, chromium was identified to be beneficial by slowing down the corrosive attack at 580°C (Figure 5), among others due to the formation of FeCr 2 S 4 . [21,25] The favored reactions of chromium with the gas phase as indicated in Table 7 and the less pronounced behavior of metal chlorides as indicated by quasi-stability diagrams (Table 8), might explain this behavior. The high corrosion rates of K90941 can be attributed to the nonprotective effect of iron sulfide compared with that of chromium sulfide, whereby the corrosion process can proceed faster.…”

“…x [21,25] x [20,25,29] x [21,25,29] x [19,29] x [25] x [25] x [25] x [21,25] x [25] x [21,25] N06600…”

“…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][19][20][21][22][23][24][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.…”

“…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.…”