Abstract
The mechanisms of metal dusting as it appears on different ferritic stainless steels and pure iron have been described in detail. A mechanism for metal dusting (MD) of chromia‐forming as well as alumina‐forming steels is proposed, based on results from laboratory exposures of 26Cr‐steel and FeCrAl‐alloy at 600–650°C for up to 5000 h in a synthesis gas low in water vapour, 25%CO + 3%H~2~O + H~2~. Metallographical examinations, FEG‐SEM, SEM‐EDX analysis and X‐ray diffraction, as well as thermodynamic calculations were made in order to identify and describe the different metal dusting processes. The work focuses on the role of carbides and oxides to explain the observations and give a description of the metal dusting phenomenon as it appears in engineering alloys. This mechanism was first observed and identified in a study of an austenitic stainless steel.
The driving force for steady state MD on pure iron and low alloyed steels is described and a secondary MD‐mechanism, carbon nanotube formation, is described in detail. With these additional results it is now possible to extend understanding of the MD‐processes to a wide range of engineering alloys.