Metal dusting corrosion of austenitic 304 stainless steel

Metal dusting is a severe form of corrosive degradation of metals at high temperatures (400-900°C) in carbon-supersaturated gaseous environments (a_c > 1). Fe, Ni, and Co base high-temperature alloys and steels are all susceptible. The corrosion manifests itself as a breakup of bulk metal to metal powder; hence, the term metal dusting. In the present study, metal dusting corrosion of 304 stainless steel (SS) is simulated in high carbon activity environments (Co-H₂) over a temperature range from 550 to 750°C. 304 SS corrodes by transfer of carbon and its subsequent diffusion and precipitation in the steel interior pursuant to local rupture of a protective surface oxide film. The focus of this research is to advance the understanding of the corrosion mechanisms of this type of steel by characterizing interfacial processes at the nanometer level. In addition to the effect of temperature and the role of surface finish on corrosion, the mechanistic aspects of metal dusting are discussed with particular attention to stages of micro-structure evolution as degradation proceeds.