Transmission electron microscopy of high pressure metal dusted 316 stainless steel

Metal dusting is a serious limitation on the lifetime of materials used in modern petrochemical plants which are moving to the use of higher carbon activity environments to improve plant efficiency. A 316 stainless steel alloy has been subjected to accelerated metal dusting in the laboratory using temperatures and pressure typical of plant using 25%CO–75%H2 syngas at 450–650 °C and 40 bar. A precipitate and graphite based model for metal dusting in other environments has been evaluated in the newer more aggressive test conditions. Electron and X-ray diffraction have been used for the identification of the carbide and oxide precipitates. EELS TEM has been used for quantification of carbon levels. The orientation of graphite relative to austenite particles that survive intact into the coke has been examined using HRTEM.