Metal dusting phenomenon during carburization of FeNiCr-alloys at 850–1000°C

Three austenitic FeNiCr steels, G 4848, G 4852 and 36 XM, have been corroded in CH₄ + H₂ mixtures at 850, 900 and 1000°C. Under these conditions a new metal dusting phenomenon has been observed where closed cavities near the exposed surfaces of the alloys are filled with a powdery mixture of graphite, iron metal, chromium carbide and also in cases SiO₂. It is tentatively concluded that the powder is formed through the decomposition of (Cr, Fe)₇C₃.