Abstract
ABSTRACTOxidation behaviour of an austenitic steel HR3C at 620∼650°C for 1000 h in steam with two different levels of dissolved oxygen (DO), 20 ppb and 5 ppm, was investigated by gravimetry, X-ray diffraction and scanning electron microscopy. Results showed that mainly a single-layered (Cr, Mn)2O3 scale was developed. The oxide growth followed near-power kinetics and was accelerated with DO concentration and exposure temperature. At the higher DO concentration, the formation of (Cr, Mn)2O3 with a much smaller size was favoured. Besides, the oxide scale became undulated and interfacial voids formed. Higher exposure temperature resulted in the growth of the (Cr, Mn)2O3 crystals and the change of their morphology from acicular to granular. Fe3O4 nodules and Ni-Cr spinel occurred at 650°C/5 ppm DO. Related oxidation mechanisms were discussed.
Published Version
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