The oxidation of 18/8 type stainless steel in high pressure CO₂/2% CO

Abstract

Abstract The oxidation of a variety of 18/8 stainless steels in high pressure CO 2 /2% CO has been followed in the temperature range 550–650°C using intermittent weight gain measurement metallography, fractography and scanning electron microscopy. Duplex scales formed at an early stage of oxidation. The weight gain curves were analysed in terms of a two stage process, the initial stage exponentially approaching a slower secondary stage. The primary rate of duplex scale formation did not show the usual temperature dependence. Rather a maximum in the rate was observed at ∼600°C. Secondary rates were well established at 650°C and 550°C the secondary rate at 550°C, however, being higher than that at 650°C. Various spinels occurred and the results are explained in terms of the rate controlling process being cation diffusion through different inner spinels.