Abstract: | AbstractWe have studied the oxidation behavior of conventional austenitic stainless steels using same small amounts of Y as is added for deoxygenation and desulphurisaton in steel making.The direct observation and analysis of the oxide scale formed on 19Cr–10Ni–l .5Si steels with and without small amounts of Y at high temperature have been carried out using several types of equipment. The following results were found: (1) Steel with 0.03Y showed good resistance to oxidation at l,000°C. (2) Oxide scale was composed mainly of Cr oxide, and Si oxide was also detected at the oxide scale–metal interface and in the internal oxides. The Si oxide formed a network cell structure in the inner oxide scale with deeper internal penetrations. The steel with Y formed a uniform oxide scale in every oxide layer. (3) Small amounts of Y and Si were detected at the grain boundaries of the inner oxide scale, but no Y was detected in the oxide grains. The beneficial effect of Y addition was more notable in the Si containing austenitic stainless steels, as the existence of Y or Si prevents the diffusion of cations and anions through the oxide grain boundaries. As consequence, the steel treated with Y showed good resistance to oxidation. |