Effects of the Presence of Water Vapour on the Oxidation Behaviour of Low Carbon-Low Silicon Steel in 1 %O_2-N_2 at 1073 K

摘要

The effect of water vapour additions in the range of 2.5-24.8 % on the oxidation behaviour of a low carbon and low silicon steel in 1 %O_2-N_2 at 1073 K (800 °C) was examined. It was found that the characteristic of steel oxidation was completely changed by addition of water vapour in the atmosphere. First, the kinetics was changed from non-parabolic to parabolic. Second, the scale formed in 1 %O_2-N_2 for 30 min or longer was easy to spall upon cooling whereas the scales formed in the water-vapour containing atmospheres did not spall easily. Third, additions of 2.5-10 % of water vapour in 1 %O_2-N_2 resulted in the formation of numerous depressed locations in the scale, but the scale-steel adherence in the areas surrounding the depressed locations was very much strengthened. Finally, additions of 17.2 and 24.8 % of water vapour in the atmosphere prevented both scale spall?ation upon cooling and formation of depressed areas in the scale. The mechanisms of forming various scale structures and the roles of water vapour additions under different conditions were discussed.