Research On High Temperature Oxidation Behavior Of Rare Earthlow-alloysteel

In the process of heating, oxidation phenomenon is happened in the steel surface.oxidation film of steel surface made yield is lowed, the performance of the steel isinfluenced, the quality of steel is reduced, a large amount of energy and resources is wasted.Study how to reduce the oxidation of steel in the process of production is greatsignificance.In this paper, the experiment was given priority to, the oxidation experiment wastested by adding weight method, high temperature oxidation was conducted in airatmosphere at950℃、1050℃、1150℃and1250℃, A low-alloy steel consisting oflanthanum-cerium rare earth was0%,0.0095%,0.0134%(mass fraction), oxidation timewas set to30min,120min and12h. Based on the experimental data, oxidation kineticscurve was drawn, and oxidation rate constants and oxidation activation energy werecalculated. The influence of chemical composition, heating temperature, holding time andother factors of low alloy steel in high temperature was analyzed, the oxidation kinetics oflow alloy steel with different contents of rare earth was studied, morphology of the surfaceoxide film on the surface and cross section was observed, to explore the mechanism of rareearth in low alloy steel in high temperature oxidation, and provide a theoretical basis forthe practical application.The results show that in air atmosphere, the isothermal oxidation kinetic curves of950℃,1050℃,1150℃and1250℃all conform to the parabolic laws and the oxide filmhas the protective effect. The reaction activation energy of the low-alloy steel is increasedand the oxidation rate constant is reduced by added rare earth. So, the high-temperatureoxidation resistance of the steel is improved, and, for the steel with higher content of rareearth, the high-temperature oxidation resistance is stronger. After2h oxidation of rareearth containing0.0134%samples and0.0095%steel oxidation activation energy increasedby97%and63%than no rare earth, and the rate constants were decreased by48%and20%. Under the atmosphere of air, when the oxidation temperature to1250℃, oxidation time in65minutes, low alloy steel oxidation kinetics is followed linear law and the oxidefilm is not protective, reaction rate is controlled by interfacial reaction, the more rare is, thefaster the oxidation rate is, and the addition of rare earth is not conducive to improving theoxidation resistance of low alloy steel. The oxidation time exceeds65min, the oxidationkinetics of low alloy steel obeys parabolic law, and the oxide film has a protective effect,the reaction rate is controlled by diffusion, the more rare earth is added, the better theantioxidant activity is. By adding the lanthanum-cerium rare earth compound, the grains inthe surface oxidation films of the low-carbon and low-alloy steel are refined and theadhesion between the oxidation films and the matrix is strengthened. So the oxidation filmsare not easy to fall off, which is beneficial to improving the oxidation resistance of the steel.And adding rare earth can not change the composition of the oxide film.