Modern approaches for study of eutectoid steel oxidation and decarburization


This paper describes the results of a laboratory study into the high-temperature surface oxidation and decarburization of eutectoid steel performed using thermal gravimetric analysis which makes it possible to understand the steel surface oxidation kinetics in non-isothermal conditions as the steel specimen is continuously heated to a specified temperature. An exponential relationship is obtained between the heating temperature and the iron loss in steel. A relationship is established between the heating temperature applied and the surface oxidation rate observed in a eutectoid steel specimen. It is shown that when the temperature of the specimen is raised from 900 to 1000°С, it leads to a triple increase in the surface oxidation rate, whereas the temperature increase to 1200°С results in an eightfold increase in the surface oxidation rate. It is noted that, within the temperature range of 720-950°С, the phase transformations observed are accompanied with intensified scale formation and surface carbon depletion. Using the emission spectrometry technique, the concentration of carbon is determined in the surface layer in relation to the heating temperature and time. The results obtained indicate that eutectoid steel is subjected to an intense surface decarburization at the temperatures of 600-1200°С.