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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 1000ϗ, it leads to a triple increase in the surface oxidation
rate, whereas the temperature increase to 1200ϗ results in an eightfold increase in the surface
oxidation rate. It is noted that, within the temperature range of 720-950ϗ, 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 600-1200ϗ.
Keywords: eutectoid steel, thermal gravimetric analysis, differential scanning calorimetry, oxidation, decarburization |
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