Mathematical Modeling of Decarburization and Oxidation during Reheating Process of SAE1070 Steel Billets

摘要

The SAE1070 steel grade, used especially in the automotive industry, has strict specifications and some of them are limits to oxidation and decarburization, which implies carbon loss through a variety of diffusion mechanisms. Temperature, atmospheric oxygen potential, carbon chemical potential gradient and time of high temperature exposure are some of parameters, that influence the extent of decarburization. Oxidation influences decarburization losses, in the metal/oxide interface, and as a result of this interface moves into the sample. During the reheating of billets for hot rolling, measures to contain oxidation to the minimum becomes a priority. In this work, the extent of oxidation and decarburization has been studied in the laboratory under industrial conditions as industrial scale experiments are expensive and not very practical. Mathematical modeling based on the results of laboratory experiments becomes attractive as this can be applied to industrial conditions. Isothermal tests for the evaluation of oxidation and decarburization were conducted in an electric furnace in the temperature range 600°C - 1100°C and time ranging from 2 hours to 48 hours. Decarburization and oxidation were measured by techniques such as weight change ue to removal of scale, micro-hardness testing and optical microscopy. Based on the methodology, an algorithm has been developed for assessment of oxidation and decarburization occurring in the industrial reheating of billets With minor adjustments, it is shown that, the model can be satisfactorily applied with reasonable accuracy.