Research On Oxidation Behavior Of Carbon Steel At Simulated Reheating And Hot-rolled Process

Reheating and hot-rolled process is an obligatory procedure of steel manufacturing. Oxidation would occur and oxide scale can be formed on the surface of steel due to the interaction of high temperature and oxide atmosphere. The condition of the oxide scale, including thickness, composition, structure and defects, directly determines the dephosphorization performances of thick plates and the final surfacial quality of hot-rolled production. Alloy elements and hot-rolled process parameters influence the high-temperature oxidation behaviors of steel and the state of oxide scale. Based on the hot-rolled carbon steel production, the researches of high-temperature oxidation behaviors at reheating and hot-rolled process were characterized by TGA, XRD, SEM/EDS and other technical methods.The oxidation kinetics of seven kinds of hot-rolled carbon steel oxidized at 860℃-1200℃in air basically follows the parabolic rule and appears deviation partially at higher temperature. That's mainly because the alloy elements are involved into great changes between the oxide scales and the state of matrix interface, which makes the oxide scale blistering and splitted. Oxidation temperature and oxidation time are critical factors influencing the thickness of oxide scales. The oxidation kinetics between 1100℃and 1200℃can be divided into two stages—the initial rapid transient oxidation stage and subsequent steady oxidation stage while the oxidation rate for the steady stage would increase with the increasing temperature. The oxidation rate of GL-A32 is slightly higher than that of B610E and the oxidation activation energy are 108.98 KJ/mol and 112.36 KJ/mol respectively. The oxide scale formed at 1100℃and 1150℃was grey-black, blistering in large areas, and also comparable thinner and easy to remove. The oxide scale formed at 1200℃, however, was light-grey and of higher hardness.The analysis of oxide scale of GL-A32 formed at reheating process and manufacturing site indicates that the thickness of oxide scale is 2 mm and the grain size is 50μm approximately. Si enrichment occurs at the oxide scale and matrix interface and the analysis of cross-section indicates that Si mainly appears in the inner oxide scale and interface between oxide scale and matrix, which has a great corresponding relation with low melting point and liquid flowing character of Fe₂SiO₄...