Experiment On High-temperature Oxidation Kinetics Of U71Mn Steel

Research on the surface defects of iron and steel during the heating process in the field of material processing has been a focus. The oxide scale is the major defect of steel surface quality, and is also one of the main reasons leading to the loss of its mass. It directly affects the rolling yield of the steel.In this paper, it has been deeply studied that the relationship of heating temperature, heating time and the oxidation atmosphere with the surface oxidation of heavy rail steel, in view of the surface oxide was very serious when steel through the heating process, combined with the real heavy rail steel processing technology of rail steel factory in Baotou Steel Group, using U71Mn steel as the main object of study. Purpose is to clarify the heavy rail steel oxidation kinetics based on those studies and to improve product rolling yield. Study was laboratory-based. It uses weight gain method for continuous weighing of samples. It was calculated that the increased weight per unit area of the test specimen based on the experimental record. Gain curves plotted. Regressions analyze the curve. Gain the kinetics regulation between heating time, heating temperature and the surface oxidation situation. Combined with the data obtained in different oxidation atmosphere, analyze its influence to the oxidation.Under the air atmosphere, three experimental weight gain curves of the three kinds of heating systems, which are rapid heating-up, typical heating-up and slow heating-up, are protracted, after 260min heated, oxidation rates were 4.6%, 3.4% and 1.3%; In a simulated furnace atmosphere, the oxidation rates were 3.1%, 1.7% and 0.6%. Oxidizing atmosphere significantly affect the oxidation rates.In constant temperature experiment from 900℃to 1300℃, in air atmosphere, the average oxidation rate increased from 0.04 to 0.96 mg/cm2·min, when temperature lower than 1100℃, oxidation rates are slow, and then became much faster, 1100℃is the inflexion; in a simulated furnace atmosphere, the average oxidation rate increased from 0.01 to 0.81mg/cm2·min, the rate change inflexion is 1150℃. Oxidizing atmosphere significantly affect the oxidation rate. In the simulated furnace atmosphere, at 1200℃and 1300℃, the weight gain curves have an inflexion. The weight gain curve before the inflexion is steep. Followed the penetration of oxygen inhibits by dense oxide layer, oxidation rate became moderated, and then weight gain curve became slows. The results support available data for the exploration of the high-temperature oxidation kinetics in the heating process. It also provides a reliable theoretical basis to control the high-temperature oxidation of steel in the actual production, and to improve the heating process. It has important practical significance for the iron and steel enterprises economizing energy.