Oxide Scale Formation on Low-Carbon Steels in Future Reheating Conditions

Abstract

The mitigation of CO2 emissions is one of the major areas of research in iron ore-based steelmaking. In this study, four simulated current and potential future reheating scenarios with different fuel and oxidizer gases were studied regarding the amount of oxide formation and the adhesion of the steel–oxide interface: (1) methane–air; (2) coke oven gas–air; (3) hydrogen–air; (4) and an oxyfuel scenario with 50:50 methane/hydrogen as fuel gases. Isothermal oxidation tests were conducted at temperatures of 1150, 1230 and 1300 °C. Four low-carbon steel grades were tested in the previously mentioned gas atmospheres. The structure and composition of the formed oxide scales was analyzed with FESEM-EDS microscopy. The amount of oxide formation correlated with the water vapor content of the gas atmosphere for all four steel grades; however, notable differences were found between individual steel grades regarding the degree of oxidation increase. No clear evidence was found of the gas atmospheres affecting the adhesion of oxide scales to the steel substrate. The adhesion of the interface was mainly determined by the content of silicon in the steel grade and the test temperature.