Oxide Scale Morphology of Carbon Steels Under Novel Reheating Conditions

As a result of work carried out within HYINHEAT, we are pleased to share the peer-reviewed open-access publication “Oxide Scale Morphology of Carbon Steels Under Novel Reheating Conditions”, published in steel research international.

Abstract

Steel slab reheating before hot rolling represents a significant source of CO₂ emissions in the steel industry. The introduction of alternative heating technologies, including hydrogen combustion, oxy-fuel combustion and electrical heating, could substantially reduce the carbon footprint of this process. However, these technologies also modify the furnace atmosphere and can therefore influence the formation and properties of the oxide scale that develops on the steel surface during reheating.

This study investigates changes in oxide scale morphology under different current and potential future reheating conditions. Four carbon steels with different elemental compositions were analysed using a thermogravimetric analyser at temperatures of up to 1250 °C. The resulting oxide scales were characterised using field-emission scanning electron microscopy to evaluate the steel–scale interface and pore structure, X-ray diffraction to identify and quantify iron oxides, and energy-dispersive spectroscopy to analyse the enrichment behaviour of secondary elements such as silicon, nickel and chromium.

The results demonstrate that changes in reheating atmosphere affect several characteristics of the oxide scale, including its morphology, porosity, adhesion and phase composition. By improving the understanding of steel oxidation under hydrogen-based, oxy-fuel and electrically heated conditions, the study provides valuable knowledge to support the transition towards more energy-efficient and lower-carbon steel reheating processes.