Conceptual

Steel Color Changes by Oxidation Layer Thickness in Heating Metals

Steel color changes during heating result from thin-film interference caused by varying thicknesses of surface oxidation layers reacting with atmospheric oxygen. This phenomenon establishes a direct correlation between visual spectral reflectance and specific temperature ranges, allowing the identification of thermal states below 427°C based on oxide film properties rather than incandescence. The theory applies to ferrous metallurgy within physics, utilizing principles of light reflection absorption and crystalline structure transformation via oxidation kinetics.