Effect of coiling temperature on oxide scale of hot-rolled strip

The influence of the coiling temperature, ranging from 550 to 570℃, on the morphology and the phase composition of the oxide scale formed on the microalloyed low carbon steel for automobiles after hot strip rolling was investigated. Physicochemical characteristics of the oxide scales were examined and their formation mechanism was discussed. Thickness of the oxide scale is in the range of 8-11μm and decreases with a decrease of coiling temperature. The microstructure and phase composition, XRD analysis shows a large amount of magnetite (Fe3O4) and some sparse hematite (Fe2O3) exist on the surface of hot rolled strip when the coiling temperature reduces from 570 to 550℃. The coiling temperature substantially affects the internal microstructure and magnetite phase.