Crystallographic texture based analysis of Fe<inf>3</inf>O<inf>4</inf>/α-Fe<inf>2</inf>O<inf>3</inf> scale formed on a hot-rolled microalloyed steel

© 2015 ISIJ. Oxide scale formed on the strip surface during hot rolling has posed a serious obstacle to ensure a defect-free surface of steel products in an ecologically friendly way. Recently, an influential idea is that the tertiary oxide scale with a tailored texture can be expected to enhance surface quality and tribolgoical properties during particular lubrication. In this study, texture evolutions of magnetite (Fe3O4) and hematite (α-Fe2O3) in deformed oxide layers formed on a hot-rolled microalloyed steel were investigated by electron back-scattering diffraction (EBSD). Fe3O4 develops a strong θ fibre parallel to the oxide growth, and α-Fe2O3 has a dominant {0001}>101 0> texture component. This could be explained by surface energy minimisation during oxides growth and transformation between two oxides, which can also be affected by propagation of cracks along high angle grain boundaries in Fe3O4. Our data further demonstrate that a high thickness reduction (>28%) can reduce α-Fe2O3 wedging through Fe3O4 cracks, and tailoring Fe3O4 texture to {111} components can prevent the α-Fe2O3 growth titling 54.76° from the >001> crystal direction of Fe3O4. As such, these means can dramatically alleviate disturbance from 'red scale' (α-Fe2O3) during high-temperature steel processing