Microtexture and Rolling Deformation Behavior Analysis of the Formation Mechanism Fe3O4 at the Interface Formed on Hot-Rolled High-Strength Steel

In order to better understand the formation mechanism of tertiary oxide scale in high-strength steel during hot rolling, the microtexture of the oxide layer has been characterized and analyzed by the electron backscatter diffraction (EBSD) method. The results show that the Fe3O4 phase in the oxide layer has a two-phase heterogeneous morphology, Fe3O4 in the oxide layer comprises columnar grains, and Fe3O4 near the substrate comprises spherical grains. As the reduction rate increases, the Fe2O3 layer is gradually wedged into the surface of the Fe3O4 layer. Fe3O4 forms a fiber texture at a reduction rate of 10%. The inner layer of the oxide scale comprises spherical grains, and Fe3O4 is preferentially nucleated and precipitated in the direction of Fe surface grains texture. With the increase in the reduction rate, the {112} directional slip system shows the lowest Schmidt factor value, so the grains with a low Schmidt factor exhibit higher stored strain energy. The formation of the spherical Fe3O4 seam layer close to the steel matrix is the result of the combined effect of the stress state at the matrix and ion diffusion.