Effect of Temperature on Structure and Corrosion Resistance of Oxide Scale on Hot Rolled Strip

Abstract

Various structure scales at the surface of SS400 hot rolled strip were fabricated by heat treatment processes involving different temperatures. A simulation about the effect of various temperatures on the oxide scale structure during the coiling process was carried out. The structure and corrosion behavior of different oxide scales formed at the surface of hot rolled strip were investigated in sodium bisulfite (NaHSO3) solution by scanning electron microscope (SEM), X-ray diffraction (XRD), polarization curves and electrochemical impedance spectroscopy (EIS). The scale prepared at 550 °C is mainly composed of one layer of Fe3O4 phase. The scales prepared at 600 °C and 700 °C consist of the outer thin Fe2O3 layer and the inner (Fe3O4+Fe particles) layer. The scale prepared at 650 °C is mainly composed of Fe3O4 phase as well as a spot of Fe2O3 phase. The thickness of scale prepared at 650°C is observed to be more homogeneous than that of other scales and the bonding between the scale and substrate is found to be very strong. The experimental results clearly reveal that the hot rolled strip with scale prepared at 650 °C exhibits the most excellent corrosion resisting property in 0.01 mol/L NaHSO3 solution.

Effect of oxide scale structure on shot-blasting of hot-rolled strip steel

“…Parameters such as steel type, rolling speed, rolling temperature, cooling speed and coiling temperature, etc. will affect the oxide scale composition (Zhou et al, 2011;Gong et al, 2009). The oxide scale layer of ordinary carbon steel generally consists of three layers (Bonnet et al, 2003): the inner layer is a solid solution of FeO and Fe 3 O 4 , the middle layer is Fe 3 O 4 , and the outer layer is Fe 2 O 3 .…”