Effects of Oxide Scales on Corrosion Behavior of Q235 Carbon Steel

Different structure scales were formed on the surface of Q235 carbon steel by isothermal temperature oxidation method at 750 ℃ in air and with different cooling methods. The micro-morphology of scales was inspected by SEM. Corrosion behaviors of Q235 carbon steel with different oxide scales were investigated in 0.5 mol/L NaCl solution by accelerated immersion corrosion test and electrochemical technique. The results show that the oxide scale changed the corrosion behaviors of Q235 carbon steel. The steel with oxide scale has the characteristics of localized corrosion. The steel with bare surface has the characteristics of general corrosion. The steel with different oxide scales had different corrosion characteristics. The oxide scale on air-cooled ateel is dense and continuous, but the oxide scale on air-cooled steel has a lot of defects. The oxide scale on air-cooled steel exhibits more excellent corrosion resistance compared with that oxide scale on water-cooled steel.