Pitting Corrosion Behavior of Q235 Carbon Steel in NaHCO3+NaCl Solution under Strain

Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-31 Cooperative journals: 《中国腐蚀与防护学报》

李阳恒 左禹 唐聿明 赵旭辉

Abstract： The effect of strain on the pitting behavior of Q235 carbon steel in solutions of NaHCO3+ NaCl was studied by means of potentiodynamic polarization measurement, EIS and XPS. The results show that in a solution of 0.2 mol稬-1 NaHCO3+0.01 mol稬-1 NaCl, a strain of 8% leads to an obvious increase of the pitting potential Eb of Q235 steel, but as the Cl- concentration increased, the difference between the Eb values of strain and strain free samples decreased. When the Cl- concentration increased to 0.1 mol稬-1, the difference of Eb values disappeared. Besides, strain caused lower impedance, smaller charge transfer resistance Rct and decreased the ratio Fe3+/Fe2+ in the passive film, thereby reduced the stability of passive film. The phenomenon that strain caused the increase of Eb was attributed to that the strain promoted the anodic dissolution of Fe which in turn promoted the preferential adsorption of HCO3- on the surface, as the result the harmful effect of Cl- on the passive film was inhibited. As the ratio HCO3-/Cl- in the solution decreased, the effect of HCO3- decreased and finally disappeared.

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