Corrosion Resilience of 2101 LDX Duplex Stainless Steels in Varying Sulphate Anion Concentrations

Abstract:

The general and localized corrosion resilience of 2101 LDX duplex stainless steel (2101ST) was assessed in specific concentrations of H₂SO₄ electrolyte by Potentiodynamic polarization, potentiostatic evaluation, open circuit potential analysis and optical illustration characterization. Data output shows 2010ST exhibited sufficient resistance to general corrosion (0.28 mm/y and 1.01 mm/y) at low concentrations of H₂SO₄ solution (1M and 2 M H₂SO₄) whose values correlates to polarization resistance of 42.47 Ω and 19.74 Ω. Further increment in H₂SO₄ concentration results in substantial increase in degradation rate which culminated at 58.32 mm/y at 6M H₂SO₄ and polarization resistance of 0.10 Ω. Due to the destructive action of SO₄^2- anions. Corrosion potential shifts indicates dominant anodic dissolution reactions with respect to H₂SO₄ concentration. Metastable pitting activity was observed on the plot following anodic polarization but prior to passivation of the steel. The metastable pitting current and passivation potential of the steel grew with increase in H₂SO₄ concentration. This weakened the localized corrosion resistance of the steel at higher H₂SO₄ solution. This is evident in the decrease in passivation range values plot configuration. Open circuit potential plots depict significant passivation of the steel at 1M H₂SO₄ solution compared to the plot at 6M H₂SO₄ which indicates strong tendency to corrode despite its thermodynamic stability. Optical images of 2101ST exterior after corrosion at 1M H₂SO₄ solution shows mild surface deterioration coupled with miniature corrosion pits. This contrasts the morphology of the steel at 6M H₂SO₄ which showed the presence of deep and enlarged, corrosion pits, and a badly etched surface showing the grain boundary coupled with a severely degraded exterior.

• Periodical: Materials Science Forum (Volume 1059)
• Pages: 55-60
• DOI: https://doi.org/10.4028/p-1o4829
• Online since: April 2022
• Authors: Roland Tolulope Loto*
• Keywords: Corrosion, H₂SO₄, Passivation, Pitting, Steel

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