Corrosion characteristics of low-carbon cast steel ZG230-450 in chloride-sulfate atmospheric environment.

Abstract

In the present paper, the corrosion behavior of ZG230-450 in chloride-sulfate atmospheric environment was studied, comparing with ordinary low-carbon steel Q235. Long-term and short-term corrosion tests were conducted, the corrosion products of the materials were observed and tested by scanning electron microscope and X-ray diffraction, and the corrosion rate and pitting corrosion behavior of the materials were studied by electrochemical test. The test results show that (1) the corrosion products of Q235 are mainly composed of γ-Fe₂O₃, γ-FeOOH, and α-FeOOH, while corrosion products of ZG230-450 are mainly composed of Fe₃O₄, γ-FeOOH, and α-FeOOH; (2) in the early stage of corrosion, the corrosion rate of ZG230-450 is higher than that of Q235. When the concentrations of Na₂SO₄ and NaCl solutions are both 3.5%, the self-corrosion potential value and polarization resistance of ZG230-450 are - 0.706 V and 324.75Ω, while the Q235 are - 0.687 V and 1080.0Ω, respectively. (3) ZG230-450 has better pitting corrosion resistance than Q235 in the same corrosive environment. When the Na₂SO₄ and NaCl solution concentrations are both 3.5%, the pitting potentials of ZG230-450 and Q235 are - 0.578 V and - 0.558 V.