Corrosion Behavior and Mechanism of Galvalume Steel Sheets in Simulated Acidic Atmosphere Environment

The mechanisms underlying corrosion in galvalume (GL) steel sheets in an acidic environment were studied using cyclic corrosion acceleration tests in a NaHSO₃ solution media. Corrosion kinetics were established using the loss-in-weight method. The corrosion morphology of the GL steel sheet surface was observed by SEM and confocal laser scanning microscopy. The composition of the surface corrosion products was analyzed using energy-dispersive x-ray spectroscopy, XRD, and XPS. In this environment, the thickness loss and time are the power functions of the relationship, and the corrosion rate is a deceleration process. No significant red rust was observed on the surface after a 120-d test due to the formation of a dense corrosion product layer with good inhibiting effect. The final corrosion products mainly comprised Al₂O₃, Al₂SO₄(OH)₄·5H₂O, Zn₄SO₄(OH)₆·4H₂O, and the soluble products ZnSO₄·xH₂O and Na₂ZnSO₄·4H₂O.