Influence of uniaxial deformation on surface morphology and corrosion performance of chromium-based coatings for packaging steel

Highlights: • ECCS was fully resistant to corrosion driven disbondment of a model organic coating in non-deformed and deformed states • Cathodic disbondment kinetics increase with the percentage of uniaxial strain applied for Cr(III) derived coatings. • Cathodic driven disbondment rates are suppressed with Cr oxide thickness increase, pre and post deformation. • Changes in coating morphology induced by deformation are assessed using a scanning electron microscope. • Hydrogen evolution kinetics are measured to assess the electrochemical availability of the underlying iron-based substrate post deformation. Chromium-based coatings on steel, cathodically electroplated from Cr(VI) and Cr(III) electrolytes, were studied to compare their corrosion resistance following application of uniaxial strain. An organic overcoat (PVB) was applied to strained samples and an in-situ scanning Kelvin probe technique was used to determine rates of PVB cathodic disbondment. The Cr(VI) derived coatings were fully resistant to cathodic disbondment post-deformation. The Cr(III) derived coatings exhibited increased rates of cathodic disbondment with increasing uniaxial strain. The Kinetics of cathodic disbondment are explained on the basis of coating morphology produced by deformation, and the exposure of underlying iron. The electrochemical availability of iron is estimated by measuring hydrogen evolution kinetics on cathodically polarised samples.