Effects of mechanical deformation on the protection properties of coil coating products

The possibility of introducing some defects in shaping and forming metal sheets can decrease the performance of coil coatings products, reducing the advantages of this technology, which is relevant from an economical and environmental point of view. In this work are studied different coating products, containing environmentally friendly pigments (Ion Exchange Pigments), deformed atlons: bending and deep drawing. After the calculation of the strain induced by deformation, the samples were characterised by Electrochemical Impedance Spectroscopy in order to study the protective properties of organic coatings as a function of the imposed deformation. It was possible to compare the different coating cycles and to identify a maximum acceptable strain threshold for every material. In order to optimise the experimental approach, the data obtained using different deformation methods, but with a similar strain were compared, showing that the deep drawing deformation (cupping test) seems to be the simplest and the most useful way for an electrochemical characterisation of organic coated metal sheets after mechanical deformation. (C) 2000 Elsevier Science Ltd. All rights reserved.