Quality assessment of a mechanically deformed silicon polyester coated galvanised steel system

In this paper the influence of a mechanical deformation on the corrosion behaviour of a silicon polyester coated galvanised steel is investigated. The electrochemical behaviour of samples subjected to several degrees of uniaxial elongation (1-10% of total strain) is compared with the one of the samples bent over different mandrel diameters. First, the coating aspect of the different types of samples was investigated, by optical microscopy and with scanning electron microscopy (SEM). Strain effects causes damage up to the formation of cracks in the coating. Further, a relationship between the strain introduced by uniaxial deformation and the strain caused by bending of the sample could be formulated. Finally, the influence on the corrosion resistance after uniaxial deformation is compared with that caused by bending deformation. To conclude, it was possible to confirm the theoretically formulated relationship between uniaxial and bending deformation by means of microscopy and by electrochemical techniques. (C) 2000 Elsevier Science S.A. All rights reserved.