Analysis of the influence of plastic deformation on the corrosion resistance of thin tin coated sheets

Thin tin coated steel sheets are still one of the most used material in the production of packages. Majority of these sheets are processed by drawing. Decreasing thickness of the thin steel sheets and the increasing required speed of drawing in the production of packages often lead to the loss of stability of plastic deformation, which demonstrates itself through the localization of deformation or the material failure of processed packaging sheet. Localization of deformation significantly influences the change in thickness, the porosity of tin protection layer and its integrity. Two grades of tin coated steel sheets were used for the experimental research. Their properties were examined using uniaxial and biaxial tensile test. After the plastic deformation, the sheets were exposed to the corrosive environment and the influence of the size of deformation and the localization of deformation on the corrosion resistance of thin packaging sheets was evaluated. Some particular cases of corrosion of so called twist-off caps were analyzed as well.