Relation Between Mechanical Instabilities and Corrosion Sensitivity of Aluminum Body Cans Surfaces

Аннотация

In this work we investigated the mechanical and corrosion behavior of aluminum can bodies. The results obtained show homogeneous distribution of intermetallic particles. The magnesium presence, in the surface of the can bodies, causes instabilities in the tensile curves and provokes localized corrosion surrounding the split up, fissured, sheared and non sheared intermetallic particles by dissolution of magnesium, in the Keller reactant and chloride solution, in the discontinuities of varnish in the inside of can bodies. It is also seen that the localized corrosion observed is caused by a lateral propagation mode. The heterogeneity of thickness of the can body surface, due to the deep drawing, causes an increase corrosion sensitivity of the can body surface and cancel the sheet anisotropy. The Lankford coefficient is very low in the three directions and the planar coefficient in some area takes negative values. It is also seen that all the observations showed an increase on the global strain inducing a premature beginning of diffuse necking. The zones where the diffuse necking appears are sensitive to localized corrosion.