Effect of Forming Deformation on Corrosion Test Performance of Electroplated Zinc and Iron-Zinc Alloy Coatings for Automotive Sheet 862012

The effect of forming deformation on the corrosion performance of electroplated zinc and iron-zinc alloy coated steel was investigated. The materials were tested with (1) no deformation, (2) moderate deformation, and (3) high deformation. The formed specimens were painted, scribed, and exposed in three corrosion tests. Although significant morphological change (cracking) occurred in the deformed surfaces, the results of the corrosion testing showed that the forming had no effect on cosmetic corrosion performance. A paint adhesion evaluation revealed that forming had no effect on the paint adhesion on carbon steel, but adhesion loss increased with increased deformation on the iron-zinc coated specimens and decreased with increased deformation on zinc coated specimens. Significantly, in nearly all cases, the actual loss of adhesion for the iron-zinc-alloy coated samples was less than that on the zinc-coated or carbon-steel samples.