Corrosion Behavior of Painted Zinc and Zinc Alloy Coated Autobody Sheet Steels

A number of commercially available zinc and zinc alloy coated sheet steels were tested in three different accelerated corrosion tests. Statistical analysis using two types of damage configurations, which included a gravel impinged preformed biaxially stretched postpainted dome and a conventional scribe, indicated that pure zinc coatings exhibited the best cosmetic corrosion resistance to stone-chip damage while pure zinc and zinc/iron coatings provided equivalent resistance to underfilm corrosion. The effect of test, paint damage and primer on the cosmetic corrosion performance of the various substrates is also presented.