The Comparative Performance of a Non-Chromium Post-Treatment Evaluated by Accelerated Corrosion Tests on Automotive Sheet Steels

The accelerated corrosion test performance of various automotive sheet steels was used to determine the effectiveness of chromium-containing (Cr⁺³/Cr⁺⁶) and chromium-free post-treatments. Laboratory prepared panels treated with state-of-the-art pre-treatment systems, followed by either a chromium-containing or a chromium-free post-treatment, were painted with cathodic e-coat and topcoat systems being used by different automobile manufacturers. These panels were then tested in a number of accelerated corrosion tests used by the automotive industry. The test results showed that a chelating-polymer, chromium-free post-treatment gives corrosion performance equal to that of a post-treatment containing chromium.