Basic Considerations for the Development of a Corrosion Test for Stainless Steels Used for Automotive Applications

In this work, the corrosion performance of stainless steel materials for application in the automotive industry has been evaluated by means of on-vehicle testing and laboratory cyclic corrosion tests. Additional laboratory measurements have also been performed in well defined exposure conditions. The results indicate that no cosmetic corrosion was observed upon on-vehicle exposures after 2 years exposure in Sweden and Germany and 5 years exposure in France. Cyclic corrosion tests were also performed in order to assess the corrosion resistance of different stainless steel grades. The results indicate large discrepancies in corrosion resistance when comparing the different cycles. This is explained by differences in chloride deposition, wet/dry cycle condition and way of deposition of the pollution on the samples. From the results it is obvious that cyclic accelerated corrosion tests that have been developed for assessing the performance of precoated materials cannot directly be used to assess the corrosion resistance of stainless steel. Hence, there is a need to develop or to adapt cyclic corrosion tests in order to evaluate the corrosion resistance of stainless steel.