2012 Volume 61 Issue 2 Pages 64-71
It is verified that corrosion resistance of pre-coated steel sheets, coated with various coating materials, is mainly depended on thickness of topcoats, a type of anticorrosive pigments used in primers and an amount of accumulated salinity thorough a set of 44 months outdoor exposure tests. Results of the exposure tests showed almost no correlation with test results in the test conducted according to salt splay test and CCT-JASO-M609, widely accepted as an accelerating test method for evaluation of corrosion resistance. A series of analysis with SEM and EPMA on sections of edge creep area has revealed that there is a clear difference in corrosion development between these test methods. Since the salt splay test and CCT-JASO-M609 specifies a test condition where corrosion products cannot easily prevent further proceeding of corrosion, we presume that sacrifice corrosion cells composed of steel and plated steel substrates can stably exist for a long time in the test according these accelerated corrosion tests.