Localized Corrosion of Chromium Coated Steel

The corrosion behaviour of Cr-coated steel with and without uniaxial deformation was investigated by polarization and scanning vibrating electrode technique (SVET). The Cr coating on low carbon steel is in two different thicknesses, 0.01 and 1.06 micrometers. The chromium-coated steel was elongated up to 25% strain. The results show that the Cr-coated steel has larger corrosion resistance than the uncoated steel. The corrosion resistance increases with the thickness of the chromium coating. The SVET results show that pitting does not initiate at all defects at the same time. The pitting process is unstable. After a pit is covered by corrosion product a new anodic site may start to be active. The uniaxial deformation results in more defects in the coatings and decreases the corrosion resistance of the Cr-coated steel in an environment containing chloride.