Corrosion Products and Formation Mechanism During Initial Stage of Atmospheric Corrosion of Carbon Steel

The formation and development of corrosion products on carbon steel surface during the initial stage of mospheric corrosion in a laboratory simulated environment have been studied by scanning electron microscopy and Raman spectroscopy. The results showed that two different shapes of corrosion products, that is, ring chain, were formed in the initial stage of corrosion. MnS clusters were found in the nuclei of corrosion products the active local corrosion sites. The ring-shaped products were composed of lepidocrocite (gamma-FeOOH) and (gamma-Fe(2) O(3)) transformed from lepidocrocite. The chain-type products were goethite (alpha-FeOOH). A formation mechanism of the corrosion products is proposed.