Atmospheric corrosion behavior of weathering steels in initial stage

The behavior of the initial stage of atmospheric corrosion for weathering steels at 40 "C and 100% RH was investigated. The kinetics of atmospheric corrosion was found to obey Exponential law. Then values of weathering steels decrease when the content of Cu increases. The Cu helps to decrease corrosion rate of wheathering steel. The formation and development of corrosion products on weathering steel surface during the initial stage of atmospheric corrosion in a laboratory simulated environment have been studied by scanning electron microscopy (SEM) and Raman spectroscopy. The results showed that two different shapes of corrosion products, i.e. cluster and chain like particles, were formed in the initial stage of corrosion. The cluster products were composed of lepidocrocite (γ-FeOOH) and maghemite (γ-Fe₂O ₃) transformed from lepidocrocite. The chain like particle products were goethite(αFeOOH). A formation mechanism of the corrosion products is proposed.