Sustained effect of remaining cementite on the corrosion behavior of ferrite-pearlite steel under the simulated bottom plate environment of cargo oil tank

This investigation aims to study the sustained effect of remaining cementite on the corrosion of ferritepearlite steel in an acidic chloride solution (i.e. simulated bottom plate environment of cargo oil tank). The results show that the corrosion rate of ferrite-pearlite steel was continuously accelerated with extending the immersion time, caused by the continuously enhanced galvanic effect between the remaining lamellar cementite and exposed ferrite phases. Electrochemical impedance spectroscopy (EIS) data further indicated that the promoted dissolution of ferrite phases was controlled by charge transfer process. Meanwhile, the hydrogen evolution reaction occurred on cementite was controlled by the diffusion process. (C) 2016 Elsevier Ltd. All rights reserved.