Effect of Temperature on Corrosion Behavior of Carbon Steel in Pollution-free Atmosphere with High Relative Humidity

The corrosion performance and the effect of temperature on the corrosion behavior of carbon steel were studied by analyzing corrosion rate,surface morphology and corrosion products.The corrosion rate of carbon steel increased with increasing temperature.During the corrosion period of 456 h in pollution-free atmosphere with 95% relative humidity,the mass gain followed exponential growth law and only cellular corrosion products appeared at 20 ℃,while the mass gain followed exponential decay law and nodular corrosion products were observed at 30 ℃ and 40 ℃.Nodular corrosion products included cellular and granular corrosion products.In atmosphere with high relative humidity,the water droplets formed on the surface of carbon steel firstly.Fe was dissolved at the center of the water droplet and oxygen was reduced at the edge.Then cellular corrosion products were produced at the center of the water droplet and it was found that the granular corrosion products grew around cellular corrosion products.γ-FeOOH and α-FeOOH were detected in the rust layer,and increased at higher temperatures.