Abstract
We have developed a new atmospheric corrosion test device that can control the deposition rate of sea salt particles. By using this device, certain amount of seasalt particles were attached on the low alloy steel and the progress of atmospheric corrosion was observed by both the super Kelvin force microscope and Kelvin force microscope under various relative humidity conditions. The results showed that thin liquid film was formed around the corrosion part when corrosion occurred at high relative humidity. After the specimen surface was covered with thin liquid film, Cl− ion can move to the corroding part to increase the corrosion rate.