Effect of Scratch Size on Hydrogen Permeation Behavior of Zinc Coated Steel during Wet and Dry Corrosion Tests

The influence of scratch size on the hydrogen permeation behavior of Zn coated steel during wet and dry cycle corrosion tests was investigated electrochemically. A size controlled scratch was formed on Zn coated steels with a pulsed YAG laser machining technique. The hydrogen permeation current was observed independent of formed scratch size. The periodic changes of the hydrogen permeation currents following the cyclic changes of the relative humidity were observed. After the tests, the red rust and zinc-hydroxychloride (simonkolleite) were observed at initially placement of NaCl solution. The total amount of permeated current did not proportionally increase with increasing the formed scratch area, indicating that the corrosion products played an important role in the hydrogen permeation behavior during wet and dry corrosion.