The influence of magnesium content on the structure and morphology of coating during hot galvanizing process

Hot dip galvanizing is one of the main methods of steel protection. In general atmospheric conditions, the corrosion resistance and coating thickness of the batch galvanized layer can meet the requirements for use, but under the conditions of Marine environment and industrial pollution environment, the galvanized layer is usually used at 610g per square meter. Due to the protection of galvanized layer, it is difficult to meet the requirements for use. Therefore, we need to find out how to improve the corrosion resistance of the galvanized layer, so it is an urgent need to develop a better corrosion resistant zinc-based alloy coating.

In order to develop zinc-based alloy coatings with better corrosion resistance, the consumption of zinc resources should be reduced in order to adapt to the development of the future era. The researchers found that magnesium is of great concern because it strengthens the grain boundary, refines grain size and improves corrosion resistance of the coating. Therefore, the researchers thought of adding a small amount of magnesium in the zinc solution to improve the corrosion resistance of the coating, and studied the effect of adding a small amount of magnesium in the zinc solution on the surface appearance and tissue structure of the coating.

According to the analysis of several groups of experiments by experts, first, the addition of trace magnesium in zinc solution has a significant impact on the morphology of the coating. The grain size of hot-plated steel plate can be significantly reduced with the increase of magnesium content from 0.05% to 0.3%. Second: the addition of magnesium in zinc solution to less than 0.3% will not affect the main composition of the coating. But it will reduce the size of each intermetallic compound and change the appearance of intermetallic compound layer.