Defect analysis and measures of surface particles on hot dip galvanizing steel products

The steel products can have a life of more than ten years, or even several decades, and have good corrosion resistance after being treated with hot galvanizing. Low investment and simple process. Therefore, hot dip galvanizing has become the most extensive anti-corrosion method of steel products. But there are small hard particles attached to the surface of steel, which we call surface particles. So why are there particles on a hot galvanized surface?

After the testing and research analysis of experts, we know that the basic cause of the surface particles raised by galvanized products is that the surface of the substrate contains iron chips, and a large number of iron chips are connected to the substrate. When the iron chips enter the zinc pot, they react with the zinc solution to form the explosive structure of zinc-iron compounds. In addition, these explosive tissues are thick and grow upward, causing the surface to bulge with particles. The iron scrap on the substrate is also caused by the acid washing caused by the "oxide skin pressing in" during the hot rolling process of the substrate. The oxide skin is washed away by the acid solution, and the remaining bulge forms the iron chip.

In order to prevent the formation of particles on the surface of hot dip galvanizing steel products, the first is: at the outlet of continuous casting billet or plate heating furnace, the oxide skin formed on the surface of slab should be thoroughly cleaned, otherwise the surface quality problem will be caused in the subsequent process. Second: the surface scale should be completely removed during the roughing process, and the quality should be strictly controlled. The temperature of the slab during the roughing process is too high, and it is easy to form the oxide skin between the steps.