Let’s understand the principle and process of hot galvanizing of steel grating


Hot dip galvanizing of steel grating, also known as hot dip galvanizing, is to melt zinc ingot at high temperature, put some auxiliary materials into it, and then immerse the steel grating member into the galvanizing tank to attach a layer of zinc layer to the steel grating member. The advantage of hot-dip galvanizing is its strong anti-rust ability, and the adhesion and hardness of the galvanized layer are better. The weight of steel grating products increases after galvanizing, which is often referred to as the amount of zinc.

The formation process of hot-dip galvanized zinc layer is the process of forming iron-zinc alloy between the iron substrate and the pure zinc layer outside. The iron-zinc alloy layer is formed on the surface of the workpiece during hot-dip plating, which makes the iron and pure zinc layer Good combination. When the iron workpiece is immersed in molten zinc liquid, a solid melt of zinc and α iron (body core) is first formed at the interface. This is a crystal formed by dissolving zinc atoms in the solid state of the matrix metal iron. The two metal atoms are fused, and the attraction between the atoms is relatively small.5

Therefore, when zinc reaches saturation in the solid melt, the atoms of the two elements of zinc and iron diffuse into each other, and the zinc atoms that diffuse into the iron matrix migrate in the matrix lattice, gradually forming an alloy with iron, and diffusing to The iron in the molten zinc liquid forms the intermetallic compound FeZn13 with zinc, which sinks into the bottom of the hot-dip galvanized pot, which is zinc slag. When the workpiece is removed from the zinc immersion liquid, a pure zinc layer is formed on the surface, which is a hexagonal crystal.

Different temperatures and different holding times, the amount of iron dissolved, that is, the amount of iron loss, is different. At around 500 ℃, the amount of iron loss increases sharply with heating and holding time. Below or above the range of 480~510 ℃, the iron loss increases slowly with time. Therefore, people call 480~510 ℃ as malignant dissolution zone. In this temperature range, zinc liquid corrodes the workpiece and zinc pot seriously, and the iron loss increases significantly over 560 ℃. Zinc over 660 ℃ corrodes the iron matrix destructively. Zinc slag will increase sharply and plating cannot be carried out.

Post time: Jul-12-2022