What’s the Difference between Hot-dip and Cold Galvanizing?

The destructive effects of corrosion on metals have been known for centuries. For almost as long as metals have been a construction material, humans have constantly been seeking ways to improve its longevity in corrosive environments. One of the most widely used techniques for protecting metals (mainly steel) is galvanizing.

There are two main methods of galvanizing : hot-dip galvanizing and cold-dip galvanizing.

Galvanizing, also known as hot-dip galvanized, it is the ingot melted at high temperatures, a number of supplementary material in place, then dipped galvanized metal structure slot, the metal component on a layer of zinc coating.The advantages of hot-dip galvanizing corrosion of his ability, adhesion and hardness of zinc coating is better.

“Cold plated” or “plating”, namely, the zinc salt solution by electrolysis, to the plating on the coating, generally do not have heating, small amount of zinc, the wet environment is very easy to fall off.

The difference between hot-dip galvanizing and cold-dip galvanizing:

• In hot-dip galvanizing, the raw material surface is a layer of intermetallic compounds, followed by zinc. However, the cold-dip galvanizing surface is zinc, there is no intermediate layer.

• The cold-dip galvanizing layer is thinner and the hot-dip galvanized layer thicker.

• Cold-dip galvanizing can not be produced in large quantities, and the output is low. Hot-dip galvanizing can be produced in large quantities with high output.

• Surface state and corrosion resistance of cold-dip galvanizing are better than that of hot dipping galvanizing.

• The anti-corrosion principle of cold galvanizing is the same as that of hot galvanizing. It's just that the two processes are different. 

• After cold galvanizing, the surface is smooth. The appearance is bright. But because the zinc layer is adhering, it will fall off after a long time.

• Hot-dip galvanizing------ part is less beautiful than cold galvanizing. However, the zinc layer has penetration, and the service time is longer than that of cold galvanizing.

• Chemical industry is generally galvanized more, suitable for small parts; hot-dip galvanized sheet is generally used for power equipment and components, suitable for large parts and equipment.