What is the difference between hot rolled galvanized and cold rolled galvanized？

In the regular trading of galvanized sheets, cold-rolled basic galvanization is the main one, and hot-rolled substrates are relatively rare. Then, what is the difference between hot-rolled substrates and cold-rolled substrates galvanized products? Let’s make a simple interpretation from the following aspects

Cost

Because there is one less process than the cold-rolled substrate, the production cost of galvanizing the hot-rolled substrate is lower than that of the cold rolling, mainly due to the annealing cost and the cold rolling cost, and the other processes are similar.

Quality & Performance

Because the hot-rolled substrate is only pickled and annealed to remove surface impurities, its surface is relatively rough, the adhesion of the zinc layer is better, and the thickness of the coating is biased toward 140/140g/m2. However, the thickness dimension is not as high as that of cold rolling. Since most of them are thick zinc layers, the thickness of the zinc layer is not uniformly controlled. There is little difference in mechanical properties, and some properties are even better than cold rolling.

Application Field

Hot-rolled base plate galvanized sheet is not as good as cold-rolled base plate because of its dimensional accuracy and surface quality, and the thickness is thicker than cold-rolled galvanized sheet, so it is often used for structural members with low surface requirements but high strength and thickness requirements.

For example, the structural parts of washing machines, refrigerators and other household appliances, automobile internal structural parts, automobile chassis structural parts, passenger car body, roof, highway guardrail, cold-formed steel, etc.

Because the cost of hot-rolled galvanized sheet is low, and as the technology progresses, the thickness of the specifications is getting larger and larger, and the amount of use is gradually increasing.

Grade

Common grades of hot-rolled galvanized sheet are DD51D+Z, HD340LAD+Z, HR340LA, HR420LA, HR550LA, etc.;

The cold-rolled galvanized sheet corresponds to DC51D+Z, HC340LAD+Z, HC340LA, HC420LA, HC550LA, etc.;

There is also a grade that does not specify whether it is cold-rolled or hot-rolled substrate, such as DX51D+Z. Generally, this grade can be considered as hot-rolled galvanized sheet.