What is the difference between hot-rolled and cold-rolled galvanized steel sheets

In the conventional trade of galvanized steel sheets, cold-rolled galvanizing is the predominant method, while hot-rolled galvanized steel sheets are relatively uncommon. So, what are the differences between hot-rolled and cold-rolled galvanized steel sheets? Let's briefly explain the differences in the following aspects:

1. Processing Cost of Galvanized Steel Sheets

Because hot-rolled steel sheets require one less process, the production cost of galvanizing hot-rolled steel sheets is lower than that of cold-rolled steel sheets. This is primarily due to the annealing and cold-rolling costs, with other processes similar between the two.

2. Quality and Performance of Galvanized Steel Sheets

Because hot-rolled steel sheets undergo only pickling and annealing to remove surface impurities, their surface is relatively rough, resulting in better zinc adhesion and a coating thickness of approximately 140/140 g/m². However, the thickness is not as precise as cold-rolled steel sheets, and since the zinc layer is often thick, the control of the zinc layer thickness is also uneven. Mechanical properties are similar, and some properties are even better than those of cold-rolled steel sheets.

3. Applications of Galvanized Steel Sheet

Hot-rolled galvanized steel sheet lacks the dimensional accuracy and surface quality of cold-rolled steel sheet, and is thicker than cold-rolled galvanized steel sheet. Therefore, it is often used in structural components where surface requirements are low but strength and thickness are high. Examples include structural components for home appliances such as washing machines and refrigerators, automotive interior components, chassis components, bus bodies and roofs, highway guardrails, and cold-formed steel. Because hot-rolled galvanized steel sheet is less expensive and, with technological advancements, is becoming increasingly thicker, its use is also steadily increasing.

4. Galvanized Steel Sheet Grades

Common hot-rolled galvanized steel sheet grades include DD51D+Z, HD340LAD+Z, HR340LA, HR420LA, and HR550LA.

Cold-rolled galvanized steel sheet grades include DC51D+Z, HC340LAD+Z, HC340LA, HC420LA, and HC550LA.

Some grades, such as DX51D+Z, do not specify whether the base material is hot-rolled or cold-rolled. These grades are generally considered hot-rolled galvanized steel sheets.