The differentce between the cold-rolled steel and hot-rolled steel

- Sep 21, 2020-

1. Different brightness


The cold-rolled steel sheet is very bright, flat, good in appearance and standard in thickness. When it is not rusted, it looks a bit as bright as stainless steel; the hot-rolled surface is rough, and the shape has no cold-rolled rules, and it is also iron when it is not rusted. grey.


2. Different smoothness


The cold plate is cold rolled and the surface has no oxide skin and is of good quality. The hot plate is processed by hot rolling, and the surface has oxide skin, and the thickness of the plate is lower. After electroplating, it can be distinguished from the smoothness of the surface. The smoothness of cold rolled plates is higher than that of hot rolled plates.




3. Different materials


Cold-rolled sheets are made from hot-rolled coils, which are rolled at room temperature below the recrystallization temperature, including sheets and coils, which can be produced by many domestic steel plants such as Baosteel, Wuhan Iron and Steel, Anshan Iron and Steel, etc. Among them, the one delivered in pieces is called steel plate, also called box plate or flat plate; the one that is very long and delivered in coils is called steel strip, also called coil.


The hot plate uses continuous casting slab or blooming slab as raw material, heated by a walking heating furnace, high-pressure water descaling, and then enters the rough rolling mill. The rough rolling material is cut head, tail, and then enters the finishing mill for computer-controlled rolling. After finishing rolling, it undergoes laminar cooling (computer controlled cooling rate) and coiled by a coiler to become a straight hair coil.


4. Different specifications and thickness


Cold-rolled sheets are generally thin gauges with a thickness of less than 3.0mm. Silver-white is galvanized sheet, and color is color-coated sheet. The surface is absolutely oil-free. The whiter is cold-rolled sheet, which is very clean and flat, highly reflective, and is made of steel. Harder.


The hot-rolled sheet is generally 1.5mm or more, and the thinnest is not less than 1.0. If it is less than 0.8, it is definitely a cold-rolled sheet. The surface is iron gray, brown and earthy, with temperature-changing oxidation patterns, and the surface is rougher than cold-rolled (flattened Except) The surface process is obviously not as fine as the cold rolled plate.