Cold rolling and hot rolling

It’s hard to say; it depends on where it’s used and under what conditions, as their uses vary. Hot-rolled steel sheets have mechanical properties that are far inferior to those of cold-processed steel, and they are also less good than those of forged steel; however, they possess better toughness and ductility. Cold-rolled steel sheets, due to a certain degree of work hardening, have low toughness, but they can achieve a good yield strength ratio, making them suitable for use in parts such as cold-formed spring plates. Additionally, since the yield point is close to the tensile strength, there is little predictability regarding potential hazards during use, and accidents can occur easily when the load exceeds the allowable limit. 1) Cold-rolled sheets, having been processed through cold rolling, have no oxide scale on their surface and thus offer superior quality. The hot plates are produced by hot rolling, have an oxide scale on their surface, and exhibit variations in thickness. 2) Hot-rolled sheets have poor toughness and surface smoothness, and are cheaper; whereas cold-rolled sheets exhibit good ductility and toughness, but are more expensive. 3) Rolling is divided into cold rolling and hot rolling, with the recrystallization temperature serving as the dividing point. 4) Cold rolling: It is generally used for producing strips, and operates at higher rolling speeds. Hot rolling: The temperature used in hot rolling is similar to that used in forging. 5) Unplated hot-rolled sheets have a black-brown surface, while unplated cold-rolled sheets have a gray surface. After plating, the difference can be identified by the level of surface smoothness – cold-rolled sheets are smoother than hot-rolled sheets.