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What Is Difference Between Hot Rolled Steel And Cold Rolled Steel?
What is hot rolled steel Hot-rolled steel is a steel that has been heated and rolled at a high temperature. Its strength is not very high, but it is sufficient for our use. Its plasticity and weldability are good, so we use it more often; cold-rolled steel is ordinary hot rolling. Steel is strongly drawn beyond the strain hardening stage of the steel, its strength is high, but the toughness, weldability is poor, relatively hard and brittle!
What is hot rolling
Hot rolling is the heating of the material during the rolling process or before rolling. Rolling is generally carried out after heating to a temperature above the recrystallization temperature. Such as: 1000 degrees or more, hot rolling is processed at high temperatures. Allow the interior of the steel to recrystallize. Let it be more excellent. However, hot rolling does not change the structural properties of the metal.
What is cold rolled steel Cold rolled steel is steel that has been produced by cold rolling. Cold rolling is a steel sheet in which the No. 1 steel sheet is further rolled to a target thickness at room temperature. Compared with hot-rolled steel sheets, cold-rolled steel sheets are more precise in thickness and have a smooth and beautiful surface, as well as various superior mechanical properties, especially in terms of processability. Because cold-rolled raw rolls are brittle and hard, they are not suitable for processing. Therefore, cold-rolled steel sheets usually need to be given to customers after annealing, pickling and surface smoothing. The maximum thickness of cold rolling is 0.1–8.0MM or less. For example, the thickness of cold-rolled steel sheets in most factories is 4.5mm or less; the minimum thickness and width are determined according to the equipment capacity and market demand of each factory.
The difference between cold rolled steel and hot rolled steel
The difference between cold rolled steel and hot rolled steel is not in the smelting process, but in the temperature of the rolled steel, or the rolling end temperature. When the finish rolling temperature is lower than the recrystallization temperature of the steel, it becomes cold rolled steel. Hot rolled steel is easier to roll than cold rolled steel and is more efficient. However, after the steel under hot rolling conditions is oxidized, the surface color is dark and gray. Cold rolled steel has a higher power requirement for the rolling mill, and the rolling efficiency is lower, and in order to eliminate the work hardening, annealing is required during the rolling process. This greatly increases the processing cost, but the surface of such cold-rolled steel is bright and of good quality. It can be used directly to process finished products and is widely used.