What is cold rolled steel

The difference between cold rolled steel and hot rolled steel lies not in the smelting process, but in the rolling temperature, or the end temperature of rolling. If the final rolling temperature is lower than the recrystallization temperature of steel, it becomes cold rolled steel. Hot rolled steel is easy to roll and has high rolling efficiency, but under hot rolling conditions, the steel is oxidized and the product surface is black and gray. Cold rolled steel requires high mill power and low rolling efficiency, and intermediate annealing is also required to eliminate work hardening in the rolling process, so the cost is also high. However, cold rolled steel has bright surface and good quality, and can be directly used to process finished products. Therefore, cold rolled steel plate is widely used.

The hot-rolled steel coil is used as raw material for cold continuous rolling after acid pickling to remove the oxide scale. The finished product is rolled hard coil. Due to the cold work hardening caused by continuous cold deformation, the strength and hardness of rolled hard coil increase and the toughness and plasticity index decrease. Therefore, the stamping performance will deteriorate and can only be used for simple deformed parts. The hard rolled coil can be used as the raw material of the hot-dip galvanizing plant, because the hot-dip galvanizing units are equipped with annealing lines. The weight of rolled hard coil is generally 6 ~ 13.5 tons. The hot-rolled pickling coil is continuously rolled at room temperature. The inner diameter is 610mm.

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