Manufacture and Processing of Cold Rolled Steel

Cold rolled steel is steel produced by cold rolling. Cold rolling is the further thinning of No.1 steel plate to the desired thickness at room temperature. Compared with hot-rolled steel plate, cold-rolled steel plate thickness is more accurate, and the surface is smooth and beautiful, but also has a variety of superior mechanical properties, especially in terms of processing properties. Because the cold-rolled coil is brittle and hard, it is not suitable for processing, so the cold-rolled steel plate is usually required to be annealed, pickling and surface smoothing before being handed to the customer. The maximum thickness of cold rolling is below 0.1-8.0mm, such as the thickness of most cold-rolled steel plates in factories is below 4.5MM; The minimum thickness and width are determined according to the equipment capacity and market demand of each plant.

Introduction

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

Processing method

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