Functional Characteristics Of Cold Rolled Steel Coil

Cold-rolled steel coil is a kind of cold-rolled steel plate, commonly known as rolled hard coil. Due to the cold work hardening caused by continuous cold deformation, the strength and hardness of the rolled hard coil increase, and the toughness and plasticity index decrease, so the stamping performance will deteriorate, and it can only be used for simple deformed parts.
Cold-rolled steel sheets are processed from hot-rolled steel sheets at room temperature. Although the temperature of the steel plate will increase during processing, it is still called cold rolling. Due to the cold rolling of hot rolling after continuous cold deformation, the mechanical properties are poor and the hardness is too high. It must be annealed to restore its mechanical properties, and those that are not annealed are called cold rolled coils. Hard coils are generally used to make products that do not bend or stretch.
Generally, the boards are originally coiled materials, but they are cut twice according to different requirements of customers to make fixed-length materials. That is steel. However, some materials that are not suitable for cold rolling and re-rolling due to special reasons such as high strength can only be made into steel plates.
The difference between hot-rolled and cold-rolled steel sheets can be attributed to the following points:
1. There is no oxide skin on the surface of the cold plate, and the quality is good, while there is oxide skin on the surface of the hot plate, resulting in a low thickness difference;
2. The toughness and surface finish of the hot-rolled sheet are poor, and the price is low, while the ductility and toughness of the cold-rolled steel coil are good, but the price is high;
3. Rolling is divided into cold rolling and hot rolling, with recrystallization temperature as the distinguishing point;
4. Cold rolling: Cold rolling is generally used to produce strips, and its rolling speed is relatively high. Hot rolling: the hot rolling temperature is in phase with the forging temperature;
5. The surface of the unplated hot-rolled steel sheet is dark brown, and the surface of the unplated cold-rolled steel coil is gray. After electroplating, it can be distinguished from the smoothness of the surface, and the smoothness of cold-rolled steel coils is higher than that of hot-rolled sheets.
Cold rolled steel coil is a steel coil that further thins the steel plate at room temperature to a target thickness below the recrystallization temperature. Compared with hot-rolled steel sheets, cold-rolled steel coils have more precise thickness, smooth and beautiful surfaces. Usually cold rolled steel coils are produced without heating before rolling. However, due to the small thickness of the strip, it is prone to shape problems, and the finished product can be obtained after cold rolling. Therefore, in order to control the dimensional accuracy and surface quality of the strip, many tedious processes are used. With the improvement of users' requirements for strip dimensional accuracy, shape and surface quality, cold rolling mills have more control models, l1 and l2 systems and shape control means than hot rolling mills, and the temperature of rolls and strips is also more important One of the control indicators. By definition, steel ingots or billets are difficult to deform and process at room temperature, and most steel products are rolled by hot rolling.
However, at high temperature, oxide scales are easily formed on the surface of the steel, which makes the surface of the hot-rolled steel rough and the size fluctuates greatly. Therefore, it is required to use hot-rolled semi-finished products or finished products as raw materials, and then perform cold rolling to produce steel with smooth surface, accurate size and good mechanical properties.
Because the cold-rolled steel coil is obtained from the hot plate after the hot rolling process, some surface processing will be carried out during the cold rolling, so the surface quality (such as surface roughness) of the cold plate is better than that of the hot plate. Therefore, if the later orders have higher requirements on the coating quality of products such as coating, cold plates are generally used, and the other hot plates are divided into pickled plates and non-pickled plates. The surface of the pickled plate becomes Normal metallic color. But the surface is not as high as the cold plate, because it is not cold-rolled, and the surface of the plate without pickling usually has a layer of black hair oxide layer, or a layer of black ferric oxide. Generally speaking, it looks like it has been burned. If the storage environment is not good, it will usually be embroidered.
Since the properties of cold rolled coil and hot plate are not much different, the influencing factor of formability depends on the difference in surface quality. Because the surface quality is better than that of the hot plate, it is said that the forming appearance of the cold plate is better than that of the hot plate.