What does the conversion ratio of hot and cold rolling of steel mean

The meaning of the conversion ratio of cold and hot rolling of steel:

The hot-rolled products are further processed into cold-rolled products, and the conversion rate of this product is called the conversion ratio of cold and hot rolling, which is used to measure the processing capacity and comprehensive strength of iron and steel enterprises.

Cold rolling: hot rolled steel coil as raw material, cold continuous rolling after 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 the rolled hard coil rise, and the toughness and plastic index decrease, so the stamping performance will deteriorate, and it can only be used for simple deformation of parts.

Hot rolling: It is relative to cold rolling, which is the rolling that is carried out below the recrystallization temperature, while hot rolling is the rolling that is carried out above the recrystallization temperature.

Only after processing can the comprehensive properties of steel be greatly improved. Therefore, the primary steel obtained from smelting needs to be processed by pressure to become steel. According to the processing temperature, pressure processing is mainly divided into hot pressure processing (above the recrystallization temperature) and cold pressure processing (below the recrystallization temperature), hot rolling, hot extrusion, hot perforation, etc., which is hot pressure processing, cold rolling, cold drawing, cold stamping, cold extrusion, etc.

For steel, it is mainly hot and cold rolled. Hot rolling is generally used as the primary processing and production technology of steel, which is easy to form, rough in appearance, and poor in size and surface quality, so the added value is low; Cold rolling is generally used as a deep processing production process of steel, such as mirror panels, thin plates, decorative steel, automobile plates, etc., with accurate surface size, high surface quality, high yield and high added value of products, so the current iron and steel complex in order to improve the output value and economic benefits, increase the output of end products, most of the hot rolled products are further processed into cold rolled products. The conversion rate of this product is called the conversion ratio of hot and cold rolling.

It is used to measure the processing capacity and comprehensive strength of iron and steel enterprises.

It's the intensity conversion ratio.

Summary. Performance: In general, the mechanical properties of the hot plate and the cold plate in the project are considered to be indistinguishable, although the cold plate has a certain work hardening in the cold rolling process, (but it is not excluded that the mechanical properties are strict, then it needs to be treated differently), the cold plate is usually slightly higher than the yield strength of the hot plate, and the surface hardness is also higher, how to see the degree of annealing of the cold plate.

But no matter what, the strength of annealed cold plate is higher than that of hot plate.

What is the difference between hot rolling and cold rolling of steel, in terms of price and practicality, thank you.

Performance: In general, the mechanical properties of the hot plate and the cold plate in the project are considered to be indistinguishable, although the cold plate has a certain work hardening in the cold rolling process, (but it is not excluded that the mechanical properties are strict, then it needs to be treated differently), the cold plate is usually slightly higher than the yield strength of the hot plate, and the surface hardness is also higher, how to see the degree of annealing of the cold plate. But no matter what, the strength of annealed cold plate is higher than that of hot plate.

Generally speaking, cold-rolled products are more expensive than hot-rolled, of course, the performance is good, because cold-rolled products have higher dimensional accuracy, surface quality and process performance.

The main differences between hot rolled and cold rolled are:

1. Appearance and surface quality

Because the cold plate is obtained by the hot plate after the cold rolling process, and the cold rolling will also carry out some surface finishing, the cold plate is better than the hot plate in terms of surface quality (such as surface roughness, etc.), so if there are higher requirements for the coating quality of the product such as post-painting, the cold plate is generally selected.

In addition, the hot plate is divided into pickled plate and non-pickled plate, the surface of the pickled plate is normal metal color due to pickling, but the surface is not cold-rolled so the surface is still not as high as the cold plate, and the surface of the non-pickled plate usually has an oxide layer, black, or there is an iron tetroxide black layer. In layman's terms, it is as if it has been roasted by fire, and if it is stored in a bad environment, it will usually have a little rust.

2. Performance: Under normal circumstances, the mechanical properties of the hot plate and the cold plate in the project are considered to be indistinguishable, although the cold plate has a certain work hardening in the cold rolling process, (but it is not excluded that the mechanical properties are strict, then it needs to be treated differently), the yield strength of the cold plate is usually slightly higher than that of the hot plate, and the surface hardness is also higher, and the specific how to see the degree of annealing of the cold plate. But no matter what, the strength of annealed cold plate is higher than that of hot plate.

3. Forming performance: because the performance of the cold and hot plates is basically not too much, the influencing factors of the forming performance depend on the difference in their surface quality, because the surface quality is better than that of the cold plate, so generally speaking, the steel plate of the same material, the forming effect of the cold plate is better than that of the hot plate.

Hot-rolled steel is a steel rolled by high temperature heating, its strength is not very high, but it is enough to meet our use, its plasticity, weldability is good, so we are more commonly used; Cold-rolled steel is a steel that has been strongly drawn to exceed the strain hardening stage of ordinary hot-rolled steel, and its strength is very high, but the toughness and weldability are poor, and it is relatively hard and brittle!

Cold-rolled steel is steel that is produced by cold rolling. Cold rolling is the process of further thinning the steel plate to the target thickness at room temperature. Compared with hot-rolled steel plate, cold-rolled steel plate has a more accurate thickness, smooth and beautiful surface, and also has a variety of superior mechanical properties, especially in terms of processing performance.

Because the cold-rolled original coil is relatively brittle and hard, it is not suitable for processing, so under normal circumstances, the cold-rolled steel plate is required to be annealed, pickled and surface-smoothed before being handed over to the customer. The maximum thickness of cold-rolled steel is below, such as the thickness of cold-rolled steel plate in most factories is below; The minimum thickness and width are determined according to the equipment capacity and market demand of each plant.

In modernization, the steel binding technology is divided into two types: cold rolling and hot rolling, so what is the difference between these two technologies? Let's take a look.

Hot rolling is made of slabs (mainly continuous casting billets) as raw materials, and after heating, strip steel is made from roughing mills and finishing mills.

Cold rolling, with hot-rolled steel coil as raw material, after pickling to remove the oxide scale, the finished product is rolled hard coil, due to the continuous cold deformation caused by cold work hardening so that the strength of the rolled hard coil, hardness rises, toughness and plastic index decreases, so the stamping performance will deteriorate, only Mingyan Huineng can be used for simple deformation of parts.

Difference Between Cold Rolled and Hot Rolled:

1. Processing technology

In terms of processing technology, hot rolling is hot working, and cold rolling is cold working. Hot rolling is rolling above the crystallization temperature, and cold rolling is rolling below the crystallization temperature.

2. Scope of application

Hot rolling is mainly used for the production of steel structural parts, jujube bridges, ships, vehicles, and various mechanical parts, etc., and cold rolling is mainly used for home appliances such as automobiles, refrigerators, washing machines, as well as industrial equipment and various building materials.

3. Appearance performance

1) Cold-rolled forming steel allows local buckling of the cross-section, so that the bearing capacity of the member after buckling can be fully utilized; Hot-rolled sections, on the other hand, do not allow local buckling of the cross-section.

2) The causes of residual stress in hot-rolled steel and cold-rolled steel are different, so the distribution on the cross-section is also very different. The residual stress distribution on the cross-section of cold-formed thin-walled steel is curved, while the residual stress distribution on the cross-section of hot-drawn or welded steel is thin-film.

3) The free torsional stiffness of hot-rolled steel is higher than that of cold-rolled steel, so the torsional resistance of hot-rolled steel is better than that of cold-rolled steel.

Hello: The main difference between cold rolling and hot rolling is whether the rolling temperature is above the recrystallization temperature.

The so-called hot rolling is to roll above the metal recrystallization temperature, and the recrystallization of grains will occur at the same time during the deformation process of the metal to obtain a finer economic structure. At the same time, the deformation resistance of the metal will be lower than that of cold rolling, and greater deformation rolling can be achieved.

The so-called cold rolling is rolled below the metal recrystallization temperature, and the metal deformation process is mainly composed of the slip of the metal and the plugging of dislocations. Due to the blockage of dislocations, the yield limit of the metal increases, but the plasticity decreases relatively. This is also known as work hardening.

The surface of cold-rolled steel is high, the product size is fine, the thickness is uniform, and the plate shape is straight; Thin strips that cannot be produced by the hot rolling method can be obtained; The disadvantage is that in the cold rolling process, there is a large internal stress inside the material, so it is easy to twist and deform in the processing process.

The hot-rolled steel products have good comprehensive properties and good deep drawing properties; But the surface quality is not as good as cold-rolled steel.