How to distinguish between cold formed steel and hot rolled steel?

First, the nature is different.

1. Cold-formed steel: It is a section steel of various cross-sectional shapes and sizes made by bending and forming hot-rolled or cold-rolled strip steel.

2. Hot-rolled section steel: It is a steel with various geometric cross-sectional shapes rolled by heating billet.

Second, the process is different.

1. Cold-formed steel: Cold-formed steel is the main material for making light steel structures, which is made of steel plate or steel strip cold-formed forming. Its wall thickness can not only be made very thin, but also greatly simplify the production process and improve production efficiency.

It is possible to produce a variety of profiles and cold-formed sections of different materials with uniform wall thickness but complex cross-sectional shapes that are difficult to produce by general hot rolling methods.

2. Hot-rolled steel: low-alloy steel hot-rolled steel is mostly hot-rolled rebar and 16mn rolled steel, and special-shaped section steel is used less. Compared with ordinary I-beam, H-beam has the advantages of large cross-sectional modulus, light weight, steel saving, and easy combination and connection with other components.

Third, the use is different.

1. Cold-formed steel: its use can be roughly divided into 10 categories: highway guardrail plates, steel structures, automobiles, containers, steel formwork and scaffolding, railway vehicles, ships and bridges, steel sheet piles, transmission towers, and others.

2. Hot-rolled section steel: In China, according to the size of the section size of the section of the section, hot-rolled section steel has become one of the most widely used materials in various capital construction, such as threaded steel bars, axles and ploughshare steel. Machinery, chemical, shipbuilding, mining, petroleum and railway departments all use a large number of various types of hot-rolled section steel.

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 reasons for the residual stress of 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.

Cold-formed steel equipment has a very high competitiveness both at home and abroad. The traditional cross-sectional steel is made by hot or cold rolling, and the drawing and pressure forming are carried out at room temperature to produce various cross-sectional steels. However, with the advent of cold-formed steel equipment, electric current and infrared rays have been used at home and abroad to preheat the steel plate, and then carry out the forming work.

The difference between cold-formed steel equipment and traditional methods is that it does not need to be carried out at room temperature, but uses heating and bending. Maybe everyone thinks that the application of cold-formed steel equipment is relatively simple, but because they ignore some details, there are many problems, such as the wrong way to start, let's take a look at how to start cold-formed steel equipment.

Before you open the cold-formed steel equipment, you must place the equipment in a stable position, and you can't shake it artificially, and then open the legs of the chassis, which is beneficial for everyone to observe. Then connect the power supply, and the power supply of the general cold-formed steel equipment is a three-limit power supply.

Next, we should turn on the total power supply of the case, and then adjust the value, if the indicator light is on, then we can go to the next operation. Then the sealing of the cold-formed steel equipment is inspected, and the operation is carried out for different materials, so as to ensure the quality of the section steel. It is also important to pay attention to the condition of the deviation of the lower cold-formed steel equipment, because the contraction of the terminal supporting it is very inflated, which can only indicate a small part under normal circumstances.

Cold-formed sections have unique characteristics and have specifications that cannot be completed by hot-rolled sections. [Vision Network].

Definition: Cold-formed steel, also known as steel refrigerated bent profile or cold-formed profile, refers to a variety of cross-sectional shapes and sizes made of hot-rolled or cold-rolled strip steel as a billet through bending and forming, is an economical cross-section light-walled thin-walled steel, cold-formed steel is the main material for making lightweight steel structures. It has a variety of extra-thin, reasonably shaped and complex cross-sections that cannot be produced by hot rolling.

Compared with hot-rolled section steel, under the same cross-sectional area, the radius of rotation can be increased by 50% to 60%, and the moment of inertia of the cross-section can be increased to many times, so the strength of the material can be used more reasonably; Compared with ordinary steel structure, it can save about 30% to 50% of steel. In some cases, the amount of steel used in the cold-formed steel structure is equivalent to the amount of steel used in the reinforced concrete structure under the same conditions, which is an economic section steel.

Classification: According to the different smelting quality of steel, cold-formed steel is divided into ordinary cold-formed steel and high-quality cold-formed steel. Ordinary cold-formed steel is divided into large steel, medium steel and small steel according to the current metal product catalog.

According to its cross-sectional shape, ordinary steel sock grip can be divided into I-beam, channel steel, angle steel, round steel, etc.

Large-scale cold-formed good loose steel: large section steel in I-beam, channel steel, angle steel, flat steel are hot-rolled, round steel, square steel, hexagonal steel in addition to hot rolling, forging, cold drawing, etc. I-beams, channel steels, and angle steels are widely used in industrial buildings and metal structures, such as workshops, bridges, ships, agricultural machinery and vehicle manufacturing, transmission towers, and transportation machinery, which are often used together.

Flat steel is used in construction sites as bridges, house trusses, fences, power transmission ships, vehicles, etc. Round bars and square bars are used as various mechanical parts, agricultural machinery accessories, tools, etc.

Medium-sized cold-formed steel: medium-sized cold-formed steel is medium-working, grooved, angled, round, and flat, and its use is similar to that of large-scale cold-formed steel.

Small cold-formed steel: small cold-formed steel medium angle, round, square, flat steel, processing and use are similar to large cold-formed steel, small diameter round steel is often used as construction steel.

1. The production method is different: hot-rolled steel is rolled in the heated state of steel; Cold-rolled steel is rolled at room temperature. 2. Different applications:

Hot-rolled steel is mostly used in construction, rails, and frames; Cold-rolled steel is mostly used in household appliances and metal containers. 3. The appearance is different: the 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.

Data development. Hot-rolled steel is a steel rolled by high temperature heating, its strength is not very high, but enough to meet our use, its plasticity, weldability is good, so the public is more commonly used; Cold-rolled steel is a steel that ordinary hot-rolled steel has been strongly drawn to exceed the strain hard residual state vertical stage, its strength is very high, but the toughness and weldability are poor, and it is relatively hard and brittle. Hot rolling is processed at high temperatures.

Hot rolling is the need to heat the material during or before the rolling process. Generally, it is heated above the recrystallization temperature before rolling.

Continuous hot-dip of hot-rolled steel strip is a new process for the production of hot-dip galvanized sheet, the application of this process greatly improves the efficiency of steel strip production, and is of great significance for ensuring the quality of steel strip. The production of continuous hot-dip galvanizing of hot-rolled steel strip was produced in Japan in the 70s, the technology is an important innovation to improve the production technology of steel strip, in the context of people's higher and higher requirements for the quality of hot-dip galvanized sheet, strengthening the research of continuous hot-dip galvanizing technology of hot-rolled steel strip has become the inevitable choice of iron and steel enterprises.

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, and the surface is vertical, smooth and beautiful, and it 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.

1. Appearance and surface quality: Because the cold plate is obtained by the hot plate after cold rolling, and some surface finishing will be carried out by cold rolling, the surface quality of the cold plate is relatively good. For products with high coating quality requirements, such as subsequent painting, cold plates are usually chosen.

Uncut plates usually have a layer of oxide on the surface, black, or a layer of ferric tetroxide. In layman's terms, it's like brown, and if the storage environment is not good, it usually rusts.

2. Performance: Under normal circumstances, the mechanical properties of the hot plate and the cold plate are considered to be the same in the project. Although cold plate has a certain degree of hardening during the cold rolling process, the elastic limit of cold plate is usually slightly higher than depending on the degree of annealing of the cold plate, and its surface hardness is also higher.

However, the strength of annealed cold plates is higher than that of hot plates.

3. Forming performance: Since there is basically no difference between the performance of the hot plate and the cold plate, the factors affecting the formability depend on the surface quality. However, since the surface quality is better than that of the cold plate, the steel plate of the same material is usually used, and the forming effect of the cold plate is better than that of the hot plate.

Cold rolled steel and hot rolled steel refer to steel manufactured under different process conditions, and there are the following differences between them:

1.Production process: cold-rolled steel is processed and pressed at room temperature, while hot-rolled steel is processed and pressed at high temperature. Specific process parameters and operating procedures also vary.

2.Material properties: Due to different processes, the physical properties and mechanical properties of cold-rolled steel and hot-rolled steel are different.

Cold-rolled steel has high strength and hardness, good corrosion resistance, but relatively low plasticity. Hot-rolled steel undergoes high temperature treatment during processing, and has good plasticity and toughness.

3.Surface quality: The surface of cold-rolled steel is usually smooth, flat, has good dimensional accuracy, and is usually free of oxide scale or rust. There may be some oxide scale, rust or flakes on the surface of hot-rolled steel.

4.Size control: Due to the characteristics of the cold-rolled process, the dimensional accuracy of cold-rolled steel is relatively high, the length is more stable, and the diameter and wall thickness are better controlled. Hot-rolled steel, on the other hand, undergoes a large deformation at high temperatures, with relatively low dimensional accuracy, and there may be certain deviations.

5.Application fields: cold-rolled steel is mostly used in fields that require high dimensional accuracy, strength and hardness, such as automobile reputation and simple car manufacturing and machinery.