Knowledge of cold bending section steel

Cold formed steel refers to the finished steel with various cross-section shapes bent by steel plate or strip in cold state. Cold formed section steel is a kind of economic light-weight thin-walled steel, also known as steel cold-formed sections or cold-formed sections.

Cold formed section steel is the main material for making light steel structure. It has all kinds of very thin, reasonable and complex cross section which can not be produced by hot rolling. Compared with hot-rolled section steel, under the same section area, the turning radius can be increased by 50-60%, the section moment of inertia can be increased by 0.5-3.0 times, so the material strength can be reasonably utilized; compared with ordinary steel structure (i.e. the steel structure made of traditional I-beam, channel steel, angle steel and steel plate), the steel can be saved by about 30-50%.

The production of cold-formed steel in China started in the 1950s-1960s. The manufacturers are concentrated in Anshan, Shanghai, Chongqing and other regions, mainly serving the agricultural machinery industry. In the 1980s, it was the first high tide of development. The manufacturers expanded to East China, North China, northeast and other regions, and the service scope also expanded to trucks, buses, building doors and windows, highway guardrails, shelves, electrical appliances and other industries, but they were limited to small and medium-sized units, with a few varieties and specifications, about 2000 kinds; the materials were all plain carbon steel, and the output of all cold-formed steel accounted for about 1-1.5% of the total steel, which is in line with the world There is a big gap between countries in the world. In general, there are 8000-10000 kinds of cold-formed steel in foreign countries, with various materials, 50-70% of which are alloy steel, and 5% of which are cold-formed steel. Therefore, there is a great space for the development of cold-formed steel in China.

With the rapid development of China's iron and steel industry, especially the continuous improvement of plate strip ratio, it has reached 41.46%, which provides sufficient raw materials for the development of cold-formed section steel. The increase of plate strip quantity will inevitably promote the development of deep processing industry. In its application field, the advantages of cold-formed section steel are more and more recognized by users. It belongs to the economic section high-efficiency steel, which can save 15-30% metal, has less investment, flexible production, and can meet various requirements of users. It shows its unique advantages in the development of personalized market. It has become an irresistible trend that cold-formed section steel is widely used to replace hot-rolled sections and other varieties.

Up to now, there are more than 1000 cold-formed steel production lines in China, with a production capacity of 15 million tons per year. There are 50 sets of ф 200 - ф 660mm large-scale units newly built and under construction, which are mainly distributed in East China, North China and Northeast China. Cold formed steel is mainly used in highway construction, steel structure, automobile manufacturing, container, railway vehicle, steel formwork and scaffold, bridge, electrical cabinet, suspension conveyor, cable bridge, shelf, elevator guide rail, keel steel, vegetable shed, agricultural machinery, grain storage, furniture and fire protection equipment. According to the survey data of 9 industries conducted by Cold Formed Steel Association, the current demand is 4.3845 million tons / year, accounting for 2.4% of the total steel.

At present, the main varieties of cold-formed section steel in China are: cold-formed square rectangular tube for structure, cold-formed steel for passenger car, cold-formed steel for rolling shutter door and steel window, welded pipe for low-pressure fluid transmission, cold-formed section steel for general opening, cold-formed section steel for construction, and cold-formed different sections, which have been used in construction, machinery, nuclear power, automobile, railway, agricultural machinery, chemical industry, petroleum, refrigeration and food Goods, textile, medical, supermarket, container

Cold-formed steel is widely used in industry and civil industry, especially in the emerging industry. At present, there are few cold-formed sections made of stainless steel, galvanized steel, high-strength and ultra-high low alloy steel produced in China, which need to be imported; the cold-formed sections with cutting-edge development direction and the cold-formed sections with complex cross-section, ultra-thick, ultra-thin and series have a large potential market and a broad development prospect. At present, this kind of cold-formed steel is rare in China, many products are still blank, some can only be made up by imports. For example, the annual consumption of galvanized cold-formed steel used for luxury buses is at least 3000 tons. At present, imported products are mainly used, and the demand continues to rise.

The market of cold-formed steel in China has great potential and broad prospect, but the emphasis should be placed on the development of new-type cold-formed steel with high technology, high quality and high added value, the research of process technology in the field of cold-formed production, the development, development or introduction and digestion of new technical equipment, including the flexible cold-formed units with international cutting-edge technology level, etc., instead of rushing together to lower water level The repeated construction of peace.