The demand for high-quality special steel used in fastener production in my country will continue to rise

With the continuous advancement of the process of revitalizing the equipment manufacturing industry in my country, the speed of industrial upgrading is accelerating, and the demand for fasteners is increasing, which also increases the demand for high-quality special steel used in fasteners.

　　 According to rough statistics, there are more than 40,000 varieties and millions of fasteners in various forms and specifications at home and abroad, which are mainly used in the automobile industry, machinery manufacturing, electronics industry, construction and maintenance industries, etc. Among them, the automobile industry is the largest user, whose demand accounts for about 23.2% of the total sales of fasteners; followed by the maintenance industry market and the construction industry, whose demand accounts for about 20% of the total sales of fasteners; and the third is electronics. Industry, its demand accounted for about 16.6% of the total sales of fasteners. Industry insiders predict that in 2013 and throughout the 12th Five-Year Plan period, the potential market for special steel for fasteners is very large. It is estimated that in 2013, my country's fastener production and sales will reach 7.2 million to 7.5 million tons; by 2015, the market size of my country's fastener industry will be close to 200 billion yuan. Therefore, the demand for high-quality special steel used in fastener production will continue to show an upward trend.

　　 Industry insiders believe that benefiting from the rapid development of industries such as automobiles, wind power, construction, manufacturing, high-end equipment, new energy, etc., in the medium and long term, the demand for fasteners in my country will continue to grow rapidly.

　　The country attaches great importance to the research and development of fasteners in some industries. On November 12, 2012, the National Development and Reform Commission and the Ministry of Industry and Information Fasteners and other 7 projects are listed as special technical reform projects in 2013, including high-speed train gear transmission, energy-saving and environmentally friendly automatic transmission and key components, large-scale marine gear transmission, automobile engine and automatic transmission chain, and automobile engine fasteners , Automobile suspension springs, automobile high-strength powder metallurgy parts, etc.

　　The steel used in the fastener manufacturing industry is mainly cold-headed steel wire rod, the grades are 22A, 35K, etc., and the specifications range from 6.5mm to 20mm. This cold-headed steel wire rod is mainly used to manufacture bolts, nuts, and rivets. , Bolts, etc. Due to the different operating temperatures of the fasteners, the materials used are also different. When the working temperature is below 370℃, tempered medium carbon steel is generally used; for temperature above 370℃, heat-resistant steel is mostly used; below 480℃, chromium-molybdenum low-alloy pearlitic heat-resistant steel is used; below 540℃, chromium-molybdenum is used Vanadium low-alloy pearlitic heat-resistant steel; below 570℃, high-chromium martensitic heat-resistant steel is used, but the linear expansion coefficient of this steel is small, and the pre-tightening force cannot be too large in the cold state to prevent it from reaching the working temperature When the fastener is overloaded and yielded.

　　 In recent years, my country's steel industry has increased the research and development of steel for fasteners. At present, nearly 40 iron and steel enterprises, including Baosteel, Xianggang, Baotou Steel, Shougang, etc., are producing cold heading steel, and some steel grades have approached or reached advanced foreign levels. There are also a number of steel mills that have established cooperative relations with the fastener industry, forming an industry group of wire rods for cold heading in my country. The product varieties include low-carbon, ultra-low-carbon, medium-carbon (quenched and tempered), low-alloy steel and surface carburizing hardened steel, with specifications ranging from 5.5mm to 42mm, covering almost all of the fastener steel demand. Although the development of domestic cold-heading steel wire rod and wire rod started late, it has developed rapidly, especially since the mid-1980s, high-speed wire rod production lines and wire rod continuous rolling production lines have been put into production. The production of strips provides a guarantee on equipment.

　　 With the development of my country's fastener manufacturing industry to produce high-end products, higher requirements are put forward for fastener steel. Such as petrochemical equipment fasteners, which are mainly used for high-pressure vessels, various cylinders, tanks and other equipment. They are characterized by contact with acid, alkali, salt and other corrosive media, and they have to withstand the test of various harsh environments. The steel for high temperature fasteners is required to have a sufficiently high yield limit, a high relaxation stability, a sufficiently high lasting plasticity, and an oxidation resistance. In order to ensure the sealing of the high-temperature container, a certain pre-tightening force must be given to tighten the bolts and nuts. According to the operating experience of thermal power plants, the pre-tightening stress is generally specified to be 250MPa~350MPa. The durable plasticity of bolt steel after long-term operation at high temperature should be less than 3% to 5% to slow down the brittle fracture of bolt steel.

　　 Industry insiders believe that the development and production of steel for fasteners in my country started late and cannot fully meet the current domestic fastener production needs, nor can it meet the needs of exports. In addition, the production and market circulation of cold heading steel in my country also borrow a large number of grades such as G3506, G3507, G4105 in the JIS standard and many steel grades in the American ASTM standard.

　　 Industry insiders suggest that according to the fastener industry’s requirements for fastener steel, iron and steel companies should increase their efforts in the research and development of cold-heading steel, and develop high-strength, high-heat-resistance, and high-formability cold-heading steel. Meet the increasingly stringent mechanical performance requirements of fasteners.