Where can I use "special steel"?

Special steel is the most important steel used in most industries of national economy, such as machinery, automobile, military industry, chemical industry, household appliances, ships, transportation, railways and emerging industries. China Special Steel Industry undertakes special steel products needed by national defense and military industry, high-tech industry, machinery, automobile and other key industries. \x0d\ The world's major special steel producers are Japan, Germany, Sweden, the United States, France, Italy, Spain, South Korea and so on. , accounting for more than 90% of the global special steel export market. \x0d\ China's special steel industry was originally built to support national defense, military industry and aerospace, and its output has developed rapidly with the growth of automobile industry in recent ten years. In 20 10, the annual output of special steel was 34 million tons, accounting for about 5-20% of the world. \x0d\ At present, there are 32 major special steel enterprises (members of the Special Steel Association) in China, which undertake more than 60% of the national special steel production tasks, and the rest are completed by large steel enterprises jointly with Pute and a large number of small private enterprises, which are distributed in East China, Northeast China, Central China and other areas with active economy or strong industrial base. Leading enterprises: including Northeast Special Steel, CITIC Special Steel, Shijiazhuang Steel, Baosteel Special Steel and Huaigang; Specialized enterprises: TISCO (stainless steel), WISCO (alloy steel plate), ceiling pipe (steel pipe). Among the products of domestic special steel enterprises, 29% are non-special steel products (plain carbon steel), the proportion of special steel products is only 30%, and the remaining 4 1% products are excellent steel. The Twelfth Five-Year Plan for Iron and Steel Industry (Draft) specifies the key directions of special steel: high-speed railway, urban rail transit, offshore engineering and offshore oil exploitation, large and special performance ships and ships, and energy-saving and environment-friendly vehicles. Focus on the development of key steel products such as high-speed railway steel, high-strength automobile steel, advanced power steel, tool steel and special heavy forging materials, and research and develop extra-thick steel plates for thermal power and nuclear power, high-pressure boiler tubes and oriented silicon steel with high magnetic induction and low iron loss for transformers over 250,000 VA. \x0d\ steel is the most important material for automobiles, accounting for more than 70% of the body weight, of which special steel accounts for more than 60%. Safety and lightweight are two eternal themes of automobile development, which put forward high requirements for the strength, toughness, purity, stability and fatigue resistance of steel, and high-quality special steel just meets these requirements, so it has been widely used. The automobile special steel produced in China can not fully meet the needs of the development of automobile industry, and there is a lot of room for import substitution in the future. At present, domestic enterprises can provide general materials for automobile assemblies such as engines, gearboxes and steering gears, but the properties of some steel grades are unstable, such as poor purity and carbide uniformity of bearing steel; Engine crankshaft steel and gear steel, some bars and wires of cars and trucks, valve steel of automobile engines, cold heading steel and some free-cutting steels of high-strength standard parts still need to be imported. \x0d\ At present, the manufacturing level of many large-scale complete sets of equipment in China has reached the first class in the world, but the key supporting parts (bearings, gears, molds, springs, chains, hydraulic parts, pneumatic components, seals, fasteners, etc.). ) are heavily dependent on imports, and the degree of localization is very low. The problem of parts is essentially a material problem. Realizing the autonomy of parts will be the key to the transformation and upgrading of the machinery industry in the Twelfth Five-Year Plan, and the development of related materials will be strengthened, which will greatly benefit the special steel industry. The following aims to explain the application of various special steel grades. \x0d\ Spring steel: High fatigue performance is required. \x0d\ Spring steel is mainly used for suspension springs, valve springs, stabilizer support springs and gearboxes. \x0d\ leaf spring. Leaf springs are mainly used for suspension of heavy vehicles. Due to the requirements of portability, comfort and reliability, the hardenability, working stress and fatigue life of leaf spring are challenged. The main steel raw materials of FAW are 60Si2MnA, 55CrMnA and 50CrVA. In addition, we have independently developed some materials, such as 50CrMnSiVNb and 50CrMnMoVNb. With the development of heavy-duty vehicles, the load requirements of leaf springs are gradually increasing. The thickness of spring leaf increases from 13 mm to 24mm, even to 50mm, so good hardenability is needed. In this regard, FAW has developed some new materials, including 50CrMnVA and FAS3550, which have made great contributions to the lightweight of leaf springs. \x0d\ coil spring. Spiral springs are widely used in cars and off-road vehicles, which require good fatigue resistance and elastic attenuation resistance. The material of spiral spring is mainly silicon-chromium series steel, which usually needs heat setting. There are many kinds of spiral springs in FAW, including 60Si2MnA, 50CrVA, 50CrMnVA, 50CrMnSiVNb and 50CrMnMoVNb. As the supporting spring of stabilizer and gearbox, the materials are oil-quenched tempered spring steel wire, low carbon steel wire, 55CrSi and so on. Most of them are produced by Japanese and Korean companies, and the materials in China can't meet the performance requirements. \x0d\ torsion bar spring. Torsion bar spring is used in the suspension system of some light vehicles, which mainly requires good fatigue resistance. There are two kinds of materials with different heat treatment temperatures for torsion bar springs, one is induction quenched carbon steel 45 steel and 40Cr steel; Another kind of spring steel needs tempering, such as 60Si2MnA, 50CrMnVA, 50CrMnMoVNb and 45CrNiMoVA. \x0d\ stabilizer bar. Stabilizer is a device to keep the car body stable when turning, and its shape is usually complicated. Stabilizers are divided into hollow and solid. Hollow stabilizer can reduce the weight by 30%~40% and has been used in heavy vehicles. Typical materials of hollow stabilizer are 30CrMoA, 35CrMoA and 35Mn2. While ordinary materials such as 60Si2MnA, 40CrMnVA, 55CrMnA and 55CrSiA are used for the solid stabilizer bar. \x0d\ Bearing steel: It is often called "the king of steel" \x0d\ At present, there are five kinds of bearing steel used in the world, namely, high-carbon chromium bearing steel, carburized bearing steel, stainless steel bearing steel, high-temperature bearing steel and medium-carbon bearing steel. Bearing steel is often called "the king of steel" because of its high comprehensive quality requirements. Besides making balls, bearing rings, etc. It is sometimes used to make tools, such as molds, measuring tools, taps, etc. \x0d\ Jiangyin Xingcheng Special Steel, Northeast Special Steel, Daye Special Steel and Baote are the main producing areas of bearing steel. Mainly exported to Southeast Asia and Europe. \x0d\ silicon steel: Mechanical properties are the key \x0d\ silicon steel, as a magnetic conductive material, plays a great role in driving motors. Its weight accounts for more than half of the total weight of the drive motor, and its cost accounts for 40% of the total cost. The whole electric drive motor is determined by the electromagnetic properties of silicon steel, and the stability of the drive motor is deeply influenced by the mechanical properties of silicon steel. \x0d\ The driving motor used in automobiles has its own characteristics compared with other driving motors. First of all, the driving motor of the car needs high frequency. In other industries, the frequency of driving motor is usually 60~ 120Hz, while in the automobile industry, the frequency of driving motor is 1000Hz. Secondly, because of the high frequency, the automobile drive motor has to work at a high temperature of about 200℃, which will affect the performance of the material. Finally, high working frequency and high rotating speed (about 12000RPM) determine that automobile motors must have good mechanical properties and fatigue properties. \x0d\ Two-thirds of the silicon steel in the world is produced in China, and the most advanced products are produced by Nippon Steel. In recent years, China has become the largest supplier of silicon steel. The lack of standard materials and testing technology has become an obstacle to the research and development of FAW and even the whole industry. \x0d\ We think we should pay attention to the characteristics of the motor, such as the magnetism, thickness and permanent magnet characteristics of silicon steel. Secondly, we should solve the problems in motor manufacturing, including the formability, weldability and heat treatment of silicon steel. Finally, in the application scheme of motor, the mechanical properties (especially fatigue resistance), physical parameters and insulation layer of silicon steel need to be further discussed. Up to now, FAW has established some standards and detection technologies for silicon steel, and has been engaged in the research on the development, application and detection technologies of silicon steel. \x0d\ At the same time, we should work together to solve the following problems. First of all, the production of motor silicon steel for automobile by iron and steel enterprises should have high economy, reliability and environmental protection. Secondly, the test methods and standards for high-temperature and high-frequency performance of silicon steel should be formulated. Third, I hope that steel enterprises can enjoy the data of the designed automobile motor or cooperate in research. \x0d\ Non-quenched and tempered steel: high strength and toughness \ x0d \ After 2000, FAW cooperated with Northeast Special Steel Group Co., Ltd. to develop fracture-separated connecting rods FAS227 1 and FAS2237, front axle steel FAS2225, crankshaft FAS2239 and low-cost non-quenched and tempered steel FAS224 1. FAW also made the FAS2340 scheme for the front axle. \x0d\ The development trend of non-quenched and tempered steel is to improve strength and plasticity. Therefore, in the process of research and promotion, we should pay attention to the following points: First, the application of non-quenched and tempered steel is beneficial to the automobile industry and iron and steel enterprises, and both sides should jointly develop and promote this product. Secondly, we believe that we should focus on developing non-quenched and tempered steel with high strength and toughness. Third, the standard of non-quenched and tempered steel should be continuously improved. Finally, we should continue to study low-cost non-quenched and tempered steel. \x0d\ Bolts: bolts are widely used in the automobile industry \x0d\ Today, the automobile industry is the largest consumer market for bolts, and its demand accounts for 23.2% of the total sales of bolts. China's bolt production accounts for about 25% of the world, of which 40% is exported. China has become the largest producer and exporter of bolts. According to statistics, a car or light vehicle with a net weight of 50kg has about 4,000 bolts, while a medium or heavy vehicle with a weight of 90kg has about 7,500 bolts, of which 4/5 are high-strength bolts. The cost of bolts accounts for 2.5%~3% of a car and 40% of the total number of parts. \x0d\ Most bolts of FAW are provided by a fastener company in Jilin, and the materials they use have certain standards. For example, 12.9 grade bolts are made of ML42CrMo(SCM440) steel, 10.9 grade bolts are made of ML35CrMoZ(SCM435) steel, and 8.8 grade bolts are made of ML40Cr steel. An example of high-strength material for bolts is ML35CrMo(GB/T6478-200 1) in China standard and 34CrMo(ISO863. 1) in international standard. In addition, KAMAX company in Germany and AoyomaSeisakusho company in Japan also produce this material at the same time. As engine parts, high-strength bolt materials are usually imported, and the models imported from Germany are usually 27MnB4, 23MnB4, 32CrB4 and 32CrMo4(DINEN 10263-4). The models imported from Japan are usually SCM435 and SCM440(JISG4053), and the material is mainly 10.9 grade bolt boron steel. \ x0d \ After 2000, the demand for high pressure resistance and light weight in automobile and machinery industries promoted the improvement of bolt strength. The application of 12.9 bolts has been widely studied and solved in many countries in the world. FAW put forward some suggestions to steel suppliers through the problems encountered in actual use. First of all, the quality and reliability of bolt steel need to be improved. Reducing the content of sulfur and phosphorus to improve the purity of steel can improve the ductility of steel, and then improve the reliability and working life of bolts. Secondly, iron and steel enterprises should strengthen the improvement of product quality and develop high temperature resistant bolts. \x0d\ Gear steel: Test standards are constantly established \x0d\ In FAW, gear steel is mainly used for engines, gearboxes and axles. Faw used Cr-Mn-Ti series gear steel developed by the Soviet Union. After the introduction of technology in the 1990s, some new steel grades were independently developed, including Mn-Cr steel, Cr-Mo steel and Cr-Ni-Mo steel. With the continuous improvement of gear steel and gear processing equipment, FAW's gear steel has reached the ME strength grade in ISO standard. At present, FAW has 22 gear steel standards, seven of which are usually used for trucks, namely 20CrMnTiH, 20crmmoh, 20crmmoh, SAE8620H, FAS3220H and FAS3420H. In the process of developing gear steel, a large number of experimental material performance tests must be carried out, including drawing CCT curve and TTT curve, rotating bending fatigue test, bending fatigue test, contact fatigue test after heat treatment, deformation test and basic characteristics test. The quality of gear steel should be strictly controlled by the steel supplier, including hardening ability and banded structure. FAW hopes to cooperate with iron and steel enterprises to formulate the belt structure standard of gear steel. \x0d\ carbon structural steel: carbon structural steel with good mechanical properties and processability \x0d\ for short. Specifically, its carbon content is less than 0.08%. Compared with ordinary carbon steel, it is a high-quality carbon structural steel with better quality, strict requirements on chemical composition and mechanical properties, and low content of impurities such as phosphorus and sulfur. \x0d\ The types of carbon steel can be divided into two groups according to the different manganese content: normal manganese content (0.25%-0.80%) and high manganese content (0.70%- 1.20%), and the latter has better mechanical properties and processability. The types of carbon steel are divided into three categories according to the different carbon content: low carbon steel, medium carbon steel and high carbon steel. \x0d\ Carbon bonded steel is used for various mechanical structural parts, metal products and tools, and also for building factories, bridges, boilers, ships, etc. The brand of carbon steel is represented by numbers, which are small and have low carbon content. Low carbon steel, including carbon-bonded steel, has good plasticity and toughness, and often undergoes surface heat treatment to produce parts with hard and wear-resistant surfaces and good center. Low carbon steel is used for rolling thin plates and deep drawing products. Medium carbon steel, including carbon steel, has the following brands: 15# carbon steel, 20# carbon steel, 35# carbon steel, 45# carbon steel and so on. After quenching and tempering heat treatment, it has moderate properties and high comprehensive mechanical properties. The purpose of carbon steel is to manufacture small-sized quenched and tempered parts, including pull rods, bushings, gears, piston pins, fasteners and so on. High carbon steel, including carbon steel, has high strength and hardness, and its brands are: 50# carbon steel, 55# carbon steel, 60# carbon steel and 75# carbon steel. The purpose of high carbon steel is to make springs and parts that require wear resistance. Carbon-bonded steel has poor hardenability and is not suitable for manufacturing parts with high performance requirements, large cross-sectional size or complex shape. \x0d\ carbon steel is a common carbon structural steel (including (a) q195; (b) Q2 15(A、B)； (c) Q235(A、B、C)； Q255(A、B)； (e) Q275, which is also a common carbon structural steel in construction and engineering steels classified by use.