1. Total amount of steel used for suspension springs
Suspension springs used in automobile industry are divided into leaf springs and circular springs (also known as spiral suspension springs).
Round springs are used in automobiles. The diameter of steel used is 9 ~ 16 mm, and the variety is cold-drawn round steel wire. In addition, there are some mini-cars, van suspension springs and motorcycle damping springs. Round springs are also used.
Light trucks, medium and heavy trucks and passenger cars use leaf springs, the size is 6 ~ 30× 50 ~ 140 mm, and the variety is flat spring steel. Trucks generally use equal cross-section leaf springs, while heavy trucks use equal cross-section front springs and variable cross-section leaf springs. Passenger cars generally use variable cross-section leaf springs. It is difficult to produce variable cross-section, and Dongfeng is the only company in China that has imported British equipment with production capacity.
The development of automobile industry will determine the use of leaf spring and round spring. According to statistics, at the end of 2004, the output of suspension springs of nearly 50 enterprises was about 500,000 tons, equivalent to about 550,000 tons of spring steel, accounting for 90% of the total consumption in China. Therefore, the total demand of spring steel for automobile suspension springs in China is about 600,000 tons, including 560,000 tons of flat spring steel and 40,000 tons of spring steel wire.
2. Unit consumption of steel for suspension spring
According to Dongfeng Motor Suspension Spring Co., Ltd., a 5-ton truck (model 140) has a leaf spring on the front axle of about 50kg, a leaf spring on the rear axle of about 50-60kg, and a leaf spring on the auxiliary axle of about 70-80kg. In addition, if the steel utilization rate is 90%, a 5-ton truck needs a total of 200 ~ 300 kg.
An 8-ton truck (model 153) weighs about 90kg for the front axle, 90kg100kg for the rear axle and 70kg/80kg for the auxiliary axle. In addition, a 5 ton truck needs about 300kg in total.
A 13 ton heavy truck needs about 400kg leaf spring for each truck.
Taking four suspension springs as an example, each bus needs about 200 ~ 300 kg leaf springs on average.
Take four suspension springs (the first two and the last two) as an example, each car needs about 15kg of spring steel wire on average.
3. The suspension spring is made of steel, and the type, specification and requirements of steel.
(1) spring flat steel
Light trucks, medium and heavy trucks and passenger cars use leaf springs, and the usage of steel grades is as follows:
The representative specifications of 60Si2Mn are:10× 60 (65,75,90, 100)mm,1× 60 (70,75) mm, and the specifications of spring square steel are1.
The service specifications of 55SiMnB spring flat steel are: 10×75mm,1× 70 (90) mm, 12×70mm, 12×90mm,1.
The specification of 50CrVA is 12×90mm, and the annual consumption accounts for about 30% of the total.
In addition, the less used steel grade is 65Mn, with the representative specification of 10×75mm, the representative specification of 35CrMnSi is 10×75mm, and the representative specification of 60CrMnA is 12×60mm. Leaf spring manufacturers also use a small amount of Q235 flat steel and 70 # cold-drawn steel wire. Q235 flat steel is used as the connecting structure, and the specifications are 4×25mm, 5×25mm and 6×30mm. Cut 70 # coil cold-drawn steel wire into fine particles and spray them on the surface of heat-treated steel plate to remove the regenerated oxide scale. The specification of steel wire is1.2mm. ..
(2) Spring steel wire
Circular springs are used for suspension springs of cars, some mini-cars and vans, and shock absorption springs of motorcycles. Steel grades include 60Si2MnA, 55CrSi(SUP 12), 50GrVA and other brands.
The car has four suspension springs, two in the front and two in the back. Generally, the diameter of the front is slightly smaller than that of the back, and the diameters used in various models are also different. What are the specifications? 9 ~16mm.
The steel used for automobile suspension spring steel wire is high-grade spring steel wire, which requires high strength, long fatigue life and good shock absorption. Therefore, there are requirements for the chemical composition, quantity and shape distribution of inclusions, surface quality, decarburized layer, microstructure and mechanical properties of spring steel wire. Suspension spring requires decarburization layer less than 0.5% of the diameter, polished surface, long fatigue life, strict dimensional tolerance and defect-free delivery. The usual thermal processing methods are difficult to meet the requirements of users. Therefore, the spring for automobile spiral suspension is gradually changed from hot forming to cold forming, and the spiral spring is made by drawing and heat treatment (quenching and tempering to obtain martensite structure). The development direction of suspension spring steel wire is to reduce carbon content, reduce decarburization tendency and improve plastic formability and elastic attenuation resistance.
4. Major domestic steel suppliers
(1) Major domestic producers of flat spring steel
At present, the annual demand for raw materials for automobile spring flat steel is about 560,000 tons, and the quality, variety and specifications of domestic spring flat steel can basically meet the requirements of users. Take Dongfeng Motor Leaf Spring Co., Ltd. as an example, all the spring flat steel purchased by Dongfeng Motor Leaf Spring Co., Ltd. are localized, and mainly purchase Yongtong Iron and Steel Co., Ltd., Jiangxi Changli Automobile Spring Co., Ltd., Daye Special Steel Co., Ltd., Jiangyin Xingcheng Iron and Steel Co., Ltd. and other enterprises. The domestic enterprises that can produce spring flat steel are briefly introduced as follows:
Jiangxi Changli Automobile Spring Co., Ltd.: Located in the eastern suburb of Nanchang City, Jiangxi Province, Jiangxi Automobile Leaf Spring Co., Ltd., a holding subsidiary, is a joint-stock company established by jiangling motors Group, Guangzhou Gaotian Co., Ltd., Jiangxi Shangrao Xinjiang Industrial Group and Jiangxi Imported Automobile Parts Co., Ltd. It is a member of China Auto Parts Industry and Trade Group and a designated manufacturer of auto parts in China. The main production equipment is imported from Japan, with an annual output of 60,000 tons of spring flat steel. The flat steel with single and double grooves is 3 ~ 10 #, the flat spring steel is (5 ~ 22) × (50 ~ 120) mm, the length is 4.8mm, and the materials are 55Si2Mn, 60Si2Mn, 55SiMnVB, 55SiMnoBRe, 50CrVA, etc.
Xinjiang Bagang: The main products produced are spring flat steel (including double-groove and T-shape) series products, with specifications of 6× 50 ~ 20× 100 mm, length of 6 ~ 9 m and annual output of about 60,000 tons.
Sichuan Chuanwei Iron and Steel Group Co., Ltd.: The main products are spring flat steel with specifications of (50 ~ 120) × (5 ~ 30) mm and steel grades of 60Si2Mn, 55SiMnVB and 60CrMnA.
Fushun xinfu iron and steel co., ltd: the main products are 6 ~ 25× 60 ~ 120 mm spring flat steel products.
Sichuan Chuandong Automobile Parts Manufacturing Co., Ltd.: mainly produces automobile leaf springs, rolling various specifications of automobile spring flat steel, automobile wheels, suspension parts and so on. The annual output of automobile spring flat steel is 654.38+10,000 tons, and that of automobile leaf spring is 30,000 tons.
Shenyang Toyo Iron and Steel Co., Ltd.: The main products are (6 ~ 20) × (80 ~ 120) mm spring flat steel, and the steel grades are 55SiMn and 60Si2Mn.
Daye Special Steel: The annual production capacity of spring flat steel can reach 654.38+10,000 tons.
Zhengzhou Yongtong Special Steel Co., Ltd.: The main products are spring flat steel and spring round steel. The specification of flat steel varies from 5 ~ 20mm to 50 ~150 mm.
Huaigang Group: produces various specifications of spring flat steel, mainly 60Si2Mn and 55SiMnVB, with an annual output of 20,000 tons.
(2) The situation of major domestic spring steel wire production enterprises.
At present, the annual demand of raw materials for automobile spring steel wire is about 40,000 tons, but the quality, variety and specifications of domestic spring steel wire can not meet the requirements of users, especially the suspension spring steel wire with high requirements for automobile matching needs to be imported from abroad, and the main importing countries are Japan, South Korea, Sweden and France.
In recent years, a number of enterprises such as Zhengzhou No.2 Pilot Plant, Tianjin Dihua, Changsha Spring, Nanjing Soochow and Shanghai Song Yin have used wire rods from Kobe, Sumitomo and Baosteel in China, and the steel grades used are 60Si2MnA, 55CrSi(SUP 12) and 50GrVA. There is still a gap between the quality of domestic products and similar products in Japan and South Korea. However, due to the relatively low price, some spring factories provide parts such as mini-cars, van suspension springs and motorcycle damping springs.
At present, the main domestic producers of alloy spring wires are Baosteel, Shougang Special Steel Plant, Dalian Steel Plant and Shanghai No.5 Iron and Steel Plant. Baosteel and Shanghai Steel No.5 Plant have quality advantages, but their prices are relatively higher than those of other steel mills. The spring steel wire produced by Baosteel High-speed Wire Rod Factory has brands such as 55SiCr, 50CrV and 60Si2MnA, among which 55SiCr spring steel wire has been used in cars such as Mazda, Changan, Santana, Jetta and Fukang after drawing, heat treatment and coil spring treatment.