1 spring steel is designed to manufacture a variety of springs and elastic components, or similar performance requirements of the structural components of the main material. 1. ① high performance elastic limit σe and yield ratio σs / σb, to ensure excellent elastic properties, which can absorb a lot of flexibility without plastic deformation; ② high fatigue limit, fatigue damage is the most important form of spring First, the fatigue properties of steel composition and structure than the other, is also largely affected by the quality of steel metallurgy (such as non-metallic inclusions) and spring surface quality (such as decarburization) effects; ③ sufficient ductility and toughness in order to prevent impact fracture; ④ other properties, such as good heat treatment and plastic processing performance, to work under special conditions of heat resistance or corrosion resistance requirements.
    2. Composition characteristics of carbon and alloy steel elements in the content and effect of: (1), the carbon in general, carbon spring steel wc = 0.6% ~ 0.9%, alloy spring steel wc = 0.45% ~ 0.70%, after quenching tempering temperature and tempering in the trust's body after the tissue has been able to better ensure the performance requirements of the spring. (2) alloying elements for general-purpose alloy spring steel is generally low alloy steel. Plus elements of the main Si, Mn, Cr, etc., whose main role is to enhance hardenability, solid solution strengthening and improving temper resistance matrix; Adjuvant elements Mo, W, V and other strong carbide forming elements, the main role of prevent decarburization caused by defects in Si, Mn-induced defects and improve the tempering heat stability and heat resistance.

    3. Common spring steel Table 12-10 for our common spring steel grades, performance characteristics and main uses, the composition, heat treatment and mechanical properties may refer to the relevant national standards (such as GB1222-1984). Table 12-10 spring steel grades commonly used in the main performance characteristics and use of performance characteristics of types of steel products to use the amount of carbon spring steel 65 Mn ordinary hardness, strength, yield strength is high, but poor hardenability, good heat resistance, under dynamic loading and fatigue loading capacity of the low price low, not high temperature and more used for small springs <12mm or unimportant large amount of Mn 65Mn spring 7085 high hardenability, mechanical properties superior to carbon steel, but more sensitive to the price of thermal low, a large amount, making a variety of small cross-section <15mm of flat spring, springs, shock absorbers and clutch springs, brake shaft, etc. spring steel Si-Mn alloy system 55Si2Mn high strength, good elasticity , anti-tempering stability is good; but easy to decarburization and graphitization. With B significantly improved hardenability steel main spring steel class, very versatile and can produce a variety of medium cross-section <25mm important springs, such as cars, tractors spring, spiral spring 60Si2Mn55Si2MnB55SiMnVBCr Department 50CrVA excellent hardenability, tempering high stability, low tendency to decarburization and graphitization; good mechanical properties, there is some corrosion resistance, including V, Mo, W and other elements of the spring has a temperature resistance; as are high quality steel, so the fatigue further improve the performance of a large heavy load for the manufacture of large size (50 ~ 60mm) of the important spring, such as engine valve springs, conventional weapons and bombs to take the hook spring, spring breakers; thermal springs, such as boiler safety valve springs, injectors spring, cylinder expansion ring, etc. 60CrMnA60CrMnBA60CrMnMoA60Si2CrA60Si2CrVA1) carbon spring steel (ie, non-alloy spring steel) its cheap but poor hardenability, smaller cross-section for non-critical springs, of which 65,65 Mn most commonly used. 2) Alloy spring steel according to the different types of main alloying elements increase can be divided into two categories: Si-Mn spring steel and Cr Department of Department of spring steel. The former high hardenability than steel, the price is not very expensive, so the most widely used cross-sectional dimension greater than 25mm of various types of springs, 60Si2Mn is the typical representative; hardenability which is better, overall mechanical high-performance, easy spring surface decarburization, but the price is relatively high, generally used for important cross-section of a larger size spring, 50CrVA is the typical representative.

    4. Heat-treated spring steel heat treatment depends on the characteristics of the spring forming method of processing, can be divided into hot and cold formed springs springs forming two categories: 1) hot forming spring section size> 10mm variety of large and complex shape of the hot springs are used shape (such as hot-rolled, hot rolled), such as automobiles, tractors, trains the spring and coil spring. The simple process route: flat or round the next bend or winding material → heating → → quenching tempering temperature shot peening surface treatment, using state of the organization's care for the tempered body. Shot peening can strengthen and improve the surface quality of the spring surface, significantly improved fatigue performance. 2) cold forming spring section size <10mm in a variety of small springs can be used cold forming (such as cold roll, cold-rolled), such as the instrument of the coil spring, spring, and spring and so on. Spring before the forming of such cold pull (cold), quenching or tempering in lead bath temperature after quenching, cold drawing temperature (rolling) to strengthen; then the cold forming process, this process will further strengthen the metal, but also produced a larger internal stress and brittleness, it should be low to the subsequent stress annealing (usually 200 ~ 400 ℃).