Bearing steel is used to make balls, rollers and bearing rings of steel. Bearing steel has high and uniform hardness and wear resistance, and high elastic limit. The chemical composition of bearing steel uniformity, non-metallic inclusions content and distribution, carbide distribution and other requirements are very strict, it is one of the most stringent of all steel production in steel requirements. International Organization for Standardization ISO 1976 some common bearing steel into the international standard, the bearing steel is divided into: full hardenability type bearing steel, case hardened bearing steel, stainless steel bearings, high temperature bearing steel and other four categories a total of 17 steel. Introduction bearing steel is used in the manufacture of rolling bearings ball, roller and steel sleeve, etc., can also be used for the production of precision measuring tools, Die, machine screw and diesel pump precision coupling. Name: bearing steel English: bearing steel 2 prospects precision bearings and other basic mechanical foundry industry has become a national focus on the development of "second five" industry, in order to achieve economic growth targets two sessions around the dense urban infrastructure construction projects started, bearing steel market demand will also be released. With the sustained and rapid development of the bearing industry, bearing steel market outlook is promising. Domestic bearing steel manufacturers are actively developing new varieties of bearing steel, bearing manufacturing industry based on high-end products is the main trend in the future. In order to achieve economic growth targets two sessions, local urban infrastructure construction project set off a climax, started intensive railway, affordable housing, water, ports, airports and other major projects led to the recovery of construction machinery manufacturing industry, stimulating demand for construction machinery, bearing steel demand also will be released. At the same time iron ore, coke, steel and other raw materials, high chrome prices continued to run high, the bearing steel production costs continue to rise, pushing the cost of rigidity, prompting steel prices up, thus further promote the rise bearing steel market prices, which two favorable factors steady growth stimulating domestic demand. Industry Insights research data "2013 China bearing steel industry depth research report" shows that the domestic bearing manufacturing industry strong momentum of development, bearing steel market is stable and good will to bring positive effects. Substantial growth in a number of high-end bearing demand, such as aerospace bearings, machine tool spindle speed precision bearings, high-speed spindle bearings, precision bearings photovoltaic industry, machine tools, high-speed rail bearings, automotive bearings, crane sheave bearings and so on. 3 Product Overview bearing steel is used to make balls, rollers and bearing rings of steel. Bearing under immense pressure and friction at work, it requires a high and uniform bearing steel hardness and wear resistance, and high elastic limit. The chemical composition of bearing steel uniformity, non-metallic inclusions content and distribution, carbide distribution and other requirements are very strict, it is one of the most stringent of all steel production in steel requirements. International Organization for Standardization ISO 1976 some common bearing steel into the international standard, the bearing steel is divided into: full hardenability type bearing steel, case hardened bearing steel, stainless steel bearings, high temperature bearing steel and other four categories a total of 17 steel. Some countries add a category for the special purpose of bearing steel or alloy. China has included the standard bearing steel and ISO classification similar to corresponding high carbon chromium bearing steel, carburizing bearing steel, corrosion resistant stainless steel bearings, high temperature bearing steel four categories. Nearly fifty years our country still bearing steel and bearing steel with the materials, such as chromium-bearing steel, carbon bearing steel, bearing steel and special purpose alloys, metal ceramics has made great progress. Carbon chromium bearing steel GCr15 is the world's largest production capacity of bearing steel, carbon Wc about 1% chromium content Wcr about 1.5 percent, from 100 years since its inception in 1901, the main component essentially unchanged, with advances in science and technology, research any continuing, continuously improve product quality, account for over 80% of the world total production of bearing steel. So we said bearing steel without special instructions, that means GCr15. Chemical composition: GB, the rule of standard, Japanese standard chemical composition of steel is shown in Table 4 main technical standard bearing steel production is mainly the implementation of GB / T18254-2002 standards and adapt to user requirements forging bearing Laiwu GCr15JD quality agreement, which GCr15JD Agreement strict quality requirements in GB / T18254-2002 standard, GCr15JD requires oxygen content ≤10ppm, center segregation level ≤1.0 level, composition control, length and size deviation etc. strict GB / T18254-2002 standard. Process 50 t UHP EAF → 60 tons of LF refining furnace → 60 吨 VD vacuum treatment → steel rectangular billet continuous casting (260mm × 300mm, 180mm × 220mm) → slow cooling or hot rolled send → → finishing → Inspection storage. Quality Performance To meet the above requirements on the dynamic properties of the bearing, bearing steel material made the following basic performance requirements: 1) high contact fatigue strength, 2) should have a high hardness after heat treatment or can meet the performance requirements of bearings hardness, and 3) high wear resistance, low friction coefficient, 4) high elastic limit, 5) good impact toughness and fracture toughness, 6) good dimensional stability, 7) good rust resistance, 8 ) good cold, heat processing performance. The basic requirements for bearing steel according to the above basic requirements of bearing steel, bearing steel metallurgical quality make the following basic requirements; ① strict chemical composition requirements. General bearing steel mainly carbon chromium bearing steel, which is about 1% carbon content, added about 1.5% chromium, and eutectoid steel containing a small amount of manganese, silicon element. Chromium heat treatment can improve performance, increase hardenability, microstructure uniformity, tempering stability, but also can improve the rust resistance and grinding properties of the steel. But when the chromium content exceeds 1.65%, it will increase the retained austenite after quenching, reducing the hardness and dimensional stability, increased carbide inhomogeneity, reducing steel toughness and fatigue strength. To this end, high-carbon chromium bearing steel in the amount of chromium containing the general control of 1,65% or less. Only by strictly controlling the chemical composition of bearing steel, bearing performance can be met by the heat treatment process on microstructure and hardness. ② high dimensional accuracy, for use in high-speed upsetting forging rolled annealed bar, there should be a higher demand for its dimensional accuracy. Rolling steel requires high dimensional accuracy of steel, this is because most of the pressure bearing parts have been formed. In order to save material and labor productivity, most bearing rings are formed through forging, cold heading steel ball through molding or hot-rolled, roller small size is formed through cold heading. If the dimensional accuracy of steel is not high, it can not accurately calculate cutting the size and weight, but can not guarantee the quality of products bearing parts, are likely to cause damage to equipment and tooling. ③ particularly stringent purity requirements. Purity steel refers to the number of non-metallic inclusions contained in the steel, the higher the purity, the less non-metallic inclusions in steel. Bearing steel oxides, silicates and other harmful inclusions lead to early bearing fatigue spalling, mainly due to a significant reduction in bearing life. Especially brittle inclusions most damaging, since the easily peeled off from the metal substrate in the process, severely affecting the surface quality of the bearing parts after finishing. Therefore, in order to improve the life and reliability of bearings, bearing steel must reduce the content of inclusions. ④ strict and low magnification microscopy (high magnification) organizational requirements. Bearing Steel low magnification refers to the general loose, loose and flat center analysis, microscopy (high magnification) organizations, including organizations annealed steel, carbide mesh, ribbon and liquid analysis and so on. Liquation carbide hard and brittle, it's the same dangers and brittle inclusions. Reduce the impact of network carbide toughness, uneven and organized as easily deformed during hardening and cracking. Carbide strip annealing and quenching and tempering influence organizations and contact fatigue strength. Low, the merits of high-powered organization has a great influence on the performance and service life of rolling bearings, so bearing material standards for low, high-powered organization has strict requirements. ⑤ particularly stringent requirements for surface defects and internal defects. Bearing steel, the surface defects including cracks, slag, burrs, scarring, oxide and other internal defects, including shrinkage, bubbles, white spots, severe osteoporosis and segregation. These defects for bearing machining, bearing performance and life have a great impact in the bearing material standards clearly does not permit the emergence of these defects. ⑥ carbide of strict requirements. Bearing steel, carbide if severe uneven distribution in the heat treatment process likely to cause non-uniform microstructure and hardness of steel inhomogeneity has a greater impact on the contact fatigue strength. In addition, severe carbide heterogeneity is also easy to crack when bearing parts quenching, carbide heterogeneity will result in reduced bearing life and therefore, in the bearing material standards for different specifications of steel have clear special requirements. ⑦ surface decarburization depth strict requirements. In the standard bearing materials for steel surface decarbonization layer has strict rules, if the surface carbon layer outside the specified range of the standard, and in the process prior to heat treatment in its entirety and not removed, then in the process of heat treatment and quenching prone to quench cracking, resulting in scrapped parts. ⑧ other requirements. Also bearing steel smelting method, oxygen content, annealed hardness, fracture, residual elements, sparks tested in bearing steel standard, delivery status, identification and other strict requirements. The physical properties of the physical properties of the bearing steel is mainly to check the microstructure, decarburization, non-metallic inclusions, mainly low magnification. Generally are hot-rolled annealing, cold drawn annealed delivery. Delivery status should be specified in the contract. Steel low magnification must be free of shrinkage, skin bubbles, white point and microscopic pores. Center porosity, generally can not be more than 1.5 osteoporosis, segregation may not be more than two. Annealing organization should be fine-grained steel pearlite evenly distributed. Decarburization depth, non-metallic inclusions and carbide of shall comply with the relevant national standards. Our product range has produced 5 carbon chromium bearing stainless steel, the main steel have 9Cr18; carburizing bearing steel, the main steel are G20CrMo; chromium bearing steel, the main steel are GCr15. Also known as high carbon chromium bearing steel steel, carbon content ωc is about 1% chromium content ωcr 0.5% -1.65%. Bearing steel is divided into high-carbon chromium bearing steel, non-chromium bearing steel, carburizing bearing steel, stainless steel bearings, high temperature bearing steel and bearing steel shielded six categories; 6 manufacturing method of smelting demanding quality bearing steel , the need for strict control of sulfur, phosphorus, hydrogen content, and the number, size and distribution of non-metallic inclusions and carbides, because the number, size and distribution of non-metallic inclusions and carbides influence on the useful life of bearing steel was large, often bearing failure is in large microcracks or carbide inclusions generated around extended from. And a content of inclusions in steel is closely related to the oxygen content, the higher the oxygen content, the more the number of inclusions, the shorter the life. The larger inclusions and carbide particle size distribution more uneven, life is also shorter, and their size distribution is closely related to the quality of the smelting and refining processes used in the production of bearing steel main process is continuous casting and hot plates + ESR smelting smelting technology, as well as a small amount of vacuum induction vacuum arc of double vacuum or + repeatedly vacuum consumable and other technology to improve the quality bearing steel. 7 Category usage: current bearing steel used in the world there are five main categories, namely high-carbon chromium bearing steel, carburizing bearing steel, stainless steel bearings, high temperature bearing steel, carbon bearing steel. Uses: In addition to doing ball bearing rings substandard, sometimes used to make tools, such as dies, gauges, taps and so on. Production areas of China Dalian Steel, Daye Steel is a major producer of bearing steel production. At present, exports to Hong Kong and Southeast Asia. China's major sources of imports bearing steel imports from Japan and Germany.