Bearing steel pipe theoretical weight table.
The physical properties of bearing steel are mainly based on checking the microstructure, decarburization layer, non-metallic inclusions, and low-frequency organization. In general are delivered in hot-rolled annealed, cold-drawn annealed. Delivery condition should be specified in the contract. The low-frequency organization of the steel must be free of shrinkage, subcutaneous bubbles, white spots and microscopic porosity. The central laxity and general laxity shall not exceed 1.5 grade, and the deviation shall not exceed 2 grade. Annealing organization of the steel should be uniformly distributed fine-grained pearlite. Decarburization layer depth, non-metallic inclusions and carbide unevenness should be in line with the provisions of the relevant national standards.
In general, the diameter less than 20mm should be packed for delivery, more than 20mm can be delivered bare. Specific packaging requirements, depending on the requirements of the contract signed between the two sides, such as, hexagonal package, length difference, export of the general to add the outer packaging, etc.. For cold-drawn steel should be coated with anti-rust oil, some domestic manufacturers in urgent need of goods, can not anti-rust, or its processing in complete sets of rings to do oil removal treatment. Before leaving the factory, the goods should be accompanied by a quality assurance certificate, indicating the steel number, furnace number, weight, specifications, chemical composition, inspection standards and test results.
Production and manufacturing methods.
The production of bearing steel tube bearing special steel grades are as follows (marked with “roll” G): chromium bearing steel such as GCr6, GCr9 (SiMn), GCrl5 (SiMn); chromium-free bearing steel such as GSiMnV (Re), GSiMnMoV (Re), GMnMoV (Re); carburized Bearing steel such as G20CrMo, G20Cr2Mn2Mo; high carbon chromium stainless bearing steel such as 9Cr18 (Mo), etc..
Bearing steel smelting quality requirements are very high, need to strictly control the content of sulfur, phosphorus, hydrogen and other non-metallic inclusions and carbide number, size and distribution, because the number, size and distribution of non-metallic inclusions and carbide on the service life of bearing steel has a great impact, often bearing failure is in the large inclusions or carbide around the expansion of micro-cracking. Inclusion content and steel oxygen content is closely related, the higher the oxygen content, the more the number of inclusions, the shorter the life. The larger the particle size of inclusions and carbides, the more unevenly distributed, the shorter the service life, and their size, distribution and the use of the smelting process and smelting quality is closely related to the production of bearing steel is now the main process of continuous casting and electric furnace smelting + electroslag remelting process smelting, and a small number of vacuum induction + vacuum self-consumption of double vacuum or + multiple vacuum self-consumption and other processes to improve the quality of bearing steel.
Bearing steel smelting new technology.
Bearing steel pipe is mainly used for manufacturing rolling bearing rolling body and collar.
As the bearing should have long life, high precision, low heat generation, high speed, high rigidity, low noise, high wear resistance and other characteristics, so the bearing steel tube should be required to have: high hardness, uniform hardness, high elastic limit, high contact fatigue strength, must toughness, certain hardenability, corrosion resistance in the atmosphere of the lubricant. In order to achieve the above performance requirements, the bearing steel tube chemical composition uniformity, non-metallic inclusions content and type, carbide particle size and distribution, decarburization and other strict requirements. Bearing steel in general to high quality, high performance and multi-species direction. Bearing steel according to the characteristics and application environment is divided into: high-carbon chromium bearing steel, carburized bearing steel, high-temperature bearing steel, stainless bearing steel and special bearing materials.
To adapt to high temperature, high speed, high load, corrosion resistance, radiation resistance requirements, the need to develop a series of new bearing steel with special properties. In order to reduce the oxygen content of bearing steel pipe, the development of vacuum smelting, electroslag remelting, electron beam remelting and other bearing steel pipe smelting technology. And large quantities of bearing steel pipe smelting by electric arc furnace smelting, the development of various types of primary refining furnace plus refining outside the furnace. At present, the use of capacity greater than 60 tons primary refining furnace + LF/VD or RH + continuous casting + continuous rolling process production of bearing steel pipe to achieve high quality, high efficiency, low energy consumption of the purpose. In the heat treatment process, from the bottom of the car type furnace, hood type furnace development into a continuous controlled atmosphere annealing furnace heat treatment. At present, the longest continuous heat treatment furnace type is 150m, processing and production of bearing steel pipe spheroidized organization is stable and uniform, decarburization layer is small, low energy consumption.