The innovation of the bearing steel technology and the general direction

The rotation of the bearing steel is mainly used in the manufacture of rotating bearing body and ring. Due to bearing should have long life, high precision, low calorific value, recommend suite, high rigidity, low noise, high abrasion resistance and other characteristics, so the requirement of bearing steel should have: high hardness, uniform hardness, high elastic limit, high must contact fatigue strength, toughness and hardenability, in atmospheric corrosion resistance of lubricant. In order to achieve the performance requirements, the uniformity of the chemical composition of bearing steel, non-metallic inclusion content and type, strict carbide particle size and distribution, decarburization, etc. Bearing steel in general to develop in the direction of high quality, high performance and many varieties. According to the characteristics and application environment of bearing steel is divided into: high carbon chromium bearing steel, high temperature carburizing bearing steel, bearing steel special bearing, stainless bearing steel and special materials. 

In order to adapt to high temperature, high speed, high load, corrosion resistance, resistance to radiation, need to develop a series of new type of bearing steel with special performance. To decrease the oxygen content of bearing steel, the development of the vacuum smelting, esr, electron-beam remelting of bearing steel smelting technology. And the mass of bearing steel smelting electric arc furnace smelting, early developed into all kinds of smelting and refining outside the furnace. At present, the use of early capacity greater than 60 tons + LF/VD and RH refining furnace, continuous casting and rolling process of bearing steel production, in order to achieve the purpose of high quality, high efficiency, low energy consumption. In terms of heat treatment process, from the car type furnace, bell type furnace developed into the continuous controlled atmosphere heat treatment of annealing furnace. At present, the longest continuous type heat treatment furnace is 150 m, processing production of bearing steel spheroidizing stable and uniform, the decarburization layer is small, low energy consumption. 

Since the 1970 s, along with economic development and industrial technical progress, application scope of bearing; And the development of international trade, and promote the internationalization of bearing steel standard and new technology, new technology and new equipment development and application of high efficiency, high quality, low capital supporting technology and process equipment arises at the historic moment. Japan and Germany are built high cleanliness, high quality of bearing steel production line, make the output of steel increased rapidly, the quality of the steel and fatigue life of substantial progress. Japan and Sweden, production of bearing steel oxygen levels fall below 10 PPM. In the late 80 s, the advanced level of Japanese sanyo special steel company is a 5.4 PPM, achieved the level of vacuum remelting bearing steel. 

Bearing contact fatigue life is sensitive to the uniformity of steel group. Progress cleanliness (reducing impurity elements and inclusion content in steel), prompting the non-metallic inclusions in steel and carbide tiny uniform distribution, can improve contact fatigue life of bearing steel. Bearing steel using state organization should be tempered martensite matrix uniformly distributed on the fine carbide particles, such organizations can give the performance of the bearing steel needed. High carbon steel bearing the main alloy elements carbon, chromium, silicon, manganese, vanadium, etc. 

How to get the ball organization is an important topic in bearing steel production, controlled rolling of cooling is one of the important production technology advanced bearing steel. By controlled rolling and cold rolling, quick to eliminate carbide network and obtain appropriate preparation group, bearing steel ball annealing can shorten the time, carbide, progressive fatigue life. In recent years, Russia and Japan with low temperature rolling (below 800 ℃ ~ 850 ℃), using air cooling after rolling and annealing, short time or completely cancel the spheroidizing annealing process and they can get qualified bearing steel group. Bearing steel 650 ℃ temperature processing and new technology. If before the eutectoid steel or high carbon steel hot working with fine grained organization or in the process to form a fine grained, in melting temperature range (0.4 ~ 0.6), under a certain strain rate, exhibiting the plastic. U.S. naval institute (NSP) to 650 ℃ temperature of 52100 steel processing test showed that true strain under 650 ℃ 2.5 does not break. Therefore, likely to 650 ℃ temperature processing instead of high temperature processing and combining with spheroidizing annealing process, the simplified equipment and processes, quality is important to save energy and progress. 

Progress in heat treatment, the spheroidizing annealing quality of small, uniform, spherical carbides, and shorten the annealing time or cancel the spheroidizing annealing process have the progress of research, namely the wire rod production by two organizations annealing, after drawing of 720 ℃ ~ 730 ℃ to 760 ℃ of recrystallization annealing annealing.