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The current high carbon chromium bearing steel national standard GB / T18254-2002 included in the steel a total of five, of which three grades of bearing steel GCr15SiMn, GCr15SiMo and GCr18Mo is a high hardenability of steel. GCr15SiMn steel application time is longer, it is based on the GCr15 steel, the appropriate increase in Si, Mn content of improved steel to improve its hardenability and elastic limit, wear resistance than GCr15 steel, but the cutting performance Slightly less than GCr15 steel, there is a tendency to temper brittleness, mainly for the manufacture of wall thickness greater than 12mm, diameter greater than 250mm bearing rings, and ball diameter greater than 50mm, cone, cylindrical and spherical roller diameter greater than 22mm bearing parts The
GCr15SiMo and GCr18Mo steel were developed from 1986 to 1995, the high hardenability of bearing steel, the purpose is to adapt to the development of the national economy, especially heavy machinery, mining machinery, mining and drilling machinery, large-scale, heavy Development needs. These areas of large bearings of the variety, specifications and quantity of the demand for more and more bearing size increases, requiring the bearing inside and outside the ring of the effective wall thickness and roll diameter also increases, with GCr15SiMn steel hardenability, quenching Hard and bearing life can not meet the actual needs.
The basic idea of GCr15SiMo steel development is that the effect of Si on the properties of Cr-Si-based GCr15SiMn steel of Cr-Mo series SKF25 and Mo is studied, and the hardenability J60≥25mm and the hardenability Good performance of the steel; GCr18Mo steel is based on the German steel 100CrMo7 (equivalent to SKF24) and the development of suitable for bainite isothermal quenching of steel, the hardenability of 880 end quenching J60 value of 18mm. Since the development of three kinds of steel and since the standard, GCr15SiMn and GCr18Mo larger, GCr15SiMn steel is used to manufacture large bearings. GCr18Mo steel for bainite isothermal quenching treatment, a large number of applications in the railway passenger car bearings. The GCr15SiMo steel is currently less used, for many reasons, such as the use of habits, material prices, more importantly, and bearing manufacturers and bearing users of its technology and performance is not very clear about. In order to rationally and effectively choose to use these three materials, the researchers of their main process and performance of a comprehensive experimental study and comparative analysis.
Test materials to choose a different melting furnace number, and different specifications of the GCr15SiMn, GCr15SiMo and GCr18Mo hot-rolled annealing bar. Three kinds of steel are electric furnace + vacuum degassing method of smelting, chemical composition and metallurgical quality in line with GB / T18254-2002 standard. The hardenability of the three materials was compared by the top quenching test. The relationship between the quenching temperature and the hardness of the three kinds of steel was studied. The effects of the toughness and fracture toughness of the three kinds of steel under different heat treatment were studied. The contact fatigue life of TLP samples of GCr15SiMn steel and GCr15SiMo steel was studied. The contact fatigue life of TLP samples of GCr15SiMo steel under the bainite and M / B composite structure was investigated. The
Research indicates:
From the three kinds of bearing steel hardenability comparison shows that GCr15SiMo steel best, GCr15SiMn steel and GCr18Mo steel slightly worse, and the two are similar. Therefore, in the case of high hardenability and effective wall thickness (or diameter) increase in the martensitic quenching, you can give priority to the use of GCr15SiMo steel, followed by GCr15SiMn steel. GCr18Mo steel is used for lower bainite isothermal quenching treatment.
From the three kinds of bearing steel hardenability comparison shows that GCr15SiMo steel is best, GCr15SiMo steel 65 ~ 80 square samples can be hardened, and GCr15SiMn steel and GCr15SiMo steel is much different.
GCr15SiMo steel is superior to GCr15SiMn steel and GCr18Mo steel.
The impact toughness and fracture toughness of GCr15SiMn steel and GCr15SiMo steel were similar to that of GCr15SiMo steel and GCr15SiMn steel. The impact toughness and fracture toughness of GCr18Mi steel and GCr15SiMo steel were similar to that of GCr15SiMo steel.
Under the condition of conventional martensitic quenching and tempering, the contact fatigue life of GCr15SiMo steel is higher than that of GCr15SiMn steel. The fatigue life of the whole bainite (BL) structure is higher than that of the M / B composite structure under isothermal quenching of GCr15SiMo steel and GCr18Mo steel.
Bearings used under high impact load, preferred to choose GCr18Mo steel isothermal bainite quenching, in the smaller impact load, can also be used GCr15SiMo steel isothermal bainite quenching.


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