Common materials for bearing inner and outer rings
The inner and outer rings and rolling parts of rolling bearings should have high hardness and contact fatigue strength, good wear resistance and impact toughness, generally made of chrome-manganese high carbon steel (pitting resistance), commonly used materials are GCr15 bearing steel, GCr15SiMn bearing steel, GCr6 bearing steel, GCr9 bearing steel, etc. The hardness after quenching is not less than 61HRC-65HRC.
GCr15 bearing steel
GCr15 bearing steel is a kind of high carbon chromium bearing steel with less alloy content, good performance and the most widely used. After quenching and tempering, it has high and uniform hardness, good wear resistance and high contact fatigue performance. The cold working plasticity of the steel is medium, the cutting performance is general, the welding performance is poor, the sensitivity to the formation of white spots is large, there is temper brittleness. GCr15 bearing steel, including c0.95-1.05, Mn0.25-0.45, Si0.15-0.35.
Good overall performance. Good cutting performance after spheroidizing annealing. High hardness and uniformity after quenching and tempering, high wear resistance and contact fatigue strength. Good thermal processing performance. Contains less alloying elements, the price is cheaper.
GCr15SiMn bearing steel
GCr15SiMn bearing steel has higher wear resistance and hardenability than GCr15, medium plastic deformation in cold processing, poor weldability, sensitivity to white spots, and temper brittleness in heat treatment. Used for making rings with wall thickness >12mm and outer diameter ≥250mm; Steel ball with diameter 50.8-203.2, roller with diameter >22mm; In addition, it can also be used for other mechanical parts requiring high hardness and high wear resistance, such as rolls. Screw gauge, etc.
GCr15SiMn steel is a high-carbon, high-chromium bearing steel with higher wear resistance and hardenability than GCr15 steel. The critical quenching diameter in the oil is 90~110mm (the volume fraction is 50% martensite), after the oil cold quenching of 840°C, the tempering state of 350°C, and then the light quenching, the surface hardness is as high as 1096HV, and the depth of the hardened layer can reach 1mm. In view of the shortcomings of heat treatment process of forming roller, non-martensitic transformation is produced by precooling at thin edge to generate totensite or sortensite, which can enhance toughness, reduce stress, and then quench as a whole to meet the process requirements.
Cold treatment can improve the dimensional stability of bearings, or martensite grading quenching to stabilize residual austenite, obtain high dimensional stability and high toughness. This steel is generally not recommended for forging. Generally used after quenching and low temperature tempering.
GCr6 bearing steel
GCr6 bearing steel measuring tool cutting tool steel, this steel composition and GCr6 bearing steel, its hardenability, hardness and wear resistance are higher than carbon tool steel, heat treatment size change is not large. Widely used as measuring tools, such as template, plate, sample sleeve, gauge, block gauge, ring gauge, thread plug gauge and sample column, etc., can also be used in the manufacture of wire drawing die and cold heading die and other cold working die, as well as low speed tool cutting not too hard material.
GCr9 bearing steel
Higher wear resistance and hardenability than GCr6 steel, machinability is acceptable, cold strain plasticity is medium, poor weldability, white spot formation is also more sensitive, heat treatment has a tempering brittleness tendency. For the manufacture of steel balls with a diameter of 13.5-25.4mm, tapered rollers with a diameter of 10.3-18.5mm, cylindrical rollers with a diameter of 9.4-17.2 and spherical rollers with a diameter of 9.2-17.1.
GCr9 steel is a kind of high carbon chromium bearing steel with less alloy content, good performance and the most widely used. After quenching and tempering, it has high hardness, uniform structure, good wear resistance and high contact fatigue performance. The cold working plasticity of the steel is medium, the cutting performance is general, the welding performance is poor, the sensitivity to the formation of white spots is large, there is temper brittleness.
Mainly used in the production of internal combustion engines, electric locomotives, automobiles, tractors, machine tools, rolling machines, drilling machines, mining machinery, general machinery, as well as high-speed rotation of high load mechanical transmission bearings of steel balls, rollers and rings. In addition to making balls, bearing rings, etc., it is sometimes used to make tools, such as punching dies and measuring tools.