Keywords: bearings, material, materials for bearing, bearing inner and outer rings, rolling bearings, spherical rollers, cylindrical rollers, rolling machines, bearing steel
The inner and outer rings and rolling body of rolling bearings should have high hardness and contact fatigue strength, good wear resistance and impact toughness. They are generally made of chromium-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 shall not be lower 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 is the most widely used. After quenching and tempering, it has a 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, welding performance is poor, the formation of white spot sensitive performance, temper brittleness. GCr15 bearing steel, containing C0.95-1.05, Mn0.25-0.45, SI0.15-0.35.
Good overall performance. Spheroidizing annealing has good machinability. After quenching and tempering, the hardness is high and uniform, wear resistance and contact fatigue strength is high. It has good thermal workability, fewer alloying elements and a cheaper price.
GCr15SiMn bearing steel
GCr15SiMn bearing steel has higher wear resistance and hardenability than GCr15, moderate cold working plastic deformation, poor weldability, sensitivity to the formation of white spots, and temper brittleness when heat treatment. For the manufacture of wall thickness >12mm, outer diameter ≥250mm rings; 50.8-203.2 diameter of steel ball, diameter >22mm roller; In addition, it can also be used for other mechanical parts requiring high hardness and wear resistance, such as rolls. Screw gauges, etc.
GCr15SiMn steel is a high carbon, high chromium bearing steel than GCr15 steel has higher wear resistance and hardenability. The critical quenching diameter in oil is 90~110mm (volume fraction of 50% martensite), after the oil cold quenching at 840°C, tempered at 350°C, and then light quenching, the surface hardness is up to 1096HV, and the depth of hardened layer is up to 1mm. In view of the deficiency of heat treatment process of forming roller, the thin edge precooling is used to produce non-martensite transformation, resulting in trostenite or sotenite, and then the toughness is enhanced, the stress is reduced, and the whole quenching can meet the process requirements.
Cold treatment can improve the dimensional stability of bearings, or martensite step quenching to stabilize the residual austenite, to obtain high dimensional stability and high toughness. Forging this steel is generally not recommended. Generally used after quenching and low-temperature tempering.
GCr6 bearing steel
GCr6 bearing steel is used for measuring and cutting tools. The composition of this steel is similar to GCr6 bearing steel. Its hardenability, hardness and wear resistance are higher than carbon tool steel. It is widely used for measuring tools, such as sample plate, clamp plate, sample sleeve, gauge, block gauge, ring gauge, thread plug gauge and sample column, etc. It can also be used for making cold work die such as drawing die and cold heading die, as well as low-speed cutting tools for less hard materials.
GCr9 bearing steel
Wear resistance and hardenability are higher than GCr6 steel, machinability is ok, cold strain plasticity is medium, weldability is poor, the formation of white spot is also more sensitive, heat treatment tempering brittle tendency. Used for manufacturing steel balls 13.5-25.4mm in diameter, tapered rollers 10.3-18.5mm in diameter, cylindrical rollers 9.4-17.2 in diameter and spherical rollers 9.2-17.1 in diameter.
GCr9 steel is a kind of high carbon chromium bearing steel with less alloy content, good performance and is 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, welding performance is poor, the formation of white spot sensitive performance, 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 rotating high load mechanical transmission bearing ball, roller and ring. In addition to making balls, bearing rings, etc., sometimes also used to make tools, such as punching die, measuring tools.
