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Bearing Hardness Uniformity, Wear Resistance
Aug 15, 2017

If the heat treatment is not properly, the bearing heat treatment is one of the core key processes of the bearing manufacturer. The heat treatment process and the physical properties of the raw materials determine the final hardness, hardness uniformity, abrasion resistance and contact fatigue life of the bearing. What will happen?

Bearing parts in the heat treatment, there is thermal stress and tissue stress, this internal stress can be superimposed or partially offset, is complex and varied, because it can with the heating temperature, heating speed, cooling, cooling speed, part shape And the size of the change, so heat treatment deformation is inevitable. Knowing and mastering the law of change can make the deformation of the bearing parts (such as the ring of the ellipse, the size of large, etc.) placed in a controlled range, is conducive to the production of the. Of course, the mechanical collision during the heat treatment also causes the part to be deformed, but this deformation can be reduced and avoided by improved operation.

Precipitation of the microstructure after quenching can be observed from the rough parts of the bearing parts. But to determine the extent of its overheating must observe the microstructure. If the coarse needle-like martensite appears in the quenched tissue of GCr15 steel, it is quenched and superheated. The formation of the reasons may be quenching heating temperature is too high or heating and holding time is too long caused by a comprehensive overheating; may also be due to the original organization of ribbon carbide serious, in the low band between the two areas of the formation of local martensite needle- Caused by local overheating. In the superheated tissue, the retained austenite increases and the dimensional stability decreases. As the quenching of the organization overheating, steel crystal is large, will lead to the decline in the toughness of parts, impact resistance, bearing life is also reduced.

Bearing parts in the quenching process due to the formation of internal cracks caused by cracks, said quenching crack. The reason for this crack is due to the fact that the hardening temperature is too high or the cooling is too fast. The stress of the thermal stress and the mass change of the metal mass is larger than that of the steel. The original defects of the working surface (such as surface micro- (Such as slag, severe non-metallic inclusions, white spots, shrinkage, etc.) in the quenching of the formation of stress concentration; severe surface decarburization and carbide segregation; parts quenched after tempering Or not timely tempering; the previous process caused by the cold punch stress is too large, forging folding, deep turning knife marks, oil groove sharp edges and corners.

  The bearing is an important mechanical foundation connection, widely used in the mechanical industry. It can be said that there is rotation where there is bearing. Automobile as a modern society, the main means of transport, the automobile industry has become China's main pillar industry, which also plays an important role in the bearing. Many of the car security parts, such as steering gear, engine and gearbox, etc., can see the bearing figure. Automotive bearings as a branch of the bearing, bearing, impact and high-speed rotation and other special properties, the performance of passengers, drivers and the safety of the vehicle itself has an important impact.

Heat treatment as a key process in the manufacturing process of automotive bearings, the quality of its processing and raw materials is the impact of bearing life of the two important factors. In the following, the author based on their own work experience and knowledge, from the automotive bearing materials, heat treatment design, heat treatment process, heat treatment equipment, heat treatment technology and heat treatment development direction, the automotive bearing heat treatment technology to do a brief exposition.