Vacuum Heat Treatment Process Parameters of Bearing Steel

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Bearing steels such as GCr15, GCrI15SiMn, etc. are used to make bearing rings, balls (columns), tools and molds, etc., with hardness ≥60HRC and deformation in compliance with the requirements.

Bearing steel as a high-carbon and high-chromium steel, its high carbon content is mainly to ensure that the steel has high hardness and wear resistance. In the actual production process, vacuum heat-treated bearing steel is used for high manufacturing precision, small heat treatment distortion, and hardness. Miniature bearings and high-precision bearings that are difficult to be processed evenly and after heat treatment, vane stators in hydraulic components made of bearing steel, plungers in plunger pumps, and other precision parts and molds, etc., can be improved by vacuum heat treatment. The wear resistance and contact fatigue life of the bearing steel are more than 2 times, so that the hydraulic coupling parts, precision parts, and molds made of bearing steel will not be oxidized, decarburized and corroded, and significantly reduce the distortion after heat treatment. The vacuum heat treatment process specifications of commonly used bearing steels are shown in Table 1.

Steel number	Quenching		Temper		Hardness /HRC
	Temperature/℃	Vacuum/℃	Temperature/℃	Time/H
GCr15	Warm up 520~ 580 Heating 830~ 850	10– 3 10-2~ 10– 3	150~160	2-3	≥60
GCr15SiMn	Warm up 520~ 580 Heating 820~ 840	10-2~  10– 3 10-1~  10-2	150~160	2-3	≥60
GSiMnV(RE)	Warm up 500~ 550 Heating 780~ 810	10-2~  10– 3 10-1~  10-2	150~170	2-3	≥62
GCrSiMnMoV(RE)	Warm up 500~ 550 Heating 770~ 810	10-2~  10– 3 10-1~  10-2	150~170	2-3	≥64

Table 1 Vacuum heat treatment process specification of commonly used bearing steel

The quenching temperature in the table should be selected according to the actual situation. When the size of the part is small, the lower limit of the specified temperature should be used. When the section size is larger, the upper limit of the temperature should be used. The deformation is small during spheronization, the degree of carbide fragmentation is poor, the particle size is slightly coarser and not uniform, and the quenching heating temperature is higher than the upper limit, which is conducive to the dissolution of the carbide. The choice of vacuum degree is based on whether the steel contains alloy elements with higher vapor pressure. If the content of Mn in steel is high, a lower vacuum degree (13. 3Pa) should be selected during quenching and heating. Bearings made of bearing steel Or parts require higher hardness after heat treatment, so low temperature tempering treatment can be carried out in ordinary low temperature nitrate furnace, oil furnace or circulating air electric furnace. For bearings or parts that have strict requirements for dimensional stability and bearings that work at low temperatures, they are subjected to cold treatment immediately after vacuum quenching, and the time is 1 to 2 hours.

Shanghai Geheng Vacuum Technology Co., Ltd. is a vacuum heat treatment furnace manufacturer with many years of experience in design, manufacturing and production. Mainly produce vacuum heat treatment furnace, vacuum sintering furnace, vacuum brazing furnace, New Energy And Environmental Protection Equipment and other vacuum equipments.Provide customized services, equipment work area can be based on customer output.

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