6Cr13Mo stainless steel bearing retained austenite heat treatment method

Abstract

A 6Cr13Mo stainless steel bearing retained austenite heat treatment method comprises the following steps that a bearing ring material is put into a vacuum quenching furnace, and the vacuum quenching furnace is gradually heated for quenching; cooling the quenched bearing ring material in a vacuum quenching furnace; the cooled bearing ring material is put into a tempering furnace to be tempered; taking out the tempered bearing ring material, immediately putting the bearing ring material into cryogenic equipment, cooling the bearing ring material from 0 DEG C to-150 DEG C, and freezing the bearing ring material; and taking out the frozen bearing ring material, putting the bearing ring material into the tempering furnace again for tempering, cooling to room temperature, and taking out the bearing ring material. Compared with a common quenching and tempering process, the 6Cr13Mo stainless steel bearing subjected to heat treatment by adopting the method has the advantages that the content of retained austenite of the bearing is greatly reduced on the premise that the hardness is basically kept unchanged, so that the rigidity of the bearing is improved.

Description

Technical Field

[0001] The invention relates to the technical field of bearing heat treatment, and in particular to a method for heat treatment of retained austenite of a 6Cr13Mo stainless steel bearing. Background Art

[0002] Existing bearings generally use bearing steel, which has excellent wear resistance. The manufactured bearings have long service life and low noise. However, under some special working conditions, bearing steel bearings are prone to rust, such as kitchen equipment, medical equipment, etc. Therefore, stainless steel is used to manufacture bearings. Stainless steel bearings have advantages over bearing steel bearings in temperature resistance and corrosion resistance, but rigidity issues also affect stainless steel bearings. Compared with bearing steel bearings, stainless steel bearings have a high alloy content and the residual austenite content is more difficult to control. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a method for heat treatment of retained austenite in 6Cr13Mo stainless steel bearings in view of the deficiencies of the above-mentioned prior art.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] A method for heat treating retained austenite of a 6Cr13Mo stainless steel bearing comprises the following steps:

[0006] Step 1: Place the bearing ring material into a vacuum quenching furnace, and gradually heat up the vacuum quenching furnace for quenching;

[0007] Step 2: The quenched bearing ring material is cooled in a vacuum quenching furnace;

[0008] Step 3: The cooled bearing ring material is placed in a tempering furnace for tempering;

[0009] Step 4: Take out the tempered bearing ring material and immediately put it into the deep freezing equipment, cool it from 0℃ to -150℃ for freezing treatment;

[0010] Step 5: Take out the frozen bearing ring material and put it into the tempering furnace again for tempering, then cool it to room temperature and take it out.

[0011] Furthermore, in step 1, the vacuum quenching furnace is heated from room temperature to 630-660°C within 9 minutes, kept warm for 30 minutes, then heated to 840-860°C within 40 minutes, kept warm for 90 minutes, and then heated to 1000-1050°C within 30 minutes, and kept warm for 90 minutes.

[0012] Furthermore, in step 2, 10 MPa nitrogen is kept flowing into the vacuum quenching furnace for cooling, and the temperature is cooled to 60-100° C. within 10 minutes.

[0013] Furthermore, the bearing ring material in step 3 is placed in a tempering furnace at 100-130° C. for 30 minutes.

[0014] Furthermore, in step 4, the deep cooling equipment is cooled to 0°C and kept warm for 5 minutes, then cooled to -50°C and kept warm for 30 minutes, and then cooled to -150°C and kept warm for 2 hours.

[0015] Furthermore, in step 5, the bearing ring material is placed in a furnace and kept warm at 160° C. to 190° C. for 4 hours.

[0016] Furthermore, in step 4, the deep cooling equipment is a freezing furnace.

[0017] Compared with the prior art, the present invention provides a method for heat treating retained austenite of a 6Cr13Mo stainless steel bearing. Compared with ordinary quenching and tempering processes, the 6Cr13Mo stainless steel bearing heat treated by the method greatly reduces the retained austenite content of the bearing while keeping the hardness basically unchanged, thereby improving the rigidity of the bearing. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present invention will be described clearly and completely below.

[0019] Example 1

[0020] Take S830 bearing as an example

[0021] The bearing ring material is placed in a vacuum quenching furnace, and the temperature is raised from room temperature to 630°C within 9 minutes, and kept warm for 30 minutes. Then, the temperature is raised to 840°C within 40 minutes, and kept warm for 90 minutes. Then, the temperature is raised to 1000°C within 30 minutes, and kept warm for 90 minutes. Then, 10MPa nitrogen is kept passing through the vacuum quenching furnace for cooling. It is cooled to 70°C within 10 minutes. The bearing ring material is then placed in a tempering furnace and kept warm at 110°C for 30 minutes. The tempered bearing ring material is taken out and immediately placed in a freezing furnace, cooled to 0°C and kept warm for 5 minutes, then reduced to -50°C and kept warm for 30 minutes, and then continued to be reduced to -150°C and kept warm for 2 hours. Then, the frozen bearing ring material is taken out and placed in the tempering furnace again for tempering, kept warm at 160°C for 4 hours, cooled to room temperature and taken out.

[0022] Example 2

[0023] Take SMR105 bearing as an example

[0024] The bearing ring material is placed in a vacuum quenching furnace, and the temperature is raised from room temperature to 650°C within 9 minutes, and kept warm for 30 minutes. Then, the temperature is raised to 850°C within 40 minutes, and kept warm for 90 minutes. Then, the temperature is raised to 1030°C within 30 minutes, and kept warm for 90 minutes. Then, 10MPa nitrogen is kept passing through the vacuum quenching furnace for cooling. It is cooled to 80°C within 10 minutes. The bearing ring material is then placed in a tempering furnace and kept warm at 120°C for 30 minutes. The tempered bearing ring material is taken out and immediately placed in a freezing furnace, cooled to 0°C and kept warm for 5 minutes, then cooled to -50°C and kept warm for 30 minutes, and then continued to be cooled to -150°C and kept warm for 2 hours. Then, the frozen bearing ring material is taken out and placed in the tempering furnace again for tempering, kept warm at 180°C for 4 hours, cooled to room temperature and taken out.

[0025] Example 3

[0026] Take SR144 bearing as an example

[0027] The bearing ring material is placed in a vacuum quenching furnace, and the temperature is raised from room temperature to 660°C within 9 minutes, and kept warm for 30 minutes. Then, the temperature is raised to 860°C within 40 minutes, and kept warm for 90 minutes. Then, the temperature is raised to 1050°C within 30 minutes, and kept warm for 90 minutes. Then, 10MPa nitrogen is kept passing through the vacuum quenching furnace for cooling. It is cooled to 90°C within 10 minutes. Then, the bearing ring material is placed in a tempering furnace and kept warm at 130°C for 30 minutes. The tempered bearing ring material is taken out and immediately placed in a freezing furnace, cooled to 0°C and kept warm for 5 minutes, then reduced to -50°C and kept warm for 30 minutes, and then continued to be reduced to -150°C and kept warm for 2 hours. Then, the frozen bearing ring material is taken out and placed in the tempering furnace again for tempering, kept warm at 190°C for 4 hours, cooled to room temperature and taken out.

[0028] Comparative Example

[0029] Take SMR105 bearing as an example

[0030] The bearing ring material is placed in a vacuum quenching furnace, and the temperature is raised from room temperature to 780°C within 30 minutes, and kept warm for 55 minutes. Then, the temperature is raised to 1040°C within 30 minutes, and kept warm for 60 minutes. Then, it is quickly cooled to 70°C by immersion in oil within 15 minutes. It is taken out of the vacuum quenching furnace and cooled to room temperature. It is placed in a freezing furnace, cooled to -80°C and kept warm for 30 minutes. Then, the frozen bearing ring material is taken out and placed in a tempering furnace for tempering. It is kept warm at 170°C for 90 minutes and then taken out.

[0031] The treated bearing rings were tested by X-ray diffractometer (XRD) with test parameters of 45°-115°, step length of 0.03°, and 1S per step. XRD scanning curve data were obtained and the Paralympic percentage was obtained after processing and calculation, as shown in Table 1 below.

[0032] Table 1

[0033]

[0034] It can be seen that the residual content of 6Cr13Mo stainless steel bearings made by this method is reduced.

[0035] The present invention is not limited to the described embodiments. Those skilled in the art may make some modifications or changes without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined in the claims.

Claims

1. A method for heat treatment of retained austenite of 6Cr13Mo stainless steel bearings, characterized in that: The following steps are included: Step 1: Place the bearing ring material into a vacuum quenching furnace, and gradually heat up the vacuum quenching furnace for quenching; Step 2: The quenched bearing ring material is cooled in a vacuum quenching furnace; Step 3: The cooled bearing ring material is placed in a tempering furnace for tempering; Step 4: Take out the tempered bearing ring material and immediately put it into the deep freezing equipment, cool it from 0℃ to -150℃ for freezing treatment; Step 5: Take out the frozen bearing ring material and put it into the tempering furnace again for tempering, then cool it to room temperature and take it out.

2. A 6Cr13Mo stainless steel bearing retained austenite heat treatment method according to claim 1, characterized in that: In step 1, the vacuum quenching furnace is heated from room temperature to 630-660°C within 9 minutes, kept warm for 30 minutes, then heated to 840-860°C within 40 minutes, kept warm for 90 minutes, and then heated to 1000-1050°C within 30 minutes, and kept warm for 90 minutes.

3. A 6Cr13Mo stainless steel bearing retained austenite heat treatment method according to claim 1, characterized in that: In step 2, 10 MPa nitrogen is kept flowing into the vacuum quenching furnace for cooling, and the temperature is cooled to 60-100° C. within 10 minutes.

4. A 6Cr13Mo stainless steel bearing retained austenite heat treatment method according to claim 1, characterized in that: In step 3, the bearing ring material is placed in a tempering furnace at 100-130°C for 30 minutes.

5. The method for heat treatment of retained austenite of 6Cr13Mo stainless steel bearing according to claim 1, characterized in that: In step 4, the deep cooling equipment is cooled to 0°C and kept warm for 5 minutes, then cooled to -50°C and kept warm for 30 minutes, and then cooled to -150°C and kept warm for 2 hours.

6. A method for heat treatment of retained austenite of 6Cr13Mo stainless steel bearing according to claim 1, characterized in that: In step 5, the bearing ring material is placed in a furnace and kept warm at 160°C to 190°C for 4 hours.

7. The method for heat treatment of retained austenite of 6Cr13Mo stainless steel bearing according to claim 1, characterized in that: In step 4, the deep cooling equipment adopts a freezing furnace.

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