Method for strengthening treatment of manganese phosphate conversion coating on surface of GCr15 steel bearing

Abstract

The invention provides a GCr15 steel bearing surface manganese phosphate conversion coating strengthening treatment method, which comprises: carrying out degreasing, acetone cleaning, water washing, acid washing, surface adjustment and phosphorization on a GCr15 steel bearing to obtain a phosphorized GCr15 steel bearing, carrying out refining bath treatment, water washing and blow-drying, carrying out oil bath treatment for 5-10 min at a temperature of 20-30 DEG C, carrying out treatment for 10 h at a temperature of 60 DEG C in a nitrogen atmosphere, and naturally cooling to a room temperature to obtain the GCr15 steel bearing surface manganese phosphate conversion coating. The manganese phosphate coating bearing is obtained. According to the method, the fatigue limit of the GCr15 steel bearing is increased, the service life of the GCr15 steel bearing is prolonged, the strengthening treatment efficiency of the bearing is improved, the cost is reduced, and the method is suitable for industrial production and has good application prospects.

Description

Technical Field

[0001] This invention belongs to the field of bearing surface treatment technology, specifically relating to a method for strengthening the surface of GCr15 steel bearings with a manganese phosphate conversion coating. Background Technology

[0002] As a key component of traditional systems, the performance and service life of rolling bearings directly affect the lifespan of the transmission. Therefore, improving the service life of rolling bearings is crucial for extending the transmission's lifespan. In existing rolling bearing systems, fatigue failure remains a significant bottleneck. Rolling bearings are often lubricated with grease to extend their service life. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for strengthening the surface of GCr15 steel bearings with a manganese phosphate conversion coating, which improves the fatigue limit and service life of GCr15 steel bearings, increases the strengthening efficiency of bearings, reduces costs, is suitable for industrial production, and has good application prospects.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for strengthening the surface of GCr15 steel bearings with a manganese phosphate conversion coating, the method being as follows: S1. The GCr15 steel bearing is degreased, cleaned with acetone, washed with water, pickled, surface-conditioned and phosphated to obtain the phosphated GCr15 steel bearing. S2. Under the condition of 60℃, the phosphated GCr15 steel bearing obtained in S1 is subjected to a refining bath treatment for 3 minutes to obtain the refined GCr15 steel bearing. S3. The refined GCr15 steel bearing obtained in S2 is washed with water and dried, then subjected to an oil bath at a temperature of 20℃~30℃ for 5min~10min, and then treated in a nitrogen atmosphere at a temperature of 60℃ for 10h. After naturally cooling to room temperature, a manganese phosphate coated bearing is obtained.

[0005] Preferably, the GCr15 steel bearing in S1 includes GCr15 steel tapered roller bearings and GCr15 steel needle roller bearings.

[0006] Preferably, the degreasing method in S1 is as follows: the GCr15 steel bearing is placed in a weakly alkaline degreasing agent and degreased for 6 minutes at a temperature of 80℃~95℃.

[0007] Preferably, the weakly alkaline degreasing agent is degreasing agent FC-4360.

[0008] Preferably, the acetone cleaning method described in S1 is as follows: ultrasonic cleaning in acetone at a temperature of 20℃~25℃ for 10 minutes.

[0009] Preferably, the water washing method in S1 is: rinsing with clean water at a temperature of 20℃~30℃ for 1min~3min.

[0010] Preferably, the pickling method described in S1 is as follows: pickling with a 20% sulfuric acid aqueous solution for 4 to 5 minutes at a temperature of 50°C to 60°C.

[0011] Preferably, the surface conditioning method described in S1 is as follows: surface conditioning is performed using PL-55 surface conditioner, followed by immersion at 50°C for 2 minutes.

[0012] Preferably, the phosphating method described in S1 is: phosphating in a manganese-based phosphating solution at a temperature of 95°C for 5 min to 15 min.

[0013] Preferably, the specific method of the refining bath treatment in S2 is as follows: the pH of the system is adjusted to 8 by ammonia water to precipitate manganese phosphate.

[0014] Compared with the prior art, the present invention has the following advantages: 1. This invention significantly improves the fatigue limit and service life of GCr15 steel bearings, and also improves the efficiency of bearing strengthening treatment, reduces costs, is suitable for industrial production, and has good application prospects.

[0015] 2. This invention employs a manganese phosphate coating surface strengthening method to strengthen the surface of GCr15 steel bearings. Compared to bearings subjected to conventional martensitic quenching and tempering heat treatment, the manganese phosphate coating strengthening method can significantly improve the anti-friction and wear performance and fatigue life of GCr15 bearings. The difference is that the manganese phosphate coating treatment mainly changes the microstructure of the bearing surface, covering the bearing surface with phosphate compounds, thereby achieving solid and liquid mixed lubrication on the basis of grease lubrication, thus greatly reducing wear and significantly improving fatigue life.

[0016] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. Attached Figure Description

[0017] Figure 1 The images show (a) of a GCr15 steel bearing sample obtained by conventional martensitic quenching and tempering heat treatment in Example 1 of the present invention and (b) of a manganese phosphate coated bearing sample obtained by the strengthening treatment method in Example 1.

[0018] In figure (a), the left image is a disk sample and the right image is a cylindrical sample; in figure (b), the left image is a disk sample and the right image is a cylindrical sample.

[0019] Figure 2 The results are SEM and energy dispersive spectroscopy (EDS) analysis of the surface morphology of the conventionally heat-treated sample after friction and wear tests in Example 1 of this invention; (a) shows the wear morphology of the conventionally heat-treated sample under a 100N load, with a magnified view in the upper right corner; (b) shows the EDS spectrum of region A circled in (a); (c) shows the wear morphology of the conventionally heat-treated sample under a 200N load, with a magnified view in the upper right corner; (d) shows the EDS spectrum of region B circled in (c); (e) shows the wear morphology of the conventionally heat-treated sample under a 300N load, with a magnified view in the upper right corner; and (f) shows the EDS spectrum of region C circled in (e).

[0020] Figure 3 The images show the SEM and energy dispersive spectroscopy (EDS) analysis results of the surface morphology of the manganese phosphate coated bearing sample obtained after friction and wear tests using the manganese phosphate conversion coating strengthening treatment method of Example 1 of the present invention. (a) shows the wear morphology of the manganese phosphate coated bearing sample under a 100N load, with a magnified view in the upper right corner; (b) shows the EDS spectrum of region A circled in (a); (c) shows the wear morphology of the manganese phosphate coated bearing sample under a 200N load, with a magnified view in the upper right corner; (d) shows the EDS spectrum of region B circled in (c); (e) shows the wear morphology of the manganese phosphate coated bearing sample under a 300N load, with a magnified view in the upper right corner; and (f) shows the EDS spectrum of region C circled in (e).

[0021] Figure 4 These are physical images of conventional quenched tapered roller bearings and manganese phosphate coated tapered roller bearings according to Embodiment 1 of the present invention.

[0022] Figure 5 The results are (a) of the number of cycles of conventional quenched tapered roller bearings and manganese phosphate coated tapered roller bearings under normal load conditions and (b) of the number of cycles of conventional quenched tapered roller bearings and manganese phosphate coated tapered roller bearings under high load conditions in Embodiment 1 of the present invention.

[0023] Figure 6 These are physical images of conventional quenched needle roller bearings and manganese phosphate coated needle roller bearings according to Embodiment 1 of the present invention.

[0024] Figure 7 The results show the cycle count of the conventional quenched needle roller bearing and the manganese phosphate coated needle roller bearing of Embodiment 1 of the present invention. Detailed Implementation

[0025] Example 1 According to the material preparation criteria for tapered roller and needle roller bearings, GCr15 steel was selected as the material for specimen preparation. The chemical element composition is shown in Table 1. The heat treatment method is conventional martensitic quenching and tempering, and the hardness is 61HRC.

[0026] The specific method for conventional martensitic quenching and tempering is as follows: after heating to 860℃ and holding at that temperature, oil quenching is performed in KR488 type quenching oil at a temperature of 80℃, a quenching cooling rate of 85℃ / s, a quenching time of 8 minutes, and a quenching stirrer speed of 750rpm, followed by rapid cooling to 110℃; finally, tempering is performed at a low temperature of 150℃ for 120 minutes, followed by air cooling.

[0027] Table 1 Chemical elements of GCr15 steel The method for strengthening the surface of GCr15 steel bearings with manganese phosphate conversion coating in this embodiment is as follows: S1. The GCr15 steel bearing is degreased, cleaned with acetone, washed with water, pickled, surface-conditioned and phosphated to obtain the phosphated GCr15 steel bearing. The degreasing method is as follows: the GCr15 steel bearing is placed in a weak alkaline degreasing agent and degreased for 6 minutes at a temperature of 80°C; the weak alkaline degreasing agent is commercially available and the model is degreasing agent FC-4360; The acetone cleaning method is as follows: ultrasonic cleaning in acetone at a temperature of 25°C for 10 minutes.

[0028] The washing method is as follows: rinse with clean water at a temperature of 30°C for 1 minute; The pickling method is as follows: pickling with a 20% sulfuric acid aqueous solution at a temperature of 50°C for 5 minutes; The surface conditioning method is as follows: use PL-55 surface conditioner to condition the surface and immerse it at 50°C for 2 minutes.

[0029] The phosphating method is as follows: phosphating is performed in a manganese-based phosphating solution at a temperature of 95°C for 5 minutes. The manganese-based phosphating solution is GT-PF-M1A manganese-based phosphating solution, which is commercially available. S2. Under the condition of 60℃, the phosphated GCr15 steel bearing obtained in S1 is subjected to a refining bath treatment for 3 minutes to obtain a refined GCr15 steel bearing; the specific method of the refining bath treatment is: adjusting the pH of the system to 8 by ammonia water to precipitate manganese phosphate. S3. The refined GCr15 steel bearing obtained in S2 is washed with water and dried, then subjected to an oil bath at 30°C for 5 minutes, and then treated at 60°C in a nitrogen atmosphere for 10 hours. After naturally cooling to room temperature, a manganese phosphate coated bearing is obtained.

[0030] In this embodiment, GCr15 steel bearings are used as the material to prepare cylindrical and disc samples. The surface of the samples is strengthened by the manganese phosphate conversion coating method of this embodiment to obtain manganese phosphate coated bearing cylindrical samples. Comparative analysis is performed with GCr15 steel bearing cylindrical samples obtained by conventional martensitic quenching and tempering heat treatment.

[0031] like Figure 1 (a) The disk diagram (left) and cylinder diagram (right) of the GCr15 steel bearing cylindrical sample obtained after conventional martensitic quenching and tempering heat treatment.

[0032] like Figure 1 (b) are the disk diagram (left) and cylinder diagram (right) of the cylindrical sample block of the manganese phosphate coated bearing obtained by the processing method of this embodiment.

[0033] The surface of the GCr15 steel bearing cylindrical sample obtained after manganese phosphate coating strengthening treatment has a dark-colored manganese phosphate conversion film solid lubricant. The surface of the GCr15 steel bearing cylindrical sample obtained after conventional martensitic quenching and tempering heat treatment exhibits its own metallic luster.

[0034] Based on the contact characteristics of tapered roller bearings and needle roller bearings, line contact friction and wear tests were conducted on SRV (Schwing Reib Verschleiss 55), followed by SEM and EDS scanning electron microscopy analysis.

[0035] Figure 1 (b) The manganese phosphate coating of the bearing has a thickness of 6 μm and a surface roughness Ra of about 0.35. The friction and wear test specimen is subjected to strengthening treatment.

[0036] (a) Friction and wear test The standard heat-treated samples were: GCr15 steel discs and cylindrical samples were heated to 860℃ and held at that temperature, then oil-quenched in KR488 quenching oil at a temperature of 80℃, a quenching rate of 85℃ / s, a quenching time of 8 minutes, and a stirring speed of 750 rpm, rapidly cooled to 110℃; finally, they were tempered at 150℃ for 120 minutes and then cooled in air.

[0037] Figure 2The surface morphology of conventionally heat-treated samples after friction and wear tests under loads of 100N, 200N, and 300N is shown in SEM (a, c, e) and energy dispersive spectroscopy (EDS) analysis results (b, d, f).

[0038] from Figure 2 As can be seen from (a) and (c), after the 100N and 200N friction and wear tests, the sample surface still has initial scratches caused by processing, and slight test wear marks can be seen. Figure 2 (e) shows that after the friction and wear test under a load of 300 N, the initial scratches on the sample disappeared, replaced by test scratches left on the sample surface after the friction and wear test. The area outlined in white is the area scanned by EDS analysis, measuring the proportions of elements such as Fe, C, O, P, Mn, and Cr. As the test load gradually increases, the wear on the surface of the metal sample gradually deepens, oxidation occurs inside the metal, and the number of oxygen atoms gradually increases, such as... Figure 2 As shown in (b), (d), and (f).

[0039] Figure 3 The images show the SEM and energy dispersive spectroscopy (EDS) results of the surface morphology of bearing samples with manganese phosphate conversion coating obtained by the GCr15 steel bearing surface strengthening treatment method of this embodiment after friction and wear tests under loads of 100N, 200N, and 300N. The SEM images of the surface morphology are shown below. Figure 3 As shown in (a), 3(c), and 3(e), the energy dispersive spectroscopy (EDS) analysis results are as follows: Figure 3 As shown in (b), 3(d), and 3(f), the SEM results show numerous tiny pits on the sample surface, which can store lubricating oil and facilitate the formation of a lubricating oil film. After the friction test, no significant wear was observed on the sample surface, indicating that the manganese phosphate coating has certain anti-wear properties. Furthermore, along the test trajectory, the coating particles on the sample surface were compacted, indicating that the manganese phosphate coating surface becomes smoother after friction. The white-framed area represents the area scanned by EDS analysis, measuring the proportions of elements such as Fe, C, O, P, Mn, and Cr.

[0040] Figure 3 The energy dispersive spectroscopy (EDS) results (b), (d), and (f) show that there are still certain P, Mn, and O elements on the sample surface, indicating that there is a manganese phosphate coating on the sample substrate surface. Under the test load of 300 N, there was no obvious wear on the sample surface and no coating peeling occurred, indicating that the manganese phosphate coating is well bonded to the substrate and still has good lubrication effect under high load.

[0041] Phosphorus has a certain influence on the microstructure of materials and affects their toughness and hardness. Increasing the phosphorus content can make the contact surface smoother, thereby improving the shear and adhesion properties of alloy steel during friction. Phosphorus can also improve the wear resistance of steel. The pitted structure on the surface of the manganese phosphate coating provides oil storage, continuously supplying lubricant to the contact surfaces of the samples during friction and wear tests, reducing wear between the sample surfaces. Furthermore, the surface coating particles become smoother after running-in, improving surface roughness. Therefore, it can be concluded that the manganese phosphate coated bearing obtained by the method of strengthening the surface of GCr15 steel bearings with manganese phosphate conversion coating in this embodiment has excellent wear resistance and load-bearing capacity, and can improve the fatigue life of the samples.

[0042] (II) Fatigue life test During the test, thermometers and vibration sensors were used to monitor the temperature and vibration values ​​of the outer ring of the test product.

[0043] The vibration sensor is located between the two workstations, and the thermometer monitors the outer ring of the bearing. The temperature control range is ≤95℃, and the maximum test vibration value is twice the initial vibration value. The test equipment will automatically shut down when the monitored temperature or vibration value exceeds the maximum limit.

[0044] 1. Fatigue life test of GCr15 steel tapered roller bearings The experimental parameters of the GCr15 steel tapered roller bearing are shown in Table 2.

[0045] Table 2 Experimental parameters of GCr15 steel tapered roller bearings The quenching method for uncoated reinforced GCr15 steel tapered roller bearings with conventional quenching treatment is as follows: after heating to 860℃ and holding, oil quenching is performed in KR488 quenching oil at a temperature of 80℃, a quenching cooling rate of 85℃ / s, a quenching time of 8 minutes, and a quenching stirrer speed of 750 rpm, followed by rapid cooling to 110℃; finally, tempering is performed at 150℃ for 120 minutes, followed by air cooling.

[0046] Examples of samples of uncoated GCr15 steel tapered roller bearings (conventionally quenched tapered roller bearings) and manganese phosphate coated tapered roller bearings (manganese phosphate coated tapered roller bearings) obtained by the manganese phosphate conversion coating strengthening method of this embodiment are shown in the figures. Figure 4 As shown.

[0047] Conventional hardened tapered roller bearings are shown below. Figure 4 (a) Samples 1 and 2; manganese phosphate coated tapered roller bearings are shown. Figure 4 (b) Sample 1 and Sample 2; The test results are as follows Figure 5 As shown: Under normal load conditions, samples 1 and 2 of the conventionally hardened tapered roller bearings operated for 3.87 × 10⁻⁶ hours respectively. ^ 7 revolutions and 5.82×10 ^ Pitting failure occurred at 7 revolutions. Coated parts 1 and 2 of the manganese phosphate coated tapered roller bearing experienced 3.69 × 10⁻⁶ cycles respectively. ^ 8 revolutions and 3.57×10 ^ Pitting occurred after 8 revolutions. The lifetime result (number of cycles) is as follows: Figure 5 As shown in (a).

[0048] Under high load conditions, samples 1 and 2 of conventionally hardened tapered roller bearings achieved operating times of 5.81 × 10⁻⁶. ^ 6 revolutions and 4.79×10 ^ Pitting failure occurred at 6 revolutions. Coated parts 1 and 2 of the manganese phosphate coated tapered roller bearing underwent 3.15 × 10⁻⁶ cycles respectively. ^ 7 revolutions and 3.71×10 ^ Pitting failure occurred at 7 cycles, and the lifetime result (number of cycles) is as follows: Figure 5 As shown in (b).

[0049] Both products operating under normal and high load conditions met the project targets, with fatigue life of tapered roller bearings increasing by 614% and 542%, respectively.

[0050] 2. Fatigue life test of GCr15 steel needle roller bearings The test parameters for GCr15 steel needle roller bearings are shown in Table 3 below.

[0051] Table 3 Experimental parameters of GCr15 steel needle roller bearings The quenching treatment method for uncoated reinforced GCr15 steel needle roller bearings with conventional quenching treatment is as follows: after heating to 860℃ and holding at that temperature, oil quenching is performed in KR488 quenching oil at a temperature of 80℃, a quenching cooling rate of 85℃ / s, a quenching time of 8 minutes, and a quenching stirrer speed of 750 rpm, followed by rapid cooling to 110℃; finally, tempering is performed at 150℃ for 120 minutes, followed by air cooling.

[0052] The images show the physical examples of uncoated GCr15 steel needle roller bearings that have undergone conventional quenching treatment (conventional quenched needle roller bearings) and manganese phosphate coated needle roller bearings obtained by the manganese phosphate conversion coating strengthening treatment method of this embodiment. Figure 6 As shown.

[0053] Conventional hardened needle roller bearings are shown Figure 6 (a) Manganese phosphate coated needle roller bearings are shown Figure 6 (b); The test results are as follows Figure 7 As shown: Standard quenched needle roller bearing samples 1, 2, and 3 were tested up to 2.63 × 10⁻⁶. ^ 8 revolutions, 2.16 × 10 ^ 8 revolutions and 2.53×10 ^ At 8 revolutions, the testing equipment alarmed and stopped. Inspection of the bearing revealed fatigue spalling of the rolling elements. Coating samples 1 and 2 of the manganese phosphate coated needle roller bearing also showed fatigue spalling at 5.51 × 10⁻⁶ revolutions. ^ 8 revolutions and 5.30×10 ^ At 8 revolutions per minute, the test equipment alarmed and stopped. Inspection of the bearing revealed fatigue spalling of the rolling elements. Based on the combined test data, it was confirmed that the fatigue life of the manganese phosphate coated needle roller bearing was increased by 201%.

[0054] Example 2 The method for strengthening the surface of GCr15 steel bearings with manganese phosphate conversion coating in this embodiment is as follows: S1. The GCr15 steel bearing is degreased, cleaned with acetone, washed with water, pickled, surface-conditioned and phosphated to obtain the phosphated GCr15 steel bearing. The degreasing method is as follows: the GCr15 steel bearing is placed in a weak alkaline degreasing agent and degreased for 6 minutes at a temperature of 95°C; the weak alkaline degreasing agent is commercially available and the model is degreasing agent FC-4360; The acetone cleaning method is as follows: ultrasonic cleaning in acetone at a temperature of 20°C for 10 minutes.

[0055] The washing method is as follows: rinse with clean water at a temperature of 20°C for 3 minutes; The pickling method is as follows: pickling with a 20% sulfuric acid aqueous solution at a temperature of 60°C for 4 minutes; The surface conditioning method is as follows: use PL-55 surface conditioner to condition the surface and immerse it at 50°C for 2 minutes.

[0056] The phosphating method is as follows: phosphating is performed in a manganese-based phosphating solution at a temperature of 95°C for 15 minutes. The manganese-based phosphating solution is GT-PF-M1A manganese-based phosphating solution, which is commercially available. S2. Under the condition of 60℃, the phosphated GCr15 steel bearing obtained in S1 is subjected to a refining bath treatment for 3 minutes to obtain a refined GCr15 steel bearing; the specific method of the refining bath treatment is: adjusting the pH of the system to 8 by ammonia water to precipitate manganese phosphate. S3. The refined GCr15 steel bearing obtained in S2 is washed with water and dried, then subjected to an oil bath at 20°C for 10 minutes, and then treated at 60°C in a nitrogen atmosphere for 10 hours. After naturally cooling to room temperature, a manganese phosphate coated bearing is obtained.

[0057] When the GCr15 steel bearing is a GCr15 steel tapered roller bearing, the fatigue life of the bearing with manganese phosphate coating obtained by the method of strengthening the surface of the GCr15 steel bearing with manganese phosphate conversion coating in this embodiment is increased by 616% and 545% under normal load conditions and high load conditions, respectively.

[0058] When the GCr15 steel bearing is a GCr15 steel needle roller bearing, the fatigue life of the bearing with manganese phosphate coating obtained by the method of strengthening the surface of the GCr15 steel bearing with manganese phosphate conversion coating in this embodiment is increased by 203%.

[0059] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A method for strengthening the surface of GCr15 steel bearings with a manganese phosphate conversion coating, characterized in that, The method is as follows: S1. The GCr15 steel bearing is degreased, cleaned with acetone, washed with water, pickled, surface-conditioned and phosphated to obtain the phosphated GCr15 steel bearing. S2. Under the condition of 60℃, the phosphated GCr15 steel bearing obtained in S1 is subjected to a refining bath treatment for 3 minutes to obtain the refined GCr15 steel bearing. S3. The refined GCr15 steel bearing obtained in S2 is washed with water and dried, then subjected to an oil bath at a temperature of 20℃~30℃ for 5min~10min, and then treated in a nitrogen atmosphere at a temperature of 60℃ for 10h. After naturally cooling to room temperature, a manganese phosphate coated bearing is obtained.

2. The method for strengthening the surface of GCr15 steel bearings with manganese phosphate conversion coating according to claim 1, characterized in that, The GCr15 steel bearings mentioned in S1 include GCr15 steel tapered roller bearings and GCr15 steel needle roller bearings.

3. The method for strengthening the surface of GCr15 steel bearings with manganese phosphate conversion coating according to claim 1, characterized in that, The degreasing method described in S1 is as follows: the GCr15 steel bearing is placed in a weak alkaline degreasing agent and degreased for 6 minutes at a temperature of 80℃~95℃.

4. The method for strengthening the surface of GCr15 steel bearings with manganese phosphate conversion coating according to claim 3, characterized in that, The weakly alkaline degreasing agent is designated as degreasing agent FC-4360.

5. The method for strengthening the surface of GCr15 steel bearings with manganese phosphate conversion coating according to claim 1, characterized in that, The acetone cleaning method described in S1 is as follows: ultrasonic cleaning in acetone at a temperature of 20℃~25℃ for 10 minutes.

6. The method for strengthening the surface of GCr15 steel bearings with manganese phosphate conversion coating according to claim 1, characterized in that, The water washing method described in S1 is as follows: rinse with clean water at a temperature of 20℃~30℃ for 1min~3min.

7. The method for strengthening the surface of GCr15 steel bearings with manganese phosphate conversion coating according to claim 1, characterized in that, The pickling method described in S1 is as follows: pickling with a 20% sulfuric acid aqueous solution for 4 to 5 minutes at a temperature of 50℃ to 60℃.

8. The method for strengthening the surface of GCr15 steel bearings with manganese phosphate conversion coating according to claim 1, characterized in that, The surface conditioning method described in S1 is as follows: use PL-55 surface conditioner for surface conditioning and immerse in it at 50°C for 2 minutes.

9. The method for strengthening the surface of GCr15 steel bearings with manganese phosphate conversion coating according to claim 1, characterized in that, The phosphating method described in S1 is as follows: phosphating in a manganese-based phosphating solution at a temperature of 95°C for 5 to 15 minutes.

10. The method for strengthening the surface of GCr15 steel bearings with manganese phosphate conversion coating according to claim 1, characterized in that, The specific method of refining bath treatment described in S2 is as follows: the pH of the system is adjusted to 8 by ammonia water, and manganese phosphate precipitate is formed.

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