Bearing steel spheroidizing annealing technology

Abstract

The invention discloses a bearing steel spheroidizing annealing technology which comprises the following steps: cleaning bearing steel in a modified maleopimaric acid lauramide sodium dicarboxylate solution, taking out the bearing steel, washing the bearing steel with water, and drying the bearing steel to obtain the cleaned bearing steel; the method comprises the following steps: heating the cleaned bearing steel to 900-1100 DEG C for the first time in an electric pulse manner, preserving heat, cooling to 600-700 DEG C, preserving heat, cooling to room temperature, heating to 650-750 DEG C for the second time, preserving heat, cooling to 500-700 DEG C, cooling to room temperature, heating to 800-900 DEG C for the third time, preserving heat, cooling to room temperature, heating to 120-200 DEG C for the fourth time, preserving heat, cooling to room temperature, and cooling to room temperature. And annealing to obtain the annealed bearing steel. The method is used for solving the technical problem that the bearing steel after spheroidizing annealing is unstable in quality.

Description

Technical Field

[0001] The invention belongs to the technical field of bearing steel production, and in particular relates to a bearing steel spheroidizing annealing technology. Background Art

[0002] Bearing steel is steel used to manufacture balls, rollers and bearing rings. It is mainly concentrated in the parts of various rolling bearings and is widely used in large equipment such as metallurgical equipment, precision machinery and high-speed trains. The quality of bearing steel is a key factor in determining the quality of bearings. High-quality bearing steel has excellent resistance to plastic deformation, friction and wear, heat shock resistance, strong reliability, and long service life. It is an important guarantee for bearings to operate for a long time in harsh working environments with complex stress states and high stress values. In recent years, the output of bearing steel in my country has increased year by year, which further highlights the importance of bearing steel in the modern industrial system.

[0003] Bearing steel, also known as high-carbon chromium steel, requires a long period of spheroidizing annealing during the processing and preparation process to soften the material, reduce deformation resistance, and prevent quenching cracking and deformation. The purity and uniformity of bearing steel are important factors affecting the life of bearings. The existing spheroidizing annealing process generally requires a long annealing time, and the quality of bearing steel after spheroidizing annealing is also unstable. Summary of the invention

[0004] The invention provides a bearing steel spheroidizing annealing technology for solving the technical problem of unstable quality of bearing steel after spheroidizing annealing.

[0005] In view of this, the present invention provides a bearing steel spheroidizing annealing technology, which is characterized by comprising the following steps:

[0006] S1: Wash the bearing steel in a modified sodium maleopimaric acid dodecylamide dicarboxylate solution.

[0007] Take out, wash with water, and dry to obtain cleaned bearing steel;

[0008] S2: The cleaned bearing steel is heated to 900-1100°C for the first time by electric pulse, kept warm, first cooled to 600-700°C, kept warm, and then cooled to room temperature, heated to 650-750°C for the second time, kept warm, first cooled to 500-700°C, and then cooled to room temperature, heated to 800-900°C for the third time, kept warm, and cooled to room temperature, heated to 120-200°C for the fourth time, kept warm, and cooled to room temperature to obtain annealed bearing steel.

[0009] Furthermore, a bearing steel spheroidizing annealing technology comprises the following steps:

[0010] S1: washing the bearing steel in a modified sodium maleopimaric acid dodecylamide dicarboxylate solution, taking out, washing with water, and drying to obtain the washed bearing steel;

[0011] S2: The cleaned bearing steel is heated to 900-1100°C for the first time by electric pulse, kept at this temperature for 20-40min, cooled to 600-700°C, kept at this temperature for 20-40min, heated to 650-750°C for the second time, kept at this temperature for 1-3h, cooled to 500-700°C first, and then cooled to room temperature, heated to 800-900°C for the third time, kept at this temperature for 10-20min, cooled to room temperature, heated to 120-200°C for the fourth time, kept at this temperature for 1-3h, and cooled to room temperature to obtain annealed bearing steel;

[0012] Wherein, the mass fraction of the modified sodium maleopimaric acid dodecanamide dicarboxylate solution in step S1 is 30-50%.

[0013] Optionally, the modified maleopimaric acid sodium dodecanamide dicarboxylate is prepared by the following method:

[0014] Put modified maleopimaric acid, dodecylamine and ethylenediamine into an ethanol solution, mix well, and react to obtain a mixed solution A;

[0015] Put sodium hydroxide into the ethanol solution and mix well to obtain a mixed solution B;

[0016] The mixed solution A is added to the mixed solution B, and the mixture is heated and stirred continuously to react. After the reaction is completed, the mixture is cooled and filtered, and the filtrate is collected and concentrated under reduced pressure to obtain modified sodium maleopimaric acid dodecanamide dicarboxylate.

[0017] Furthermore, the modified maleopimaric acid sodium dodecanamide dicarboxylate is prepared by the following method:

[0018] Place modified maleopimaric acid, dodecylamine and ethylenediamine into an ethanol solution, mix well, and react for 4-6 hours to obtain a mixed solution A;

[0019] Put sodium hydroxide into the ethanol solution and mix well to obtain a mixed solution B;

[0020] Add mixed solution A to mixed solution B, heat to 40-60°C, stir continuously, react for 4-6h, and after the reaction is completed, cool to room temperature, filter, collect the filtrate, and concentrate under reduced pressure to obtain modified maleopimaric acid dodecanamide dicarboxylate sodium;

[0021] The weight ratio of modified maleopimaric acid to ethylenediamine is 1:(0.01-0.03), the amount of ethanol solution added to each gram of modified maleopimaric acid is 6-8 mL, the amount of ethanol solution added to each gram of sodium hydroxide is 4-6 mL, and the mass fraction of the ethanol solution is 50%.

[0022] Optionally, the weight ratio of the modified maleopimaric acid, dodecylamine and sodium hydroxide is 1:

[0023] (0.5-0.9):(0.2-0.4).

[0024] Optionally, the modified maleopimaric acid is prepared by the following method:

[0025] The rosin and dehydrated malic anhydride are uniformly mixed, heated, reacted, cooled, washed, and dried to obtain maleopimaric acid;

[0026] Maleopimaric acid and polyethylene glycol are uniformly mixed, zinc oxide is added, the temperature is increased, the mixture is reacted under a nitrogen atmosphere, the temperature is decreased, the mixture is filtered, washed, and dried to obtain modified maleopimaric acid.

[0027] Furthermore, the modified maleopimaric acid is prepared by the following method:

[0028] Mix rosin and dehydrated malic anhydride evenly, heat to 160-190°C, react for 4-6 hours, cool to room temperature, wash with water for 3-5 times, and dry to obtain maleopimaric acid;

[0029] The maleopimaric acid and polyethylene glycol are uniformly mixed, zinc oxide is added, the mixture is heated to 200-220° C., reacted for 3-5 hours under a nitrogen atmosphere, cooled to room temperature, filtered, washed with water for 3-5 times, and dried to obtain modified maleopimaric acid;

[0030] The weight ratio of rosin to dehydrated malic anhydride is 1:(0.7-0.9), and the weight ratio of maleopimaric acid to zinc oxide is 1:(0.02-0.04).

[0031] Optionally, the weight ratio of maleopimaric acid to polyethylene glycol is 1:(2-4).

[0032] Optionally, the cleaning in step S1 is ultrasonic cleaning, the ultrasonic frequency is 25-45 kHz, and the cleaning time is 10-20 min.

[0033] Optionally, the pulse frequency of the electric pulse in step S2 is 1000-2000 Hz, and the current density is 20-40 A·mm -2 , with a duty cycle of 5-15%.

[0034] Optionally, in step S2, the first cooling is performed by air cooling, the second cooling is performed by salt bath, the third cooling is performed by furnace cooling, the fourth cooling is performed by air cooling, the fifth cooling is performed by oil cooling, and the sixth cooling is performed by air cooling.

[0035] Optionally, the salt bath is a sodium chloride solution with a mass fraction of 5-10%.

[0036] It can be seen from the above technical solutions that the embodiments of the present invention have the following advantages:

[0037] 1. The present application first uses modified sodium maleopimaric acid dodecylamide dicarboxylate to clean the bearing steel, remove impurities such as grease on the bearing steel, and then perform annealing. Degreasing cleaning can effectively remove grease, emulsion, iron powder and other pollutants on the surface of the bearing steel, ensure surface cleanliness, help improve the annealing effect, improve the microstructure and mechanical properties of the bearing steel, and facilitate the improvement of the quality and mechanical properties of the bearing steel after annealing. Specifically, modified sodium maleopimaric acid dodecylamide dicarboxylate is generated by addition, amidation and acid-base neutralization reaction, has stronger surface activity, can effectively reduce the surface tension of water, and can enhance the wetting and emulsification ability of water to grease; through the change of molecular structure, the adsorption and emulsification power of modified sodium maleopimaric acid dodecylamide dicarboxylate to grease are also enhanced, and the degreasing efficiency is further improved, so as to be more conducive to the cleaning of the bearing steel and facilitate the subsequent annealing operation of the bearing steel.

[0038] 2. The present application adopts polyethylene glycol to modify maleopimaric acid. Polyethylene glycol is a commonly used modifier that can increase the water solubility and stability of maleopimaric acid, thereby improving its degreasing effect. The addition of zinc oxide as a catalyst can not only promote the reaction between maleopimaric acid and polyethylene glycol and accelerate the reaction process, but zinc oxide can also enhance the degreasing effect, further improve the cleaning of bearing steel, and facilitate the subsequent annealing operation of bearing steel.

[0039] 3. The present application adopts salt bath cooling, which can effectively control the cooling process, avoid quenching stress and deformation caused by too fast cooling rate, make the bearing steel obtain uniform structure, help inhibit the formation of network carbides, improve the microstructure, and improve the hardness and wear resistance of the bearing steel; furnace cooling can control the cooling rate, ensure the uniform release of internal stress of the bearing steel, and help obtain a uniform microstructure; oil bath cooling can also control the cooling rate, avoid cracks and deformation on the surface of the bearing steel, and help improve the mechanical properties of the bearing steel, thereby improving the quality of the bearing steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0041] Figure 1It is a schematic diagram of the bearing steel spheroidizing annealing technology of the present invention. DETAILED DESCRIPTION

[0042] In order to make the technical scheme of the present invention better understood by the personnel of the technical field, the technical scheme in the embodiment of the present invention is clearly and completely described below. Obviously, the described embodiment is only a part of the embodiment of the present invention, rather than all the embodiments. Based on the embodiment in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention. Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or can be prepared by existing methods.

[0043] The relative molecular mass of polyethylene glycol is 600.

[0044] Preparation Example

[0045] Preparation Example 1

[0046] A modified maleopimaric acid is prepared by the following method:

[0047] 2 kg of rosin and 1.6 kg of dehydrated malic anhydride were mixed evenly, heated to 180°C, reacted for 5 hours, cooled to room temperature, washed with water for 5 times, and dried to obtain maleopimaric acid;

[0048] 2 kg of maleopimaric acid and 4 kg of polyethylene glycol were mixed evenly, 0.06 kg of zinc oxide was added, the mixture was heated to 210° C., reacted for 4 h under a nitrogen atmosphere, cooled to room temperature, filtered, washed with water for 5 times, and dried to obtain modified maleopimaric acid.

[0049] Preparation Example 2

[0050] A modified maleopimaric acid is different from Preparation Example 1 in that the amount of polyethylene glycol added is different. The amount of polyethylene glycol added in Preparation Example 2 is 6 kg.

[0051] Preparation Example 3

[0052] A modified maleopimaric acid is different from Preparation Example 1 in that the amount of polyethylene glycol added is different. The amount of polyethylene glycol added in Preparation Example 3 is 8 kg.

[0053] Preparation Example 4

[0054] A modified maleopimaric acid sodium dodecylamide dicarboxylate is prepared by the following method:

[0055] 1 kg of modified maleopimaric acid prepared in Preparation Example 1, 0.5 kg of dodecylamine, and 0.02 kg of ethylenediamine were placed in 7 L of 50% ethanol solution, mixed evenly, and reacted for 5 hours to obtain a mixed solution A;

[0056] 0.2 kg of sodium hydroxide was added into 5 L of 50% ethanol solution and mixed evenly to obtain a mixed solution B;

[0057] Add mixed solution A to mixed solution B, heat to 50°C, stir continuously, react for 5 hours, and after the reaction is completed, cool to room temperature, filter, collect the filtrate, and concentrate under reduced pressure to obtain modified sodium maleopimaric acid dodecanamide dicarboxylate.

[0058] Preparation Example 5

[0059] A modified sodium maleopimaric acid dodecylamide dicarboxylate, which is different from Preparation Example 4 in that the amount of dodecylamine added is different. The amount of dodecylamine added in Preparation Example 5 is 0.7 kg.

[0060] Preparation Example 6

[0061] A modified sodium maleopimaric acid dodecylamide dicarboxylate, which is different from Preparation Example 4 in that the amount of dodecylamine added is different. The amount of dodecylamine added in Preparation Example 6 is 0.9 kg.

[0062] Preparation Example 7

[0063] A modified sodium maleopimaric acid dodecanamide dicarboxylate, which is different from Preparation Example 4 in that the amount of sodium hydroxide added is different. The amount of sodium hydroxide added in Preparation Example 7 is 0.3 kg.

[0064] Preparation Example 8

[0065] A modified sodium maleopimaric acid dodecanamide dicarboxylate, which is different from Preparation Example 4 in that the amount of sodium hydroxide added is different. The amount of sodium hydroxide added in Preparation Example 8 is 0.4 kg.

[0066] Preparation Example 9

[0067] A modified maleopimaric acid sodium dodecanamide dicarboxylate, which is different from Preparation Example 7 in that the modified maleopimaric acid has a different source, and the modified maleopimaric acid in Preparation Example 9 is prepared using Preparation Example 2.

[0068] Preparation Example 10

[0069] A modified maleopimaric acid sodium dodecanamide dicarboxylate, which is different from Preparation Example 7 in that the modified maleopimaric acid has a different source, and the modified maleopimaric acid in Preparation Example 10 is prepared using Preparation Example 3.

[0070] Example

[0071] Example 1

[0072] A bearing steel spheroidizing annealing technology comprises the following steps:

[0073] S1: placing the bearing steel in a 40% mass fraction modified sodium maleopimaric acid dodecylamide dicarboxylate solution prepared in Preparation Example 4 and ultrasonically cleaning it for 15 minutes at an ultrasonic frequency of 35 kHz, taking it out, washing it with water, and drying it to obtain the cleaned bearing steel;

[0074] S2: The cleaned bearing steel is heated to 1000°C for the first time by electric pulse, kept at this temperature for 30 minutes, first cooled to 650°C by air cooling, kept at this temperature for 30 minutes, and then cooled to room temperature by salt bath using a 7% sodium chloride solution by mass, heated to 700°C for the second time, kept at this temperature for 2 hours, first cooled to 600°C by furnace cooling, and then cooled to room temperature by air cooling, heated to 850°C for the third time, kept at this temperature for 15 minutes, cooled to room temperature by oil cooling, heated to 160°C for the fourth time, kept at this temperature for 2 hours, and cooled to room temperature by air cooling, thereby obtaining the annealed bearing steel;

[0075] The pulse frequency of the electric pulse in step S2 is 1500 Hz, and the current density is 30 A·mm -2 , the duty cycle is 10%.

[0076] Embodiment 2-7

[0077] A bearing steel spheroidizing annealing technology, which differs from Example 1 in that the sources of modified maleopimaric acid sodium dodecylamide dicarboxylate are different, and the modified maleopimaric acid sodium dodecylamide dicarboxylate in Examples 2-7 are prepared using Preparation Examples 5-10, respectively.

[0078] Comparative Example

[0079] Comparative Example 1

[0080] A spheroidizing annealing technology for bearing steel, which differs from Example 1 in that an equal amount of modified maleopimaric acid in modified maleopimaric acid sodium dodecanamide dicarboxylate is replaced by unmodified maleopimaric acid.

[0081] Comparative Example 2

[0082] A spheroidizing annealing technology for bearing steel, which differs from Example 1 in that the bearing steel is not cleaned with a modified sodium maleopimaric acid dodecanamide dicarboxylate solution.

[0083] Performance testing

[0084] The bearing steels in Examples 1-7 and Comparative Examples 1-2 were subjected to the following performance tests:

[0085] Hardness: The hardness of the bearing steel was measured in accordance with GB / T230.1-2018 "Rockwell Hardness of Metallic Materials Part 1: Test Method". The test results are shown in Table 1.

[0086] Wear amount: The wear amount of bearing steel was measured according to JB / T2607-2016 “Superhard tool material performance test method”. The test results are shown in Table 1.

[0087] Impact toughness: The impact toughness of bearing steel was measured according to GB / T1817-1995 “Test method for room temperature impact toughness of cemented carbide”. The test results are shown in Table 1.

[0088] Contact fatigue strength: The contact fatigue strength of bearing steel was measured according to GB / T10622-1989 “Test method for rolling contact fatigue of metallic materials”. The test results are shown in Table 1.

[0089] Table 2 Test results

[0090]

[0091] As can be seen from Table 2, the spheroidizing annealing technology of bearing steel in the present application significantly improves the mechanical properties and wear resistance of bearing steel by first cleaning the bearing steel and then adjusting the annealing process, improves the hardness, impact toughness and contact fatigue strength of the bearing steel, and reduces the wear amount. Among them, the hardness is 62.1-63.5HRC, and the wear amount is 15.69-35.78 10 - 5 mm 3 / Nm, impact toughness is 3.7-5.2J / cm 2 , contact fatigue strength is 413-435N / m.

[0092] Combining Example 1 with Comparative Examples 1-2, it can be seen that the hardness of the bearing steel in Example 1 is 62.1HRC, and the wear loss is 35.78 10 -5 mm 3 / Nm, impact toughness is 3.7J / cm 2 The contact fatigue strength is 413N / m, which is better than that of comparative example 1-2, indicating that it is more appropriate to use modified sodium maleopimaric acid dodecylamide dicarboxylate solution to clean the bearing steel before use, which can remove grease and other dirt on the surface of the bearing steel and improve the uniformity during annealing, thereby helping to improve the mechanical properties of the bearing steel.

[0093] Combining Examples 1-3, it can be seen that the hardness of the bearing steel in Example 2 is 62.5HRC, and the wear loss is 28.4110 -5 mm 3 / Nm, impact toughness is 4.3J / cm2 , the contact fatigue strength is 421N / m, which is better than other embodiments, indicating that the addition amount of dodecylamine in Preparation Example 5 is more appropriate. If the addition amount of dodecylamine is too little, the compounding effect with modified maleopimaric acid is not good, thereby affecting the cleaning effect on the bearing steel; if the addition amount of dodecylamine is too much, it will lead to excessive dodecylamine, which is easy to form residues on the surface of the bearing steel, resulting in affecting the mechanical properties of the bearing steel; therefore, when the addition amount of dodecylamine is within a certain range, it can improve the compounding effect with modified maleopimaric acid, improve the cleaning effect on the bearing steel, and help improve the mechanical properties after annealing.

[0094] Combining Example 2 and Example 4-5, it can be seen that the hardness of the bearing steel in Example 4 is 62.9HRC, and the wear loss is 21.12 10 -5 mm 3 / Nm, impact toughness is 4.8J / cm 2 The contact fatigue strength is 426 N / m, which is better than other embodiments, indicating that the amount of sodium hydroxide added in Preparation Example 7 is more appropriate. If the amount of sodium hydroxide added is too little, the compounding effect with modified maleopimaric acid is not good, which will affect the cleaning effect of bearing steel; if the amount of sodium hydroxide added is too much, the solution will be alkaline, which will also affect the cleaning effect; therefore, when the amount of sodium hydroxide added is within a certain range, it can improve the compounding effect with maleopimaric acid and the cleaning effect, thereby helping to improve the uniformity during annealing and improve the quality of bearing steel.

[0095] Combining Example 4 and Example 6-7, it can be seen that the hardness of the bearing steel in Example 6 is 63.5HRC, and the wear loss is 15.69 10 -5 mm 3 / Nm, impact toughness is 5.2J / cm 2 , the contact fatigue strength is 435N / m, which is better than other embodiments, indicating that the modified maleopimaric acid is more suitable for preparation using Preparation Example 2, and the amount of polyethylene glycol added in Preparation Example 2 is more suitable. If the amount of polyethylene glycol added is too little, the maleopimaric acid cannot be modified better, resulting in a poor cleaning effect of the modified maleopimaric acid; if the amount of polyethylene glycol added is too much, it may occupy the reaction sites and hinder the effective contact between maleopimaric acid and polyethylene glycol, thereby reducing the reaction efficiency and affecting the yield of the modified maleopimaric acid; therefore, when the amount of polyethylene glycol added is within a certain range, the maleopimaric acid can be better modified, which is more helpful to improve the cleaning effect on the bearing steel and facilitate the improvement of the quality of the bearing steel.

[0096] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A bearing steel spheroidizing annealing technology, characterized in that: The steps include: S1: washing the bearing steel in a modified sodium maleopimaric acid dodecylamide dicarboxylate solution, taking out, washing with water, and drying to obtain the washed bearing steel; S2: The cleaned bearing steel is heated to 900-1100°C for the first time by electric pulse, kept warm, first cooled to 600-700°C, kept warm, and then cooled to room temperature, heated to 650-750°C for the second time, kept warm, first cooled to 500-700°C, and then cooled to room temperature, heated to 800-900°C for the third time, kept warm, and cooled to room temperature, heated to 120-200°C for the fourth time, kept warm, and cooled to room temperature to obtain annealed bearing steel.

2. The bearing steel spheroidizing annealing technology according to claim 1, characterized in that: The modified maleopimaric acid sodium dodecanamide dicarboxylate is prepared by the following method: Put modified maleopimaric acid, dodecylamine and ethylenediamine into an ethanol solution, mix well, and react to obtain a mixed solution A; Put sodium hydroxide into the ethanol solution and mix well to obtain a mixed solution B; The mixed solution A is added to the mixed solution B, and the mixture is heated and stirred continuously to react. After the reaction is completed, the mixture is cooled and filtered, and the filtrate is collected and concentrated under reduced pressure to obtain modified sodium maleopimaric acid dodecanamide dicarboxylate.

3. The bearing steel spheroidizing annealing technology according to claim 2 is characterized in that: The weight ratio of the modified maleopimaric acid, dodecylamine and sodium hydroxide is 1:(0.5-0.9):(0.2-0.4).

4. The bearing steel spheroidizing annealing technology according to claim 1, characterized in that: The modified maleopimaric acid is prepared by the following method: The rosin and dehydrated malic anhydride are uniformly mixed, heated, reacted, cooled, washed, and dried to obtain maleopimaric acid; Maleopimaric acid and polyethylene glycol are uniformly mixed, zinc oxide is added, the temperature is increased, the mixture is reacted under a nitrogen atmosphere, the temperature is decreased, the mixture is filtered, washed, and dried to obtain modified maleopimaric acid.

5. The bearing steel spheroidizing annealing technology according to claim 4 is characterized in that: The weight ratio of maleopimaric acid to polyethylene glycol is 1:(2-4).

6. The bearing steel spheroidizing annealing technology according to claim 1, characterized in that: The cleaning in step S1 is ultrasonic cleaning, the ultrasonic frequency is 25-45kHz, and the cleaning time is 10-20min.

7. The bearing steel spheroidizing annealing technology according to claim 1, characterized in that: The pulse frequency of the electric pulse in step S2 is 1000-2000 Hz, and the current density is 20-40 A·mm -2 , with a duty cycle of 5-15%.

8. The bearing steel spheroidizing annealing technology according to claim 1, characterized in that: In step S2, the first cooling is performed by air cooling, the second cooling is performed by salt bath, the third cooling is performed by furnace cooling, the fourth cooling is performed by air cooling, the fifth cooling is performed by oil cooling, and the sixth cooling is performed by air cooling.

9. The bearing steel spheroidizing annealing technology according to claim 8, characterized in that: The salt bath is a sodium chloride solution with a mass fraction of 5-10%.

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