Heat treatment process of high-temperature bearing steel

Abstract

The invention discloses a heat treatment process of high-temperature bearing steel, a used heat treatment sample is GCr4Mo4V high-temperature bearing steel, and heat treatment is performed according to the following steps: (1) quenching: putting a high-temperature bearing steel blank sample subjected to rough machining into a heating furnace, heating to 1080-1100 DEG C, preserving heat for 50-70 minutes, then quenching, and cooling in oil; and (2) tempering: putting the quenched sample into a heating furnace, heating to 530-550 DEG C, preserving heat for 120-150 minutes, then taking out the sample, cooling in air, and tempering for three times. A sample subjected to heat treatment is subjected to mechanical property inspection, the tensile strength at the normal temperature is 650-850 MPa, and the Brinell hardness HBW is 197-241; the austenite grain size of the steel is larger than or equal to grade 6, and the surface of the steel is free of cracks, scabs, folds or inclusions.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-temperature bearing steel manufacturing, and particularly relates to a heat treatment process for high-temperature bearing steel. Background Art

[0002] Heat treatment can change the crystal structure and tissue state of steel, thereby adjusting its mechanical properties, such as hardness, strength, toughness, etc. A reasonable heat treatment system can enable spring steel to reach the required mechanical property indexes. High-temperature bearing steel needs to maintain excellent properties under extreme conditions, such as high strength, hardness, wear resistance, and oxidation resistance. The heat treatment process can significantly improve the microstructure of materials by controlling parameters such as temperature, time, and cooling rate, forming the required martensite, carbide and other structures, thereby optimizing these key properties. Therefore, it is particularly important to formulate a suitable heat treatment process to ensure that high-temperature bearing steel has good properties. Through the study of the phase transformation points of GCr4Mo4V high-temperature bearing steel, it is found that the quenching heat treatment temperature of high-temperature bearing steel should be controlled at 1080°C - 1100°C preferably, and the quenching heating and holding time should be 50 - 70 minutes preferably; choosing oil with a lower cooling rate as the quenching medium can obtain appropriate strength. The tempering temperature should be controlled at 530 - 550°C preferably, the tempering holding time should be 120 - 150 minutes preferably, and the number of tempering times should be 3 times preferably.

[0003] Publication No. CN 118531189 A introduces a heat treatment process for grain refinement of high-temperature bearing steel Cr4Mo4V, including steps such as multiple high-temperature homogenization, furnace cooling, austenitization, quenching, activation, cryogenic treatment, and carbide removal, to improve the grain size to meet the preparation requirements of high-service-life bearings. This patent introduces a heat treatment process for GCr4Mo4V high-temperature bearing steel, including quenching and tempering steps, and improves the comprehensive mechanical properties of bearing steel by controlling temperature and holding time. This patent focuses on the optimization of the conventional heat treatment process of GCr4Mo4V high-temperature bearing steel, improves the performance by precisely controlling the quenching and tempering parameters (temperature, time), and has a more in-depth and targeted research on the heat treatment process, which can better ensure the performance of steel.

[0004] Publication number CN 114457212 A introduces a carbide fine and dispersed treatment process for high-temperature bearing steel, including two-stage pretreatment of ingots, upsetting and drawing, primary heat treatment, drawing, secondary heat treatment and other processes, making the carbides fine, dispersed and evenly distributed, and improving the mechanical properties. This patent introduces a heat treatment process for GCr4Mo4V high-temperature bearing steel, including quenching and tempering steps. By controlling the temperature and holding time, the comprehensive mechanical properties of the bearing steel are improved. This patent focuses on the optimization of the conventional heat treatment process of GCr4Mo4V high-temperature bearing steel. By precisely controlling the quenching and tempering parameters (temperature, time), the performance is improved. The research on the heat treatment process is more in-depth and targeted, and can better ensure the performance of the steel.

[0005] Publication number CN 113564317 A introduces a heat treatment method for controlling the microstructure and properties of high-temperature bearing steel (8Cr4Mo4V), including spheroidizing annealing, vacuum isothermal quenching and three-stage tempering treatment, which can improve the strength and impact toughness of the steel. This patent introduces a heat treatment process for GCr4Mo4V high-temperature bearing steel, including quenching and tempering steps. By controlling the temperature and holding time, the comprehensive mechanical properties of the bearing steel are improved. This patent focuses on the optimization of the conventional heat treatment process of GCr4Mo4V high-temperature bearing steel. By precisely controlling the quenching and tempering parameters (temperature, time), the performance is improved. The research on the heat treatment process is more in-depth and targeted, and can better ensure the performance of the steel. Summary of the Invention

[0006] The purpose of the present invention is to provide a heat treatment process for high-temperature bearing steel, so that it has good comprehensive mechanical properties, and thus significantly improve the overall life and safety of high-temperature bearing steel.

[0007] To solve the above technical problems, the present invention adopts the following technical solutions:

[0008] For the heat treatment process of a high-temperature bearing steel of the present invention, the rough-machined high-temperature bearing steel blank sample is placed in a heating furnace, heated to 1080°C - 1100°C, held for 50 - 70 min, and then quenched and cooled in oil; the quenched sample is placed in a heating furnace, heated to 530 - 550°C, held for 120 - 150 min, and then the sample is taken out and cooled in air, and tempered 3 times.

[0009] Furthermore, the chemical composition of the high-temperature bearing steel by mass percentage is: C 0.75 - 0.85%, Si 0.18 - 0.25%, Mn 0.20 - 0.30%, P ≤ 0.02%, S ≤ 0.01%, Cr 4.0 - 4.1%, Mo 4.2 - 4.3%, V 1.0 - 1.1%, and the rest is Fe and inevitable impurities.

[0010] Further, put the rough-machined high-temperature bearing steel blank sample into a heating furnace, raise the temperature to 1080 °C, hold for 50 min, then perform quenching and cool in oil; put the quenched sample into the heating furnace, heat to 530 °C, hold for 120 min, then take out the sample and cool in air, and temper 3 times.

[0011] Further, put the rough-machined high-temperature bearing steel blank sample into a heating furnace, raise the temperature to 1090 °C, hold for 50 min, then perform quenching and cool in oil; put the quenched sample into the heating furnace, heat to 540 °C, hold for 120 min, then take out the sample and cool in air, and temper 3 times.

[0012] Further, put the rough-machined high-temperature bearing steel blank sample into a heating furnace, raise the temperature to 1100 °C, hold for 50 min, then perform quenching and cool in oil; put the quenched sample into the heating furnace, heat to 550 °C, hold for 120 min, then take out the sample and cool in air, and temper 3 times.

[0013] Further, the chemical composition of the high-temperature bearing steel by mass percentage is: C 0.80%, Si 0.21%, Mn 0.27%, P 0.014%, S 0.006%, Cr 4.09%, Mo 4.25%, V 1.08%, and the rest is Fe and unavoidable impurities.

[0014] Further, the chemical composition of the high-temperature bearing steel by mass percentage is: C 0.81%, Si 0.22%, Mn 0.28%, P 0.016%, S 0.004%, Cr 4.08%, Mo 4.27%, V 1.07%, and the rest is Fe and unavoidable impurities.

[0015] Further, the chemical composition of the high-temperature bearing steel by mass percentage is: C 0.79%, Si 0.21%, Mn 0.27%, P 0.018%, S 0.005%, Cr 4.11%, Mo 4.26%, V 1.08%, and the rest is Fe and unavoidable impurities.

[0016] Further, the heat-treated sample used is GCr4Mo4V high-temperature bearing steel.

[0017] Compared with the prior art, the beneficial technical effects of the present invention:

[0018] (1) Through an optimized heat treatment process (rationally controlling the quenching temperature, tempering temperature, and multiple tempering processes), the present invention significantly improves the tensile strength, hardness, and toughness of high-temperature bearing steel, ensuring that it can still maintain excellent comprehensive mechanical properties in high-temperature environments and extending the service life of the material; (2) By adopting oil quenching and three-time tempering processes, the residual stress generated during the heat treatment process is effectively reduced, and the risk of material deformation and cracking is reduced, thereby improving the dimensional stability and durability of the product, especially having higher reliability under long-term high-temperature use conditions; (3) By reasonably shortening the holding time, optimizing the quenching and tempering temperature ranges, the present invention reduces the energy waste during the heat treatment process, lowers the overall energy consumption, and improves the production efficiency at the same time, making it suitable for large-scale industrial production.

[0019] For the heat treatment process of the high-temperature bearing steel of the present invention, by studying the heat treatment heating system, including the effects of quenching temperature, tempering temperature, holding time, etc. on the performance, a heat treatment system that can ensure the stable performance of the steel is determined. Specific embodiments

[0020] Example 1:

[0021] The steel part in the heat treatment process of the present invention is GCr4Mo4V high-temperature bearing steel, and the steps are as follows:

[0022] (1) Quenching: Put the rough-machined blank sample of high-temperature bearing steel into a heating furnace, heat it up to 1080 °C, hold for 50 min, and then perform quenching and cool in oil;

[0023] (2) Tempering: Put the quenched sample into a heating furnace, heat it to 530 °C, hold for 120 min, then take out the sample and cool it in the air, and temper 3 times.

[0024] Example 2:

[0025] The steel part in the heat treatment process of the present invention is GCr4Mo4V high-temperature bearing steel, and the steps are as follows:

[0026] (1) Quenching: Put the rough-machined blank sample of high-temperature bearing steel into a heating furnace, heat it up to 1090 °C, hold for 70 min, and then perform quenching and cool in oil;

[0027] (2) Tempering: Put the quenched sample into a heating furnace, heat it to 540 °C, hold for 150 min, then take out the sample and cool it in the air, and temper 3 times.

[0028] Example 3:

[0029] The steel part in the heat treatment process of the present invention is GCr4Mo4V high-temperature bearing steel, and the steps are as follows:

[0030] (1) Quenching: Put the rough - machined high - temperature bearing steel blank into a heating furnace, raise the temperature to 1100 °C, hold for 60 min, then perform quenching and cool in oil;

[0031] (2) Tempering: Put the quenched sample into a heating furnace, heat to 550 °C, hold for 140 min, then take out the sample and cool in air, temper 3 times.

[0032] Comparative Example 1:

[0033] The steel part in the heat treatment process of the present invention is GCr4Mo4V high - temperature bearing steel, and the steps are as follows:

[0034] (1) Quenching: Put the rough - machined high - temperature bearing steel blank into a heating furnace, raise the temperature to 1030 °C, hold for 30 min, then perform quenching and cool in water;

[0035] (2) Tempering: Put the quenched sample into a heating furnace, heat to 500 °C, hold for 100 min, then take out the sample and cool in air, temper 3 times.

[0036] Comparative Example 2:

[0037] The steel part in the heat treatment process of the present invention is GCr4Mo4V high - temperature bearing steel, and the steps are as follows:

[0038] (1) Quenching: Put the rough - machined high - temperature bearing steel blank into a heating furnace, raise the temperature to 1150 °C, hold for 60 min, then perform quenching and cool in oil;

[0039] (2) Tempering: Put the quenched sample into a heating furnace, heat to 600 °C, hold for 150 min, then take out the sample and cool in air, temper 3 times.

[0040] Comparative Example 3:

[0041] The steel part in the heat treatment process of the present invention is GCr4Mo4V high - temperature bearing steel, and the steps are as follows:

[0042] (1) Quenching: Put the rough - machined high - temperature bearing steel blank into a heating furnace, raise the temperature to 1070 °C, hold for 40 min, then perform quenching and cool in oil;

[0043] (2) Tempering: Put the quenched sample into a heating furnace, heat to 500 °C, hold for 90 min, then take out the sample and cool in air, temper 3 times.

[0044] Comparative Example 4:

[0045] The steel part in the heat treatment process of the present invention is GCr4Mo4V high-temperature bearing steel, and the process is carried out according to the following steps:

[0046] (1) Quenching: Put the rough-machined high-temperature bearing steel blank into a heating furnace, heat it up to 1080 °C, hold for 50 min, and then quench it, cooling in oil;

[0047] (2) Tempering: Put the quenched sample into a heating furnace, heat it to 530 °C, hold for 120 min, then take out the sample and cool it in air, tempering only once.

[0048] After the heat treatment is completed, finish-machine the rough-machined blank, conduct various performance tests. The chemical compositions of each example and comparative example are shown in Table 1, the specific process parameters of each example and comparative example are shown in Table 2, and the test results are shown in Tables 3 and 4. It can be seen from Tables 3 and 4 that all performance indicators are higher than the required indicators, and the performance of the specimens after heat treatment is qualified.

[0049] Table 1 Chemical Compositions of Each Example and Comparative Example

[0050]

[0051]

[0052] Table 2 Specific Process Parameters of Each Example and Comparative Example

[0053]

[0054] Table 3 Mechanical Properties after Heat Treatment

[0055]

[0056]

[0057] Table 4 Non-Metallic Inclusions and Austenite Grain Size of GCr4Mo4V Steel for High-Temperature Bearings in Each Example

[0058]

[0059] As can be seen from the above examples and comparative examples: (1) Compared with the examples, in Comparative Example 1, too low quenching temperature and tempering temperature will lead to insufficient elimination of martensite structure inside the material, thereby reducing strength and hardness, and it is not suitable for high-temperature and long-time use scenarios. Although water cooling can rapidly cool, it is prone to causing cracks and increasing internal stress, affecting the toughness and service life of the material. (2) Compared with the examples, in Comparative Example 2, too high quenching temperature will lead to coarse grains. Although the hardness can be increased in a short time, the material will become brittle during long-term use. The overall comprehensive performance is poor and cannot reach the ideal tensile strength and hardness. (3) Compared with the examples, in Comparative Example 3, too low tempering temperature and short-time heat preservation result in insufficient strength and hardness of the material, which will lead to a reduction in the service life of the material in actual applications. (4) Compared with the examples, in Comparative Example 4, only one tempering will result in incomplete elimination of residual stress in the material, affecting the service life. Multiple temperings can effectively remove the residual stress in the material and improve the overall performance and stability.

[0060] The heat treatment process of the high-temperature bearing steel of the present invention has the following advantages: (1) By precisely controlling the quenching temperature (1080°C - 1100°C) and tempering temperature (530°C - 550°C) in the examples and adopting a multiple tempering process, the tensile strength and hardness of the material are significantly higher than those of the comparative examples. For example, the tensile strength of Comparative Example 1 is 670 MPa and the Brinell hardness is 190, while the tensile strength of the example reaches 777 MPa and the Brinell hardness is 225. This performance advantage makes the example more suitable for long-term use under high load and high-temperature environments; (2) By optimizing the heat treatment process in the examples, the austenite grain size of the material is effectively controlled, and the grain size reaches the level of 6.5 - 7.0, while the grain size of the comparative examples is generally lower, at 5.0 - 6.0, and the grains are relatively coarse. Grain refinement helps to improve the strength of the material, especially showing higher stability in high-temperature applications. (3) The examples show better purity in the control of non-metallic inclusions. For example, the inclusions in the examples are all lower than those of the comparative examples (such as inclusions such as A fine, B fine, and C fine are basically 0), while the non-metallic inclusions in the comparative examples are relatively high. This means that the materials in the examples have better machining performance and anti-fatigue performance, reducing the tendency of cracks and defects in the actual application of the materials and improving the service life of the products.

[0061] The above-described examples are only descriptions of the preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A heat treatment process for high-temperature bearing steel, characterized in that, Put the rough-machined high-temperature bearing steel blank sample into a heating furnace, heat it up to 1080°C - 1100°C, hold for 50 - 70 min, then quench it and cool in oil; put the quenched sample into the heating furnace, heat it to 530 - 550°C, hold for 120 - 150 min, then take out the sample and cool it in air, and temper it 3 times.

2. The heat treatment process of the high-temperature bearing steel according to claim 1, wherein, The chemical composition of the high-temperature bearing steel by mass percentage is: C 0.75 - 0.85%, Si 0.18 - 0.25%, Mn 0.20 - 0.30%, P ≤ 0.02%, S ≤ 0.01%, Cr 4.0 - 4.1%, Mo 4.2 - 4.3%, V 1.0 - 1.1%, and the rest is Fe and inevitable impurities.

3. The heat treatment process of the high-temperature bearing steel according to claim 1, characterized in that, Put the rough-machined high-temperature bearing steel blank sample into a heating furnace, heat it up to 1080°C, hold for 50 min, then quench it and cool in oil; put the quenched sample into the heating furnace, heat it to 530°C, hold for 120 min, then take out the sample and cool it in air, and temper it 3 times.

4. The heat treatment process of the high-temperature bearing steel according to claim 1, characterized in that, Put the rough-machined high-temperature bearing steel blank sample into a heating furnace, heat it up to 1090°C, hold for 50 min, then quench it and cool in oil; put the quenched sample into the heating furnace, heat it to 540°C, hold for 120 min, then take out the sample and cool it in air, and temper it 3 times.

5. The heat treatment process of the high-temperature bearing steel according to claim 1, characterized in that, Put the rough-machined high-temperature bearing steel blank sample into a heating furnace, heat it up to 1100°C, hold for 50 min, then quench it and cool in oil; put the quenched sample into the heating furnace, heat it to 550°C, hold for 120 min, then take out the sample and cool it in air, and temper it 3 times.

6. The heat treatment process of the high-temperature bearing steel according to claim 3, characterized in that, The chemical composition of the high-temperature bearing steel by mass percentage is: C 0.80%, Si 0.21%, Mn 0.27%, P 0.014%, S 0.006%, Cr 4.09%, Mo 4.25%, V 1.08%, and the rest is Fe and inevitable impurities.

7. The heat treatment process of the high-temperature bearing steel according to claim 4, characterized in that, The chemical composition of the high-temperature bearing steel by mass percentage is: C 0.81%, Si 0.22%, Mn 0.28%, P 0.016%, S 0.004%, Cr 4.08%, Mo 4.27%, V 1.07%, and the rest is Fe and inevitable impurities.

8. The heat treatment process of the high-temperature bearing steel according to claim 5, characterized in that, The chemical composition of the high-temperature bearing steel by mass percentage is: C 0.79%, Si 0.21%, Mn 0.27%, P 0.018%, S 0.005%, Cr 4.11%, Mo 4.26%, V 1.08%, and the rest is Fe and inevitable impurities.

9. The heat treatment process of the high-temperature bearing steel according to claim 1, characterized in that, The heat-treated sample used is GCr4Mo4V high-temperature bearing steel.

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