High-toughness and high-wear-resistance bearing steel, and preparation method and application thereof

Abstract

The application provides a high-toughness and high-wear-resistance bearing steel as well as a preparation method and application thereof, and belongs to the technical field of high-wear-resistance bearing steel metallurgy.The application realizes the homogenization of the composition in the bearing steel, the small matrix structure and carbide by accurately limiting the chemical composition ratio, adopting a composite shear flow casting technology and a specific heat treatment process, and improves the wear resistance of the bearing steel.The preparation method has strong operability, and the composition is controllable.Compared with a traditional gravity casting process, the composite shear flow casting technology adopted by the application can avoid the composition and matrix structure inhomogeneity caused by the traditional gravity casting, and the heat treatment process can make the matrix structure and carbide small, which is beneficial to simultaneously improving the toughness, hardness and wear resistance, and can be popularized and applied in industry.

Description

Technical Field

[0001] This invention relates to the field of metallurgical technology for high wear-resistant bearing steel, and particularly to a high-toughness, high-wear-resistant bearing steel, its preparation method, and its applications. Background Technology

[0002] With the rapid development of aerospace technology, bearing steel faces increasingly harsh operating conditions during service, including high loads, high friction, severe stress concentration, and ultra-high operating temperatures. Insufficient lubrication, frequent start-stop cycles, and sudden speed changes often lead to slippage and dry friction at the bearing contact interface, resulting in uncontrolled temperature rise and inducing adhesive wear. These processes are usually accompanied by subsurface microstructure evolution and surface degradation, significantly weakening bearing performance and drastically shortening its service life. In actual bearing operation, friction-induced adhesive wear and thermal damage are among the main failure modes affecting the reliability of critical aerospace components. The wear resistance of bearing steel largely depends on its intrinsic factors, such as chemical composition, microstructure morphology, and mechanical properties. According to reports, approximately 75% of bearing failures are related to wear, which can even lead to catastrophic system failures in severe cases. Therefore, in aerospace applications, achieving high hardness and excellent wear resistance is crucial for the long-term service performance and reliability of bearing steel.

[0003] Currently, the widely used high-carbon chromium bearing GCr15, due to its limited temperature resistance, can no longer meet the wear resistance requirements of this new and complex working condition. In view of this, researchers, drawing on relevant high-speed tool steels, have developed a high-temperature bearing steel, 8Cr4Mo4V (known internationally as M50 steel), through careful design and imitation. 8Cr4Mo4V is a molybdenum-containing semi-high-speed steel with many significant advantages. It boasts a high fatigue life, maintaining good working condition under long-term repeated stress; its high-temperature hardness is excellent, maintaining 58 HRC at 400℃; and it also possesses high strength and high toughness, exhibiting outstanding overall performance.

[0004] However, during the casting process, as the ingot enters the final solidification stage, the feeding channels in the central region gradually narrow. Simultaneously, the melt temperature decreases and the viscosity increases significantly, making it even more difficult for the central region of the ingot to receive molten material for feeding. Taking traditional gravity casting as an example, gravity alone is usually insufficient to fully meet the feeding requirements. As a result, the molten material feeding channels are easily blocked. Furthermore, a significant temperature gradient exists from the edge to the center of the ingot. The combined effect of these factors makes the central region of the ingot highly susceptible to defects such as shrinkage cavities, porosity, segregation, and cracks, severely damaging the macroscopic quality of the ingot. It is worth noting that M50 bearing steel, due to its high carbon and alloy element content, exhibits a large temperature variation range and a wide solidification pasty zone during solidification. These characteristics make it particularly prone to severe central shrinkage cavities, porosity, segregation, and cracks. Even more challenging is that these defects are extremely difficult to completely eliminate in subsequent heating and forging processes, negatively impacting the mechanical properties and service life of the product. Therefore, there is an urgent need to provide new high-toughness and high-wear-resistant bearing steels to solve the problem that the ingot structure of M50 bearing steel in the existing technology is prone to defects and segregation, resulting in low toughness and poor wear resistance. Summary of the Invention

[0005] The purpose of this invention is to provide a high-toughness and high-wear-resistant bearing steel, its preparation method and application, which can solve the problem that defects and segregation are easily formed in the ingot structure of M50 bearing steel in the prior art, resulting in low toughness and poor wear resistance.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a high-toughness and high-wear-resistant bearing steel, the chemical composition of which, by mass percentage, includes: C 0.78~0.88%, Si 0.30~0.35%, Mn 0.30~0.35%, Cr 3.75~4.50%, Ni 0.03~0.045%, Mo 4.30~4.70%, Al 0.040~0.070%, Nb 0.14~0.16%, V 0.90~1.25%, with the balance being Fe; The preparation method of the high-toughness and high-wear-resistant bearing steel includes the following steps: The raw materials corresponding to the chemical composition of the high wear-resistant bearing steel are mixed and vacuum melted to obtain molten steel. The molten steel is poured into a multi-mode electromagnetic stirring device and subjected to composite shear flow casting to obtain steel ingots; The steel ingot is preheated, quenched, and tempered three times in sequence to obtain high-toughness and high-wear-resistant bearing steel.

[0007] Preferably, the chemical composition of the high-toughness and high-wear-resistant bearing steel, by mass percentage, includes: C 0.81~0.85%, Si 0.32~0.33%, Mn 0.31~0.33%, Cr 3.85~4.21%, Ni 0.038~0.04%, Mo 4.40~4.38%, Al 0.05~0.061%, Nb 0.15~0.16%, V 0.95~1.15%, with the balance being Fe.

[0008] This invention provides a method for preparing the high-toughness and high-wear-resistant bearing steel described in the above technical solution, comprising the following steps: The raw materials corresponding to the chemical composition of the high wear-resistant bearing steel are mixed and vacuum melted to obtain molten steel. The molten steel is poured into a multi-mode electromagnetic stirring device and subjected to composite shear flow casting to obtain steel ingots; The steel ingot is preheated, quenched, and tempered three times in sequence to obtain high-toughness and high-wear-resistant bearing steel.

[0009] Preferably, the vacuum degree of the vacuum melting is 5~10Pa, and the power of the vacuum melting is 50~180kW.

[0010] Preferably, the vacuum degree of the casting is 1~5Pa, and the casting power is 60~100kW.

[0011] Preferably, in the composite shear flow casting step, the equipment rotation speed is 15~25 r / min, the rotation speed ratio of the revolution position to the rotation position is 1:0.65~0.85, and the composite shear flow casting time is 15~25 min.

[0012] Preferably, the preheating temperature is 630℃~680℃; the preheating time is 20~40 min.

[0013] Preferably, the quenching temperature is 1020~1080℃; the quenching time is 8~16 min.

[0014] Preferably, in the three tempering steps, the temperature of each tempering is independently 480~540℃, and the time of each tempering is independently 100~140 min.

[0015] This invention provides the application of the high-toughness and high-wear-resistant bearing steel described in the above technical solution or the high-toughness and high-wear-resistant bearing steel prepared by the preparation method described in the above technical solution in the aerospace field.

[0016] This invention provides a high-toughness, high-wear-resistant bearing steel. By precisely defining the chemical composition ratio, employing composite shear flow casting technology and a specific heat treatment process, the composition of the bearing steel is homogenized, and the matrix structure and carbides are fine, thereby improving the toughness, hardness, and wear resistance of the bearing steel. The main role of the specific alloying elements is to participate in the formation of various fine carbides. Furthermore, Cr can promote oxidative wear during friction and wear, leading to the formation of a dense oxide film and improving wear resistance. The preparation method of this invention is highly operable and the composition is controllable. Compared with traditional gravity casting, the composite shear flow casting technology used in this invention avoids the inhomogeneity of composition and matrix structure caused by traditional gravity casting. Combined with the heat treatment process, it results in a fine matrix structure and carbides, which is beneficial for simultaneously improving its toughness, hardness, and wear resistance, and can be industrially promoted and applied.

[0017] During casting, this invention effectively controls defects such as shrinkage cavities, porosity, and cracks by applying a composite shear flow, significantly improving the macroscopic low-magnification quality of the ingot, inhibiting the growth of columnar crystal regions, providing excellent ingots for subsequent processes, and, combined with heat treatment, making its matrix structure and carbides fine, which is beneficial to simultaneously improving its toughness, hardness, and wear resistance, and can be industrially promoted and applied.

[0018] This invention employs a preheating, quenching, and three-stage tempering process to control various microstructures and carbides in bearing steel. The resulting high-toughness, high-wear-resistant bearing steel primarily exhibits a martensitic tempered matrix. The high-toughness, high-wear-resistant bearing steel of this invention has a hardness ≥62 HRC, impact energy ≥15.08 J, and wear volume ≤3.17 × 10⁻⁶. 7 μm 3 The average coefficient of friction is ≤0.555. Attached Figure Description

[0019] Figure 1 The image shows the microstructure of the high-toughness and high-wear-resistant bearing steel prepared in Example 1. Detailed Implementation

[0020] In this invention, unless otherwise specified, the raw materials or reagents required for preparation are all commercially available products well known to those skilled in the art.

[0021] This invention provides a high-toughness and high-wear-resistant bearing steel, the chemical composition of which, by mass percentage, includes: C 0.78~0.88%, Si 0.30~0.35%, Mn 0.30~0.35%, Cr 3.75~4.50%, Ni 0.03~0.045%, Mo 4.30~4.70%, Al 0.040~0.070%, Nb 0.14~0.16%, V 0.90~1.25%, with the balance being Fe; The preparation method of the high-toughness and high-wear-resistant bearing steel includes the following steps: The raw materials corresponding to the chemical composition of the high wear-resistant bearing steel are mixed and vacuum melted to obtain molten steel. The molten steel is poured into a multi-mode electromagnetic stirring device and subjected to composite shear flow casting to obtain steel ingots; The steel ingot is preheated, quenched, and tempered three times in sequence to obtain high-toughness and high-wear-resistant bearing steel.

[0022] As a preferred embodiment of the present invention, the chemical composition of the high-toughness and high-wear-resistant bearing steel, by mass percentage, includes: C 0.81~0.85%, Si 0.32~0.33%, Mn 0.31~0.33% (more preferably 0.32%), Cr 3.85~4.21%, Ni 0.038~0.04%, Mo 4.40~4.38%, Al 0.05~0.061%, Nb 0.15~0.16%, V 0.95~1.15%, with the balance being Fe.

[0023] This invention provides a method for preparing the high-toughness and high-wear-resistant bearing steel described in the above technical solution, comprising the following steps: The raw materials corresponding to the chemical composition of the high wear-resistant bearing steel are mixed and vacuum melted to obtain molten steel. The molten steel is poured into a multi-mode electromagnetic stirring device and subjected to composite shear flow casting to obtain steel ingots; The steel ingot is preheated, quenched, and tempered three times in sequence to obtain high-toughness and high-wear-resistant bearing steel.

[0024] The present invention does not impose any special limitations on the specific specifications and sources of the raw materials corresponding to the chemical composition of the high wear-resistant bearing steel; any corresponding raw materials well known in the art are acceptable.

[0025] In this invention, the vacuum degree of the vacuum melting is preferably 5-10 Pa, more preferably 6-9 Pa, and even more preferably 7-8 Pa; the power of the vacuum melting is preferably 50-180 kW, more preferably 60-170 kW, and even more preferably 90-150 kW; the temperature of the vacuum melting is preferably 1600-1620℃. This invention preferably uses a medium-frequency power supply, increases the melting power according to the furnace conditions in a manner well-known in the art, performs vacuum melting, and after melting is completed, shuts off the vacuum pump while simultaneously introducing argon gas into the furnace to increase the furnace vacuum pressure to 200-250 Pa, thereby obtaining molten steel.

[0026] After completing the vacuum melting, the present invention preferably adjusts the temperature of the molten steel to meet the tapping requirements (i.e., tapping temperature of 1500~1530℃, more preferably 1510~1511℃), then pours all the molten steel into the ingot mold, turns on the multi-modal electromagnetic stirring device, performs composite shear flow casting, and stops the machine to remove the steel ingot after cooling. The multi-modal electromagnetic stirring device mentioned in the present invention is "A Mechanical and Electromagnetic Stirring Device for Alloy Solution" disclosed in Chinese Patent CN 115647304 A.

[0027] In this invention, the vacuum degree of the casting is preferably 1~5Pa, preferably 2~4Pa, and more preferably 3Pa; the casting power is preferably 60~100kW, preferably 65~95kW, and more preferably 70~80kW.

[0028] In this invention, in the composite shear flow casting step, the equipment rotation speed is preferably 15~25 r / min, more preferably 20~22 r / min, and the rotation speed ratio of the revolution position to the rotation position is preferably 1:0.65~0.85, more preferably 1:0.7~0.75; the composite shear flow casting time is preferably 15~25 min, more preferably 20~22 min.

[0029] In this invention, the preheating temperature is preferably 630℃~680℃, more preferably 640℃~670℃, and even more preferably 652℃~654℃; the preheating time is preferably 20~40 min, more preferably 25~35 min, and even more preferably 26~28 min.

[0030] In this invention, the quenching temperature is preferably 1020~1080℃, preferably 1030~1070℃, and more preferably 1050~1055℃; the quenching time is preferably 8~16 min, preferably 9~15 min, and more preferably 10~14 min.

[0031] In this invention, during the three tempering steps, the temperature of each tempering is preferably 480~540℃, more preferably 510~530℃, and even more preferably 512~515℃; the duration of each tempering is preferably 100~140 min, more preferably 110~130 min, and even more preferably 115~120 min. The cooling method after each tempering holding is air cooling.

[0032] This invention provides the application of the high-toughness and high-wear-resistant bearing steel described in the above technical solution or the high-toughness and high-wear-resistant bearing steel prepared by the preparation method described in the above technical solution in the aerospace field.

[0033] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0034] Unless otherwise specified, the experimental methods described in the various embodiments of this invention are conventional methods; unless otherwise specified, the raw materials used are all commercially available products, and the proportions are all by mass percentage.

[0035] Example 1

[0036] The chemical composition of the high-toughness and high-wear-resistant bearing steel provided in this embodiment is: C 0.81%, Si 0.32%, Mn 0.31%, Cr 3.85%, Ni 0.04%, Mo 4.40%, Al 0.050%, Nb 0.15%, V 0.95%, balance Fe; Accurately weigh 200 kg per furnace. Add the raw materials corresponding to the chemical composition of the high-toughness and high-wear-resistant bearing steel in the manner of placing large pieces near the inner wall of the crucible and small pieces near the center of the crucible. Close the furnace lid, turn on the vacuum pump, and evacuate the furnace to a vacuum level of 8.0 Pa for vacuum melting. The vacuum melting temperature is 1600℃. The vacuum melting process is as follows: set the furnace power to 90kW and heat it up. When the metal in the crucible begins to melt, increase the power to 160kW for melting. When splashing occurs, reduce the power to 70kW, turn off the vacuum pump, and simultaneously introduce argon gas into the furnace to increase the vacuum pressure to 200 Pa. After completion, molten steel is obtained. After adjusting the molten steel temperature to reach the tapping temperature of 1510℃, all the molten steel is poured into the ingot mold. The vacuum degree of pouring is 3Pa, and the pouring power is 80kW. After pouring, the multi-mode electromagnetic stirring device is immediately turned on. The equipment speed is 20 r / min, and the speed ratio of revolution position to rotation position is 1:0.75. After the shear flow device runs for 20 minutes, the machine is stopped, the ingot mold is removed and disassembled, and the obtained steel ingot is forged to prepare the required specifications and dimensions. The steel ingot was preheated at 652℃ for 26 min, then quenched at 1050℃ for 9 min. It was then tempered three times, with the temperature and holding time for each tempering being 510℃×120 min, 515℃×120 min, and 512℃×120 min, respectively. After each tempering holding time, the steel ingot was air-cooled to obtain high-toughness and high-wear-resistant bearing steel.

[0037] Example 2

[0038] The chemical composition of the high-toughness and high-wear-resistant bearing steel provided in this embodiment is: C 0.85%, Si 0.33%, Mn 0.32%, Cr 4.21%, Ni 0.038%, Mo 4.38%, Al 0.061%, Nb 0.15%, V 1.15%, balance Fe; Accurately weigh 200 kg per furnace. Add the raw materials corresponding to the chemical composition of the high-toughness and high-wear-resistant bearing steel in the manner of placing large pieces near the inner wall of the crucible and small pieces near the center of the crucible. Close the furnace lid, turn on the vacuum pump, and evacuate the furnace to a vacuum level of 7.0 Pa for vacuum melting. The vacuum melting temperature is 1620℃. The vacuum melting process is as follows: set the furnace power to 110kW and apply electricity to raise the temperature. When the metal in the crucible begins to melt, increase the power to 150kW for melting. When splashing occurs, reduce the power to 60kW, turn off the vacuum pump, and simultaneously introduce argon gas into the furnace to increase the vacuum pressure to 250 Pa. After completion, molten steel is obtained. After adjusting the molten steel temperature to reach the tapping temperature of 1511℃, all the molten steel is poured into the ingot mold. The vacuum degree of pouring is 4Pa, and the pouring power is 70kW. After pouring, the multi-mode electromagnetic stirring device is immediately turned on. The equipment speed is 20 r / min, and the speed ratio of the revolution position to the rotation position is 1:0.75. After the shear flow device runs for 20 minutes, the machine is stopped, the ingot mold is removed and disassembled, and the obtained steel ingot is forged to prepare the required specifications and dimensions. The steel ingot was preheated at 654℃ for 28 min, then quenched at 1055℃ for 10 min, followed by three tempering processes. The tempering temperatures and holding times for each tempering were 512℃×120 min, 514℃×120 min, and 510℃×120 min, respectively. After each tempering holding period, the steel ingot was air-cooled to obtain high-toughness and high-wear-resistant bearing steel.

[0039] The matrix structure is mainly martensitic tempered structure.

[0040] Comparative Example 1

[0041] A company sells steel of grade M50, whose chemical composition is: C 0.87%, Si 0.23%, Mn 0.21%, Cr 4.11%, Mo 4.30%, V 1.18%, balance Fe; The steel ingots with the corresponding composition of the above steel were preheated at 652℃ for 28 min, quenched at 1058℃ for 10 min, and then tempered three times. The temperature and holding time of each tempering were 513℃×120 min, 512℃×120 min, and 510℃×120 min, respectively. After the tempering holding time was completed, the steel was air-cooled to obtain M50 steel.

[0042] Characterization and performance testing

[0043] 1) Figure 1 This is a microstructure diagram of the high-toughness, high-wear-resistant bearing steel prepared in Example 1. Figure 1 It can be seen that the matrix structure is mainly martensitic tempered structure, and contains a large number of uniformly fine carbides that are diffusely distributed.

[0044] 2) The high wear-resistant bearing steels prepared in Examples 1-2 and Comparative Example 1 were subjected to hardness testing, Charpy impact testing, and friction testing. Hardness was tested according to GB / T 230.1-2009; impact energy was tested according to GB / T 229-2020; the parameters for the friction test were: normal load 80 N, reciprocating frequency 10 Hz, test time 1800 s, stroke 900 μm, and room temperature. The test results are shown in Table 1.

[0045] Table 1. Performance test results of bearing steel in Examples 1-2 and Comparative Example 1

[0046] As shown in Table 1, the high-toughness and high-wear-resistant bearing steel of this invention has a hardness ≥62 HRC, an impact energy ≥15.08J, and a wear volume ≤3.17×10⁻⁶. 7 μm 3 The average friction coefficient is ≤0.555. The hardness, impact energy, and wear resistance of the high wear-resistant bearing steel samples prepared in Examples 1 and 2 are significantly higher than those of the M50 steel in Comparative Example 1, indicating that this method can significantly improve the hardness, toughness, and wear resistance of high wear-resistant bearing steel.

[0047] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-toughness, high-wear-resistant bearing steel, characterized in that, The chemical composition, by mass percentage, includes: C 0.78~0.88%, Si 0.30~0.35%, Mn 0.30~0.35%, Cr 3.75~4.50%, Ni 0.03~0.045%, Mo 4.30~4.70%, Al 0.040~0.070%, Nb 0.14~0.16%, V 0.90~1.25%, with the balance being Fe; The preparation method of the high-toughness and high-wear-resistant bearing steel includes the following steps: The raw materials corresponding to the chemical composition of the high wear-resistant bearing steel are mixed and vacuum melted to obtain molten steel. The molten steel is poured into a multi-mode electromagnetic stirring device and subjected to composite shear flow casting to obtain steel ingots; The steel ingot is preheated, quenched, and tempered three times in sequence to obtain high-toughness and high-wear-resistant bearing steel.

2. The high-toughness, high-wear-resistant bearing steel according to claim 1, characterized in that, The chemical composition of the high-toughness and high-wear-resistant bearing steel, by mass percentage, includes: C 0.81~0.85%, Si 0.32~0.33%, Mn 0.31~0.33%, Cr 3.85~4.21%, Ni 0.038~0.04%, Mo 4.40~4.38%, Al 0.05~0.061%, Nb 0.15~0.16%, V 0.95~1.15%, with the balance being Fe.

3. The method for preparing the high-toughness and high-wear-resistant bearing steel according to claim 1 or 2, characterized in that, Includes the following steps: The raw materials corresponding to the chemical composition of the high wear-resistant bearing steel are mixed and vacuum melted to obtain molten steel. The molten steel is poured into a multi-mode electromagnetic stirring device and subjected to composite shear flow casting to obtain steel ingots; The steel ingot is preheated, quenched, and tempered three times in sequence to obtain high-toughness and high-wear-resistant bearing steel.

4. The preparation method according to claim 3, characterized in that, The vacuum degree of the vacuum melting is 5~10Pa, and the power of the vacuum melting is 50~180kW.

5. The preparation method according to claim 3, characterized in that, The vacuum degree of the casting is 1~5Pa, and the casting power is 60~100kW.

6. The preparation method according to claim 3, characterized in that, In the composite shear flow casting step, the equipment rotation speed is 15~25 r / min, and the rotation speed ratio between the revolution position and the rotation position is 1:0.65~0.85; the composite shear flow casting time is 15~25 min.

7. The preparation method according to claim 3, characterized in that, The preheating temperature is 630℃~680℃; the preheating time is 20~40 min.

8. The preparation method according to claim 3, characterized in that, The quenching temperature is 1020~1080℃; the quenching time is 8~16 min.

9. The preparation method according to claim 3, characterized in that, In the three tempering steps, the temperature of each tempering is independently 480~540℃, and the tempering time of each tempering is independently 100~140 min.

10. The application of the high-toughness and high-wear-resistant bearing steel according to claim 1 or 2, or the high-toughness and high-wear-resistant bearing steel prepared by the preparation method according to any one of claims 3 to 9, in the aerospace field.

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