Gradient martensite-bainite complex-phase structure construction forming manufacturing method for high-carbon steel bearing under extreme working conditions

Abstract

The invention provides a gradient martensite-bainite complex-phase structure construction forming manufacturing method for a high-carbon steel bearing under an extreme working condition, and relates to the technical field of bearing manufacturing. The method comprises the steps that the target carbonitriding temperature is determined according to the first target carbon potential of a workpiece to be machined, the target carbonitriding time is determined according to the target carbonitriding layer depth, and carbonitriding is conducted on the rolled workpiece to be machined according to the target carbonitriding temperature and the target carbonitriding time; the target austenitizing temperature is determined according to the second target carbon potential of the carbonitriding furnace, the to-be-machined workpiece subjected to carbonitriding treatment is put into a high-temperature box-type furnace, and austenitizing is conducted on the to-be-machined workpiece subjected to carbonitriding treatment according to the target austenitizing temperature; and the target isothermal quenching temperature is determined according to the second target carbon potential in the carbonitriding furnace, and the austenitized to-be-machined workpiece is immersed into a low-temperature salt bath furnace according to the target isothermal quenching temperature for isothermal quenching. The wear resistance, strength and toughness of the bearing can be improved.

Description

Technical Field

[0001] The present invention relates to the field of bearing manufacturing technology, and in particular to a method for constructing and manufacturing a gradient Mapei complex phase structure of a high-carbon steel bearing under extreme working conditions. Background Art

[0002] Bearings are key components for mechanical equipment to transmit motion and carry force, and their performance directly affects the performance and life of the main machine. Bearings are mainly composed of rings, rolling elements and cages, among which rings are the core components of bearings. It is of great significance to regulate the organizational state of bearing rings through forming manufacturing to obtain high-performance bearing rings. High-end equipment bearings usually work under extreme conditions such as high temperature, high speed and heavy load, requiring bearing rings to have high wear resistance, high strength and high toughness at the same time. How to obtain bearing rings that are both wear-resistant and high-strength and tough is a key problem that needs to be solved urgently for high-end equipment bearings facing extreme service conditions. At present, high-carbon steel bearings have been using traditional martensitic heat treatment processes. The obtained martensitic structure has high strength but low toughness, and the surface and core performance are consistent, which cannot achieve high wear resistance and impact resistance synergistic matching. Therefore, facing the extreme service conditions of high-end equipment, it is urgent to develop a forming and manufacturing method with strong surface and toughness inside. Summary of the invention

[0003] The purpose of the present invention is to address the deficiencies in the above-mentioned prior art and provide a method for constructing and manufacturing a gradient Mapei multiphase structure of a high-carbon steel bearing under extreme working conditions, so as to achieve a synergistic improvement in the wear resistance, strength and toughness of the bearing.

[0004] To achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows:

[0005] In the first aspect, an embodiment of the present application provides a method for constructing and forming a gradient Mapei complex phase structure of a high-carbon steel bearing under extreme working conditions, including: rolling a workpiece to be processed according to a target size; determining a target carbonitriding temperature according to a first target carbon potential in the workpiece to be processed, determining a target carbonitriding time according to a target carbonitriding layer depth, and carbonitriding the rolled workpiece to be processed according to the target carbonitriding temperature and the target carbonitriding time; determining a target austenitizing temperature according to a second target carbon potential in a carbonitriding furnace, placing the workpiece to be processed after the carbonitriding treatment into a box-type high-temperature furnace, and austenitizing the workpiece to be processed after the carbonitriding treatment according to the target austenitizing temperature; determining a target isothermal quenching temperature according to the second target carbon potential in the carbonitriding furnace, immersing the austenitized workpiece to be processed in a low-temperature salt bath furnace for isothermal quenching according to the target isothermal quenching temperature, so as to construct an extreme working condition high-carbon steel bearing with a Mapei complex phase gradient structure.

[0006] In one embodiment, the rolling of the workpiece to be processed according to the target size includes: determining the target feed speed of the pressure roller corresponding to the workpiece to be processed according to the relationship between the inner diameter and outer diameter of the workpiece, the driving roller rotation speed of the rolling mill, the driving roller radius, the friction angle between the rolling roller and the workpiece, and the pressure roller radius and the pressure roller feed speed; determining the target rolling ratio corresponding to the workpiece to be processed based on the principle of constant rolling volume and the relationship between the inner diameter of the workpiece, the pressure roller radius, the driving roller radius and the rolling ratio; and rolling the workpiece to be processed according to the target size, the target feed speed and the target rolling ratio.

[0007] In one embodiment, after rolling the workpiece to be processed, the method further comprises: inspecting the rolled workpiece to be processed according to the target size to determine whether the rolled workpiece to be processed meets the requirements of the finished product.

[0008] In one embodiment, determining the target carbonitriding temperature according to the first target carbon potential in the workpiece to be processed includes: determining the relationship between the pressure of carbon dioxide, the pressure of carbon monoxide, the carbonitriding temperature and the carbon activity in the carbonitriding furnace in the gas introduced into the carbonitriding furnace; and determining the target carbonitriding temperature corresponding to the first target carbon potential in the workpiece to be processed according to the relationship between the carbon potential in the workpiece, the carbon activity in the carbonitriding furnace and the carbonitriding temperature.

[0009] In one embodiment, determining the target carbonitriding time according to the target carbonitriding layer depth includes: determining the target carbonitriding time corresponding to the target carbonitriding layer depth according to the relationship between the carbonitriding temperature, the carbonitriding time and the carbonitriding layer depth.

[0010] In one embodiment, determining the target austenitizing temperature according to the second target carbon potential in the carbonitriding furnace includes: determining the target austenitizing temperature corresponding to the second target carbon potential in the carbonitriding furnace according to the relationship between the initial transformation temperature of austenitizing, the final temperature of austenite formation, and the carbon potential in the carbonitriding furnace and the austenitizing temperature.

[0011] In one embodiment, the relationship between the austenitizing initial transformation temperature, the final austenite formation temperature, the carbon potential in the carbonitriding furnace and the austenitizing temperature is shown in the following formula:

[0012] T A =T AC3 +(K A -C P )T AC1

[0013] Among them, T AIndicates the austenitizing temperature; T AC1 Indicates the initial transformation temperature of austenitization; T AC3 Indicates the final temperature of austenite formation; K A Indicates the austenitizing temperature correction coefficient, ranging from 0.25 to 0.28; C P Indicates the carbon potential in the carbonitriding furnace.

[0014] In one embodiment, determining the target isothermal quenching temperature according to the second target carbon potential in the carbonitriding furnace includes: determining the target isothermal quenching temperature corresponding to the second target carbon potential in the carbonitriding furnace according to the relationship between the initial transformation temperature of martensite, the outer diameter and the inner diameter of the workpiece, the carbon potential in the carbonitriding furnace and the isothermal quenching temperature.

[0015] In one embodiment, the relationship between the initial martensite transformation temperature, the outer diameter and inner diameter of the workpiece, the carbon potential in the carbonitriding furnace and the isothermal quenching temperature is shown in the following formula:

[0016]

[0017] Among them, T B Indicates the isothermal quenching temperature; K B Indicates the isothermal quenching temperature correction coefficient, the value range is 0.05~0.1; C P represents the carbon potential in the carbonitriding furnace; d represents the inner diameter of the workpiece; D represents the outer diameter of the workpiece; T MS represents the initial martensite transformation temperature.

[0018] In one embodiment, after immersing the austenitized workpiece to be processed into a low-temperature salt bath furnace for isothermal quenching according to the target isothermal quenching temperature, the method further includes: placing the isothermal quenched workpiece to be processed into a high-temperature tempering furnace, and tempering the isothermal quenched workpiece according to preset tempering parameters.

[0019] The beneficial effects of the present application are as follows: (1) through the active coordinated movement of the driving roller / pressure roller, the dual-drive deformation controls the metal flow rate and deformation amount of the bearing rolling surface, thereby realizing ultrafine grain deformation of the bearing rolling surface; (2) through the carbonitriding preheat treatment, nitrogen-containing martensite and carbonitride compounds are introduced into the surface layer of the bearing ring to improve its surface wear resistance; the high concentration of carbon and nitrogen on the surface reduces the critical cooling rate of the steel, increases the residual austenite content on the surface of the bearing ring, reduces the origin-type spalling on the surface of the bearing ring, and further enhances the surface wear resistance; the compressive stress introduced into the co-diffusion layer after carbonitriding can effectively improve the wear resistance and fatigue performance of the bearing ring; (3) according to the surface carbon potential and nitrogen potential, the austenitization and isothermal quenching temperatures of the Mapei duplex heat treatment are determined, thereby introducing different contents of bainite on the bearing surface and core (usually more in the core), and under the genetic effect of rolling deformation and carbonitriding heat treatment, a nano-sized Mapei duplex gradient structure with surface wear resistance / high toughness in the core is finally constructed, thereby realizing a synergistic improvement in the wear resistance, strength and toughness of the bearing. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 A schematic diagram of a process for constructing and manufacturing a gradient Mapei multiphase structure of a high-carbon steel bearing under extreme working conditions provided in an embodiment of the present application;

[0022] Figure 2 A schematic diagram of a process for constructing and manufacturing a gradient Mapei multiphase structure of a high-carbon steel bearing under extreme working conditions provided in an embodiment of the present application;

[0023] Figure 3 A schematic diagram of a process for constructing and manufacturing a gradient Mapei multiphase structure of a high-carbon steel bearing under extreme working conditions provided in an embodiment of the present application;

[0024] Figure 4 A schematic diagram of a process for constructing and manufacturing a gradient Mapei multiphase structure of a high-carbon steel bearing under extreme working conditions provided in an embodiment of the present application;

[0025] Figure 5 A schematic diagram of the bearing surface structure in a method for constructing and manufacturing a gradient Mapei multiphase structure of a high-carbon steel bearing under extreme working conditions provided in an embodiment of the present application;

[0026] Figure 6A schematic diagram of the bearing core structure in a method for constructing and forming a gradient Mapei multiphase structure of a high-carbon steel bearing under extreme working conditions provided in an embodiment of the present application;

[0027] Figure 7 A schematic diagram of the relationship between bearing hardness and distance from the surface in a method for constructing and manufacturing a gradient Mapei complex phase structure of a high-carbon steel bearing under extreme working conditions provided in an embodiment of the present application. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0029] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0030] In the description of the present application, it should be noted that if the terms "upper", "lower", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, or is the orientation or position relationship in which the product of the application is usually placed when used. It is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0031] In addition, the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0032] It should be noted that, in the absence of conflict, the features in the embodiments of the present application may be combined with each other.

[0033] Figure 1A schematic diagram of a process for constructing and forming a gradient Mapei multiphase structure of a high-carbon steel bearing under extreme working conditions provided in an embodiment of the present application; Figure 1 As shown, the method includes:

[0034] Step 110: rolling the workpiece to be processed according to the target size.

[0035] The target size is the final size of the workpiece to be processed and rolled; in actual operation, the target size includes the target diameter and the target height.

[0036] The workpiece to be processed refers to the bearing ring. This is because, although the bearing is composed of a ring, rolling elements and a cage, the ring is the core component of the bearing. Therefore, it is of great significance to control the organizational state of the bearing ring through forming manufacturing to obtain a high-performance bearing ring.

[0037] When the ring is rolled, the main motor drives the driving roller to rotate, and the friction between the driving roller and the blank is used to pull the blank in and continuously press it. At the same time, the friction between the ring blank and the pressure roller drives the pressure roller to rotate. Driven by the feeding system, the pressure roller moves radially at a certain feeding speed, and the center distance between the pressure roller and the driving roller gradually decreases until the deformation ends.

[0038] During the rolling process, the pressure roller feed speed and pressing ratio need to be controlled; specifically, Figure 2 As shown, the above step 110 may further include the following steps 210 to 230:

[0039] Step 210, determine the target feed speed of the pressure roller corresponding to the workpiece to be processed based on the inner diameter, outer diameter of the workpiece, the driving roller speed of the rolling mill, the driving roller radius, the friction angle between the rolling roller and the workpiece, and the relationship between the pressure roller radius and the pressure roller feed speed.

[0040] The relationship between the inner diameter and outer diameter of the workpiece, the driving roller speed of the rolling mill, the driving roller radius, the friction angle between the roller and the workpiece, the pressure roller radius and the pressure roller feed speed is shown in the following formula (1):

[0041]

[0042] Among them, v represents the feed speed of the pressure roller; n represents the speed of the driving roller; β represents the friction angle between the workpiece and the roller; R represents the outer diameter of the workpiece; r represents the inner diameter of the workpiece; R1 represents the radius of the driving roller; and R2 represents the radius of the pressure roller.

[0043] In actual operation, the inner diameter and outer diameter of the workpiece to be processed are substituted into the above formula (1) to obtain the target feed speed of the pressure roller corresponding to the workpiece to be processed.

[0044] Step 220: Based on the rolling volume invariance principle and according to the relationship between the inner diameter of the workpiece, the pressure roller radius, the driving roller radius and the rolling ratio, determine the target rolling ratio corresponding to the workpiece to be processed.

[0045] The relationship between the inner diameter of the workpiece, the pressure roller radius, the driving roller radius and the rolling ratio is shown in the following formula (2):

[0046]

[0047] Where, k represents the rolling ratio; k max represents the maximum rolling ratio; r0 represents the inner diameter of the workpiece; R1 represents the radius of the driving roller; and R2 represents the radius of the pressure roller.

[0048] Step 230: rolling the workpiece according to the target size, the target feed speed and the target rolling ratio.

[0049] In actual operation, the rolling mill is controlled with the above-mentioned target feed speed and target rolling ratio to roll the workpiece to be processed. When the diameter and height of the workpiece to be processed reach the target diameter and target height in the target size, the pressure roller stops the feeding movement and the rolling process ends.

[0050] In actual operation, before rolling the workpiece, the workpiece can be pre-treated for rolling. Specifically, the surface of the workpiece can be cleaned, for example, the surface of the workpiece can be washed and degreased, and then the workpiece after rolling pre-treatment can be put into the rolling mill for rolling.

[0051] In actual operation, after the workpiece to be processed is rolled, the workpiece to be processed after rolling can be inspected to determine whether the workpiece to be processed after rolling meets the requirements of the finished product; specifically, after the workpiece to be processed is rolled, the method further includes:

[0052] The workpiece to be processed after rolling is inspected according to the target size to determine whether the workpiece to be processed after rolling meets the requirements of the finished product.

[0053] Among them, in actual operation, an error range can be set for the target size based on experience or by looking up literature. When the workpiece to be processed after rolling is within the error range, it is determined that the workpiece to be processed after rolling meets the finished product requirements; otherwise, it does not meet the finished product requirements.

[0054] Step 120, determining a target carbonitriding temperature according to a first target carbon potential in the workpiece to be processed, determining a target carbonitriding time according to a target carbonitriding layer depth, and performing carbonitriding on the rolled workpiece to be processed according to the target carbonitriding temperature and the target carbonitriding time.

[0055] The first target carbon potential in the workpiece to be processed is the carbon potential in the workpiece to be processed.

[0056] The target carbonitriding temperature can be determined based on the relationship between carbon activity and carbon potential in the workpiece; specifically, Figure 3 As shown, the above step 120 may further include the following steps 310 to 330:

[0057] Step 310, determining the relationship between the pressure of carbon dioxide, the pressure of carbon monoxide in the gas introduced into the carbonitriding furnace, the carbonitriding temperature and the carbon activity in the carbonitriding furnace.

[0058] The relationship between the pressure of carbon dioxide, the pressure of carbon monoxide, the carbonitriding temperature and the carbon activity in the carbonitriding furnace is as shown in the following formula (3):

[0059]

[0060] Among them, a c represents carbon activity; K represents equilibrium constant; P CO Indicates the pressure of carbon monoxide in the gas introduced into the carbonitriding furnace; It indicates the pressure of carbon dioxide in the gas introduced into the carbonitriding furnace; T indicates the carbonitriding temperature.

[0061] Step 320: Determine a target carbonitriding temperature corresponding to a first target carbon potential in the workpiece to be processed according to the relationship between the carbon potential in the workpiece, the carbon activity in the carbonitriding furnace and the carbonitriding temperature.

[0062] Among them, the relationship between the carbon potential in the workpiece, the carbon activity in the carbonitriding furnace and the carbonitriding temperature is shown in the following formula (4):

[0063]

[0064] Among them, a c represents carbon activity; T represents carbonitriding temperature; [%C] represents carbon potential in the workpiece.

[0065] The target carbonitriding time can be determined according to the relationship between the carbonitriding temperature, the carbonitriding time and the depth of the carbonitriding layer; specifically, determining the target carbonitriding time according to the target carbonitriding layer depth includes:

[0066] According to the relationship among the carbonitriding temperature, the carbonitriding time and the depth of the carbonitriding layer, the target carbonitriding time corresponding to the target carbonitriding layer depth is determined.

[0067] The relationship between the carbonitriding temperature, the carbonitriding time and the depth of the carbonitriding layer is shown in the following formula (5):

[0068]

[0069] Wherein, d represents the depth of the carbonitriding layer; t represents the carbonitriding time; and T represents the carbonitriding temperature.

[0070] In actual operation, before carbonitriding the rolled workpiece to be processed, the rolled workpiece to be processed can be subjected to carbonitriding pretreatment. Specifically, the surface of the rolled workpiece to be processed can be cleaned, for example, the surface of the rolled workpiece to be processed can be cleaned, degreased, and rusted. The rolled workpiece to be processed can also be placed in a carbonitriding furnace and the air in the carbonitriding furnace can be exhausted as soon as possible to prevent oxidation of the workpiece to be processed.

[0071] Step 130 , determining a target austenitizing temperature according to a second target carbon potential in the carbonitriding furnace, placing the workpiece to be processed after the carbonitriding treatment into a box-type high-temperature furnace, and austenitizing the workpiece to be processed after the carbonitriding treatment according to the target austenitizing temperature.

[0072] The second target carbon potential in the carbonitriding furnace is the carbon potential in the carbonitriding furnace.

[0073] The target austenitizing temperature can be determined according to the relationship between the initial transformation temperature of austenitizing, the final temperature of austenite formation, the carbon potential in the carbonitriding furnace and the austenitizing temperature; specifically, the target austenitizing temperature is determined according to the second target carbon potential in the carbonitriding furnace, including:

[0074] According to the relationship between the initial transformation temperature of austenitizing, the final temperature of austenite formation, the carbon potential in the carbonitriding furnace and the austenitizing temperature, the target austenitizing temperature corresponding to the second target carbon potential in the carbonitriding furnace is determined.

[0075] Among them, the relationship between the initial transformation temperature of austenitizing, the final temperature of austenite formation, the carbon potential in the carbonitriding furnace and the austenitizing temperature is shown in the following formula (6):

[0076] T A =T AC3 +(K A -C P )T AC1 (6)

[0077] Among them, T A Indicates the austenitizing temperature; T AC1 Indicates the initial transformation temperature of austenitization; T AC3 Indicates the final temperature of austenite formation; K A Indicates the austenitizing temperature correction coefficient, ranging from 0.25 to 0.28; C P Indicates the carbon potential in the carbonitriding furnace.

[0078] Step 140, determine the target isothermal quenching temperature according to the second target carbon potential in the carbonitriding furnace, immerse the austenitized workpiece in a low-temperature salt bath furnace for isothermal quenching according to the target isothermal quenching temperature, and construct an extreme working condition high carbon steel bearing with Mapei complex phase gradient structure.

[0079] The target austempering temperature can be determined according to the relationship between the initial transformation temperature of martensite, the outer diameter and inner diameter of the workpiece, the carbon potential in the carbonitriding furnace and the austempering temperature; specifically, determining the target austempering temperature according to the second target carbon potential in the carbonitriding furnace includes:

[0080] According to the relationship between the initial transformation temperature of martensite, the outer diameter and inner diameter of the workpiece, the carbon potential in the carbonitriding furnace and the isothermal quenching temperature, the target isothermal quenching temperature corresponding to the second target carbon potential in the carbonitriding furnace is determined.

[0081] Among them, the relationship between the initial transformation temperature of martensite, the outer diameter and inner diameter of the workpiece, the carbon potential in the carbonitriding furnace and the isothermal quenching temperature is shown in the following formula (7):

[0082]

[0083] Among them, T B Indicates the isothermal quenching temperature; K B Indicates the isothermal quenching temperature correction coefficient, the value range is 0.05~0.1; C P represents the carbon potential in the carbonitriding furnace; d represents the inner diameter of the workpiece; D represents the outer diameter of the workpiece; T MS represents the initial martensite transformation temperature.

[0084] In actual operation, before austenitizing the workpiece after carbonitriding treatment, the workpiece to be processed after carbonitriding treatment can be subjected to Mapei multiphase heat treatment pretreatment. Specifically, the workpiece to be processed after carbonitriding treatment can be preheated, for example: the workpiece to be processed after carbonitriding treatment is placed in an oven and kept warm at a preheating temperature of 200-350°C for 5-10 minutes, so that the workpiece to be processed is evenly heated during the austenitizing process.

[0085] In actual operation, after rolling the workpiece to be processed, the workpiece to be processed can be tempered to reduce the brittleness of the steel part, reduce or eliminate internal stress, prevent deformation or cracking of the workpiece, stabilize the size of the workpiece, and obtain the required mechanical properties; specifically, after immersing the austenitized workpiece to be processed in a low-temperature salt bath furnace for isothermal quenching according to the target isothermal quenching temperature, the extreme working condition high carbon steel bearing gradient Mapei complex phase structure forming manufacturing method provided in the embodiment of the present application also includes:

[0086] The workpiece to be processed after isothermal quenching is placed in a high-temperature tempering furnace, and the workpiece to be processed after isothermal quenching is tempered according to preset tempering parameters.

[0087] In actual operation, when the workpiece material to be processed is high-temperature bearing steel, the tempering is cyclically tempered three times at a tempering temperature of 535℃~550℃; when the workpiece material to be processed is ordinary bearing steel, the tempering is performed at a tempering temperature of 150~160℃ for 2h.

[0088] The embodiment of the present application provides a method for constructing, forming and manufacturing a gradient Mapei complex phase structure of a high-carbon steel bearing under extreme working conditions. First, the workpiece to be processed is rolled according to the target size; secondly, the target carbonitriding temperature is determined according to the first target carbon potential in the workpiece to be processed, and the target carbonitriding time is determined according to the target carbonitriding layer depth, and the rolled workpiece to be processed is carbonitrided according to the target carbonitriding temperature and the target carbonitriding time; thirdly, the target austenitizing temperature is determined according to the second target carbon potential in the carbonitriding furnace, and the workpiece to be processed after the carbonitriding treatment is placed in a box-type high-temperature furnace and austenitized according to the target austenitizing temperature; finally, the target isothermal quenching temperature is determined according to the second target carbon potential in the carbonitriding furnace, and the austenitized workpiece to be processed is immersed in a low-temperature salt bath furnace for isothermal quenching according to the target isothermal quenching temperature, so as to construct an extreme working condition high-carbon steel bearing with Mapei complex phase gradient structure. In this way, (1) through the active coordinated movement of the drive roller / pressure roller, the dual-drive deformation controls the metal flow rate and deformation of the bearing rolling surface, and realizes ultrafine grain deformation of the bearing rolling surface; (2) nitrogen-containing martensite and carbonitriding compounds are introduced into the surface of the bearing ring through carbonitriding preheat treatment to improve its surface wear resistance; the high concentration of carbon and nitrogen on the surface reduces the critical cooling rate of steel, increases the residual austenite content on the surface of the bearing ring, reduces the origin-type spalling on the surface of the bearing ring, and further enhances the surface wear resistance; the introduced compressive stress in the co-diffusion layer after carbonitriding can effectively improve the wear resistance and fatigue performance of the bearing ring; (3) according to the surface carbon potential and nitrogen potential, the austenitization and isothermal quenching temperatures of the Mapei duplex heat treatment are determined, so as to introduce different contents of bainite on the surface and core of the bearing (usually more in the core), and under the genetic effect of rolling deformation and carbonitriding heat treatment, a nano-sized Mapei duplex gradient structure with surface wear resistance and high toughness in the core is finally constructed, achieving a synergistic improvement in the wear resistance, strength and toughness of the bearing.

[0089] After introducing the extreme working condition high carbon steel bearing gradient Mapei complex phase structure forming and manufacturing method of the exemplary embodiment of the present disclosure, next, Figure 4 As shown, the test example is described:

[0090] For a certain type of bearing made of GCr15 (outer diameter 90mm, inner diameter 75mm), the Mapei multiphase gradient structure forming manufacturing method is implemented in the following steps:

[0091] Step 1: Strain state controlled rolling forming

[0092] After the bearing ring blank is cleaned and degreased, it is placed on the rolling mill for rolling. The driving roller speed is 146r / min, the pressure roller feed speed is 1mm / s, and the rolling ratio is 1.35. When the diameter and height of the workpiece reach the predetermined size, the pressure roller stops feeding and the rolling process ends. Check whether the diameter and height of the workpiece meet the requirements of the finished product;

[0093] Step 2: Carbonitriding pre-heat treatment

[0094] Clean, degrease and rust the workpiece surface. After the workpiece is loaded into the furnace, exhaust the air in the furnace as soon as possible. The exhaust time is 40 minutes. Perform strong infiltration treatment on the workpiece, maintain the furnace temperature at 850℃, keep warm for 150 minutes, control the carbon potential in the furnace at 1.3%, and the ammonia volume at 1.5NL / min. Perform diffusion treatment on the workpiece, continue to maintain the furnace temperature at 850℃, the diffusion time is 60 minutes of the carbonitriding time, the carbon potential in the furnace is 1.0%, and the ammonia volume is 1.5NL / min;

[0095] Step 3: Mapei heat treatment

[0096] Place the bearing ring in an oven and preheat it at 300°C for 5 minutes. Then place the bearing ring in a box-type high-temperature furnace for austenitization at 850°C and 22 minutes. After austenitization, immerse the bearing ring in a low-temperature salt bath furnace and isothermally quench at 240°C for 20 minutes. After completion, quickly remove the bearing ring and quench it into a large oil tank. After the salt on the surface of the bearing ring condenses and crystallizes, take it out and wash it in warm water and dry it. Finally, place the bearing ring in a tempering furnace and temper it at 160°C for 2 hours.

[0097] The microstructure of the bearing ring obtained in the above embodiment is observed, and it is found that the bearing surface (such as Figure 5 as shown) and the core (as Figure 6 The mechanical properties of the bearing rings were tested and it was found that the hardness of the GCr15 bearing rings of the embodiment of the present invention decreased from the surface to the core (as shown in FIG. Figure 7As shown); the wear rate is reduced by 52% compared with the wear rate of the conventional heat-treated bearing rings; the impact energy of the conventionally manufactured bearing rings is 17J / cm2, the impact strength of the bearing rings is 62J / cm2, and the wear resistance and impact toughness of the bearing rings are synergistically improved. This shows that the Mapei multiphase gradient structure constructed by the extreme working condition high carbon steel bearing gradient Mapei multiphase structure forming and manufacturing method provided in the embodiment of the present application can achieve high wear resistance / high toughness of the bearings and meet the service requirements of the bearings under extreme working conditions.

[0098] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for forming and manufacturing a gradient Mapei multiphase structure of a high carbon steel bearing under extreme working conditions, characterized in that: include: Rolling the workpiece to be processed according to the target size; Determining a target carbonitriding temperature according to a first target carbon potential in the workpiece to be processed, determining a target carbonitriding time according to a target carbonitriding layer depth, and performing carbonitriding on the workpiece to be processed after rolling according to the target carbonitriding temperature and the target carbonitriding time; Determining a target austenitizing temperature according to a second target carbon potential in the carbonitriding furnace, placing the workpiece to be processed after the carbonitriding treatment into a box-type high-temperature furnace and austenitizing the workpiece to be processed after the carbonitriding treatment according to the target austenitizing temperature; The target isothermal quenching temperature is determined according to the second target carbon potential in the carbonitriding furnace, and the austenitized workpiece is immersed in a low-temperature salt bath furnace for isothermal quenching according to the target isothermal quenching temperature to construct an extreme working condition high-carbon steel bearing with Mapei complex phase gradient structure.

2. The method according to claim 1, characterized in that The step of rolling the workpiece to be processed according to the target size comprises: Determine the target feed speed of the pressure roller corresponding to the workpiece to be processed according to the relationship between the inner diameter and outer diameter of the workpiece, the rotation speed of the driving roller of the rolling mill, the radius of the driving roller, the friction angle between the rolling roller and the workpiece, and the radius of the pressure roller and the feed speed of the pressure roller; Based on the principle of constant rolling volume, according to the relationship between the inner diameter of the workpiece, the radius of the pressure roller, the radius of the driving roller and the rolling ratio, the target rolling ratio corresponding to the workpiece to be processed is determined; The workpiece to be processed is rolled according to the target size, the target feed speed and the target rolling ratio.

3. The method according to claim 2, characterized in that After rolling the workpiece to be processed, the method further comprises: The workpiece to be processed after rolling is inspected according to the target size to determine whether the workpiece to be processed after rolling meets the requirements of the finished product.

4. The method according to claim 1, characterized in that The step of determining a target carbonitriding temperature according to a first target carbon potential in the workpiece to be processed comprises: Determining the relationship between the pressure of carbon dioxide, the pressure of carbon monoxide, the carbonitriding temperature and the carbon activity in the carbonitriding furnace; The target carbonitriding temperature corresponding to the first target carbon potential in the workpiece to be processed is determined according to the relationship between the carbon potential in the workpiece, the carbon activity in the carbonitriding furnace and the carbonitriding temperature.

5. The method according to claim 1, characterized in that Determining the target carbonitriding time according to the target carbonitriding layer depth includes: The target carbonitriding time corresponding to the target carbonitriding layer depth is determined according to the relationship between the carbonitriding temperature, the carbonitriding time and the carbonitriding layer depth.

6. The method according to claim 1, characterized in that Determining the target austenitizing temperature according to the second target carbon potential in the carbonitriding furnace includes: The target austenitizing temperature corresponding to the second target carbon potential in the carbonitriding furnace is determined according to the relationship between the initial transformation temperature of austenitizing, the final temperature of austenite formation, the carbon potential in the carbonitriding furnace and the austenitizing temperature.

7. The method according to claim 6, characterized in that The relationship between the initial transformation temperature of austenitizing, the final temperature of austenite formation, the carbon potential in the carbonitriding furnace and the austenitizing temperature is shown in the following formula: T A =T AC3 +(K A -C P )T AC1 Among them, T A Indicates the austenitizing temperature; T AC1 Indicates the initial transformation temperature of austenitization; T AC3 Indicates the final temperature of austenite formation; K A Indicates the austenitizing temperature correction coefficient, ranging from 0.25 to 0.28; C P Indicates the carbon potential in the carbonitriding furnace.

8. The method according to claim 1, characterized in that Determining the target austempering temperature according to the second target carbon potential in the carbonitriding furnace comprises: The target isothermal quenching temperature corresponding to the second target carbon potential in the carbonitriding furnace is determined according to the relationship between the martensite initial transformation temperature, the outer diameter and the inner diameter of the workpiece, the carbon potential in the carbonitriding furnace and the isothermal quenching temperature.

9. The method according to claim 8, characterized in that The relationship between the initial martensite transformation temperature, the outer diameter and inner diameter of the workpiece, the carbon potential in the carbonitriding furnace and the isothermal quenching temperature is shown in the following formula: Among them, T B Indicates the isothermal quenching temperature; K B Indicates the isothermal quenching temperature correction coefficient, the value range is 0.05~0.1; C P represents the carbon potential in the carbonitriding furnace; d represents the inner diameter of the workpiece; D represents the outer diameter of the workpiece; T MS represents the initial martensite transformation temperature.

10. The method according to claim 1, characterized in that After immersing the austenitized workpiece to be processed into a low-temperature salt bath furnace for isothermal quenching according to the target isothermal quenching temperature, the method further includes: The workpiece to be processed after isothermal quenching is placed in a high-temperature tempering furnace, and the workpiece to be processed after isothermal quenching is tempered according to preset tempering parameters.

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