Composite heat treatment technology and equipment for improving wear resistance of parts

Abstract

The invention belongs to the technical field of composite heat treatment technologies, and particularly relates to a composite heat treatment technology and equipment for improving the wear resistance of parts, which comprises the following steps: step 1, heating the parts in a heating device to 850 DEG C, keeping the temperature for a period of time, and then carrying out water quenching; 2, after water quenching, the part is put into a heating device to be heated to 500-600 DEG C for tempering treatment, and after heat preservation is conducted for a period of time, cooling is conducted; 3, the tempered part is soaked in a salt bath containing nitrogen for nitrogen treatment; 4, after nitriding treatment, the part is put into a heating device to be heated, and low-temperature tempering treatment is conducted; through double-layer strengthening of salt bath nitriding and carbonitriding, a high-hardness protective layer is formed on the surface layer of the part, the hardness of a nitriding layer reaches 800-1200 HV, a high-hardness carbonitriding compound such as Fe (C, N) is formed on a carbonitriding layer, the thickness of the nitriding layer (the nitriding layer ranges from 0.1 mm to 0.3 mm, and the nitriding layer ranges from 0.2 mm to 0.5 mm) is controllable, the wear resistance of the part can be improved by 30-50% compared with traditional single heat treatment, and the high-frequency wear scene such as a gear and a bearing can be adapted.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite heat treatment, in particular to a composite heat treatment technology and equipment for improving the wear resistance of parts. BACKGROUND

[0002] In modern industrial production, the wear resistance of parts is a key factor affecting their service life and working performance. From the pistons and crankshafts of automobile engines to the gears, bearings in mechanical manufacturing, and wear-resistant liners in mining machinery, these parts continuously bear the effects of friction, impact, and alternating loads under complex and harsh working conditions. Taking gears as an example, during transmission, not only is there relative sliding friction between the tooth surfaces, but also contact stress due to the transmission of torque. If the wear resistance is insufficient, the tooth surfaces are prone to wear, gluing, and even peeling, leading to a decrease in transmission accuracy and frequent equipment failures. According to relevant statistics, the economic losses caused by part wear account for a significant proportion of the total industrial cost, with annual losses in the manufacturing industry alone reaching tens of billions of yuan due to premature wear of parts, equipment maintenance and replacement, and production stoppages.

[0003] Traditionally, to improve the wear resistance of parts, single heat treatment processes such as quenching, carburizing, and nitriding are commonly used. Quenching process forms martensite structure on the surface of the part through rapid cooling, significantly increasing the hardness and thus enhancing the wear resistance. However, pure quenching can cause large internal stress in the part, leading to increased brittleness, and when subjected to impact loads, the part is prone to fracture. Some complex-shaped parts may also deform severely during quenching due to uneven cooling. Carburizing and nitriding processes introduce carbon and nitrogen elements on the surface of the part to form a high-hardness permeation layer to improve wear resistance. However, carburizing has limited permeation layer depth, and subsequent quenching and tempering treatment is required to improve performance, and defects such as uneven carburizing and surface decarburization can occur during the process. Although nitriding can obtain a permeation layer with high hardness, good anti-seizure properties, and corrosion resistance, the process has a long cycle, high cost, and strict equipment requirements, and the thin nitriding layer can be easily damaged under high load and impact conditions, failing to fully utilize its wear resistance advantage.

[0004] In addition, some methods for improving wear resistance through surface coating technology, such as electroplating and thermal spraying, also face many challenges. Electroplated coatings have insufficient film-substrate adhesion in complex stress environments, and are prone to coating peeling; thermal sprayed coatings have high porosity, which not only affects the density and wear resistance of the coating, but also allows corrosive media to penetrate, accelerating the corrosion of the part substrate. Therefore, it is urgent to develop a new technology that can comprehensively improve the wear resistance of parts while considering factors such as the toughness of parts, processing cost, and process complexity. SUMMARY

[0005] The purpose of this section is to outline some aspects of the embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] In view of the problems existing in the current composite heat treatment technology and equipment for improving the wear resistance of parts, the present invention is proposed.

[0007] Therefore, the purpose of this invention is to provide a composite heat treatment technology and equipment to improve the wear resistance of parts. Through the double-layer strengthening of "salt bath nitriding + carbonitriding", a high-hardness protective layer is formed on the surface of the part - the nitriding layer has a hardness of 800-1200HV, and the carbonitriding layer forms high-hardness carbonitriding compounds such as Fe3(C,N). Moreover, the thickness of the diffusion layer (nitriding layer 0.1-0.3mm, co-diffusion layer 0.2-0.5mm) is controllable, which can improve the wear resistance of parts by 30-50% compared with traditional single heat treatment, and is suitable for high-frequency wear scenarios such as gears and bearings.

[0008] The martensitic structure formed by the initial water quenching lays the foundation for high hardness. The secondary high-temperature tempering (500-600℃) transforms the martensite into tempered sorbite, which not only retains the surface hardness but also eliminates the internal stress of water quenching and improves the core toughness (impact energy ≥40J), preventing the parts from breaking due to being "hard and brittle" and meeting the requirements of complex stress conditions.

[0009] The dense structure of the nitrided layer and carbonitriding layer can isolate external corrosive media and reduce direct metal-to-metal contact during part movement, significantly improving anti-galling properties (such as reducing the risk of "jamming" during gear meshing and bearing rolling), making it suitable for harsh environments such as humid and dusty conditions.

[0010] To address the aforementioned technical problems, according to one aspect of the present invention, the present invention provides the following technical solution: A composite heat treatment technology for improving the wear resistance of parts includes the following steps: Step 1: Place the parts in a heating device and heat them to 850°C. After holding the temperature for a period of time, perform water quenching. Step 2: After water quenching, place the parts in a heating device and heat to 500-600℃ for tempering treatment. After holding at this temperature for a period of time, cool them down. Step 3: Immerse the tempered parts in a salt bath containing nitrogen for nitrogen treatment; Step 4: After nitriding, place the parts in a heating device for heating and perform low-temperature tempering. Step 5: Place the part into the heating device and heat it, and then inject gaseous carbon and ammonia into the heating device to perform nitrocarburization on the part.

[0011] As a preferred embodiment of the composite heat treatment technology for improving the wear resistance of parts as described in this invention, the heat treatment time in step 1 is specifically the finite thickness of the part multiplied by the heating coefficient.

[0012] As a preferred embodiment of the composite heat treatment technology for improving the wear resistance of parts described in this invention, step 2 tempering is specifically high-temperature tempering, with a holding time of 30-180 min and a cooling rate of 5-10℃ / min.

[0013] As a preferred embodiment of the composite heat treatment technology for improving the wear resistance of parts described in this invention, in step 3, the tempered parts are immersed in a salt bath containing nitrogen and heated to 500-700℃.

[0014] As a preferred embodiment of the composite heat treatment technology for improving the wear resistance of parts described in this invention, the gas pressure introduced in step 5 is 20-80 MPa.

[0015] As a preferred embodiment of the present invention, a composite heat treatment device for improving the wear resistance of parts is used to perform the composite heat treatment technology for improving the wear resistance of parts as described in any one of claims 1-5, characterized in that it includes a heating unit, a water quenching unit, a salt bath unit, a heat preservation unit, a pressurizing unit, a monitoring unit, and a control unit.

[0016] As a preferred embodiment of the composite heat treatment device for improving the wear resistance of parts according to the present invention, the monitoring unit is used to monitor the temperature and pressure in the heating unit, and controls the pressurization unit and the heating unit through the control unit.

[0017] As a preferred embodiment of the composite heat treatment device for improving the wear resistance of parts according to the present invention, the water quenching unit is specifically a water quenching tank, and the salt bath unit is specifically a salt bath carburizing furnace.

[0018] Compared with the prior art, the beneficial effects of the present invention are: 1. Through the double-layer strengthening of "salt bath nitriding + carbonitriding", a high-hardness protective layer is formed on the surface of the part - the hardness of the nitriding layer reaches 800-1200HV, and the carbonitriding layer forms high-hardness carbonitriding compounds such as Fe3(C,N). Moreover, the thickness of the diffusion layer (nitriding layer 0.1-0.3mm, co-diffusion layer 0.2-0.5mm) is controllable, which can improve the wear resistance of the parts by 30-50% compared with the traditional single heat treatment, and is suitable for high-frequency wear scenarios such as gears and bearings.

[0019] 2. The martensitic structure formed by the initial water quenching lays the foundation for high hardness. The secondary high-temperature tempering (500-600℃) transforms the martensite into tempered sorbite, which not only retains the surface hardness but also eliminates the internal stress of water quenching and improves the core toughness (impact energy ≥40J), preventing the parts from breaking due to "hardness and brittleness" and meeting the requirements of complex stress conditions.

[0020] 3. The dense structure of the nitrided layer and carbonitriding layer can isolate external corrosive media and reduce direct metal-to-metal contact during part movement, significantly improving anti-galling properties (such as reducing the risk of "jamming" during gear meshing and bearing rolling), making it suitable for harsh environments such as humid and dusty conditions. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is a system block diagram of the present invention. Detailed Implementation

[0022] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0023] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0024] Secondly, the present invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.

[0025] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0026] This invention provides the following technical solution: a composite heat treatment technology to improve the wear resistance of parts. During use, through the double-layer strengthening of "salt bath nitriding + carbonitriding", a high-hardness protective layer is formed on the surface of the part - the nitriding layer has a hardness of 800-1200HV, and the carbonitriding layer forms high-hardness carbonitriding compounds such as Fe3(C,N). Moreover, the thickness of the diffusion layer (nitriding layer 0.1-0.3mm, co-diffusion layer 0.2-0.5mm) is controllable, which can improve the wear resistance of parts by 30-50% compared with traditional single heat treatment, and is suitable for high-frequency wear scenarios such as gears and bearings.

[0027] The martensitic structure formed by the initial water quenching lays the foundation for high hardness. The secondary high-temperature tempering (500-600℃) transforms the martensite into tempered sorbite, which not only retains the surface hardness but also eliminates the internal stress of water quenching and improves the core toughness (impact energy ≥40J), preventing the parts from breaking due to being "hard and brittle" and meeting the requirements of complex stress conditions.

[0028] The dense structure of the nitrided layer and carbonitriding layer can isolate external corrosive media and reduce direct metal-to-metal contact during part movement, significantly improving anti-galling properties (such as reducing the risk of "jamming" during gear meshing and bearing rolling), making it suitable for harsh environments such as humid and dusty conditions.

[0029] Figure 1 The diagram shown is a structural schematic of a first embodiment of a composite heat treatment technology for improving the wear resistance of parts according to the present invention. Please refer to [link / reference]. Figure 1 This embodiment of a composite heat treatment technology for improving the wear resistance of parts includes the following steps: Step 1: Place the parts in a heating device and heat them to 850°C. After holding the temperature for a period of time, perform water quenching. Step 2: After water quenching, place the parts in a heating device and heat to 500-600℃ for tempering treatment. After holding at this temperature for a period of time, cool them down. Step 3: Immerse the tempered parts in a salt bath containing nitrogen for nitrogen treatment; Step 4: After nitriding, place the parts in a heating device for heating and perform low-temperature tempering. Step 5: Place the part into the heating device and heat it, and then inject gaseous carbon and ammonia into the heating device to perform nitrocarburization on the part.

[0030] This invention improves the wear resistance and hardness of parts by combining a nitriding heat treatment process with a nitrogen-carbon dual-diffusion heat treatment process. The specific operating procedures are as follows; The parts are initially heated by the heating unit of a composite heat treatment device (such as a box-type resistance furnace with precise temperature control, with a temperature control accuracy of ±5℃).

[0031] Heating parameters: Slowly heat the parts to 850℃ (the heating rate is controlled at 10-15℃ / min to avoid thermal stress caused by excessive temperature difference), and then keep them warm after reaching the target temperature.

[0032] Insulation time: The calculation formula is "effective thickness of part × heating coefficient", where the heating coefficient is determined according to the material of the part (e.g., 1.5-2.0 min / mm for medium carbon steel and 2.0-2.5 min / mm for high alloy steel) to ensure uniform internal temperature of the part.

[0033] Water quenching treatment: After the heat preservation is completed, the parts are quickly transferred to the water quenching tank of the device (the water temperature is controlled at 20-30℃, and the water quality needs to be filtered to remove impurities). Rapid cooling is achieved by forced water circulation (cooling rate ≥50℃ / s), so that a uniform martensitic structure is formed on the surface and in the core of the parts, laying a high hardness foundation for subsequent processing. The device performs secondary heating and tempering through a heating unit (a vacuum furnace can be used to reduce oxidation of parts) and a water quenching unit (here, it serves as a cooling aid).

[0034] Heating parameters: Heat the part to 500-600℃ (the specific temperature is adjusted according to the required hardness of the part, such as 580-600℃ if higher toughness is required), with a heating rate of 8-12℃ / min.

[0035] Tempering treatment: High-temperature tempering process is adopted, with a holding time of 30-180 minutes (30-60 minutes for parts with a thickness ≤10mm and 60-180 minutes for parts with a thickness >10mm). The purpose is to eliminate the internal stress generated after water quenching, adjust the martensitic structure to tempered sorbite, and take into account both hardness and toughness.

[0036] Cooling control: After tempering, the cooling rate is controlled by the water quenching unit to be 5-10℃ / min (step cooling can be used, such as furnace cooling to 300℃ first and then air cooling) to avoid rapid cooling and stress generation again; The parts are nitrided using the salt bath unit of the device (which employs a sealed salt bath furnace to prevent leakage of harmful gases).

[0037] Salt bath preparation: The salt bath composition is mainly a mixture of cyanide, carbonate and nitride salts (such as NaCN, K2CO3 and NaN3 mixed in proportion), and the salt bath temperature is controlled at 500-580℃ in the molten state.

[0038] Nitriding process: The tempered parts are completely immersed in a salt bath. The nitrogen ions in the salt bath decompose into active nitrogen atoms at high temperature and continue to diffuse to the surface of the parts, forming a nitrided layer with a thickness of 0.1-0.3 mm (composed of ε phase and γ' phase).

[0039] Process objective: The nitrided layer can achieve a hardness of 800-1200HV, significantly improving the wear resistance, anti-galling, and corrosion resistance of the part surface, and the low processing temperature avoids affecting the overall performance of the part; Low-temperature stabilization is achieved through the device's heating unit (such as a pit-type tempering furnace) and insulation unit (an insulation box with constant temperature function).

[0040] Heating parameters: Reheat the parts to 150-250℃ (150-200℃ for low carbon steel, 200-250℃ for high carbon steel), with a heating rate of 5-8℃ / min.

[0041] Thermal insulation treatment: After heating, the part is transferred to the thermal insulation unit. The thermal insulation time is calculated based on "effective thickness of part × heating coefficient" (heating coefficient is 2.0-3.0 min / mm), and the overall range is controlled within 60-180 min to ensure that the internal structure of the part is fully stable.

[0042] Cooling method: After the heat preservation is completed, the parts are placed in clean air to cool naturally to room temperature (humidity of the cooling environment ≤60%) to further eliminate residual stress and stabilize dimensional accuracy; The process is accomplished collaboratively by the device's heating unit (continuous gas carburizing furnace), pressurization unit (furnace pressure control system), monitoring unit (temperature sensor, gas concentration analyzer), and control unit (PLC automatic control system).

[0043] Heating and Atmosphere Control: The heating unit heats the parts to 800-900℃ (adjusted according to the material, such as 850-880℃ for alloy structural steel). At the same time, gaseous carbon (such as propane, methane) and ammonia are introduced into the furnace chamber through the pressurization unit, controlling the carbon potential to be 0.8-1.2%, and the ratio of ammonia flow rate to carbon flow rate to be 3:1-5:1.

[0044] Diffusion mechanism: After heat treatment for 4-8 hours (adjusted according to the requirements of the diffusion layer), ammonia decomposes into active nitrogen atoms at high temperature (2NH3→3H2+2[N]), which are adsorbed onto the surface of the part together with carbon and diffuse towards the surface layer to form a carbonitriding layer (thickness 0.2-0.5mm). Among them, the diffusion of carbon can reduce the diffusion activation energy of nitrogen, promote the diffusion of nitrogen into deeper layers, and at the same time increase the hardness of the diffusion layer.

[0045] Process monitoring: The monitoring unit provides real-time feedback on furnace temperature, gas concentration, and pressure, while the control unit automatically adjusts the gas supply to ensure process stability. Ultimately, this results in the formation of a high-hardness carbonitride compound (such as Fe3(C,N)) on the surface of the parts, achieving excellent wear resistance, fatigue strength, and corrosion resistance.

[0046] Through a dual-layer strengthening process of "salt bath nitriding + carbonitriding", a high-hardness protective layer is formed on the surface of the parts. The nitriding layer has a hardness of 800-1200HV, and the carbonitriding layer forms high-hardness carbonitriding compounds such as Fe3(C,N). The thickness of the diffusion layer (nitriding layer 0.1-0.3mm, carbonitriding layer 0.2-0.5mm) is controllable, which can improve the wear resistance of the parts by 30-50% compared with traditional single heat treatment, making it suitable for high-frequency wear scenarios such as gears and bearings.

[0047] The martensitic structure formed by the initial water quenching lays the foundation for high hardness. The secondary high-temperature tempering (500-600℃) transforms the martensite into tempered sorbite, which not only retains the surface hardness but also eliminates the internal stress of water quenching and improves the core toughness (impact energy ≥40J), preventing the parts from breaking due to being "hard and brittle" and meeting the requirements of complex stress conditions.

[0048] The dense structure of the nitrided layer and carbonitriding layer can isolate external corrosive media and reduce direct metal-to-metal contact during part movement, significantly improving anti-galling properties (such as reducing the risk of "jamming" during gear meshing and bearing rolling), making it suitable for harsh environments such as humid and dusty conditions.

[0049] The above heat treatment process requires the use of a composite heat treatment device to improve the wear resistance of parts. The composite heat treatment technology for improving the wear resistance of parts specifically includes: a heating unit, a water quenching unit, a salt bath unit, a heat preservation unit, a pressurizing unit, a monitoring unit, and a control unit. The monitoring unit is used to monitor the temperature and pressure in the heating unit and to control the pressurizing unit and the heating unit through the control unit. The water quenching unit is specifically a water quenching tank, and the salt bath unit is specifically a salt bath carburizing furnace. Heating Unit: As the core heating module of the device, it undertakes the heating tasks in the entire process (initial heating in step 1, secondary heating in step 2, low-temperature heating in step 4, and carbonitriding heating in step 5). It adopts a modular design to adapt to different process requirements: including box-type resistance furnace (used for 850℃ heating in step 1, with a temperature control accuracy of ±5℃, the furnace cavity volume is designed according to the part size, and the inner wall is made of high-temperature resistant ceramic fiber to reduce heat loss), vacuum heating furnace (used for 500-600℃ tempering in step 2, with a vacuum degree ≤10⁻³Pa to avoid oxidation of the part surface), pit-type tempering furnace (used for 150-250℃ low-temperature heating in step 4, with a furnace temperature uniformity ≤±3℃), and continuous gas carburizing furnace (used for 800-900℃ carbonitriding in step 5, the furnace body is divided into a preheating zone, a carburizing zone, and a diffusion zone, which can achieve continuous temperature control).

[0050] Water quenching unit: The main body is a stainless steel water quenching tank (volume 500-1000L, designed according to the batch of parts), with a built-in spiral water circulation system (flow rate adjustable, maximum circulation rate 20L / min), water temperature sensor (monitoring range 0-100℃, accuracy ±1℃) and cooling coil (external chiller, which can stabilize the water temperature at 20-30℃).

[0051] Salt bath unit: The furnace body is made of high-temperature resistant alloy material (can withstand temperatures above 600℃), with a built-in salt bath tank (capacity 300-500L), electric heating tube (power 50-100kW, heating uniformity ±5℃) and stirring device (to ensure uniform salt bath composition); equipped with a salt bath recovery system (to reduce waste residue emissions) and a waste gas treatment device (to treat cyanide tail gas through an alkaline spray tower).

[0052] Insulation unit: a constant temperature insulation box (volume 1-3m³), with the inner wall lined with high-purity alumina insulation cotton (insulation performance ≥0.03W / (m・K)), built-in electric heating wire (power 5-10kW) and circulating fan (to ensure temperature uniformity within the box ±2℃); equipped with humidity sensor (monitoring range 30-80%RH) and dehumidification device.

[0053] The pressurization unit consists of a gas storage tank (for storing propane / methane and ammonia respectively), a precision pressure reducing valve (for controlling gas pressure 0.1-0.5MPa), a flow meter (accuracy ±2%FS), and an in-furnace pressure regulating valve; it is connected to the furnace cavity of the continuous gas carburizing furnace and the timing of gas introduction is controlled by a pipeline solenoid valve.

[0054] Monitoring Units: Temperature Monitoring: Real-time temperature of the heating unit, salt bath unit, and insulation unit is monitored via thermocouples (measurement range 0-1200℃, accuracy ±1℃); Pressure Monitoring: Pressure inside the gas carburizing furnace and gas pressure in the pressurization unit are monitored via pressure sensors (measurement range 0-1MPa, accuracy ±0.5%FS); Atmosphere Monitoring: CO and NH3 concentrations inside the furnace are detected in real time via an infrared gas analyzer (accuracy ±1%), carbon potential is calculated and fed back; Data Transmission: Monitoring data is transmitted to the control unit in real time via an industrial bus (such as Modbus protocol), with a sampling frequency of 1 time / second.

[0055] Control unit: Receives data from the monitoring unit and automatically adjusts the power of the heating unit (to maintain the target temperature) and the gas flow rate of the pressurization unit (to control the carbon-nitrogen ratio). The built-in process database can automatically match parameters for each step (such as heating coefficient and holding time) based on the material of the parts (such as medium carbon steel and high alloy steel). Realize unit linkage control (such as automatically triggering the robotic arm to transfer the parts to the water quenching unit after the heating unit finishes its heat preservation).

[0056] Although the present invention has been described above with reference to embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, as long as there is no structural conflict, the features in the disclosed embodiments can be combined with each other in any manner. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A composite heat treatment technology for improving the wear resistance of parts, characterized in that: Includes the following steps: Step 1: Place the parts in a heating device and heat them to 850°C. After holding the temperature for a period of time, perform water quenching. Step 2: After water quenching, place the parts in a heating device and heat to 500-600℃ for tempering treatment. After holding at this temperature for a period of time, cool them down. Step 3: Immerse the tempered parts in a salt bath containing nitrogen for nitrogen treatment; Step 4: After nitriding, place the parts in a heating device for heating and perform low-temperature tempering. Step 5: Place the part into the heating device and heat it, and then inject gaseous carbon and ammonia into the heating device to perform nitrocarburization on the part.

2. The composite heat treatment technology for improving the wear resistance of parts according to claim 1, characterized in that: The specific heat preservation time for step 1 is the finite thickness of the part multiplied by the heating coefficient.

3. The composite heat treatment technology for improving the wear resistance of parts according to claim 1, characterized in that: Step 2 tempering specifically involves high-temperature tempering, with a holding time of 30-180 minutes and a cooling rate of 5-10℃ / min.

4. The composite heat treatment technology for improving the wear resistance of parts according to claim 1, characterized in that: Step 3: Immerse the tempered parts in a salt bath containing nitrogen and heat them to 500-700℃.

5. The composite heat treatment technology for improving the wear resistance of parts according to claim 1, characterized in that: The gas pressure in step 5 is 20-80 MPa.

6. A composite heat treatment apparatus for improving the wear resistance of parts, used to perform the composite heat treatment technology for improving the wear resistance of parts as described in any one of claims 1-5, characterized in that: It includes a heating unit, a water quenching unit, a salt bath unit, a heat preservation unit, a pressurization unit, a monitoring unit, and a control unit.

7. The composite heat treatment apparatus for improving the wear resistance of parts according to claim 6, characterized in that: The monitoring unit is used to monitor the temperature and pressure inside the heating unit, and controls the pressurization unit and the heating unit through the control unit.

8. The composite heat treatment apparatus for improving the wear resistance of parts according to claim 6, characterized in that: The water quenching unit is specifically a water quenching tank, and the salt bath unit is specifically a salt bath carburizing furnace.

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