Carburizing heat treatment method for metal surface hardness modification

Abstract

The invention discloses a carburizing heat treatment method for metal surface hardness modification. The carburizing heat treatment method comprises the following steps of S1, material preparation, S2, carburizing agent adding, S3, carburizing heat treatment, S4, equipment detection, S5, sample detection and S6, product packaging. A worker pretreats steel, grinds the steel and grinds an oxide layer on the surface of the steel, then the isopropyl-ketone is conveniently used for cleaning subsequently, and oil stains, dirt and other impurities on the surface of the steel can be rapidly dissolved and removed through the isopropyl-ketone, so that the surface of the steel becomes clean and smooth; according to the steel carburizing heat treatment device, subsequent carburizing treatment on steel is facilitated, so that the quality of carburizing heat treatment on the steel is improved, then the steel is dried, residual liquid is prevented from influencing heat treatment work on the steel, and then the steel is preheated, so that subsequent heat treatment work is facilitated, and the working efficiency of heat treatment is improved.

Description

Technical Field

[0001] The invention relates to the technical field of carburizing heat treatment, in particular to a carburizing heat treatment method for modifying the hardness of a metal surface. Background Art

[0002] With the development of industry, the application of metal materials is becoming more and more extensive. However, the nature of metal materials makes them prone to wear and fatigue in certain applications. In order to solve these problems, people have been looking for methods to improve the performance of metal materials. Among them, carburizing heat treatment is a common method. Therefore, "the original heat treatment method for pretreatment of metals has poor effect, and when carburizing metals, the effect of adding carburizing agents is poor", which is specifically manifested in the following aspects:

[0003] (1) When heat treating metals, there will be oxide layers and impurities on the metal surface, which will affect the heat treatment of the metal, thereby making the subsequent carburizing heat treatment of the metal difficult and reducing the quality of the metal carburizing heat treatment; (2) The carburizing agent is dripped into the furnace using the traditional drop method, that is, the container containing the carburizing agent is placed at a high place and dripped into the furnace at a low place by potential energy. Although this method is effective, it is inconvenient to operate. The container filled with carburizing agent needs to be placed at a high place and the carburizing agent needs to be pumped to the container at a high place, resulting in messy equipment placement and easy trouble in adding carburizing agent; (3) After carburizing the metal, the hardness of the metal needs to be tested. Normally, only simple hardness tests can be performed on the metal, so it is impossible to perform in-depth tests on the metal and the quality of metal carburization cannot be detected. Summary of the invention

[0004] The purpose of the present invention is to provide a carburizing heat treatment method for modifying the surface hardness of a metal, so as to solve the problems of the current carburizing heat treatment method mentioned in the above background technology: (1) when the metal is heat treated, there will be an oxide layer and impurities on the metal surface, which will affect the heat treatment of the metal, thereby making the subsequent carburizing heat treatment of the metal difficult and reducing the quality of the carburizing heat treatment of the metal; (2) the carburizing drops are dripped into the furnace by the traditional drop method, that is, the container containing the carburizing drops is placed at a high place and dripped into the furnace at a low place by potential energy. Although this method is effective, it is inconvenient to operate. The container filled with the carburizing agent needs to be placed at a high place and the carburizing agent needs to be pumped to the container at a high place, resulting in a messy placement of the equipment and making it easy to add the carburizing agent. (3) After the metal is carburized, the hardness of the metal needs to be tested. Normally, only a simple hardness test can be performed on the metal, so that the metal cannot be deeply tested and the quality of the metal carburization cannot be detected.

[0005] To achieve the above object, the present invention provides the following technical solution: a carburizing heat treatment method for modifying the surface hardness of a metal, the treatment method comprising the following steps:

[0006] S1. Material preparation

[0007] 1. Purchase materials: ① Select metal material steel; ② Determine the purchase quantity; 2. Material processing: ① Material cleaning; ② Material grinding; ③ Isopropyl acetone cleaning; ④ Material drying; 3. Preheat the steel: preheat the steel at 200℃.

[0008] S2. Add carburizing agent

[0009] 1. Check the carburizing furnace, ① clean the equipment, ② check the instrument, ③ set the heat treatment parameters, time, temperature and pressure, 2. Add carburizing agent, ① connect the carburizing agent tube to the carburizing furnace, ② check whether the connection is tight, ③ use liquid nitrogen to pressurize the carburizing agent.

[0010] S3, carburizing heat treatment

[0011] 1. Heat treatment: ① Perform strong penetration on the steel at 940℃ for 5h, ② Perform high-temperature diffusion on the steel at 910℃ for 3h, ③ Perform low-temperature diffusion on the steel at 830℃ for 1.5h, 2. Intermediate stage treatment: ① Evenly heat the steel at 750℃ for 1h, ② Oil cooling, ③ Perform low-temperature tempering on the steel at 175℃ for 2.5h, 3. Material cooling: ① Air cooling, ② Heat recovery.

[0012] S4. Equipment detection

[0013] 1. Parameter debugging, ① temperature, pressure and time detection and recording, ② temperature, pressure and time adjustment, 2. Safety protection, ① alarm system, ② emergency stop of the device.

[0014] S5. Sample testing

[0015] 1. Appearance inspection: ① length inspection, ② thickness inspection, ③ appearance defect inspection; 2. Hardness inspection: ① metallographic microstructure analysis of samples using a metallographic microscope, ② testing using a Rockwell hardness tester, ③ thin layer analysis of samples using X-ray diffraction, transmission electron microscopy, and scanning electron microscopy.

[0016] S6. Product packaging

[0017] 1. Clean the products, 2. Package, stack and store the products, 3. Transport the products.

[0018] Preferably, the carburizing chemical reaction formula is: CH4=2H2+[C], 2CO=CO2+[C], CO+H2=H2O+[C], CO=[C]+1 / 2O2.

[0019] Preferably, the calculation formula between the carburizing depth and the carburizing time is a=802.6√e / 10(3720 / E) to the power.

[0020] Preferably, a is the carburizing layer depth, in mm, e is the carburizing time, in h, and E is the carburizing temperature, in °C.

[0021] Preferably, the heating time calculation formula is T=KxW(2-14), T is the workpiece temperature time min, K is the comprehensive factor min / mm, and W is the geometric index.

[0022] Preferably, when the shape is a cylinder, W=(0.167-0.25)xD; when the shape is a plate, W=(0.167-0.5)xD.

[0023] Preferably, D in the formula is the effective size of the workpiece, and its unit is mm.

[0024] Preferably, the carburizing furnace carbon potential correction calculation formula is Δμ=clog(t / t0)+c1S+c2C+c3M.

[0025] Preferably, in the carburizing furnace carbon potential correction calculation formula, Δμ represents the carbon potential correction value, c, c1, c2, c3 are constants, t is the carburizing time, t0 is the reference time, S is the surface area, C is the carbon content, and M is the quenching cooling waste heat.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention allows staff to determine to purchase metal material steel, and then determine the quantity of the purchased steel. Then the staff pre-treats the steel, grinds the steel, grinds the oxide layer on the surface, and then facilitates subsequent cleaning with isopropyl acetone. Then the isopropyl acetone can quickly dissolve and remove oil, dirt and other impurities on the surface of the steel, so that the surface of the steel becomes clean and smooth, which is convenient for subsequent carburizing treatment of the steel, thereby improving the quality of carburizing heat treatment of the steel. Then the steel is dried to prevent residual liquid from affecting the heat treatment of the steel. Then the steel is preheated, thereby facilitating subsequent heat treatment and improving the work efficiency of the heat treatment.

[0028] The present invention uses liquid nitrogen to pressurize the carburizing agent and transport it. The carburizing agent is placed in a sealed 20-liter container. The container is provided with a pressure gauge, a liquid level gauge, a needle valve and other valve parts. The nitrogen pressure released from the liquid nitrogen cylinder is used to pressurize the container. The carburizing agent in the container is transported to the furnace through a pipeline due to the pressure. It is only necessary to separate the nitrogen and pressurize two or more containers respectively. Since nitrogen is a neutral gas with a high purity (above 99.8%), it generally has no harmful effect on the carburizing agent. The consumption of liquid nitrogen is theoretically calculated to be 1000 liters of carburizing droplets. The agent only needs to release about 2 kg of liquid nitrogen. Nitrogen is only consumed when the container is replenished with drops of agent and the container is depressurized and the exhaust valve of the container is opened. Therefore, the amount of liquid nitrogen is very economical. The pressure required for the container depends on the requirements and distance of conveying the carburizing agent, and is usually maintained at 0.3-0.5 kg / 2 cm. To avoid nitrogen entering the carburizing furnace, the carburizing drops should be replenished when only 1 / 3 of the container is left, thereby avoiding the use of the drop method to add carburizing agent to the carburizing furnace, and improving the convenience and quality of adding carburizing agent to the carburizing furnace.

[0029] The present invention randomly checks the products, then detects the appearance of the steel, then measures the length and thickness of the steel with a tape measure, then has the tester check the appearance of the sample to see if there is any damage, and then performs metallographic microstructure analysis on the sample. The metallographic microstructure analysis usually includes the steps of cutting, grinding, corroding, degreasing, and polishing the sample, and finally observes and analyzes the organizational structure of the sample under a metallographic microscope, and then performs hardness testing on the sample with a Rockwell hardness tester. Finally, thin layer analysis is an analysis technology that uses X-ray diffraction, transmission electron microscope and scanning electron microscope equipment to analyze the surface properties and chemical composition of the sample, forms a thin film on the surface of the material, and then uses various technical means to analyze the thin film, so as to obtain information about the material, and through a variety of detection methods, can comprehensively analyze the hardness component organizational structure of the steel, so as to obtain comprehensive information, and ensure that the carburizing quality of the steel meets the national standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a flow chart of the carburizing heat treatment of the present invention;

[0031] Figure 2 It is a stage diagram of carburizing heat treatment in the process of the present invention;

[0032] Figure 3 It is the carburizing furnace debugging code logic diagram of the present invention;

[0033] Figure 4 This is a partial code logic diagram for the carburizing furnace operation of the present invention. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions 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. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Embodiment 1:

[0036] Please refer to the figure, a carburizing heat treatment method for modifying the hardness of a metal surface, the treatment method comprises the following steps:

[0037] S1. Material preparation

[0038] 1. Purchase materials, ① select metal material steel, ② determine the purchase quantity, 2. Material processing, ① material cleaning, ② material grinding, ③ isopropyl acetone cleaning, ④ material drying, 3. Steel preheating, use 200℃ to preheat the steel. At the beginning of the work, the staff determines to purchase metal material steel, and then determines the quantity of steel to be purchased. Then the staff pre-processes the steel, grinds the steel, grinds the surface oxide layer, and then facilitates the subsequent cleaning with isopropyl acetone. Then isopropyl acetone can quickly dissolve and remove oil, dirt and other impurities on the surface of the steel, making the steel surface clean and smooth, which is convenient for the subsequent carburizing treatment of the steel, thereby improving the quality of the carburizing heat treatment of the steel. Then the steel is dried to prevent the residual liquid from affecting the heat treatment of the steel, and then the steel is preheated, which facilitates the subsequent heat treatment and improves the work efficiency of the heat treatment;

[0039] S2. Add carburizing agent

[0040] 1. Check the carburizing furnace, ① clean the equipment, ② check the instruments, ③ set the heat treatment parameters, time, temperature and pressure, 2. Add carburizing agent, ① connect the carburizing agent tube to the carburizing furnace, ② check whether the connection is tight, ③ use liquid nitrogen to pressurize the carburizing agent. The staff will clean the carburizing furnace at the beginning to prevent dust inside from affecting the carburizing work. Then the staff will check the instruments on the carburizing furnace to check whether they can work normally. Then connect the equipment containing the carburizing agent to the carburizing furnace, and then use liquid nitrogen to pressurize the carburizing agent. The carburizing agent is placed in a sealed 20-liter container with a pressure gauge, liquid level gauge, needle valve and other valve parts on the container. The nitrogen pressure released by the liquid nitrogen cylinder is used to pressurize the container. The carburizing agent in the container is under pressure, that is, it flows through the pipeline to For transportation in the furnace, it is only necessary to divide the nitrogen and pressurize it into two or more containers respectively. Since nitrogen is a neutral gas with high purity (above 99.8%), it generally has no harmful effect on the carburizing agent. Theoretically, the consumption of liquid nitrogen is that only about 2 kg of liquid nitrogen is released for every 1000 liters of carburizing drops. Nitrogen is only consumed when the container is replenished with drops, the container must be depressurized, and the exhaust valve of the container is opened. Therefore, the amount of liquid nitrogen is very economical. The pressure required for the container depends on the requirements and distance of transporting the carburizing agent, and is usually maintained at 0.3-0.5 kg / 2 cm. To avoid nitrogen entering the carburizing furnace, the carburizing drops should be replenished when only 1 / 3 of the container is left, thereby avoiding the use of the drop method to add carburizing agent to the carburizing furnace, improving the convenience and quality of adding carburizing agent to the carburizing furnace.

[0041] S3, carburizing heat treatment

[0042] 1. Heat treatment: ① Carry out strong penetration of steel at 940℃ for 5h, ② Carry out high temperature diffusion of steel at 910℃ for 3h, ③ Carry out low temperature diffusion of steel at 830℃ for 1.5h, 2. Intermediate stage treatment: ① Heating the steel at 750℃ for 1h, ② Oil cooling, ③ Tempering the steel at 175℃ for 2.5h, 3. Material cooling: ① Air cooling, ② Heat recovery. Carbon steel is heat treated in a carburizing furnace. At the beginning of the work, the temperature is 940℃. The steel is subjected to strong infiltration for 5 hours, then high-temperature diffusion at 910°C for 3 hours, then low-temperature diffusion at 830°C for 1.5 hours, then uniform heating at 750°C for 1 hour, then cold treatment, then low-temperature tempering at 175°C for 2.5 hours, finally cooling the steel and recovering excess heat through a heat exchanger.

[0043] S4. Equipment detection

[0044] 1. Parameter debugging, ① temperature, pressure and time detection and recording, ② temperature, pressure and time adjustment, 2. Safety protection, ① alarm system, ② emergency stop of the device, use the detection equipment to adjust, record and detect the temperature, pressure and heating time of the carburizing furnace. When any parameter of temperature, pressure and time exceeds or falls below the setting, the alarm system will sound an alarm to remind the staff to check and adjust the carburizing furnace. Then, when the temperature of the carburizing furnace exceeds the set temperature of 500℃, the device will be stopped urgently and the staff will be notified to cool down the equipment urgently to prevent danger.

[0045] S5. Sample testing

[0046] 1. Appearance inspection: ① length inspection, ② thickness inspection, ③ appearance defect inspection; 2. Hardness inspection: ① metallographic microscope is used to analyze the sample's metallographic microstructure; ② Rockwell hardness tester is used for testing; ③ X-ray diffraction, transmission electron microscope and scanning electron microscope are used for thin layer analysis of the sample. After the carburizing work of the steel is completed, the product is randomly inspected, and then the steel appearance is inspected. Then the length and thickness of the steel are measured by tape measure, and then the appearance of the sample is checked by the tester to see if there is any damage. Then the sample is subjected to metallographic microstructure analysis. Metallographic microstructure analysis usually includes cutting, Grinding, corrosion, degreasing, and polishing steps, and finally observing and analyzing the sample's organizational structure under a metallographic microscope, and then testing the hardness of the sample with a Rockwell hardness tester. Finally, thin layer analysis is an analytical technology that uses X-ray diffraction, transmission electron microscopy and scanning electron microscopy equipment to analyze the surface properties and chemical composition of the sample. A thin film is formed on the surface of the material, and then various technical means are used to analyze this film to obtain information about the material. Through a variety of detection methods, the hardness component and organizational structure of the steel can be comprehensively analyzed, so as to obtain comprehensive information and ensure that the carburizing quality of the steel meets national standards.

[0047] S6. Product packaging

[0048] 1. Clean the products; 2. Package, stack and store the products; 3. Transport the products. After the carburizing work on the steel is completed, the surface of the products is cleaned, and then the products are packaged and stacked. The products are then transported to designated locations for use by users as needed.

[0049] In this embodiment: carburizing chemical reaction formula: CH4=2H2+[C], 2CO=CO2+[C], CO+H2=H2O+[C], CO=[C]+1 / 2O2.

[0050] In this embodiment, the calculation formula between the carburizing depth and the carburizing time is a=802.6√e / 10(3720 / E) to the power.

[0051] In this embodiment: a is the carburizing layer depth, unit is mm, e is the carburizing time, unit is h, and E is the carburizing temperature, unit is °C.

[0052] In this embodiment: the heating time calculation formula is T=KxW (2-14), T is the workpiece temperature time min, K is the comprehensive factor min / mm, and W is the geometric index.

[0053] In this embodiment: when the shape is a cylinder, W=(0.167-0.25)xD; when the shape is a plate, W=(0.167-0.5)xD.

[0054] In this embodiment: D in the formula is the effective size of the workpiece, and its unit is mm.

[0055] In this embodiment: the carburizing furnace carbon potential correction calculation formula Δμ=clog(t / t0)+c1S+c2C+c3M.

[0056] In this embodiment: Δμ in the carburizing furnace carbon potential correction calculation formula represents the carbon potential correction value, c, c1, c2, c3 are constants, t is the carburizing time, t0 is the reference time, S is the surface area, C is the carbon content, and M is the quenching cooling waste heat.

[0057] Embodiment 2:

[0058] As shown in the figure, different from the first embodiment, the present embodiment is a carburizing heat treatment method for modifying the hardness of a metal surface, and its management method includes the following steps:

[0059] S1. After cleaning the surface of the metal workpiece, the non-working surface is treated for anti-seepage.

[0060] S2. Place the metal workpiece treated in S1 into a carburizing furnace, raise the temperature to 930°C, introduce a carburizing agent into the carburizing furnace to form a carburizing atmosphere, and control the carbon potential according to the depth of the carburized layer. First, control the carbon potential CP to 1.1%, and maintain the carburizing time at 1.5 hours, then control the carbon potential CP to 0.8%, and maintain the carburizing time at 1 hour.

[0061] S3, cooling the carburized metal workpiece in S2 to 760°C, keeping it at that temperature for 4 hours, then raising the temperature to 830°C, keeping it at that temperature for 1 hour, then raising the temperature to 900°C, keeping it at that temperature for 1 hour.

[0062] S4. Cool the metal workpiece heated in S3 to 860°C again and keep it at that temperature for 1 hour. Put it into 72°C oil to cool it quickly and quench it.

[0063] S5. The quenched metal workpiece is subjected to the first tempering in an environment of 520°C for 2 hours, and then subjected to the second tempering in an environment of 230°C for 1 hour, and then taken out of the furnace and air-cooled to room temperature.

[0064] In summary: compared with Example 2, this Example 1 conducts random inspections on the products, and then detects the appearance of the steel, then measures the length and thickness of the steel with a tape measure, and then the tester checks the appearance of the sample to see if there is any damage, and then performs metallographic microstructure analysis on the sample. Metallographic microstructure analysis usually includes sample cutting, grinding, corrosion, degreasing, and polishing steps, and finally observes and analyzes the organizational structure of the sample under a metallographic microscope, and then performs hardness testing on the sample with a Rockwell hardness tester. Finally, thin layer analysis is an analysis technology that uses X-ray diffraction, transmission electron microscopy and scanning electron microscopy equipment to analyze the surface properties and chemical composition of the sample. A thin film is formed on the surface of the material, and then the thin film is analyzed using various technical means to obtain information about the material. Through a variety of detection methods, the hardness component and organizational structure of the steel can be comprehensively analyzed, so that comprehensive information can be obtained to ensure that the carburizing quality of the steel meets national standards.

[0065] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0066] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A carburizing heat treatment method for modifying the surface hardness of a metal, characterized in that the treatment method comprises the following steps: S1. Material preparation 1. Purchase materials, ① select metal material steel, ② determine the purchase quantity, 2. Material processing, ① material cleaning, ② material grinding, ③ isopropyl acetone cleaning, ④ material drying, 3. Preheat the steel, preheat the steel at 200℃; S2. Add carburizing agent 1. Check the carburizing furnace, ① clean the equipment, ② check the instrument, ③ set the heat treatment parameters, time, temperature and pressure, 2. Add carburizing agent, ① connect the carburizing agent tube to the carburizing furnace, ② check whether the connection is tight, ③ use liquid nitrogen to pressurize the carburizing agent; S3, carburizing heat treatment 1. Heat treatment: ① strong penetration of steel at 940℃ for 5h, ② high temperature diffusion of steel at 910℃ for 3h, ③ low temperature diffusion of steel at 830℃ for 1.5h, 2. Intermediate stage treatment: ① uniform heating of steel at 750℃ for 1h, ② oil cooling, ③ low temperature tempering of steel at 175℃ for 2.5h, 3. Material cooling: ① air cooling, ② heat recovery; S4. Equipment detection 1. Parameter debugging, ① temperature, pressure and time detection and recording, ② temperature, pressure and time adjustment, 2. Safety protection, ① alarm system, ② emergency stop of the device; S5. Sample testing 1. Appearance inspection: ① length inspection, ② thickness inspection, ③ appearance defect inspection; 2. Hardness inspection: ① metallographic microstructure analysis of samples using metallographic microscope, ② Rockwell hardness tester, ③ thin layer analysis of samples using X-ray diffraction, transmission electron microscope and scanning electron microscope; S6. Product packaging 1. Clean the products, 2. Package, stack and store the products, 3. Transport the products.

2. The carburizing heat treatment method for modifying the surface hardness of a metal according to claim 1, characterized in that: The carburizing chemical reaction formula is: CH4=2H2+[C], 2CO=CO2+[C], CO+H2=H2O+[C], CO=[C]+1 / 2O2.

3. The carburizing heat treatment method for modifying the surface hardness of a metal according to claim 1, characterized in that: The calculation formula between the carburizing depth and the carburizing time is a=802.6√e / 10(3720 / E) to the power.

4. The carburizing heat treatment method for modifying the surface hardness of a metal according to claim 3, characterized in that: Wherein a is the carburizing layer depth, unit is mm, e is the carburizing time, unit is h, and E is the carburizing temperature, unit is °C.

5. The carburizing heat treatment method for modifying the surface hardness of a metal according to claim 1, characterized in that: The heating time calculation formula is T=KxW (2-14), T is the workpiece temperature time min, K is the comprehensive factor min / mm, and W is the geometric index.

6. The carburizing heat treatment method for modifying the surface hardness of a metal according to claim 5, characterized in that: When the shape is a cylinder, W=(0.167-0.25)xD; when the shape is a plate, W=(0.167-0.5)xD.

7. The carburizing heat treatment method for modifying the surface hardness of a metal according to claim 6, characterized in that: In the above formula, D is the effective size of the workpiece, and its unit is mm.

8. The carburizing heat treatment method for modifying the surface hardness of a metal according to claim 1, characterized in that: The carburizing furnace carbon potential correction calculation formula Δμ=clog(t / t0)+c1S+c2C+c3M.

9. The carburizing heat treatment method for modifying the surface hardness of a metal according to claim 8, characterized in that: In the carburizing furnace carbon potential correction calculation formula, Δμ represents the carbon potential correction value, c, c1, c2, c3 are constants, t is the carburizing time, t0 is the reference time, S is the surface area, C is the carbon content, and M is the quenching cooling waste heat.

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