Gas nitriding method for 1Cr11Ni23Ti3MoB shaft part

Abstract

The invention discloses a gas nitriding method for a 1Cr11Ni23Ti3MoB shaft part. The gas nitriding method comprises the following steps: step 1, pretreating the 1Cr11Ni23Ti3MoB part; 2, drying the quartz sand, mixing ammonium chloride and the quartz sand, and charging; step 3, charging the parts into a furnace; 4, nitrogen is introduced into the furnace, and exhaust is conducted; 5, the temperature of the nitriding furnace is increased to 400 DEG C or above, and ammonia gas is introduced into the furnace in two paths; 6, the temperature of the nitriding furnace is increased to 540 + / -5 DEG C, and heat preservation is conducted for 30 + / -1 h; detecting whether the decomposition rate of ammonia in the furnace is 30-50% or not; and 8, the temperature of the nitriding furnace is increased to 570 + / -5 DEG C, heat preservation is conducted for 25 + / -1 h, whether the ammonia decomposition rate in the furnace ranges from 60% to 80% or not is detected, then introduction of ammonia gas into the furnace is stopped, nitrogen is introduced into the furnace according to the speed of 2 m < 3 > to 3 m < 3 > / h, the 1Cr11Ni23Ti3MoB shaft part is cooled to 150 DEG C or below along with the path, introduction of nitrogen is stopped, and the part is discharged out of the furnace.

Description

Technical Field

[0001] The invention relates to the field of surface modification heat treatment of metal materials, and in particular to a gas nitriding method for 1Cr11Ni23Ti3MoB shaft parts. The gas nitriding process is used to increase the surface hardness of 1Cr11Ni23Ti3MoB high temperature elastic alloy shaft parts and improve the wear resistance of the parts. Background Art

[0002] 1Cr11Ni23Ti3MoB is an austenitic precipitation hardening stainless steel with high high temperature strength and high high temperature elasticity. It is mainly used to manufacture pins, shafts and other components that work in high temperature environments. In order to improve the wear resistance of parts, nitriding treatment is required on the surface of the parts, and the hardness of the nitriding layer is required to be greater than 800HV 0.2 , nitriding layer thickness ≥ 0.09mm.

[0003] Since Ni and N elements cannot form alloy nitriding products during the nitriding process, parts that are partially nitrided are generally treated with nickel plating to prevent nitriding. There are many alloy elements in 1Cr11Ni23Ti3MoB materials, and nitriding treatment is very difficult. The industry is not yet mature in the research of gas nitriding technology for 1Cr11Ni23Ti3MoB materials, and gas nitriding technology is still blank in the aviation industry system, and there are no relevant technical parameters. Summary of the invention

[0004] The purpose of the present invention is to provide a gas nitriding method for 1Cr11Ni23Ti3MoB shaft parts, which is used to increase the surface hardness of 1Cr11Ni23Ti3MoB shaft parts and improve the wear resistance of the parts.

[0005] Technical solution:

[0006] The gas nitriding method of 1Cr11Ni23Ti3MoB shaft parts comprises the following steps:

[0007] Step 1: pre-treat the 1Cr11Ni23Ti3MoB shaft parts, and clean the surface of the 1Cr11Ni23Ti3MoB shaft parts after pre-treatment;

[0008] Step 2: Dry the quartz sand, mix the ammonium chloride and quartz sand in a certain proportion, put them into the catalytic box, and load them into the furnace together with the parts;

[0009] Step 3: 1Cr11Ni23Ti3MoB shaft parts are loaded into the furnace;

[0010] Step 4: Introduce nitrogen into the furnace and exhaust it;

[0011] Step 5: The temperature of the nitriding furnace is raised to above 400°C, and ammonia is introduced into the furnace in two ways, one of which is constant ammonia with a flow rate of 5L / min to 15 / min, and the other is controlled ammonia with a flow rate of 5L / min;

[0012] Step 6: The nitriding furnace is heated to 540°C ± 5°C, and the ammonia decomposition rate in the furnace is detected to be between 30% and 50%. If so, step 7 is performed, otherwise the constant ammonia flow rate in step 5 is adjusted until the ammonia decomposition rate in the furnace is between 30% and 50%.

[0013] Step 7: 1Cr11Ni23Ti3MoB shaft parts are kept at 540℃±5℃ for 30h±1h;

[0014] Step 8: The nitriding furnace is heated to 570°C ± 5°C, and the ammonia decomposition rate in the furnace is detected to be between 60% and 80%. If so, step 9 is performed, otherwise the constant ammonia flow rate in step 5 is adjusted until the ammonia decomposition rate in the furnace is between 60% and 80%.

[0015] Step 9: 1Cr11Ni23Ti3MoB shaft parts are kept at 570℃±5℃ for 25h±1h;

[0016] Step 10: Stop introducing ammonia into the furnace and 3 ~3m 3 / h nitrogen is introduced into the furnace, and the temperature of 1Cr11Ni23Ti3MoB shaft parts is cooled down to below 150℃ along the way. Then the introduction of nitrogen is stopped and the parts are taken out of the furnace.

[0017] Further, in step 1, the 1Cr11Ni23Ti3MoB shaft parts are pretreated, including solution treatment and aging treatment;

[0018] Solution treatment: put 1Cr11Ni23Ti3MoB shaft parts into a box-type electric furnace, heat to 1010±10℃, keep warm for 2-3h, and oil cool;

[0019] Aging treatment: put 1Cr11Ni23Ti3MoB shaft parts into a box-type electric furnace, heat it to 750-780℃, keep it warm for 16-16.5h; cool it down to 620-660℃ with the furnace, keep it warm for 10-16h, and air cool it.

[0020] Further, in step 2, quartz sand is dried at a temperature of 280°C to 300°C and a holding time of 20min to 30min. After drying, the mixture is cooled to room temperature. Ammonium chloride and quartz sand are mixed in a ratio of 50g:150g, placed in a catalytic box, and loaded into the furnace together with the parts.

[0021] Further, in step 3, the 1Cr11Ni23Ti3MoB shaft parts are placed flat on the external teeth of the furnace loading tooling, wherein the furnace loading tooling is a plate-like structure with external teeth.

[0022] Further, step 4: nitrogen is introduced into the furnace and exhausted; the nitrogen flow rate is 2-3m 3 / h, exhaust time 50min~70min, after exhausting, stop introducing nitrogen and start heating.

[0023] Further, step 6 specifically includes the following steps:

[0024] Step 6.1 Open the valve of the nitriding furnace test gas inlet and the test gas flow meter knob switch to ensure that the test gas flow meter value is 0.2L~0.5L / min;

[0025] Step 6.2: Adjust the opening of the constant ammonia valve to ensure that the pressure difference between the furnace and the atmosphere is within the range of 200 kPa to 1000 kPa;

[0026] Step 6.3: Fine-tune the constant ammonia and control the flow rate of ammonia to ensure that the ammonia decomposition rate is maintained at 30% to 50%.

[0027] Furthermore, in step 7, the 1Cr11Ni23Ti3MoB shaft parts are kept at 540°C±5°C for 30h±1h, while fine-tuning the constant ammonia and controlling the flow rate of ammonia to ensure that the ammonia decomposition rate is maintained at 40%.

[0028] Further, step 8 specifically includes the following steps:

[0029] Step 8.1 Open the valve of the nitriding furnace test gas inlet and the test gas flow meter knob switch to ensure that the test gas flow meter value is 0.2L~0.5L / min;

[0030] Step 8.2: Adjust the opening of the constant ammonia valve to ensure that the pressure difference between the furnace and the atmosphere is within the range of 200 kPa to 1000 kPa;

[0031] Step 8.3 fine-tunes the constant ammonia and controls the flow rate of ammonia to ensure that the ammonia decomposition rate is maintained at 60% to 80%.

[0032] Furthermore, in step 9, the 1Cr11Ni23Ti3MoB shaft parts are kept at 570°C±5°C for 25h±1h, while fine-tuning the constant ammonia and controlling the flow rate of ammonia to ensure that the ammonia decomposition rate is maintained at 70%.

[0033] Furthermore, the method further comprises step 11, cleaning the 1Cr11Ni23Ti3MoB shaft parts with clean kerosene and drying them; and step 12, inserting the single 1Cr11Ni23Ti3MoB shaft parts into a foam board for packaging to prevent collision.

[0034] Beneficial effects:

[0035] A gas nitriding method for 1Cr11Ni23Ti3MoB shaft parts is proposed. The surface hardness of 1Cr11Ni23Ti3MoB high temperature elastic alloy shaft parts is increased through the gas nitriding process, and the wear resistance of the parts is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention. It is obvious that 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 work.

[0037] Figure 1 It is the solid solution process curve diagram of the present invention;

[0038] Figure 2 It is the aging process curve diagram of the present invention;

[0039] Figure 3 A top view of the furnace loading tooling of the present invention;

[0040] Figure 4 It is a side view of the furnace loading tooling of the present invention;

[0041] Figure 5 This is a partial enlarged view of the furnace loading tooling of the present invention;

[0042] Figure 6 This is a rendering of the effect of clamping parts in the furnace loading tooling of the present invention. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution 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 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 making creative work are within the scope of protection of the present invention.

[0044] The features and illustrative embodiments of various aspects of the present invention will be described in detail below. In the detailed description below, many specific details are proposed to provide a comprehensive understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is only to provide a better understanding of the present invention by illustrating examples of the present invention. The present invention is by no means limited to any specific settings and methods proposed below, but covers any improvements, replacements and modifications of structures, methods, devices without departing from the spirit of the present invention. In the accompanying drawings and the following description, known structures and technologies are not shown to avoid unnecessary ambiguity in the present invention.

[0045] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other, and the embodiments can refer to and quote each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0046] One embodiment of the present invention is to provide a gas nitriding method for 1Cr11Ni23Ti3MoB shaft parts, including solid solution and aging preparatory heat treatment before rough machining of 1Cr11Ni23Ti3MoB shaft parts, and nitriding treatment after fine machining. Nitriding adopts RN2-50-80 type pit nitriding furnace, the furnace temperature uniformity is ±5℃, and an atmosphere circulation device is provided in the furnace to ensure uniform atmosphere. Before nitriding, quartz sand is dried at 280℃~300℃, and the insulation time is 20min~30min. After drying, it is cooled to room temperature, and then the catalytic agent ammonium chloride and quartz sand are evenly mixed in a mass ratio of 1:3, and then put into the catalytic box and loaded into the furnace together with the parts.

[0047] The operator inserts the parts into the tooling, and the parts are placed vertically with a spacing of 7mm between the parts. After the parts are put into the furnace, the furnace door is closed. The main valve, pressure reducer, and needle valve on the nitrogen pipeline are opened to supply nitrogen to the gas distribution cabinet. Nitrogen is introduced for exhaust, and the furnace pressure is controlled in a positive pressure state. The nitrogen bypass manual valve in the distribution cabinet is opened, and the exhaust flow rate is 2 to 3m 3 / h; pressure display value 2~3. Start operation after exhaust time 50min~70min. Press the fan start button, turn on the exhaust gas and ignite it, then start heating.

[0048] The operator sets the nitriding process parameters: the first stage nitriding temperature: 540℃±5℃, holding time 30h±1h, decomposition rate 30%~50%, ammonia decomposition rate setting value 40%. The second stage nitriding degree: 570℃±5℃, holding time 25h±1h, decomposition rate 60%~80%, ammonia decomposition rate setting value 70%. When the furnace temperature reaches 400℃, open the ammonia main valve and the needle valve on the bus, adjust the outlet pressure of the ammonia pressure reducer to 0.06MPa~0.12MPa, close the nitrogen bypass hand valve after ammonia is introduced, open the constant ammonia needle valve and adjust it to 5L / min~15 / min, open the control ammonia needle valve and adjust the control ammonium flowmeter to a position close to 5L / min. The first stage: after the main control instrument reaches the temperature, open the valve of the test gas inlet and the knob switch of the test gas flowmeter. And keep the test gas flowmeter value at 0.2L~0.5L / min. Adjust the opening of the constant ammonia valve to keep the U-type pressure gauge differential pressure at 200KPa~1000KPa. By adjusting the constant ammonia and controlling the flow rate of ammonia, ensure that the ammonia decomposition rate is maintained at 30%~50%. Second stage: After the control instrument reaches the temperature, adjust the opening of the constant ammonia valve to keep the U-type pressure gauge differential pressure at 200KPa~1000KPa. Adjust the knob of the test gas flowmeter to keep the test gas flow at 0.2L~0.5L / min. By adjusting the constant ammonia and controlling the flow rate of ammonia, ensure that the ammonia decomposition rate is maintained at 60%~80%. After nitriding is completed, first introduce nitrogen and maintain positive pressure in the furnace, the nitrogen flow rate is (2~3)m 3 / h (pressure display value 2-3), then close the valve of the liquid ammonia tank, and finally close the main valve on the bus. Close the valve of the test gas inlet and the inlet knob of the test gas flow meter.

[0049] When the furnace temperature drops below 150℃, turn off the nitrogen and take the parts out of the furnace. When taking the parts out of the furnace, pay attention to: insert the parts into the foam board and pack them to prevent them from being bumped, clean the parts with clean kerosene, and dry them. Then insert the parts into the foam board and pack them to prevent them from being bumped.

[0050] Through the above-mentioned process method, the surface hardness of 1Cr11Ni23Ti3MoB material shaft parts can be increased, and the wear resistance of the parts can be improved. The technical indicators of 1Cr11Ni23Ti3MoB material parts after the above-mentioned gas nitriding process method are shown in Table 1

[0051] Table 1 Technical indicators of 1Cr11Ni23Ti3MoB material after nitriding

[0052]

[0053] A second embodiment of the present invention is:

[0054] A gas nitriding method for 1Cr11Ni23Ti3MoB shaft parts is provided, comprising the following steps:

[0055] Step 1: pre-treat the 1Cr11Ni23Ti3MoB shaft parts, and clean the surface of the 1Cr11Ni23Ti3MoB shaft parts after pre-treatment; the pre-treatment includes solution treatment and aging treatment;

[0056] Solution treatment: put 1Cr11Ni23Ti3MoB shaft parts into a box-type electric furnace, heat to 1010±10℃, keep warm for 2-3h, and oil cool;

[0057] Aging treatment: put 1Cr11Ni23Ti3MoB shaft parts into a box-type electric furnace, heat it to 750-780℃, keep it warm for 16-16.5h; cool it down to 620-660℃ with the furnace, keep it warm for 10-16h, and air cool it.

[0058] This step ensures that the HRC of the core of the part is ≥32, preparing the structure for subsequent nitriding.

[0059] Since the parameters of this process step are the solution aging process parameters of 1Cr11Ni23Ti3MoB material, the heat treatment process parameters are different for different materials.

[0060] Step 2: Dry the quartz sand, mix the ammonium chloride and quartz sand in a certain proportion, put them into a catalytic box, and load them into the furnace together with the parts; the quartz sand drying temperature is 280℃~300℃, and the insulation time is 20min~30min. After drying, cool to room temperature, mix the ammonium chloride and quartz sand in a ratio of 50g:150g, put them into a catalytic box, and load them into the furnace together with the parts.

[0061] In this step, the hydrogen chloride decomposed by ammonium chloride reacts with the oxide of the passivation film, such as chromium trioxide, and the reaction formula is as follows: Cr2O3+6HCl→2CrCl3+3H2O, thereby destroying the passivation film and allowing nitriding to proceed normally. The amount of ammonium chloride used has a great influence on the surface hardness and depth of the nitriding layer. If the amount is too much, pitting will occur on the surface of the workpiece, corroding the nitriding tank and blocking the pipeline; if the amount is too little, the effect of removing the passivation film is not good, and the nitriding layer will become thinner and uneven. Therefore, the amount of ammonium chloride used should be strictly controlled in production. Using this formula can solve the above problems and ensure the quality of parts after nitriding.

[0062] Moreover, quartz sand is easy to get wet when placed in the air for a long time, so 280℃~300℃, insulation time 20min~30min, quartz sand is dried. Ammonium chloride and quartz sand are mixed in a ratio of 50g:150g=1:3 (mass ratio), which is an empirical exploration. The amount of ammonium chloride has a great influence on the surface hardness and depth of the nitriding layer. If the amount is too much, pitting will occur on the surface of the workpiece, corroding the nitriding tank and blocking the pipeline; if the amount is too little, the effect of removing the passivation film is not good, and the nitriding layer will be thinned and uneven.

[0063] Step 3: 1Cr11Ni23Ti3MoB shaft parts are loaded into the furnace;

[0064] In step 3, the 1Cr11Ni23Ti3MoB shaft parts are placed flat on the external teeth of the furnace loading tooling, where the furnace loading tooling is a plate-like structure with external teeth, such as Figure 3-6 As shown, Gaizhou makes simple nitriding tooling for parts according to the part structure to prevent parts from stacking and ensure the quality of nitriding. After the parts are put into the furnace, the furnace door is closed.

[0065] Step 4: Open the main valve, pressure reducer and needle valve on the nitrogen pipeline, introduce nitrogen into the furnace, exhaust the gas, and control the furnace pressure to be positive. The nitrogen flow rate is 2-3m 3 / h, exhaust time 50min~70min, stop introducing nitrogen after exhausting, and start heating. The purpose of this step is to ensure that there is no oxidizing atmosphere in the furnace and to ensure that the parts are not oxidized at high temperature.

[0066] Step 5: The temperature of the nitriding furnace is raised to above 400°C, and ammonia is introduced into the furnace in two ways, one of which is normal ammonia with a flow rate of 5L / min to 15 / min, and the other is controlled ammonia with a flow rate of 5L / min. By controlling the flow rate of ammonia introduced into the furnace, the ammonia decomposition rate in the first stage can be stabilized at about 40%, and the ammonia decomposition rate in the second stage can be stabilized at about 70%.

[0067] Step 6: First stage nitriding: The nitriding furnace is heated to 540℃±5℃, and the ammonia decomposition rate in the furnace is detected to be between 30% and 50%. If so, step 7 is performed, otherwise the constant ammonia flow rate in step 5 is adjusted until the ammonia decomposition rate in the furnace is between 30% and 50%;

[0068] The specific steps include:

[0069] Step 6.1 Open the valve of the nitriding furnace test gas inlet and the test gas flow meter knob switch to ensure that the test gas flow meter value is 0.2L~0.5L / min;

[0070] Step 6.2: Adjust the opening of the constant ammonia valve to ensure that the pressure difference between the furnace and the atmosphere is within the range of 200 kPa to 1000 kPa;

[0071] Step 6.3: Fine-tune the constant ammonia and control the flow rate of ammonia to ensure that the ammonia decomposition rate is maintained at 30% to 50%.

[0072] Step 7: Keep the 1Cr11Ni23Ti3MoB shaft parts at 540℃±5℃ for 30h±1h, and fine-tune the constant ammonia and control the ammonia flow rate to ensure that the ammonia decomposition rate is maintained at 40%;

[0073] Step 8: Second stage nitriding: The nitriding furnace is heated to 570℃±5℃, and the ammonia decomposition rate in the furnace is detected to be between 60% and 80%. If so, step 9 is executed, otherwise the constant ammonia flow rate in step 5 is adjusted until the ammonia decomposition rate in the furnace is between 60% and 80%.

[0074] The specific steps include:

[0075] Step 8.1 Open the valve of the nitriding furnace test gas inlet and the test gas flow meter knob switch to ensure that the test gas flow meter value is 0.2L~0.5L / min;

[0076] Step 8.2: Adjust the opening of the constant ammonia valve to ensure that the pressure difference between the furnace and the atmosphere is within the range of 200 kPa to 1000 kPa;

[0077] Step 8.3 fine-tunes the constant ammonia and controls the flow rate of ammonia to ensure that the ammonia decomposition rate is maintained at 60% to 80%.

[0078] Step 9: Keep the 1Cr11Ni23Ti3MoB shaft parts at 570℃±5℃ for 25h±1h, and fine-tune the constant ammonia and control the flow rate of ammonia to ensure that the ammonia decomposition rate is maintained at 70%, and then clean the 1Cr11Ni23Ti3MoB shaft parts with clean kerosene.

[0079] Through the two-stage nitriding process, the heating rate of the parts is uniform and controllable, and the process parameters such as nitriding temperature and ammonia decomposition rate are stable, which can ensure the nitriding quality of the parts, and the hardness, depth and brittleness of the nitriding layer meet the requirements.

[0080] The gas nitriding process of 1Cr11Ni23Ti3MoB adopts a two-stage method for nitriding. The temperature of the first stage is 540±5℃, the holding time is 30h±1h, the ammonia decomposition rate is 30%~50%, and the setting value is 40%. The temperature of the second stage is 570±5℃, the holding time is 25h±1h, the ammonia decomposition rate is 60%~80%, and the setting value is 70%. This process parameter is the optimal process parameter after multiple tests. If this process parameter is not used, the hardness, brittleness and depth of the nitriding layer of 1Cr11Ni23Ti3MoB after gas nitriding are unqualified. This process parameter is only applicable to gas nitriding of 1Cr11Ni23Ti3MoB materials. Because the materials are different, the nitriding temperature, time, and ammonia decomposition rate are also different.

[0081] Step 10: Stop introducing ammonia into the furnace and 3 ~3m 3 / h nitrogen is introduced into the furnace and the positive pressure is maintained. The temperature of 1Cr11Ni23Ti3MoB shaft parts is lowered to below 150℃. The nitrogen is stopped and the parts are taken out of the furnace. This can prevent the parts from being oxidized at high temperature and eliminate the rest of the atmosphere in the furnace to ensure safety. Clean the parts with clean kerosene and dry them. Then insert the parts into the foam board and pack them to prevent bumps, ensure the surface quality of the parts and prevent bumps.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the field can easily think of various equivalent modifications or substitutions within the technical scope disclosed by the present invention, and these modifications or substitutions should all be covered within the protection scope of the present invention.

Claims

1. 1 Cr11Ni23Ti3MoB shaft parts gas nitriding method, characterized in that: The following steps are involved: Step 1: pre-treat the 1Cr11Ni23Ti3MoB shaft parts, and clean the surface of the 1Cr11Ni23Ti3MoB shaft parts after pre-treatment; Step 2: Dry the quartz sand, mix the ammonium chloride and quartz sand in a certain proportion, put them into the catalytic box, and load them into the furnace together with the parts; Step 3: 1Cr11Ni23Ti3MoB shaft parts are loaded into the furnace; Step 4: Introduce nitrogen into the furnace and exhaust it; Step 5: The temperature of the nitriding furnace is raised to above 400°C, and ammonia is introduced into the furnace in two ways, one of which is constant ammonia with a flow rate of 5L / min to 15 / min, and the other is controlled ammonia with a flow rate of 5L / min; Step 6: The nitriding furnace is heated to 540°C ± 5°C, and the ammonia decomposition rate in the furnace is detected to be between 30% and 50%. If so, step 7 is performed, otherwise the constant ammonia flow rate in step 5 is adjusted until the ammonia decomposition rate in the furnace is between 30% and 50%. Step 7: 1Cr11Ni23Ti3MoB shaft parts are kept at 540℃±5℃ for 30h±1h; Step 8: The nitriding furnace is heated to 570°C ± 5°C, and the ammonia decomposition rate in the furnace is detected to be between 60% and 80%. If so, step 9 is performed, otherwise the constant ammonia flow rate in step 5 is adjusted until the ammonia decomposition rate in the furnace is between 60% and 80%. Step 9: 1Cr11Ni23Ti3MoB shaft parts are kept at 570℃±5℃ for 25h±1h; Step 10: Stop introducing ammonia into the furnace and 3 ~3m 3 / h nitrogen is introduced into the furnace, and the temperature of 1Cr11Ni23Ti3MoB shaft parts is cooled down to below 150℃ along the way. Then the introduction of nitrogen is stopped and the parts are taken out of the furnace.

2. The gas nitriding method for 1Cr11Ni23Ti3MoB shaft parts according to claim 1, characterized in that: In step 1, the 1Cr11Ni23Ti3MoB shaft parts are pretreated, including solution treatment and aging treatment; Solution treatment: put 1Cr11Ni23Ti3MoB shaft parts into a box-type electric furnace, heat to 1010±10℃, keep warm for 2-3h, and oil cool; Aging treatment: put 1Cr11Ni23Ti3MoB shaft parts into a box-type electric furnace, heat it to 750-780℃, keep it warm for 16-16.5h; cool it down to 620-660℃ with the furnace, keep it warm for 10-16h, and air cool it.

3. The gas nitriding method for 1Cr11Ni23Ti3MoB shaft parts according to claim 2 is characterized in that: In step 2, quartz sand is dried at a temperature of 280°C to 300°C and a holding time of 20min to 30min. After drying, the mixture is cooled to room temperature. Ammonium chloride and quartz sand are mixed in a ratio of 50g:150g, placed in a catalytic box, and loaded into the furnace together with the parts.

4. The gas nitriding method for 1Cr11Ni23Ti3MoB shaft parts according to claim 3 is characterized in that: In step 3, the 1Cr11Ni23Ti3MoB shaft parts are placed flat on the external teeth of the furnace loading tooling, wherein the furnace loading tooling is a plate-like structure with external teeth.

5. The gas nitriding method for 1Cr11Ni23Ti3MoB shaft parts according to claim 4, characterized in that: Step 4: Introduce nitrogen into the furnace and exhaust it; the nitrogen flow rate is 2-3m 3 / h, exhaust time 50min~70min, after exhausting, stop introducing nitrogen and start heating.

6. The gas nitriding method for 1Cr11Ni23Ti3MoB shaft parts according to claim 5, characterized in that: Step 6 specifically includes the following steps: Step 6.1 Open the valve of the nitriding furnace test gas inlet and the test gas flow meter knob switch to ensure that the test gas flow meter value is 0.2L~0.5L / min; Step 6.2: Adjust the opening of the constant ammonia valve to ensure that the pressure difference between the furnace and the atmosphere is within the range of 200 kPa to 1000 kPa; Step 6.3: Fine-tune the constant ammonia and control the flow rate of ammonia to ensure that the ammonia decomposition rate is maintained at 30% to 50%.

7. The gas nitriding method for 1Cr11Ni23Ti3MoB shaft parts according to claim 6, characterized in that: In step 7, the 1Cr11Ni23Ti3MoB shaft parts are kept at 540°C±5°C for 30h±1h, while fine-tuning the constant ammonia and controlling the ammonia flow rate to ensure that the ammonia decomposition rate is maintained at 40%.

8. The gas nitriding method for 1Cr11Ni23Ti3MoB shaft parts according to claim 7, characterized in that: Step 8 specifically includes the following steps: Step 8.1 Open the valve of the nitriding furnace test gas inlet and the test gas flow meter knob switch to ensure that the test gas flow meter value is 0.2L~0.5L / min; Step 8.2: Adjust the opening of the constant ammonia valve to ensure that the pressure difference between the furnace and the atmosphere is within the range of 200 kPa to 1000 kPa; Step 8.3 fine-tunes the constant ammonia and controls the flow rate of ammonia to ensure that the ammonia decomposition rate is maintained at 60% to 80%.

9. The gas nitriding method for 1Cr11Ni23Ti3MoB shaft parts according to claim 8, characterized in that: In step 9, the 1Cr11Ni23Ti3MoB shaft parts are kept at 570°C±5°C for 25h±1h, while fine-tuning the constant ammonia and controlling the ammonia flow rate to ensure that the ammonia decomposition rate is maintained at 70%.

10. The gas nitriding method for 1Cr11Ni23Ti3MoB shaft parts according to claim 9, characterized in that: The method also includes step 11, cleaning the 1Cr11Ni23Ti3MoB shaft parts with clean kerosene and drying them; and step 12, inserting the single 1Cr11Ni23Ti3MoB shaft parts into a foam board for packaging to prevent collision.

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