New-generation high-temperature alloy GH4065A tool surface pretreatment method

Abstract

The invention relates to the technical field of machining tools, and discloses a new-generation high-temperature alloy GH4065A tool surface pretreatment method, flicker temperature field treatment is carried out on the surface of a GH4065A tool, a high-speed changing temperature field enables crystal lattices on the surface of the tool to expand and contract in a reciprocating mode, dislocation increment is induced, defects such as vacancies and gaps are formed, alternating stress is generated, surface residual stress is eliminated, and the surface of the GH4065A tool is obtained. And the surface is in a micro-stress or stress disappearance state. During nitrogen impact nitriding treatment, due to dislocation increment, vacancies and gaps caused by a high-frequency change temperature field, diffusion resistance of nitrogen atoms in a matrix is reduced, and permeation of the nitrogen atoms from the surface to the interior is accelerated. According to the method, the surface stress state of the base body can be greatly changed while the overall performance of the tool base body is not changed, and the surface nitrogen-rich layer is obtained. The low-stress nitrogen-rich surface can improve the growth behavior of the deposited TiAlN coating, improve the performance of the coating and reduce the friction coefficient and the abrasion loss of the tool.

Description

Technical Field

[0001] The invention relates to the technical field of machining tools and discloses a surface pretreatment method for a new generation of high-temperature alloy GH4065A tools. Background Art

[0002] GH4065A is a wear-resistant material with excellent red hardness, manufactured using powder metallurgy methods. It utilizes TiCN as the hard phase, Ni / Co as the binder, and elements such as Mo2C and WC for microstructure control. It is currently increasingly used in the aviation high-temperature alloy machining tool industry, suitable for semi-finishing and finishing operations, and is an ideal alternative to cemented carbide tools. The emergence of new materials such as the new generation of high-temperature alloy GH4065A has significantly improved properties such as strength and hardness, placing even stricter demands on tool materials. Therefore, to meet the current development requirements of the machining industry, over 90% of cutting tools are coated to improve machining performance and tool life.

[0003] However, due to the high residual stress on the surface of cermet tools before coating and the low chemical affinity of the coating ions, the coating often has a weak bond with the cermet growth. When machining difficult-to-machine materials such as the high-temperature alloy GH4065A, the tool coating is prone to peeling, resulting in shortened tool life and poor machining quality of the high-temperature alloy GH4065A workpiece. Summary of the Invention

[0004] The purpose of the present invention is to provide a new generation of high-temperature alloy GH4065A tool surface pretreatment method, which can significantly change the surface stress state of the substrate without changing the overall performance of the GH4065A tool substrate, improve the growth behavior of the deposited TiAlN coating, effectively improve the performance of the surface TiAlN coating, and significantly reduce the friction coefficient and wear of the GH4065A tool.

[0005] In order to achieve the above technical effects, the technical solution adopted by the present invention is: The new generation of high-temperature alloy GH4065A tool surface pretreatment methods include: The surface of the GH4065A tool is subjected to a flash temperature field treatment method, wherein the flash temperature field treatment method comprises: raising the surface temperature of the GH4065A tool to a first temperature control value within a first preset time and lowering it to a second temperature control value within a second preset time; performing 60 to 100 temperature field heating and cooling cycles within a preset total time; wherein the first temperature control value is greater than or equal to 800° C., and the first temperature control value is greater than the second temperature control value; The GH4065A tool treated with the flash temperature field is heated in a vacuum furnace to a third temperature control value, and a surface of the GH4065A tool treated with the flash temperature field is subjected to an airflow impact nitriding treatment using high-purity nitrogen gas with a purity greater than 99.9% under a preset atmosphere pressure. After the nitriding treatment lasts for a preset treatment time, the GH4065A tool is cooled to room temperature in the furnace and then taken out of the furnace; A TiAlN coating is deposited on the surface of the GH4065A tool after nitriding by a PVD deposition method, thereby completing the pretreatment of the wear resistance of the surface of the GH4065A tool.

[0006] Furthermore, the first preset time ranges from 4s to 10s, the second preset time ranges from 2s to 5s, the first temperature control value ranges from 700 to 1000°C, the second temperature control value ranges from 200 to 500°C, and the total preset time is greater than 8 minutes.

[0007] Furthermore, the third temperature control value ranges from 700 to 1000°C.

[0008] Furthermore, the method for performing a flash temperature field treatment on the surface of the GH4065A tool includes placing the GH4065A tool in an alternating magnetic field, and achieving temperature rise and fall cycle control of the surface temperature field of the GH4065A tool by adjusting the direction and magnitude of the magnetic field.

[0009] Furthermore, the nitriding treatment time is greater than 20 minutes. During the nitriding treatment, the nitrogen inlet flow rate is 80-120 sccm, the outlet flow rate is 70-110 sccm, and the difference between the inlet flow rate and the outlet flow rate is greater than or equal to 8 sccm.

[0010] Furthermore, the method of depositing a TiAlN coating on the surface of the GH4065A tool after nitriding by using a PVD deposition method includes: selecting a target material as Ti 33 Al 67 Alloy target and Ti target; nitrogen and argon are passed during the deposition process, the chamber pressure is set to 4.2Pa, the argon flow rate is fixed at 150sccm, and the rest is high-purity nitrogen; target current is 200A, frequency is 30kHz, duty cycle is 75%, substrate bias is -80V, deposition temperature is 550 degrees Celsius, and the total deposition time is 2 hours before cooling to room temperature with the furnace.

[0011] Furthermore, the target material used in the deposition process is 4 groups of Ti with a purity higher than 99%. 33 Al 67 alloy targets and 2 sets of high-purity Ti targets with a purity higher than 99%.

[0012] Furthermore, before the flash temperature field treatment was performed on the surface of the GH4065A tool, it was pre-polished with 0.5 μm diamond paste for more than 10 min.

[0013] Furthermore, before depositing the TiAlN coating on the surface of the GH4065A tool after the nitriding treatment by using the PVD deposition method, the surface of the GH4065A tool after the nitriding treatment is cleaned in advance by using ultrasonic alcohol.

[0014] Compared with the existing technology, the beneficial effects of the present invention are: the present invention can significantly change the surface stress state of the substrate and obtain a surface nitrogen-rich layer without changing the overall performance of the GH4065A tool substrate; the low-stress nitrogen-rich surface state can further improve the growth behavior of the deposited TiAlN coating, effectively improve the performance of the surface TiAlN coating, and significantly reduce the friction coefficient and wear of the GH4065A tool. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is the SEM image of the membrane-substrate interface and coating morphology of the control sample; Figure 2 The SEM images of the film-substrate interface and coating morphology of the sample obtained in Example 2; Figure 3 The SEM images of the sample membrane-substrate interface and coating morphology obtained in Example 3; Figure 4 Curves showing the change of friction coefficient over time for GH4065A samples obtained with different pretreatment methods. DETAILED DESCRIPTION

[0016] The present invention will be described in further detail below with reference to the embodiments and accompanying drawings. However, this should not be construed as limiting the scope of the present invention to the following embodiments, as all technologies implemented based on the present invention fall within the scope of the present invention.

[0017] Example 1 The new generation of high-temperature alloy GH4065A tool surface pretreatment methods include: The surface of the GH4065A tool is subjected to a flash temperature field treatment method, wherein the flash temperature field treatment method comprises: raising the surface temperature of the GH4065A tool to a first temperature control value within a first preset time and lowering it to a second temperature control value within a second preset time; performing 60 to 100 temperature field heating and cooling cycles within a preset total time; wherein the first temperature control value is greater than or equal to 800° C., and the first temperature control value is greater than the second temperature control value; The GH4065A tool treated with the flash temperature field is heated in a vacuum furnace to a third temperature control value, and a surface of the GH4065A tool treated with the flash temperature field is subjected to an airflow impact nitriding treatment using high-purity nitrogen gas with a purity greater than 99.9% under a preset atmosphere pressure. After the nitriding treatment lasts for a preset treatment time, the GH4065A tool is cooled to room temperature in the furnace and then taken out of the furnace; A TiAlN coating is deposited on the surface of the GH4065A tool after nitriding by a PVD deposition method, thereby completing the pretreatment of the wear resistance of the surface of the GH4065A tool.

[0018] In this embodiment, by subjecting the surface of a GH4065A tool to a flash temperature field treatment, the high-speed temperature field causes the surface lattice of the GH4065A tool to reciprocating expansion and contraction, inducing surface dislocation growth, forming more defects such as vacancies and gaps, and simultaneously generating alternating stresses that conflict with and eliminate the surface residual stress, causing the surface to exhibit microstress or even stress disappearance. In addition, during the impact nitriding treatment using nitrogen, the dislocation growth caused by the high-frequency temperature field and the vacancies and gaps formed reduce the diffusion resistance of nitrogen atoms in the matrix, accelerating the penetration of nitrogen atoms from the surface to the interior. The present invention can significantly change the surface stress state of the substrate without changing the overall performance of the GH4065A tool substrate, and obtain a surface nitrogen-rich layer. The low-stress nitrogen-rich surface state can further improve the growth behavior of the deposited TiAlN coating, effectively improving the performance of the surface TiAlN coating, and significantly reducing the friction coefficient and wear of the GH4065A tool.

[0019] Example 2 1) Sample preparation: GH4065A samples were flattened using a diamond grinding wheel, and the flattened surface was polished to a mirror finish using 0.5 μm diamond grinding paste; 2) Sample cleaning: After polishing, the sample is ultrasonically cleaned in an alcohol solution; 3) The GH4065A sample was treated with a high-frequency changing magnetic field to complete the alternating eddy current change, realizing a short-term rapid temperature rise and fall in the tool surface temperature field. The temperature was raised to 800°C in 4 seconds and dropped to 300°C in 2 seconds. 100 high-speed temperature field rise and fall cycles were achieved within 10 minutes, and then the tool was cooled to room temperature.

[0020] 4) Coupled with high-energy nitrogen atom treatment, the samples were placed on the boat at equal distances in the XY direction, and the furnace was vacuum treated until the vacuum degree was less than 1×10 -2 Pa; 5) High-purity nitrogen gas with a purity of >99.9% was then introduced to a certain pressure. The sample was then heated to 800°C at a heating rate of 10°C / min. The furnace inlet was positioned directly above the sample, and the furnace outlet was positioned directly below the sample. The inlet and outlet of the furnace created a disturbance in the gas flow, causing it to flow across the sample surface in a directional manner. During this treatment, the nitrogen inlet flow rate was 100 sccm, the outlet flow rate was 90 sccm, and the treatment time was 30 minutes. 6) Cooling, cooling to room temperature and then taking out of the furnace; 7) Cleaning before coating: Place the sample after nitriding treatment in an ultrasonic cleaning line for cleaning and drying; 8) PVD coating, prepare TiAlN coating according to the predetermined process: the target material is 4 groups of Ti with a purity higher than 99% 33 Al 67 The TiAlN functional layer was deposited using an alloy target and two sets of high-purity Ti targets at a target current of 200 A, a frequency of 30 kHz, a duty cycle of 75%, and a substrate bias of -80 V. High-purity nitrogen and argon were used during the deposition process. The chamber pressure was set to 4.2 Pa, the argon flow rate was fixed at 150 sccm, and the remainder was high-purity nitrogen. The deposition temperature was 550 degrees Celsius, and the total deposition time was 2 hours. 9) Take out of the furnace after cooling to room temperature.

[0021] Example 3: 1) Sample preparation: GH4065A samples were flattened using a diamond grinding wheel, and the flattened surface was polished to a mirror finish using 0.5 μm diamond grinding paste; 2) Sample cleaning: After polishing, the sample is ultrasonically cleaned; 3) The GH4065A sample was treated with a high-frequency changing magnetic field to complete the alternating eddy current change, realizing a short-term rapid temperature rise and fall in the tool surface temperature field. The temperature was raised to 800°C in 10 seconds and dropped to 300°C in 5 seconds. 40 high-speed temperature field rise and fall cycles were achieved within 10 minutes, and then the tool was cooled to room temperature.

[0022] 4) Coupled with high-energy nitrogen atom treatment, the samples were placed on the boat at equal distances in the XY direction, and the furnace was vacuum treated until the vacuum degree was less than 1×10 -2 Pa; 5) High-purity nitrogen gas with a purity of >99.9% was then introduced to a certain pressure. The sample was then heated to 800°C at a heating rate of 10°C / min. The furnace inlet was positioned directly above the sample, and the furnace outlet was positioned directly below the sample. The inlet and outlet of the furnace created a disturbance in the gas flow, causing it to flow across the sample surface in a directional manner. During this treatment, the nitrogen inlet flow rate was 100 sccm, the outlet flow rate was 90 sccm, and the treatment time was 30 minutes. 6) Cooling, cooling to room temperature and then taking out of the furnace; 7) Cleaning before coating: Place the sample after nitriding treatment in a nine-slot ultrasonic cleaning line for cleaning and drying; 8) PVD coating, prepare TiAlN coating according to the predetermined process: the target material is 4 groups of Ti with a purity higher than 99% 33 Al 67 The TiAlN functional layer was deposited using an alloy target and two sets of high-purity Ti targets at a target current of 200 A, a frequency of 30 kHz, a duty cycle of 75%, and a substrate bias of -80 V. High-purity nitrogen and argon were used during the deposition process. The chamber pressure was set to 4.2 Pa, the argon flow rate was fixed at 150 sccm, and the remainder was high-purity nitrogen. The deposition temperature was 550 degrees Celsius, and the total deposition time was 2 hours. Take out of the furnace after cooling to room temperature.

[0023] Control Example 1) Sample preparation: GH4065A samples were flattened using a diamond grinding wheel, and the flattened surface was polished to a mirror finish using 0.5 μm diamond grinding paste; 2) Sample cleaning: After polishing, the sample is ultrasonically cleaned in a nine-slot ultrasonic cleaning line; 3) PVD coating, prepare TiAlN coating according to the predetermined process: the target material is 4 groups of Ti with a purity higher than 99% 33 Al 67 The TiAlN functional layer was deposited using an alloy target and two sets of high-purity Ti targets at a target current of 200 A, a frequency of 30 kHz, a duty cycle of 75%, and a substrate bias of -80 V. High-purity nitrogen and argon were used during the deposition process. The chamber pressure was set to 4.2 Pa, the argon flow rate was fixed at 150 sccm, and the remainder was high-purity nitrogen. The deposition temperature was 550 degrees Celsius, and the total deposition time was 2 hours. 4) Take out of the furnace after cooling to room temperature.

[0024] Testing and analysis: 1. Surface stress test: Six measuring points were taken on the surface of the GH4065A samples after treatment in Example 2, Example 3, and the control example, and the surface stress of the GH4065A samples obtained by the corresponding pretreatment methods was tested. The relevant test results are shown in Table 1 below: Table 1 Statistics of surface stress distribution of GH4065A after different pretreatments (unit: MPa)

[0025] As can be seen from Table 1 above, after the surface of the GH4065A sample is pretreated by the pretreatment method of the present invention, the surface stress is significantly lower than that of the sample not treated by the method of the present invention, and the faster the heating and cooling speed and the more treatment times, the better the surface stress removal effect.

[0026] 2. Morphology Analysis: The fracture end faces of the GH4065A samples after treatment in Example 2, Example 3 and the control example were scanned by electron microscope to obtain the film-substrate interface and coating morphology of the corresponding samples; Figure 1 The SEM images of the membrane-substrate interface and coating morphology of the control sample are shown in Figure 2. Figure 2 The SEM images of the sample membrane-substrate interface and coating morphology obtained in Example 2 are as follows: Figure 3 The following is an SEM image of the membrane-substrate interface and coating morphology of the sample obtained in Example 3. It can be seen that the interface of the control example has obvious pores, and the loose interface is not conducive to the bonding strength between the coating and the substrate. In Example 2, the membrane-substrate interface is complete and tight, without obvious pores, indicating that the TiAlN coating grows well on the surface of the substrate in Example 2. In Example 3, some pores can be seen at the membrane-substrate interface, and the degree of tightness is between that of Examples 1 and 2.

[0027] 3. Friction and wear test: Figure 4 The results of the time-varying friction coefficients of the GH4065A samples after treatment with Example 2, Example 3, and the control example are shown. The results show that the friction coefficient of the control example is the highest, followed by the sample of Example 3, and the friction coefficient of Example 2 is the lowest. It should be noted that Figure 4 The friction coefficient decreased significantly between 11 minutes and 15 minutes. This is because the surface coating was broken and the substrate was gradually exposed during the friction and wear test. The 3D wear profile of each sample after the friction and wear test was analyzed. The results showed that the control sample had the deepest wear depth ( =2.6952 μm), followed by Example 3 ( =2.3595μm), the shallowest wear scar is in Example 2 ( =2.1689μm).

[0028] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A new generation of high temperature alloy GH4065A tool surface pretreatment method, characterized in that: include: The surface of the GH4065A tool is subjected to a flash temperature field treatment method, wherein the flash temperature field treatment method comprises: raising the surface temperature of the GH4065A tool to a first temperature control value within a first preset time and lowering it to a second temperature control value within a second preset time; performing 60 to 100 temperature field heating and cooling cycles within a preset total time; wherein the first temperature control value is greater than or equal to 800° C., and the first temperature control value is greater than the second temperature control value; The GH4065A tool treated with the flash temperature field is heated in a vacuum furnace to a third temperature control value, and a surface of the GH4065A tool treated with the flash temperature field is subjected to an airflow impact nitriding treatment using high-purity nitrogen gas with a purity greater than 99.9% under a preset atmosphere pressure. After the nitriding treatment lasts for a preset treatment time, the GH4065A tool is cooled to room temperature in the furnace and then taken out of the furnace; A TiAlN coating is deposited on the surface of the GH4065A tool after nitriding by a PVD deposition method, thereby completing the pretreatment of the wear resistance of the surface of the GH4065A tool.

2. The surface pretreatment method for cutting tools of the new generation high-temperature alloy GH4065A according to claim 1 is characterized in that: The first preset time ranges from 4s to 10s, the second preset time ranges from 2s to 5s, the first temperature control value ranges from 700 to 1000°C, the second temperature control value ranges from 200 to 500°C, and the total preset time is greater than 8 minutes.

3. The surface pretreatment method for cutting tools of the new generation high-temperature alloy GH4065A according to claim 1 is characterized in that: The third temperature control value ranges from 700 to 1000°C.

4. The surface pretreatment method for cutting tools of the new generation high-temperature alloy GH4065A according to claim 1 is characterized in that: The method for performing a flash temperature field treatment on the surface of a GH4065A tool comprises placing the GH4065A tool in an alternating magnetic field, and achieving a temperature rise and fall cycle control of the surface temperature field of the GH4065A tool by adjusting the direction and magnitude of the magnetic field.

5. The surface pretreatment method for cutting tools of the new generation high temperature alloy GH4065A according to claim 1 is characterized in that: The nitriding treatment time is greater than 20 minutes. During the nitriding treatment, the nitrogen inlet flow rate is 80-120 sccm, the outlet flow rate is 70-110 sccm, and the difference between the inlet flow rate and the outlet flow rate is greater than or equal to 8 sccm.

6. The surface pretreatment method for cutting tools of the new generation high temperature alloy GH4065A according to claim 1 is characterized in that: The method for depositing a TiAlN coating on the surface of the GH4065A tool after nitriding by using a PVD deposition method includes: selecting a target material as Ti 33 Al 67 Alloy target and Ti target; nitrogen and argon are passed during the deposition process, the chamber pressure is set to 4.2Pa, the argon flow rate is fixed at 150sccm, and the rest is high-purity nitrogen; target current is 200A, frequency is 30kHz, duty cycle is 75%, substrate bias is -80V, deposition temperature is 550 degrees Celsius, and the total deposition time is 2 hours before cooling to room temperature with the furnace.

7. The surface pretreatment method for cutting tools of the new generation high temperature alloy GH4065A according to claim 6, characterized in that: The target material used in the deposition process is 4 groups of Ti with a purity higher than 99%. 33 Al 67 alloy targets and 2 sets of high-purity Ti targets with a purity higher than 99%.

8. The surface pretreatment method for cutting tools of the new generation high temperature alloy GH4065A according to claim 1 is characterized in that: Before the flash temperature field treatment was performed on the surface of the GH4065A tool, it was polished with 0.5 μm diamond paste for more than 10 minutes.

9. The surface pretreatment method for cutting tools of the new generation high temperature alloy GH4065A according to claim 1, characterized in that: Before depositing the TiAlN coating on the surface of the GH4065A tool after the nitriding treatment by using the PVD deposition method, the surface of the GH4065A tool after the nitriding treatment is cleaned in advance by using ultrasonic alcohol.

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