Method for efficiently increasing the nanocrystalline thickness of aeroengine blade bearing material

Abstract

The application relates to a method for efficiently increasing the nanocrystalline thickness of aeroengine blade bearing material, which comprises the following steps: adjusting the parameters of an ultrasonic shot blasting device; performing ultrasonic shot blasting treatment on the surface of a sample by the ultrasonic shot blasting device, and the treatment time is 8-10 mins; performing cooling treatment on the sample; adjusting the parameters of an electric shock device, setting the shock times to be 1-2 times, the electric shock time of each time to be 0.02-0.05 s, the current size to be 65-85 A, and the current density in the sample during the electric shock treatment to be 25-35 A / mm 2 ; and performing electric shock treatment on the surface of the sample by the electric shock device. The application can refine the grains of the aeroengine blade bearing material and improve the strength of the material; meanwhile, the high-efficiency treatment of grain refinement can shorten the original required time by one order of magnitude; in addition, the thickness of the grain refinement of the material can be increased, the average grain size of the material is greatly reduced on the basis of the grain size and nanocrystalline thickness of the metal after the original ultrasonic shot blasting treatment, and high-strength grain refinement is realized.

Description

Technical Field

[0001] This invention belongs to the field of material surface strengthening technology, specifically relating to a method for efficiently increasing the nanocrystalline thickness of aero-engine blade bearing materials. Background Technology

[0002] Titanium alloys possess numerous advantages, including high matrix strength, the ability to withstand high temperatures, good vibration fatigue performance, and excellent corrosion resistance, and are currently widely used in the manufacture of turbine blades for aero-engines. M50 steel, due to its high hardness and excellent wear resistance, is frequently used in bearings for various components of aero-engines. However, as the performance requirements of aero-engines become increasingly stringent, the strength requirements for their internal parts, such as turbine blades and bearings, are also rising. The strength and properties of traditional titanium alloys and M50 bearing steel are gradually becoming insufficient to meet industry demands, necessitating further strengthening based on the original metals.

[0003] Surface nanostructuring technology is a novel surface strengthening technique that is highly efficient and can significantly improve the surface strength of metals, as well as enhance various surface properties such as wear resistance, corrosion resistance, and fatigue resistance. Ultrasonic shot peening is a highly efficient surface nanostructuring technique. Because it can significantly improve the properties of metals while maintaining the surface roughness quality, and can efficiently improve the surface quality and deformation degree of difficult-to-deform metals, it has been widely researched and applied in the fields of metal surface strengthening and metal plastic forming.

[0004] Chinese patent CN 113046532A discloses a method for improving the efficiency of nano-sizing on the surface of difficult-to-deform metallic materials. The method involves first performing ultrasonic treatment, then stopping the ultrasonic treatment when the pulsed current is strong, and applying the pulsed current again. Utilizing the electroplasticity and electrohealing properties of the current, defects after shot peening are healed, improving the material's plasticity and making subsequent shot peening easier. When the effect of the pulsed current weakens, the current application is stopped, and ultrasonic treatment is performed again. The material after this pulsed current treatment is also relatively easy to shot peening. Ultrasonic treatment and pulsed current treatment can be repeated. Therefore, this patent can achieve good results even with high-strength metals. The time spent on shot peening and current application is reduced, saving energy consumption and improving energy utilization. By repeatedly performing shot peening and current treatment, the thickness of the nanolayer can be further increased, resulting in a better surface nano-sizing effect.

[0005] Chinese patent CN 113046531A discloses a method for improving the surface nano-sizing efficiency of difficult-to-deform metal materials by in-situ electrical pulse treatment. The method involves applying pulsed current treatment to both ends of the difficult-to-deform metal during ultrasonic shot peening, utilizing the electroplastic effect generated by the pulsed current treatment to improve the plasticity of the difficult-to-deform metal and simultaneously improve the efficiency of ultrasonic shot peening during the processing. This avoids the situation where the surface nano-sizing efficiency of ultrasonic shot peening is reduced due to the poor plasticity of the metal. After shot peening, electrical pulse treatment is applied again to repair cracks caused by surface nano-sizing treatment of the metal.

[0006] The aforementioned patents all employ electropulse-assisted ultrasonic peening to treat metal surfaces, improving the nano-sizing effect. However, both processes require at least two electropulse treatments, increasing the process flow and total processing time. Furthermore, the electropulse treatment during ultrasonic peening only exerts an electroplastic effect, and the pulse current's potential is not fully utilized. In the surface nano-sizing process, ultrasonic peening plays a dominant role; the increase in nanocrystal thickness and reduction in grain size after electropulse-assisted ultrasonic peening are relatively small. The thickness of nanocrystals on the surface of difficult-to-deform metals needs improvement, and the grain size needs further refinement. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a method for efficiently increasing the nanocrystalline thickness of aero-engine blade bearing materials, which addresses the shortcomings of the existing technology. This method can refine the grains of aero-engine blade bearing materials and improve their strength. At the same time, it can achieve efficient grain refinement, reducing the time required by an order of magnitude. In addition, it can increase the grain refinement thickness of the material, and significantly reduce the average grain size based on the grain size and nanocrystalline thickness of the metal after ultrasonic shot peening, thereby achieving high-strength grain refinement.

[0008] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0009] A method for efficiently increasing the nanocrystalline thickness of aero-engine blade bearing material includes the following steps:

[0010] S1. Adjust the parameters of the ultrasonic shot peening equipment to ensure that the parameters are within a suitable range;

[0011] S2. The sample surface is ultrasonically shot peened using an ultrasonic shot peening device for 8-10 minutes.

[0012] S3. After ultrasonic shot peening, the sample is cooled down.

[0013] S4. Adjust the parameters of the electric shock equipment to a suitable range. Specifically, set the number of shocks to 1-2, the shock duration to 0.02-0.05 s per shock, the current to 65-85 A, and the current density inside the sample during the shock treatment to 25-35 A / mm². 2 ;

[0014] S5. The sample surface is subjected to electrical impact treatment using an electrical impact device.

[0015] In the above scheme, in step S1, the frequency of the ultrasonic shot peening equipment is set to 15kHz-20kHz.

[0016] In the above scheme, in step S1, tungsten carbide pellets are used, and the number of pellets is 20-35.

[0017] In the above scheme, the ultrasonic shot peening equipment includes an ultrasonic generator, an ultrasonic transducer, an amplitude transformer and an ultrasonic nozzle connected in sequence. Shot particles are laid on the surface of the ultrasonic nozzle, and the sample is installed above the ultrasonic nozzle by a clamp.

[0018] In the above scheme, in step S3, the sample is placed at room temperature for 1-2 hours or cooled down to room temperature quickly using cold water.

[0019] In the above scheme, the electric shock device includes a variable power supply and a specimen clamping device. In step S5, the specimen clamping device is clamped at both ends of the longitudinal direction of the specimen, and the variable power supply is turned on to energize the specimen so that it is subjected to the effect of electric shock.

[0020] The beneficial effects of this invention are as follows:

[0021] 1. This invention proposes a highly efficient method for increasing the nanocrystalline thickness of aero-engine blade and bearing materials, ensuring it fully meets current strength requirements. It significantly increases the nanocrystalline thickness of aero-engine blade and bearing materials by generating nanocrystals and increasing the thickness of the nanocrystalline layer to enhance material strength and meet current industrial demands. This invention not only gives titanium alloys a thicker, high-performance nanocrystalline layer but also significantly reduces the average grain size, greatly improving the mechanical properties of titanium alloys. Furthermore, this invention solves the problem of low efficiency in existing surface strengthening methods, improving efficiency by nearly an order of magnitude.

[0022] 2. This invention applies ultrasonic shot peening combined with electrical impact treatment to aero-engine blades and bearing materials. The two processes are asynchronous, resulting in a shorter overall process flow. Compared to electrical pulse-assisted ultrasonic shot peening, this process is simpler, reduces processing time, and increases strengthening efficiency. Furthermore, it further refines the grains based on the original ultrasonic shot peening treatment, significantly increasing the degree of grain refinement in titanium alloys and greatly shortening the processing time. The size and thickness of the nanocrystals after nano-peening are much larger than those of the original metal material and the metal material after electrical pulse-assisted ultrasonic shot peening. Attached Figure Description

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0024] Figure 1 This is a schematic diagram of the ultrasonic shot peening equipment used in the method of this invention;

[0025] Figure 2 This is a schematic diagram of the electrical impact device in the method of the present invention;

[0026] Figure 3 This is the cross-sectional electron backscatter diffraction pattern of the titanium alloy after the first ultrasonic shot peening treatment in Embodiment 1 of the present invention;

[0027] Figure 4 This is the cross-sectional electron backscatter diffraction pattern of the titanium alloy after the second electrical shock treatment in Embodiment 1 of the present invention;

[0028] Figure 5 This is the cross-sectional electron backscatter diffraction pattern of M50 steel after the first ultrasonic shot peening treatment in Embodiment 2 of the present invention;

[0029] Figure 6 This is the cross-sectional electron backscatter diffraction pattern of M50 steel after the second electrical shock treatment in Embodiment 2 of the present invention.

[0030] In the diagram: 10. Ultrasonic shot peening equipment; 11. Ultrasonic generator; 12. Ultrasonic transducer; 13. Amplitude bar; 14. Ultrasonic nozzle; 15. Shot pellets; 16. Fixture.

[0031] 20. Electrical impact equipment; 21. Specimen clamping device; 22. Variable power supply;

[0032] 30. Sample. Detailed Implementation

[0033] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0034] The first objective of this invention is to refine the grain size of the aero-engine blade bearing material to improve its strength and meet industrial requirements. The second objective is to achieve efficient processing of the grain refinement process of the aero-engine blade bearing material, reducing the original processing time by an order of magnitude. The third objective is to increase the grain refinement thickness of the aero-engine blade bearing material, significantly reducing the average grain size based on the original grain size and nanocrystal thickness of the metal after ultrasonic shot peening, thereby achieving high-strength grain refinement.

[0035] To achieve the above objectives, the present invention provides a method for efficiently increasing the nanocrystalline thickness of aero-engine blade bearing materials, comprising the following steps:

[0036] S1. Adjust the parameters of the ultrasonic shot peening equipment 10 to ensure they are within a suitable range. For example... Figure 1 As shown, the ultrasonic shot peening equipment 10 includes an ultrasonic generator 11, an ultrasonic transducer 12, an amplitude transformer 13, and an ultrasonic nozzle 14 connected in sequence. Shot pellets 15 are laid on the surface of the ultrasonic nozzle 14, and the sample 30 is mounted above the ultrasonic nozzle 14 using a clamp 16. The frequency of the ultrasonic shot peening equipment 10 is set to 15kHz-20kHz. Tungsten carbide shot pellets 15 are used, and the number of pellets is 20-35.

[0037] S2. The surface of the sample 30 is subjected to ultrasonic shot peening treatment using an ultrasonic shot peening device 10. This involves using an ultrasonic generator 11 to generate ultrasonic energy, then using an ultrasonic transducer 12 to convert the ultrasonic energy into mechanical energy. The amplitude of the mechanical vibration is amplified by an amplitude transformer 13, and the ultrasonic nozzle 14 drives the shot particles 15 to impact the sample surface through mechanical vibration, causing severe plastic deformation of the material surface. The ultrasonic shot peening treatment time is 8-10 minutes.

[0038] The surface treated by ultrasonic shot peening is the side of the sample with the larger surface area. Appropriate parameters are adjusted to treat only one side of the sample. This process refines the grains inside the sample to a certain extent, resulting in a basic improvement in strength. At this point, the grains inside the sample exhibit a gradient nano-sized phenomenon, and the sample strength has been significantly improved; this is the first step of the strengthening process.

[0039] S3. After ultrasonic shot peening, sample 30 is cooled. Sample 30 can be placed at room temperature for 1-2 hours or cooled rapidly with cold water.

[0040] S4. Adjust the parameters of the electric shock equipment to bring them within a suitable range. For example... Figure 2As shown, the electrical shock device 20 includes a specimen clamping device 21 and a variable power supply 22. The electrical shock time is set to 0.02-0.05 s, the number of shocks is 1-2, the current is 65-85 A, and the current density inside the specimen during the electrical shock treatment is 25-35 A / mm². 2 ;

[0041] S5. The surface of the sample 30 is subjected to electrical shock treatment using an electrical shock device 20. The sample clamping device 21 clamps the sample 30 at both ends along its longitudinal direction, and the variable power supply 22 is turned on to energize the sample 30, subjecting it to the effect of electrical shock. This is the second strengthening process. Electrical shock treatment is a novel nano-sizing process that can further refine the grains of the metal through recrystallization, increasing the number of metal nanocrystals. Electrical shock treatment is shorter, an order of magnitude shorter than electrical pulse treatment, and the current generation method differs (electric pulse is a voltage source, while electrical shock is a current source), resulting in a much higher current density in electrical shock treatment. Furthermore, electrical shock can further nano-size the metal on top of ultrasonic shot peening. The role of electrical shock is to directly nano-size the metal, maximizing the degree of nano-sizing; while electrical pulse treatment softens the metal and repairs metal defects. Ultrasonic shot peening plays a dominant role in metal nano-sizing. Therefore, after this second efficient strengthening process, high-performance aero-engine blade and bearing materials with a thicker grain refinement layer and ultra-fine grain size have been prepared.

[0042] This invention employs a primary mechanical surface strengthening treatment. Ultrasonic energy is transferred to the surface of an aero-engine blade bearing material (taking titanium alloy as an example) through energy conversion and mechanical vibration. This causes severe plastic deformation on the titanium alloy surface, generating beneficial residual compressive stress. The surface grains of the titanium alloy are significantly refined, and the internal grains exhibit a gradient nanostructure. This significantly improves the surface strength and wear resistance of the titanium alloy, providing a foundation for the efficient preparation of high-performance, high-strength, and high-wear-resistant novel aero-engine blade material titanium alloys. Following a period of cooling, the titanium alloy treated with the primary mechanical surface strengthening treatment is protected from overheating that could affect its internal grain structure. This also prevents any impact on the safety, efficiency, and accuracy of the subsequent electrical shock treatment, reducing the influence of grain changes caused by thermal effects. Finally, through a second electro-impact treatment, the two ends of the titanium alloy are clamped by the electrodes of the electro-impact device 20. A large current passes through the interior of the mechanically surface-strengthened titanium alloy in a very short time, i.e., tens of milliseconds. Accompanied by electroplasticity and grain refinement, the average grain size inside the titanium alloy is significantly reduced, the thickness of the grain refinement layer is further increased, and the time required to achieve the target grain size and grain refinement layer thickness is significantly shortened. The strengthened titanium alloy obtained by this invention also has high hardness, excellent mechanical properties, and strong wear resistance, thus improving the quality of the titanium alloy.

[0043] Compared to existing electrical pulse-assisted ultrasonic shot peening, the process of this invention is simpler and takes less time, and the prepared metal material has a thicker nanocrystalline layer, smaller nanocrystal size, and better mechanical properties and strength.

[0044] The technical effects of the method of the present invention will be specifically described below through specific embodiments.

[0045] Example 1: Titanium alloy, the original material of aero-engine blades, was selected as the original sample. The sample size was 10mm-30mm thick × 30mm-60mm long × 20mm-50mm wide.

[0046] A method for efficiently increasing the nanocrystalline thickness of aero-engine blade bearing material includes the following steps:

[0047] (1) Adjust the parameters of the ultrasonic shot peening equipment 10, which are set to a frequency of 20kHz and a time of 8mins.

[0048] (2) The titanium alloy sample is subjected to ultrasonic shot peening. The ultrasonic energy is transferred to the surface of the titanium alloy by using shot 15, which causes severe plastic deformation on the surface of the titanium alloy. 20-35 shot peening particles are used.

[0049] (3) After ultrasonic shot peening, the sample is cooled down by placing it at room temperature for 1-2 hours or by using cold water to cool it down quickly.

[0050] (4) Adjust the parameters of the electric shock device 20 to set the electric shock time to 0.04s and the current to 70A.

[0051] (5) The positive and negative electrodes of the electric shock device 20 are clamped at both ends of the longitudinal direction of the sample to perform electric shock treatment on the titanium alloy sample, so that the internal grains are further refined and the thickness of the grain refinement layer is greatly increased.

[0052] like Figure 3 and Figure 4 As shown, Figure 3 The lower half, near the substrate of the sample, has coarser grains, with an overall average grain size of approximately 2-2.5 μm. Figure 4 The grains in the lower half of the sample near the base layer are significantly refined, with an overall average grain size of approximately 1-1.5 μm. The grain refinement layer of the titanium alloy nearly doubled, and the average grain size decreased by 1-3 times.

[0053] Example 2: M50 steel, the material of aircraft engine bearings after heat treatment, was selected as the original sample. The sample size was 10mm-30mm thick × 30mm-60mm long × 20mm-50mm wide.

[0054] A method for efficiently increasing the nanocrystalline thickness of aero-engine blade bearing material includes the following steps:

[0055] (1) Adjust the parameters of the ultrasonic shot peening equipment 10, which are set to a frequency of 20kHz and a time of 8mins.

[0056] (2) The M50 steel sample was subjected to ultrasonic shot peening. The ultrasonic energy was transferred to the surface of the M50 steel by using shot pellets of size 15, causing severe plastic deformation on the surface of the M50 steel. The shot pellets used were 20-35.

[0057] (3) After ultrasonic shot peening, the sample is cooled down by placing it at room temperature for 1-2 hours or by using cold water to cool it down quickly.

[0058] (4) Adjust the parameters of the electric shock device 20 to set the electric shock time to 0.04s and the current to 70A.

[0059] (5) Clamp the positive and negative electrodes of the electric shock device 20 at both ends of the longitudinal direction of the sample. Perform electric shock treatment on the M50 steel sample to induce an electroplastic effect inside the M50 steel sample, further refine the internal grains, and significantly increase the thickness of the grain refinement layer.

[0060] like Figure 5 and Figure 6 As shown in the statistics Figure 5 The grain size is approximately 0.5-1 μm. Figure 6 The grain size is approximately 0.1-0.5 μm. The grain refinement layer of M50 steel increases by 1-3 times, and the average grain size decreases by 1-3 times.

[0061] The above embodiments verify that the method of the present invention can achieve significant grain size refinement, further reducing the average grain size compared to that of samples strengthened by ultrasonic shot peening alone. Simultaneously, the present invention achieves a significant increase in the thickness of the nanocrystalline layer, with the thickness of the refined grain layer increasing by approximately 1-3 times compared to samples strengthened by ultrasonic shot peening alone. In terms of the processing, the present invention is the first to use a combined treatment of ultrasonic shot peening for mechanical surface nano-sizing and electro-impact treatment, significantly reducing the time required to obtain the target grain size and ultrafine grain layer thickness. Compared to samples strengthened by ultrasonic shot peening alone, the time required to prepare high-performance novel aero-engine blade bearing materials is shortened by nearly an order of magnitude. The present invention provides industrial convenience for manufacturing high-performance, high-strength, and high-wear-resistant novel aero-engine blade bearing materials, making the preparation process more efficient and of higher quality.

[0062] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A method for efficiently increasing the nanocrystalline thickness of a gas turbine blade bearing material, characterized by, The blade material is titanium alloy, and the bearing material is M50 steel. The method includes the following steps: S1. Adjust the parameters of the ultrasonic shot peening equipment to make them fall within a suitable range, wherein the frequency of the ultrasonic shot peening equipment is set to 15kHz-20kHz. S2. The sample surface is ultrasonically shot peened using an ultrasonic shot peening device for 8-10 minutes. S3. After ultrasonic shot peening, the sample is cooled down. S4. Adjust the parameters of the electrical impact equipment to a suitable range. The electrical impact equipment includes a variable power supply and a specimen clamping device. Set the number of impacts to 1-2, the duration of each impact to 0.02-0.05 s, the current to 65-85 A, and the current density inside the specimen during the electrical impact treatment to 25-35 A / mm². 2 ; S5. Clamp the specimen clamping device at both ends of the specimen in the longitudinal direction, turn on the variable power supply to energize the specimen, and perform electrical impact treatment on the specimen surface.

2. The method of claim 1, wherein the thickness of the nanocrystalline layer is increased by at least 50% in the high performance aeroengine blade bearing material. In step S1, tungsten carbide pellets are used, and the number of pellets is 20-35.

3. The method of claim 1, wherein the thickness of the nanocrystalline layer is increased by at least 50% in the high performance aeroengine blade bearing material. The ultrasonic shot peening equipment includes an ultrasonic generator, an ultrasonic transducer, an amplitude transformer, and an ultrasonic nozzle connected in sequence. Shot particles are laid on the surface of the ultrasonic nozzle, and the sample is mounted above the ultrasonic nozzle by a clamp.

4. The method of claim 1, wherein the thickness of the nanocrystalline layer is increased by at least 50% in the high performance aeroengine blade bearing material. In step S3, the sample is placed at room temperature for 1-2 hours or cooled down to room temperature quickly using cold water.

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