Aviation titanium alloy laser shock strengthening and mechanical shot peening composite process strengthening method

Abstract

The invention relates to an aviation titanium alloy laser shock peening and mechanical shot peening composite process strengthening method. The method comprises the following steps: cutting an aviation titanium alloy material into a plurality of square blocks and tensile fatigue parts by using a wire cutting machine; grinding with abrasive paper, and then polishing with a polishing agent, so that the surface of the aviation titanium alloy test material is smooth; carrying out laser shock peening treatment on one part of the aviation titanium alloy test material subjected to surface treatment; performing various detections on the aviation titanium alloy test material subjected to the same parameter and different impact strengthening times; the method comprises the following steps: carrying out mechanical shot blasting on an aviation titanium alloy sample with the best detection effect, carrying out mechanical shot blasting on part of original samples, then carrying out laser shock peening, and comparing the mechanical properties of the materials subjected to shock peening in different modes to obtain an optimal result. According to the method, two processes of mechanical shot peening and laser shock peening are combined, so that the fatigue resistance, the damage resistance and the stress corrosion resistance of the material are improved.

Description

Technical Field

[0001] The invention relates to the technical field of aviation titanium alloy processing, and in particular to a composite process strengthening method of aviation titanium alloy by laser shock strengthening and mechanical shot peening. Background Art

[0002] Since ancient times, blacksmiths have realized that hammering in a cold state can make metal harder. In the Middle Ages, the sandblasting technology mastered could increase the service life of metal products. Shot peening technology has made great progress with the development of the times. With the vigorous development of laser technology, laser shock peening has been used more and more, and gradually occupied a major position. However, laser shock peening is expensive, resulting in high processing costs. For large quantities of workpieces, it is obvious that mechanical shot peening, which has more mature technology and relatively low prices, is still used. However, the precision of mechanical shot peening is poor, and it is difficult to process high-precision workpieces. Therefore, it needs to be improved. Summary of the invention

[0003] Based on this, it is necessary to provide a composite process strengthening method of aviation titanium alloy laser shock strengthening and mechanical shot peening, in order to address the problem that the traditional laser shock peening method is expensive, resulting in high processing costs, and large quantities of workpieces are obviously still better processed by mechanical shot peening, which has a more mature technology and relatively cheap price. However, the precision of mechanical shot peening is poor, and it is difficult to process high-precision workpieces.

[0004] The present invention provides a composite process strengthening method of aviation titanium alloy laser shock strengthening and mechanical shot peening, comprising:

[0005] Cutting aviation titanium alloy materials into several blocks and tensile fatigue parts by wire cutting machine;

[0006] Grind with sandpaper and then polish with polishing agent to make the surface of aviation titanium alloy test material smooth;

[0007] A portion of the surface treated aviation titanium alloy test material was subjected to laser shock strengthening treatment;

[0008] Conduct various tests on aviation titanium alloy test materials that have completed the same parameters but different impact strengthening times;

[0009] The aviation titanium alloy specimens with the best test results were subjected to mechanical shot peening, and some of the original specimens were first subjected to mechanical shot peening and then to laser shock strengthening. The mechanical properties of the materials after impact strengthening by the above different methods were compared to obtain the best results.

[0010] In one embodiment, the size of the block is 15*15 mm, and the cutting thickness of the aviation titanium alloy test material is 4 mm.

[0011] In one of the embodiments, the cross section of the tensile fatigue part is rectangular, and grooves are provided on the upper surface and the bottom of the cross section in the length direction of the tensile fatigue part, and adjacent grooves are mirror-symmetrical.

[0012] In one embodiment, the sandpaper is polished with 180 mesh, 320 mesh, 600 mesh, 800 mesh, 1000 mesh, 1500 mesh and 2500 mesh respectively.

[0013] In one embodiment, the polishing agent is a diamond suspension.

[0014] In one of the embodiments, the laser shock peening treatment conditions are: the film is black tape, the medium is water, the energy is 1J, the overlap rate is 50%, the spot diameter is 2mm, and the frequency is 5Hz.

[0015] In one embodiment, the impact strengthening times are one, two, three, or four times respectively.

[0016] In one embodiment, the detection includes tensile, fatigue, hardness and other tests, and TEM, SEM and EBSD analysis are performed on the microstructure after the detection.

[0017] The above-mentioned composite process strengthening method of aviation titanium alloy laser shock strengthening and mechanical shot peening utilizes low-cost and mature process mechanical shot peening that can be mass-produced, combined with high-precision, pollution-free laser shock strengthening, so that the aviation titanium alloy material can improve the residual compressive stress generated in the blade material after the composite processing of the two processes. Laser shock strengthening can locally utilize pulsed laser to induce ultra-high intensity shock waves to act on the surface, causing microstructural changes on the surface to improve the material's fatigue resistance, wear resistance and stress corrosion resistance. Mechanical shot peening can also be used to remove oxide scale, rust, old coatings and other surface defects on the material surface, preparing a good substrate for subsequent painting or other surface treatments. It can be widely used in aerospace, automobile manufacturing, shipbuilding and other fields, and is one of the important means to improve the reliability and performance of mechanical components. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 A schematic diagram of a process for strengthening aerospace titanium alloy by laser shock strengthening and mechanical shot peening in one embodiment;

[0020] Figure 2 It is a schematic diagram of the structure of a block specimen and a tensile fatigue piece in one embodiment. DETAILED DESCRIPTION

[0021] 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 creative work are within the scope of protection of the present invention.

[0022] It should be noted that when a component is referred to as being "fixed to" or "disposed on" another component, it may be directly on the other component or there may be a central component. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may be a central component at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in the specification of the present invention are for illustrative purposes only and do not represent the only implementation method.

[0023] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0024] In the present invention, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first feature is directly in contact with the second feature, or the first feature and the second feature are indirectly in contact through an intermediate medium. Moreover, a first feature being “above”, “above” or “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below”, “below” or “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0025] Unless otherwise defined, all technical and scientific terms used in the specification of the present invention have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used in the specification of the present invention includes any and all combinations of one or more related listed items.

[0026] Combine the following Figure 1-Figure 2 The invention discloses a composite process strengthening method of aviation titanium alloy by laser shock strengthening and mechanical shot peening.

[0027] like Figure 1 As shown, in one embodiment, a composite process strengthening method of laser shock strengthening and mechanical shot peening for aviation titanium alloy comprises:

[0028] Step S110, cutting the aviation titanium alloy material into a plurality of blocks and tensile fatigue parts by using a wire cutting machine.

[0029] Step S120, grinding with sandpaper, and then polishing with a polishing agent to make the surface of the aviation titanium alloy test material smooth.

[0030] Step S130, subjecting a portion of the surface-treated aviation titanium alloy test material to laser shock peening.

[0031] Step S140, performing various tests on the aviation titanium alloy test materials that have completed the same parameters but different impact strengthening times.

[0032] Step S150, mechanical shot peening is performed on the aviation titanium alloy sample with the best detection effect, and then some original samples are first mechanically shot peened and then laser shock strengthened, and the mechanical properties of the materials after shock strengthening in the above several different ways are compared to obtain the best result.

[0033] This composite process strengthening method of aviation titanium alloy laser shock strengthening and mechanical shot peening utilizes low-cost and mature process mechanical shot peening that can be mass-produced, combined with high-precision, pollution-free laser shock strengthening. This allows the aviation titanium alloy material to increase the residual compressive stress generated in the blade material after the composite processing of the two processes. Laser shock strengthening can locally utilize pulsed lasers to induce ultra-high-intensity shock waves to act on the surface, causing microstructural changes on the surface to improve the material's fatigue resistance, wear resistance, and stress corrosion resistance. Mechanical shot peening can also be used to remove oxide scale, rust, old coatings, and other surface defects on the material surface, preparing a good substrate for subsequent painting or other surface treatments.

[0034] In this embodiment, the size of the block is 15*15 mm, and the cutting thickness of the aviation titanium alloy test material is 4 mm.

[0035] In this embodiment, see Figure 2 The cross section of the tensile fatigue part is a rectangle, and grooves are provided on the upper surface and the bottom of the cross section in the length direction of the tensile fatigue part, and adjacent grooves are mirror-symmetrical.

[0036] In this embodiment, sandpapers of 180 mesh, 320 mesh, 600 mesh, 800 mesh, 1000 mesh, 1500 mesh and 2500 mesh are used for grinding.

[0037] In this embodiment, the polishing agent is a diamond suspension.

[0038] In this embodiment, the laser shock peening treatment conditions are: the film is a black tape, the medium is water, the energy is 1 J, the overlap rate is 50%, the spot diameter is 2 mm, and the frequency is 5 Hz.

[0039] In this embodiment, the impact strengthening times are one, two, three, and four times respectively.

[0040] In this embodiment, the detection includes tensile, fatigue, hardness and other tests, and TEM, SEM and EBSD analyses are performed on the microstructure after the detection.

[0041] Among them, TEM (Transmission Electron Microscope) refers to an analytical technique that uses various information generated when a high-energy electron beam passes through a sample in a transmission electron microscope to study the microscopic structure of the sample material. TEM uses information such as transmitted electrons, diffracted electrons, and secondary electrons generated when a high-energy electron beam passes through a sample to obtain the sample's microscopic structure, composition, and physical state.

[0042] SEM (Scanning Electron Microscope) is a large precision instrument used for high-resolution micro-area morphology analysis. It uses a finely focused electron beam to bombard the sample surface, and observes and analyzes the sample surface or fracture morphology through secondary electrons and backscattered electrons generated by the interaction between electrons and samples. The new SEM has a resolution of 1 nanometer, a magnification of 300,000 times or more, and is continuously adjustable. It also has a large depth of field, a wide field of view, and a good three-dimensional imaging effect. In addition, the combination of SEM and other analytical instruments can perform micro-area composition analysis of materials while observing microscopic morphology.

[0043] EBSD (Electron Backscatter Diffraction) is an analytical method that combines crystal micro-area orientation and crystal structure organization, and has been widely used in the characterization of material microstructure and microtexture. It provides important information such as sample crystal structure, grain orientation and crystal defects by analyzing the diffraction pattern of backscattered electrons generated after the incident electron beam interacts with the sample. EBSD can be combined with other functions of SEM to perform in-situ imaging, composition analysis, large sample analysis, rough surface imaging, etc., overcoming some defects in traditional analysis methods.

[0044] The specific application scenarios are as follows:

[0045] The aviation titanium alloy test material was cut into several 15*15mm small cubes and tensile fatigue parts by a wire cutting machine, and polished with 180 mesh, 320 mesh, 600 mesh, 800 mesh, 1000 mesh, 1500 mesh, and 2500 mesh sandpaper respectively, and then polished with diamond polishing agent to make the surface of the test material smooth.

[0046] A portion of the surface treated test materials was subjected to laser shock peening treatment. The treatment conditions were: the absorption layer was black tape, the constraint layer was water film, the laser pulse energy was 1J, the spot overlap rate was 50%, the laser spot diameter was 2mm, and the laser pulse frequency was 5Hz.

[0047] The laser shock peening treatment times were one, two, three and four times respectively. The test materials that completed the same parameters but different shock peening times were subjected to tensile, fatigue, hardness and other tests, and their microstructures were analyzed by TEM, SEM and EBSD. It was found that among the different times of laser shock peening, the specimens obtained after four times of laser shock peening had the best mechanical properties in all aspects, especially in fatigue, which was nearly doubled compared with the original specimens.

[0048] The samples after four laser shock peening treatments were then mechanically shot peened, and then the material properties of the samples first subjected to four laser shock peening treatments and then shot peening treatment were compared with those subjected to mechanical shot peening and then four laser shock peening treatments.

[0049] By combining the mature and relatively low-priced mechanical shot peening with the high-precision and high-strength laser shock strengthening process, it is an effective and feasible surface modification technology that causes plastic deformation on the surface and forms a residual compressive stress layer to improve the mechanical properties of aviation titanium alloy materials. This process can not only improve the hardness and wear resistance of the material surface, but also significantly enhance its fatigue resistance and extend the service life of aviation titanium alloy material parts. In addition, the mechanical shot peening process can also remove oxides, rust and old coatings on the surface, providing a clean and uniform base surface for subsequent coating or heat treatment processes. It is widely used in aerospace, automobile manufacturing, shipbuilding and other fields, and is one of the important means to improve the reliability and performance of mechanical parts.

[0050] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0051] The above-described embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the attached claims.

Claims

1. A composite process strengthening method of laser shock strengthening and mechanical shot peening for aviation titanium alloy, characterized in that: The method includes: Cutting aviation titanium alloy materials into several blocks and tensile fatigue parts by wire cutting machine; Grind with sandpaper and then polish with polishing agent to make the surface of aviation titanium alloy test material smooth; A portion of the surface treated aviation titanium alloy test material was subjected to laser shock strengthening treatment; Conduct various tests on aviation titanium alloy test materials that have completed the same parameters but different impact strengthening times; The aviation titanium alloy specimens with the best test results were subjected to mechanical shot peening, and some of the original specimens were first subjected to mechanical shot peening and then to laser shock strengthening. The mechanical properties of the materials after impact strengthening by the above different methods were compared to obtain the best results.

2. The method for strengthening aviation titanium alloy by laser shock strengthening and mechanical shot peening composite process according to claim 1, characterized in that: The size of the block is 15*15 mm, and the cutting thickness of the aviation titanium alloy test material is 4 mm.

3. The composite process strengthening method of aviation titanium alloy laser shock strengthening and mechanical shot peening according to claim 2 is characterized in that: The cross section of the tensile fatigue part is rectangular, and grooves are provided on the upper surface and the bottom in the length direction of the cross section of the tensile fatigue part, and adjacent grooves are mirror-symmetrical.

4. The method for strengthening aviation titanium alloy by laser shock strengthening and mechanical shot peening composite process according to claim 1, characterized in that: The sandpapers are respectively 180 mesh, 320 mesh, 600 mesh, 800 mesh, 1000 mesh, 1500 mesh and 2500 mesh for grinding.

5. The method for strengthening aviation titanium alloy by laser shock strengthening and mechanical shot peening composite process according to claim 4, characterized in that: The polishing agent is a diamond suspension.

6. The method for strengthening aviation titanium alloy by laser shock strengthening and mechanical shot peening composite process according to claim 5, characterized in that: The laser shock peening treatment conditions are: the film is a black tape, the medium is water, the energy is 1 J, the overlap rate is 50%, the spot diameter is 2 mm, and the frequency is 5 Hz.

7. The method for strengthening aviation titanium alloy by laser shock strengthening and mechanical shot peening composite process according to any one of claims 1 to 6, characterized in that: The impact strengthening times are one, two, three and four times respectively.

8. The method for strengthening aviation titanium alloy by laser shock strengthening and mechanical shot peening composite process according to claim 7, characterized in that: The inspection includes tensile, fatigue, hardness and other tests, and TEM, SEM and EBSD analyses are performed on the microstructure after inspection.

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