Systems and methods for improving the surface quality and mechanical properties of materials

Abstract

This invention discloses a system and method for improving the surface quality and mechanical properties of materials. The method includes laser shock annealing (LSA) of a selected area on the surface of a material to be treated using a pulsed laser to form dislocation pile-ups and / or nanocrystals on the surface; and laser surface treatment of the treated area on the surface of the material to be treated using a continuous laser to remove at least the dents and / or cracks formed after LSA. The method for improving the surface quality and mechanical properties of materials provided by this invention can improve the surface quality of materials after LSA and further enhance the mechanical properties of the LSA surface, thus promoting the practical application of LSA.

Description

Technical Field

[0001] This invention relates in particular to a system and method for improving the surface quality and mechanical properties of materials, belonging to the field of laser processing technology. Background Technology

[0002] Laser shock peening (LSP), also known as laser shot peening, is an advanced technology that uses a nanosecond short-pulse high-energy laser beam to modify the surface of a workpiece by impacting it with a physical shot. After laser shock peening, the intensity of the generated shock wave is much higher than the elastic yield limit of most materials. This leads to grain refinement, residual compressive stress formation, and increased dislocation density within a certain depth of the material surface. These effects inhibit the initiation and development of fatigue cracks, significantly extend the fatigue life of the material, and improve its mechanical properties.

[0003] The principle of laser surface treatment is to rapidly scan the workpiece with a high-energy laser beam, causing the temperature of the irradiated metal surface to rise rapidly, achieving remelting and rapid solidification of the thin surface layer. During laser surface treatment, the laser beam is precisely controlled to directly irradiate the material surface for polishing. The energy and intensity of the laser beam are controlled to precisely melt the peaks and valleys of the surface, and the molten material is evenly distributed at the bottom of the valleys due to surface tension and gravity in multiple directions. Laser surface treatment not only improves the surface mechanical properties of parts but also reduces surface roughness.

[0004] During laser shock strengthening, the material surface undergoes severe plastic deformation due to the shock wave, forming protrusions and depressions, i.e., numerous "peaks" and "valleys." This further increases the surface roughness of the original metal, which already has a low surface finish. Research from the Air Force Engineering University shows that after laser shock strengthening, the Ra value of smooth stainless steel with a surface finish of 419 nm becomes 584 nm. Moreover, the greater roughness makes it difficult for adjacent layers to form a tight remelting, resulting in poor interlayer bonding and large interlayer unfusion defects. These defects can become crack initiation points, making it difficult to meet the industrial standard requirements for parts.

[0005] Laser shock annealing (LSU) often results in low surface quality, significantly impacting corrosion resistance and tensile strength, thus limiting its practical application. To further expand its applications, researchers have conducted extensive studies on process optimization. However, research on composite LSU processes is limited. Wenzhou University (CN103060528A) proposed a composite laser annealing process comprising four steps: laser micromachining, laser shock annealing, surface coating, and laser shock wave microtexturing. This process significantly improves residual compressive stress, wetting characteristics, heat transfer, cooling, and lubrication in the cutting edge region, mitigates the formation of built-up edge and burrs, and enhances the adhesion of nickel-based materials to the tool surface, extending tool life and improving machining quality stability. Jiangsu University (CN109207906A) proposed a laser high-temperature shock nitriding composite machining device and method. First, the material undergoes a high-temperature, high-pressure nitriding treatment using a nitriding system, forming a nitrided layer of a certain depth on the sample surface. Then, the nitriding furnace is depressurized, and the internal temperature is adjusted and maintained according to the temperature requirements of the material's dynamic time-dependent changes. A laser high-temperature shock blasting system is then activated to perform a first shock strengthening process on the material surface, generating a high density of dislocations, dislocation entanglements, and subgrain boundaries, and inducing a high-temperature phase transition reaction between nitrogen atoms and metal atoms. A second nitriding and a second laser shock blasting can then be performed.

[0006] Currently, research on laser shock strengthening composite processes mainly focuses on the combination of laser with surface treatments such as nitriding, while research on multi-laser composite shock strengthening is scarce. Summary of the Invention

[0007] The main objective of this invention is to provide a system and method for improving the surface quality and mechanical properties of materials, thereby overcoming the shortcomings of the prior art.

[0008] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0009] This invention provides a method for improving the surface quality and mechanical properties of materials, comprising:

[0010] A pulsed laser is used to perform laser shock peening on a selected area of ​​the surface of the material to be treated, so as to form dislocation pile-up and / or nanocrystals on the surface of the material to be treated; a continuous laser is used to perform laser surface treatment on the processed area of ​​the surface of the material to be treated after shock peening, so as to at least remove the dents and / or cracks formed after laser shock peening.

[0011] This invention also provides an all-laser composite impact strengthening system for implementing the method described above for improving material surface quality and mechanical properties. The all-laser composite impact strengthening system includes:

[0012] A laser shock blasting unit includes a pulsed laser and a laser shock blasting head, wherein the pulsed laser is at least used to provide pulsed laser light, and the laser shock blasting head is at least used to output the pulsed laser light.

[0013] A laser surface treatment unit includes a continuous laser and a scanning galvanometer, wherein the continuous laser is used at least to provide continuous laser light, and the scanning galvanometer is used at least to adjust the incident angle and scanning path of the continuous laser light.

[0014] A composite impact head is disposed between the pulsed laser, the continuous laser, the laser shock enhancement head, and the scanning galvanometer, and is at least used to guide the pulsed laser provided by the pulsed laser to the laser shock enhancement head and to guide the continuous laser provided by the continuous laser to the scanning galvanometer.

[0015] A motion control unit is connected to the laser shock strengthening head and is used at least to drive the laser shock strengthening head to move along a selected trajectory;

[0016] The control unit is connected to the laser shock strengthening unit, the laser surface treatment unit, and the motion control unit.

[0017] Compared with the prior art, the advantages of the present invention include: the method for improving the surface quality and mechanical properties of materials provided by the embodiments of the present invention can improve the surface quality of materials after laser shock strengthening treatment, and at the same time can further enhance the mechanical properties of the laser shock strengthened surface, which has a certain promoting effect on the practical application of laser shock strengthening. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of an all-laser composite impact strengthening system provided in a typical embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram illustrating the principle of a method for improving the surface quality and mechanical properties of materials according to an embodiment of the present invention;

[0020] Figure 3a , Figure 3b These are schematic diagrams of the surface roughness of materials treated by traditional laser shock peening process and by the all-laser composite shock peening process provided in this embodiment of the invention, respectively.

[0021] Figure 4 The surface microhardness of untreated materials, materials that have only undergone laser shock annealing, and materials that have undergone full laser composite shock annealing.

[0022] Figure 5 This is a surface roughness diagram of the material after processing in Comparative Example 1;

[0023] Figure 6This is a surface roughness diagram of the material after processing in Comparative Example 2. Detailed Implementation

[0024] In view of the shortcomings of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The following will further explain and illustrate this technical solution, its implementation process, and its principles.

[0025] Explanation of technical terms involved in the embodiments of the present invention: During the laser surface treatment process, the energy generated by the laser will cause the surface material to melt, and the molten pool is the central part of the material melting.

[0026] This invention provides a method for improving the surface quality and mechanical properties of materials, comprising:

[0027] A pulsed laser is used to perform laser shock peening on a selected area of ​​the surface of the material to be treated, so as to form dislocation pile-up and / or nanocrystals on the surface of the material to be treated; a continuous laser is used to perform laser surface treatment on the processed area of ​​the surface of the material to be treated after shock peening, so as to at least remove the dents and / or cracks formed after laser shock peening.

[0028] In some more specific implementations, the method specifically includes: using the pulsed laser to perform laser shock strengthening treatment on a selected area of ​​the surface of the material to be treated during a first time period, and using the continuous laser to perform laser surface treatment on the processed area of ​​the surface of the material to be treated after laser shock strengthening treatment for at least a portion of the first time period.

[0029] In some more specific implementations, the method specifically includes: using a pulsed laser to perform impact strengthening treatment on at least a selected area of ​​the surface of the material to be treated during a first time period; and using a continuous laser to perform laser surface treatment on the processed area of ​​the surface of the material to be treated after impact strengthening treatment during a second time period, wherein the second time period is after the first time period.

[0030] In some more specific implementations, the method specifically includes: repeatedly performing laser shock peening treatment and laser surface treatment on the surface of the material to be treated two or more times.

[0031] In some more specific implementations, the laser surface treatment includes laser polishing or laser surface remelting.

[0032] In some more specific embodiments, the method includes performing the laser surface treatment under a protective atmosphere, the protective atmosphere including a nitrogen atmosphere or an inert gas atmosphere.

[0033] In some more specific implementations, the method includes: using a pulsed laser to impact a selected area of ​​the surface of the material to be treated 1-100 times.

[0034] In some more specific implementations, the wavelength of the pulsed laser is 510-530nm, the energy of a single pulse of the pulsed laser is 0-3J, and the pulse width is 10-20ns.

[0035] In some more specific embodiments, the energy density of the pulsed laser is 0.1-100 GW / cm². 2 The overlap rate of the light spots is 1-99%.

[0036] In some more specific implementations, the continuous laser has a laser power of 50-1000W, a scanning speed of 10-2000mm / s, a fill spacing of 0.005-0.1mm, and a defocusing amount of -10-10mm.

[0037] In some more specific implementations, the wavelength of the continuous laser is 1050-1070 nm.

[0038] This invention also provides an all-laser composite impact strengthening system for implementing the method described above for improving material surface quality and mechanical properties. The all-laser composite impact strengthening system includes:

[0039] A laser shock blasting unit includes a pulsed laser and a laser shock blasting head, wherein the pulsed laser is at least used to provide pulsed laser light, and the laser shock blasting head is at least used to output the pulsed laser light.

[0040] A laser surface treatment unit includes a continuous laser and a scanning galvanometer, wherein the continuous laser is used at least to provide continuous laser light, and the scanning galvanometer is used at least to adjust the incident angle and scanning path of the continuous laser light.

[0041] A composite impact head is disposed between the pulsed laser, the continuous laser, the laser shock enhancement head, and the scanning galvanometer, and is at least used to guide the pulsed laser provided by the pulsed laser to the laser shock enhancement head and to guide the continuous laser provided by the continuous laser to the scanning galvanometer.

[0042] A motion control unit is connected to the laser shock strengthening head and is used at least to drive the laser shock strengthening head to move along a selected trajectory;

[0043] The control unit is connected to the laser shock strengthening unit, the laser surface treatment unit, and the motion control unit.

[0044] It should be noted that the function of the composite impact head is to integrate the optical paths of the two processes. By integrating the optical paths, the two processes can be connected more tightly, improving processing accuracy and efficiency and reducing positioning errors. The scanning galvanometer is part of the laser surface treatment unit. After the laser comes out of the laser, it enters the scanning galvanometer through the optical path. The deflection of the scanning galvanometer enables laser surface treatment of different areas of the surface of the material to be treated.

[0045] In some more specific implementations, the all-laser composite shock strengthening system further includes an auxiliary unit, which is also connected to the control unit. The auxiliary unit includes an ultrapure water circulation mechanism, a laser cooling water supply mechanism, and an atmosphere protection mechanism. The ultrapure water circulation mechanism is at least used to provide ultrapure water to form a water film as a constraint layer during the laser shock strengthening process. The laser cooling water supply mechanism is at least used to circulate water to cool the laser. The atmosphere protection mechanism is at least used to provide different gas atmospheres during the laser surface treatment process.

[0046] In some more specific implementations, the all-laser composite impact strengthening system further includes a motion platform, which is at least used to place the material to be treated.

[0047] The following will further explain the technical solution, its implementation process and principle in conjunction with the accompanying drawings and specific implementation examples. Unless otherwise specified, the laser, controller, scanning galvanometer, motion platform and other components used in the embodiments of the present invention are all known to those skilled in the art, and their specific structures and models are not limited here.

[0048] Example 1

[0049] Please see Figure 1 A fully laser-based composite impact strengthening system includes a control unit 1, a motion control unit 2, a laser surface treatment unit 3, a laser impact strengthening unit 4, an auxiliary unit 5, and a motion platform 10.

[0050] The motion platform 10 is used to place the material to be treated 9. The motion control unit 2, laser surface treatment unit 3, laser shock blasting unit 4, and auxiliary unit 5 are respectively connected to the control unit 1. The laser surface treatment unit 3 is used to provide continuous laser to perform laser surface treatment on the material to be treated 9. The laser shock blasting unit 4 is used to provide pulsed laser to perform laser shock blasting treatment on the material to be treated 9. The motion control unit 2 and the laser shock blasting unit 4 are driven together so that the laser shock blasting unit 4 can treat different areas of the surface of the material to be treated 9. The auxiliary unit 5 is used to provide ultrapure water to the surface of the material to be treated 9, cool the laser surface treatment unit 3 and the laser shock blasting unit 4, and provide a protective atmosphere to the surface of the material to be treated 9. The control unit 1 is used to regulate the working status and working parameters of the motion control unit 2, the laser surface treatment unit 3, the laser shock blasting unit 4, and the auxiliary unit 5.

[0051] The scanning galvanometer 7 and the laser shock strengthening head 8 are respectively used to incident the continuous laser provided by the laser surface treatment unit 3 and the pulsed laser provided by the laser shock strengthening unit 4 onto the material to be treated 9. The scanning galvanometer 7 and the laser shock strengthening head 8 are respectively corresponding to the laser surface treatment unit 3 and the laser shock strengthening unit 4 on the composite shock head 6.

[0052] Furthermore, the motion control unit 2 and the auxiliary unit 5 are also connected to the composite impact head 6. The motion control unit 2 is used to drive the composite impact head 6 to move along a selected trajectory, and the auxiliary unit 5 is used to provide ultrapure water or atmosphere protection.

[0053] In this embodiment, the laser surface treatment unit 3 includes at least one continuous laser and a scanning galvanometer 7. The continuous laser is used to provide continuous laser light, and the scanning galvanometer 7 is disposed in the optical path of the continuous laser light. The scanning galvanometer 7 is used at least to adjust the incident angle of the continuous laser light. The scanning galvanometer 7 can be a two-dimensional scanning galvanometer or a three-dimensional scanning galvanometer, etc. The laser shock strengthening unit 4 includes at least one pulsed laser and a laser shock strengthening head 8. The pulsed laser is used to provide pulsed laser light, and the laser shock strengthening head is used at least to output the pulsed laser light.

[0054] In this embodiment, the motion control unit 2 is connected to the laser shock enhancement head 8 via a transmission connection, and the motion control unit 2 may be an XY translation mechanism, etc.

[0055] In this embodiment, a composite impact head 6 is also provided between the pulsed laser, the continuous laser, the laser shock enhancement head, and the scanning galvanometer. The composite impact head 6 is at least used to guide the pulsed laser provided by the pulsed laser to the laser shock enhancement head and to guide the continuous laser provided by the continuous laser to the scanning galvanometer.

[0056] In this embodiment, the composite impact head 6 integrates the optical paths of the two processes. Optical path integration makes the connection between the two processes more compact, improves processing accuracy and efficiency, and reduces positioning errors. The scanning galvanometer is part of the laser surface treatment unit. After the laser comes out of the laser, it enters the scanning galvanometer through the optical path and performs laser surface treatment by deflection of the scanning galvanometer. The laser shock strengthening unit controls the laser to output pulsed laser through the control system. The output pulsed laser is then transmitted to the laser shock strengthening head through the optical path. At the same time, the control system's motion system drives the laser shock strengthening head to work.

[0057] In this embodiment, the continuous laser and pulsed laser can be lasers capable of providing various pulse widths, wavelengths, frequencies, and energies, and the provided continuous laser and pulsed laser can be lasers of different wavelengths such as infrared light and green light.

[0058] In this embodiment, the auxiliary unit includes an ultrapure water circulation mechanism, a laser cooling water mechanism, and an atmosphere protection mechanism. The ultrapure water circulation mechanism provides ultrapure water as a water film to act as a constraint layer during the laser shock peening process and sprays water on the processing area during the laser shock peening process. The laser cooling water mechanism is mainly used to cool the laser. The atmosphere protection mechanism is mainly used to protect the surface to be treated with different gas atmospheres during the laser surface treatment process.

[0059] Please see Figure 2 A method to improve the surface quality and mechanical properties of materials can be adopted. Figure 1 The implementation of a full laser composite impact strengthening system may specifically include the following steps:

[0060] To form dislocation pile-up and / or nanocrystals on the surface of the material to be treated; to perform laser surface treatment on the processed area of ​​the surface of the material to be treated after impact strengthening treatment using a continuous laser, so as to at least remove the dents and / or cracks formed after laser impact strengthening treatment; to perform laser surface treatment on the processed area of ​​the surface of the material to be treated after impact strengthening treatment using a continuous laser, so as to at least remove the dents and / or cracks formed after laser impact strengthening treatment.

[0061] In this embodiment, the impact strengthening treatment and laser surface treatment can be performed simultaneously or in steps. For example, the pulsed laser can be used to perform laser impact strengthening treatment on a selected area of ​​the surface of the material to be treated during a first time period, and the continuous laser can be used to perform laser surface treatment on the processed area of ​​the surface of the material to be treated after laser impact strengthening treatment for at least a portion of the first time period. Alternatively, the pulsed laser can be used to perform impact strengthening treatment on at least a selected area of ​​the surface of the material to be treated during the first time period, and the continuous laser can be used to perform laser surface treatment on the processed area of ​​the surface of the material to be treated after impact strengthening treatment during a second time period, wherein the second time period is after the first time period.

[0062] In this embodiment, when performing laser shock strengthening treatment on the surface of the material to be treated, the pulsed laser is perpendicular to the surface of the material to be treated; and when performing laser surface treatment on the surface of the material to be treated, the continuous laser is perpendicular to the surface of the material to be treated.

[0063] In this embodiment, the laser shock peening treatment and the laser surface treatment can be performed in one cycle or multiple cycles. One cycle includes the laser shock peening treatment and the laser surface treatment.

[0064] In this embodiment, the laser shock peening treatment can be performed by shocking a selected area of ​​the surface of the material to be treated with a pulsed laser 1-100 times. The wavelength of the pulsed laser is 510-530 nm, the energy of a single pulse is 0-3 J, the pulse width is 10-20 ns, and the energy density of the pulsed laser is 0.1-100 GW / cm². 2 The overlap rate of the light spots is 1-99%.

[0065] In this embodiment, the laser surface treatment includes laser polishing or laser surface remelting. The continuous laser used for laser surface treatment has a laser power of 50-1000W, a scanning speed of 10-2000mm / s, a fill spacing of 0.005-0.1mm, a defocusing amount of -10-10mm, and a wavelength of 1050-1070nm.

[0066] In this embodiment, an atmosphere protection can be used during the laser surface treatment, and the protective atmosphere may include a nitrogen atmosphere or an inert gas atmosphere.

[0067] Please refer to it again. Figure 2When laser shock annealing is performed on materials with pulsed lasers, shock waves of up to several GPa can be generated in a single pass. These shock waves can significantly refine the grains on the material surface, and the high-energy shock waves cause a large number of dislocation pile-ups and nanocrystals to form on the material surface, thereby improving the surface hardness, introducing larger residual compressive stress, and improving the fatigue life and corrosion resistance of the material. However, laser shock annealing is prone to producing defects such as surface indentations and cracks on the material surface, which have a certain impact on the corrosion resistance and tensile strength of the material surface. Often, sandpaper is needed to remove the surface indentations and cracks. Laser surface treatment technology can achieve the remelting and rapid solidification of thin surface layers. By controlling the laser energy input, defects such as indentations and cracks on the surface of the material after laser shock annealing can be melted, which can further improve the surface quality and mechanical properties of the material.

[0068] The inventors of this invention discovered that the effect of laser surface treatment after impact strengthening on improving surface quality and mechanical properties is uncertain. Laser impact strengthening is a cold deformation process, while laser surface treatment is a hot deformation process. These two processes alter the material's microstructure in different ways, resulting in a composite process that can simultaneously achieve both cold and hot deformation of a material. Different materials and different laser treatment parameters yield different results. First, laser impact strengthening refines the material's surface microstructure and improves its mechanical properties, but it can also lead to defects such as surface cracks and dents, which are detrimental to the material's direct application. Laser surface treatment following laser impact strengthening can resolve these surface defects and, through the rapid heating and cooling effect of the laser, achieve rapid heat treatment of the material's surface, further enhancing its surface properties. In the all-laser composite impact strengthening process provided in this invention, laser impact strengthening alters the material's microstructure through cold deformation, while laser surface treatment further alters the microstructure through remelting heat treatment, thereby further influencing the material's surface mechanical properties. The resulting microstructure is entirely different from that obtained by either laser impact strengthening or laser surface treatment alone.

[0069] Example 2

[0070] Using TC4 titanium alloy as the material to be treated, a pulsed laser with a wavelength of 530nm, a single pulse energy of 3J, and a pulse width of 10ns is used as the light source for laser shock peening, and a continuous laser with a wavelength of 1064nm and a laser power of 1000W is used as the heat source for surface treatment. This combination forms a laser shock-laser surface treatment process for TC4 titanium alloy, which specifically includes the following steps:

[0071] 1) Grind the surface of the TC4 titanium alloy material until smooth and clean it with alcohol or similar substances;

[0072] 2) TC4 titanium alloy material is subjected to laser shock strengthening treatment with a 50% overlap rate. The laser energy density of the laser shock strengthening treatment is 0.1-100 GW / cm². 2 The light spot overlap rate is 1-99%, and the number of impacts is 1-100.

[0073] 3) After laser shock hardening, laser surface treatment is performed directly. The laser power for laser surface treatment is 50-1000W, the scanning speed is 10-2000mm / s, the fill gap is 0.005-0.1mm, and the defocusing amount is -10-10mm.

[0074] 4) After completion, shut down all equipment to complete the laser shock and surface treatment coupled strengthening process.

[0075] After testing and comparison, such as Figure 3a , Figure 3b As shown, the surface roughness of the material after laser shock strengthening is Ra11.18μm, and the surface roughness of the material after laser surface treatment is reduced to Ra0.70μm, indicating a significant improvement in surface quality.

[0076] The inventors also tested the microhardness of untreated TC4 titanium alloy, TC4 titanium alloy treated with laser shock peening, and TC4 titanium alloy treated with full laser composite shock peening, respectively. The test results are as follows: Figure 4 As shown, the final microhardnesses of the materials were 381.29 Hv, 430.11 Hv, and 821.60 Hv, respectively. Obviously, after full laser composite impact strengthening, the microhardness of the material was increased by 115% and 91% compared with the original material and the material that only underwent impact strengthening treatment, respectively, and the surface microhardness of the material was significantly improved.

[0077] Comparative Example 1

[0078] The processing techniques of Comparative Example 1 and Example 2 are basically the same, except that:

[0079] Comparative Example 1 uses laser energy density of 0.1-100 GW / cm² during laser shock peening treatment. 2 The laser spot overlap rate is 1-99%, the number of impacts is 1-100; the laser power for laser surface treatment is 10-50W, the scanning speed is 2000-5000mm / s, the filling gap is 0.1-0.5mm, and the defocusing amount is -10-10mm.

[0080] The TC4 titanium alloy material treated in Comparative Example 1 was tested, and the results were as follows: Figure 5As shown, if the input energy during laser surface treatment is too low, the conditions for material sublimation or melting cannot be met, resulting in the failure to remove surface defects after laser shock strengthening, leading to deteriorated surface properties. Furthermore, insufficient energy input prevents the alteration of the material's microstructure after laser surface treatment, thus failing to achieve the desired composite strengthening effect. Therefore, only when the laser surface treatment input energy is appropriate can both the surface quality and the microstructure be altered to improve surface properties.

[0081] Comparative Example 2

[0082] The processing technology of Comparative Example 2 is basically the same as that of Example 2, except that the laser energy density of Comparative Example 2 in the laser shock strengthening treatment is 0.1-100 GW / cm². 2 The laser spot overlap rate is 1-99%, the number of impacts is 1-100, the laser power for laser surface treatment is 1000-5000W, the scanning speed is 1-10mm / s, the filling gap is 0.1-1mm, and the defocusing amount is -10-10mm.

[0083] The TC4 titanium alloy material treated in Comparative Example 1 was tested, and the results were as follows: Figure 6 As shown, excessively high input energy during laser surface treatment exceeds the conditions for material sublimation or melting, leading to increased surface defects after laser shock strengthening and consequently deterioration of surface properties. Furthermore, excessively high energy input reaches the material's failure point after laser surface treatment, further introducing more defects and thus failing to achieve the desired composite strengthening effect.

[0084] This invention provides a method for improving the surface quality and mechanical properties of materials. Addressing defects such as unevenness and surface cracks on surfaces after laser shock strengthening, this method employs a multi-laser composite approach, performing laser surface treatment after laser shock strengthening, thus resolving the problem of poor material surface quality. This method can improve the surface quality of materials after laser shock strengthening and further enhance the mechanical properties of the laser-strengthened surface, thus promoting the practical application of laser shock strengthening.

[0085] It should be understood that the above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for improving the surface quality and mechanical properties of a material, characterized in that, include: A pulsed laser is used to perform laser shock peening treatment on a selected area of ​​the surface of the material to be treated, so as to form dislocation pile-up and / or nanocrystals on the surface of the material to be treated; A continuous laser is used to remelt the processed area of ​​the material surface after laser shock strengthening treatment, in order to at least remove the dents and / or cracks formed after the laser shock strengthening treatment. The material to be treated is TC4 titanium alloy. The wavelength of the pulsed laser is 510 nm-530 nm, the energy of a single pulse is 0-3 J, the pulse width is 10 ns-20 ns, and the energy density of the pulsed laser is 0.1 GW / cm². 2 -100GW / cm 2 The spot overlap rate is 1%-99%; the wavelength of the continuous laser is 1050 nm-1070 nm, the laser power of the continuous laser is 50 W-1000 W, the scanning speed is 10 mm / s-2000 mm / s, the fill spacing is 0.005 mm-0.1 mm, and the defocus amount is -10 mm-10 mm.

2. The method according to claim 1, characterized in that, Specifically, it includes: The pulsed laser is used to perform laser shock strengthening treatment on a selected area of ​​the surface of the material to be treated during a first time period, and the continuous laser is used to perform laser surface remelting treatment on the processed area of ​​the surface of the material to be treated after laser shock strengthening treatment for at least a part of the first time period.

3. The method according to claim 1, characterized in that... Specifically, it includes: During a first time period, a pulsed laser is used to perform impact strengthening treatment on at least a selected area of ​​the surface of the material to be treated; during a second time period, a continuous laser is used to perform laser surface remelting treatment on the processed area of ​​the surface of the material to be treated after impact strengthening treatment, the second time period being after the first time period.

4. The method according to any one of claims 1-3, characterized in that... include: When performing laser shock hardening treatment on the surface of the material to be treated, the pulsed laser is perpendicular to the surface of the material to be treated; and when performing laser surface remelting treatment on the surface of the material to be treated, the continuous laser is perpendicular to the surface of the material to be treated.

5. The method according to claim 4, characterized in that, The method includes: repeatedly performing laser shock peening treatment and laser surface remelting treatment on the surface of the material to be treated more than twice.

6. The method according to claim 4, characterized in that, The method includes performing the laser surface remelting process under a protective atmosphere, wherein the protective atmosphere includes a nitrogen atmosphere or an inert gas atmosphere.

7. The method according to claim 1, characterized in that... include: A pulsed laser is used to impact a selected area of ​​the surface of the material to be treated 1-100 times.

8. A full laser composite impact strengthening system, used to implement the method for improving the surface quality and mechanical properties of materials according to any one of claims 1-7, characterized in that: The all-laser composite impact strengthening system includes: A laser shock blasting unit includes a pulsed laser and a laser shock blasting head, wherein the pulsed laser is at least used to provide pulsed laser light, and the laser shock blasting head is at least used to output the pulsed laser light. A laser surface treatment unit includes a continuous laser and a scanning galvanometer, wherein the continuous laser is used at least to provide continuous laser light, and the scanning galvanometer is used at least to adjust the incident angle and scanning path of the continuous laser light. A composite impact head is disposed between the pulsed laser, the continuous laser, the laser shock enhancement head, and the scanning galvanometer, and is at least used to guide the pulsed laser provided by the pulsed laser to the laser shock enhancement head and to guide the continuous laser provided by the continuous laser to the scanning galvanometer. A motion control unit is connected to the laser shock strengthening head and is used at least to drive the laser shock strengthening head to move along a selected trajectory; The control unit is connected to the laser shock strengthening unit, the laser surface treatment unit, and the motion control unit.

9. The all-laser composite impact strengthening system according to claim 8, characterized in that, Also includes: An auxiliary unit, which is also connected to the control unit, includes an ultrapure water circulation mechanism, a laser cooling water supply mechanism, and an atmosphere protection mechanism. The ultrapure water circulation mechanism is at least used to provide ultrapure water to form a water film as a constraint layer during the laser shock peening process. The laser cooling water supply mechanism is at least used to spray water to cool the laser. The atmosphere protection mechanism is at least used to provide different gas atmospheres during the laser surface remelting process.

10. The all-laser composite impact strengthening system according to claim 9, characterized in that, Also includes: A motion platform, which is at least used for placing the material to be processed.

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