Method for strengthening mechanical property of complex surface based on laser shock strengthening technology

Abstract

The invention provides a method for strengthening the mechanical property of a complex surface based on a laser shock strengthening technology, and belongs to the technical field of laser shock strengthening. The method for strengthening the mechanical property of the complex surface based on the laser shock strengthening technology comprises the following steps that the surface of a substrate material is pretreated through femtosecond laser, then an absorption layer and a restraint layer are sequentially arranged on the pretreated surface of the substrate material, and finally first laser shock strengthening is conducted on the surface of the substrate material, and the substrate material with strengthened complex surface mechanical properties is obtained. According to the method, femtosecond laser is adopted to pretreat the surface of the substrate material to enable the surface of the substrate material to present uniformly-arranged recesses, and then the surface of the substrate material is strengthened for multiple times by adopting a multiple-time laser shock strengthening technology, so that various properties of the surface of the substrate material are improved to different degrees; and the technical effect of improving the comprehensive complex mechanical property of the surface of the substrate material is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of laser shock peening, and in particular to a method for strengthening mechanical properties of complex surfaces based on the laser shock peening technology. Background Art

[0002] In modern industry, surface strengthening of materials is crucial to improve their wear resistance, corrosion resistance and service life. Traditional surface treatment methods often have the disadvantages of complex processes, low efficiency or unsatisfactory results. In recent years, laser shock peening technology has attracted widespread attention due to its high efficiency and simplicity.

[0003] Laser shock peening is a surface strengthening technology that uses high-intensity compressive stress shock waves generated when a high-energy pulsed laser beam is irradiated on the metal to impact and plastically deform the metal. When the laser beam is irradiated on the metal surface, the metal surface quickly absorbs the laser energy and heats to the vaporization temperature, causing the metal surface material to suddenly vaporize and generate extremely high compressive stress. This compressive stress propagates inside the metal in the form of a shock wave, causing the metal surface to plastically deform, thereby changing the structure and mechanical properties of the metal surface. Laser shock peening is a non-contact processing method that avoids the mechanical friction and wear in traditional processing methods, thereby ensuring processing accuracy and surface quality.

[0004] Laser shock peening technology has broad application prospects in aerospace, national defense, shipbuilding, nuclear industry, petrochemical industry, biomedicine, rail transportation, power grid and other fields. Especially in improving the performance of core components, laser shock peening technology can significantly improve the material's fatigue resistance, wear resistance and corrosion resistance, thereby improving the quality and life of the product.

[0005] In actual production, different fields have different requirements for the surface mechanical properties of components. The existing methods can only improve the surface performance of some components, but it is difficult to improve all surface properties to a certain extent, thereby improving the comprehensive performance of the components.

[0006] Based on this, it is of great practical significance to provide a method that can improve the mechanical properties of complex surfaces of components in different fields. Summary of the invention

[0007] The purpose of the present invention is to provide a method for strengthening the mechanical properties of complex surfaces based on laser shock peening technology, aiming to solve the technical problem that the laser shock peening technology in the prior art can only improve a single performance of the component surface but cannot uniformly improve its comprehensive performance.

[0008] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0009] The present invention provides a method for strengthening the mechanical properties of complex surfaces based on laser shock peening technology, comprising the following steps:

[0010] Pre-treating the surface of the substrate material by using a femtosecond laser to obtain a pre-treated substrate material;

[0011] sequentially arranging an absorption layer and a constraint layer on the surface of the pretreated base material to obtain a base material with a coating;

[0012] The surface of the base material with the coating is subjected to a first laser shock strengthening to obtain a base material with enhanced complex surface mechanical properties.

[0013] Furthermore, the pretreatment parameters are: laser pulse width of 35 to 40 femtoseconds, laser wavelength of 800 to 900nm, laser power of 0.5 to 2.5W, single pulse energy of 0.2 to 9μJ, pulse laser beam diameter of 1 to 1.2cm, and scanning times of 1 to 3 times.

[0014] Furthermore, the absorption layer is a black tape.

[0015] Furthermore, the absorption layer has a thickness of 20 to 50 μm.

[0016] Furthermore, the constraint layer is made of organic glass.

[0017] Furthermore, the thickness of the constrained layer is 1.5 to 3 mm.

[0018] Furthermore, the wavelength of the laser shock of the first laser shock strengthening is 800-1200nm, the pulse width range is 10-30ns, the laser spot diameter is 2-6mm, the laser scanning speed is 0.5-1.5mm / s, the scanning interval is 0.75-1.25mm, and the number of times is 2-4.

[0019] Furthermore, after the first laser shock strengthening, the base material is cooled and cleaned.

[0020] Furthermore, the femtosecond laser shock peening and the first laser shock strengthening are both performed in an argon atmosphere.

[0021] The present invention also provides the application of the method for strengthening complex surface mechanical properties based on laser shock strengthening technology described in the above technical solution in improving the surface properties of metal materials.

[0022] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0023] The present invention uses a femtosecond laser to pretreat the surface of the base material before performing laser shock strengthening on the base material, so that the surface of the base material presents uniformly arranged depressions, and forms a compressive residual stress of a certain depth on the surface by changing the surface structure, thereby significantly improving the material's fatigue resistance, bonding strength, mechanical strength and other properties; the present invention arranges an absorption layer and a constraint layer on the surface after using the femtosecond laser, and the laser passes through the constraint layer to irradiate the absorption layer. The absorption layer absorbs the laser energy and quickly vaporizes, while forming a large amount of high-temperature and high-pressure plasma. The plasma quickly expands to form a high-intensity shock wave, and the shock wave enters the surface layer of the material matrix, thereby strengthening the surface of the material matrix. The present invention significantly improves the comprehensive and complex mechanical properties of the surface through multiple laser shock strengthening. DETAILED DESCRIPTION

[0024] The present invention provides a method for strengthening the mechanical properties of complex surfaces based on laser shock peening technology, comprising the following steps:

[0025] Pre-treating the surface of the substrate material by using a femtosecond laser to obtain a pre-treated substrate material;

[0026] sequentially arranging an absorption layer and a constraint layer on the surface of the pretreated base material to obtain a base material with a coating;

[0027] The surface of the base material with the coating is subjected to a first laser shock strengthening to obtain a base material with enhanced complex surface mechanical properties.

[0028] Pre-treating the surface of the substrate material by using a femtosecond laser to obtain a pre-treated substrate material;

[0029] The present invention pre-treats the surface of the substrate material by femtosecond laser, so that the surface of the substrate material presents uniformly arranged depressions, and forms a certain depth of compressive residual stress on the surface by changing the surface structure, which significantly improves the material's fatigue resistance, bonding strength, mechanical strength and other properties.

[0030] In the present invention, the parameters of the pretreatment are preferably: laser pulse width of 35 to 40 femtoseconds, laser wavelength of 800 to 900nm, laser power of 0.5 to 2.5W, single pulse energy of 0.2 to 9μJ, pulse laser beam diameter of 1 to 1.2cm, and number of scans of 1 to 3 times; further preferably: laser pulse width of 35 to 38 femtoseconds, laser wavelength of 800 to 850nm, laser power of 0.5 to 1.5W, single pulse energy of 0.2 to 4μJ, pulse laser beam diameter of 1 to 1.1cm, and number of scans of 1 to 2 times.

[0031] sequentially arranging an absorption layer and a constraint layer on the surface of the pretreated base material to obtain a base material with a coating;

[0032] During laser shock treatment, the laser passes through the confinement layer and irradiates the absorption layer. The absorption layer absorbs the laser energy and quickly vaporizes, forming a large amount of high-temperature and high-pressure plasma. The plasma quickly expands to form a high-intensity shock wave, which enters the surface of the material matrix, thereby strengthening the surface of the material matrix. The present invention preferably also specifically limits the composition and thickness of the confinement layer and the absorption layer.

[0033] In the present invention, the absorption layer is preferably a black tape.

[0034] In the present invention, the thickness of the absorption layer is preferably 20 to 50 μm, and more preferably 20 to 30 μm.

[0035] In the present invention, the constraining layer is preferably organic glass.

[0036] In the present invention, the thickness of the constrained layer is preferably 1.5 to 3 mm, and more preferably 1.5 to 2 mm.

[0037] In the present invention, the parameters of the first laser shock strengthening are preferably: the wavelength of the laser shock is 800-1200nm, the pulse width range is 10-30ns, the laser spot diameter is 2-6mm, the laser scanning speed is 0.5-1.5mm / s, the scanning interval is 0.75-1.25mm, and the number of times is 2-4 times; further preferably: the wavelength of the laser shock is 800-1000nm, the pulse width range is 10-20ns, the laser spot diameter is 2-4mm, the laser scanning speed is 0.5-1.0mm / s, the scanning interval is 0.75-1.00mm, and the number of times is 2-3 times.

[0038] The present invention improves the comprehensive mechanical properties of the surface of the base material through multiple laser shock peening treatments, which can significantly improve its corrosion resistance, toughness, mechanical strength and other properties.

[0039] In the present invention, the first laser shock peening preferably further includes cooling and cleaning the base material.

[0040] After the laser shock peening treatment, the surface is cleaned, and the absorption layer and the constraint layer are removed to obtain the target product. In the present invention, the technical means for cleaning are not particularly limited, and the technical means that are familiar to those skilled in the art and can achieve the cleaning effect can be used.

[0041] In the present invention, the femtosecond laser shock processing and the first laser shock strengthening are preferably both performed in an argon atmosphere.

[0042] The present invention also provides the application of the method for strengthening complex surface mechanical properties based on laser shock strengthening technology described in the above technical solution in improving the surface properties of metal materials.

[0043] In the present invention, unless otherwise specified, the required raw materials for preparation are all commercially available products well known to those skilled in the art.

[0044] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0045] Example 1

[0046] (1) Select the base material to be strengthened, clean and dry the surface of the base material, remove impurities on the surface, and keep it dry and tidy;

[0047] (2) In an argon protective atmosphere, the substrate material is treated with a femtosecond laser once with a limited pulse width of 35 femtoseconds, a laser wavelength of 800nm, a laser power of 0.5W, a single pulse energy of 0.2μJ, and a pulse laser beam diameter of 1cm. After the femtosecond laser treatment, the surface of the substrate material exhibits uniformly arranged depressions;

[0048] (3) Then, the surface of the substrate is covered with a 20 μm black tape and a 1.5 mm plexiglass in sequence;

[0049] (4) Then, the laser shock peening treatment is performed again in an argon protective atmosphere with a wavelength of 800 nm, a pulse width of 10 ns, a laser spot diameter of 2 mm, a laser scanning speed of 0.5 mm / s, and a scanning interval of 0.75 mm to perform laser shock peening on the substrate material;

[0050] (5) After the laser shock peening treatment is completed, the base material is cooled to room temperature, and the constraining layer and the absorbing layer are removed to obtain a base material with enhanced complex surface mechanical properties.

[0051] Example 2

[0052] (1) Select the base material to be strengthened, clean and dry the surface of the base material, remove impurities on the surface, and keep it dry and tidy;

[0053] (2) In an argon protective atmosphere, the substrate material was treated with femtosecond laser twice with a limited pulse width of 38 femtoseconds, a laser wavelength of 850nm, a laser power of 1.5W, a single pulse energy of 0.4μJ, and a pulse laser beam diameter of 1.1cm. After the femtosecond laser treatment, the surface of the substrate material showed uniformly arranged depressions;

[0054] (3) Then, the surface of the substrate is covered with 30 μm black tape and 2 mm organic glass in sequence;

[0055] (4) Then, the laser shock peening treatment is performed again in an argon protective atmosphere with a wavelength of 1000 nm, a pulse width of 20 ns, a laser spot diameter of 4 mm, a laser scanning speed of 1.0 mm / s, and a scanning interval of 1.00 mm to perform laser shock peening on the substrate material;

[0056] (5) After the laser shock peening treatment is completed, the substrate material is cooled to room temperature, and the constraining layer and the absorbing layer are removed to obtain a substrate material with enhanced complex surface mechanical properties.

[0057] Example 3

[0058] (1) Select the base material to be strengthened, clean and dry the surface of the base material, remove impurities on the surface, and keep it dry and tidy;

[0059] (2) In an argon protective atmosphere, the substrate material was treated with femtosecond laser three times with a limited pulse width of 40 femtoseconds, a laser wavelength of 900nm, a laser power of 2.5W, a single pulse energy of 9μJ, and a pulse laser beam diameter of 1.2cm. After the femtosecond laser treatment, the surface of the substrate material showed uniformly arranged depressions;

[0060] (3) Then, the surface of the substrate is covered with 50 μm black tape and 3 mm organic glass in sequence;

[0061] (4) Then, the laser shock peening treatment is performed again in an argon protective atmosphere with a wavelength of 1200 nm, a pulse width of 30 ns, a laser spot diameter of 6 mm, a laser scanning speed of 1.5 mm / s, and a scanning interval of 1.25 mm to perform laser shock peening on the substrate material;

[0062] (5) After the laser shock peening treatment is completed, the base material is cooled to room temperature, and the constraining layer and the absorbing layer are removed to obtain a base material with enhanced complex surface mechanical properties.

[0063] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for strengthening the mechanical properties of complex surfaces based on laser shock peening technology, characterized in that: The following steps are involved: Pre-treating the surface of the substrate material by using a femtosecond laser to obtain a pre-treated substrate material; sequentially arranging an absorption layer and a constraint layer on the surface of the pretreated base material to obtain a base material with a coating; The surface of the base material with the coating is subjected to a first laser shock strengthening to obtain a base material with enhanced complex surface mechanical properties.

2. The method for strengthening mechanical properties of complex surfaces based on laser shock peening technology according to claim 1, characterized in that: The pretreatment parameters are: laser pulse width of 35-40 femtoseconds, laser wavelength of 800-900nm, laser power of 0.5-2.5W, single pulse energy of 0.2-9μJ, pulse laser beam diameter of 1-1.2cm, and scanning times of 1-3 times.

3. The method for strengthening mechanical properties of complex surfaces based on laser shock peening technology according to claim 1, characterized in that: The absorption layer is a black tape.

4. The method for strengthening mechanical properties of complex surfaces based on laser shock peening technology according to claim 1, characterized in that: The absorption layer has a thickness of 20 to 50 μm.

5. The method for strengthening mechanical properties of complex surfaces based on laser shock peening technology according to claim 1, characterized in that: The constraining layer is organic glass.

6. The method for strengthening mechanical properties of complex surfaces based on laser shock peening technology according to claim 1, characterized in that: The thickness of the constrained layer is 1.5 to 3 mm.

7. The method for strengthening mechanical properties of complex surfaces based on laser shock peening technology according to claim 1, characterized in that: The wavelength of the laser shock of the first laser shock strengthening is 800-1200nm, the pulse width range is 10-30ns, the laser spot diameter is 2-6mm, the laser scanning speed is 0.5-1.5mm / s, the scanning interval is 0.75-1.25mm, and the number of times is 2-4.

8. The method for strengthening mechanical properties of complex surfaces based on laser shock peening technology according to claim 1, characterized in that: The method further includes cooling and cleaning the base material after the first laser shock peening.

9. The method for strengthening mechanical properties of complex surfaces based on laser shock peening technology according to claim 1, characterized in that: The femtosecond laser shock and the first laser shock strengthening are both performed in an argon atmosphere.

10. Application of the method for strengthening complex surface mechanical properties based on laser shock peening technology as described in any one of claims 1 to 9 in improving the surface properties of metal materials.