A laser repair method for 6061 aluminum alloy substrate with low oxygen conductivity and chromatic aberration

Abstract

The present invention relates to a laser repair method for a 6061 aluminum alloy substrate with low oxygen conductivity and chromatic aberration. The present invention includes providing a repair powder, which is composed of the following components: Si: 0.4-0.8wt.%, Mg: 0.8-1.6wt.%, Cu: 0.15-0.4wt.%, Sc: 0.2-0.3wt.%, Zr: 0.08-0.14wt.%, impurity content is less than 1%, and the balance is Al; surface treatment is performed on the defective part of the substrate of the 6061 aluminum alloy to form a flat defective surface; laser cladding parameters are selected according to the defect type, and the repair powder is sent to the defective surface by a powder feeder to perform laser cladding repair, and after each layer of repair is completed, the oxide on the cladding surface is cleaned, and the defocus amount of the laser is adjusted to perform the next layer of cladding operation until the repair is completed; after the repair is completed, the excess cladding material is removed, and a repair surface matching the base material of the substrate is obtained by grinding. The present invention can obtain excellent cladding layer quality, has good mechanical properties, and has small color difference with the parent material matrix after oxygen conduction, thus meeting the appearance requirements.

Description

Technical Field

[0001] The invention relates to the technical field of laser cladding, and in particular to a laser repair method for a 6061 aluminum alloy substrate with low oxygen conductivity and chromatic aberration. Background Art

[0002] The aviation chassis assembly provides a convenient and secure installation location for the modules and electronic components in the electronic controller, and provides an environment for the modules inside the electronic controller to work normally. It must withstand strong vibration and impact, efficient heat dissipation, high electromagnetic shielding effect, and strong tolerance to climatic environments to ensure the safe and reliable operation of the functional modules inside the controller. The chassis is a high-value-added key aviation component with extremely high requirements for surface integrity. During the processing of the chassis, various irregular damage gaps appear on the surface of the chassis due to problems such as clamping, collision, and accidental damage during processing. At the same time, various surface defects generated during field use and maintenance seriously threaten the service performance of the chassis, making it impossible to install and use it, resulting in huge cost waste. Therefore, an effective repair method is developed based on the use characteristics of the chassis to extend the service life of the chassis.

[0003] The mainstream repair methods at present are thermal spraying, TIG welding, brazing, etc. This method usually has a large heat input and is easy to cause deformation of the chassis, making it impossible to install electronic components. At the same time, this method often has poor bonding ability with the substrate. After being subjected to high-frequency vibration during actual use, it often cracks or falls off, causing accidents. The chassis itself has high requirements for appearance consistency, and the obvious color difference after repair often makes it impossible to deliver the product smoothly.

[0004] Laser cladding technology refers to the process of melting the cladding material and the substrate surface layer simultaneously by irradiating the laser beam on the surface of the cladding substrate, and then rapidly solidifying to form a cladding layer with a very low dilution rate and metallurgical bonding with the substrate, which can effectively improve the wear resistance, corrosion resistance, heat resistance, oxidation resistance and other properties of the substrate surface. Repair by laser cladding can meet the requirements of precise geometric repair of irregular defects at various surface locations, and at the same time, by controlling the blending of elements in the alloy powder, the special requirements required for repair can be met.

[0005] At present, AlSi10Mg is the most commonly used powder material for laser cladding and laser additive manufacturing. It has excellent fluidity and mechanical properties, and meets the functional performance requirements of chassis repair. However, due to the high Si element in AlSi10Mg, the repaired part appears black after conductive oxidation, and there is a sudden color difference with the base color. There is no impact on the parts of the chassis that need to be sprayed, but the sudden color difference of some parts that cannot be sprayed cannot meet customer requirements. Repairs using other powders have problems such as poor quality of the cladding layer, high porosity, and even cracks, and the mechanical properties of the repaired workpiece cannot meet the requirements. Summary of the invention

[0006] To this end, the present invention provides a laser repair method for a 6061 aluminum alloy substrate with low oxygen conductivity and color difference, which can obtain excellent cladding layer quality, good forming after laser cladding repair, good mechanical properties and small color difference with the parent material substrate after oxygen conduction, meeting the appearance requirements of the chassis.

[0007] In order to solve the above technical problems, the present invention provides a laser repair method for a 6061 aluminum alloy substrate with low oxygen conductivity and chromatic aberration, comprising:

[0008] S1. Provide a repair powder, wherein the repair powder is composed of the following components: Si: 0.4-0.8wt.%, Mg: 0.8-1.6wt.%, Cu: 0.15-0.4wt.%, Sc: 0.2-0.3wt.%, Zr: 0.08-0.14wt.%, impurity content is less than 1%, and the balance is Al;

[0009] S2. Surface treatment is performed on defective parts of the substrate of the 6061 aluminum alloy to form a smooth defective surface;

[0010] S3, selecting laser cladding parameters according to the defect type, using a powder feeder to deliver the repair powder to the defect surface, performing laser cladding repair, cleaning the oxide on the cladding surface after each layer of repair is completed, and adjusting the laser defocusing amount to perform the next layer of cladding operation until the repair is completed;

[0011] S4. After the repair is completed, remove the excess cladding material and obtain a repair surface that matches the base material of the substrate through grinding.

[0012] In one embodiment of the present invention, the morphology of the defective portion of the substrate includes surface defects, edge defects and corner defects.

[0013] In one embodiment of the present invention, in step S1, the repair powder has a particle size range of 50-150 μm.

[0014] In one embodiment of the present invention, in step S2, surface treatment is performed on defective parts of the substrate of the 6061 aluminum alloy to form a flat defective surface, including:

[0015] When the defect type is a surface defect, use an electric file and an electric wire brush to grind the notch to remove the surface oxide layer, ensure the surface is smooth and flat, and control the chamfers around 100°-140°.

[0016] In one embodiment of the present invention, in step S2, surface treatment is performed on defective parts of the substrate of the 6061 aluminum alloy to form a flat defective surface, including:

[0017] When the defect type is an angle defect or an edge defect, use a file to grind the notch to remove the surface oxide layer and grind the notch into a smooth bevel.

[0018] In one embodiment of the present invention, in step S3, before the repairing powder is uniformly delivered to the defective surface by a powder feeder, the method further comprises:

[0019] The repair powder is placed in a vacuum drying oven and dried at 80-120° C. for 0.8-1.2 h, and added to a powder feeder after cooling.

[0020] In one embodiment of the present invention, in step S3, selecting corresponding laser cladding parameters according to the defect type includes:

[0021] When the defect type is a planar defect, the laser power is 1400-1600W, the laser scanning speed is 8-12mm / s, the defocus amount is 15mm, the powder feeding amount is 0.8-1g / min, the overlap amount is 1-1.2mm, the spot diameter is 2.2-2.4mm, the powder feeder flow rate is 5L / min, the protective gas is Ar gas, the protective gas flow rate is 20-25L / min, and the substrate does not need to be preheated.

[0022] In one embodiment of the present invention, in step S3, selecting corresponding laser cladding parameters according to the defect type includes:

[0023] When the defect type is corner defect and edge defect, the laser power is 2000-2200W, the laser scanning speed is 10-12mm / s, the defocus amount is 15mm, the powder feeding amount is 0.7-0.8g / min, the overlap amount is 0.8-1mm, the spot diameter is 1.6-1.8mm, the powder feeder flow rate is 5L / min, the protective gas is Ar gas, the protective gas flow rate is 20-25L / min, the substrate does not need to be preheated, and the laser head is tilted 30°.

[0024] In one embodiment of the present invention, in step S4, after the repair is completed, the excess cladding material is removed, and a repair surface matching the base material of the substrate is obtained by grinding, including:

[0025] When the defect type is a surface defect, milling is used to remove most of the excess, and then the repair surface is polished and smoothed with an oilstone.

[0026] In one embodiment of the present invention, in step S4, after the repair is completed, the excess cladding material is removed, and a repair surface matching the base material of the substrate is obtained by grinding, including:

[0027] When the defect type is corner defect or edge defect, use electric polishing disc and 70-90 mesh sandpaper to grind the repair surface smooth.

[0028] The above technical solution of the present invention has the following advantages compared with the prior art:

[0029] The present invention discloses a laser repair method for a 6061 aluminum alloy substrate with low oxygen conductivity and color difference. By adding Sc and Zr elements as composite modifiers, the weld performance is enhanced, the common softening problem in laser repair is effectively solved, the bonding strength between the repair layer and the substrate is improved, and the long-term performance of the chassis repair part under high vibration conditions is ensured. The color difference between the substrate and the repair layer of the repair powder of the present invention is much lower than the color difference of the traditional AlSi10Mg powder, which meets the strict requirements of aviation chassis for appearance consistency.

[0030] The tensile strength after repair and the ratio of the tensile strength of the weld to the tensile strength of the base material meet the high strength requirements of the aviation chassis. The color difference between the repaired substrate and the repair layer does not exceed 1.6 on average, and the ratio of the tensile strength to the base material strength reaches more than 80%.

[0031] The present invention optimizes the cladding process parameters (powder feeding, laser power, scanning speed, etc.) to obtain a smaller cladding layer thickness, reduce hydrogen precipitation, and significantly reduce porosity, thereby ensuring the density and uniformity of the cladding layer. It is suitable for a variety of complex repair shapes (such as surface defects, corner defects and edge defects), the repaired part has a precise geometric shape, can be quickly formed, and reduces the workload of subsequent processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings.

[0033] Figure 1 It is a flow chart of the laser repair method of the 6061 aluminum alloy substrate with low oxygen conductivity and chromatic aberration of the present invention.

[0034] Figure 2 It is a schematic diagram of the morphology of the planar defect in Example 1 of the present invention.

[0035] Figure 3 It is a schematic diagram of the morphology after the planar defect is repaired in Example 1 of the present invention.

[0036] Figure 4 It is a schematic diagram of the morphology of the surface defect after polishing in Example 1 of the present invention.

[0037] Figure 5 It is a schematic diagram of the morphology after the edge defect is repaired in Example 2 of the present invention (not polished).

[0038] Figure 6 It is a schematic diagram of the morphology after the edge defect is repaired in Example 2 of the present invention (after polishing).

[0039] Figure 7It is a schematic diagram of the morphology after the corner defect is repaired in Example 2 of the present invention (not polished).

[0040] Figure 8 It is a schematic diagram of the morphology after the corner defect is repaired in Example 2 of the present invention (after polishing).

[0041] Fig. 9 It is a three-dimensional image of the U-groove repair specimen in Example 3 of the present invention.

[0042] Fig.10 This is a schematic diagram of the repair route in Example 3 of the present invention.

[0043] Fig.11 3 is a schematic diagram of color difference comparison in Example 3 of the present invention. DETAILED DESCRIPTION

[0044] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0045] In the present invention, "several" means one or more, "multiple" means more than two, "greater than", "less than", "exceed" and the like are understood to exclude the number itself; "above", "below", "within" and the like are understood to include the number itself. In the description of the present invention, if there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0046] Example 1

[0047] Reference Figure 1 This embodiment provides a laser repair method for a 6061 aluminum alloy substrate with low oxygen conductivity and color difference for the surface defects of the 6061 aluminum alloy aviation chassis. Figure 2 The morphology of the surface defect is shown as an example. It is rectangular and the damaged size is 21.5mm×6.9mm×0.3mm. The repair method includes:

[0048] S1. Provide repair powder, which is composed of the following components (wt.%, weight percent): Si: 0.4-0.8wt.%, Mg: 0.8-1.6wt.%, Cu: 0.15-0.4wt.%, Sc: 0.2-0.3wt.%, Zr: 0.08-0.14wt.%, impurity content is less than 1%, and the balance is Al; the powder particle size range of the repair powder is 50-150μm. Place the repair powder in a vacuum drying oven and dry it at 80-120℃ for 0.8-1.2h, and add it to the powder feeder after cooling.

[0049] S2. Surface treatment is performed on the surface defects of the substrate of 6061 aluminum alloy to form a flat defective surface (with a certain degree of roughness); specifically, the notch is polished with an electric file and an electric wire brush to remove the surface oxide layer, ensure a smooth and flat surface, and control the chamfers on all sides to be 100°-140°.

[0050] S3. Select laser cladding parameters, laser power of 1400-1600W, laser scanning speed of 8-12mm / s, defocus of 15mm, powder feeding of 0.8-1g / min, overlap of 1-1.2mm, spot diameter of 2.2-2.4mm, powder feeder flow of 5L / min, shielding gas of Ar gas, shielding gas flow of 20-25L / min, substrate does not need to be preheated, use powder feeder to deliver the repair powder to the defective surface, perform laser cladding repair, after each layer of repair is completed, use electric file and electric wire brush to clean the oxide on the cladding surface, adjust the laser defocus, and perform the next layer of cladding operation until the repair is completed. Reference Figure 3 shown.

[0051] It can be understood that the laser power: 1400~1600W provides moderate energy input to clad the repair powder and substrate surface; the laser scanning speed: 8~12mm / s controls the scanning efficiency and smoothness of the repair process; the defocus: 15mm optimizes the distance between the laser focus and the workpiece surface to achieve stable cladding; the powder feeding amount: 0.8~1g / min ensures the stability of the powder supply and avoids excessive thickness of the cladding layer; the overlap: 1~1.2mm adjusts the overlapping area between the cladding layers to ensure surface flatness and continuity; the spot diameter: 2.2~2.4mm is suitable for uniform cladding of larger areas; the powder feeder flow: 5L / min maintains a stable powder feeding airflow to ensure uniform powder transmission; argon is used with a flow rate of 20~25L / min to prevent oxidation of the cladding area and ensure the quality of the weld; the workpiece does not need to be preheated, which effectively reduces the risk of thermal deformation.

[0052] S4. After the repair is completed, use milling to remove most of the excess, and then use an oilstone to grind the repaired surface smooth. Figure 4 shown.

[0053] Sc and Zr elements are used as composite modifiers to strengthen the weld performance and solve the common softening problem in the laser repair process of aluminum alloy. The laser process parameters are adjusted based on the powder, and a smaller powder feeding amount is used to obtain a smaller cladding layer thickness, which is conducive to the precipitation of hydrogen during the cladding process, reduces the porosity and obtains a higher cladding quality. This repair process can obtain excellent cladding layer quality, good molding after laser cladding repair, good mechanical properties, and small color difference with the parent material matrix after oxygen conduction, meeting the appearance requirements for the chassis.

[0054] Vibration tests were carried out on the repaired specimens to verify the test. Vertical durable vibration was carried out at 1.6 times the functional vibration in the project. The vibration time was 6 hours. No shock absorber was installed on the chassis during vibration. No cracking or falling off was found after vibration.

[0055] Example 2

[0056] Reference Figure 1 , Figures 5 to 8 As shown, this embodiment provides a laser repair method for a 6061 aluminum alloy substrate with low oxygen conductivity and chromatic aberration for corner defects and edge defects of an aviation chassis made of 6061 aluminum alloy, comprising:

[0057] S1. Provide repair powder, which is composed of the following components: Si: 0.4-0.8wt.%, Mg: 0.8-1.6wt.%, Cu: 0.15-0.4wt.%, Sc: 0.2-0.3wt.%, Zr: 0.08-0.14wt.%, impurity content is less than 1%, and the balance is Al; the powder particle size range of the repair powder is 50-150μm. Place the repair powder in a vacuum drying oven and dry it at 80-120℃ for 0.8-1.2h, and add it to the powder feeder after cooling.

[0058] S2. Surface treatment is performed on the corner defects and edge defects of the 6061 aluminum alloy substrate to form a flat defect surface (with a certain degree of roughness); specifically, the notch is polished with a file to remove the surface oxide layer, and the notch is polished into a flat inclined surface.

[0059] S3. Select laser cladding parameters: laser power of 2000-2200W, laser scanning speed of 10-12mm / s, defocus of 15mm, powder feeding of 0.7-0.8g / min, overlap of 0.8-1mm, spot diameter of 1.6-1.8mm, powder feeder flow of 5L / min, shielding gas of Ar gas, shielding gas flow of 20-25L / min, substrate preheating is not required, laser head is tilted 30°, and the repair powder is delivered to the defective surface by powder feeder for laser cladding repair. After each layer of repair is completed, use electric file and electric wire brush to clean the oxide on the cladding surface, adjust the defocus of the laser, and carry out the next layer of cladding operation until the repair is completed.

[0060] It can be understood that the laser power: 2000~2200W, providing higher energy density to meet the cladding needs of local complex structures; laser scanning speed: 10~12mm / s, controlling energy distribution to reduce the impact of overheating; defocus: 15mm, maintaining a stable focus in the cladding area; powder feeding amount: 0.7~0.8g / min, suitable for smaller repair areas to prevent accumulation of cladding layers; overlap: 0.8~1mm, adapting to uniform repair of local complex shapes; spot diameter: 1.6~1.8mm, suitable for precise repair of small areas; powder feeder flow: 5L / min, maintaining uniform powder delivery; protective gas: argon flow 20~25L / min, avoiding oxidation of the cladding layer; the laser head is tilted 30° to facilitate the laser entry in the corner area to ensure the bonding quality of the cladding layer and the substrate; the workpiece does not need to be preheated to reduce the potential deformation risk caused by heat input.

[0061] S4. After the repair is completed, use an electric polishing disc and 70-90 grit sandpaper to smooth the repaired surface.

[0062] Sc and Zr elements are used as composite modifiers to strengthen the weld performance and solve the common softening problem in the laser repair process of aluminum alloy. The laser process parameters are adjusted based on the powder, and a smaller powder feeding amount is used to obtain a smaller cladding layer thickness, which is conducive to the precipitation of hydrogen during the cladding process, reduces the porosity and obtains a higher cladding quality. This repair process can obtain excellent cladding layer quality, good molding after laser cladding repair, good mechanical properties, and small color difference with the parent material matrix after oxygen conduction, meeting the appearance requirements for the chassis.

[0063] Vibration tests were carried out on the repaired specimens to verify the test. Vertical durable vibration was carried out at 1.6 times the functional vibration in the project. The vibration time was 6 hours. No shock absorber was installed on the chassis during vibration. No cracking or falling off was found after vibration.

[0064] Example 3

[0065] Reference Fig. 9As shown, in this embodiment, the U-shaped groove repair sample of the 6061-T6 aluminum alloy substrate is repaired using different powders (AlSi10Mg and the powder in Example 1 or 2), referring to Fig.10 As shown, the repair process (route) is unidirectional, from left to right, from bottom to top; the laser cladding parameters are: laser power is 1400-1600W, laser scanning speed is 8-12mm / s, defocus is 15mm, powder feeding is 0.8-1g / min, overlap is 1-1.2mm, spot diameter is 2.2-2.4mm, powder feeder flow is 5L / min, shielding gas is Ar gas, and shielding gas flow is 20-25L / min. The rest of the process is the same as in Example 1.

[0066] The tensile strength of the samples repaired with different powders is shown in Table 1. It can be seen that the tensile strength after repair with the powder of the present invention is 231MPa, and the tensile strength of the weld reaches 80% of the strength of the parent material, which is close to the method of using AlSi10Mg as the repair powder (83%), meeting the high strength requirements of the aviation chassis. The reliability of the repair layer under high-frequency vibration conditions was verified in the vibration test, and no cracking or falling off occurred, proving that the repaired part has excellent fatigue performance and structural stability.

[0067] Table 1: Tensile strength of samples repaired with different powders

[0068]

[0069] The color difference between the base material and the repair layer was measured using a colorimeter, and the results are shown in Table 2. Referring to the evaluation of the degree and grade of color difference in GB / T1766 (Table 3), the use of the powder of the present invention for repair can achieve very slight color change, meeting the color difference requirements.

[0070] Therefore, when the repair powder of the present invention is used, the color difference between the substrate and the repair layer is 1.58 on average, which is much lower than the color difference of 22.96 of the traditional AlSi10Mg powder, thus meeting the strict requirements of aviation chassis for appearance consistency, especially for areas that do not require spraying. Fig.11 The color difference comparison between the two objects is shown (the left one is the restoration method of the present invention). It can be seen that based on the GB / T1766 standard, the restoration method can achieve "very slight color change", which is significantly better than the traditional method.

[0071] Table 2: Color difference between different powder bases and repair layers

[0072]

[0073] Table 3: Discoloration degree and discoloration grade

[0074] grade <![CDATA[Color difference / ΔE * > Discoloration degree 0 ≤1.5 No discoloration 1 1.6～3.0 Very slight discoloration 2 3.1～6.0 Slight discoloration 3 6.1～9.0 Obvious discoloration 4 9.1～12.0 Larger discoloration 5 ＞12.0 Severe discoloration

[0075] In summary, the repair powder of the present invention takes into account both the mechanical performance requirements (high strength, high hardness) and the appearance requirements (low oxygen conductivity color difference) by optimizing the component ratio. Compared with traditional high-silicon powders (such as AlSi10Mg), the color difference of this powder is extremely low after oxygen conduction, which meets the strict requirements of aviation chassis for appearance consistency. At the same time, the repair layer has high bonding strength with the substrate and stable performance.

[0076] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A laser repair method for a 6061 aluminum alloy substrate with low oxygen conductivity and chromatic aberration, characterized in that: include: S1. Provide repair powder, the repair powder consists of the following components Composition: Si: 0.4~0.8wt.%, Mg: 0.8~1.6wt.%, Cu: 0.15~0.4 wt.%, Sc: 0.2~0.3 wt.%, Zr: 0.08~0.14 wt.%, impurity content is less than 1%, the balance is Al; S2. Surface treatment is performed on defective parts of the substrate of the 6061 aluminum alloy to form a smooth defective surface; S3, selecting laser cladding parameters according to the defect type, using a powder feeder to deliver the repair powder to the defect surface, performing laser cladding repair, cleaning the oxide on the cladding surface after each layer of repair is completed, and adjusting the laser defocusing amount to perform the next layer of cladding operation until the repair is completed; S4. After the repair is completed, remove the excess cladding material and obtain a repair surface that matches the base material of the substrate through grinding.

2. The laser repair method for a 6061 aluminum alloy substrate with low oxygen conductivity and chromatic aberration according to claim 1 is characterized in that: The morphology of the defective parts of the substrate includes surface defects, edge defects and corner defects.

3. The laser repair method for a 6061 aluminum alloy substrate with low oxygen conductivity and chromatic aberration according to claim 1 is characterized in that: In step S1, the repair powder has a particle size range of 50-150 μm.

4. The laser repair method for a 6061 aluminum alloy substrate with low oxygen conductivity and chromatic aberration according to claim 1 is characterized in that: In step S2, surface treatment is performed on the defective parts of the substrate of the 6061 aluminum alloy to form a flat defective surface, including: When the defect type is a surface defect, use an electric file and an electric wire brush to grind the notch to remove the surface oxide layer, ensure the surface is smooth and flat, and control the chamfers around 100°-140°.

5. The laser repair method for a 6061 aluminum alloy substrate with low oxygen conductivity and chromatic aberration according to claim 1 is characterized in that: In step S2, surface treatment is performed on the defective parts of the substrate of the 6061 aluminum alloy to form a flat defective surface, including: When the defect type is an angle defect or an edge defect, use a file to grind the notch to remove the surface oxide layer and grind the notch into a smooth bevel.

6. The laser repair method for a 6061 aluminum alloy substrate with low oxygen conductivity and chromatic aberration according to claim 1 is characterized in that: In step S3, before the repairing powder is uniformly delivered to the defective surface by a powder feeder, the method further includes: The repair powder is placed in a vacuum drying oven and dried at 80-120° C. for 0.8-1.2 h, and added to a powder feeder after cooling.

7. The laser repair method for a 6061 aluminum alloy substrate with low oxygen conductivity and chromatic aberration according to claim 1 is characterized in that: In step S3, corresponding laser cladding parameters are selected according to the defect type, including: When the defect type is a planar defect, the laser power is 1400~1600W, the laser scanning speed is 8~12mm / s, the defocus amount is 15mm, the powder feeding amount is 0.8~1g / min, the overlap amount is 1~1.2mm, the spot diameter is 2.2~2.4mm, the powder feeder flow rate is 5L / min, the protective gas is Ar gas, the protective gas flow rate is 20~25L / min, and the substrate does not need to be preheated.

8. The laser repair method for a 6061 aluminum alloy substrate with low oxygen conductivity and chromatic aberration according to claim 1 is characterized in that: In step S3, corresponding laser cladding parameters are selected according to the defect type, including: When the defect type is corner defect and edge defect, the laser power is 2000~2200W, the laser scanning speed is 10~12mm / s, the defocus amount is 15mm, the powder feeding amount is 0.7~0.8g / min, the overlap amount is 0.8~1mm, the spot diameter is 1.6~1.8mm, the powder feeder flow rate is 5L / min, the protective gas is Ar gas, the protective gas flow rate is 20~25L / min, the substrate does not need to be preheated, and the laser head is tilted 30°.

9. The laser repair method for a 6061 aluminum alloy substrate with low oxygen conductivity and chromatic aberration according to claim 1, characterized in that: In step S4, after the repair is completed, the excess cladding material is removed, and a repair surface matching the base material of the substrate is obtained by grinding, including: When the defect type is a surface defect, milling is used to remove most of the excess, and then the repair surface is polished and smoothed with an oilstone.

10. The laser repair method for a 6061 aluminum alloy substrate with low oxygen conductivity and chromatic aberration according to claim 1, characterized in that: In step S4, after the repair is completed, the excess cladding material is removed, and a repair surface matching the base material of the substrate is obtained by grinding, including: When the defect type is corner defect or edge defect, use electric polishing disc and 70-90 mesh sandpaper to grind the repair surface smooth.

Images