CN114505493A

CN114505493A - Method for repairing 7-series aluminum alloy through small-spot laser additive under atmosphere protection condition

Info

Publication number: CN114505493A
Application number: CN202210112886.3A
Authority: CN
Inventors: 折洁; 祝弘滨; 任欣; 王行涛; 李明高; 刘昱; 赵明元; 龚明
Original assignee: CRRC Academy Co Ltd
Current assignee: CRRC Industry Institute Co Ltd
Priority date: 2022-01-29
Filing date: 2022-01-29
Publication date: 2022-05-17
Anticipated expiration: 2042-01-29
Also published as: CN114505493B

Abstract

The invention relates to the technical field of aluminum alloy material additive repair, in particular to a method for repairing 7-series aluminum alloy by using small-spot laser additive under the atmosphere protection condition. The invention provides a laser additive repair method of a 7-series aluminum alloy, which is characterized in that special powder of an aluminum-magnesium-scandium-zirconium-aluminum alloy is used as a repair material, and a small light spot mode is adopted for repair under an inert atmosphere and a small light spot mode is adopted for repair. By controlling the technological parameters such as laser power, powder feeding amount, scanning speed, powder carrying gas flow and the like, the interface of a repair area and a base material area is completely metallurgically combined, the quality is good, no obvious defects such as air holes, cracks and the like exist in the repair area, the density of the repair area is more than or equal to 99.9 percent, the room-temperature tensile property of a laser repair sample can reach more than 100 percent of the mechanical property of a base material, and the problems of air holes, cracks and the like which are common in the process of laser repair of aluminum alloy are solved to a great extent.

Description

Method for repairing 7-series aluminum alloy through small-spot laser additive under atmosphere protection condition

Technical Field

The invention belongs to the technical field of additive repair of aluminum alloy materials, and particularly relates to a method for repairing 7-series aluminum alloy by using small-spot laser additive under the atmosphere protection condition.

Background

Aluminum alloys are distinguished from numerous materials due to excellent properties such as light weight, excellent formability, high strength, good plasticity, impact resistance, corrosion resistance, good sealing performance, high recycling rate and the like, and are very popular in the industrial fields such as aerospace, rail transit and the like. Particularly in the manufacture of rail transit equipment, the aluminizing rate is continuously improved, and the method is the most effective method for realizing the large-size widening of the section bar and reducing the self weight of the vehicle body.

However, along with the increase of the speed and the service life of the train, the damage (such as fatigue crack, abrasion, erosion and the like) of the aluminum alloy train body parts can cause the parts to fail and even be scrapped. Under complicated working conditions, the aluminum alloy member is cracked to different degrees due to long-term operation, so that the cracking phenomenon is sometimes generated and unpredictability is not realized, and great hidden danger is caused to the life safety of people.

Aiming at the damaged parts of the aluminum alloy, the problem is mainly solved by adopting a new part replacement or welding repair technology at present. The direct abandonment or the damaged spare part of change will lead to the fact very big waste and cost expenditure, actually mostly adopt the welding repair means to solve preferentially.

At present, the main repairing methods for the damage of the aluminum alloy component of the rail transit train are many, such as welding, cladding, thermal spraying, brush plating and the like, and the repairing technologies are already applied to the repair of parts, but certain defects still exist.

For example, the repair layer obtained by the brush plating and thermal spraying technology is very thin (less than or equal to 0.3mm), is poorly combined with the substrate, is only suitable for surface repair, and cannot repair the damaged part of the shape; the fusion welding technology has large heat input and insufficient energy concentration, so that a heat affected zone of a repaired base body is large, the dilution rate is high, the performance of the repaired base body is reduced, and parts are easy to deform and even crack; the repair area obtained by brazing has large performance difference with the matrix, and the bonding with the matrix is relatively weak by welding, so that the repair area is not suitable for large-volume repair.

Therefore, the traditional repairing and remanufacturing technology has the defects of narrow application range, reduced performance of a repaired substrate, complex process, long production period, large heat input, weak combination with the substrate, thin repairing layer and the like, so that the existing achievement is difficult to meet the actual engineering application requirement.

Therefore, the repair problem of the aluminum alloy parts for the rail transit is a common key technical problem which needs to be solved urgently in the current stage of aluminum alloy welding, a new repair technology needs to be researched, and how to prolong the service life of the key structure of the rail transit vehicle is further explored.

The laser additive repair technology has the characteristics of high energy density, high cooling speed, low dilution rate of a cladding layer, extremely fine beam current, high machining precision, wide range of machinable materials, repair of complex shapes and the like, has great development potential in the technical field of remanufacturing, and is widely used for repairing aluminum alloy parts in recent years.

The laser repair of 7-series high-strength aluminum alloys has been studied in large numbers. In the previous research, the Al-Si powder is mostly adopted to repair the 7 series aluminum alloy, because the temperature range between the solid phase and the liquid phase of the Al-Si alloy is narrow, the dendritic crystal gap is small at a high cooling speed in the solidification process, the backfilling is easy, cracks are not easy to generate, the powder has good flowability, and the formability is excellent. However, since Al-Si alloys have lower strength than 7-series aluminum alloys, when the 7-series aluminum alloy substrates are repaired in a large area using these alloys, the mechanical properties of the entire parts are deteriorated.

The special aluminum-magnesium-scandium-zirconium-aluminum alloy powder is special high-strength aluminum alloy powder for additive manufacturing developed in two years, and can be used for printing a product with high strength and good fatigue performance. The powder laser additive repair of 7-series aluminum alloy has great guiding significance in improving the overall strength of a finished piece. However, the air hole defect in the process of repairing by adopting the special powder for the aluminum-magnesium-scandium-zirconium-aluminum alloy is still a problem which is difficult to eliminate, and the mechanical property and the fatigue resistance of the repaired copy piece are influenced to a certain extent.

Disclosure of Invention

The invention provides a process method for repairing 7-series aluminum alloy by adopting small-facula mode laser additive under the protection condition of inert atmosphere, aiming at the problems of air hole and crack defects in the process of repairing 7-series aluminum alloy by using special powder laser additive of aluminum-magnesium-scandium-zirconium-aluminum alloy.

The invention provides a laser additive repair method of a 7-series aluminum alloy, which is characterized in that special powder of an aluminum-magnesium-scandium-zirconium-aluminum alloy is used as a repair material, and a small light spot mode is adopted for repair in an inert atmosphere.

The research of the invention finds that the heat affected zone formed under the condition of small light spots is small, the damage to the base material is small, and the defects of air holes, cracks and the like are reduced.

Further, the process parameters of the small spot mode are as follows: the diameter of a light spot is 1-3 mm, the laser repair power is 1000-1700W, the scanning speed is 380-680 mm/min, the powder gas flow is 2-8L/min, argon is introduced into the atmosphere protection cabin, and the oxygen content is kept to be less than or equal to 100 ppm.

According to the invention, by controlling the technological parameters such as laser power, powder feeding amount, scanning speed, powder carrying gas flow and the like, the interface of the repair area and the base material area is completely metallurgically bonded, the quality is good, no defects such as obvious pores, cracks and the like exist in the repair area, the density of the repair area is more than or equal to 99.9%, the room-temperature tensile property of a laser repair sample can reach 75% or more of the mechanical property of the base material, and the problems of pores, cracks and the like which are common in the process of laser repair of aluminum alloy are solved to a great extent.

When the aluminum alloy forging is subjected to laser material increase repair, a V-shaped groove is usually prefabricated, and the depth of the V-shaped groove covers the depth of a damaged part of the aluminum alloy. In the repairing process, the aluminum alloy material at the position of the V-shaped groove with a small angle reflects light seriously and has low laser absorption rate.

In order to ensure that the metallurgical quality of the interface of the aluminum alloy matrix and the repair area is good and metallurgical defects such as unfused fusion do not occur at the interface joint, the prefabricated V-shaped groove of the aluminum alloy base material is pretreated by adopting a groove inclination bottoming method before the small-spot mode laser repair is implemented.

The research of the invention finds that the groove slope priming method is adopted to pre-repair the V-shaped groove, so that the phenomenon that the angle between a laser head and the groove is smaller to reflect light to the opposite groove when the repair angle is smaller, the metallurgical quality of the groove can be improved to a certain extent, and the metallurgical bonding strength of a matrix area and a repair interface is enhanced.

Preferably, in the pretreatment, the light emitting direction of the laser is controlled to be perpendicular to the inclined plane of the V-groove. In this state, laser material increase is carried out on one surface of the V-shaped groove, and the process is similar to the process of material increase of aluminum alloy powder on a plane, so that the defects of light reflection, insufficient energy and the like caused by laser repair angles can be reduced, and the absorption of the laser energy on the surface of the aluminum alloy is improved.

As one of the specific operation modes of the present invention, the inclination angle of the "groove inclination priming method" is 0.2 to 0.6 times the angle of the V-groove. The number of layers of the priming pre-repairing treatment is 1-2. And after finishing the priming pre-repairing treatment, aligning the aluminum alloy base material with the V-shaped groove, and continuously performing planar laser additive repairing by adopting a small light spot mode. In the invention, the angle of the V-shaped groove is 90-120 degrees, and the depth is 1-8 mm.

In the invention, the special aluminum-magnesium-scandium-zirconium-aluminum alloy powder comprises the following chemical components: cr is less than 0.01 percent, Fe is 0.05-0.2 percent, Mg7.0-12.0 percent, Mn0.4-0.6 percent, Ni is less than 0.01 percent, Sc0.15-0.6 percent, Si is 0.5-0.7 percent, Ti is less than 0.04 percent, Zr is 0.12-0.4 percent, O is less than 0.005 percent, N is less than 0.005 percent, H is less than 0.001 percent, and the balance is aluminum.

The method for repairing the aluminum alloy by the small-spot laser additive is suitable for 7-series aluminum alloys such as 7B05, 7003, 7020, 7050 and the like.

Compared with the prior art, the invention has the following advantages:

1. according to the invention, the small light spot mode is adopted for laser material increase repair of the 7-series aluminum alloy, and the heat affected zone formed under the small light spot condition is small, so that the damage to the base material is small, and the defects of air holes, cracks and the like can be effectively reduced; on the basis, the interface of the repair area and the base material area is completely metallurgically combined by reasonably controlling the technological parameters such as laser power, powder feeding amount, scanning speed, powder carrying gas flow and the like, the quality is good, no defects such as obvious pores, cracks and the like exist in the repair area, the density of the repair area is more than or equal to 99.9 percent, the room-temperature tensile property of a laser repair sample can reach 75 percent or more of the mechanical property of the base material, and the problems of pores, cracks and the like which are common in the process of repairing the aluminum alloy by laser are solved to a great extent.

2. The invention adopts a groove priming method to pre-repair the V-shaped groove, and the method can overcome the phenomenon that when the V-shaped groove with a smaller repairing angle is repaired, the angle between a laser head and the groove is smaller and the light is reflected to the opposite groove, thereby improving the metallurgical quality of the groove to a certain extent and strengthening the metallurgical bonding strength of a matrix area and a repairing interface.

3. By controlling the light emitting direction of the laser to be vertical to the inclined plane of the V-shaped groove, the process of laser material increase of the inclined plane of the groove is similar to the process of material increase of aluminum alloy powder on a plane, so that the defects of light reflection, insufficient energy and the like caused by laser repair angles can be reduced, and the absorption of the laser energy on the surface of the aluminum alloy is improved.

Drawings

FIG. 1 shows the microstructure of a repair part obtained by a groove priming method.

FIG. 2 is a microstructure of a restoration obtained by a conventional restoration method in comparative example 1.

FIG. 3 is a microstructure of the prosthesis repaired in comparative example 2.

FIG. 4 is a microstructure of the prosthesis repaired in comparative example 3.

Fig. 5 is a trend of micro-hardness evolution of laser additive repair 7B05 aluminum alloy.

FIG. 6 shows the sampling positions and numbers of the samples in the mechanical property test.

Detailed Description

The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

As one embodiment of the present invention, the method for laser additive repair of a 7-series aluminum alloy includes the following steps:

the method comprises the following steps: a7-series aluminum alloy is used as a repair base material, a V-shaped groove is machined on the base material in a linear cutting mode, a machining mode and the like, the angle of the groove is 90-120 degrees, and the depth is 1-8 mm (the depth can cover most of the damage depth of the existing aluminum alloy).

Step two: and polishing the area to be repaired, removing the surface oxide layer, and cleaning the surface of the base material by using alcohol or acetone so as to improve the absorption of the laser energy on the surface of the aluminum alloy.

And after cleaning, drying the base material and the special repair material. Putting the base material into a vacuum heating furnace, setting the heating temperature to be 90-130 +/-10 ℃, and keeping the temperature for 100 +/-10 min so as to ensure that no residual liquid exists at the part cleaned by alcohol or acetone. Meanwhile, the special aluminum-magnesium-scandium-zirconium-aluminum alloy powder for laser repair is placed into a vacuum heating furnace, the heating temperature is set to be 120-fold-160 ℃, and the temperature is kept for 100-fold-130 min +/-10 min so as to remove residual water vapor in the powder.

Step three: and (3) adopting small-spot laser additive repair, and setting laser repair process parameters. The method comprises the steps of adopting powder feeding type laser repair equipment, setting laser repair power to be 1000W-1700W, setting the diameter of a light spot to be 1-3 mm, setting scanning speed to be 380-680 mm/min, setting the flow of powder gas to be 2-8L/min, introducing argon gas into an atmosphere protection cabin, and keeping the oxygen content to be less than or equal to 100 ppm. And maintaining the part in an inert atmosphere in the repairing process, and repairing the part in a small light spot mode.

Step four: adopts a groove inclined bottoming method. In the repairing process, for a V-shaped groove with a smaller angle, the aluminum alloy material at the position reflects light seriously, the laser absorption rate is lower, and in order to ensure that the metallurgical quality of the interface of an aluminum alloy substrate and a repairing area is good and the metallurgical defects of non-fusion and the like do not occur at the interface joint, the invention provides that before the laser repairing of the V-shaped groove, the aluminum alloy substrate with the V-shaped groove is obliquely placed at a certain angle, and the placed angle is equal to 0.2-0.6 times of the angle of the groove.

The concrete expression is that the inclined plane of the V-shaped groove which originally forms a certain angle with the laser light-emitting direction is firstly horizontally placed on a workbench, even if the laser light-emitting direction is vertical to the inclined plane of the V-shaped groove. In this state, laser material increase is carried out on one surface of the V-shaped groove, the process is similar to the process of adding aluminum alloy powder on a plane, the defects of light reflection, insufficient energy and the like caused by laser repair angles can be reduced, and the absorption of the aluminum alloy surface to laser energy is improved.

After the first inclined plane is machined (1-2 layers are machined in the same way), the steps are repeated, and the other inclined plane is reversed to continue to form the groove from 1-2 layers to the bottom.

Step five: and step four, after 1-2 layers of the V-shaped groove are bottomed, the groove is aligned, and the NC program is continuously used for carrying out plane restoration on the V-shaped groove. Until the groove is repaired.

Example 1

The embodiment provides a method for repairing a 7-series high-strength aluminum alloy plate by using Al-Mg-Sc-Zr high-strength aluminum alloy powder as a repairing material and adopting a laser additive repair technology. And the whole repairing process uses small light spots and atmosphere protection, and the aluminum alloy prefabricated groove is repaired.

The method comprises the following specific steps:

(1) A7B 05 aluminum alloy plate is selected as a base material, and the specific composition of the base material is shown in Table 1. A V-shaped groove is machined on a base material in a linear cutting mode, a machining mode and the like, the angle of the groove is 90-120 degrees, and the depth is 1-8 mm (the depth can cover most of the damage depth of the existing aluminum alloy).

The cladding material is aluminum magnesium scandium zirconium aluminum alloy spherical powder, and the particle diameter is 50-120 mu m;

the components of the aluminum-magnesium-scandium-zirconium-aluminum alloy are shown in table 1, and the powder feeding particle range is 200-400 m mesh.

TABLE 1.7B05 and Al-Mg-Sc-Zr-Al alloy chemical compositions

Material

Cr

Fe

Mg

Mn

Ni

Sc

Si

7B05 aluminum alloy

0.18

0.16

1.14

0.33

＜0.01

0.047

Aluminum magnesium scandium zirconium

＜0.01

0.053

8.63

0.50

＜0.01

0.50

0.53

Material

Ti

Zr

O

N

H

Zn

7B05 aluminum alloy

0.040

0.14

0.020

＜0.005

＜0.001

4.59

Aluminum magnesium scandium zirconium

0.013

0.33

＜0.005

＜0.001

-

(2) In order to improve the absorption of the surface of the aluminum alloy to laser energy, the surface of a sample is polished to remove an oxide film before laser repair.

(3) Setting small-spot laser repair process parameters

Repairing process parameters are as follows: the method comprises the steps of adopting powder feeding type laser repair equipment, setting laser repair power to be 1000W-1700W, setting the diameter of a light spot to be 1-3 mm, setting scanning speed to be 400-600 mm/min, setting the flow of powder gas to be 2-5L/min, introducing argon gas into an atmosphere protection cabin, and keeping the oxygen content to be less than or equal to 100 ppm. And maintaining the part in an inert atmosphere in the repairing process, and repairing the part in a small light spot mode.

(4) In the repairing process, because the aluminum alloy has low laser absorption rate and relatively serious light reflection, in order to ensure that the metallurgical quality of the interface between the aluminum alloy matrix and the repairing area is good and metallurgical defects such as unfused and the like do not occur at the interface joint, before repairing the V-shaped groove, the aluminum alloy substrate with the V-shaped groove is obliquely placed at a certain angle, and the placed angle is equal to 1/2 of the angle of the groove.

The concrete expression is that the inclined plane of the V-shaped groove which originally forms a certain angle with the laser light-emitting direction is firstly horizontally placed on a workbench, and the laser light-emitting direction and the inclined plane of the V-shaped groove are in a vertical state in real time. In this state, the laser material increase is carried out on one surface of the V-shaped groove, the process is similar to the material increase of aluminum alloy powder on a plane, and the defects of light reflection, insufficient energy and the like caused by the laser repair angle can be reduced.

And after the first inclined plane is machined (1-2 layers are machined in the same way), repeating the steps, and reversing the other inclined plane to continue forming the 1-2 layers of the groove.

(5) And returning the groove to be normal, and continuously using an NC program to carry out plane restoration on the V-shaped groove. Until the groove is repaired.

Effect verification

1. Microstructure:

comparative example 1

The aluminum alloy matrix obtained by the conventional repairing method is taken as a reference example. The conventional repairing method is a method for directly repairing the V-shaped groove in a common environment (air atmosphere and large light spot) without priming the V-shaped groove.

Comparing fig. 1 and fig. 2, it can be seen that after the sample is repaired by the groove slope priming method, the metallurgical bonding between the base material and the repaired interface is good, and the defects such as cracks and the like do not occur.

Comparative example 2

The comparison example provides a laser additive repair method for 7-series aluminum alloy, which is different from the example 1 in process parameters, wherein the specific repair process parameters are as follows:

adopting powder feeding type laser repair equipment, setting laser repair power at 1900W, setting the diameter of a light spot at 3mm, scanning speed at 800mm/min, introducing argon gas into an atmosphere protection cabin at a powder gas flow of 2-5L/min, and keeping the oxygen content less than or equal to 100 ppm. And maintaining the part in an inert atmosphere in the repairing process, and repairing the part in a small light spot mode.

The same method is adopted for detection, the result is shown in fig. 3, and the problems of pore enlargement, porosity increase, poor repair interface fusion and the like of the repaired aluminum alloy material occur due to mismatching of the process parameter settings, so that the influence of reasonably controlling the matching relationship of each process parameter on the repair effect is illustrated.

Comparative example 3

The comparison example provides a laser additive repair method for 7-series aluminum alloy, and the difference from the example 1 is that a groove inclined priming method is not adopted to carry out pretreatment on a prefabricated V-shaped groove.

The specific repair process parameters are as follows: powder feeding type laser repair equipment is adopted, laser repair power is set to be 1400W, the diameter of a light spot is 1.2mm, scanning speed is 600mm/min, powder gas flow is 2-5L/min, argon gas is introduced into an atmosphere protection cabin, and oxygen content is kept to be less than or equal to 100 ppm. And maintaining the part in an inert atmosphere in the repairing process, and repairing the part in a small light spot mode.

The same method is adopted for detection, the result is shown in fig. 4, and the problems of poor fusion and cracking occur at the repaired aluminum alloy interface joint due to the lack of groove priming auxiliary treatment, so that the influence of the groove inclined priming method on the repairing effect is explained.

2. Microhardness:

FIG. 5 shows the micro-hardness evolution trend of laser repaired 7B05 aluminum alloy, which is to irradiate the substrate area and the repair area respectively by taking the interface as an origin and make a point every 50 μm.

It can be found that the microhardness of the base material area is always kept at about 60Hv, and the microhardness of the heat affected area is basically consistent with that of the base material area because the laser additive repair energy is small and the influence on the change of the microstructure of the heat affected area is small.

After the high-energy laser beam enters the repair area, when the high-energy laser beam scans the matrix, the heat dissipation of the base material is faster, so that the temperature gradient is higher and the cooling speed is faster in the first layers of repair, the tissue stress in the transition area is more concentrated, and the increase of the microhardness is reflected in the hardness value. When the repair is continued along the deposition direction, the heat transfer of the workpiece enters a stable area, and the microhardness gradually tends to be stable and is stabilized at 80 Hv.

3. Mechanical properties

Samples of the repair matrix and the repair area of the aluminum alloy material obtained by the method are cut and tested, and the number of the samples is shown in figure 6.

Additive manufacturing 1-1 represents: sampling the sample with the sampling number of 1-1 by using Ar gas and small-spot laser additive forming;

additive manufacturing 1-2 represents: sampling the sample with the Ar gas and the small-spot laser additive forming number of 1-2;

additive repair 1-1 using the method described in example 1 represents: sampling samples of the Ar gas and small-spot laser additive repair 7B05 aluminum alloy V-shaped groove with the sampling number of 1-1;

additive repair 1-2 using the method described in example 1 represents: sampling samples of the Ar gas and small-spot laser additive repair 7B05 aluminum alloy V-shaped groove with the sampling number of 1-2;

additive repair 2-1 using the method described in example 1 represents: sampling samples of the Ar gas and small-spot laser additive repair 7B05 aluminum alloy V-shaped groove with the sampling number of 2-1;

additive repair 2-2 using the method described in example 1 represents: sampling the sample with the Ar gas and small-spot laser additive repairing 7B05 aluminum alloy V-shaped groove with the sampling number of 2-2;

meanwhile, 7B05 forgings are used as comparative examples, and are compared with additive manufacturing and additive repair.

The test methods of all indexes in the table 2 all adopt the conventional detection method in the industry.

Table 2 mechanical properties of each additive manufacturing sample and additive repairing sample

As can be seen from Table 2:

(1) according to the experimental data of additive manufacturing and 7B05 forgings, the formability is proved to be good by the excellent forming performance of the material under the small light spot Ar gas atmosphere.

(2) According to the additive repair and the test data of the 7B05 forge piece, the tensile strength of the additive repair piece obtained by the method reaches over 100% of the mechanical property of the 7B05 forge piece, the yield strength reaches over 70%, and the elongation reaches 100%.

And observing the fracture area of the additive repair sample, and finding that the fracture positions are all the positions of the forge piece, which shows that the mechanical property of the repair area is superior to that of the forge piece (repair matrix), and shows that the laser repair area and the forge piece matrix have good bonding performance.

In conclusion, the repair piece obtained by repairing the small-spot Ar gas atmosphere by the groove slope priming method is excellent in performance and good in stability.

The above examples show that the small-spot laser additive repair technology under the protection of inert atmosphere is adopted, the method for repairing 7-series aluminum alloy by using aluminum magnesium scandium zirconium aluminum alloy laser additive is feasible, and the bonding force at the repair interface is remarkably enhanced after the repair is carried out by adopting the groove priming method.

Although the invention has been described in detail hereinabove with respect to a general description and specific embodiments thereof, it will be apparent to those skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.

Claims

1. The laser additive repair method of the 7-series aluminum alloy is characterized in that aluminum-magnesium-scandium-zirconium-aluminum alloy powder is used as a repair material, and repair is carried out in a small light spot mode under an inert atmosphere.

2. The laser additive repair method of claim 1, wherein the process conditions of the small spot mode are: the diameter of a light spot is 1-3 mm, the laser repair power is 1000-1700W, the scanning speed is 380-680 mm/min, the powder gas flow is 2-8L/min, argon is introduced into the atmosphere protection cabin, and the oxygen content is kept to be less than or equal to 100 ppm.

3. The laser additive repair method according to claim 2, wherein a prefabricated V-shaped groove of the aluminum alloy base material is pretreated by a groove slope priming method before the small spot mode laser repair is performed.

4. The laser additive repair method according to claim 3, wherein in the pretreatment, the light emitting direction of the laser is controlled to be in a perpendicular relationship with the inclined plane of the V-groove.

5. The laser additive repair method according to claim 4, wherein the inclination angle of the groove inclination priming method is 0.2-0.6 times the angle of the V-groove.

6. The laser additive repair method according to claim 5, wherein the number of layers of the priming pre-repair treatment is 1-2.

7. The laser additive repair method according to claim 6, wherein after the priming pre-repair treatment is completed, the aluminum alloy base material with the V-shaped groove is aligned, and planar laser additive repair is continuously performed in a small spot mode.

8. The laser additive repair method according to claim 7, wherein the angle of the V-shaped groove is 90-120 degrees, and the depth is 1-8 mm.

9. The laser additive repair method according to claim 8, wherein the aluminum magnesium scandium zirconium aluminum alloy special powder comprises the following chemical components:

0.01 percent of Cr, 0.05 to 0.2 percent of Fe, 7.0 to 12.0 percent of Mg, 0.4 to 0.6 percent of Mn, less than 0.01 percent of Ni, 0.15 to 0.6 percent of Sc, 0.5 to 0.7 percent of Si, less than 0.04 percent of Ti, 0.12 to 0.4 percent of Zr, less than 0.005 percent of O, less than 0.005 percent of N, less than 0.001 percent of H and the balance of aluminum.

10. The laser additive repair method of claim 9, wherein the 7-series aluminum alloy is 7B05, 7003, 7020, or 7050.