CN115007863A - Method for repairing internal defects of large aluminum alloy casting - Google Patents
Method for repairing internal defects of large aluminum alloy casting Download PDFInfo
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- CN115007863A CN115007863A CN202210601593.1A CN202210601593A CN115007863A CN 115007863 A CN115007863 A CN 115007863A CN 202210601593 A CN202210601593 A CN 202210601593A CN 115007863 A CN115007863 A CN 115007863A
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/23—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces involving a self-propagating high-temperature synthesis or reaction sintering step
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
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- B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
- B23P6/00—Restoring or reconditioning objects
Abstract
The invention relates to a method for repairing internal defects of a large aluminum alloy casting, which comprises the following steps: s1, carrying out three-dimensional flaw detection on the large aluminum alloy casting, and determining the size and position data of one or more internal defects; s2, preparing a repair channel for communicating the internal defect with the outer surface of the casting; s3, conveying the repairing material to the internal defect by using the repairing channel, and densely filling the internal defect and the repairing channel; the repair material has two forms of solid powder and solid particles; filling the area close to the surface of the casting with solid powder and the area far away from the surface of the casting with a mixture of solid powder and solid particles inside the repair channel; and S4, exciting the reduction exothermic reaction of the repair material by using a linear heat source, melting the repair material, and finally solidifying the repair material into a repaired tissue with mechanical property close to that of the casting body material. The method can solve the problems of high cost, low efficiency, low compactness of materials in the repair area, poor mechanical properties and the like of repairing the internal defects of the aluminum alloy casting.
Description
Technical Field
The invention belongs to the field of defect repair of cast parts, and particularly relates to a repair method for internal defects of large aluminum alloy cast parts.
Background
With the development of large-scale and complicated cast parts in the industries such as automobiles and the like, part scrapping, yield reduction and economic loss caused by casting defects often occur. The defect repair of the casting is an effective method for reducing loss, but the prior art can only repair the surface defect of the casting by repair welding and repair casting, and an effective repair method for the defect in the casting is still lacked.
For example, spanish patent ES2657852T3 discloses a method for repairing internal defects of a nodular cast iron part, comprising: machining the workpiece in the defect area to form a cavity open to the surface of the workpiece; a container having a hole communicating with the chamber is fixed to the workpiece chamber, and molten iron is added to the container to flow into the chamber.
For another example, there is a technique of repairing a defective portion of a part by using a self-propagating reaction; the self-propagating reaction is to induce local chemical reaction by external energy, and after the initial reaction condition is reached, the reaction can be spontaneously carried out without an external heat source. Chinese patent CN201810537505.X discloses a method for repairing an H13 steel pipe die by adopting an SHS metallurgical mode, but the method is only limited to repairing the surface defects of the H13 steel pipe die with a simple structure and cannot adapt to more complex repairing requirements. Chinese patent 201510682347.3 discloses a method for repairing broken and defective bronze relics by using exothermic reaction of self-propagating welding powder, which comprises the steps of obtaining high-temperature molten metal with the same components as the matrix of the bronze relics by using the exothermic reaction of the self-propagating welding powder, solidifying the molten metal into a specific shape in a packaging mold, and forming firm metallurgical bonding with the matrix to realize the repair of the broken and defective bronze relics; the method essentially obtains molten metal by utilizing heat released by self-propagating reaction, and then carries out casting supplementing on the fracture defect part of the bronze ware.
During the technical application process, the following are found: the application of the patent ES2657852T3 and the patent 201510682347.3 to the repair of internal defects of castings has significant disadvantages; because the internal defect of the casting is a closed space, the back pressure in the closed space hinders the smooth inflow of molten metal; enlarging the molten metal flow path can alleviate the above effects, but also increase the corresponding machining allowance and destroy the overall strength and appearance of the casting. On the other hand, no technology is available for actively controlling the phase change behavior of the molten metal in the process of flowing into the internal defects of the casting; the molten metal may solidify before reaching the defect site, resulting in poor repair. For the above reasons, the prior art cannot be applied to internal defects of castings which are deep in position or have a diameter of less than 5 cm.
Disclosure of Invention
In view of the above, the present invention provides a method for repairing internal defects of large aluminum alloy castings, comprising: the mixed material of solid powder and solid particles is used as a repair material to fill the internal defects of the large aluminum alloy casting, and then the repair material is excited to generate self-propagating reaction inside the part; controlling the reaction speed of the self-propagating reaction by changing the specific gravity of solid powder-solid particles in the repair material; the self-propagating reaction causes the repair material to generate a solid-liquid-solid phase change process, and finally forms a compact repair structure which is provided with an internal framework and combined with the casting metallographic phase at the original defect position. The method can solve the problems of high cost and low efficiency of repairing the internal defects of the aluminum alloy casting, low compactness of materials in a repairing area, poor mechanical property and the like.
To achieve the above object of the present invention, the present invention provides: a method for repairing internal defects of a large aluminum alloy casting comprises the following steps:
s1, carrying out three-dimensional flaw detection on the large aluminum alloy casting, and determining the size data of one or more internal defects and the position data in the casting; the internal defects include: pores, shrinkage cavities or local shrinkage porosity;
s2, preparing a repairing passage to communicate the internal defects of the aluminum alloy casting with the external surface of the casting;
s3, utilizing the repair channel obtained in the S2 to densely fill the repair material into the internal defects and the repair channel; filling the area close to the surface of the casting with solid powder and the area far away from the surface of the casting with a mixture of solid powder and solid particles inside the repair channel;
and S4, exciting the self-propagating reaction of the repair material to obtain the repaired tissue with mechanical property close to that of the casting body material.
In the method for repairing internal defects of large aluminum alloy castings, the internal defects in the step S1 preferably include: pores, shrinkage cavities or local shrinkage porosity.
In the method for repairing internal defects of large aluminum alloy castings, preferably, the repair passage in the step S2 is simultaneously communicated with a plurality of internal defects;
in the method for repairing internal defects of large aluminum alloy castings, preferably, in step S2, the diameter Dx of the repair channel is 3-10mm, and the depth Sx of the repair channel is 5-20 times of Dx;
in the method for repairing internal defects of large aluminum alloy castings, the material composition of the solid particles in the step S3 is preferably the same as that of the aluminum alloy casting body, or the same as that of the solid powder.
In the method for repairing the internal defects of the large aluminum alloy casting, preferably, if the material components of the solid particles are the same as the aluminum alloy casting body, the particle size of the solid powder is less than 200 microns, and the particle size of the solid particles is 0.2-2 mm; the solid particles have a particle size 10 to 25 times that of the solid powder and less than 10% of the diameter of the repair tunnel. The concrete method for densely filling the repair material to the internal defects comprises the following steps: (a) calculating the total filling mass Mt of the repair material; defining defect filling mass Mf, repairing channel repairing mass Mx, and calculating the total filling mass of the repairing material from Mt to Mf + Mx; (b) filling solid powder repair materials with mass Mf into the internal defects by using a repair channel; (c) filling solid powder with mass Mxa and solid particles mixed repair material into the repair channel, wherein Mxa is equal to C.Mx, and 0.4< C is less than or equal to 0.7; (d) the repair tunnel was filled with a mass Mxb of solid powdered repair material, Mxb ═ (1-C) · Mx.
In the method for repairing the internal defect of the large aluminum alloy casting, preferably, if the material components of the solid particles are the same as the solid powder, the solid particles are cylinders with the diameter Dg and the height Hg, the Dx is more than 0.5 and less than 0.9Dx, and the Dx is less than Hg, wherein the Dx is the diameter of the repairing channel. The concrete method for densely filling the repair material in the internal defect position comprises the following steps: (a) calculating the total filling mass Mt of the repair material; defining defect filling mass Mf, repairing channel repairing mass Mx, and calculating the total filling mass of the repairing material from Mt to Mf + Mx; (b) filling solid powder repair materials with mass Mf into the internal defects by using a repair channel; (c) defining the depth Sx of a repair channel, and sequentially filling N cylindrical solid particles into the repair channel to meet the condition that 0.5Sx is less than or equal to 0.7Sx and N.Hg; defining the mass of a single cylindrical solid particle as M0, and calculating the total mass Mxa of the filled cylindrical solid particles from Mxa-N.M 0; (d) filling a repair channel with Mxb mass of solid powdered repair material, Mxb ═ Mx-Mxa; (e) pressure is applied to the upper surface of the repair material adjacent the surface of the casting to increase the compaction of the solid powder fill beneath the solid particles.
In the method for repairing internal defects of large aluminum alloy castings, the area of the linear heat source in the step S4 is preferably less than 10% of the area of the cross section of the repair channel.
In the method for repairing internal defects of large aluminum alloy castings, in the step S4, preferably, in the self-propagating reaction process of the repair material, pressure of 0.1-0.5Mpa is applied to the upper surface of the filled repair material.
In the method for repairing internal defects of large aluminum alloy castings, preferably, in step S4, the specific process of exciting the reduction exothermic reaction of the repair material by using the linear heat source includes: (a) inserting one end of a tungsten rod in a room temperature state into a solid powder filling area on the upper part of the repair material filled in the step S3; (b) the other end of the pure tungsten rod is provided with a heating device to raise the overall temperature of the tungsten rod to 1000-2500 ℃; (c) the high temperature of the pure tungsten rod enables the solid powder repair material to reach the temperature condition of self-propagating reaction.
Drawings
FIG. 1 is a flow chart of a method for repairing defects in a casting according to the present invention;
FIG. 2 is a schematic of a monolithic subframe containing internal defects;
FIG. 3 is an enlarged partial cross-sectional view of an internal defect;
FIG. 4 is an enlarged partial cross-sectional view after filling with a repair material;
FIG. 5 is a schematic view of a cylindrical solid particle filled in the middle of a filling zone;
FIG. 6 is a schematic view of a filling zone for filling hollow cylindrical solid particles at the middle section;
FIG. 7 metallographic SEM image of a repair tissue;
figure 8 EDS picture of repaired tissue.
In the figure, 1, the integrated subframe; 2, internal defects; 3, matrix organization; 4, repairing the channel; 5, filling the lower section of the area; 6, filling the middle section of the area; 7, filling the upper section of the area; 8, repairing tissues; 9, a metal network; 10, buffering an interface; 11, cylindrical solid particles; 12, hollow cylindrical solid particles; 13, internal passages.
Detailed Description
The invention discloses a method for repairing internal defects of a large aluminum alloy casting, which can solve the problems of high cost for repairing the internal defects of the aluminum alloy casting, low compactness of a material in a repairing area and poor mechanical property of the material in the repairing area.
As shown in FIG. 1, the method for repairing the internal defects of the casting comprises the following steps:
s1, carrying out three-dimensional flaw detection on the large aluminum alloy casting, and determining the size and position data of one or more internal defects;
s2, preparing a repair channel which communicates one internal defect with the outer surface of the casting or communicates a plurality of internal defects with the outer surface of the casting simultaneously; the diameter Dx of the repair channel is 3-10mm, and the depth Sx of the repair channel is 5-20 times of Dx;
s3, conveying the repairing material with the mass Mt to the internal defect by using the repairing channel obtained in the S2, and densely filling the internal defect and the repairing channel; the repair material comprises two forms of solid powder and solid particles; filling the area close to the surface of the casting with solid powder and the area far away from the surface of the casting with a mixture of solid powder and solid particles inside the repair channel;
s4, exciting the reduction exothermic reaction of the repair material by using a linear heat source; the exothermic reaction melts the repair material and solidifies the repair material into a repaired tissue with mechanical property close to that of the casting body material under the condition of externally applying pressure; the area of the linear heat source is less than 10% of the cross-sectional area of the restoration channel.
The internal defect in step S1 includes: pores, shrinkage cavities or local shrinkage porosity.
The repair channel in the step S2 is simultaneously communicated with a plurality of internal defects; the diameter Dx of the repair channel is 3-10mm, and the depth Sx of the repair channel is 5-20 times of Dx.
The material composition of the solid particles in the step S3 is the same as that of the aluminum alloy casting body, or the solid powder.
If the material components of the solid particles are the same as the matrix structure 3 of the aluminum alloy casting body, the particle size of the solid powder is less than 200 microns, and the particle size of the solid particles is 0.2-2 mm; the particle size of the solid particles is 10 to 25 times that of the solid powder; the particle size of the solid particles is less than 10% of the diameter of the repair channel. The concrete method for densely filling the repair material in the internal defect position comprises the following steps: (a) calculating the total filling mass Mt of the repair material; defining defect filling mass Mf, repairing channel repairing mass Mx, and calculating the total filling mass of the repairing material from Mt to Mf + Mx; (b) filling solid powder repair materials with mass Mf into the repair channel; (c) filling solid powder with mass Mxa and solid particles mixed repair material into the repair channel, wherein Mxa is equal to C.Mx, and 0.4< C is less than or equal to 0.7; (d) the repair tunnel was filled with a mass Mxb of solid powdered repair material, Mxb ═ (1-C) · Mx.
If the material components of the solid particles are the same as the solid powder, the solid particles are cylinders with the diameter Dg and the height Hg, 0.5Dx is more than 0.9Dx and less than 0.9 Dg, and Dx is less than Hg, wherein Dx is the diameter of the repair channel. The concrete method for densely filling the repair material in the internal defect position comprises the following steps: (a) calculating the total filling mass Mt of the repair material; defining defect filling mass Mf, repairing channel repairing mass Mx, and calculating the total filling mass of the repairing material from Mt to Mf + Mx; (b) filling solid powder repair materials with mass Mf into the repair channel; (c) defining the depth Sx of a repair channel, and sequentially filling N cylindrical solid particles into the repair channel to meet the condition that 0.5Sx is less than or equal to 0.7Sx and N.Hg; defining the mass of a single cylindrical solid particle as M0, and calculating the total mass Mxa of the filled cylindrical solid particles from Mxa ═ N.M 0; (d) filling a repair channel with Mxb mass of solid powdered repair material, Mxb ═ Mx-Mxa; (e) pressure is applied to the upper surface of the repair material adjacent the surface of the casting to increase the compaction of the solid powder fill beneath the solid particles.
The area of the linear heat source of the step S4 is less than 10% of the cross-sectional area of the repair channel.
And step S4, in the self-propagating reaction process of the repair material, applying pressure of 0.1-0.5Mpa on the upper surface of the filled repair material.
In the step S4, the specific process of exciting the reduction exothermic reaction of the repair material by using the linear heat source is as follows: (a) inserting one end of a tungsten rod in a room temperature state into a solid powder filling area on the upper part of the repair material filled in the step S3; (b) the other end of the pure tungsten rod is provided with a heating device to raise the overall temperature of the tungsten rod to 1000-; (c) the high temperature of the tungsten rod causes the solid powder to reach the temperature conditions at which the self-propagating reaction occurs.
In order to ensure that the self-propagating reaction of the repairing material can be carried out uninterruptedly, the material component proportion, the particle sizes or shapes of the solid powder and the solid particles, and the specific gravity setting of the solid powder and the solid particles of the repairing material are specially designed. On the contrary, the self-propagating reaction may be interrupted for reasons including: (1) the repaired casting absorbs excessive heat in the self-propagating reaction process, so that the temperature of the repairing material is lower than the reaction critical temperature; (2) the repair material is not filled densely, and discontinuous faults exist; (3) if the material components of the solid particles in the repair material are the same as those of the aluminum alloy casting body, the solid particles are melted and phase-changed to absorb excessive heat, so that the temperature of the repair material is lower than the reaction critical temperature.
The technical solutions in the embodiments of the present invention will be described in detail below with reference to the accompanying drawings in the embodiments of the present invention. The restoration object in the embodiment is an integral auxiliary frame made of aluminum alloy. Of course, the application range of the present invention is not limited to such materials and types of parts, and the repair material in the embodiment is not limited to only the following material components, nor is the size of internal defects limited to only the following cases; the present invention is explained only by referring to these technical features as specific examples.
The first embodiment.
The filled repair material comprises repair material A and repair material B, wherein the repair material A is a mixture of more than one solid powder, and the repair material B is a mixture of solid powder and solid particles. The repair material A is prepared by uniformly stirring and fully mixing the following raw materials in percentage by weight: 26% of Al powder and 74% of Fe2O3 powder; the average particle sizes of the Al powder and the Fe2O3 powder were 100 μm and 10 μm, respectively. The reason for adopting the materials and the proportion is that the Fe of the reaction product is in grid distribution, as shown in figure 7, the high-temperature short-time tensile strength, the creep strength, the room temperature and the high-temperature strength of the Al alloy can be improved; and the smaller grain diameter of the Fe2O3 powder can ensure that the self-propagating reaction can be smoothly carried out.
The reaction equation of the self-propagating reaction is as follows:
Fe 2 O 3 +2Al＝Al 2 O 3 +2Fe
the implementation steps comprise:
(1) the integrated subframe 1 was inspected three-dimensionally to determine that it had an internal defect 2 located in the middle of the back beam, as shown in figure 2. The minimum depth of the internal defect 2 from the surface of the frame is 30mm and the maximum diameter is 50 mm.
(2) Processing a repair channel 4 for communicating internal defects of the casting and the outer surface of the casting on the surface of the integral auxiliary frame 1 by using a drill bit with the diameter of 6mm, wherein the repair channel is shown in figure 3; the depth Sx of the repair channel 4 is 32mm, and the diameter Dx of the repair channel 4 is 6 mm.
(3) Preparing a repairing material A and a repairing material B; the repair material A is prepared by fully mixing Al powder and Fe2O3 powder, and the particle size of solid powder in the repair material A is less than 200 microns. The repair material B is formed by adding solid particles into the repair material A, wherein the solid particles have the same components as the aluminum alloy casting body material and have the particle size of 0.2-2 mm; and the particle size of the solid particles is 10 to 25 times that of the solid powder, and the particle size of the solid particles is less than 10% of the diameter of the repair channel. In the repair material B, the specific gravity of the solid particles is less than 20%.
(4) The internal defect 2 and the repair channel 4 jointly form a filling area, and the filling area comprises a filling area lower section 5, a filling area middle section 6 and a filling area upper section 7; the length of the lower section 5 of the filling area covers the whole length of the original internal defect 2, and the middle section 6 of the filling area and the upper section 7 of the filling area together cover the whole length of the original repair channel 4; wherein the filling zone mid section 6 occupies more than 50% of the total length of the repair channel 4. First, the lower filling-zone segment 5 is filled with the repair material a, then the middle filling-zone segment 6 is filled with the repair material B, and finally the upper filling-zone segment 7 is filled again with the repair material a.
The repair material a is filled in the lower section 5 of the filling area because: the solid powder of the repair material A has small particle size and can smoothly enter the tiny cracks of the internal defects 2.
Filling the repair material B in the middle section 6 of the filling area has 3 advantages: firstly, the solid particles in the repair material B absorb heat in the self-propagating reaction process, so that the reaction rate of the self-propagating reaction is reduced, and the cracking of a casting caused by violent reaction is avoided; secondly, after the solid particles absorb heat, solid-liquid phase change occurs, so that tiny gaps in the repair area can be filled, and the tissue density of the repair area is improved; finally, the melted solid particles solidify again, forming a metal network 9 in the tissue of the repair area as shown in fig. 7, increasing the strength of the repair area; and the iron content in the tissues of the repair area was increased as shown in fig. 8.
The upper section 7 of the filling zone is filled with repair material a because: the solid powder of the repair material A has smaller particle size and is easier to be excited to self-propagating reaction.
(5) Preheating the area adjacent to the repair area at the preheating temperature of 300 ℃ and 400 ℃; and then inserting a linear heat source into the upper section 7 of the filling area, raising the temperature of the insertion section of the linear heat source to 1000-2500 ℃ by utilizing a high-frequency magnetic induction heating or resistance heating principle, exciting the self-propagating reaction of the repair material, and finishing the self-propagating reaction according to the sequence of the upper section 7 of the filling area, the middle section 6 of the filling area and the lower section 5 of the filling area.
The linear heat source is preferably made of a pure tungsten rod, and the sectional area of the linear heat source is less than 10% of that of the restoration channel.
In the self-propagating reaction process of the repair material, continuously applying pressure of 0.1-0.5Mpa on the upper surface of the filled repair material.
Example two.
The difference between the second embodiment and the first embodiment is that, as shown in fig. 5, the material composition of the repair material B filled in the middle section 6 of the filling area is the same as that of the repair material A, but the solid particles of the repair material B are pressed into a cylinder shape by a mold, and the pressing pressure is 15-200 Mpa; the cylindrical solid particles 11 have an outer diameter of 5mm and a height of 7 mm. And sequentially putting 4 cylindrical solid particles 11 into the middle section 6 of the filling area of the repair channel 4.
The advantages of pressing the repair material B into the shape and size are: firstly, compared with the repair material A of solid powder, the strength and density of the pressed cylindrical solid particles 11 are higher, and the pressed cylindrical solid particles can be conveniently and accurately filled into the repair channel 4; moreover, the special overall dimension of the cylindrical solid particles 11 enables the particles to enter the restoration channel 4 only at a specific pose, and once the particles enter the restoration channel 4, the particles cannot turn over inside the restoration channel 4, so that the success rate of correct filling can be improved; meanwhile, a buffer interface 10 exists between the adjacent cylindrical solid particles 11, which can reduce the reaction rate of the self-propagating reaction and avoid the cracking of the casting caused by violent reaction; finally, the pressure applied to the upper surface of the filled repair material is transmitted to the lower filling region section 5, and compared with the repair material B in the first embodiment, the pressure loss of the cylindrical solid particles 11 in the present embodiment is less, so that the filling density of the lower filling region section 5 can be further improved.
Example three.
Example three differs from example two in that the material composition of the repair material B filled in the middle section 6 in the filling zone is the same as the repair material a, but the solid particles of the repair material B are compressed into a hollow cylindrical shape, the inner diameter of the hollow cylindrical solid particles 12 being 2mm, as shown in fig. 6.
Sequentially placing 4 hollow cylindrical solid particles 12 into the filling area middle section 6 of the repairing channel 4 to generate an internal channel 13, wherein in the process of filling the repairing material A into the filling area upper section 7, the solid powder of the repairing material A enters the internal channel 13;
in the first and second embodiments, the propagation direction of the self-propagating reaction combustion wave is along the repair tunnel 4 in the filling region middle section 6. However, in the third embodiment, since the density of the repair material B is much higher than that of the repair material a after being pressed and formed by the mold, the propagation speed of the self-propagating reaction combustion wave in the repair material a is much higher than that of the repair material B, so that the self-propagating reaction inside the 4 hollow cylindrical solid particles 12 can be sequentially activated by the repair material a in the internal passage 13; further in the third embodiment, the combustion wave propagates in the repair channel 4 mainly in the channel radial direction. The advantages of the above features are also: the self-propagating reaction of the middle section 6 and the lower section 5 of the filling area can be synchronously carried out, so that the heat release in the reaction process is more stable, and the beneficial effects of more uniform tissue structure and reduced residual stress of the repair area are achieved.
Claims (9)
1. A method for repairing internal defects of large aluminum alloy castings is characterized by comprising the following steps: the method comprises the following steps:
s1, carrying out three-dimensional flaw detection on the large aluminum alloy casting, and determining the size data of one or more internal defects and the position data in the casting; the internal defects include: pores, shrinkage cavities or local shrinkage porosity;
s2, preparing a repair channel which communicates one internal defect with the outer surface of the casting or communicates a plurality of internal defects with the outer surface of the casting simultaneously; the diameter Dx of the repair channel is 3-10mm, and the depth Sx of the repair channel is 5-20 times of Dx;
s3, conveying the repairing material with the mass Mt to the internal defect by using the repairing channel obtained in the S2, and densely filling the internal defect and the repairing channel;
s4, exciting the self-propagating reaction of the repair material by using a linear heat source, wherein the area of the linear heat source is less than 10% of the area of the cross section of the repair channel; in the self-propagating reaction process of the repair material, 0.1-0.5Mpa of pressure is applied on the upper surface of the filled repair material.
2. The method for repairing the internal defects of the large aluminum alloy casting according to claim 1, wherein the method comprises the following steps: the repair material comprises solid powder, a mixture of the solid powder and solid particles, wherein the particle size of the solid particles is 10 to 100 times that of the solid powder;
the solid powder is a mixture of solid powders of more than one material, all of which have a particle size of less than 200 microns;
the solid particles are metal particles made of a single material or are obtained by mixing and pressing a plurality of solid powders, and the particle size of the solid particles is 0.2-2 mm;
inside the internal defect and repair passage, the area near the casting surface is filled with solid powder, and the area far from the casting surface is filled with a mixture of solid powder and solid particles.
3. The method for repairing the internal defects of the large aluminum alloy casting according to claim 1, characterized by comprising the following steps: in the step S3, the solid particles have the same material composition as the aluminum alloy casting bulk material, or the same material composition as the solid powder material.
4. The method for repairing the internal defects of the large aluminum alloy casting according to claim 3, wherein the method comprises the following steps: in the step S3, if the solid particles have the same composition as the aluminum alloy casting bulk material, the particle size of the solid powder is less than 200 μm, and the particle size of the solid particles is 0.2-2 mm; the particle size of the solid particles is 10 to 25 times that of the solid powder; the particle size of the solid particles is less than 10% of the diameter of the repair channel.
5. The method for repairing the internal defects of the large aluminum alloy casting according to claim 4, wherein the method comprises the following steps: the method is characterized in that a repairing material is densely filled in the internal defect part, and the specific process is as follows:
(a) calculating the total filling mass Mt of the repair material; defining defect filling mass Mf, repairing channel repairing mass Mx, and calculating the total filling mass of the repairing material from Mt to Mf + Mx;
(b) filling solid powder repair materials with mass Mf into the repair channel;
(c) filling solid powder with mass Mxa and solid particles mixed repair material into the repair channel, wherein Mxa is equal to C.Mx, and 0.4< C is less than or equal to 0.7;
(d) the repair tunnel was filled with a mass Mxb of solid powdered repair material, Mxb ═ (1-C) · Mx.
6. The method for repairing the internal defects of the large aluminum alloy casting according to claim 3, wherein the method comprises the following steps: in the step S3, if the solid particles and the solid powder material have the same components, the solid particles are cylinders with diameter Dg and height Hg, where 0.5Dx < Dg is less than or equal to 0.9Dx, where Dx is the diameter of the repair channel; dx < Hg.
7. The method for repairing the internal defects of the large aluminum alloy casting according to claim 6, wherein the method comprises the following steps: the method is characterized in that a repairing material is densely filled in the internal defect part, and the specific process is as follows:
(a) calculating the total filling mass Mt of the repair material; defining defect filling mass Mf, repairing channel filling mass Mx, and calculating the total filling mass of the repairing material from Mt to Mf + Mx;
(b) filling solid powder repair materials with mass Mf into the repair channel;
(c) defining the depth Sx of a repair channel, and sequentially filling N cylindrical solid particles into the repair channel to meet the condition that 0.5Sx is less than or equal to 0.7Sx and N.Hg; defining the mass of a single cylindrical solid particle as M0, and calculating the total mass Mxa of the filled cylindrical solid particles from Mxa-N.M 0;
(d) applying pressure to the upper surface of the solid particulates adjacent the surface of the casting to increase the solidity of the solid powder charge below the solid particulates;
(e) the repair tunnel was filled with a mass of Mxb solid powdered repair material, Mxb ═ Mx-Mxa.
8. The method for repairing the internal defects of the large aluminum alloy casting according to claim 1, wherein the method comprises the following steps: in step S4, the linear heat source is a tungsten rod, and the specific method for exciting the reduction exothermic reaction of the repair material by using the linear heat source includes:
(a) inserting one end of a tungsten rod in a room temperature state into a solid powder filling area on the upper part of the repair material filled in the step S3;
(b) arranging a heating device at the other end of the pure tungsten rod to raise the overall temperature of the tungsten rod to 1000-;
(c) the high temperature of the tungsten rod causes the solid powder to reach the temperature conditions at which the self-propagating reaction occurs.
9. The method for repairing the internal defects of the large aluminum alloy casting according to claim 6, wherein the method comprises the following steps: the solid particles in the step S3 are hollow cylinders, and define a diameter Dgw, an inner diameter Dgn and a height Hg of the hollow cylinders; the Dx is less than 0.5 and less than Dgw and less than or equal to 0.9Dx, the Dx is less than Hg, and the Dx is less than 0.5mm and less than Dgn and less than or equal to 0.5 Dgw.
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