CN112981286B - Hole extrusion strengthening method of aluminum alloy thick plate and lubricant for method - Google Patents
Hole extrusion strengthening method of aluminum alloy thick plate and lubricant for method Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
- C10M169/00—Lubricating compositions characterised by containing as components a mixture of at least two types of ingredient selected from base-materials, thickeners or additives, covered by the preceding groups, each of these compounds being essential
- C10M169/04—Mixtures of base-materials and additives
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
- C10M177/00—Special methods of preparation of lubricating compositions; Chemical modification by after-treatment of components or of the whole of a lubricating composition, not covered by other classes
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
- C10M2201/00—Inorganic compounds or elements as ingredients in lubricant compositions
- C10M2201/04—Elements
- C10M2201/041—Carbon; Graphite; Carbon black
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
- C10M2201/00—Inorganic compounds or elements as ingredients in lubricant compositions
- C10M2201/06—Metal compounds
- C10M2201/065—Sulfides; Selenides; Tellurides
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
- C10M2209/00—Organic macromolecular compounds containing oxygen as ingredients in lubricant compositions
- C10M2209/10—Macromolecular compoundss obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
- C10M2209/103—Polyethers, i.e. containing di- or higher polyoxyalkylene groups
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
- C10M2217/00—Organic macromolecular compounds containing nitrogen as ingredients in lubricant compositions
- C10M2217/04—Macromolecular compounds from nitrogen-containing monomers obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
- C10M2217/044—Polyamides
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Abstract
The invention provides a hole extrusion strengthening method of an aluminum alloy thick plate and a lubricant used for the method, wherein an anti-friction coating with different lubricating properties is formed on the wall of a connecting hole in a coating mode, and the friction coefficient of the surface of the coating is larger than that of an inner layer, so that a more uniform friction coefficient and better lubricating property can be provided when the coating is worn, the probability of scratching of the hole wall or bonding of the hole wall and an extrusion rod is reduced, the hole extrusion strengthening effect is ensured, and the production efficiency is improved.
Description
Technical Field
The invention belongs to the technical field of aluminum alloy processing, and particularly relates to a hole extrusion strengthening method of an aluminum alloy thick plate and a lubricant suitable for the method.
Background
Most components of an aircraft are assembled by installing fasteners in the attachment holes. And the periphery of the hole is a high stress concentration area, so that the problems of fatigue fracture failure and the like are easy to occur. With the rapid development of aerospace industry, the requirements for aircraft fatigue-resistant manufacturing technology are continuously increasing. In the actual production process, a hole extrusion technology is often adopted to reinforce the holes, and the hole extrusion reinforcement technology continuously and uniformly extrudes the holes through a hard extrusion rod to form an elastic-plastic deformation layer and a processing hardening layer with certain depth around the holes, so that the fatigue life of the holes is prolonged.
In order to prevent the squeeze bar from scratching or bonding the walls of the hole during the hole extrusion process, a lubricant is generally uniformly applied to the surface of the hole wall before extrusion, and the lubricant is dried to form a dry film, thereby reducing the friction between the squeeze bar and the hole wall. However, in the actual production process, due to the high extrusion amount required by the hole extrusion strengthening process and the large extrusion force, the phenomenon that the hole wall is scratched or the hole wall is bonded with an extrusion rod often inevitably occurs, and the extrusion strengthening effect is seriously reduced.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a hole extrusion strengthening method of an aluminum alloy thick plate and a lubricant suitable for the method. In the process of extrusion strengthening of holes of the aluminum alloy thick plate, the extrusion rod is in interference fit with the connecting hole, the extrusion rod and the connecting hole can generate obvious strengthening resistance, and the strengthening resistance has important influences on strengthening tension, hole wall axial stress distribution, orifice material extrusion amount and the like, and directly influences the cold extrusion fatigue strengthening effect of the holes. The strengthening resistance is very sensitive to the friction coefficient of the extrusion rod and the connecting hole wall, and even small-amplitude change of the friction coefficient can cause obvious change of the strengthening resistance to influence the strengthening effect.
The inventors of the present application have surprisingly found in their research that the wear-reducing coating formed by drying the lubricant applied to the walls of the bore is very thin and that the pressure exerted by the extrusion rod on the surface of the coating during extrusion is unevenly distributed, which causes a difference in wear of the wear-reducing coating during extrusion and even partial wear-through. When the abrasion or wearing-through occurs, the friction coefficient between the extrusion rod and the wall of the connecting hole is changed, and the strengthening effect is influenced.
In order to ensure the hole extrusion strengthening effect, the inventor of the application provides a hole extrusion strengthening method of an aluminum alloy thick plate and a lubricant from the perspective of uniformizing friction coefficients, and a wear-reducing coating with difference from a bottom layer to the surface friction coefficient increase is coated on a hole wall, so that a more uniform friction coefficient and better lubricating performance are provided when the wear-reducing coating is worn, the risk that the hole wall is scratched or the hole wall is bonded with an extrusion rod is reduced, and the hole extrusion strengthening effect is ensured.
The purpose of the invention is realized by the following technical scheme:
a hole extrusion strengthening method of an aluminum alloy thick plate comprises the following steps:
coating a lubricant on the wall of the hole to be reinforced;
drying, wherein the lubricant is dried to form at least two antifriction coating layers with different friction coefficients, and in the antifriction coating layers, the friction coefficient of the antifriction coating layer positioned on the outer layer is larger than that of the antifriction coating layer positioned on the inner layer;
and extruding and strengthening the hole to be strengthened.
According to the embodiment of the invention, the total thickness of the formed antifriction coating is 80-160 μm, such as 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm or 160 μm.
According to the embodiment of the present invention, the thicknesses of the at least two friction reducing coatings with different friction coefficients formed may be the same or different, and are preferably the same or similar.
According to the embodiment of the invention, the friction coefficient of the antifriction coating positioned on the outer layer is 0.15-0.20.
According to the embodiment of the invention, the friction coefficient of the antifriction coating positioned on the inner layer is 0.06-0.10.
According to an embodiment of the invention, the method comprises the steps of:
coating at least two lubricants on the hole wall of the hole to be reinforced, wherein the solid lubricating component content of the two lubricants is different;
drying, wherein the lubricant is dried to form at least two antifriction coating layers with different friction coefficients, and in the antifriction coating layers, the friction coefficient of the antifriction coating layer positioned on the outer layer is larger than that of the antifriction coating layer positioned on the inner layer;
the hole to be reinforced is extrusion reinforced (e.g., with an extrusion bar).
According to the embodiment of the invention, the friction coefficients of the formed antifriction coatings are different due to the different contents of the solid lubricating components in the two lubricants, and specifically, the friction coefficient of the formed antifriction coating is smaller as the content of the solid lubricating components in the lubricants is higher, so that at least two lubricants with different contents of the solid lubricating components are coated, and at least two antifriction coatings with different friction coefficients can be formed after the lubricants are dried.
According to an embodiment of the present invention, the lubricant may be selected from the lubricants defined hereinafter.
According to an embodiment of the present invention, the aluminum alloy is selected from various types of aluminum alloys known in the art, in particular, the aluminum alloy is selected from 7000 series aluminum alloys; wherein the 7000 series aluminum alloy is at least one selected from the group consisting of 7055 aluminum alloy, 7085 aluminum alloy, 7150 aluminum alloy, 7A55 aluminum alloy, 7A85 aluminum alloy, 7B50 aluminum alloy, 7075 aluminum alloy, 7050 aluminum alloy, 7010 aluminum alloy, and 7A01 aluminum alloy.
According to the embodiment of the invention, the thickness of the aluminum alloy thick plate is 30-100 mm, such as 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm or 100 mm.
According to an embodiment of the invention, the pore diameter of the pores to be reinforced is 6-20 mm, such as 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm or 20 mm.
According to an embodiment of the invention, the hole wall surface roughness of the hole to be strengthened is Ra0.2-Ra1.6, such as Ra1.6, Ra0.8, Ra0.4 or Ra0.2.
According to an embodiment of the invention, the holes to be reinforced are extrusion-reinforced according to HB/Z170-.
Illustratively, the extrusion strengthening of the hole to be strengthened comprises the following steps:
an extrusion rod (e.g., a tapered metal mandrel) is inserted into the hole to be strengthened, and mechanical pressure is applied to the end of the extrusion rod to cause the maximum diameter portion of the extrusion rod to pass through the hole to be strengthened and then stop pressurizing.
According to an embodiment of the present invention, the extrusion amount of the extrusion strengthening of the hole to be strengthened is 2.5 to 3.8%, for example 3.0%.
According to an embodiment of the invention, the method comprises the steps of:
1) uniformly coating a first lubricant on the wall of a hole to be reinforced, and drying to form a first antifriction coating;
2) uniformly coating the second lubricant on the first antifriction coating, and drying to form a second antifriction coating; wherein the first lubricant and the second lubricant have different contents of solid lubricating components, and the friction coefficient of the second friction reducing coating is larger than that of the first friction reducing coating;
3) and extruding and reinforcing the hole to be reinforced by using an extruding rod.
According to an embodiment of the invention, the method further comprises the step of forming a transitional friction reducing coating between the first friction reducing coating and the second friction reducing coating, the transitional friction reducing coating having a coefficient of friction between the coefficients of friction of the first friction reducing coating and the second friction reducing coating.
According to the embodiment of the invention, when the transitional wear-reducing coating is 1 layer, the friction coefficient of the transitional wear-reducing coating is between the friction coefficients of the first wear-reducing coating and the second wear-reducing coating; if the transitional antifriction coating is n layers, the friction coefficient of the transitional antifriction coating is between the friction coefficients of the first antifriction coating and the second antifriction coating, the friction coefficient of the transitional antifriction coating closer to the first antifriction coating is smaller, the friction coefficient of the transitional antifriction coating closer to the second antifriction coating is larger, and n is larger than or equal to 2.
It is understood that a transitional lubricant may also be applied to form a transitional friction reducing coating before the second friction reducing coating is formed, the transitional friction reducing coating having a coefficient of friction intermediate that of the first friction reducing coating and the second friction reducing coating, thereby forming an intermediate layer having a transitional coefficient of friction. That is, the hole wall of the hole to be reinforced is coated with an anti-friction coating comprising at least two layers having different coefficients of friction, and of these anti-friction coatings, the coefficient of friction is greater at the outer layer than at the inner layer.
According to an embodiment of the invention, the first lubricant and the second lubricant are selected from the lubricants described below. Preferably, the first lubricant and the second lubricant each include a solid lubricating component, a cured resin, and a solvent, but the solid lubricating component content in the first lubricant and the second lubricant is different, thereby providing friction reducing coatings of different coefficients of friction.
According to the embodiment of the present invention, the content of the solid lubricating component in the first lubricant forming the first friction reducing coating is larger than the content of the solid lubricating component in the second lubricant forming the second friction reducing coating, so that after the first lubricant and the second lubricant are dried, the first friction reducing coating formed contains more solid lubricating component than the second friction reducing coating formed, and thus the friction coefficient is low.
The invention also provides a lubricant which is particularly suitable for the hole extrusion strengthening method of the aluminum alloy thick plate, and the preparation raw material of the lubricant comprises the following components in parts by mass: (a) 20-70 parts of a solid lubricating component; (b) 50-120 parts of curing resin; and (c) 70-120 parts of a solvent.
According to the embodiment of the invention, the preparation raw materials of the lubricant comprise the following components in parts by mass: (a) 20-55 parts of a solid lubricating component; (b) 70-110 parts of curing resin; and (c) 80-100 parts of a solvent.
Illustratively, the solid lubricating component (a) is added in an amount of 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, or 70 parts.
Illustratively, the addition amount of (b) the curing resin is 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, 85 parts, 90 parts, 95 parts, 100 parts, 105 parts, 110 parts, 115 parts, or 120 parts.
Illustratively, the amount of (c) solvent added is 70 parts, 75 parts, 80 parts, 85 parts, 90 parts, 95 parts, 100 parts, 115 parts, or 120 parts.
According to an embodiment of the invention, the solid lubricating component is selected from at least one of molybdenum disulphide, flake graphite, tungsten disulphide, hexagonal boron nitride and polytetrafluoroethylene.
According to an embodiment of the invention, the solid lubricating component is selected from at least two of molybdenum disulphide, flake graphite, tungsten disulphide and hexagonal boron nitride.
Further, the solid lubricating component is selected from flake graphite and tungsten disulfide. The scale graphite is a natural solid lubricant with a layered structure, is similar to fish phosphorus in shape, belongs to a hexagonal system, is in a layered structure, and has good performances of high temperature resistance, heat conduction, lubrication, plasticity, acid and alkali resistance and the like; the structure of the tungsten disulfide is similar to that of graphite, and the tungsten disulfide has a very low friction coefficient, and high extreme pressure resistance and oxidation resistance.
Illustratively, the mass part ratio of the crystalline flake graphite to the tungsten disulfide is (15-35): 5-20), for example, (15-25): 5-15) or (25-35): 10-15.
According to an embodiment of the present invention, the particle size of the solid lubricating component is 0.5 μm to 500 μm.
Preferably, the particle size of the solid lubricating component is 40 μm to 150 μm.
Illustratively, the particle size of the crystalline flake graphite is 40-80 μm, and the purity is greater than or equal to 96.5%.
Illustratively, the particle size of the tungsten disulfide is 45-100 μm.
According to an embodiment of the present invention, the cured resin is at least one selected from the group consisting of polyimide resin, polyamide resin, polyurethane, phenol resin, and epoxy resin.
Further, the cured resin is at least one of an epoxy resin and a polyimide resin, and still further, the cured resin is an epoxy resin and a polyimide resin.
Illustratively, the mass part ratio of the epoxy resin to the polyimide resin is (20-30): 50-80).
According to an embodiment of the present invention, the solid lubricating component may be uniformly dispersed in the cured resin. The addition of the cured resin allows the lubricant to dry to form an anti-friction coating that can provide some compensation for the uneven surface of the walls of the holes to be reinforced, reducing friction during extrusion and improving reinforcement uniformity. Meanwhile, the cured resin has excellent mechanical properties and high and low temperature resistance, is particularly outstanding in severe environments such as high temperature, high pressure and the like, is very suitable for extrusion reinforcement, and has the advantages of high load resistance, low friction coefficient, high toughness, high and low temperature resistance and the like due to the coordination of all components.
According to an embodiment of the present invention, the solvent is selected from at least one of acetone, ethanol, butanol or xylene.
Illustratively, the lubricant comprises the following components in parts by mass:
15-35 parts of flake graphite
5-20 parts of tungsten disulfide
20-30 parts of polyimide
50-80 parts of epoxy resin
80-100 parts of a solvent.
Illustratively, the lubricant comprises the following components in parts by mass:
15-25 parts of flake graphite
5-15 parts of tungsten disulfide
20-30 parts of polyimide
50-80 parts of epoxy resin
80-100 parts of a solvent.
Illustratively, the lubricant comprises the following components in parts by mass:
25-35 parts of flake graphite
10-15 parts of tungsten disulfide
20-30 parts of polyimide
50-80 parts of epoxy resin
80-100 parts of a solvent.
The invention also provides a preparation method of the lubricant, which comprises the following steps:
dissolving the solidified resin in a solvent, then adding the solid lubricating component, and performing ultrasonic dispersion to obtain the uniformly dispersed lubricant.
According to an embodiment of the invention, the lubricant is cured at a curing temperature and then dried to form a film, forming the friction reducing coating.
Wherein the curing temperature is 110 +/-5 ℃.
The invention also provides the application of the lubricant, which is used in the field of aluminum alloy.
According to the embodiment of the invention, the hole extrusion strengthening method is used in the field of hole extrusion strengthening of the aluminum alloy thick plate, and particularly, the hole extrusion strengthening method is used in the hole extrusion strengthening method of the aluminum alloy thick plate.
The invention has the beneficial effects that:
the invention provides a hole extrusion strengthening method of an aluminum alloy thick plate and a lubricant suitable for the method.
(1) According to the invention, the anti-friction coating with different lubricating properties is formed by coating the hole wall of the hole to be reinforced, and the friction coefficient of the surface of the coating is larger than that of the inner layer, so that a more uniform friction coefficient and better lubricating property can be provided when the coating is worn, the scratch probability of the hole wall or the bonding probability of the hole wall and an extrusion rod is reduced, the hole extrusion reinforcing effect is ensured, and the production efficiency is improved.
(2) The wear-reducing coating disclosed by the invention is prepared by taking micron-sized solid lubricating components (particularly crystalline flake graphite and tungsten disulfide) as a solid lubricant and adding a curing resin, wherein the solid lubricating components have good high-temperature resistance, heat conduction, lubrication, plasticity, acid and alkali resistance and other properties, and simultaneously have very low friction coefficient, higher extreme pressure resistance and oxidation resistance, the curing resin has excellent mechanical properties and high and low temperature resistance, and simultaneously has excellent wear-reducing and wear-resisting properties, particularly has outstanding characteristics under severe environments such as high temperature, high pressure and the like, and is very suitable for extrusion reinforcement, and all components coordinate to act, so that the lubricant has the advantages of high load resistance, low friction coefficient, high toughness, high and low temperature resistance and the like, so that an excellent lubricating effect is provided for extrusion reinforcement, and the extrusion reinforcement effect is further ensured.
Drawings
FIG. 1 shows a fatigue fracture structure at a hole of an aluminum alloy thick plate without hole extrusion strengthening;
FIG. 2 is a fatigue fracture structure at a hole after hole extrusion strengthening of an aluminum alloy slab in example 2;
FIG. 3 is an SEM microstructure at 8mm from a fatigue source in example 2;
FIG. 4 is an SEM microstructure at 8mm from the fatigue source in comparative example 2.
Detailed Description
The present invention will be described in further detail with reference to specific examples. It is to be understood that the following examples are only illustrative and explanatory of the present invention and should not be construed as limiting the scope of the present invention. All the technologies realized based on the above-mentioned contents of the present invention are covered in the protection scope of the present invention.
The experimental methods used in the following examples are all conventional methods unless otherwise specified; reagents, materials and the like used in the following examples are commercially available unless otherwise specified.
In the description of the present invention, it should be noted that the terms "first", "second", etc. are used for descriptive purposes only and do not indicate or imply relative importance.
Example 1
And (4) preparing a lubricant.
The first lubricant comprises the following components in parts by mass:
30 parts of crystalline flake graphite, 15 parts of tungsten disulfide, 22 parts of polyimide, 68 parts of epoxy resin, 80 parts of ethanol and 10 parts of dimethylbenzene.
The second lubricant comprises the following components in parts by mass:
20 parts of crystalline flake graphite, 10 parts of tungsten disulfide, 22 parts of polyimide, 68 parts of epoxy resin, 80 parts of ethanol and 10 parts of dimethylbenzene.
According to the raw material composition of the lubricant, epoxy resin and polyimide are dissolved in a solvent, and then crystalline flake graphite and tungsten disulfide are added and subjected to ultrasonic dispersion to obtain the uniformly dispersed lubricant.
The lubricant disclosed by the embodiment of the invention has the advantages of high load resistance, low friction coefficient, high toughness, high and low temperature resistance and the like, and also has excellent curing performance.
The detection result of the lubricant disclosed by the invention shows that under the condition of 110 +/-5 ℃, the curing time of the first lubricant and the second lubricant is not more than 1 hour, and when the coating thickness is 20-60 mu m, the coating can be dried and formed into a film within 15 minutes.
Example 2
The hole extrusion strengthening of the 7050 aluminum alloy thick plate comprises the following steps:
1) pore to be reinforced: the aperture is 10mm, the smoothness of the hole wall surface is Ra1.6, and the extrusion amount is 1%.
2) Coating the first lubricant of example 1 on the hole wall of the hole to be reinforced, and forming a first antifriction coating with the thickness of 60 mu m after the first lubricant is solidified and dried; the second lubricant of example 1 was applied to the first friction reducing coating layer, and the second lubricant was cured and dried to form a second friction reducing coating layer having a thickness of 50 μm.
3) And extruding and strengthening the holes to be strengthened according to the HB/Z170-2005 hole extrusion strengthening of aviation parts standard: inserting a tapered metal core rod (extrusion rod) into a hole to be reinforced, applying mechanical pressure to the end part of the metal core rod, enabling the maximum diameter part of the metal core rod to pass through the hole of the workpiece, and stopping pressurizing.
Example 3
Example 3 is substantially the same as example 2 except that in step 2), the first lubricant was replaced with a commercial dry film of graphite for cell extrusion having a graphite mass fraction of 20%, and dried to form an antifriction coating having a thickness of 60 μm, and the second lubricant was replaced with a commercial dry film of graphite for cell extrusion having a graphite mass fraction of 13%, and dried to form an antifriction coating having a thickness of 50 μm.
Comparative example 1
Comparative example 1 is substantially the same as example 2 except that a graphite dry film lubricant for pore extrusion (CRC 03094 type) commonly commercially available from CRC Industries, Inc) was coated on the pore walls of the pores to be reinforced in step 2) and dried to form an anti-friction coating having a thickness of 110 μm.
Comparative example 2
Comparative example 2 is substantially the same as example 2 except that only the first lubricant is applied to the pore walls of the pores to be reinforced in step 2), and dried to form an antifriction coating having a thickness of 110 μm.
Comparative example 3
Comparative example 3 is substantially the same as example 2 except that only the second lubricant is applied to the pore walls of the pores to be reinforced in step 2), and dried to form an antifriction coating having a thickness of 110 μm.
The results of testing the products of example 2 and example 3 after extrusion strengthening and observing the walls of the holes to be strengthened after extrusion strengthening show that the extrusion strengthening methods of example 2 and example 3 can achieve good hole extrusion effect, and the products after extrusion strengthening show good fatigue performance, particularly, the fatigue cycle number of example 2 reaches 6.7 × 106Next, the number of fatigue cycles of example 3 was 1.8X 106Next, example 2 is superior to example 3.
The parts extruded and reinforced in the embodiment 2 and the comparative example 1 are detected, and the hole walls of the holes to be reinforced after extrusion are observed, so that the result shows that the hole extrusion reinforcement in the embodiment 2 can realize good hole extrusion effect, and the fatigue life of the parts is improved by 29 times after the extrusion reinforcement (compared with the comparative example 1); as can be seen from FIGS. 1 and 2, the fracture fatigue strip width of the 7050 thick plate which is not subjected to hole extrusion strengthening is about 1.03 μm, the fatigue strip width after strengthening by the example 2 is only 0.45 μm, and the example 2 shows good fatigue performance. Meanwhile, the wear-reducing coating on the hole wall of the hole to be reinforced in comparative example 1 is significantly worse than that of example 2, and a part of the wear-reducing coating of comparative example 1 is worn out, while example 2 has no wear-out phenomenon.
In addition, the detection on the parts subjected to extrusion strengthening in the embodiment 2 and the comparative example 2 shows that the hole extrusion strengthening in the embodiment 2 can achieve a good hole extrusion effect, and after the extrusion strengthening, the fatigue life of the part in the embodiment 2 is improved by nearly 45 times (compared with the comparative example 2); as can be seen from fig. 3 and 4, the example 2 observed a significant fatigue band at the fatigue source of 8mm, while the comparative example 2 observed a significant fracture dimple at the fatigue source of 8mm, thus illustrating that the example 2 exhibited good fatigue performance. The test conducted on the articles of example 2 and comparative example 3 after extrusion strengthening further illustrates that example 2 exhibits good fatigue properties.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (5)
1. A method of hole extrusion strengthening of an aluminum alloy slab, the method comprising the steps of:
uniformly coating a first lubricant on the wall of a hole to be reinforced, and drying to form a first antifriction coating;
uniformly coating the second lubricant on the first antifriction coating, and drying to form a second antifriction coating;
carrying out extrusion strengthening on the hole to be strengthened;
the preparation raw materials of the first lubricant and the second lubricant comprise the following components in parts by mass: (a) 20-70 parts of a solid lubricating component; (b) 50-120 parts of curing resin; 70-120 parts of a solvent; the solid lubricating component is selected from at least two of molybdenum disulfide, crystalline flake graphite, tungsten disulfide, hexagonal boron nitride and polytetrafluoroethylene; the cured resin is selected from at least one of polyimide resin, polyamide resin, polyurethane, phenolic resin and epoxy resin;
wherein the content of the solid lubricating component in the first lubricant forming the first friction reducing coating layer is larger than the content of the solid lubricating component in the second lubricant forming the second friction reducing coating layer;
the friction coefficient of the antifriction coating layer positioned on the outer layer, namely the second antifriction coating layer, is 0.15-0.20, and the friction coefficient of the antifriction coating layer positioned on the inner layer, namely the first antifriction coating layer, is 0.06-0.10.
2. The strengthening method according to claim 1, wherein the wear-reducing coating layer is formed to have a total thickness of 80 to 160 μm.
3. The strengthening method according to claim 1, wherein the pore diameter of the pores to be strengthened is 6 to 20 mm; and/or the roughness of the surface of the hole wall of the hole to be strengthened is Ra0.2-Ra1.6.
4. The reinforcement method of claim 1, wherein the hole to be reinforced is extrusion-reinforced with an extrusion bar.
5. The strengthening method according to claim 1, wherein the method further comprises the step of forming a transitional wear-reducing coating between the first wear-reducing coating and the second wear-reducing coating, the transitional wear-reducing coating having a coefficient of friction between the coefficients of friction of the first wear-reducing coating and the second wear-reducing coating.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110428424.8A CN112981286B (en) | 2021-04-21 | 2021-04-21 | Hole extrusion strengthening method of aluminum alloy thick plate and lubricant for method |
Applications Claiming Priority (1)
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