CN116463530A - High-speed impact resistant 7xxx series medium-high-strength weldable aluminum alloy and preparation method thereof - Google Patents
High-speed impact resistant 7xxx series medium-high-strength weldable aluminum alloy and preparation method thereof Download PDFInfo
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- 239000006104 solid solution Substances 0.000 claims abstract description 9
- 238000005098 hot rolling Methods 0.000 claims abstract description 7
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- 229910052726 zirconium Inorganic materials 0.000 claims abstract description 4
- 229910052742 iron Inorganic materials 0.000 claims abstract description 3
- 238000005242 forging Methods 0.000 claims description 40
- 230000032683 aging Effects 0.000 claims description 17
- 238000000034 method Methods 0.000 claims description 17
- 238000010438 heat treatment Methods 0.000 claims description 11
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- 238000004321 preservation Methods 0.000 claims description 10
- 239000000243 solution Substances 0.000 claims description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 8
- 238000003723 Smelting Methods 0.000 claims description 6
- 238000000137 annealing Methods 0.000 claims description 6
- 238000010791 quenching Methods 0.000 claims description 5
- 230000000171 quenching effect Effects 0.000 claims description 5
- 238000007599 discharging Methods 0.000 claims description 4
- 238000000465 moulding Methods 0.000 claims description 4
- 230000001681 protective effect Effects 0.000 claims description 4
- 238000005096 rolling process Methods 0.000 claims description 4
- 238000000265 homogenisation Methods 0.000 claims description 2
- 239000000126 substance Substances 0.000 claims description 2
- 238000009966 trimming Methods 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims 2
- 239000011159 matrix material Substances 0.000 abstract description 22
- 229910045601 alloy Inorganic materials 0.000 abstract description 14
- 239000000956 alloy Substances 0.000 abstract description 14
- 239000004033 plastic Substances 0.000 abstract description 14
- 229910052720 vanadium Inorganic materials 0.000 abstract description 8
- 229910052802 copper Inorganic materials 0.000 abstract description 3
- 238000000746 purification Methods 0.000 abstract 1
- 238000005728 strengthening Methods 0.000 description 12
- 238000001514 detection method Methods 0.000 description 11
- 230000007797 corrosion Effects 0.000 description 10
- 238000005260 corrosion Methods 0.000 description 10
- 239000000523 sample Substances 0.000 description 10
- 238000012360 testing method Methods 0.000 description 10
- 239000013078 crystal Substances 0.000 description 9
- 238000003466 welding Methods 0.000 description 8
- 238000010008 shearing Methods 0.000 description 6
- 239000000945 filler Substances 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 238000005275 alloying Methods 0.000 description 3
- 230000035882 stress Effects 0.000 description 3
- 229910052725 zinc Inorganic materials 0.000 description 3
- 229910017706 MgZn Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
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- 229910018571 Al—Zn—Mg Inorganic materials 0.000 description 1
- 238000003917 TEM image Methods 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C21/00—Alloys based on aluminium
- C22C21/10—Alloys based on aluminium with zinc as the next major constituent
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/02—Making non-ferrous alloys by melting
- C22C1/026—Alloys based on aluminium
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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
- C22F1/053—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 of alloys with zinc as the next major constituent
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Abstract
The invention discloses a high-strength weldable aluminum alloy in a 7xxx series for preventing high-speed impact and a preparation method thereof, which are characterized in that: the aluminum alloy comprises the following components in percentage by mass: 4.0 to 7.0 weight percent of Mg:2.0 to 3.0 weight percent, cu:0.05 to 0.40 weight percent, mn:0.10 to 0.40 weight percent, cr is less than or equal to 0.25 weight percent, ti:0.03 to 0.09 weight percent of Zr:0.05 to 0.15 weight percent, Y:0.05 to 0.15 weight percent, V:0.03 to 0.06 weight percent of Fe less than or equal to 0.25 weight percent, si less than or equal to 0.20 weight percent, and the balance of Al and unavoidable impurities. The preparation method comprises casting, integrally forming large-scale structural members or hot-rolling forming planar structural members. The invention relates to a 7xxx series aluminum alloy, which is subjected to dealloying and purification by adding a small amount of Cu, mn, cr, zr, ti, Y, V and other elements, so that the solid solution bond energy of a matrix is enhanced, the viscoplasticity of the alloy is improved, and the plastic processing with large deformation and high-speed impact plastic deformation are realized.
Description
Technical Field
The invention belongs to the technical field of aluminum alloy, and particularly relates to a high-strength weldable aluminum alloy in a 7xxx series for preventing high-speed impact and a preparation method thereof.
Background
With the development of modern aluminum equipment technology, the omnibearing protection and high maneuverability of special vehicles are more and more remarkable, and the special vehicles are aimed at the threats of various bullets, explosives such as mines and the like. The vehicle body of the special vehicle is more emphasized in stability and durability of structural functions on the premise of ensuring a certain protection function. The existing aluminum special vehicle bodies in China are manufactured by adopting filler wire MIG welding connection. The integrally formed car body structure is more reliable and safer than a welded car body in the long-term service and mine explosion threat prevention processes. It has been developed to develop an aluminum alloy for a forged piece or a homogeneous plate integrally formed with a body structure which is medium-high strength, weldable, resistant to high-speed impact and excellent in workability.
Early studies showed that: and in the 7xxx series deformed aluminum alloy, adiabatic shearing is easy to occur in the process of quasi-static large-deformation plastic processing and dynamic high-speed impact to generate a shearing coordination deformation zone, and a damage mode forms microcrack failure along the end part of the deformation zone. Therefore, how to alloy through micro element alloying not only ensures the service performance of the alloy, but also improves the plastic deformation processing capability of the alloy matrix is important.
The invention utilizes the new principle of micro-element alloying to realize that the single-pass deformation amount of the novel 7xxx series medium-high-strength weldable aluminum alloy exceeds 65% in the room-temperature high-speed impact process, and the deformation energy absorption of the matrix structure is coordinated by dynamic recrystallization fine crystals, so that the failure of microcrack formation at the end part of a shear band is greatly reduced, and the plastic deformation processing capacity of the alloy matrix is improved. The developed single-pass large-deformation integrated forming preparation technology is utilized to solve the problem of structural uniformity of large-wall-thickness tissues of the special vehicle body structure.
Disclosure of Invention
The invention aims to provide a high-strength weldable aluminum alloy in a 7xxx series, which can improve the plastic deformation processing capacity of a matrix while ensuring certain strength.
The second technical problem to be solved by the invention is to provide a preparation method of a high-strength weldable aluminum alloy in a 7xxx series for preventing high-speed impact.
The invention solves the first technical problem by adopting the technical scheme that: a high-speed impact resistant 7xxx series medium and high strength weldable aluminum alloy, characterized in that: the aluminum alloy comprises the following components in percentage by mass: 4.0 to 7.0 weight percent of Mg:2.0 to 3.0 weight percent, cu:0.05 to 0.40 weight percent, mn:0.10 to 0.40 weight percent, cr is less than or equal to 0.25 weight percent, ti:0.03 to 0.09 weight percent of Zr:0.05 to 0.15 weight percent, less than or equal to 0.25 weight percent of Fe, less than or equal to 0.20 weight percent of Si, less than or equal to 0.05 weight percent of unavoidable impurities, less than or equal to 0.15 weight percent of total impurities, and the balance of Al.
Preferably, the alloy comprises the following chemical components in percentage by mass: 0.05 to 0.15 weight percent, V:0.03 to 0.06 weight percent.
The invention solves the second technical problem by adopting the technical proposal that: a preparation method of a high-strength weldable aluminum alloy in a 7xxx series for preventing high-speed impact is characterized by comprising the following steps of: the preparation method comprises the following preparation steps:
1) And (3) casting: proportioning according to the required components, keeping the smelting temperature at 720-780 ℃, preserving the heat at 780 ℃ for a certain time, such as 30-60 min, and pouring at 690-720 ℃ to obtain an ingot;
2) Large structural member (outer contour dimension 700-6000 mm. Times.200-2000 mm. Times.200-600 mm) is integrally formed:
(2.1) the aluminum alloy ingot is subjected to homogenization treatment after being subjected to heat preservation for 12 to 36 hours at 470 to 485 ℃;
(2.2) stretching the homogenized ingot by a forging method to obtain a blank; forging the blank into a basic blank of a large-scale structural member by adopting a free forging method, and trimming to obtain a conformal blank with reserved subsequent deformation; extruding the conformal blank by using a die forging method through movement of an upper die and a lower die to fill a die cavity, forging the final shape of the large-sized structural member, and obtaining an integrally formed structural member; the deformation temperature is 400-460 ℃, the final forging temperature is 260-400 ℃, the deformation speed is 10-30 mm/s, and the anvil width ratio is more than or equal to 0.4 (preferably 0.4-0.925);
(2.3) carrying out integral solid solution 475-490 ℃ heat preservation for 0.5-3 h of normal temperature water quenching, performing two-stage aging heat treatment, carrying out first-stage 100-110 ℃ heat preservation for 6-8 h, and second-stage 135-145 ℃ heat preservation for 14-18 h, discharging and air cooling to obtain required structural strength and protective performance, and obtaining the final high-speed impact resistant aluminum alloy large-scale structural member;
or alternatively, the method can be used for processing,
3) Hot rolling and forming a planar structural member:
(3.1) homogenizing annealing: preserving the temperature of the ingot for 12-36 h at 470-485 ℃ for homogenizing treatment;
(3.2) hot rolling: the initial rolling temperature is 400-460 ℃, the total processing rate is more than or equal to 80 percent, and the ingot is processed into a plate after the uniform fire;
(3.3) solution quenching treatment: preserving the temperature of the plate at 475-490 ℃ for 0.5-3 h, and cooling the plate by water at normal temperature;
(3.4) double-stage aging treatment: heating the heating furnace to a required temperature, preserving heat for 6-8 h at the temperature of 100-110 ℃ at the first stage, preserving heat for 14-18 h at the temperature of 135-145 ℃ at the second stage, discharging and cooling in air at normal temperature to obtain the required structural strength and protective performance, and obtaining the final high-speed impact-resistant aluminum alloy planar structural member.
Preferably, the aluminum alloy blank is subjected to forging, stretching or free forging in the step 2.2), and the reduction of 1-2 passes is 15% -35% and large deformation is achieved;
preferably, in the step 3.3), the reduction of 1-2 passes is 15% -35% large deformation;
in the aluminum alloy ingot structure, besides the coarse primary crystal quaternary balance AlZnMg (Cu) phase and the MnFeSi phase, the added micro-alloying effective elements Cu, mn, cr, ti, zr, Y, V are mainly distributed in an atomic form in the ingot, and clusters and precipitated phases are not formed.
The aluminum alloy of the invention adopts the integral molding preparation method of 15% -35% large deformation of the reduction of the middle 1-2 passes, the large wall thickness section structure of the large structural member or the plane structural member is more uniform, even if the thickness section deformation structure grows inconspicuously after the solution is carried out at 475-490 ℃, the grain width of the elongated strip is about 5-20 mu m, and the subgrain width of the elongated strip is about 0.5-2 mu m.
As the microalloying high solid solubility Gao Jianneng Y and V elements are added in the aluminum alloy, the large-sized structural member of the aluminum alloy deforms 15% -35% in 1-2 times of large reduction in the middle of the integral molding preparation method or the alloy plane structural member of the aluminum alloy is subjected to room-temperature high-speed impact deformation, the matrix of the aluminum alloy locally generates streamline plastic shearing deformation, the deformation consisting of countless tiny equiaxed crystals is formed to bring coordinated shearing deformation, the plastic deformation capacity of the matrix is enhanced, and microcrack failure is avoided.
The aluminum alloy of the invention further improves the heat stability and corrosion resistance of an aging strengthening phase of a matrix on the basis of the design of four main elements of Zn, mg, cu and Mn, wherein the aging strengthening phase consists of metastable T ' -AlMgZnCu or T ' -AlMgZnMn phase and eta ' -MgZn 2 The phase composition, the size is 2 nm-10 nm, wherein the metastable T 'phase mass fraction is about 7%, and the metastable eta' phase mass fraction is 1.5% -2.8%.
Compared with the prior art, the invention has the advantages that:
1) The invention relates to a 7xxx series Al-Zn-Mg aluminum alloy, and the key technical means for solving the technical problem of the application is that an alloy matrix has medium and high strength and higher viscoplasticity. The main matrix strength is controlled and contributed by the total amount of Zn and Mg and the Zn/Mg ratio, and a small amount of Cu, mn, cr, ti, zr is added to obtain the auxiliary matrix strengthening effects such as solid solution strengthening, fine crystal strengthening, precipitation strengthening and the like; the micro-composite additive elements Y and V strengthen the solid solution bond energy of the matrix to promote the viscoplasticity of the alloy, thereby realizing plastic processing with large deformation and high-speed impact plastic deformation, ensuring the uniformity of the structure and performance of the thick section and promoting the performance. The aluminum alloy disclosed by the invention controls the content of Cu element, does not form an AlCuY coarse primary crystal phase, and enables the element Y to be maximally solid-dissolved in an as-cast matrix to play a role in solid-solution strengthening and toughening.
2) The alloy of the invention has a very wide thermoplastic processing temperature window, and can still realize 30 to 80 percent of plastic deformation processing at the temperature of 266 ℃ of the billet. The deformation preparation method and the microstructure of the crystal grains and the precipitated phases regulated by the two-stage heat treatment process of the alloy eliminate the adverse effects of coarse crystal and precipitation strengthening on the elastic deformation and plastic deformation of an aluminum alloy matrix, have good filling property, reduce the times of heating and deformation processing by a furnace, and simplify the processing flow.
3) The mechanical properties of the 7xxx series aluminum alloy of the invention are realized by the cooperation of the step 1) and the step 2) or the cooperation of the step 1) and the step 3): tensile strength R m Not less than 410MPa, yield strength R p0.2 Not less than 345MPa, elongation A not less than 7.0%, brinell hardness HBW not less than 120 and impact power KU 2 Not less than 12J; corrosion resistance: the C-shaped ring has no intergranular corrosion, and the stress corrosion resistance loading force is more than or equal to 260MPa; welding performance: the joint strength of ER5356 filler wire MIG welding is more than or equal to 240MPa, and the joint strength of ER5R59 filler wire MIG welding with the same technological parameters is more than or equal to 360MPa; dynamic impact properties: at 1800s -1 Under the strain rate, the impact strength can reach 680MPa, and the static strength is higher than that of the strain rate450MPa is improved by 150 percent.
The 7xxx aluminum alloy has the characteristics of meeting the technical requirements of a special vehicle protection structure in application, namely, the aluminum alloy has the advantages of medium and high strength, high fracture toughness, good impact resistance, good corrosion resistance and good weldability, particularly has excellent plastic workability and remarkable strain rate strengthening effect, and is suitable for processing forge pieces or plates of large-scale complex-section protection structures.
Drawings
FIG. 1 is a diagram showing the distribution of three-dimensional atomic probes 3DATP of atoms of each microalloying element in an aluminum alloy ingot matrix according to the invention;
FIG. 2 is an EBSD image of deformed grains of a matrix after solution treatment of an integrally formed aluminum alloy prepared structural member according to the present invention;
FIG. 3 shows that after the aluminum alloy is deformed by 65% at high speed, the substrate is partially formed into a shear band by fine grains;
FIG. 4 shows TEM images and diffraction spots of the sub-crystal and precipitation-strengthened phases of the alloy matrix after aging treatment of the aluminum alloy of the invention;
FIG. 5 is a stress-strain curve of a high-speed impact of a sample of the sidewall of a large aluminum alloy forging according to example 2 of the present invention;
Detailed Description
The present invention is described in further detail below with reference to examples.
Example 1:7xxx series medium-high strength aluminum alloy preparation integrated large forging car body
The aluminum alloy comprises the following components in percentage by mass: 4.08wt%, mg:2.03wt%, cu:0.125wt%, mn:0.209wt%, cr:0.151wt%, zr:0.083wt%, ti:0.066wt%, Y:0.145wt%, V:0.049wt%, fe:0.138wt%, si:0.046wt% and the balance Al.
The preparation method comprises the following steps:
1) And (3) casting: proportioning according to the required components, smelting at 750-780 ℃, preserving heat and then casting to obtain cast ingots with the specification: 100mm by 1500mm by 2500mm, weighing about 1000kg;
2) Homogenizing and annealing: preserving the heat of the large ingot for 24 hours at 475 ℃;
3) And (3) integrally forming and forging the equal-wall-thickness vehicle body: according to the requirements of the vehicle body structure size of 2m multiplied by 4m multiplied by 0.6m and the vehicle body wall thickness of 18mm, the heating temperature of a large cast ingot with the specification of 100mm multiplied by 1500mm multiplied by 2500mm is kept at 450 ℃ for 10 hours, the large cast ingot is forged into a blank with the specification of 1850mm multiplied by 3500mm multiplied by 56mm, the required vehicle body structure is integrally molded and forged through multiple free forging and one-time blocking die forging at 400-450 ℃, the single-pass reduction of the free forging and the die forging is more than or equal to 20 percent, the anvil width ratio is changed: 0.8-0.925, deformation speed 10-20 mm/s, final forging temperature 330 deg.c and total deformation over 80%. The method comprises the following steps of (1) carrying out nondestructive testing on a forging and pressing bent part of a vehicle body according to the energy portion standard NB/T47013.2-2015, namely, part 2: the ray detection can carry out nondestructive detection on the internal quality, and after the II-level and above damage is met, the method can carry out subsequent processing and heat treatment.
4) Solution treatment: the inside of the vehicle body structure is supported, the whole body is subjected to solid solution treatment, the temperature is kept at 480 ℃ for 2 hours, and the vehicle body structure is subjected to normal-temperature water cooling;
5) And (3) aging process: aging treatment is carried out on the whole body: the first stage is kept at 100-110 ℃ for 6-8 h, and the second stage is kept at 135-145 ℃ for 14-18 h and then air-cooled.
Example 2: integrated V-shaped vehicle bottom protection structure prepared by high-strength aluminum alloy in high-speed impact 7xxx series
The aluminum alloy comprises the following components in percentage by mass: 4.80wt%, mg:2.80wt%, cu:0.199wt%, mn:0.397wt%, cr:0.177wt%, zr:0.150wt%, ti:0.087wt%, fe:0.181wt%, si:0.054wt% and the balance Al.
The preparation method comprises the following steps:
1) And (3) casting: proportioning according to the required components, smelting at 750-780 ℃, preserving heat and then casting to obtain cast ingots with the specification: 300mm by 1200mm by 1900mm, weighing about 1800kg;
2) Homogenizing and annealing: preserving the heat of the large cast ingot for 24 hours at 470 ℃;
3) Integrally forming and forging V-shaped vehicle body and vehicle bottom components with different wall thicknesses: according to the requirements of 2m multiplied by 6m multiplied by 0.5m of the vehicle body structure, 25mm of side wall thickness and 10mm of vehicle bottom thickness, the large cast ingot with the specification of 300mm multiplied by 1200mm multiplied by 1900mm is heated at 450 ℃ and kept for 10h, forged and pressed into a blank with the specification of 85mm multiplied by 1800mm multiplied by 4400mm, the required vehicle body structure is integrally molded and molded by multiple free forging and two closed die forging at 400-450 ℃, the single pass reduction of the free forging and the die forging is more than or equal to 20 percent, the deformation is carried out, the anvil width ratio is 0.66-0.9, the deformation speed is 10 mm/s-20 mm/s, the final forging temperature is 330-380 ℃, and the total deformation is more than 80 percent. The method comprises the following steps of (1) carrying out nondestructive testing on a forging and pressing bent part of a vehicle body according to the energy portion standard NB/T47013.2-2015, namely, part 2: the ray detection can carry out nondestructive detection on the internal quality, and after the II-level and above damage is met, the method can carry out subsequent processing and heat treatment.
4) Solution treatment: the inside of the vehicle body structure is supported, the whole body is subjected to solid solution treatment, the temperature is kept at 480 ℃ for 2 hours, and the vehicle body structure is subjected to normal-temperature water cooling;
5) And (3) aging process: aging treatment is carried out on the whole body: the first stage is kept at 100-110 ℃ for 6-8 h, and the second stage is kept at 135-145 ℃ for 14-18 h and then air-cooled.
Example 3: preparation of high-strength weldable aluminum alloy planar sheet in 7xxx series for preventing high-speed impact
The aluminum alloy comprises the following components in percentage by mass: 6.97wt%, mg:2.88wt%, cu:0.388wt%, mn:0.400wt%, cr:0.102wt%, zr:0.058wt%, ti:0.031wt%, Y:0.075wt%, V:0.060wt%, fe:0.175wt% of Si, 0.028wt% of Al and the balance.
The preparation method comprises the following steps:
1) And (3) casting: proportioning according to the required components, wherein the smelting temperature is 730-780 ℃, casting Fang Zhuding after heat preservation, and the specification is as follows: 300mm by 1200mm by 2000mm;
2) Homogenizing and annealing: preserving the heat of the ingot for 24 hours at 485 ℃;
3) And (3) hot rolling: after the cast ingot is heated to 420 ℃ uniformly, the hot rolling start temperature is 420 ℃, the final rolling temperature is 300-400 ℃, the total deformation is 90%, the maximum single-pass reduction is 20%, and the anvil width ratio is 0.8, so that the hot rolled plate with the thickness of 30mm is obtained.
4) Solution quenching treatment: preserving the temperature of the plate at 475 ℃ for 1h, and cooling the plate by water at normal temperature;
5) Prestretching: straightening and stretching the quenched plate by 1.5% along the rolling direction.
6) And (3) aging process: aging the plate: the first stage is kept at 100-110 ℃ for 6-8 h, and the second stage is kept at 135-145 ℃ for 14-18 h and then air-cooled.
Example 4: integrated forming preparation of 7xxx series medium-high-strength weldable aluminum alloy inducer support forging stock
The aluminum alloy comprises the following components in percentage by mass: 5.99wt%, mg:2.43wt%, cu:0.09wt%, mn:0.374wt%, cr:0.006wt%, zr:0.095wt%, ti:0.041wt%, Y:0.055wt%, V:0.031wt%, fe:0.062wt%, si:0.022wt% and the balance of Al.
The preparation method comprises the following steps:
1) And (3) casting: proportioning according to the required components, wherein the smelting temperature is 730-780 ℃, and casting to obtain round ingots after heat preservation, and the specification is as follows: phi 450mm x 1000mm;
2) Homogenizing and annealing: preserving the heat of the round ingot for 18 hours at 485 ℃;
3) Multi-step hollow cylinder hot die forging: the round ingot is heated to 450 ℃, the die temperature is 450 ℃, the deformation temperature is 400-450 ℃, the deformation speed is 10-20 mm/s, and the round ingot is freely forged: upsetting, squaring, drawing, chamfering, rounding, upsetting to phi 700mm multiplied by 400mm, punching, and die forging to obtain the multi-step hollow cylinder forging blank with required finished product specification, wherein the final forging temperature is 260-335 ℃, the total deformation is 65%, the single-pass maximum reduction is 30%, the anvil width ratio is 0.65, the outer contour is 700mm, and the thickness is 200mm.
4) Solution treatment: preserving the temperature of the forging blank at 480 ℃ for 2 hours, and cooling the forging blank with water at normal temperature;
5) And (3) aging process: and (3) carrying out aging treatment: the first stage is kept at 100-110 ℃ for 6-8 h, and the second stage is kept at 135-145 ℃ for 14-18 h and then air-cooled.
The microalloying effective elements Zn, mg, cu, mn, cr, ti, zr, Y, V added to the aluminum alloy are mainly distributed in an atomic form in an ingot, clusters and precipitated phases are not formed, and various elements are uniformly distributed as shown in the attached figure 1. The aluminum alloy of the invention adopts the integral molding preparation method of 15% -35% large deformation of the reduction of the middle 1-2 passes to make the large-wall thickness section structure of the large-sized structural member or the plane structural member more uniform, even if the large-wall thickness section structure grows inconspicuously after the solid solution at 475-490 ℃, the grain width of the elongated strip is about 5-20 mu m, see figure 2As shown, the number of recrystallized equiaxed grains is very small. The large aluminum alloy structural member deforms 15% -35% in 1-2 times of large reduction in the middle of the integral forming preparation method or the alloy plane structural member deforms at room temperature and high speed in the impact, and the matrix of the aluminum alloy is subjected to streamline plastic shearing deformation locally, so that coordinated shearing deformation is brought by deformation consisting of countless tiny equiaxed crystals, and the aluminum alloy plane structural member is shown in the figure 3. The microstructure of the aluminum alloy comprises a matrix phase and an aging strengthening phase, wherein the width of a subgrain particle of an elongated strip of the matrix is about 0.5-2 mu m, and the length of the subgrain particle is consistent with the processing direction of the aluminum alloy; the ageing strengthening phase is composed of metastable T ' -AlMgZnCu or T ' -AlMgZnMn phase and eta ' -MgZn phase 2 The phase composition, the size is 2 nm-10 nm, the mass fraction of metastable T 'phase is about 7%, the mass fraction of metastable eta' phase is 1.5% -2.8%, see figure 4, the diffraction spots show matrix superlattice Al 3 The (Zr, Y) nanophase will strengthen the alloy matrix.
The following performance tests were performed on the examples:
sample processing and detection testing for tensile test are carried out according to national standard GB/T16865-2013, sample processing and detection testing for Brinell hardness are carried out according to national standard GB/T231.1-2009, and KU is carried out according to national standard GB/T229-2020 2 The method comprises the steps of performing impact function sample processing and detection testing, performing sample processing and detection testing for intergranular corrosion testing according to national standard GB/T7998-2005, performing sample processing and detection testing for C-shaped ring stress corrosion testing according to national standard GB/T22640-2008, performing sample processing and detection testing for flat welding seam tensile testing according to national standard GB/T2651-2008, and performing sample processing and detection testing for room temperature high speed impact testing according to national standard GB/T34108-2017. The results of the above tests are shown in Table 2.
FIG. 5 is a stress-strain curve of a large forging sidewall sample according to example 2 of the present invention subjected to high-speed impact at different strain rates, showing that the aluminum alloy of the present invention exhibits positive strain rate strengthening effect, and the impact strength is improved from quasi-static 450MPa to 1800s -1 At a strain rate of 680MPa. When the strain rate reaches 3000s -1 When the material is used, the morphology is damaged after detonation, and the dynamic impact resistance can reach more than 1200 MPa.
From the above examples, it was demonstrated that the mechanical properties of the 7xxx series aluminum alloys of the invention: tensile strength R m Not less than 410MPa, yield strength R p0.2 Not less than 345MPa, elongation A not less than 7.0%, brinell hardness HBW not less than 120 and impact power KU 2 Not less than 12J; corrosion resistance: the C-shaped ring has no intergranular corrosion, and the stress corrosion resistance loading force is more than or equal to 260MPa; welding performance: the joint strength of ER5356 filler wire MIG welding is more than or equal to 240MPa, and the joint strength of ER5R59 filler wire MIG welding with the same technological parameters is more than or equal to 360MPa; dynamic impact properties: at 1800s -1 Under the strain rate, the impact strength can reach 680MPa, and is improved by 150% compared with the static strength of 450 MPa.
TABLE 1 Components/wt% of the examples of the invention
Table 2 properties of inventive examples and comparative examples
Claims (5)
1. A high-speed impact resistant 7xxx series medium and high strength weldable aluminum alloy, characterized in that: the aluminum alloy comprises the following components in percentage by mass: 4.0 to 7.0 weight percent of Mg:2.0 to 3.0 weight percent, cu:0.05 to 0.40 weight percent, mn:0.10 to 0.40 weight percent, cr is less than or equal to 0.25 weight percent, ti:0.03 to 0.09 weight percent of Zr:0.05 to 0.15 weight percent, less than or equal to 0.25 weight percent of Fe, less than or equal to 0.20 weight percent of Si, less than or equal to 0.05 weight percent of unavoidable impurities, less than or equal to 0.15 weight percent of total impurities, and the balance of Al.
2. A high-impact 7xxx series medium-high strength weldable aluminum alloy of claim 1, wherein: the aluminum alloy comprises the following chemical components in percentage by mass: 0.05 to 0.15 weight percent, V:0.03 to 0.06 weight percent.
3. A method for preparing a high-strength weldable aluminum alloy in a high-speed impact-resistant 7xxx series according to claim 1 and claim 2, which is characterized by comprising the following steps: the preparation method comprises the following preparation steps:
1) And (3) casting: proportioning according to the required components, keeping the smelting temperature at 720-780 ℃, preserving the heat at 780 ℃ for 30-60 min, and pouring at 690-720 ℃ to obtain an ingot;
2) Integral molding of large-scale structural parts:
(2.1) the aluminum alloy ingot is subjected to homogenization treatment after being subjected to heat preservation for 12 to 36 hours at 470 to 485 ℃;
(2.2) stretching the homogenized ingot by a forging method to obtain a blank; forging the blank into a basic blank of a large-scale structural member by adopting a free forging method, and trimming to obtain a conformal blank with reserved subsequent deformation; extruding the conformal blank by using a die forging method through movement of an upper die and a lower die to fill a die cavity, forging the final shape of the large-sized structural member, and obtaining an integrally formed structural member; the deformation temperature is 400-460 ℃, the final forging temperature is 260-400 ℃, the deformation speed is 10-30 mm/s, and the anvil width ratio is more than or equal to 0.4;
(2.3) carrying out integral solid solution 475-490 ℃ heat preservation for 0.5-3 h, normal temperature water quenching and two-stage aging heat treatment on the formed structural member, wherein the first stage is 100-110 ℃ heat preservation for 6-8 h, the second stage is 135-145 ℃ heat preservation for 14-18 h, discharging and air cooling to obtain required structural strength and protective performance, and obtaining the final high-speed impact resistant aluminum alloy large structural member;
or is
3) Hot rolling and forming a planar structural member:
(3.1) homogenizing annealing: preserving the temperature of the ingot for 12-30 hours at 470-485 ℃ for homogenizing treatment;
(3.2) hot rolling: the initial rolling temperature is 400-460 ℃, the total processing rate is more than or equal to 80 percent, and the ingot is processed into a plate after the uniform fire;
(3.3) solution quenching treatment: preserving the temperature of the plate at 475-490 ℃ for 0.5-3 h, and cooling the plate by water at normal temperature;
(3.4) double-stage aging treatment: heating the heating furnace to a required temperature, preserving heat for 6-8 h at the temperature of 100-110 ℃ at the first stage, preserving heat for 14-18 h at the temperature of 135-145 ℃ at the second stage, discharging and cooling in air at normal temperature to obtain the required structural strength and protective performance, and obtaining the final high-speed impact-resistant aluminum alloy planar structural member.
4. The integrally formed manufacturing method as claimed in claim 3, wherein: the aluminum alloy blank is subjected to forging, stretching or free forging in the step 2.2), and the reduction of 1-2 passes is 15% -35% and large deformation is achieved.
5. The integrally formed manufacturing method as claimed in claim 3, wherein: in the step 3.2), the reduction of 1-2 passes is 15% -35% and the deformation is large.
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