CN115261750A - Aging heat treatment method of 7-series aluminum alloy - Google Patents
Aging heat treatment method of 7-series aluminum alloy Download PDFInfo
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- 229910000838 Al alloy Inorganic materials 0.000 title claims abstract description 119
- 230000032683 aging Effects 0.000 title claims abstract description 99
- 238000010438 heat treatment Methods 0.000 title claims abstract description 91
- 238000000034 method Methods 0.000 title claims abstract description 42
- 239000000956 alloy Substances 0.000 claims abstract description 107
- 238000010791 quenching Methods 0.000 claims abstract description 18
- 230000000171 quenching effect Effects 0.000 claims abstract description 18
- 239000006104 solid solution Substances 0.000 claims abstract description 10
- 238000001816 cooling Methods 0.000 claims abstract description 8
- 238000011282 treatment Methods 0.000 claims description 24
- 239000003595 mist Substances 0.000 claims description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 2
- 238000010079 rubber tapping Methods 0.000 claims 1
- 230000007797 corrosion Effects 0.000 abstract description 29
- 238000005260 corrosion Methods 0.000 abstract description 29
- 230000008569 process Effects 0.000 abstract description 19
- 239000000463 material Substances 0.000 abstract description 18
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 abstract description 3
- 229910052782 aluminium Inorganic materials 0.000 abstract description 3
- 238000007599 discharging Methods 0.000 abstract description 2
- 238000004519 manufacturing process Methods 0.000 abstract description 2
- 229910045601 alloy Inorganic materials 0.000 description 18
- 230000006911 nucleation Effects 0.000 description 16
- 238000010899 nucleation Methods 0.000 description 16
- 239000013078 crystal Substances 0.000 description 14
- 230000000052 comparative effect Effects 0.000 description 11
- 238000001556 precipitation Methods 0.000 description 11
- 229910052725 zinc Inorganic materials 0.000 description 11
- 238000000137 annealing Methods 0.000 description 10
- 238000005266 casting Methods 0.000 description 10
- 229910052804 chromium Inorganic materials 0.000 description 10
- 238000001125 extrusion Methods 0.000 description 10
- 229910052742 iron Inorganic materials 0.000 description 10
- 229910052748 manganese Inorganic materials 0.000 description 10
- 229910052802 copper Inorganic materials 0.000 description 8
- 229910052726 zirconium Inorganic materials 0.000 description 8
- 238000009826 distribution Methods 0.000 description 7
- 239000011159 matrix material Substances 0.000 description 5
- 239000002244 precipitate Substances 0.000 description 5
- 230000009286 beneficial effect Effects 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000005728 strengthening Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 230000001133 acceleration Effects 0.000 description 2
- 230000033228 biological regulation Effects 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 238000005242 forging Methods 0.000 description 2
- 230000004927 fusion Effects 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000004321 preservation Methods 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 230000035882 stress Effects 0.000 description 2
- 229910017708 MgZn2 Inorganic materials 0.000 description 1
- 229910009369 Zn Mg Inorganic materials 0.000 description 1
- 229910007573 Zn-Mg Inorganic materials 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000003574 free electron Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 238000005036 potential barrier Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000004901 spalling Methods 0.000 description 1
- 238000007725 thermal activation Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- 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
- 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
- C22F1/002—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working by rapid cooling or quenching; cooling agents used therefor
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Abstract
The invention discloses an aging heat treatment method suitable for 7-series aluminum alloy, which comprises the following steps: the aluminum alloy material after solid solution or on-line quenching is stretched and straightened at the elongation of 1% -3%, the stretched aluminum alloy material is naturally parked for 0-168h at room temperature after being sawn according to a fixed length, and then the material is heated at a heating rate V from room temperature or a temperature higher than the room temperature in an aging furnace 1 Heating to 130-150 deg.C, and heating at a heating rate V 2 Continuously heating to 170-220 deg.C, stopping heating, discharging, and cooling to room temperature. The present invention improves the conventional aluminum material heat treatment process, the prepared aluminum alloy material has high strength, excellent corrosion resistance, short production flow and simple and convenient operation.
Description
Technical Field
The invention belongs to the field of aluminum alloy heat treatment, and particularly relates to an aging heat treatment method of a 7-series aluminum alloy.
Background
The common aging system of the 7 series aluminum alloy material comprises the following steps: (1) constant temperature single stage aging: for example, the T6 single-stage peak aging of 120 ℃ multiplied by 96h commonly used for 7020 aluminum alloy, the T6 single-stage peak aging of 120 ℃ multiplied by 24h commonly used for 7050 aluminum alloy and the like, the single-stage T6 peak aging aims to form MgZn2 aging strengthening phases with small size and large number density in crystal, and at the moment, the strength of the alloy is the highest, but precipitated phases on crystal boundaries are continuously distributed, and the corrosion resistance of the alloy is poor. Further prolonging the heat preservation time to an overaging state, the precipitation phase in the crystal grows and coarsens, the crystal boundary becomes discontinuous gradually, and the strength of the alloy is reduced at the moment, but the corrosion resistance is improved. (2) Two-stage aging: in order to solve the problems of long time for reaching peak aging and over-aging by single-stage aging and poor corrosion resistance, the American aluminum industry develops a T73, T76 and T74 two-stage aging system, and the strength of the alloy in the process is reduced by 9-15 percent compared with the single-stage peak aging T6, but the stress corrosion resistance and the spalling corrosion resistance are improved. The process generally comprises low-temperature pre-aging and high-temperature aging, and aims to precipitate phase nucleation and form small-size precipitated phase in the low-temperature heat preservation process, and then perform second constant-temperature aging at high temperature to allow the precipitated phase to grow. Compared with single-stage aging, the double-stage aging shortens the time for reaching peak aging and overaging, the grain boundary precipitated phase distribution of the material becomes discontinuous, and the corrosion resistance is improved. However, since the second stage temperature is generally high, a portion of the GP zones and the small sized precipitates generally undergo partial recovery at the beginning of the second stage exposure, dissolve into the matrix, and inevitably cause loss of the precipitates and strength. Meanwhile, although the two-stage overaging greatly improves the time for overaging, the alloy is easy to coarsen, and the performance of the alloy is reduced too fast. (3) Retrogression heat treatment and its improvement (tertiary aging): namely, pre-aging is firstly carried out, then regression treatment is carried out, and finally re-aging is carried out. The alloy subjected to regression and reaging treatment can obtain the strength of T6 level and the corrosion resistance of T7 overaging level, and the high strength and the high corrosion resistance are achieved. However, the process needs a short regression treatment at high temperature, has operation difficulty for thicker materials and larger forgings, and is mainly used for 7-series aluminum alloy for aviation and aerospace at present. The non-isothermal process is introduced into the regression treatment, so that the problems of high temperature, short time and inconvenient operation of the traditional regression treatment are improved to a certain extent, but the operation process is still more complicated.
According to classical nucleation theory, the nucleation driving force and the growth rate of the precipitated phase are related to the concentration of solute atoms in the current matrix. In the isothermal aging process, the current solute concentration in the matrix is continuously reduced along with the aging, and the nucleation driving force and the growth rate of a precipitated phase are gradually reduced. In the isothermal aging process, at a certain stage of the nucleation process, the nucleation rate is gradually reduced and the difficulty is increased along with the aging. The nucleation process is a thermal activation process, and in the conventional isothermal aging process, such as single-stage T6 peak aging and single-stage T73 overaging, al-Zn-Mg alloy is generally aged at a constant temperature of 90-120 ℃, so that the precipitation phase nucleation and growth are inefficient.
In a two stage aging such as T73, recovery occurs early in the second stage exposure to high temperatures, and a portion of the GP zones and small sized precipitates will dissolve into the matrix, inevitably resulting in loss of precipitates and strength. Meanwhile, although the two-stage overaging greatly improves the arrival time of the overaging, the alloy is easier to coarsen.
U.S. Patent publication No. US Patent 3856584 proposes a three stage aging process including pre-aging, regression treatment, and re-aging. The alloy after the regression and re-aging treatment can obtain the strength of T6 level and the corrosion resistance of T7 overaging level, and realizes the combination of high strength and high corrosion resistance. However, this process requires a short regression process at high temperatures, and it is difficult to ensure consistent surface and core properties for thicker materials and larger forgings.
The Chinese patent with publication number CN114381676A discloses a method for efficiently preparing high-strength 7-series aluminum alloy, which mainly carries out two-stage aging treatment on the 7-series aluminum alloy under the condition of a pulsed magnetic field, wherein electromagnetic energy provided by the pulsed magnetic field is absorbed by atoms and atom clusters of the 7-series aluminum alloy in the method, high-energy excitation of aluminum alloy atoms or atom clusters is realized, potential barriers are overcome, nucleation is realized, the aging precipitation of supersaturated solid solution is accelerated, and high strength can be obtained. However, the process has high requirements on equipment, and cannot meet the requirement of cooperative regulation of different microstructures and morphologies of the grain interior and the grain boundary of the alloy.
Chinese patent with publication number CN109457152A in 2018 discloses a 7-series aluminum alloy aging process of non-isothermal regression re-aging, which is characterized in that an aluminum alloy material subjected to solution quenching is heated to 140-210 ℃ at a speed of 30-40 ℃/h, then is rapidly cooled to 40-80 ℃, and is subjected to re-aging treatment at 120 ℃ for 4-30 h. The process firstly utilizes high-temperature pre-precipitation of continuous heating to promote discontinuous distribution of a grain boundary precipitated phase, then rapidly cools and retains the discontinuous distribution state of the grain boundary, and finally carries out low-temperature conventional aging to promote precipitation of an intra-grain precipitated phase.
At present, the conventional aging process of the 7-series aluminum alloy is generally single-stage aging or double-stage aging with low temperature and high temperature, and the aging process generally improves the corrosion resistance by sacrificing certain strength and achieving overaging. The regression re-aging or the three-stage aging has a short high-temperature regression treatment, so the temperature is high, the time is short, the requirement on equipment is high, the operation convenience is poor, and the performance unevenness is easy to occur on thicker materials. Therefore, under the existing traditional aging process, the strength and the corrosion resistance of the material are difficult to obtain, the performance of the material cannot be fully exerted, and the problems of multiple operation steps, complex process and high requirement on equipment exist.
Disclosure of Invention
The invention aims to provide an aging heat treatment method of a 7-series aluminum alloy material, which overcomes the contradiction that the high strength and the high corrosion resistance of the existing 7-series aluminum alloy can not be obtained simultaneously, solves the problems of high requirement on equipment, complex process, inconvenient operation and insufficient performance of material in the prior aging process. The invention can well solve the problems, the novel method is simple and convenient to operate, has low requirements on equipment and low comprehensive cost, and the prepared 7-series aluminum alloy material has high strength and good corrosion resistance and meets the use requirements.
Therefore, the invention adopts the following technical scheme:
the aging heat treatment method of the 7 series aluminum alloy material comprises the following steps:
carrying out solid solution or online quenching treatment on the 7 series aluminum alloy material to be processed;
then, stretching the 7 series aluminum alloy material at the elongation of 1-3%;
sawing the stretched 7-series aluminum alloy material according to a set length, and naturally standing at room temperature for 0-168h, wherein the length is more than 0;
then the 7 series aluminum alloy material is put into an aging furnace, and the heating rate V is carried out in the aging furnace 1 Heating to 130-150 deg.C from the current starting temperature, and heating at a heating rate V 2 And (3) continuing heating to 170-220 ℃, stopping heating, taking out the 7 series aluminum alloy material from the aging furnace, and cooling to room temperature to finish the treatment of the 7 series aluminum alloy material.
Preferably, the stretching treatment is performed at normal temperature, and the elongation is 2% -3%.
Preferably, the room-temperature natural standing time is 0-72h and is more than 0.
Preferably, the heating rate V is 1 ＜V 2 。
Preferably, the heating rate is 5 ℃ to V 1 ≤20℃/h。
Preferably, the heating rate is 5 ℃ to V 1 ≤10℃/h。
Preferably, the heating rate is 20 ℃ to V 2 ≤40℃/h。
Preferably, the 7-series aluminum alloy is heated in an aging furnace at a heating rate V 1 The starting temperature for starting heating is room temperature, or a certain temperature higher than room temperature and the certain temperature is less than 100 ℃.
Preferably, the aluminium alloy is heated in an ageing furnace at a heating rate V 1 From a temperature above room temperatureAt the start of heating, the temperature did not exceed 80 ℃.
Preferably, the 7-series aluminum alloy material is cooled naturally, or by air cooling or water mist cooling after being discharged.
Preferably, the temperature of the solid solution or online quenching is 450-550 ℃.
The application of the invention has the following beneficial technical effects:
the 7-series aluminum alloy material is subjected to solid solution or quenching treatment, and then is subjected to stretching with the elongation of 1% -3% at normal temperature, so that high-volume-fraction dislocation can be formed in the material, and more nucleation points are provided for subsequent heterogeneous precipitation nucleation. Meanwhile, the inventor designs a natural aging program of short-time room temperature standing after normal temperature stretching, can promote the formation of Zn and Mg atomic clusters under the natural aging condition, and is favorable for starting from a certain temperature higher than the room temperature when the subsequent heating and aging are carried out at the heating rate V1 because the material has certain initial strength, and the heating rate lower than the temperature can not be required. This greatly shortens the total time of the invention, thus saving energy consumption.
The invention designs that the temperature is increased to different temperatures in an aging furnace at two different rates, the first heating rate is less than the second heating rate, and the heating rate is V 1 When heating is carried out, because the heating rate is low, the method is beneficial to full nucleation at low temperature, and the coarsening efficiency of the precipitated phase is low, so that the alloy forms a large number of nucleation points and small-sized precipitated phases in the crystal. Then heating at a heating rate V 2 The material is continuously heated to a higher temperature, because of the acceleration of the heating rate, the growth of the nucleation points in the crystal and the small-size precipitated phases occurs, but because of the acceleration of the heating rate, the exposure time of the material at the high temperature is short, although the precipitated phases are long and large, the coarsening degree is small, and the mechanical property of the material is higher than that of the material with the ordinary isothermal aging T6. At the same time, because the energy at the grain boundaries is higher than that in the crystal, the morphology of the precipitated phase at the grain boundaries rapidly undergoes a transition from absent to present, from continuous to discontinuous distribution, and the width of the precipitate-free zone is not as wide as T73 or other outdated bands due to the short exposure time at high temperaturesThe effect is too wide, so that the excellent corrosion resistance is obtained, and the combination of high strength and high corrosion resistance is realized.
When the aluminum alloy is subjected to aging heat treatment, normal-temperature stretching, room-temperature standing and variable-rate heating are comprehensively applied, dislocation strengthening and non-uniform nucleation are effectively utilized, the whole process is consistent with the production process of aluminum profiles, the operation is convenient, the requirement on equipment is not high, the total aging time is shortened, and the energy conservation and consumption reduction are realized.
The method provided by the invention is used for preparing the aluminum alloy, the alloy crystal is internally provided with a mature aging precipitation phase with high volume fraction but without serious coarsening, the precipitation phase on the crystal boundary is discontinuously distributed, the width of a precipitation-free strip is moderate, the cooperative regulation and control of the crystal internal precipitation phase and the crystal boundary precipitation phase are realized, the strength of the prepared alloy exceeds that of a T6 aluminum alloy material, and the corrosion resistance reaches or is superior to that of a T73 aluminum alloy material.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to specific embodiments below. It is to be understood that the following examples are illustrative only and are not to be construed as limiting the scope of the invention, which is intended to be covered by the appended claims.
Example 1
A7 series aluminum alloy material comprises the following components in percentage by mass: 4.0 to 5.0 percent of Zn, 1.0 to 2.0 percent of Mg, less than 0.3 percent of Cu, 0.2 to 0.7 percent of Mn, less than 0.3 percent of Cr, less than 0.35 percent of Fe, less than 0.30 percent of Si, less than 0.25 percent of Zr, and less than 0.2 percent of Ti, and meets the component range of 7N01 in the national standard JIS H4100-2015.
The 7-series aluminum alloy material prepared according to the components and the weight percentage sequentially undergoes fusion casting, homogenizing annealing and extrusion, the on-line quenching temperature is 520 ℃, the tensile rate at room temperature is 2 percent, the material is parked for 72 hours at room temperature after being sawed and is put into an aging furnace, the starting temperature is set to be 80 ℃, the temperature is increased to 80 ℃ within 10min in the aging furnace at any heating rate, and then V is used 1 Heating to 145 ℃ at a heating rate of 5 ℃/h, and then heating atV 2 Continuously heating to 190 ℃ at the heating rate of 20 ℃/h, stopping heating, discharging, and naturally cooling to room temperature.
Example 2
A7-series aluminum alloy material comprises the following components in percentage by mass: 4.0 to 5.0 percent of Zn, 1.0 to 2.0 percent of Mg, less than 0.3 percent of Cu, 0.2 to 0.7 percent of Mn, less than 0.3 percent of Cr, less than 0.35 percent of Fe, less than 0.30 percent of Si, less than 0.25 percent of Zr, and less than 0.2 percent of Ti, and meets the component range of 7N01 in the national standard JIS H4100-2015.
The aluminum alloy material prepared according to the components and the weight percentage is subjected to casting, homogenizing annealing and extrusion in sequence, the on-line quenching temperature is 530 ℃, the tensile rate is 2% at room temperature, the aluminum alloy material is parked for 72 hours at room temperature after being sawed, the aluminum alloy material is heated to 145 ℃ from the room temperature at the heating rate of 5 ℃/h in an aging furnace, then the aluminum alloy material is stopped from being heated to 190 ℃ at the heating rate of 20 ℃/h, and then the aluminum alloy material is taken out of the furnace and is naturally cooled to the room temperature.
Example 3
A7-series aluminum alloy material comprises the following components in percentage by mass: 5.7 to 6.7 percent of Zn, 1.9 to 2.6 percent of Mg, 2.0 to 2.6 percent of Cu2, less than 0.1 percent of Mn, less than 0.04 percent of Cr, less than 0.15 percent of Fe, less than 0.12 percent of Si, 0.08 to 0.15 percent of Zr0.06 percent of Ti, and meets the component range of 7050 in the national standard GB/T3180-2008.
The aluminum alloy material prepared according to the components and the weight percentage is subjected to fusion casting, homogenizing annealing and extrusion in sequence, the solid solution temperature is 460 ℃, the room-temperature elongation is 2.2%, the aluminum alloy material is parked for 24 hours at room temperature after being sawed, the aluminum alloy material is heated to 80 ℃ in an aging furnace for 10min, then the aluminum alloy material is heated to 150 ℃ at the heating rate of 5 ℃/h, then the aluminum alloy material is continuously heated to 210 ℃ at the heating rate of 20 ℃/h, and then the aluminum alloy material is stopped from being heated and discharged, and is naturally cooled to room temperature.
Comparative example 1
A7 series aluminum alloy material comprises the following components in percentage by mass: 4.0 to 5.0 percent of Zn, 1.0 to 2.0 percent of Mg, less than 0.3 percent of Cu, 0.2 to 0.7 percent of Mn, less than 0.3 percent of Cr, less than 0.35 percent of Fe, less than 0.30 percent of Si, less than 0.25 percent of Zr, and less than 0.2 percent of Ti, which meets the component range of 7N01 in the national standard JIS H4100-2015.
The aluminum alloy materials prepared according to the components and the weight percentage are sequentially subjected to casting, homogenizing annealing and extrusion, the online quenching temperature is 520 ℃, the aluminum alloy materials are not subjected to stretching treatment and standing after quenching, the aluminum alloy materials are immediately placed into an aging furnace for 10min, the temperature is raised to 80 ℃, then the aluminum alloy materials are heated to 145 ℃ at the heating rate of 5 ℃/h, then the aluminum alloy materials are continuously heated to 190 ℃ at the heating rate of 20 ℃/h, then the aluminum alloy materials are stopped from being heated and discharged, and the aluminum alloy materials are naturally cooled to the room temperature.
Comparative example 2
A7 series aluminum alloy material comprises the following components in percentage by mass: 4.0 to 5.0 percent of Zn, 1.0 to 2.0 percent of Mg, less than 0.3 percent of Cu, 0.2 to 0.7 percent of Mn, less than 0.3 percent of Cr, less than 0.35 percent of Fe, less than 0.30 percent of Si, less than 0.25 percent of Zr, less than 0.2 percent of Ti, and meets the component range of 7N01 in JIS H4100-2015.
The aluminum alloy material prepared according to the components and the weight percentage is subjected to casting, homogenizing annealing and extrusion in sequence, the on-line quenching temperature is 530 ℃, the stretching is not carried out, the aluminum alloy material is parked for 72 hours at the room temperature after the saw cutting, the aluminum alloy material is heated to 80 ℃ in an aging furnace for 10min, then is heated to 145 ℃ at the heating rate of 5 ℃/h, then is continuously heated to 190 ℃ at the heating rate of 20 ℃/h, is stopped from being heated and taken out of the furnace, and is naturally cooled to the room temperature.
Comparative example 3
A7-series aluminum alloy material comprises the following chemical components in percentage by mass: 4.0 to 5.0 percent of Zn, 1.0 to 2.0 percent of Mg, less than 0.3 percent of Cu, 0.2 to 0.7 percent of Mn, less than 0.3 percent of Cr, less than 0.35 percent of Fe, less than 0.30 percent of Si, less than 0.25 percent of Zr, and less than 0.2 percent of Ti, which meets the component range of 7N01 in JIS H4100-2015.
The aluminum alloy materials prepared according to the components and the weight percentage are subjected to casting, homogenizing annealing and extrusion in sequence, the online quenching temperature is 540 ℃, the aluminum alloy materials are stretched with the stretching amount of 2% at the room temperature without being parked, the aluminum alloy materials are immediately heated to 80 ℃ in an aging furnace for 10min and then heated to 145 ℃ at the heating rate of 5 ℃/h, then the aluminum alloy materials are continuously heated to 190 ℃ at the heating rate of 20 ℃/h, and then the aluminum alloy materials are stopped from being heated and discharged, and are naturally cooled to the room temperature.
Comparative example 4
A7 series aluminum alloy material comprises the following components in percentage by mass: 4.0 to 5.0 percent of Zn, 1.0 to 2.0 percent of Mg, less than 0.3 percent of Cu, 0.2 to 0.7 percent of Mn, less than 0.3 percent of Cr, less than 0.35 percent of Fe, less than 0.30 percent of Si, less than 0.25 percent of Zr, and less than 0.2 percent of Ti, and meets the component range of 7N01 in the national standard JIS H4100-2015.
The aluminum alloy material prepared according to the components and the weight percentage is subjected to casting, homogenizing annealing and extrusion in sequence, the on-line quenching temperature is 520 ℃, the tensile quantity at room temperature is 2%, the aluminum alloy material is parked at the room temperature for 72h after being sawed, the aluminum alloy material is heated to 80 ℃ in an aging furnace for 10min, then the aluminum alloy material is heated to 190 ℃ at the heating rate of 5 ℃/h, then the aluminum alloy material is stopped to be heated and discharged, and the aluminum alloy material is naturally cooled to the room temperature and is heated only once.
Comparative example 5
A7-series aluminum alloy material comprises the following components in percentage by mass: 4.0 to 5.0 percent of Zn, 1.0 to 2.0 percent of Mg, less than 0.3 percent of Cu, 0.2 to 0.7 percent of Mn, less than 0.3 percent of Cr, less than 0.35 percent of Fe, less than 0.30 percent of Si, less than 0.25 percent of Zr, and less than 0.2 percent of Ti, which meets the component range of 7N01 in the national standard JIS H4100-2015.
The aluminum alloy material prepared according to the components and the weight percentage is subjected to casting, homogenizing annealing and extrusion in sequence, the on-line quenching temperature is 530 ℃, the tensile quantity at room temperature is 2%, the aluminum alloy material is parked at the room temperature for 72h after being sawed, the aluminum alloy material is heated to 80 ℃ in an aging furnace for 10min, then the aluminum alloy material is heated to 190 ℃ at the heating rate of 20 ℃/h, then the aluminum alloy material is stopped to be heated and discharged, and the aluminum alloy material is naturally cooled to the room temperature, and is heated only once.
Comparative example 6
A7-series aluminum alloy material comprises the following chemical components in percentage by mass: 4.0 to 5.0 percent of Zn, 1.0 to 2.0 percent of Mg, less than 0.3 percent of Cu, 0.2 to 0.7 percent of Mn, less than 0.3 percent of Cr, less than 0.35 percent of Fe, less than 0.30 percent of Si, less than 0.25 percent of Zr, less than 0.2 percent of Ti, and meets the component range of 7N01 in JIS H4100-2015.
The aluminum alloy material prepared according to the components and the weight percentage is subjected to casting, homogenizing annealing and extrusion in sequence, the online quenching temperature is 540 ℃, and the aluminum alloy material is immediately placed into an aging furnace after quenching for T6 and T73 aging according to the traditional aging process (T6: 90 ℃ is multiplied by 12h +169 ℃ is multiplied by 5h T73. No stretching treatment was performed.
Comparative example 7
A7 series aluminum alloy material comprises the following chemical components in percentage by mass: 5.7 to 6.7 percent of Zn, 1.9 to 2.6 percent of Mg, 2.0 to 2.6 percent of Cu2, less than 0.1 percent of Mn, less than 0.04 percent of Cr, less than 0.15 percent of Fe, less than 0.12 percent of Si, 0.08 to 0.15 percent of Zr0.06 percent of Ti, and meets the component range of 7050 in the national standard GB/T3180-2008.
The aluminum alloy material prepared according to the components and the weight percentage is subjected to casting, homogenizing annealing and extrusion in sequence, the solid solution temperature is 450-460 ℃, and the quenched aluminum alloy material is immediately placed into an aging furnace to be aged according to the traditional aging process at T6 and T73 (T6: 120 ℃ x 24h, T73. No stretching treatment was performed.
The 7-series aluminum alloys treated in examples 1 to 3 and comparative examples 1 to 7 were subjected to performance tests. At least 3 replicates were taken for each set of states.
In the case of the 7-series aluminum alloy having the same composition, the electric conductivity may reflect the progress of aging to some extent. As the aging progresses, solute atoms are desolventized from the matrix, and an aging precipitation phase is formed, so that the electric conductivity is increased. Along with the deepening of the aging process, the size of an aging strengthening phase in the crystal is gradually increased, a local strain field is eliminated, the size of a grain boundary precipitated phase is gradually increased, the appearance of the grain boundary is changed from continuous distribution to discontinuous distribution, the scattering effect on free electrons is reduced, and the electric conductivity is improved. The change of the grain boundary in the crystal is directly related to the corrosion resistance, and the transformation of the grain boundary precipitated phase from continuous distribution to discontinuous is beneficial to improving the corrosion resistance of the 7-series aluminum alloy, such as intercrystalline corrosion resistance, stress corrosion resistance and the like. Many studies have shown that the higher the conductivity, the better the corrosion resistance of the 7-series aluminum alloy without changing the composition. Therefore, the conductivity is used as an indirect measure of the corrosion resistance of the alloy.
Table 1 shows the mechanical properties and electrical conductivity of 7N01 aluminum alloy treated by different aging processes. It can be seen that the alloys treated in examples 1 and 2 exhibit both high strength and high electrical conductivity. As compared with the conventional peak aging process T6 in comparative example 6, the yield strength and tensile strength of examples 1 and 2, which comprehensively employed the tensile pre-strain, room temperature stand and variable rate heating treatments, were improved by 4 to 6%, respectively, the elongation was improved from 13.4% to 15.4% and 15.6%, respectively, and the conductivity was improved from 37.2% IACS to 40.3% IACS and 40.4% IACS, respectively. The elongation after fracture of examples 1 and 2 was maintained at a comparable level, the conductivity was increased from 39.4% iacs to 40.3% iacs and 40.4% iacs, respectively, and the yield strength and tensile strength were increased by 14.6-16.5%, respectively, as compared to the conventional overaging T73 process. Therefore, the alloy treated by the method can achieve the combination of high strength and high corrosion resistance.
As can be seen from the examples 1-2 and the comparative examples 1-3, before the variable-rate continuous heating aging is carried out, the tensile pre-strain and the room-temperature standing are comprehensively adopted, so that the mechanical property and the corrosion resistance of the material can be further improved to a certain extent, and the additive effect can be achieved.
As can be seen from examples 1-2 and comparative examples 4-5, the strength and conductivity were low using the constant rate continuous heating process, either at a low rate of 5 deg.C/h or at a high rate of 20 deg.C/h. This is because the exposure time at high temperature is long at a low rate, and the coarsening of the intragranular precipitate phase is severe. The retention time at the low temperature stage is short at a high rate, and the precipitated phase in the crystal is insufficient in nucleation and growth, thereby resulting in lower strength.
TABLE 1 Performance of 7N01 aluminum alloys treated by different aging processes
Table 2 is a comparison of the properties of 7050 aluminum alloy treated in accordance with the present invention and conventional techniques, it can be seen that, after the treatment in accordance with the present invention, the yield strength and tensile strength of 7050 aluminum alloy were respectively improved by 17.8MPa and 21.9MPa, as compared to the conventional T6 temper, the elongation after breakage was increased from 9.2% to 11.6%, and the conductivity was increased from 38.1% IACS to 38.9% IACS. Compared with the traditional double-stage aging T73, the alloy treated by the invention has the advantages that the yield strength and the tensile strength are respectively improved by 54.5MPa and 56.9MPa, the elongation after fracture is maintained at a considerable level, and the electric conductivity is improved from 38.8% IACS to 38.9% IACS.
TABLE 2 Properties of 7050 aluminum alloys subjected to different aging treatments
According to the invention, the 7-series aluminum alloy is subjected to stretching pre-strain + room temperature natural standing treatment after solid solution or on-line quenching, and then the strength, the electric conductivity and the corrosion resistance of the material can be simultaneously improved through two continuous heating processes with different heating rates, the strength exceeds the traditional T6 peak aging, the electric conductivity and the corrosion resistance reach or exceed the traditional T73, the combination of high strength and high corrosion resistance is realized, and the performance of the aluminum alloy material is remarkably improved. Meanwhile, the method is simple and convenient to operate, short in process flow and capable of obtaining obvious economic benefits.
Claims (10)
1. An aging heat treatment method of a 7 series aluminum alloy material is characterized by comprising the following steps:
carrying out solid solution or online quenching treatment on the 7 series aluminum alloy material to be processed;
then, stretching the 7 series aluminum alloy material at the elongation of 1-3%;
sawing the stretched 7-series aluminum alloy material according to a set length, and naturally standing at room temperature for 0-168h, wherein the length is more than 0;
then putting the 7 series aluminum alloy material into an aging furnace, and heating at a heating rate V in the aging furnace 1 Heating to 130-150 deg.C from the current starting temperature, and heating at a heating rate V 2 And (3) continuing heating to 170-220 ℃, stopping heating, taking out the 7 series aluminum alloy material from the aging furnace, and cooling to room temperature to finish the treatment of the 7 series aluminum alloy material.
2. The aging heat treatment method for a 7-series aluminum alloy material according to claim 1, wherein the drawing treatment is performed at normal temperature and the elongation is 2% to 3%.
3. The aging heat treatment method for a 7-series aluminum alloy material according to claim 1, wherein the room-temperature natural standing time is 0 to 72 hours and more than 0.
4. The aging heat treatment method for a 7-series aluminum alloy material according to claim 1, wherein the heating rate V is 1 ＜V 2 。
5. The aging heat treatment method for a 7-series aluminum alloy material according to claim 1 or 4, wherein the heating rate V is 1 The value range is less than or equal to V at 5 DEG C 1 ≤20℃/h。
6. The aging heat treatment method for a 7-series aluminum alloy material according to claim 5, wherein the heating rate V is 1 The value range is less than or equal to V at 5 DEG C 1 ≤10℃/h。
7. The aging heat treatment method for a 7-series aluminum alloy material according to claim 1 or 4, wherein the heating rate V is 2 The value range is not less than 20 ℃ and not more than V 2 ≤40℃/h。
8. The aging heat treatment method for a 7-series aluminum alloy material according to claim 1, wherein the 7-series aluminum alloy is heated at a heating rate V in an aging furnace 1 The starting temperature for starting heating is room temperature, or a certain temperature higher than room temperature and the certain temperature is less than 100 ℃.
9. The aging heat treatment method of the 7-series aluminum alloy material according to claim 1, wherein the 7-series aluminum alloy material is cooled naturally, by fan air cooling or by water mist cooling after tapping.
10. The aging heat treatment method for a 7-series aluminum alloy material according to claim 1, wherein the temperature of the solid solution or in-line quenching is 450 to 550 ℃.
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| CN102400068A (en) * | 2011-11-22 | 2012-04-04 | 中国航空工业集团公司北京航空材料研究院 | Non-isothermal aging (NIA) process of 7XXX aluminum alloy |
| CN108823472A (en) * | 2018-07-25 | 2018-11-16 | 江苏大学 | A kind of High Strength and Tenacity Al-Zn-Mg-Cu Aluminum Alloy and its heat treatment method |
| CN109136689A (en) * | 2018-10-22 | 2019-01-04 | 广西平果百矿高新铝业有限公司 | A kind of Al-Zn-Mg-Cu ultra-high-strength aluminum alloy and its crushing failure at high speed press quenching production method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102400068A (en) * | 2011-11-22 | 2012-04-04 | 中国航空工业集团公司北京航空材料研究院 | Non-isothermal aging (NIA) process of 7XXX aluminum alloy |
| CN108823472A (en) * | 2018-07-25 | 2018-11-16 | 江苏大学 | A kind of High Strength and Tenacity Al-Zn-Mg-Cu Aluminum Alloy and its heat treatment method |
| CN109136689A (en) * | 2018-10-22 | 2019-01-04 | 广西平果百矿高新铝业有限公司 | A kind of Al-Zn-Mg-Cu ultra-high-strength aluminum alloy and its crushing failure at high speed press quenching production method |
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