CN115198213A - Composite thermomechanical treatment method for regulating and controlling conductivity and mechanical property of aluminum alloy - Google Patents
Composite thermomechanical treatment method for regulating and controlling conductivity and mechanical property of aluminum alloy 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
- C22F1/05—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 of the Al-Si-Mg type, i.e. containing silicon and magnesium in approximately equal proportions
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0236—Cold rolling
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- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
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- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
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Abstract
The invention belongs to the technical field of aluminum alloy heat treatment, and discloses a composite deformation heat treatment method for regulating and controlling the conductivity and mechanical property of an aluminum alloy. The method comprises the following steps: 1) Carrying out cold rolling deformation on the deformed aluminum alloy plate to obtain a cold-rolled plate; 2) Preserving heat of the cold-rolled sheet, and then rapidly cooling to obtain a supersaturated solid solution; 3) Preserving the heat of the supersaturated solid solution state plate so as to finish intermediate pre-aging; 4) Directly carrying out variable temperature rolling on the alloy plate subjected to intermediate pre-aging; 5) And preserving the heat of the alloy subjected to variable temperature rolling so as to finish final aging. The method effectively utilizes the alloy deformation to increase the internal defects of the alloy, refine the clusters and the interaction effect in the heat treatment process, fully exerts the dispersion strengthening effect, realizes the synchronous promotion of the conductivity and the mechanical property of the alloy, especially has the most obvious promotion of the yield strength of the alloy and shows excellent plasticity. The invention also has the advantages of obvious energy saving and consumption reduction, and is easy to realize batch production.
Description
Technical Field
The invention relates to the technical field of aluminum alloy heat treatment, in particular to a composite thermomechanical treatment method for regulating and controlling the conductivity and mechanical property of aluminum alloy.
Background
Aluminum alloy has many advantages of low density, high specific strength, low resistivity, high thermal conductivity, easy molding, etc., is the second largest metallic structure material next to steel materials, and can be used as a conductor material instead of copper. Taking a new energy automobile as an example, the aluminum alloy can be used for replacing a steel plate to manufacture an automobile body and can also be used as a battery conductive bus bar, so that the weight of the automobile body is greatly reduced, and the weight is reduced to reduce energy consumption. Commercial 6000 series conductive aluminum alloys typified by 6101 and 6201 aluminum alloys have been popularized and applied in the fields of power transmission and the like. The 6000 series aluminum alloy takes Mg and Si as main alloy elements and can age and precipitate Mg 2 The Si strengthening phase is a heat-treatable strengthened aluminum alloy and is generally used in a peak-aged state. 6101 alloy has a tensile strength of up to 220MPa, a yield strength of about 180MPa, an electrical conductivity of about 55% IACS in the peak aged condition. Whereas for the 6201 alloy, its alloying element content is higher than 6101 alloy, which is correspondingly higher in mechanical properties, the yield strength may exceed 250MPa, but its electrical conductivity is less than 50% IACS. If the electrical conductivity needs to be further improved, the aging temperature needs to be increased or the aging time needs to be further prolonged, so that remarkable overaging is generated, the electrical conductivity is increased, but the mechanical property is remarkably reduced, and the difficulty of subsequent processing is increased.
At present, 6101 and 6201 alloy researches mainly focus on utilizing alloying, processing deformation, heat treatment and other means to regulate and control the morphology and distribution of the second phase of the alloy, reduce matrix lattice distortion and improve the mechanics and conductivity of the alloy. For the metal material, because of the influence of metal strength and conductive micro mechanism, the strength and conductivity are mutually restricted, and an obvious 'back-to-back' relationship is shown, namely the mechanical property is reduced after the conductive property is improved. How to solve the problem that the strengthening and the conductivity of 6000 series aluminum alloy are mutually restricted and balance the strength and the conductivity of the alloy is a key technical problem which needs to be solved urgently at present. For the influence of alloy elements, solid solution is reduced as much as possible, the alloy elements are promoted to be precipitated as a second phase, the adverse influence of lattice distortion caused by the solid solution on the electric conduction is inhibited, and the dispersion strengthening effect of the second phase is exerted, so that the electric conduction improvement and strengthening effects are obtained. The deformation and heat treatment process is combined, and the thermomechanical treatment process is developed, so that the comprehensive regulation and cooperative improvement of the strength, the plasticity and the electric conductivity can be realized.
The Chinese patent application publication No. CN 104694858A, thermal processing method for simultaneously improving the conductivity and strength of aluminum alloy, discloses a thermal processing method combining thermal deformation and solid solution aging. The invention aims at the 6000 series aluminum alloy of Al-Mg-Si-Cu base, and the specific components are as follows: 0.75% Mg, 0.75% Si, 0.8% Cu, 0.15% Mn, 0.15% Cr, 0.2% Fe, 0.01% Ti, the balance Al. Firstly, homogenizing a casting prepared billet, then carrying out hot rolling to obtain a plate with a certain thickness, carrying out solid solution and aging treatment on the plate, then naturally cooling, carrying out rolling deformation at room temperature, and further carrying out secondary aging treatment on the rolled and deformed plate. The synchronous improvement of the strength and the mechanical property can be realized, wherein the time of the secondary aging treatment reaches up to 35h, the obvious overaging is generated, the electric conductivity of the secondary aging treatment can reach up to 56.87 percent IACS, the tensile strength can still be maintained at 316MPa, and the elongation after fracture is 11.2 percent. Compared with the traditional solution aging treatment process after cold deformation, the strength can be improved by 100MPa, and the corresponding conductivity is improved by 5% IACS.
The technology relates to a thermomechanical treatment process of wrought aluminum alloy, and the alloy phase structure can be regulated and controlled based on the thermomechanical treatment, so that the excellent toughness of the wrought aluminum alloy is ensured. However, for the aluminum alloy for electric conduction, in addition to having as high electric conductivity as possible, sufficient strength property and excellent plastic deformability are required to meet the demand of the subsequent forming process. The power performance of the current new energy automobile is continuously improved, higher requirements on the conductivity of the conductive bus bar between the battery pack and the power system are provided, and meanwhile, excellent forming processing and complex bending of the wire arranging process are required to be guaranteed. It is one of the important researches on how to satisfy the excellent comprehensive performance of the aluminum alloy for the conductive bus bar by ensuring sufficient strength and excellent plasticity on the premise of obtaining the highest possible conductivity based on the 6000 series alloy.
The alloy aimed at by the above-mentioned published patent application has high content of Cu in order to obtain higher mechanical property, and belongs to a high Cu content wrought aluminum alloy system, although the alloy can obtain higher mechanical property, the plasticity is poor, the conductivity is relatively low, and the alloy is not suitable for conductive bus bar molding and high requirement on conductivity. At present, in order to obtain higher conductivity, the aluminum alloy is often subjected to long-time aging at higher temperature aiming at the wrought aluminum alloy, and although the higher conductivity can be obtained, the mechanical property of the wrought aluminum alloy is remarkably reduced, the aging temperature is high, the heat preservation time is long, and the energy consumption is high, and the production efficiency is low.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a composite heat treatment method which can obviously improve the conductivity of the aluminum alloy, has enough strength and good plastic deformation capability, is beneficial to improving the production efficiency and obviously reduces the energy consumption. The invention optimizes and determines the thermomechanical treatment process flow and obtains a better process parameter range. The process does not need to add any equipment, and only adds a combined flow of deformation and heat treatment.
The invention is realized by the following technical scheme:
a composite thermomechanical treatment method for regulating and controlling the conductivity and mechanical property of aluminum alloy comprises the following steps:
1) Carrying out cold rolling deformation on the deformed aluminum alloy plate to obtain a cold-rolled plate;
2) Placing the cold-rolled sheet in a heat preservation device for heat preservation, and then rapidly cooling to obtain a supersaturated solid solution, namely a supersaturated solid solution sheet;
3) Placing the supersaturated solid solution state plate in a heat preservation device for heat preservation so as to complete intermediate pre-aging;
4) Directly carrying out variable temperature rolling on the alloy plate subjected to the intermediate pre-aging;
5) And placing the alloy subjected to variable temperature rolling into a heat preservation device for heat preservation, thereby finishing final aging.
The wrought aluminum alloy plate in the step 1) is obtained by hot rolling, and is specifically obtained by casting a billet, performing homogenization heat treatment and performing high-temperature hot rolling on the wrought aluminum alloy. The temperature of the high-temperature hot rolling is 450-500 ℃; the temperature of the homogenization heat treatment is 550-580 ℃, and the time is 7-9 h.
The cold rolling deformation refers to cold rolling deformation of the plate at room temperature.
The rolling reduction of the cold rolling deformation is 10-20%.
The temperature of the heat preservation in the step 2) is 510-530 ℃, and the heat preservation time is 15-30 min.
The rapid cooling is cooling by using room temperature water. Specifically, the heat-insulated plate is placed in water for cooling or is subjected to water spraying atomization cooling.
The temperature for heat preservation in the step 3) is 200-240 ℃, and the time for heat preservation is 0.5-2 h.
The variable temperature rolling in the step 4) means that the total rolling reduction is 50-70%.
The variable-temperature rolling in the step 4) means that the alloy plate after the intermediate pre-aging is directly rolled without cooling, the temperature is gradually reduced in the rolling process, and the alloy plate after the intermediate pre-aging is rolled for multiple times in the natural cooling process. The rolling is multi-pass rolling, and the reduction of each pass of rolling is 5-15%; the rolling times are 4-15. When the controlled reduction of each pass is 10%, the rolling times are 5-7 times.
The final aging temperature in the step 5) is 210-240 ℃.
The heat preservation time in the step 5) is 1-35 h.
The cold rolling in the step 1) is to naturally cool the alloy plate after hot rolling to room temperature and then carry out cold rolling.
The aluminum alloy is 6000 series alloy.
The alloy prepared by the invention is an aluminum alloy for a conductive bus bar.
According to the invention, deformation and heat treatment are combined, the deformation process is utilized to increase the internal defects of the alloy, and precipitated phase clusters are refined. On the one hand, the defects promote diffusion during heat treatment and provide activation energy for phase precipitation, and the clusters promote nucleation sites during heat treatment. The combination of the several aspects is beneficial to improving the heat treatment efficiency and reducing the heat treatment temperature. The precipitation of a large amount of dispersion particles can also reduce the solid solubility of alloy elements in a matrix, reduce lattice distortion and fully exert the dispersion strengthening effect. Finally, the electric conduction and mechanical property of the alloy are synchronously improved. The alloy can meet the comprehensive mechanical and conductive performance required by the current 'replacing copper by aluminum' in power battery conductive busbars and other power transmission systems.
Compared with the existing preparation process of wrought aluminum alloy, particularly wrought conductive aluminum, the preparation process has the following outstanding advantages:
(1) The invention obtains a preparation technology of wrought aluminum alloy which has outstanding comprehensive properties of high conductivity, high strength, excellent plasticity and the like.
(2) The invention realizes the synchronous improvement of the conductivity and the mechanical property of the alloy. Particularly, on the premise that the conductivity is remarkably improved compared with that of the traditional process, the yield strength of the alloy is greatly improved by more than 3 times.
(3) For 6101 electrically conductive aluminum alloys that are widely used, the electrical conductivity of the alloy treated according to the present invention is significantly increased over 61% IACS up to 61.4% IACS, which is close to that of electrical aluminum alloys (about 62% IACS).
(4) Aiming at 6101 conductive aluminum alloy with wide application, the alloy treated by the invention has the yield strength of more than 150MPa, good plasticity, and the fracture elongation of more than 20 percent, and is beneficial to subsequent processing.
(5) Compared with the traditional process which greatly increases the aging temperature and prolongs the heat preservation time as much as possible to realize high conductivity, the method has the advantages that the final aging temperature is reduced by 40-60 ℃ under the condition that the conductivity of the alloy is obviously higher than that of the alloy obtained by the traditional process technology, and the method has obvious energy saving and consumption reduction advantages.
(6) The process provided by the invention can be used for producing the wrought aluminum alloy with excellent conductivity only by adjusting the production steps of the existing production line without adding new equipment, and is easy to realize batch production.
Drawings
FIG. 1 is a simplified diagram of a conventional heat treatment process for wrought aluminum alloys;
FIG. 2 is a graph showing the effect of aging time on the conductivity of alloys treated at different aging temperatures in comparative example 1;
FIG. 3 is a graph of the effect of aging time on the yield strength of alloys treated at different aging temperatures for comparative example 1;
FIG. 4 is a simplified diagram of a composite thermomechanical treatment process of the present invention;
FIG. 5 is a graph showing the effect of aging time on the electrical conductivity of the alloy in example 1;
FIG. 6 is a graph showing the effect of aging time on alloy yield strength in example 1.
Detailed Description
The present invention will be described in further detail with reference to specific examples, but the embodiments of the present invention are not limited thereto.
To better illustrate the effect of the present invention, a solution aging process for producing 6101 wrought conductive aluminum alloy in actual production was used as comparative example 1.
Comparative example 1
6101 the aluminum alloy is a common wrought aluminum alloy for preparing bus conductors, and the preparation process flow thereof comprises smelting, manufacturing billet by a water-cooled crystallizer, homogenizing annealing, and hot rolling at high temperature to obtain the sheet material under the condition of batch production. The composition of alloy 6101 in comparative example 1 is: 0.38% Mg, 0.35% Si, 0.11% Fe, 0.04% Cu, 0.03% Zn, 0.01% Ti, the balance being Al.
The wrought aluminum alloy used in the invention is firstly prepared into a plate through casting billet preparation, homogenization heat treatment and high-temperature hot rolling. Wherein the homogenization process comprises the steps of keeping the temperature at 560 ℃ for 8 hours, and cooling along with the furnace to dissolve the alloy phase as much as possible and ensure full and uniform components. Heating the homogenized and annealed billet to 460 ℃, and hot-rolling the billet to 20mm to obtain the plate with the rolling deformation of more than 95%. And cooling the hot rolled plate to room temperature for standby, and then carrying out solid solution aging treatment to obtain the required performance. The comparative example is the traditional solid solution aging process, and is the most widely applied production process for manufacturing 6101 alloy conductive aluminum alloy in the current practical production.
Solid solution aging treatment: firstly, carrying out solid solution treatment on a plate cooled to room temperature, soaking the plate into room temperature water after keeping the temperature at 530 ℃ for 1h to obtain supersaturated solid solution, and then carrying out artificial aging treatment at different temperatures respectively. In the comparative example, three temperatures are selected for aging treatment, namely 190 ℃, 230 ℃ and 280 ℃, and the longest holding time is 35h. It should be noted that in actual production, if the alloy strength requirement is higher, temperature aging of about 190 ℃ is generally adopted, and when the electrical conductivity is improved as much as possible on the premise of meeting the basic mechanical requirements, higher temperature aging is often adopted.
The comparative example was treated with a conventional heat treatment process for hot rolled plate, the process flow of which is shown in fig. 1.
The conductivity of the alloy after the various processes was measured with an eddy current conductivity meter (model: foster FIRST FD101, standard: GB/T12966). And measuring the mechanical properties of the alloy under different conditions by using an electronic universal material testing machine (model: AG-X-100KN, standard: GB/T228-2010), and obtaining corresponding tensile strength, yield strength and elongation at break.
FIG. 2 shows the effect of aging time on the conductivity of the alloy at different aging temperatures in comparative example 1. From the trend, the change trend of the conductivity along with the time is relatively close, and the conductivity rises rapidly and linearly in the initial stage, then slowly rises, and enters a platform area after reaching a maximum value. As can be seen from the comparison in the inflection point region, when the effective temperature is 190 ℃, the initial conductivity increase rate of the aging is low, only about 0.6% IACS/h, while when the temperatures are 230 ℃ and 280 ℃, the increase rate is significantly higher than 190 ℃, about 3%. As compared with the maximum value, it can reach 58.5% IACS at 190 deg.C, while it can reach 59.5% IACS and 59.9% IACS respectively when the temperature is 230 deg.C and 280 deg.C, and the time to reach the maximum value is shorter, from about 30h to 24h.
And further testing the mechanical properties of the alloy in different states when the aging time is 0h, 1h, 10h, 25h and 35h respectively, and mainly comparing the change of the yield strength. FIG. 3 is a graph of the alloy yield strength versus aging time for different aging temperatures of comparative example 1. Obviously, the strength of the solid solution alloy is improved to different degrees after the appropriate time aging, wherein the strengthening effect is relatively more obvious when the temperature is lower. However, as the aging time is further increased, the strength is decreased to some extent, and the higher the aging temperature is, the larger the decrease is. The lower the ageing temperature, the lower the electrical conductivity and the greater the yield strength. 58.5% of the yield strength and 21% of elongation at break corresponding to the IACS at 190 ℃; 59.5% of the yield strength and elongation at break corresponding to IACS at 230 ℃ of 92 MPa; whereas at 280 ℃ ageing the maximum conductivity achieved was close to 60% IACS, but the corresponding yield strength was reduced to 55MPa, with an elongation at break of 26%.
To further illustrate the effects of the present invention, the following examples are given to illustrate the present invention.
Example 1
The alloy used in this example was alloy 6101. The components of the alloy, the preparation of the ingot, the homogenizing annealing and the hot rolling process parameters are the same as those of the comparative example 1, and the difference from the comparative example 1 is directed to the subsequent heat treatment process flow of the hot rolled plate. In this embodiment, a hot rolled plate is used as a raw material (the hot rolled plate is also called as a supplied plate, and is cooled to room temperature), and the composite shape heat treatment process provided by the present invention is used for treatment, and the process flow is shown in fig. 4.
The composite shape heating treatment in the embodiment means that a hot rolled plate is subjected to short-time rapid solid solution after being properly cold rolled, intermediate pre-aging is applied after continuous quenching, then variable temperature rolling is performed by utilizing pre-aging preheating, and a final product is obtained after long-time artificial aging.
The composite thermomechanical treatment method for regulating and controlling the conductivity and the mechanical property of the aluminum alloy in the embodiment specifically comprises the following steps:
(1) Cold rolling
A cold rolling deformation was applied to a hot-rolled sheet having a thickness of about 20mm (a sheet cooled to room temperature), and the reduction was 20%.
(2) Fast solid solution
And (3) rapidly dissolving the cold-rolled sheet in a solid solution at 530 ℃ for 15min, and then rapidly cooling the cold-rolled sheet in room-temperature water (cooling and keeping the temperature for about 1 min) to obtain a supersaturated solid solution.
(3) Intermediate pre-ageing
And (3) putting the solid solution alloy into a heat preservation furnace for pre-aging, wherein the temperature is 240 ℃, and preserving heat for 0.5h.
(4) Rolling at variable temperatures
Directly starting multi-pass rolling (5-pass rolling and natural cooling in the rolling process, wherein the reduction of each pass is generally reduced by 10-15 ℃, the initial reduction speed is relatively high, the subsequent reduction speed is relatively low), the reduction is controlled to be 10% in each pass, and the total pressure is 50% after the intermediate pre-aging alloy is discharged from the furnace. The temperature is gradually reduced in the rolling process, and the temperature-changing rolling process is completed.
(5) Final ageing
And (3) carrying out final aging treatment on the pre-aged variable-temperature rolled alloy, wherein the aging temperature is 230 ℃, and the time is prolonged to 35h at most.
To better understand the design basis of the process flow and the determination basis of the process parameter range of the invention, the basic principle for realizing the invention is explained as follows:
6101 alloy is a typical Al-Mg-Si based wrought aluminium alloy, the main mechanisms for achieving its strengthening include solid solution, deformation and Mg 2 Si aging strengthening and the like. Wherein the precipitation phase which generates fine dispersion distribution based on the aging process is the most main strengthening mode. The basic premise of aging strengthening is to obtain a supersaturated solid solution, and the method applies cold deformation to the alloy before solid solution, so that on one hand, lattice distortion is generated in the content of the alloy, and deformation dislocation and the like are introduced and are solidThe solution treatment process solute diffusion provides the driving force and fast diffusion path, thereby effectively accelerating the rate of solid solution. Meanwhile, partial intragranular defects can also be remained by rapid solid solution, and the existence of the defects can influence the subsequent aging process.
In the short-time pre-aging process, mg and Si atoms are enriched firstly to form GP zones, so that beta 'and beta' phases with high density distribution are formed, and the optimal aging strengthening effect, namely the peak aging state, is gradually achieved. For 6101 alloys, the peak age will generally occur after 2-3h, followed by stable Mg 2 Si phase is separated out and enters an overaging stage, and the strength is gradually reduced. The invention needs to ensure that the alloy begins to deform before peak aging, and gradually reduces the temperature, namely variable temperature rolling. The internal organization changes during this process mainly include the following aspects: 1) The rolling process is implemented at a higher temperature, and the aging precipitation process is still continued; 2) The defects such as internal dislocation, lattice distortion and the like can be promoted to be generated under the action of external force; 3) Deformation at higher temperatures is accompanied by the development of dynamic recrystallization; 4) Internal defects, external deformation, recrystallization and aging precipitation interaction.
On one hand, the formed high-density beta 'phase and beta' phase can be crushed under the action of external force and are distributed in a finer and dispersed manner, and internal defects such as dislocation and the like can be introduced. The alloy after variable temperature rolling contains higher density beta 'phase and beta' phase, and simultaneously has a plurality of defects. After further aging treatment, on the one hand, the beta 'phase and the beta' phase are further converted into Mg 2 Si phase, and Mg during further aging of a large number of dislocations in the interior 2 The precipitation of Si phase provides nucleation site and reduces Mg 2 Activation energy of Si phase nucleation, acceleration of aging response of 6101 aluminum alloy and promotion of Mg 2 The Si phase is precipitated more finely and dispersedly. Not only can improve the performance of the alloy, but also can shorten the time required by the alloy to reach the peak aging, shorten the production period and reduce the production cost of enterprises.
FIG. 5 is a graph showing the effect of aging time on the electrical conductivity of the alloy in example 1. The trend is similar to that of comparative example 1 at 280 ℃. In comparison, the initial rise rate was much faster, reaching 13.3% IACS/h, the maximum conductivity reached 61.1% IACS, and the aging time to reach the maximum conductivity was about 25 h. The electrical conductivity of common electrical aluminum is about 62% iacs. The alloy 6101 treated in this example has an electrical conductivity approaching that of electrical aluminum, only 0.9% IACS lower.
Similarly, the mechanical properties of the alloys were tested at aging times of 0h, 1h, 10h, 25h and 35h. FIG. 6 is a graph showing the effect of aging time on alloy yield strength in example 1. But has a significant difference from the rule of the influence of the aging time on the yield strength of the alloy in the comparative example 1. The alloy of the embodiment undergoes short-time pre-aging and undergoes the variable temperature rolling process, and the dual factors of the solid solution aging and the deformation strengthening act, so that the alloy already shows high yield strength before the aging starts, reaching 231.5MPa, and the electrical conductivity of the alloy is obviously 53.5 percent IACS. As the aging time is prolonged, the yield strength of the alloy is gradually reduced, but the conductivity is rapidly improved. The maximum electrical conductivity of the alloy in this example reached 61.1% IACS, corresponding to a yield strength of still up to 180MPa and an elongation at break of 22%.
This example compared to comparative example 1, it was possible to obtain a higher electrical conductivity, about 1.6% IACS higher, or even more than 280 ℃ higher, about 1.2% IACS, at a similar aging temperature (230 ℃). More significantly, higher initial conductivity ramp-up rates are exhibited, while at the same time the alloy still exhibits very excellent yield strength at the point of maximum conductivity. The yield strength of the alloy is improved by about 1 time compared with that of the alloy in comparative example 1 at 230 ℃ and is 3.3 times of that of the alloy at 280 ℃. In addition, the comparative energy consumption shows that the solid solution time can be shortened by one time, and the aging temperature can be reduced by about 50 ℃ under the condition of obtaining similar conductivity.
Example 2
The alloy used in this example was also alloy 6101. The alloy components, the preparation of the ingot, the homogenizing annealing and the hot rolling process parameters are completely the same as those of the comparative example 1, and the difference from the comparative example 1 is the subsequent heat treatment process flow of the hot rolled plate. In the embodiment, a hot rolled plate is used as a raw material, and the composite heat treatment process provided by the invention is used for treatment, and the process flow is completely the same as that in the embodiment 1. Except that there are differences in process parameters.
The composite thermomechanical treatment method for regulating and controlling the conductivity and the mechanical property of the aluminum alloy in the embodiment specifically comprises the following steps:
(1) Cold rolling
The hot rolled sheet with a thickness of about 20mm was subjected to cold rolling deformation at a reduction of 20%.
(2) Fast solid solution
And (3) rapidly dissolving the cold-rolled sheet in solid solution at 510 ℃ for 30min, and then rapidly cooling the cold-rolled sheet in room-temperature water to obtain a supersaturated solid solution.
(3) Intermediate pre-ageing
And (3) putting the solid solution alloy into a heat preservation furnace for pre-aging, wherein the temperature is 230 ℃, and preserving heat for 1h.
(4) Rolling at variable temperatures
Directly starting multi-pass rolling (7 passes) after discharging the intermediate pre-aging alloy, wherein the controlled reduction of each pass is 10%, and the total reduction is 70%. The temperature is gradually reduced in the rolling process, and the temperature-changing rolling process is completed.
(5) Final ageing
And carrying out final aging treatment on the pre-aged variable temperature rolled alloy, wherein the aging temperature is 210 ℃, and the time is prolonged to 35h at most.
Likewise, the electrical conductivity and mechanical properties of the alloys were tested. The aging time has a similar effect on the conductivity of the alloy as that obtained in example 1, except that the specific performance data is different. The rate of increase in electrical conductivity of the alloy at the initial stage was 9.73% IACS/h, the maximum electrical conductivity reached 61.1% IACS, and the aging time to reach the maximum electrical conductivity was about 25 h. The alloy 6101 treated in this example has an electrical conductivity approaching that of electrical aluminum, only 0.9% IACS lower.
The yield strength change law is similar to that of example 1, but the initial yield strength value is higher than that of example 1 and reaches 261MPa. This should be related to the higher rolling amount in the initial cold rolling deformation and the temperature-varying rolling deformation in the present embodiment. As the aging time is prolonged, the yield strength of the alloy is gradually reduced, but the conductivity is rapidly improved. The maximum electrical conductivity of the alloy in this example reached 61.1% IACS, corresponding to a yield strength of up to 194MPa and an elongation at break of 21%.
This example compared to comparative example 1, it was possible to obtain a higher conductivity, about 1.6% increase in IACS, than the comparable example 1, also higher than the conductivity at the aging temperature of 280 ℃ by about 1.2% IACS. More significantly, higher initial conductivity increase rates are exhibited, while at the same time the alloys still exhibit very excellent yield strengths at the highest conductivities. The yield at 230 ℃ is about 1 time as compared to 3.5 times as high as the yield strength at 280 ℃ in comparative example 1. Furthermore, it can be seen from the comparison of energy consumption that the solution time can be doubled and the final aging temperature can be reduced by about 70 ℃ at higher conductivities.
Example 3
The alloy used in this example was alloy 6101. The alloy components, the preparation of the ingot, the homogenizing annealing and the hot rolling process parameters are completely the same as those of the comparative example 1, and the difference from the comparative example 1 is the subsequent heat treatment process flow of the hot rolled plate. In the embodiment, a hot rolled plate is used as a raw material, and the composite heat treatment process provided by the invention is used for treatment, and the process flow is completely the same as that in the embodiment 1. Except that there are differences in process parameters.
The composite thermomechanical treatment method for regulating and controlling the conductivity and the mechanical property of the aluminum alloy in the embodiment specifically comprises the following steps:
(1) Cold rolling
The hot rolled sheet with a thickness of about 20mm was subjected to cold rolling deformation with a reduction of 15%.
(2) Fast solid solution
And (3) rapidly dissolving the cold-rolled sheet in solid solution at 520 ℃ for 20min, and then rapidly cooling the cold-rolled sheet in room-temperature water to obtain a supersaturated solid solution.
(3) Intermediate pre-ageing
And (3) putting the solid solution alloy into a heat preservation furnace for pre-aging, wherein the temperature is 200 ℃, and preserving heat for 2h.
(4) Rolling at variable temperatures
Directly starting multi-pass rolling after discharging the intermediate pre-aging alloy, wherein the controlled reduction of each pass is 10%, and the total reduction is 60%. The temperature is gradually reduced in the rolling process, and the temperature-changing rolling process is completed.
(5) Final ageing
And carrying out final aging treatment on the pre-aged variable temperature rolled alloy, wherein the aging temperature is 240 ℃, and the time is prolonged to 35h at most.
Likewise, the electrical conductivity and mechanical properties of the alloys were tested. The law of the effect of the ageing time on the electrical conductivity of the alloy is similar to that obtained in example 1, except that the specific performance data are different. The initial rise rate was 12.34% IACS/h, the maximum conductivity reached 61.4% IACS, and the aging time for reaching the maximum conductivity was about 25 h. The alloy 6101 treated in this example has an electrical conductivity approaching that of electrical aluminum, only 0.6% IACS lower.
The yield strength change law was similar to that of example 1, but the initial yield strength value was relatively lower than that of example 1, 216MPa. This should be associated with the relatively low pre-ageing temperature in this embodiment. As the aging time is prolonged, the yield strength of the alloy is gradually reduced, but the conductivity is rapidly improved. The maximum electrical conductivity of the alloy in this example reached 61.4% IACS, corresponding to a yield strength of 146MPa and an elongation at break of 21%.
This example can achieve higher electrical conductivity at similar aging temperatures (230 ℃ C.), an increase of about 1.9% IACS, and also higher than the electrical conductivity at 280 ℃ aging temperature, about 1.5% IACS, as compared to comparative example 1. More significantly, higher initial conductivity ramp-up rates are exhibited, while at the same time the alloy still exhibits excellent yield strength at the point of maximum conductivity. The yield is improved by about 50% times compared with the yield at 230 ℃ aging in comparative example 1, and is 2.7 times of the yield strength at 280 ℃. In addition, the energy consumption is compared, the solid solution time is only 1/3 of that of the traditional process, and the final aging temperature can be reduced by about 40 ℃.
Example 4
The alloy used in this example was alloy 6101. The alloy components, preparation of ingot, homogenizing annealing and hot rolling technological parameters are completely the same as in comparative example 1, and the difference from comparative example 1 is directed to the subsequent heat treatment technological process of the hot rolled plate. In the embodiment, a hot rolled plate is used as a raw material, the composite shape heating treatment process provided by the invention is used for treatment, and the process flow is completely the same as that in the embodiment 1. Except that there are differences in process parameters.
The composite thermomechanical treatment method for regulating and controlling the conductivity and the mechanical property of the aluminum alloy in the embodiment specifically comprises the following steps:
(1) Cold rolling of steel
The hot rolled sheet with a thickness of about 20mm was subjected to cold rolling deformation with a reduction of 10%.
(2) Fast solid solution
And (3) rapidly dissolving the cold-rolled sheet in solid solution at 530 ℃ for 15min, and then rapidly cooling the cold-rolled sheet in room-temperature water to obtain a supersaturated solid solution.
(3) Intermediate pre-ageing
And (3) putting the solid solution alloy into a heat preservation furnace for pre-aging, wherein the temperature is 230 ℃, and preserving heat for 1h.
(4) Rolling at variable temperatures
Directly starting multi-pass rolling after discharging the intermediate pre-aging alloy, wherein the rolling reduction of each pass is controlled to be 10%, and the total rolling reduction is controlled to be 70%. The temperature is gradually reduced in the rolling process, and the temperature-changing rolling process is completed.
(5) Final ageing
And (3) carrying out final aging treatment on the pre-aged variable-temperature rolled alloy, wherein the aging temperature is 220 ℃, and the time is prolonged to 35h at most.
Likewise, the electrical conductivity and mechanical properties of the alloys were tested. The law of the effect of the ageing time on the electrical conductivity of the alloy is similar to that obtained in example 1, except that the specific performance data are different. The initial rise rate was 10.21% IACS/h, the maximum conductivity reached 61.4% IACS, and the aging time for reaching the maximum conductivity was about 25 h. The alloy 6101 treated in this example has an electrical conductivity approaching that of electrical aluminum, only 0.6% IACS lower.
The yield strength change law is similar to that of the alloy in the embodiment 1, but compared with the alloy in the embodiment 1, the initial yield strength value is higher and reaches 263MPa, and the initial yield strength value is close to that of the alloy in the embodiment 2. This should be related to the higher rolling amount in the initial cold rolling deformation and the temperature-varying rolling deformation in the present embodiment. As the aging time is prolonged, the yield strength of the alloy is gradually reduced, but the conductivity is rapidly improved. The maximum electrical conductivity of the alloy in this example reached 61.4% IACS, corresponding to a yield strength of 184MPa and an elongation at break of 23%.
This example, compared to comparative example 1, can achieve a higher conductivity at a similar aging temperature (230℃.), an increase of about 1.9% IACS, about 1.4% IACS greater than the conductivity at the aging temperature of 280℃. More significantly, higher initial conductivity increase rates are exhibited, while at the same time the alloys still exhibit excellent yield strengths at the highest conductivities. The yield is improved by about one time compared with the yield at 230 ℃ of comparative example 1, and is 3.3 times of the yield strength at 280 ℃. In addition, the energy consumption is compared, the solid solution time is only 1/4 of that of the traditional process, and the final aging temperature can be reduced by about 60 ℃.
Example 5
The alloy used in this example was alloy 6101. The alloy components, preparation of ingot, homogenizing annealing and hot rolling technological parameters are completely the same as in comparative example 1, and the difference from comparative example 1 is directed to the subsequent heat treatment technological process of the hot rolled plate. In the embodiment, a hot rolled plate is used as a raw material, the composite shape heating treatment process provided by the invention is used for treatment, and the process flow is completely the same as that in the embodiment 1. Except that there are differences in the process parameters.
The composite thermomechanical treatment method for regulating and controlling the conductivity and the mechanical property of the aluminum alloy in the embodiment specifically comprises the following steps:
(1) Cold rolling
The hot rolled sheet with a thickness of about 20mm was subjected to cold rolling deformation with a reduction of 10%.
(2) Fast solid solution
And (3) rapidly dissolving the cold-rolled sheet in a solid solution at 520 ℃ for 20min, and then rapidly cooling the cold-rolled sheet in room-temperature water to obtain a supersaturated solid solution.
(3) Intermediate pre-ageing
And (3) putting the solid solution alloy into a heat preservation furnace for pre-aging, wherein the temperature is 220 ℃, and preserving heat for 2 hours.
(4) Rolling at variable temperatures
Directly starting multi-pass rolling after discharging the intermediate pre-aging alloy, wherein the controlled reduction of each pass is 10%, and the total reduction is 60%. The temperature is gradually reduced in the rolling process, and the temperature-changing rolling process is completed.
(5) Final aging of
And carrying out final aging treatment on the pre-aged variable temperature rolled alloy, wherein the aging temperature is 230 ℃, and the time is prolonged to 35h at most.
Similarly, the conductivity and mechanical properties of the alloys were tested. The aging time has a similar effect on the conductivity of the alloy as that obtained in example 1, except that the specific performance data is different. The initial rate of rise was 6.88% IACS/h, the maximum electrical conductivity thereof reached 61.2% IACS, and the aging time to reach the maximum electrical conductivity was also about 25 h. The 6101 alloy treated with this example had a conductivity approaching that of electrical aluminum, only 0.8% IACS lower.
The yield strength change law is similar to that of example 1, the initial yield strength value is 236MPa, the yield strength of the alloy is gradually reduced along with the prolonging of the aging time, but the electric conductivity is rapidly improved. The maximum electrical conductivity of the alloy in this example reached 61.2% IACS, corresponding to a yield strength of still up to 168MPa, with an elongation at break of 20%.
This example can achieve a higher electrical conductivity at a similar aging temperature (230 ℃ C.), an increase of about 1.7% IACS than that of comparative example 1, and an increase of about 1.3% IACS than that at an aging temperature of 280 ℃ C. More significantly, higher initial conductivity ramp-up rates are exhibited, while at the same time the alloy still exhibits excellent yield strength at the point of maximum conductivity. The yield improvement is about 80% over the 230 ℃ age in comparative example 1, which is 3.1 times the yield strength at 280 ℃. In addition, the comparative energy consumption shows that the solid solution time is only 1/3 of that of the traditional process, and the final aging temperature can be reduced by about 50 ℃.
To better compare the performance of the present invention, the key performance parameters of the alloys prepared in comparative example 1 and examples 1-5 and their performance improvement data compared to the conventional process are summarized in table 1. It should be noted that the comparative lifting ratio and the comparative increase value in the table are both based on the data of the aging at 280 ℃ in comparative example 1.
Obviously, the electrical conductivity of the alloys prepared by the process of the present invention exceeded 61% of the IACS. Compared with the aging at 280 ℃ in the comparative example 1, the electrical conductivity is generally improved by 1.1-1.5% IACS, more remarkably, the yield strength is generally improved by about 3 times, the remarkable synchronous improvement of the electrical conductivity and the mechanical property is shown, and the improvement of the yield strength is particularly remarkable. In addition, the temperature of final aging is reduced by 40-60 ℃ while the higher conductivity is achieved, thereby being beneficial to energy conservation and consumption reduction.
To better illustrate the rate of conductivity increase and the aging time required to achieve the set conductivity index for the alloys of the present invention, the aging time data required to achieve the maximum conductivity for the alloys of the example preparations of comparative example 1 is summarized in Table 2. It is specifically noted that 58.5% IACS, 59.5% IACS and 59.9% IACS in the table correspond to the maximum values of the aged electrical conductivity at 190 deg.C, 230 deg.C and 280 deg.C in comparative example 1, respectively. It can be seen that comparative example 1 only required 58.5% IACS, and 35h, for the time at 190 ℃ and only 1.5h maximum for the present invention; whereas the time to reach the maximum conductivity at 230 ℃ in comparative example 1 was shortened from 30h to at most 4h. The time to reach the maximum conductivity of comparative example 1 at 280 ℃ is shortened from 25h to at most 8h.
TABLE 1 statistical table of key performance parameters and enhanced data for alloys prepared in comparative example 1 and examples 1-5
Description of the drawings: the comparative boost/increase values are all based on the performance achieved at an ageing temperature of 280 c in comparative example 1.
TABLE 2 comparison of aging times required for alloys prepared in examples 1-5 to reach the maximum conductivity for the alloy prepared in comparative example 1
Description of the drawings: 58.5% IACS, 59.5% IACS and 59.9% IACS correspond to the maximum values reached by the aged electrical conductivity at 190 ℃, 230 ℃ and 280 ℃ in comparative example 1, respectively.
Based on the description of the embodiment, the key point of the composite shape heat treatment process is that the conductive aluminum alloy is subjected to rapid solid solution after cold rolling, and pre-aging and variable temperature rolling are applied in the middle, so that the conductivity and the mechanical property of the conductive aluminum alloy are effectively and synchronously improved, and the conductive aluminum alloy not only shows excellent conductivity, but also has outstanding yield strength performance and better plastic deformation performance. The requirements of the new energy automobile battery conducting bus bar and other power transmission structural parts can be well met. Compared with the traditional process, under the condition of equivalent conductivity of electric conduction, the time is greatly reduced, the temperature is correspondingly and remarkably reduced, and the energy consumption is reduced due to the improvement of the efficiency and the reduction of the temperature, so that the advantages of energy conservation and consumption reduction are remarkable.
In order to more conveniently illustrate the implementation effect of the invention, the invention further changes the process flow or the process sequence, processes the 6101 alloy hot-rolled sheet, and performs comparison and description.
Comparative example 2
The alloy used in this comparative example was 6101 alloy. The alloy components, ingot preparation, homogenizing annealing and hot rolling process parameters are completely the same as those of comparative example 1, except that the subsequent heat treatment process flow of the hot rolled plate is adopted. The alloy is treated by a hot working method combining thermal deformation and solid solution aging, which is disclosed in Chinese patent CN 104694858A, a hot working method for simultaneously improving the conductivity and strength of aluminum alloy.
From the process flow, the process flow of the comparative example is mainly different from the process flow of the invention in that: cold rolling is not carried out on the plate before solid solution; after solid solution, the alloy is cooled down after intermediate pre-aging, then is placed for a period of time and then is subjected to cold rolling instead of direct variable temperature rolling. The detailed process flow and the parameters thereof are as follows:
(1) Solution treatment
Taking a hot rolled plate as a raw material, preserving heat for 30min at the temperature of 530 ℃, and then putting the hot rolled plate into room-temperature water for rapid cooling to obtain a supersaturated solid solution.
(2) Intermediate pre-ageing
Putting the solid solution alloy into a heat preservation furnace for pre-aging at 230 ℃, taking out after heat preservation for 1h, and cooling the alloy in a room temperature cold zone
(3) Cold rolling at room temperature
Impurities are finished on the sample after the pre-aging treatment and cooling at room temperature, the reduction is controlled to be 10% in each pass, and the total pressure is 70%.
(4) Final ageing
And (3) carrying out final aging treatment on the pre-aged variable-temperature rolled alloy, wherein the aging temperature is 220 ℃, and the time is prolonged to 35h at most.
The change in electrical conductivity of the test alloys also rose rapidly at the early stage of aging, reaching 7.51% IACS/h, but the maximum electrical conductivity was only 59.5% IACS, the time for aging to reach the maximum electrical conductivity was relatively long, requiring about 30 h. The corresponding yield strength is up to 104MPa, and the elongation at break is 22%. The yield strength is improved compared to comparative example 1, but is significantly lower than the mechanical properties achievable with the present invention.
Comparative example 3
The alloy used in this comparative example was 6101 alloy. The alloy components, ingot preparation, homogenizing annealing and hot rolling process parameters are completely the same as those of comparative example 1, except that the subsequent heat treatment process flow of the hot rolled plate is adopted. The main difference lies in that the order of solid solution and cold rolling is adjusted, and the technological process includes quick solid solution, cold rolling, intermediate aging, variable temperature rolling and final aging treatment. The detailed process flow and the parameters thereof are as follows:
(1) Fast solid solution
And (3) rapidly dissolving the cold-rolled sheet in solid solution at 520 ℃ for 1h, and then rapidly cooling the cold-rolled sheet in room-temperature water to obtain a supersaturated solid solution.
(2) Cold rolling
The hot rolled sheet with a thickness of about 20mm was subjected to cold rolling deformation with a reduction of 10%.
(3) Intermediate pre-ageing
And (3) putting the solid solution alloy into a heat preservation furnace for pre-aging at the temperature of 220 ℃ for 1h.
(4) Rolling at variable temperatures
Directly starting multi-pass rolling after discharging the intermediate pre-aging alloy, wherein the controlled reduction of each pass is 10%, and the total reduction is 50%. The temperature is gradually reduced in the rolling process, and the temperature-changing rolling process is completed.
(5) Final ageing
And carrying out final aging treatment on the pre-aged variable temperature rolled alloy, wherein the aging temperature is 230 ℃, and the time is prolonged to 35h at most.
The electrical conductivity of the test alloys also rose rapidly at the early stage of aging to 6.08% IACS/h, but the highest electrical conductivity reached 60.1% IACS, the aging time to reach the highest electrical conductivity required about 25h, corresponding to a yield strength of 134MPa and an elongation at break of 20%. Compared with comparative example 1, the yield strength is improved, but the conductivity and the mechanics are lower than those of the invention, and the comprehensive performance is lower. And the time required in the solid solution stage is longer.
Comparative example 4
The alloy used in this comparative example was 6101 alloy. The alloy components, preparation of ingot, homogenization annealing and hot rolling technological parameters are completely the same as those of comparative example 1, except that the subsequent heat treatment technological process of the hot rolled plate is adopted. The main difference is that the comparative example does not have one cold rolling, but directly carries out cold rolling after solid solution, and then directly carries out final aging treatment. The detailed process flow and the parameters thereof are as follows:
(1) Fast solid solution
Directly carrying out solid solution quenching on the hot-rolled plate at the temperature of 520 ℃ for 1h, and then putting the hot-rolled plate into room-temperature water for rapid cooling to obtain a supersaturated solid solution.
(2) Cold rolling of steel
The solid solution plate is rolled for multiple times at room temperature, the rolling reduction of each time is controlled to be 10%, and the total rolling reduction is 60%.
(3) Final ageing
And (3) carrying out final aging treatment on the cold-rolled alloy, wherein the aging temperature is 230 ℃, and the time is prolonged to 35h at most.
The electrical conductivity of the tested alloy changed at a relatively high rate of increase of initial electrical conductivity at aging, reaching 10.23% IACS/h, but the maximum electrical conductivity was only 59.7% IACS, and the aging time to reach the maximum electrical conductivity required about 25h, at which time the corresponding yield strength was also relatively low, only 109MPa, and the elongation at break was 20%. Compared with comparative example 1, the yield strength is improved, but the conductivity and the mechanics are lower than those of the invention, and the comprehensive performance is lower.
Comparative example 5
The alloy used in this comparative example was 6101 alloy. The alloy components, ingot preparation, homogenizing annealing and hot rolling process parameters are completely the same as those of comparative example 1, except that the subsequent heat treatment process flow of the hot rolled plate is adopted. The main difference between this comparative example and the heat treatment process of the present invention is that the sample was cooled to room temperature after intermediate aging, then subjected to secondary cold rolling, and then subjected to final aging. The detailed process flow and the parameters thereof are as follows:
(1) Cold rolling of steel
The hot rolled sheet with a thickness of about 20mm was subjected to cold rolling deformation with a reduction of 10%.
(2) Fast solid solution
And (3) rapidly dissolving the cold-rolled sheet in a solid solution at 520 ℃ for 20min, and then rapidly cooling the cold-rolled sheet in room-temperature water to obtain a supersaturated solid solution.
(3) Intermediate pre-ageing
And (3) putting the solid solution alloy into a heat preservation furnace for pre-aging, wherein the temperature is 220 ℃, and preserving heat for 2 hours.
(4) Secondary cold rolling
And cooling the sample subjected to intermediate pre-aging to room temperature, and then performing multi-pass rolling, wherein the controlled reduction of each pass is 10%, and the total pressure is 60%.
(5) Final aging of
And carrying out final aging treatment on the pre-aged variable temperature rolled alloy, wherein the aging temperature is 230 ℃, and the time is prolonged to 35h at most.
The change in electrical conductivity of the tested alloys, at which the initial rate of increase in electrical conductivity over time was faster, reached 10.21% IACS/h, the highest electrical conductivity reached 60.3% IACS, the time of aging to reach the highest electrical conductivity required 25h or so, corresponding to a yield strength of 159MPa, but a elongation at break of 16%, which was relatively low. In comprehensive comparison, the rolling process of adjusting the temperature-variable rolling process to be cooled to room temperature for rolling also has excellent electric conductivity and mechanical properties, but the overall properties are slightly lower than those of the temperature-variable rolling process, and the fracture elongation is slightly lower. More importantly, the temperature-variable rolling is started after aging, and does not need to undergo a cooling waiting process, so that the production efficiency is higher.
The embodiments of the present invention are not limited to the embodiments described above, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and they are included in the scope of the present invention.
Claims (10)
1. A composite thermomechanical treatment method for regulating and controlling the conductivity and mechanical property of aluminum alloy is characterized in that: the method comprises the following steps:
1) Carrying out cold rolling deformation on the deformed aluminum alloy plate to obtain a cold-rolled plate;
2) Placing the cold-rolled sheet in a heat preservation device for heat preservation, and then rapidly cooling to obtain a supersaturated solid solution, namely a supersaturated solid solution sheet;
3) Placing the supersaturated solid solution state plate in a heat preservation device for heat preservation so as to finish intermediate pre-aging;
4) Directly carrying out variable temperature rolling on the alloy plate subjected to intermediate pre-aging;
5) Placing the alloy subjected to variable temperature rolling into a heat preservation device for heat preservation, thereby completing final aging;
the temperature for heat preservation in the step 2) is 510-530 ℃, and the time for heat preservation is 15-30 min;
the temperature for heat preservation in the step 3) is 200-240 ℃, and the time for heat preservation is 0.5-2 h;
the rolling total reduction of the variable temperature rolling in the step 4) is 50-70%.
2. The composite thermomechanical treatment method for regulating and controlling the conductivity and mechanical properties of an aluminum alloy according to claim 1, wherein: the reduction of the cold rolling deformation in the step 1) is 10-20%.
3. The composite thermomechanical treatment method for regulating and controlling the conductivity and mechanical properties of an aluminum alloy according to claim 1, wherein: the temperature of the final aging in the step 5) is 210-240 ℃.
4. The composite thermomechanical treatment method for regulating and controlling the conductivity and mechanical properties of an aluminum alloy according to claim 1, wherein: the variable-temperature rolling in the step 4) is that the alloy plate which finishes the intermediate pre-aging is directly rolled without cooling, and the temperature is gradually reduced in the rolling process, namely the alloy plate which finishes the intermediate pre-aging is rolled for multiple times in the natural cooling process;
the rolling is multi-pass rolling, and the rolling reduction of each pass is 5-15%.
5. The composite thermomechanical treatment method for regulating and controlling the conductivity and the mechanical property of the aluminum alloy according to claim 1, wherein the method comprises the following steps: the cold rolling deformation refers to cold rolling deformation of the plate at room temperature;
the rapid cooling is cooling with room temperature water.
6. The composite thermomechanical treatment method for regulating and controlling the conductivity and mechanical properties of an aluminum alloy according to claim 1, wherein:
the wrought aluminum alloy plate in the step 1) is obtained by hot rolling, and is specifically obtained by casting a billet, performing homogenization heat treatment and performing high-temperature hot rolling on the wrought aluminum alloy.
7. The composite thermomechanical treatment method for regulating and controlling conductivity and mechanical properties of an aluminum alloy according to claim 6, wherein: the temperature of the high-temperature hot rolling is 450-500 ℃; the temperature of the homogenization heat treatment is 550-580 ℃, and the time is 7-9 h.
8. The composite thermomechanical treatment method for regulating and controlling the conductivity and mechanical properties of an aluminum alloy according to claim 1, wherein: the heat preservation time in the step 5) is 1-35 h;
in the step (1), the cold rolling is to naturally cool the alloy plate after hot rolling to room temperature and then carry out cold rolling.
9. An aluminium alloy obtainable by the method of any one of claims 1 to 8.
10. Use of an aluminium alloy according to claim 9, wherein: the aluminum alloy is used in the field of conductive busbars.
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