CN117305670B - 6000 series aluminum alloy plate with high baking strength and preparation method thereof - Google Patents
6000 series aluminum alloy plate with high baking strength and preparation method thereof Download PDFInfo
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- 229910000838 Al alloy Inorganic materials 0.000 title claims abstract description 57
- 238000002360 preparation method Methods 0.000 title claims abstract description 11
- 238000001816 cooling Methods 0.000 claims abstract description 109
- 238000010791 quenching Methods 0.000 claims abstract description 46
- 230000000171 quenching effect Effects 0.000 claims abstract description 45
- 238000005097 cold rolling Methods 0.000 claims abstract description 41
- 238000000034 method Methods 0.000 claims abstract description 29
- 239000012535 impurity Substances 0.000 claims abstract description 25
- 238000005266 casting Methods 0.000 claims abstract description 22
- 238000005098 hot rolling Methods 0.000 claims abstract description 18
- 230000032683 aging Effects 0.000 claims abstract description 16
- 238000004321 preservation Methods 0.000 claims description 41
- 238000005096 rolling process Methods 0.000 claims description 41
- 238000000137 annealing Methods 0.000 claims description 40
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 36
- 239000000243 solution Substances 0.000 claims description 35
- 238000007670 refining Methods 0.000 claims description 21
- 239000006104 solid solution Substances 0.000 claims description 21
- 238000007872 degassing Methods 0.000 claims description 20
- 238000002844 melting Methods 0.000 claims description 20
- 230000008018 melting Effects 0.000 claims description 20
- 239000003973 paint Substances 0.000 claims description 19
- 230000009467 reduction Effects 0.000 claims description 19
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 18
- 229910052786 argon Inorganic materials 0.000 claims description 18
- 238000001914 filtration Methods 0.000 claims description 18
- 239000001257 hydrogen Substances 0.000 claims description 18
- 229910052739 hydrogen Inorganic materials 0.000 claims description 18
- 230000008569 process Effects 0.000 claims description 17
- 239000000463 material Substances 0.000 claims description 15
- 238000004519 manufacturing process Methods 0.000 claims description 14
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 10
- 238000005507 spraying Methods 0.000 claims description 8
- 238000004364 calculation method Methods 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims description 3
- 238000002156 mixing Methods 0.000 claims description 2
- 239000002966 varnish Substances 0.000 description 33
- 239000000956 alloy Substances 0.000 description 22
- 230000001276 controlling effect Effects 0.000 description 22
- 229910045601 alloy Inorganic materials 0.000 description 20
- 230000000052 comparative effect Effects 0.000 description 20
- 238000009749 continuous casting Methods 0.000 description 19
- 238000005520 cutting process Methods 0.000 description 19
- 238000003801 milling Methods 0.000 description 17
- 239000000155 melt Substances 0.000 description 16
- 238000012360 testing method Methods 0.000 description 9
- 238000009776 industrial production Methods 0.000 description 8
- 230000000694 effects Effects 0.000 description 5
- 238000011156 evaluation Methods 0.000 description 5
- 238000012827 research and development Methods 0.000 description 4
- 230000007797 corrosion Effects 0.000 description 3
- 238000005260 corrosion Methods 0.000 description 3
- 238000011161 development Methods 0.000 description 3
- 230000018109 developmental process Effects 0.000 description 3
- 241000870659 Crassula perfoliata var. minor Species 0.000 description 2
- 229910017639 MgSi Inorganic materials 0.000 description 2
- 238000005452 bending Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000009957 hemming Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 238000001073 sample cooling Methods 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 238000010960 commercial process Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000007688 edging Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 238000000265 homogenisation Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000002932 luster Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 239000011856 silicon-based particle Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 230000035882 stress Effects 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
- 235000013619 trace mineral Nutrition 0.000 description 1
- 239000011573 trace mineral Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D29/00—Superstructures, understructures, or sub-units thereof, characterised by the material thereof
- B62D29/008—Superstructures, understructures, or sub-units thereof, characterised by the material thereof predominantly of light alloys, e.g. extruded
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
- B05D3/02—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by baking
- B05D3/0254—After-treatment
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/06—Making non-ferrous alloys with the use of special agents for refining or deoxidising
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C21/00—Alloys based on aluminium
- C22C21/02—Alloys based on aluminium with silicon as the next major constituent
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C21/00—Alloys based on aluminium
- C22C21/06—Alloys based on aluminium with magnesium as the next major constituent
- C22C21/08—Alloys based on aluminium with magnesium as the next major constituent with silicon
-
- 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
-
- 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
- C22F1/043—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys with silicon as the next major constituent
-
- 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
- C22F1/047—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys with magnesium as the next major constituent
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
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- Combustion & Propulsion (AREA)
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- Metal Rolling (AREA)
Abstract
The invention provides a 6000 series aluminum alloy plate with high baking strength and a preparation method thereof. The plate comprises the following components in percentage by mass: 0.7-1.5 wt% of Si, 0.25-1.2 wt% of Mg, less than or equal to 0.2wt% of Cu, less than or equal to 0.2wt% of Mn, less than or equal to 0.10wt% of Cr, less than or equal to 0.25wt% of Zn, less than or equal to 0.15wt% of Ti, less than or equal to 0.5wt% of Fe, and the balance of Al and unavoidable impurities, wherein the content of each impurity is less than 0.05wt%. The method comprises the following steps: casting, homogenizing treatment, hot rolling treatment, cold rolling treatment, solution treatment, quenching cooling, straightening treatment, pre-ageing treatment and baking finish treatment.
Description
Technical Field
The invention relates to the technical field of aluminum alloy, in particular to a 6000 series aluminum alloy plate with high baking strength and a preparation method thereof.
Background
With the rapid development of the automobile industry, the contradiction between energy and environmental protection and the automobile industry is increasingly prominent, and the light weight of automobiles becomes the main direction of the current automobile technology development. Aluminum alloy is increasingly used for automobile bodies with the advantages of small specific gravity, excellent corrosion resistance, good formability, weldability and easy recovery. Wherein 6000 series aluminum alloy is mainly used for the automobile body outer panel, 5000 series aluminum alloy is mainly used for structural members.
6000 series aluminum alloys for automotive body outer panels should have excellent press formability in order to meet various molding requirements of the body, and low initial yield strength is an important factor for ensuring press formability. Meanwhile, in order to ensure that the automobile body outer covering part has good dent resistance, 6000 series aluminum alloy must have higher baking strength. The higher the baking strength of the 6000 series aluminum alloy is, the lighter the weight of the material used for the automobile outer covering part is, so that the better the light weight effect is, the cost is reduced to a certain extent, the cost of the aluminum alloy part is more similar to that of the steel part, and the 6000 series aluminum alloy is popularized and applied in a large scale. At present, with the increase of sales of new energy electric vehicles year by year, research and development of 6000 series aluminum alloy plates are paid attention to material research and development institutions and automobile main engine factories. The lower initial yield strength can ensure the stamping formability, improve the baking varnish strength and obtain the good deformation resistance of the automobile outer covering part.
In recent years, a great deal of work is done around 6000 series vehicle body panels by some universities and scientific research institutions in China, and most researchers at present mainly focus on ageing process research in order to improve the baking varnish strength of the panels. For example, in terms of how to improve the bake hardenability of the alloy, patent CN201010283797.2 avoids indissolvable Mg by controlling the content of the main alloying elements Mg, si, cu 2 The formation of Si phase and excessive Si particles improves the forming performance of the material, ensures the content and proportion of Mg and Si phase, and ensures the bake hardening of the materialThe performance meets the use requirement; on the other hand, the contents of trace elements Fe and Mn are reasonably controlled so as to control the grain size and the like, thereby achieving the purpose of further improving the forming performance of the material. However, when the strength of the baking varnish is improved by regulating and controlling the Mg, si and Cu elements, the initial yield is increased, the sheet material is not beneficial to stamping and forming, and the Fe element is used as an impurity element, so that the formability of the material is greatly reduced once the casting link exceeds the standard. The patents CN201510048151.9, CN201310070872.0, CN202010950430.5 and the like, the pre-ageing process is adjusted to be two-stage pre-ageing, the first-stage pre-ageing is performed at a high temperature and short time, the second-stage pre-ageing is performed at a low temperature and long time, and good stamping formability is obtained before the aluminum alloy material is baked, but the two-stage pre-ageing process is not easy to realize in industrial production due to the first-stage pre-ageing, and the application of the two-stage pre-ageing process is limited to a certain extent. The patent 202010319069.6 obtains a specific deformed texture by controlling the hot rolling reduction and the finishing temperature, and finally obtains 6000 series aluminum alloy materials with excellent forming performance by combining the following two annealing processes and proper cold rolling times, but the baking varnish strengthening effect is not obvious.
Disclosure of Invention
The invention mainly aims to provide a 6000 series aluminum alloy plate with high baking strength and a preparation method thereof, so as to solve the defects in the prior art. The 6000 series aluminum alloy prepared by the method has low initial yield strength, excellent plate shape, excellent surface quality and edging performance, and also has high bake hardening performance.
The invention is realized by the following technical scheme.
A6000 series aluminum alloy plate for automobiles comprises the following components in percentage by mass: 0.7-1.5 wt% of Si, 0.25-1.2 wt% of Mg, less than or equal to 0.2wt% of Cu, less than or equal to 0.2wt% of Mn, less than or equal to 0.10wt% of Cr, less than or equal to 0.25wt% of Zn, less than or equal to 0.15wt% of Ti, less than or equal to 0.5wt% of Fe, and the balance of Al and unavoidable impurities, wherein the content of each impurity is less than 0.05wt%.
The preparation method of the plate comprises the following steps: casting, homogenizing treatment, hot rolling treatment, cold rolling treatment, solution treatment, quenching cooling, straightening treatment, pre-ageing treatment and baking finish treatment.
Further, the preparation method of the aluminum alloy plate comprises the following steps:
step S1, mixing the components of the plate according to the proportion, and casting into cast ingots after melting and refining;
step S2, homogenizing the cast ingot, controlling the heating temperature to be 540-580 ℃ and keeping the temperature for 6-10 hours;
step S3, performing hot rolling treatment on the cast ingot obtained in the step S2, controlling the initial rolling temperature to be 500-520 ℃, performing hot rolling to be 5-8mm, and controlling the final rolling temperature to be less than or equal to 280 ℃; then cold rolling to 0.8 mm-1.2 mm, intermediate annealing to 0.8 mm-1.2 mm, wherein the cold rolling reduction is 75% -90%, the intermediate annealing temperature is 450-500 ℃ and the time is 10-60s;
s4, carrying out solid solution treatment on the plate obtained in the step S3, wherein the heat preservation temperature is 550-560 ℃ and the heat preservation time is 60-120S;
step S5, quenching and cooling the plate obtained in step S4, wherein the cooling curve calculation formula of quenching and cooling is t=t 0 +Ae Rt Wherein T is the temperature, T 0 For a temperature after cooling of 25-50 ℃, a = solid solution temperature-temperature after cooling T 0 The R is the cooling intensity coefficient, and the unit is s -1 T is time, the unit is s, and the cooling intensity coefficient |R| is between 0.01 and 0.05;
s6, straightening the plate obtained in the step S5 by 0.3% -1% of deformation;
and S7, transferring the plate obtained in the step S6 to a temperature of 60-100 ℃ for heat preservation for 4-10 hours for pre-ageing treatment, and obtaining a finished plate.
And S8, pre-stretching the plate obtained in the step S7 by 2%, and then performing paint baking treatment, wherein the temperature of the paint baking treatment is 165-185 ℃, and the heat preservation time is 20-25min, so that the plate after the paint baking treatment is obtained.
In the above-described cooling curve calculation formula, R is a parameter obtained by performing exponential fitting according to an actual cooling curve, and its value is a negative value, and for convenience of expression in a physical sense, the absolute value thereof, i.e., |r|, is used as the cooling intensity coefficient.
Obtaining a quenching cooling curve by collecting samples with different properties, and obtaining sample cooling speed data according to an exponential formula T=T 0 +Ae Rt Exponential fitting was performed to determine an optimal cooling intensity coefficient |R| between 0.01 and 0.05.
The cooling rate of the industrial quenching furnace is controlled according to the combination of spray water and strong air cooling, and the cooling rate of the industrial quenching furnace is subjected to exponential fitting to determine that the cooling intensity coefficient |R| of the industrial quenching furnace is between 0.03 and 2.25.
In summary, the preferred commercial process of the present invention has a cooling intensity coefficient |R| of between 0.03 and 0.05.
The optimal cooling rate proposed by the invention is highly matched with industrial production equipment. When the cooling rate is too high, the plate shape is poor; when the cooling rate is too low, the plate varnish baking performance is poor, and the plastic layer on the roller is easy to damage after the plate is quenched Yu Wengao.
Further, the process conditions of the melting and refining are that a50 ppi filter disc is used for filtering, and an argon online degassing mode is adopted for degassing, so that the hydrogen content is controlled to be lower than 0.14ml/100g Al.
The process can improve the purity, uniformity and mechanical property of the aluminum alloy, and improve the surface quality of the aluminum alloy, so that the process is more suitable for manufacturing high-quality products.
Further, in step S1, an ingot is cast using a semi-continuous casting apparatus.
The semi-continuous casting equipment can control the thickness and quality of the aluminum alloy plate, rapidly and continuously produce the aluminum alloy plate, save energy and reduce production cost.
Further, quenching cooling was performed within 3s after the solution treatment.
The quenching cooling is carried out within 3s after solid solution, so that the bake hardening performance of the plate can be obviously improved, the principle is that the plate is cooled after solid solution, the time interval between solid solution and quenching is shortened, the problems of over high initial strength and low forming performance of alloy caused by precipitation of a large amount of MgSi phases are avoided, and meanwhile, the production efficiency is improved.
Further, quenching cooling is performed in step S5 by adjusting spraying and strong air cooling.
The specific optimal cooling rate of the invention is matched with strong wind, spraying and the like of the industrialized cooling mode, and the matched cooling mode can be provided for the industrialized production.
Further, the quenching cooling adopts a combination mode of 1-2 groups of water spraying and strong wind to carry out quenching cooling.
The invention can adopt a combination mode of 1-2 groups of water spraying and strong wind to quench and cool, thereby improving the operability of industrial production.
Further, straightening treatment with deformation of 0.3% -1% is carried out within 2min after quenching and cooling.
The straightening treatment can eliminate internal stress generated in the quenching process, improve the grain structure and the structure state of the plate, improve the stability and the reliability of the plate, and improve the overall quality and the appearance of the product.
Further, transferring to 60-100 ℃ after the straightening treatment for 4-10 hours for heat preservation after 5 minutes, and obtaining the finished plate.
The pre-ageing treatment is used for improving the performance and structural stability of the material in the manufacture of the aluminum alloy plate, and can fully diffuse and separate out solid solution phases and precipitated phases in the plate, so that the hardness, strength and corrosion resistance of the plate are improved. In addition, the pre-ageing treatment can also reduce deformation and cracks of the plate in the subsequent processing process, and improve the processing performance and the forming performance.
Further, the initial yield strength of the finished plate is lower than 90MPa, and the plate shape of the plate reaches a good level.
Further, the temperature of the baking varnish treatment is 165-185 ℃, and the heat preservation time is 20-25min.
Further, the post-baking yield strength of the plate after the baking varnish treatment is more than 200MPa, the grade of the surface varnish brush line is better than grade 2, and the curling grade is better than grade 2.
The baking varnish treatment can form a firm protective film on the surface of the aluminum alloy plate, effectively prevent the aluminum alloy plate from being damaged by oxidation, corrosion and other environments, enable the surface of the aluminum alloy plate to present rich colors and luster, improve the appearance texture of the product, increase the attractiveness of the product and prolong the service life of the product.
According to another aspect of the present invention, there is provided a 6000 series aluminum alloy sheet having high bake strength obtained according to the above-mentioned production method.
According to another aspect of the present invention there is provided the use of the aluminium alloy sheet material of the present invention in the manufacture of automotive body outer panels.
The technical scheme provided by the invention has the following beneficial effects:
the invention provides an exponential fit to the sample cooling rate data, wherein the exponential formula T=T 0 +Ae Rt (wherein T is the temperature, T 0 For a temperature after cooling of 25-50 ℃, a = solid solution temperature-temperature after cooling T 0 The R is the cooling intensity coefficient, and the unit is s -1 T is time, the unit is s), the coincidence degree of the fitting curve and the cooling curve is high, and the optimal cooling intensity coefficient |R| can be defined based on exponential fitting data; the optimal cooling rate proposed by the invention is highly matched with industrial production equipment. When the cooling rate is too high, the plate shape is poor; when the cooling rate is too low, the plate varnish baking performance is poor, and the plastic layer on the roller is easy to damage after the plate is quenched Yu Wengao. The method has the advantages that the definite optimal cooling rate is matched with strong wind, spraying and the like of the industrialized cooling mode, the matched cooling mode can be provided for the industrialized production, the technical gap between material process research and development and the industrialized production is eliminated, and the operability of the industrialized production is improved. The cooling rates of different plate thicknesses which are clear in the invention can be suitable for any suitable 6000 series aluminum alloy plate, and data support is provided for researching the quenching cooling rate and performance of 6000 series aluminum alloy after solid solution is carried out, so that the digital degree of material research and development is improved.
In particular, the technical advancement of the invention is at least embodied in the following aspects:
(1) The invention has the advantages that the optimal cooling rate can obviously improve the baking hardening performance of the plate, the effect is far higher than that of natural cooling and water cooling, and the principle is that the optimal cooling rate can separate out some clusters which are easy to grow in baking varnish in the cooling process, so that more beta' phases required by baking varnish hardening are formed during baking varnish treatment, and the baking varnish hardening performance of the plate is obviously improved.
(2) The quenching cooling within 3s after solid solution can obviously improve the bake hardening performance of the plate, and the principle is that the plate begins to cool after solid solution, the time interval between solid solution and quenching is shortened, the problems of over high initial strength and low forming performance of alloy caused by precipitation of a large amount of MgSi phases are avoided, and meanwhile, the production efficiency is improved.
(3) The cooling rate control method provided by the invention has high matching degree with the technological parameters such as the spraying water quantity, the strong wind rotating speed and the like of the industrial continuous annealing furnace, has low operation technical requirements, is easier to implement on the spot of industrial production, shortens the matching shutdown debugging period of the industrial continuous annealing furnace process, and reduces the industrial production cost.
(4) The optimal cooling rate provided by the invention can realize accurate control by adjusting the spray water quantity, the strong wind rotating speed and the like in the industrial continuous annealing furnace, has low operation technical requirements, is easier to implement on the spot of industrial production, avoids a large number of experimental plates generated by process matching and debugging, reduces the material cost and simultaneously reduces the carbon emission of industrial production.
(5) The cooling rate control method provided by the invention improves the baking varnish strength, and simultaneously ensures that the comprehensive performances of excellent plate shape, material flanging, paint brush wires, formability and the like are not reduced.
The aluminum alloy plate provided by the invention has the advantages that the equilibrium state can generate more nano precipitated phases than the conventional 6000 series aluminum alloy, the baking hardening performance is higher than that of the conventional 6000 series aluminum alloy, the baking paint strength of the plate can be obviously improved on the premise of ensuring the lower initial yield strength of the plate, and meanwhile, the excellent plate shape, the edge covering performance and the surface quality are ensured. The plate obtained by the method has excellent mechanical property and surface quality, particularly has high bake hardening property and plate shape, does not increase the material cost, and is particularly suitable for high-strength automobile outer panel.
Detailed Description
It should be noted that, in the case of no conflict, the embodiments and features in the embodiments may be combined with each other. The present invention will be described in detail with reference to examples.
In the development process of the 6000 series aluminum alloy plate with high baking varnish strength for the automobile body outer covering, the preparation process is strictly controlled, so that the high baking hardening performance and the plate shape of the plate are realized on the premise of ensuring the low initial yield strength of the plate, and the method is better suitable for the automobile outer covering with high requirements on formability and strength.
Firstly, pure aluminum and various intermediate alloys are melted according to the proportion (Si is 0.7wt% -1.5wt%, mg is 0.25wt% -1.2wt%, cu is less than or equal to 0.2wt%, mn is less than or equal to 0.2wt%, cr is less than or equal to 0.10wt%, zn is less than or equal to 0.25wt%, ti is less than or equal to 0.15wt%, fe is less than or equal to 0.5wt%, and the balance is Al and unavoidable impurities, wherein the content of each impurity is less than 0.05wt%, and casting an ingot by using semi-continuous casting equipment after refining treatment.
And cutting the head and milling the surface of the cast ingot, then placing the cast ingot into a heat treatment furnace for homogenization treatment, and after the homogenized cast ingot is cooled to the initial rolling temperature and is kept for a period of time, starting hot rolling. And after the hot rolling is finished, carrying out cold rolling and intermediate annealing on the obtained hot rolled plate, then carrying out cold rolling again to the thickness of a final finished plate, and carrying out pre-ageing treatment on the obtained cold rolled plate after solution treatment and water quenching treatment to obtain the finished plate.
Hereinafter, examples of the present invention are given, and technical effects of the present invention can be further confirmed according to these examples. However, the examples are only preferred embodiments of the present invention, and the scope of the subject matter should not be construed as being limited thereto, and all technical solutions formed based on the technical concept of the present invention fall within the scope of the present invention.
Example 1
The aluminum alloy comprises the following components in percentage by mass: si:0.7wt%, mg:1.0wt%, cu:0.1wt%, mn:0.2wt%, zn:0.1wt%, fe:0.15wt% of Al and impurities with the content of less than 0.05wt%.
Melting the alloy according to the proportion, refining the melt (filtering by using a filter sheet with the aperture of 50ppi, carrying out online degassing by argon, controlling the hydrogen content to be 0.13ml/100g Al), and casting an ingot by using semi-continuous casting equipment; homogenizing the cast ingot after head cutting and face milling, wherein the homogenizing temperature is 560 ℃, and preserving heat for 8 hours; then cooling to 515 ℃ for initial rolling, rolling to 6mm, and finishing rolling at 270 ℃; cold rolling to 1.1mm, cold rolling reduction rate of 82%, intermediate annealing temperature of 485 ℃ and annealing time of 30s, then carrying out solution treatment, solution treatment temperature of 555 ℃, heat preservation time of 90s, cooling and quenching in 3s, straightening treatment with a cooling strength coefficient of |R|=0.03 with deformation of 0.5% in 1min after cooling, transferring the straightened plate to 80 ℃ for 8h at 3min, finally obtaining a T4P-state finished plate, carrying out 2% pre-stretching post-baking varnish treatment on the finished plate, and carrying out heat preservation time of 20min at 185 ℃ to obtain the post-baking varnish plate.
Example 2
The aluminum alloy comprises the following components in percentage by mass: si:0.85wt%, mg:0.75wt%, cu:0.15wt%, mn:0.2wt%, zn:0.15wt%, fe:0.18wt% of Al and impurities with the content of less than 0.05wt%.
Melting the alloy according to the proportion, refining the melt (filtering by using a filter sheet with the aperture of 50ppi, carrying out online degassing by argon, controlling the hydrogen content to be 0.13ml/100g Al), and casting an ingot by using semi-continuous casting equipment; homogenizing the cast ingot after head cutting and face milling, wherein the homogenizing temperature is 560 ℃, and preserving heat for 8 hours; then cooling to 510 ℃ for initial rolling, rolling to 5mm, and finishing rolling at 280 ℃; cold rolling to 0.9mm, cold rolling reduction rate of 82%, intermediate annealing temperature of 450 ℃ and annealing time of 60s, then carrying out solution treatment, solution treatment temperature of 560 ℃, heat preservation time of 75s, cooling and quenching in 2s, straightening treatment of 0.8% deformation in 1min, transferring the straightened plate to 75 ℃ for 10h at 4min, finally obtaining a T4P state finished plate, carrying out 2% prestretching and baking finish treatment on the finished plate, wherein the temperature of the baking finish treatment is 185 ℃, and the heat preservation time is 20min, thus obtaining the plate after baking finish.
Example 3
The aluminum alloy comprises the following components in percentage by mass: si:1.1wt%, mg:0.5wt%, cu:0.16wt%, mn:0.2wt%, zn:0.15wt%, fe:0.18wt% of Al and impurities with the content of less than 0.05wt%.
Melting the alloy according to the proportion, refining the melt (filtering by using a filter sheet with the aperture of 50ppi, carrying out online degassing by argon, controlling the hydrogen content to be 0.13ml/100g Al), and casting an ingot by using semi-continuous casting equipment; homogenizing the cast ingot after head cutting and face milling, wherein the homogenizing temperature is 560 ℃, and preserving heat for 8 hours; then cooling to 510 ℃ for initial rolling, rolling to 6mm, and finishing rolling at 270 ℃; cold rolling to 1mm, wherein the cold rolling reduction is 83%, the intermediate annealing temperature is 500 ℃ and the annealing time is 10s, then carrying out solution treatment, the solution treatment temperature is 560 ℃, the heat preservation time is 60s, cooling and quenching are carried out in 3s, the straightening treatment of the deformation of 0.7% is carried out in 1min, the straightening treated plate is transferred to the temperature of 85 ℃ for 6h at 5min, finally, the T4P-state finished plate is obtained, the finished plate is subjected to 2% pre-stretching post-baking varnish treatment, the temperature of the baking varnish treatment is 185 ℃, and the heat preservation time is 20min, thus obtaining the post-baking varnish plate.
Example 4
The aluminum alloy comprises the following components in percentage by mass: si:0.8wt%, mg:0.75wt%, cu:0.2wt%, mn:0.2wt%, zn:0.1wt%, fe:0.2wt% of Al and impurities with the content of less than 0.05wt%.
Melting the alloy according to the proportion, refining the melt (filtering by using a filter sheet with the aperture of 50ppi, carrying out online degassing by argon, controlling the hydrogen content to be 0.13ml/100g Al), and casting an ingot by using semi-continuous casting equipment; homogenizing the cast ingot after head cutting and face milling, wherein the homogenizing temperature is 560 ℃, and preserving heat for 8 hours; then cooling to 500 ℃ for initial rolling, rolling to 6mm, and finishing rolling at 260 ℃; cold rolling to 0.8mm, cold rolling reduction rate of 87%, intermediate annealing temperature of 490 ℃ and annealing time of 25s, then carrying out solution treatment, solid solution treatment temperature of 550 ℃, heat preservation time of 120s, cooling and quenching in 3s, straightening treatment of 0.6% deformation in 2min, transferring the straightened plate to 100 ℃ for 4h at 4min, finally obtaining a T4P state finished plate, carrying out 2% prestretching and baking varnish treatment on the finished plate, wherein the temperature of the baking varnish treatment is 185 ℃, and the heat preservation time is 20min, thus obtaining the plate after baking varnish.
Example 5
The aluminum alloy comprises the following components in percentage by mass: si:0.8wt%, mg:0.76wt%, cu:0.1wt%, mn:0.2wt%, zn:0.1wt%, fe:0.2wt% of Al and impurities with the content of less than 0.05wt%.
Melting the alloy according to the proportion, refining the melt (filtering by using a filter sheet with the aperture of 50ppi, carrying out online degassing by argon, controlling the hydrogen content to be 0.13ml/100g Al), and casting an ingot by using semi-continuous casting equipment; homogenizing the cast ingot after head cutting and face milling, wherein the homogenizing temperature is 560 ℃, and preserving heat for 8 hours; then cooling to 515 ℃ for initial rolling, rolling to 8mm, and finishing rolling at 260 ℃; cold rolling to 0.8mm, cold rolling reduction of 90%, intermediate annealing at 475 ℃ for 35s, solution treatment at 550 ℃ for 90s, cooling and quenching in 3s, straightening with a cooling strength coefficient of |R|=0.03 and a deformation of 0.8% in 2min, transferring the straightened plate to 85 ℃ for 8h at 5min, finally obtaining a T4P-state finished plate, pre-stretching the finished plate for 2% and baking at 185 ℃ for 20min, and obtaining the baked plate.
Example 6
The aluminum alloy comprises the following components in percentage by mass: si:0.8wt%, mg:0.75wt%, cu:0.1wt%, mn:0.2wt%, zn:0.1wt%, fe:0.2wt% of Al and impurities with the content of less than 0.05wt%.
Melting the alloy according to the proportion, refining the melt (filtering by using a filter sheet with the aperture of 50ppi, carrying out online degassing by argon, controlling the hydrogen content to be 0.13ml/100g Al), and casting an ingot by using semi-continuous casting equipment; homogenizing the cast ingot after head cutting and face milling, wherein the homogenizing temperature is 560 ℃, and preserving heat for 8 hours; then cooling to 515 ℃ for initial rolling, rolling to 8mm, and finishing rolling at 250 ℃; cold rolling to 1mm, wherein the cold rolling reduction is 87.5%, the intermediate annealing temperature is 465 ℃, the annealing time is 40s, then solution treatment is carried out, the solution treatment temperature is 555 ℃, the heat preservation time is 60s, cooling quenching is carried out in 3s, the cooling strength coefficient |R|=0.05, straightening treatment with the deformation of 1% is carried out in 1min, the straightened plate is transferred to the temperature of 90 ℃ for 5h at 2min, finally, the T4P-state finished plate is obtained, the finished plate is subjected to 2% pre-stretching post-baking treatment, the temperature of the baking treatment is 185 ℃, and the heat preservation time is 20min, thus obtaining the post-baking-paint plate.
Example 7
The aluminum alloy comprises the following components in percentage by mass: si:0.8wt%, mg:0.74wt%, cu:0.1wt%, mn:0.18wt%, zn:0.1wt%, fe:0.18wt% of Al and impurities with the content of less than 0.05wt%.
Melting the alloy according to the proportion, refining the melt (filtering by using a filter sheet with the aperture of 50ppi, carrying out online degassing by argon, controlling the hydrogen content to be 0.13ml/100g Al), and casting an ingot by using semi-continuous casting equipment; homogenizing the cast ingot after head cutting and face milling, wherein the homogenizing temperature is 580 ℃, and preserving heat for 6 hours; then cooling to 515 ℃ for initial rolling, rolling to 6mm, and finishing rolling at 250 ℃; cold rolling to 1mm, wherein the cold rolling reduction is 83%, the intermediate annealing temperature is 450 ℃, the annealing time is 50s, then solution treatment is carried out, the solution treatment temperature is 555 ℃, the heat preservation time is 90s, cooling quenching is carried out in 3s, the straightening treatment with the deformation of 0.5% is carried out in 1.5min, the plate after the straightening treatment is transferred to the temperature of 95 ℃ for 5h at 5min, finally the T4P-state finished plate is obtained, the final plate is subjected to 2% pre-stretching and then baking finish treatment, the baking finish treatment temperature is 185 ℃, and the heat preservation time is 20min, thus obtaining the plate after baking finish.
Example 8
The aluminum alloy comprises the following components in percentage by mass: si:0.8wt%, mg:0.74wt%, cu:0.1wt%, mn:0.2wt%, zn:0.1wt%, fe:0.2wt% of Al and impurities with the content of less than 0.05wt%.
Melting the alloy according to the proportion, refining the melt (filtering by using a filter sheet with the aperture of 50ppi, carrying out online degassing by argon, controlling the hydrogen content to be 0.13ml/100g Al), and casting an ingot by using semi-continuous casting equipment; homogenizing the cast ingot after head cutting and face milling, wherein the homogenizing temperature is 540 ℃, and preserving heat for 10 hours; then cooling to 515 ℃ for initial rolling, rolling to 6mm, and finishing rolling at 250 ℃; cold rolling to 1mm, wherein the cold rolling reduction is 83%, the intermediate annealing temperature is 485 ℃, the annealing time is 40s, then solution treatment is carried out, the solution treatment temperature is 555 ℃, the heat preservation time is 120s, cooling quenching is carried out in 3s, the straightening treatment with the deformation of 0.3% is carried out in 2min, the plate after the straightening treatment is moved to 85 ℃ for 8h at 1min, finally the T4P-state finished plate is obtained, 2% pre-stretching post-baking finish treatment is carried out on the finished plate, the temperature of the baking finish treatment is 185 ℃, and the heat preservation time is 20min, thus obtaining the plate after baking finish.
Comparative example 1
The aluminum alloy comprises the following components in percentage by mass: si:0.85wt%, mg:0.75wt%, cu:0.5wt%, mn:0.25wt%, zn:0.15wt%, fe:0.18wt% of Al and impurities with the content of less than 0.05wt%.
Melting the alloy according to the proportion, refining the melt (filtering by using a filter sheet with the aperture of 50ppi, carrying out online degassing by argon, controlling the hydrogen content to be 0.13ml/100g Al), and casting an ingot by using semi-continuous casting equipment; homogenizing the cast ingot after head cutting and face milling, wherein the homogenizing temperature is 560 ℃, and preserving heat for 8 hours; hot rolling to 6mm and final rolling temperature of 275 ℃; cold rolling to 1mm, wherein the cold rolling reduction is 83%, the intermediate annealing temperature is 485 ℃, the annealing time is 30s, then solution treatment is carried out, the solution treatment temperature is 555 ℃, the heat preservation time is 60s, water cooling quenching is carried out in 3s, the straightening treatment with the deformation of 0.5% is carried out in 1min, the plate after the straightening treatment is transferred to the temperature of 80 ℃ for 8h at 5min, finally the T4P-state finished plate is obtained, the finished plate is subjected to 2% pre-stretching post-baking varnish treatment, the temperature of the baking varnish treatment is 185 ℃, and the heat preservation time is 20min, thus obtaining the plate after baking varnish.
Comparative example 2
The aluminum alloy comprises the following components in percentage by mass: si:0.85wt%, mg:0.75wt%, cu:0.3wt%, mn:0.25wt%, zn:0.15wt%, fe:0.18wt% of Al and impurities with the content of less than 0.05wt%.
Melting the alloy according to the proportion, refining the melt (filtering by using a filter sheet with the aperture of 50ppi, carrying out online degassing by argon, controlling the hydrogen content to be 0.13ml/100g Al), and casting an ingot by using semi-continuous casting equipment; homogenizing the cast ingot after head cutting and face milling, wherein the homogenizing temperature is 560 ℃, and preserving heat for 8 hours; hot rolling to 6mm and final rolling temperature of 275 ℃; cold rolling to 1.1mm, wherein the cold rolling reduction is 82%, the intermediate annealing temperature is 490 ℃, the annealing time is 30s, then carrying out solution treatment, the solution treatment temperature is 555 ℃, the heat preservation time is 60s, cooling and quenching are carried out in 3s, the cooling strength coefficient |R|=2.00, then carrying out straightening treatment with the deformation of 0.8%, moving the plate after the straightening treatment to the temperature of 80 ℃ for 8h at 20min, finally obtaining a T4P-state finished plate, carrying out 2% pre-stretching post-baking varnish treatment on the finished plate, wherein the temperature of the baking varnish treatment is 185 ℃, and the heat preservation time is 20min, thus obtaining the plate after baking varnish.
Comparative example 3
The aluminum alloy comprises the following components in percentage by mass: si:0.85wt%, mg:0.75wt%, cu:0.5wt%, mn:0.25wt%, zn:0.15wt%, fe:0.18wt% of Al and impurities with the content of less than 0.05wt%.
Melting the alloy according to the proportion, refining the melt (filtering by using a filter sheet with the aperture of 50ppi, carrying out online degassing by argon, controlling the hydrogen content to be 0.13ml/100g Al), and casting an ingot by using semi-continuous casting equipment; homogenizing the cast ingot after head cutting and face milling, wherein the homogenizing temperature is 560 ℃, and preserving heat for 8 hours; hot rolling to 6mm and final rolling temperature of 275 ℃; cold rolling to 1mm, wherein the cold rolling reduction is 83%, the intermediate annealing temperature is 475 ℃, the annealing time is 40s, then solution treatment is carried out, the solution treatment temperature is 555 ℃, the heat preservation time is 60s, cooling quenching is carried out within 1min, the cooling strength coefficient |R|=0.08, straightening treatment of 0.5% deformation is carried out within 1min, the plate after straightening treatment is moved to 80 ℃ for 8h at 5min, finally the T4P-state finished plate is obtained, 2% pre-stretching post-baking treatment is carried out on the finished plate, the temperature of the baking treatment is 185 ℃, and the heat preservation time is 20min, thus obtaining the plate after baking.
Comparative example 4
The aluminum alloy comprises the following components in percentage by mass: si:0.85wt%, mg:0.75wt%, cu:0.5wt%, mn:0.25wt%, zn:0.15wt%, fe:0.18wt% of Al and impurities with the content of less than 0.05wt%.
Melting the alloy according to the proportion, refining the melt (filtering by using a filter sheet with the aperture of 50ppi, carrying out online degassing by argon, controlling the hydrogen content to be 0.13ml/100g Al), and casting an ingot by using semi-continuous casting equipment; homogenizing the cast ingot after head cutting and face milling, wherein the homogenizing temperature is 560 ℃, and preserving heat for 8 hours; hot rolling to 6mm and final rolling temperature of 275 ℃; cold rolling to 0.9mm, cold rolling reduction rate of 85%, intermediate annealing temperature of 490 ℃ and annealing time of 30s, then carrying out solution treatment, solution treatment temperature of 555 ℃, heat preservation time of 60s, cooling and quenching in 3s, straightening treatment with a cooling intensity coefficient of |R|=0.005 and a deformation of 0.8% in 1min, transferring the straightened plate to 80 ℃ for 8h at 5min, finally obtaining a T4P state finished plate, carrying out 2% prestretching on the finished plate, and carrying out paint baking treatment, wherein the temperature of the paint baking treatment is 185 ℃, and the heat preservation time is 20min, thus obtaining the plate after paint baking.
Comparative example 5
The aluminum alloy comprises the following components in percentage by mass: si:0.85wt%, mg:0.75wt%, cu:0.5wt%, mn:0.25wt%, zn:0.15wt%, fe:0.18wt% of Al and impurities with the content of less than 0.05wt%.
Melting the alloy according to the proportion, refining the melt (filtering by using a filter sheet with the aperture of 50ppi, carrying out online degassing by argon, controlling the hydrogen content to be 0.13ml/100g Al), and casting an ingot by using semi-continuous casting equipment; homogenizing the cast ingot after head cutting and face milling, wherein the homogenizing temperature is 560 ℃, and preserving heat for 8 hours; hot rolling to 6mm and final rolling temperature of 275 ℃; cold rolling to 0.9mm, cold rolling reduction rate of 85%, intermediate annealing temperature of 485 ℃ and annealing time of 30s, then carrying out solution treatment, solution treatment temperature of 555 ℃, heat preservation time of 60s, cooling and quenching in 3s, straightening treatment with a cooling intensity coefficient of |R|=1.5 and a deformation of 0.8% in 1min, transferring the straightened plate to 80 ℃ for 8h at 5min, finally obtaining a T4P state finished plate, carrying out 2% prestretching on the finished plate, and carrying out paint baking treatment, wherein the temperature of the paint baking treatment is 185 ℃, and the heat preservation time is 20min, thus obtaining the plate after paint baking.
Comparative example 6
The aluminum alloy comprises the following components in percentage by mass: si:0.85wt%, mg:0.75wt%, cu:0.5wt%, mn:0.25wt%, zn:0.15wt%, fe:0.18wt% of Al and impurities with the content of less than 0.05wt%.
Melting the alloy according to the proportion, refining the melt (filtering by using a filter sheet with the aperture of 50ppi, carrying out online degassing by argon, controlling the hydrogen content to be 0.13ml/100g Al), and casting an ingot by using semi-continuous casting equipment; homogenizing the cast ingot after head cutting and face milling, wherein the homogenizing temperature is 560 ℃, and preserving heat for 8 hours; hot rolling to 6mm and final rolling temperature of 275 ℃; cold rolling to 1.1mm, cold rolling reduction rate of 82%, intermediate annealing temperature of 490 ℃ and annealing time of 30s, then carrying out solution treatment, solution treatment temperature of 555 ℃, heat preservation time of 150s, cooling and quenching in 5s, straightening treatment with cooling intensity coefficient of |R|=0.01 and 1min of deformation of 1%, transferring the straightened plate to 80 ℃ for 4h at 2min, finally obtaining a T4P state finished plate, carrying out 2% prestretching post-baking finish treatment on the finished plate, wherein the temperature of the baking finish treatment is 185 ℃, and the heat preservation time is 20min, thus obtaining the plate after baking finish.
Comparative example 7
The aluminum alloy comprises the following components in percentage by mass: si:0.85wt%, mg:0.75wt%, cu:0.15wt%, mn:0.25wt%, zn:0.15wt%, fe:0.18wt% of Al and impurities with the content of less than 0.05wt%.
Melting the alloy according to the proportion, refining the melt (filtering by using a filter sheet with the aperture of 50ppi, carrying out online degassing by argon, controlling the hydrogen content to be 0.13ml/100g Al), and casting an ingot by using semi-continuous casting equipment; homogenizing the cast ingot after head cutting and face milling, wherein the homogenizing temperature is 560 ℃, and preserving heat for 8 hours; hot rolling to 6mm and final rolling temperature of 275 ℃; cold rolling to 1.0mm, cold rolling reduction rate of 83%, intermediate annealing temperature of 490 ℃ and annealing time of 30s, then carrying out solution treatment, solution treatment temperature of 555 ℃, heat preservation time of 60s, cooling and quenching in 5s, straightening treatment with cooling intensity coefficient of |R|=0.005 and 1min of deformation of 1%, transferring the straightened plate to 80 ℃ for 4h at 2min, finally obtaining a T4P state finished plate, carrying out 2% prestretching post-baking finish treatment on the finished plate, wherein the temperature of the baking finish treatment is 185 ℃, and the heat preservation time is 20min, thus obtaining the plate after baking finish.
Comparative example 8
The aluminum alloy comprises the following components in percentage by mass: si:0.85wt%, mg:0.75wt%, cu:0.15wt%, mn:0.25wt%, zn:0.15wt%, fe:0.18wt% of Al and impurities with the content of less than 0.05wt%.
Melting the alloy according to the proportion, refining the melt (filtering by using a filter sheet with the aperture of 50ppi, carrying out online degassing by argon, controlling the hydrogen content to be 0.13ml/100g Al), and casting an ingot by using semi-continuous casting equipment; homogenizing the cast ingot after head cutting and face milling, wherein the homogenizing temperature is 560 ℃, and preserving heat for 8 hours; hot rolling to 6mm and final rolling temperature of 275 ℃; cold rolling to 1.0mm, cold rolling reduction rate of 83%, intermediate annealing temperature of 490 ℃ and annealing time of 30s, then carrying out solution treatment, solution treatment temperature of 555 ℃, heat preservation time of 60s, cooling and quenching in 5s, straightening treatment with cooling intensity coefficient of |R|=2.5 and 1min of deformation of 1%, transferring the straightened plate to 80 ℃ for 4h at 2min, finally obtaining a T4P state finished plate, carrying out 2% prestretching post-baking finish treatment on the finished plate, wherein the temperature of the baking finish treatment is 185 ℃, and the heat preservation time is 20min, thus obtaining the plate after baking finish.
The compositions of the aluminum alloys of examples 1-8 and comparative examples 1-8 are shown in Table 1.
TABLE 1
The aluminum alloys of examples 1 to 8 and comparative examples 1 to 8 were subjected to the relevant performance test.
1. Mechanical property test:
after 7 days of standing the finished sheet obtained, the yield strength (R p0.2 ) Tensile strength of（R s ) Elongation (A) 50 ) Testing; after 2% pre-stretching, the plate was simulated by using a bath oil oven to bake paint at 185 ℃ for 20min, and then tested for tensile strength (R p0.2 /BH). All mechanical properties test samples were taken in the vertical rolling direction, the sample size was set forth in Table 2 using the recommended A50 tensile test of GB/T228.
2. Evaluation of plate shape:
and (3) taking a sample with the length of 1000mm and the width of the whole width of the plate along the rolling direction from the obtained finished plate, and carrying out plate type test on the sample. And measuring the warping height of the end part of the plate and the maximum transverse or longitudinal unevenness of the plate surface outside the end part, and recording the number of waves in the length range of each meter. The plate shape grade evaluation (the warp height of the end part is less than or equal to 5mm, the maximum transverse or longitudinal unevenness of the plate surface outside the end part is less than or equal to 2.5mm, the number of waves in each meter length is less than or equal to 3, the definition is excellent, the warp height of the end part is less than or equal to 10mm, the maximum transverse or longitudinal unevenness of the plate surface outside the end part is less than or equal to 5mm, the number of waves in each meter length is less than or equal to 7, the definition is excellent, and the rest is disqualification) is carried out according to the measurement results, and the test results are shown in Table 2.
3. Evaluation of hemming Performance:
a strip sample with a length of 250mm and a width of 30mm was cut from the finished sheet for hemming performance evaluation. And pre-stretching the sample by 10% along the length direction, then cutting a50 mm multiplied by 30mm rectangular sample, and then performing a 180-degree bending test by using a pressure head (r/t=0.6, r is the radius of the pressure head, t is the plate thickness), wherein the distance between supporting rollers is ensured to be 3.2-3.3 mm in the test process. Metallographic photographing and rating of the external surface after bending (grade 1: smooth surface, no microcrack and continuous necking; grade 2: slightly rough surface, no microcrack and continuous necking; grade 3: microcrack or continuous necking; grade 4: apparent cracking of the surface, wherein grades 1 and 2 were acceptable to automobile companies and grades 3 and 4 were unacceptable), the test results are shown in Table 2.
4. Evaluation of paint line strength:
and cutting a rectangular sample with the length of 250mm and the width of 35mm from the finished plate, evaluating the defects of the surface paint brush line and the orange peel, wherein the length direction of the sample is perpendicular to the rolling direction, and the width direction is along the rolling direction. The sample was pre-stretched 10% in the length direction and the panel surface was lightly polished with 320# sand and then evaluated for the panel surface paint line strength (grade 1: no white streak on the surface, grade 2: discontinuous white streak on the surface, grade 3: continuous white streak on the surface, where grades 1 and 2 were acceptable to automobile companies and grade 3 were unacceptable), and the test results are shown in table 2.
TABLE 2
As can be seen from Table 2, the yield strength of the plates of examples 1-8 is kept at 85-90 MPa after the plates are parked for 7 days, and the elongation is more than or equal to 26%, so that the punching requirements of the plates are met; after the plate is subjected to 2% prestretching and +185 ℃ for 20min simulated baking varnish, the yield strength is greater than 215MPa, and the plate can be used as a high-strength automobile outer covering part. In the comparative examples, however, the following results were obtained in accordance with comparative examples 1 to 6 because the requirements of the present invention were not satisfied:
A. comparative example 1 coarse Mg precipitated due to the excessively high hot-rolling finishing temperature 2 Si is insufficient in solid solution during solid solution treatment, hardening effect of the plate after baking is insufficient, and yield strength after baking is low; the cooling rate is too high, and the plate shape of the plate is unqualified;
B. in comparative example 2, the transfer time after solid solution is too long, and clusters which are unfavorable for later baking and hardening are precipitated on the plate, so that the yield strength after baking varnish is low; the cooling rate is too high, and the plate shape of the plate is unqualified; the flanging performance of the plate is also lower than 2 levels, and the requirements are not met.
C. In comparative example 3, the initial yield strength of the plate is too high due to the fact that the cooling strength coefficient is too high, namely the quenching speed after solid solution is too high, the forming performance of the material is poor, and the bake hardening performance is low;
D. in comparative example 4, the cooling strength coefficient is too low, namely, the quenching speed after solid solution is slow, so that the baking hardening performance of the plate is poor;
E. in the comparative example 5, the initial yield strength of the plate is too high due to the too high quenching and cooling strength coefficient, the flanging performance is worst, the baking varnish hardening performance is poor, the plate warpage is obvious, the wave appears, and the plate shape is unqualified;
F. in comparative example 6, the cooling speed after solid solution is too slow, the initial yield strength of the plate is too low, the paint line performance is the worst, and the baking paint hardening performance is poor due to the overlong solid solution time;
G. comparative example 7 has a composition close to the range of the present invention, but the cooling rate is significantly too slow, resulting in poor bake hardenability of the sheet;
H. comparative example 8 was close to the range of the present invention, but the cooling rate was significantly too fast, resulting in significant warpage of the sheet, occurrence of waves, and failure of the sheet shape.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A method for preparing 6000 series aluminum alloy plates with high baking strength, which is characterized in that the plates comprise the following components in percentage by mass: 0.7-1.5 wt% of Si, 0.25-1.2 wt% of Mg, less than or equal to 0.2wt% of Cu, less than or equal to 0.2wt% of Mn, less than or equal to 0.10wt% of Cr, less than or equal to 0.25wt% of Zn, less than or equal to 0.15wt% of Ti, less than or equal to 0.5wt% of Fe, and the balance of Al and unavoidable impurities, wherein the content of each impurity is less than 0.05wt%; the method comprises the following steps:
step S1, mixing the components of the plate according to the proportion, and casting into cast ingots after melting and refining;
step S2, homogenizing the cast ingot, controlling the heating temperature to be 540-580 ℃ and keeping the temperature for 6-10 hours;
step S3, performing hot rolling treatment on the cast ingot obtained in the step S2, controlling the initial rolling temperature to be 500-520 ℃, performing hot rolling to be 5-8mm, and controlling the final rolling temperature to be less than or equal to 280 ℃; then cold rolling treatment is carried out, intermediate annealing is carried out to 0.8 mm-1.2 mm, the cold rolling reduction is 75% -90%, the temperature of the intermediate annealing is 450-500 ℃, and the time is 10-60s;
s4, carrying out solid solution treatment on the plate obtained in the step S3, wherein the heat preservation temperature is 535-560 ℃ and the heat preservation time is 60-120S;
step S5, quenching and cooling the plate obtained in the step S4, wherein the cooling curve calculation formula of the quenching and cooling is T=T 0 +Ae Rt Wherein T is the temperature, T 0 For a temperature after cooling of 25-50 ℃, a = solid solution temperature-temperature after cooling T 0 The R is the cooling intensity coefficient, and the unit is s -1 T is time, the unit is s, and the cooling intensity coefficient |R| is between 0.01 and 0.05;
s6, straightening the plate obtained in the step S5 by 0.3% -1.0% of deformation;
s7, transferring the plate obtained in the step S6 to a temperature of 60-100 ℃ for heat preservation for 4-10 hours for pre-ageing treatment to obtain a finished plate;
and S8, pre-stretching the plate obtained in the step S7 by 2%, and then performing paint baking treatment, wherein the temperature of the paint baking treatment is 165-185 ℃, and the heat preservation time is 20-25min, so that the plate after the paint baking treatment is obtained.
2. The preparation method according to claim 1, wherein the process condition of the melting and refining is that a50 ppi filter disc is used for filtering, and the degassing is performed in an argon online degassing mode, so that the hydrogen content is controlled to be lower than 0.14ml/100g Al.
3. The production method according to claim 1 or 2, characterized in that the quenching cooling is performed within 3s after the solution treatment.
4. The method according to claim 1 or 2, wherein quenching cooling is performed by adjusting water spraying and strong air cooling in step S5.
5. The method according to claim 1 or 2, wherein in step S5, quenching cooling is performed by a combination of water spraying and forced air cooling in groups 1-2.
6. The method according to claim 1 or 2, characterized in that the straightening treatment is performed with a deformation of 0.3% -1% within 2min after the quenching.
7. The preparation method according to claim 1 or 2, wherein the pre-ageing treatment is carried out by transferring to a temperature of 60-100 ℃ for 4-10 hours in 5min after the straightening treatment, and a finished plate is obtained.
8. The preparation method according to claim 1 or 2, wherein the baking finish treatment is carried out at a temperature of 165-185 ℃ for a heat preservation time of 20-25min.
9. 6000 series aluminium alloy sheet with high bake strength, characterized in that it is obtained according to the production method of any one of claims 1 to 8.
10. Use of the aluminium alloy sheet material according to claim 9 for manufacturing automotive body outer panels.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2015010259A (en) * | 2013-06-28 | 2015-01-19 | 国立大学法人横浜国立大学 | Aluminum alloy sheet |
| CN114058885A (en) * | 2021-11-16 | 2022-02-18 | 中铝材料应用研究院有限公司 | 6XXX series aluminum alloy plate and preparation method and welding method thereof |
| CN114351016A (en) * | 2021-12-30 | 2022-04-15 | 广东和胜工业铝材股份有限公司 | Coarse-grain aluminum alloy and preparation method and application thereof |
| CN115198073A (en) * | 2022-07-25 | 2022-10-18 | 中铝瑞闽股份有限公司 | Preparation method of 6xxx aluminum alloy plate through homogenization and heating separation |
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| FR3076837B1 (en) * | 2018-01-16 | 2020-01-03 | Constellium Neuf-Brisach | PROCESS FOR THE MANUFACTURE OF THIN SHEETS OF HIGH-SURFACE ALUMINUM 6XXX ALLOY |
| KR20210003196A (en) * | 2018-04-24 | 2021-01-11 | 콘스텔리움 진겐 게엠베하 | 6XXX aluminum alloy for extrusion with excellent impact performance and high yield strength, and its manufacturing method |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2015010259A (en) * | 2013-06-28 | 2015-01-19 | 国立大学法人横浜国立大学 | Aluminum alloy sheet |
| CN114058885A (en) * | 2021-11-16 | 2022-02-18 | 中铝材料应用研究院有限公司 | 6XXX series aluminum alloy plate and preparation method and welding method thereof |
| CN114351016A (en) * | 2021-12-30 | 2022-04-15 | 广东和胜工业铝材股份有限公司 | Coarse-grain aluminum alloy and preparation method and application thereof |
| CN115198073A (en) * | 2022-07-25 | 2022-10-18 | 中铝瑞闽股份有限公司 | Preparation method of 6xxx aluminum alloy plate through homogenization and heating separation |
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