A high-strength 6-series aluminum alloy for photovoltaic aluminum materials and a preparation method thereof

Abstract

The present invention provides a high-strength 6-series aluminum alloy for photovoltaic aluminum materials and a preparation method thereof. The 6-series aluminum alloy includes the following components by mass percentage: Mg: 0.8-1.0%, Si: 0.5-0.7%, Cu: 0.2-0.3%, Cr: 0.1-0.25%, Mn: 0.3-0.5%, Ti: 0.02-0.04%, Zn: 0.1-0.25%, Fe≤0.5%, and the balance is Al and inevitable impurity elements. Advantages of the present invention: The aluminum alloy profile prepared by the present invention has a significant improvement in strength relative to conventional 6061 alloy, with a tensile strength of more than 320Mpa and a yield strength of 290Mpa; the grain grade is high, and almost no coarse grain structure is produced, and the thickness of the coarse grain layer is within 0.3mm; the turning performance is excellent, and there will be no sticking knife or wire wrapping knife phenomenon, and at the same time, it can effectively avoid the increase in extrusion deformation resistance caused by the increase of Si and Mg elements, thereby ensuring the extrusion efficiency.

Description

[Technical field]

[0001] The present invention relates to the technical field of aluminum alloys, and in particular to a high-strength 6-series aluminum alloy for photovoltaic aluminum materials and a preparation method thereof. [Background technology]

[0002] 6061 alloy is one of the most commonly used alloys in the field of industrial aluminum profiles and is widely used in photovoltaic aluminum materials, etc. At present, the composition of conventional 6061 alloy (national standard GBT 3190-2008) is: Mg: 0.8-1.2%, Si: 0.4-0.8%, Cu: 0.15-0.4%, Cr: 0.04-0.35%, Mn≤0.15%, Ti≤0.15%, Zn≤0.25%, Fe≤0.7%, and the balance is Al and unavoidable impurity elements. It is a medium-strength aluminum alloy with a tensile strength of about 275Mpa and a yield strength of about 245Mpa. Among them, Mg, Si, Cu and Cr are the main strengthening elements actively added, and Mn, Ti, Zn and Fe are all non-actively added elements. However, existing 6061 alloy extruded products (especially solid materials such as bars) are prone to coarse grain rings or excessively thick coarse grain layers. They are also prone to sticking to the tool or wire entanglement during lathe turning, making it difficult to meet customer requirements (high strength, easy turning, and no coarse grains).

[0003] At present, in order to improve the strength of 6061 alloy profiles, the content of main strengthening elements such as Mg, Si, and Cu is usually increased to enhance the precipitation strengthening effect during the aging process. However, the solid solution strengthening effect brought about by the increase in the content of Mg, Si, and Cu will increase the resistance to extrusion deformation (i.e., reduce the extrusion formability of the alloy), and the grains are prone to grow and produce coarse grains during the extrusion process, and the extrusion efficiency is low. Therefore, it is urgent to provide an aluminum alloy that can improve both strength and extrusion efficiency and turning performance. [Summary of the invention]

[0004] The technical problem to be solved by the present invention is to provide a high-strength 6 series aluminum alloy for photovoltaic aluminum materials and a preparation method thereof, which can not only improve the strength, but also improve the extrusion efficiency and turning performance, and almost no coarse grains will be produced.

[0005] The present invention is achieved in that:

[0006] In a first aspect, a high-strength 6-series aluminum alloy for photovoltaic aluminum material, the 6-series aluminum alloy comprises the following components in terms of mass percentage:

[0007] Mg: 0.8-1.0%, Si: 0.5-0.7%, Cu: 0.2-0.3%, Cr: 0.1-0.25%, Mn: 0.3-0.5%, Ti: 0.02-0.04%, Zn: 0.1-0.25%, Fe≤0.5%, the balance is Al and unavoidable impurity elements.

[0008] Furthermore, the tensile strength of the 6 series aluminum alloy is ≥320 MPa, the yield strength is ≥290 MPa, and the thickness of the coarse grain layer is <0.3 mm.

[0009] Furthermore, among the inevitable impurity elements, the total content of the impurities is less than 0.15%, and the content of each impurity element is less than 0.05%.

[0010] In a second aspect, a method for preparing a high-strength 6-series aluminum alloy for photovoltaic aluminum materials is provided, the preparation method comprising the following steps:

[0011] Ingredients: Provide raw materials according to the composition ratio of 6 series aluminum alloy;

[0012] Melting and casting: Melting and casting the raw materials to form aluminum alloy ingots, and homogenizing the aluminum alloy ingots, including heating and cooling the aluminum alloy ingots in stages;

[0013] Extrusion molding: Extrusion molding of aluminum alloy ingots to obtain aluminum alloy profiles;

[0014] Aging treatment: Double-stage aging treatment is performed on aluminum alloy profiles.

[0015] Furthermore, the stepwise heating and cooling of the aluminum alloy ingot specifically includes:

[0016] The first stage: heating the aluminum alloy ingot to 300-320℃ and keeping it warm for 6 hours;

[0017] The second stage: heating the aluminum alloy ingot to 560-580℃ and keeping it warm for 4h;

[0018] The third stage: spray rapid cooling, cooling the aluminum alloy ingot to below 300°C at a cooling rate of 280°C / h or more;

[0019] The fourth stage: slow cooling after being taken out of the furnace. The aluminum alloy ingot is placed outside the furnace to cool naturally to room temperature.

[0020] Furthermore, the double-stage aging treatment of the aluminum alloy profile specifically includes:

[0021] The aluminum alloy profile is heated to 140-150°C and then kept at this temperature for 4 hours, and then heated to 180-190°C and then kept at this temperature for 4 hours, and the aluminum alloy profile is taken out of the furnace and naturally cooled to room temperature.

[0022] Furthermore, before extruding the aluminum alloy ingot, the method further includes: heating the aluminum alloy ingot after homogenization to 480-510° C. and keeping the temperature for 2-5 hours.

[0023] Furthermore, the extrusion molding of the aluminum alloy ingot is specifically as follows:

[0024] An extruder is used to extrude the heated aluminum alloy ingot, and ensure that the discharge temperature of the aluminum alloy profile reaches 510-540℃, wherein the extrusion barrel of the extruder needs to be preheated to 430-450℃, the extrusion die is preheated to 460-480℃ and kept warm for more than 3h, and the extruded aluminum alloy profile is treated with online strong air cooling or water cooling quenching.

[0025] Furthermore, in the process of melting and casting the raw materials to form aluminum alloy ingots, the component Ti is added online in the launder in the form of Al-Ti-B wire refiner in the final casting step.

[0026] By adopting the technical solution of the present invention, at least the following beneficial effects are achieved: by scientifically designing the composition of the alloy, adding Mn, Ti and Zn to the main strengthening elements, the grains can be effectively refined, the formation and migration of the grain boundaries can be inhibited during the online solid solution of the extrusion process, and the precipitation of the strengthening phase can be promoted during the subsequent aging treatment process, so as to achieve the goal of improving the strength of the extruded profile, and the modified needle-shaped Si phase and the Fe-rich phase can be refined to improve the turning performance. At the same time, by reasonably regulating the distribution of the low temperature range and the high temperature range of the aluminum alloy ingot during the homogenization treatment process, the precipitation of the coarse Mg-Si second phase caused by long-term high temperature can be effectively avoided, and by adopting different cooling rates of fast cooling in the high temperature zone and slow cooling in the low temperature zone, the aluminum alloy ingot can decompose the network-distributed second phase during the homogenization and heat preservation process, reduce the deformation resistance of the aluminum alloy ingot during the subsequent extrusion process, so that the extrusion efficiency will not be reduced or even improved, and the aluminum alloy ingot can be easily dissolved back into the aluminum matrix during the subsequent extrusion online quenching, which is conducive to obtaining a better precipitation strengthening effect during the final aging treatment. Finally, a two-stage aging treatment is adopted. The low-temperature aging in the first stage can shorten the width of the grain boundary non-precipitation zone, and at the same time increase the nucleation point of the precipitation phase in the second stage, and increase the density of the precipitation phase; the high-temperature aging in the second stage can make the strengthening phase rapidly nucleate on the basis of the first stage, and the strengthening phase is small and the number density is increased, which can effectively improve the strength of the aluminum alloy profile. Therefore, the aluminum alloy profile obtained by adopting the present invention has a significant improvement in strength compared with the conventional 6061 alloy, with a tensile strength of more than 320Mpa and a yield strength of 290Mpa; the grain grade is high, and almost no coarse grain structure is produced, and the thickness of the coarse grain layer is within 0.3mm; the turning performance is excellent, and there will be no sticking or wire wrapping phenomenon, and at the same time, it can effectively avoid the increase in extrusion deformation resistance caused by the increase of Si and Mg elements, thereby ensuring the extrusion efficiency.

Brief Description of the Drawings

[0027] The present invention will be further described below in conjunction with embodiments with reference to the accompanying drawings.

[0028] Figure 1 This is a microstructure diagram of the ingot after the homogenization process of the present invention (OM, 1000 times);

[0029] Figure 2 This is the microstructure of the ingot after the traditional homogenization process (OM, 500 times);

[0030] Figure 3 is the grain structure diagram of the aluminum alloy profile obtained in Example 1 of the present invention (100 times);

[0031] Figure 4 This is the grain structure diagram of the aluminum alloy profile obtained in Comparative Example 1 of the present invention (100 times);

[0032] Figure 5 This is a microstructure diagram (TEM, 100,000 times) of an aluminum alloy profile after double-stage aging treatment according to the present invention;

[0033] Figure 6 This is the microstructure diagram of the aluminum alloy profile after traditional aging process (TEM, 100,000 times). [Specific implementation method]

[0034] The specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the specific embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to enable the scope of the present invention to be fully communicated to those skilled in the art.

[0035] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" is an open term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present invention, but the description is based on the general principles of the specification and is not intended to limit the scope of the present invention. The scope of protection of the present invention shall be determined by the attached claims.

[0036] The present invention discloses a high-strength 6-series aluminum alloy for photovoltaic aluminum materials, wherein the 6-series aluminum alloy comprises the following components in terms of mass percentage:

[0037] Mg: 0.8-1.0%, Si: 0.5-0.7%, Cu: 0.2-0.3%, Cr: 0.1-0.25%, Mn: 0.3-0.5%, Ti: 0.02-0.04%, Zn: 0.1-0.25%, Fe≤0.5%, the balance is Al and unavoidable impurity elements. Among the unavoidable impurity elements, the total content of impurities is less than 0.15%, and the content of each impurity element is less than 0.05%.

[0038] In order to improve the strength of the traditional 6061 alloy, the content of main strengthening elements such as Mg, Si, and Cu is usually increased. However, the solid solution strengthening effect brought about by the increase of Mg, Si, and Cu content will increase the resistance to extrusion deformation, and the grains are easy to grow and produce coarse grains during the extrusion process, and the extrusion efficiency is low. To this end, the present invention can achieve the goal of improving the strength of the extruded profile by adding Mn, Ti, and Zn to the main strengthening elements to promote the precipitation of strengthening phases, while avoiding the problem of increasing the extrusion deformation resistance and reducing the extrusion efficiency (i.e., increasing the extrusion production cost) due to increasing the Si and Mg content; in addition, it can effectively refine the grains and inhibit the growth of grains during the casting or extrusion process, thereby obtaining ingots and extruded profiles with ultrafine grains and improving the turning performance. Specifically, by adding microalloying elements such as Mn, Ti, and Zn to the main strengthening elements, the grains can be effectively refined, and the formation and migration of the grain boundaries can be inhibited during the online solid solution of the extrusion process. At the same time, the precipitation of the strengthening phase can be promoted during the subsequent aging treatment process, so as to achieve the goal of improving the strength of the extruded profile, and refine the modified needle-shaped Si phase and the Fe-rich phase, and improve its turning performance. In addition, because the present invention adds Mn, Ti, and Zn as the main strengthening elements, and Mn, Ti, and Zn are used as trace alloying elements, it is necessary to strictly control the content of Mn, Ti, and Zn (i.e., Mn is controlled at 0.3-0.5%, Ti is controlled at 0.02-0.04%, and Zn is controlled at 0.1-0.25%). If the content of Mn, Ti, and Zn is too high, the deformation resistance is large during extrusion, the extrusion difficulty increases, and the extrusion cost increases; if the content of Mn, Ti, and Zn is too low, the number of alloy strengthening phases is insufficient, which will cause the product strength to be difficult to meet the requirements.

[0039] In the present invention, the tensile strength of the 6 series aluminum alloy is ≥320 MPa, the yield strength is ≥290 MPa, and the thickness of the coarse grain layer is <0.3 mm.

[0040] The present invention provides a method for preparing a high-strength 6-series aluminum alloy for photovoltaic aluminum materials, the preparation method comprising the following steps:

[0041] Ingredients: The raw materials are provided according to the composition ratio of 6 series aluminum alloy. The elements of the raw materials mainly include actively added Mg, Si, Cu, Cr, Mn, Ti, Zn and Al, as well as non-actively added Fe and some inevitable impurity elements.

[0042] Melting and casting: The raw materials are melted and cast to form aluminum alloy ingots, which specifically includes melting, stirring, refining, degassing, standing, slag cleaning and other operations. The specific process adopted is the conventional process in the industry (unless otherwise specified), so this part of the conventional process will not be described in detail; and the aluminum alloy ingot is homogenized, including heating and cooling the aluminum alloy ingot in stages;

[0043] In the smelting and casting step, the step of heating and cooling the aluminum alloy ingot in stages specifically includes:

[0044] The first stage: the aluminum alloy ingot is heated to 300-320°C, and any value can be taken within the range of 300-320°C, and kept warm for 6 hours (i.e., 6 hours); in the first stage of heating, the temperature needs to be strictly controlled within the range of 300-320°C, otherwise, if the temperature of the first stage is too high, it will lead to long-term high temperature and cause the precipitation of coarse Mg-Si second phase; if the temperature of the first stage is too low, the homogenization effect will not be achieved;

[0045] The second stage: the aluminum alloy ingot is heated to 560-580°C, and the specific temperature can be any value within the range of 560-580°C, and kept warm for 4 hours;

[0046] The third stage: spray rapid cooling, cooling the aluminum alloy ingot to below 300°C at a cooling rate of 280°C / h or more;

[0047] The fourth stage: slow cooling after being taken out of the furnace. The aluminum alloy ingot is placed outside the furnace to cool naturally to room temperature.

[0048] The present invention can effectively avoid the precipitation of coarse Mg-Si second phase caused by long-term high temperature by reasonably regulating the distribution of low temperature interval and high temperature interval in the homogenization process of aluminum alloy ingot. At the same time, by adopting different cooling rates of fast cooling in high temperature zone and slow cooling in low temperature zone, the aluminum alloy ingot can decompose the second phase distributed in a network during the homogenization and heat preservation process; wherein, in the high temperature zone (above 300°C), a fast cooling method of high-pressure water mist cooling or water spraying is adopted, which can effectively inhibit the precipitation of coarse Mg-Si second phase; and in the low temperature zone (below 300°C), natural slow cooling outside the furnace is adopted to release the residual stress brought by the above-mentioned fast cooling process, and promote the formation of a large number of fine rod / band-shaped Mg-Si precipitation phases, so as to reduce the deformation resistance of the aluminum alloy ingot in the subsequent extrusion process as much as possible, so that the extrusion efficiency is not reduced or even improved, and at the same time, the aluminum alloy ingot is easily dissolved back into the aluminum matrix in the subsequent extrusion online quenching, which is conducive to obtaining a better precipitation strengthening effect in the final aging treatment;

[0049] In the smelting and casting step, during the process of melting and casting the raw materials to form an aluminum alloy ingot, the component Ti is added online in the launder in the form of an Al-Ti-B wire refiner in the final casting stage.

[0050] Extrusion molding: Extrusion molding of aluminum alloy ingots, including extrusion, online quenching, straightening and other operations, to obtain aluminum alloy profiles;

[0051] In the present invention, in order to realize the extrusion molding of the aluminum alloy ingot, before the aluminum alloy ingot is extruded, the method further includes: heating the aluminum alloy ingot after homogenization to 480-510°C, specifically any value can be taken within the range of 480-510°C, and keeping the temperature for 2-5h, specifically any value can be taken within the range of 2-5h;

[0052] In the extrusion molding step, the extrusion molding of the aluminum alloy ingot is specifically as follows: the heated aluminum alloy ingot is extruded by an extruder, and the discharge temperature of the aluminum alloy profile is ensured to reach 510-540°C, wherein the extrusion barrel of the extruder needs to be preheated to 430-450°C, and specifically any value can be taken within the range of 430-450°C, the extrusion die is preheated to 460-480°C and kept warm for more than 3 hours, and specifically any value can be taken within the range of 460-480°C, and the extruded aluminum alloy profile is treated by online strong air cooling or water cooling quenching, thereby achieving the superposition effect of extrusion work hardening and solid solution strengthening.

[0053] Aging treatment: Double-stage aging treatment is performed on aluminum alloy profiles;

[0054] In the aging treatment, the double-stage aging treatment of the aluminum alloy profile specifically includes:

[0055] The aluminum alloy profile is heated to 140-150°C and then kept warm for 4 hours, and the temperature can be arbitrarily selected within the range of 140-150°C. In the first stage of heating, if the temperature of the first stage is too high, the product will be easily over-aged, resulting in a decrease in product strength, while if the temperature of the first stage is too low, the product will be under-aged, resulting in the inability to increase product strength; then heated to 180-190°C and then kept warm for 4 hours, and the temperature can be arbitrarily selected within the range of 180-190°C, and the aluminum alloy profile is allowed to cool naturally to room temperature after being taken out of the furnace;

[0056] The present invention adopts a two-stage aging treatment, wherein the low-temperature aging in the first stage aims to shorten the width of the grain boundary non-precipitation zone, so as to suppress the widening of the grain boundary non-precipitation zone caused by the lack of vacancies / solute atoms near the grain boundary during the slow cooling process after extrusion, and at the same time increase the nucleation point of the precipitation phase in the second stage and increase the density of the precipitation phase; the high-temperature aging in the second stage is mainly to make the strengthening phase rapidly nucleate on the basis of the first stage, and the strengthening phase is small and the number density is increased, which can effectively improve the strength of the aluminum alloy profile.

[0057] In summary, the present invention can effectively refine the grains by scientifically designing the composition of the alloy and adding Mn, Ti and Zn to the main strengthening elements, and can inhibit the formation and migration of its grain boundaries during the online solid solution of the extrusion process, and can promote the precipitation of the strengthening phase during the subsequent aging treatment process, so as to achieve the goal of improving the strength of the extruded profile, and refine the modified needle-shaped Si phase and the Fe-rich phase, and improve its turning performance. At the same time, by reasonably regulating the distribution of the low temperature interval and the high temperature interval of the aluminum alloy ingot during the homogenization treatment process, the precipitation of the coarse Mg-Si second phase caused by long-term high temperature can be effectively avoided. By adopting different cooling rates of fast cooling in the high temperature zone and slow cooling in the low temperature zone, the aluminum alloy ingot can decompose the network-distributed second phase during the homogenization and heat preservation process, reduce the deformation resistance of the aluminum alloy ingot during the subsequent extrusion process, so that the extrusion efficiency will not be reduced or even improved, and the aluminum alloy ingot can be easily dissolved back into the aluminum matrix during the subsequent extrusion online quenching, which is conducive to obtaining a better precipitation strengthening effect during the final aging treatment. Finally, a two-stage aging treatment is adopted. The low-temperature aging in the first stage can shorten the width of the grain boundary non-precipitation zone, and at the same time increase the nucleation point of the precipitation phase in the second stage, and increase the density of the precipitation phase; the high-temperature aging in the second stage can make the strengthening phase rapidly nucleate on the basis of the first stage, and the strengthening phase is small and the number density is increased, which can effectively improve the strength of the aluminum alloy profile. Therefore, the aluminum alloy profile obtained by adopting the present invention has a significant improvement in strength compared with the conventional 6061 alloy, with a tensile strength of more than 320Mpa and a yield strength of 290Mpa; the grain grade is high, and almost no coarse grain structure is produced, and the thickness of the coarse grain layer is within 0.3mm; the turning performance is excellent, and there will be no sticking or wire wrapping phenomenon, and at the same time, it can effectively avoid the increase in extrusion deformation resistance caused by the increase of Si and Mg elements, thereby ensuring the extrusion efficiency.

[0058] The technical solution of the present invention is further described in detail below in conjunction with some specific embodiments and comparative examples:

[0059] Example 1

[0060] Ingredients: The composition ratio of 6 series aluminum alloy is Mg: 0.89%, Si: 0.61%, Cu: 0.25%, Cr: 0.18%, Mn: 0.41%, Ti: 0.029%, Zn: 0.21%, Fe: 0.15%, and the balance is Al and unavoidable impurity elements;

[0061] Melting and casting: The raw materials are melted and cast to form aluminum alloy ingots; the aluminum alloy ingots are first heated to 310°C and kept warm for 6 hours; then the aluminum alloy ingots are heated to 570°C and kept warm for 4 hours; then spray-cooled to cool the aluminum alloy ingots to 280°C at a cooling rate of 300°C / h; finally, the aluminum alloy ingots are placed outside the furnace to cool naturally to room temperature;

[0062] Extrusion molding: heat the aluminum alloy ingot after homogenization to 490℃ and keep it warm for 4h; use an extruder to extrude the heated aluminum alloy ingot and ensure that the discharge temperature of the aluminum alloy profile reaches 530℃. The extrusion barrel of the extruder needs to be preheated to 440℃, and the extrusion die needs to be preheated to 470℃ and kept warm for 4h;

[0063] Aging treatment: heat the aluminum alloy profile to 145℃ and keep it for 4 hours, then heat it to 185℃ and keep it for 4 hours, and let the aluminum alloy profile cool down naturally to room temperature after being taken out of the furnace.

[0064] Example 2

[0065] Ingredients: The composition ratio of 6 series aluminum alloy is Mg: 1.0%, Si: 0.7%, Cu: 0.3%, Cr: 0.25%, Mn: 0.5%, Ti: 0.04%, Zn: 0.25%, Fe: 0.5%, and the balance is Al and unavoidable impurity elements;

[0066] Melting and casting: The raw materials are melted and cast to form aluminum alloy ingots; the aluminum alloy ingots are first heated to 320°C and kept warm for 6 hours; then the aluminum alloy ingots are heated to 580°C and kept warm for 4 hours; then spray-cooled to cool the aluminum alloy ingots to 295°C at a cooling rate of 300°C / h; finally, the aluminum alloy ingots are placed outside the furnace to cool naturally to room temperature;

[0067] Extrusion molding: heat the aluminum alloy ingot after homogenization to 510℃ and keep it warm for 5h; use an extruder to extrude the heated aluminum alloy ingot and ensure that the discharge temperature of the aluminum alloy profile reaches 540℃. The extrusion barrel of the extruder needs to be preheated to 450℃, and the extrusion die needs to be preheated to 480℃ and kept warm for 4h;

[0068] Aging treatment: heat the aluminum alloy profile to 150℃ and keep it warm for 4 hours, then heat it to 190℃ and keep it warm for 4 hours, and let the aluminum alloy profile cool down naturally to room temperature after being taken out of the furnace.

[0069] Example 3

[0070] Ingredients: The composition ratio of 6 series aluminum alloy is Mg: 0.8%, Si: 0.5%, Cu: 0.2%, Cr: 0.1%, Mn: 0.3%, Ti: 0.02%, Zn: 0.1%, Fe: 0.05%, and the balance is Al and unavoidable impurity elements;

[0071] Melting and casting: The raw materials are melted and cast to form aluminum alloy ingots; the aluminum alloy ingots are first heated to 300°C and kept warm for 6 hours; then the aluminum alloy ingots are heated to 560°C and kept warm for 4 hours; then spray-cooled to cool the aluminum alloy ingots to 260°C at a cooling rate of 280°C / h; finally, the aluminum alloy ingots are placed outside the furnace to cool naturally to room temperature;

[0072] Extrusion molding: heat the aluminum alloy ingot after homogenization to 480℃ and keep it warm for 2h; use an extruder to extrude the heated aluminum alloy ingot and ensure that the discharge temperature of the aluminum alloy profile reaches 510℃. The extrusion barrel of the extruder needs to be preheated to 430℃, and the extrusion die needs to be preheated to 460℃ and kept warm for 3h;

[0073] Aging treatment: heat the aluminum alloy profile to 140℃ and keep it warm for 4 hours, then heat it to 180℃ and keep it warm for 4 hours, and let the aluminum alloy profile cool down naturally to room temperature after being taken out of the furnace.

[0074] Example 4

[0075] Ingredients: The composition ratio of 6 series aluminum alloy is Mg: 0.89%, Si: 0.61%, Cu: 0.25%, Cr: 0.18%, Mn: 0.41%, Ti: 0.029%, Zn: 0.21%, Fe: 0.15%, and the balance is Al and unavoidable impurity elements;

[0076] Melting and casting: The raw materials are melted and cast to form aluminum alloy ingots; the aluminum alloy ingots are first heated to 300°C and kept warm for 6 hours; then the aluminum alloy ingots are heated to 560°C and kept warm for 4 hours; then spray-cooled to cool the aluminum alloy ingots to 280°C at a cooling rate of 290°C / h; finally, the aluminum alloy ingots are placed outside the furnace to cool naturally to room temperature;

[0077] Extrusion molding: heat the aluminum alloy ingot after homogenization to 480℃ and keep it warm for 2h; use an extruder to extrude the heated aluminum alloy ingot and ensure that the discharge temperature of the aluminum alloy profile reaches 520℃. The extrusion barrel of the extruder needs to be preheated to 430℃, and the extrusion die needs to be preheated to 460℃ and kept warm for 3h;

[0078] Aging treatment: heat the aluminum alloy profile to 150℃ and keep it warm for 4 hours, then heat it to 190℃ and keep it warm for 4 hours, and let the aluminum alloy profile cool down naturally to room temperature after being taken out of the furnace.

[0079] Example 5

[0080] Ingredients: The composition ratio of 6 series aluminum alloy is Mg: 0.85%, Si: 0.54%, Cu: 0.23%, Cr: 0.13%, Mn: 0.35%, Ti: 0.022%, Zn: 0.18%, Fe: 0.12%, and the balance is Al and unavoidable impurity elements; the remaining steps are exactly the same as in Example 1.

[0081] Comparative Example 1

[0082] The difference from Example 1 is that: in the smelting and casting step, a conventional homogenization process is adopted (the aluminum alloy ingot is heated to 570°C and then kept warm for 8 hours, then taken out of the furnace and naturally cooled to room temperature); at the same time, a conventional aging process is adopted in the aging treatment step (the aluminum alloy profile is heated to 175°C and then kept warm for 8 hours, and then naturally cooled to room temperature); the rest of the contents are exactly the same as in Example 1.

[0083] Comparative Example 2

[0084] The difference from Example 1 is that in the batching step, conventional 6061 alloy composition is used, namely, Mg: 0.98%, Si: 0.73%, Cu: 0.28%, Cr: 0.16%, Mn: 0.02%, Ti: 0.012%, Zn: 0.002%, Fe: 0.13%; the rest of the content is exactly the same as in Example 1.

[0085] Comparative Example 3

[0086] The difference from Example 1 is that in the smelting and casting steps, a conventional homogenization process is adopted (the aluminum alloy ingot is heated to 570°C and then kept warm for 8 hours, then taken out of the furnace and naturally cooled to room temperature); the rest of the contents are exactly the same as in Example 1.

[0087] Comparative Example 4

[0088] The difference from Example 1 is that a conventional aging process is used in the aging treatment step (the aluminum alloy profile is heated to 175° C., kept warm for 8 hours, and then naturally cooled to room temperature); the rest of the contents are exactly the same as Example 1.

[0089] Comparative Example 5

[0090] The difference from Example 1 is that in the batching step, Mn: 0.7%, Ti: 0.12%, Zn: 0.30%; the rest of the contents are exactly the same as in Example 1.

[0091] Comparative Example 6

[0092] The difference from Example 1 is that in the batching step, Mn: 0.15%, Ti: 0.01%, Zn: 0.05%; the rest of the contents are exactly the same as in Example 1.

[0093] Specific parameter performance is detailed in Table 1 below:

[0094] Table 1 Performance table of embodiments and comparative examples

[0095]

[0096]

[0097] As shown in Table 1 above, the strength of the aluminum alloy profiles obtained in Examples 1 to 5 is significantly improved compared to the conventional 6061 alloy, the tensile strength is above 320Mpa, the yield strength is 290Mpa, and the grain grade is high, the thickness of the coarse grain layer is within 0.3mm, the turning performance is excellent, and the turning chips are in the form of powder without wire. While the aluminum alloy profiles obtained in Comparative Examples 1 to 6 can improve some performances to a certain extent, they are completely unable to achieve the technical effect of the present invention on the basis of improving tensile strength, yield strength and elongation, improving grain grade, reducing coarse grain layer thickness, ensuring turning performance, and not having sticking knife or wire wrapping knife phenomenon, while also ensuring extrusion efficiency. It can also be seen from Comparative Examples 5 and 6 that when the content of Mn, Ti, and Zn is too high, it will lead to large deformation resistance and difficulty in extrusion; and if the content of Mn, Ti, and Zn is too low, it will be difficult to meet the requirements, and the turning performance is poor and easy to wire. In addition, it can be clearly known from the above embodiments and comparative examples that the technical effect of the present invention is obtained under the joint action of alloy composition design, staged heating of the homogenization process, high-temperature rapid cooling and low-temperature slow cooling, and double-stage aging treatment. The technical effect cannot be achieved without any one of these links.

[0098] The present invention is further described below in conjunction with some microstructure diagrams:

[0099] See also Figure 1 and Figure 2 As shown, Figure 1 The microstructure diagram (OM, 1000 times) of the ingot after the homogenization process of the present invention (Example 1) is shown in FIG. Figure 2 The microstructure of the ingot after the conventional homogenization process (Comparative Example 1) (OM, 500 times). Figure 1It can be seen that after the homogenization process of the present invention is used, a large number of fine particle-shaped dispersed precipitates are formed, and the network-shaped second phase in the as-cast state has been decomposed in the above homogenization process to form a large number of fine particle-shaped precipitates, rather than coarse and irregular Mg2Si phases (such as Figure 2 As shown). The traditional homogenization process uses natural cooling, which has a slow cooling rate, causing the precipitated second phase to easily aggregate and grow, forming a coarse and irregular Mg2Si phase (as shown Figure 2 shown).

[0100] See also Figure 3 and Figure 4 As shown, Figure 3 The grain structure diagram of the aluminum alloy profile obtained in Example 1 of the present invention (100 times), Figure 4 This is the grain structure diagram (100 times) of the aluminum alloy profile obtained in Comparative Example 1 of the present invention. Figure 3 The grain grade in the Figure 4 The grains of the aluminum alloy profiles are obviously refined. It can be seen that by actively adding appropriate amounts of Mn, Ti and Zn, the grains can be effectively refined and the growth of grains in subsequent homogenization and extrusion processes can be inhibited, thereby obtaining ultra-fine grain aluminum alloy profiles and improving the turning performance. The aluminum alloy profiles without active addition of Mn, Ti and Zn have a grain grade of about 5 (such as Figure 4 As shown), its grain size is larger than that of active addition of Mn, Ti and Zn (as shown Figure 3 ) is significantly larger.

[0101] See also Figure 5 and Figure 6 As shown, Figure 5 The microstructure diagram (TEM, 100000 times) of the aluminum alloy profile after the double-stage aging treatment of the present invention (Example 1) is shown in FIG. Figure 6 The microstructure of the aluminum alloy profile after the conventional aging process (Comparative Example 1) (TEM, 100000 times). Figure 5 and Figure 6 It can be seen that compared with the traditional aging process, the aluminum alloy profile after the double-stage aging treatment of the present invention has a significantly finer strengthening phase, a larger number of nuclei, and a larger strengthening phase number density (such as Figure 5 As shown), it can effectively improve the strength of aluminum alloy profiles.

[0102] Although the specific implementation modes of the present invention are described above, those skilled in the art should understand that the specific implementation modes described are only illustrative and are not intended to limit the scope of the present invention. Equivalent modifications and changes made by those skilled in the art in accordance with the spirit of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A high-strength 6-series aluminum alloy for photovoltaic aluminum materials, characterized in that: The 6 series aluminum alloy includes the following components in terms of mass percentage: Mg: 0.8-1.0%, Si: 0.5-0.7%, Cu: 0.2-0.3%, Cr: 0.1-0.25%, Mn: 0.3-0.5%, Ti: 0.02-0.04%, Zn: 0.1-0.25%, Fe≤0.5%, the balance is Al and unavoidable impurity elements.

2. The high-strength 6-series aluminum alloy for photovoltaic aluminum materials according to claim 1, characterized in that: The tensile strength of the 6 series aluminum alloy is ≥320 MPa, the yield strength is ≥290 MPa, and the thickness of the coarse grain layer is <0.3 mm.

3. The high-strength 6-series aluminum alloy for photovoltaic aluminum materials according to claim 1, characterized in that: Among the inevitable impurity elements, the total content of the impurities is less than 0.15%, and the content of each impurity element is less than 0.05%.

4. A method for preparing a high-strength 6-series aluminum alloy for photovoltaic aluminum materials according to any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: Ingredients: Provide raw materials according to the composition ratio of 6 series aluminum alloy; Melting and casting: Melting and casting the raw materials to form aluminum alloy ingots, and homogenizing the aluminum alloy ingots, including heating and cooling the aluminum alloy ingots in stages; Extrusion molding: Extrusion molding of aluminum alloy ingots to obtain aluminum alloy profiles; Aging treatment: Double-stage aging treatment is performed on aluminum alloy profiles.

5. The method for preparing a high-strength 6-series aluminum alloy for photovoltaic aluminum materials according to claim 4, characterized in that: The stepwise heating and cooling treatment of the aluminum alloy ingot specifically includes: The first stage: heating the aluminum alloy ingot to 300-320℃ and keeping it warm for 6 hours; The second stage: heating the aluminum alloy ingot to 560-580℃ and keeping it warm for 4h; The third stage: spray rapid cooling, cooling the aluminum alloy ingot to below 300°C at a cooling rate of 280°C / h or more; The fourth stage: slow cooling after being taken out of the furnace. The aluminum alloy ingot is placed outside the furnace to cool naturally to room temperature.

6. The method for preparing a high-strength 6-series aluminum alloy for photovoltaic aluminum materials according to claim 4, characterized in that: The double-stage aging treatment of the aluminum alloy profile specifically includes: The aluminum alloy profile is heated to 140-150°C and kept at this temperature for 4 hours, and then heated to 180-190°C and kept at this temperature for 4 hours. The aluminum alloy profile is then taken out of the furnace and naturally cooled to room temperature.

7. The method for preparing a high-strength 6-series aluminum alloy for photovoltaic aluminum materials according to claim 4, characterized in that: Before extruding the aluminum alloy ingot, the method also includes: heating the aluminum alloy ingot after homogenization to 480-510° C. and keeping the temperature for 2-5 hours.

8. The method for preparing a high-strength 6-series aluminum alloy for photovoltaic aluminum materials according to claim 7, characterized in that: The extrusion molding of the aluminum alloy ingot is specifically as follows: An extruder is used to extrude the heated aluminum alloy ingot, and ensure that the discharge temperature of the aluminum alloy profile reaches 510-540℃, wherein the extrusion barrel of the extruder needs to be preheated to 430-450℃, the extrusion die is preheated to 460-480℃ and kept warm for more than 3h, and the extruded aluminum alloy profile is treated with online strong air cooling or water cooling quenching.

9. The method for preparing a high-strength 6-series aluminum alloy for photovoltaic aluminum materials according to claim 4, characterized in that: In the process of melting and casting the raw materials to form aluminum alloy ingots, the component Ti is added online in the launder in the form of Al-Ti-B wire refiner in the final casting stage.

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