Preparation process of high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy

Abstract

The present invention discloses a preparation process for a high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy, belonging to the technical field of lead frame material production processes. The high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy described in the present invention contains, by mass percentage, 0.3-1.2% Mg, 0.5-1.4% Si, 5.0-7.8% Cu, 0.1-0.2% Ti, 0.01-0.1% B, and the remainder is Al and some unavoidable impurity elements. The method for preparing the finished material includes vacuum melting casting, pouring, forging, primary solid solution treatment, constant temperature vacuum treatment, reverse repeated asynchronous rolling treatment, secondary three-stage solid solution treatment, and incomplete artificial aging treatment. This process improves the strength and electrical conductivity of the aluminum-magnesium-silicon-copper alloy through reverse repeated asynchronous rolling treatment. Its workpieces can be used in the automotive, electronics, aerospace and other fields, and have very good industrial application prospects.

Description

Technical Field

[0001] The invention relates to a preparation process of a high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy, belonging to the technical field of lead frame material production processes. Background Art

[0002] High-strength, high-conductivity aluminum-magnesium-silicon-copper alloys have a high strength-to-weight ratio, excellent mechanical properties, formability, and corrosion resistance, making them widely used as lead frame materials in the automotive, electronics, aerospace, and other fields. However, the development of modern industry has placed higher demands on the strength and conductivity of aluminum-magnesium-silicon-copper alloys.

[0003] Currently, efforts to enhance the strength and conductivity of aluminum-magnesium-silicon-copper alloys by simply improving their elemental composition or adjusting their production processes have reached a bottleneck. However, by leveraging the synergistic effects of these two elements, the strength and conductivity of aluminum-magnesium-silicon-copper alloys can be further enhanced. This could significantly improve the performance of current domestic electronic devices and RF connectors.

[0004] Invention patent CN101100717A introduces a method for producing a high-strength aluminum-magnesium-silicon alloy with excellent forgeability. By adding iron additives, manganese additives, chromium additives, and titanium-boron refiners to the alloy, and then melting, furnace-deforming, purifying, casting into rods, homogenizing the rods, and forced water cooling, the aluminum-magnesium-silicon alloy has high strength and tensile strength, is not easy to deform or break, and can meet the requirements of automotive control arms.

[0005] Patent CN101597707A describes an aluminum-magnesium-silicon-copper alloy and its preparation method. By improving the elemental composition of the original 6061 alloy, it reduces deformation resistance and increases the alloy's plasticity. Patent CN109161743A describes a corrosion-resistant rare earth microalloyed aluminum alloy and its preparation method. By adding Ce and Y elements to promote heterogeneous grain growth, the alloy changes the size, morphology, and quantity of precipitated phases, improving corrosion resistance.

[0006] The aluminum alloy materials obtained by the above processes form different microstructures by adding different elements, improving the alloy's corrosion resistance and plasticity, but their strength and electrical properties are not considered. Therefore, it is necessary to provide a processing technology to improve the strength and conductivity of aluminum-magnesium-silicon-copper alloys to further expand the application of aluminum-magnesium-silicon-copper alloys in the automotive, electronics, aerospace and other fields. Summary of the Invention

[0007] To address the deficiencies in the prior art, the present invention provides a process for preparing a high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy. The specific preparation steps are as follows:

[0008] (1) Mg, Si, Ti, B alloy powders and Al and inevitable impurities are mixed in a ball mill and then smelted. During the smelting process, Cu powder is added to the alloy liquid through the powder feeding port and electromagnetic stirring is performed. Then, refining and impurity removal processes are carried out to obtain an alloy melt.

[0009] (2) The alloy melt obtained in step (1) is kept warm and then cast into a preheated mold to form an aluminum alloy plate.

[0010] (3) The aluminum alloy plate obtained in step (2) is placed in an air circulation resistance furnace for primary solution treatment and then annealing treatment.

[0011] (4) The annealed aluminum alloy is placed in a constant temperature vacuum box for constant temperature vacuum treatment.

[0012] (5) After the constant temperature vacuum treatment is completed, the aluminum alloy plate is subjected to reverse repeated asynchronous rolling treatment.

[0013] (6) After repeated asynchronous rolling treatment in the reverse direction, the aluminum alloy is subjected to a secondary three-stage solid solution treatment.

[0014] (7) After the secondary three-stage solution treatment, the aluminum alloy is subjected to incomplete artificial aging treatment to obtain a high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy.

[0015] Preferably, the total mass percentage of Mg, Si, Ti, B, Cu powder and Al and some inevitable impurity elements in step (1) is 100%, which contains 0.3-1.2% Mg, 0.5-1.4% Si, 5.0-7.8% Cu, 0.1-0.2% Ti, 0.01-0.1% B, and the balance is Al and some inevitable impurity elements.

[0016] Preferably, in step (1), the ball milling medium is a high-alumina ceramic ball, the ball milling speed is 180 r / min, the ball milling time is 2 h, the vacuum degree is below 50 Pa; the melting temperature is 640-670° C., and the melting time is 45 min.

[0017] Preferably, in step (2), the holding temperature is 750°C, the holding time is 30 minutes, and the mold is preheated to 200°C.

[0018] Preferably, the temperature of the initial solution treatment in step (3) is 490-530°C, the solution treatment time is 2h; the annealing temperature is 350-400°C, the annealing time is 2h, and the cooling rate is 5-10°C / s. The annealing treatment can improve the crystal structure, refine the crystals again, reduce the dislocation density and thus reduce the internal stress of the alloy, restore the machinability of the material, and provide favorable processing conditions for subsequent reverse repeated asynchronous rolling treatment.

[0019] Preferably, the temperature of the constant temperature vacuum in step (4) is 50° C., and the insulation time is 30 minutes.

[0020] Preferably, the reverse repeated asynchronous rolling treatment condition in step (5) is a total reduction of 75% to 80%; it is divided into 5 rolling passes, the reductions of the first two times are 25 to 30% and 20 to 25% respectively, and the remaining three times are reduced in a step-by-step manner, starting from 15% reduction, and the reduction is gradually reduced by 5% each time, that is, 15%, 10%, and 5%; while changing the reduction in the 5 rolling passes, the ratio of the upper and lower speeds of the working rolls is changed, which are 1.3, 0.7, 1.4, 0.6, and 1.0 respectively. The reverse repeated asynchronous rolling treatment makes the alloy grains fully refined, the grain boundary structure improved, and the inclusions in the alloy reduced, thereby obtaining an ideal organizational structure.

[0021] Preferably, the secondary three-stage solution treatment in step (6) is as follows: the first stage solution temperature is 410°C, and the solution time is 20 min; the second stage solution temperature is 440°C, and the solution time is 30 min; the third stage solution temperature is 465°C, and the solution time is 40 min.

[0022] Preferably, the incomplete artificial aging treatment temperature in step (7) is 150-170° C. and the time is 6 hours.

[0023] Principle of the present invention:

[0024] The strength and conductivity of aluminum-magnesium-silicon-copper alloys are closely related to the elemental content, rolling treatment, and the size, morphology, and number of precipitated phases. The addition of copper results in the formation of precipitates, such as the copper-rich magnesium-copper (Al2CuMg) phase, which increases the alloy's strength and conductivity. Silicon combines with magnesium to form Mg2Si precipitates, improving the alloy's strength and conductivity. The addition of titanium and boron forms intermediate phases that contribute to grain refinement. Annealing improves the crystal structure, refining the crystals, reducing dislocation density and, consequently, internal stress in the alloy, restoring the material's machinability and providing favorable processing conditions for subsequent reverse-repeated asynchronous rolling. Reverse-repeated asynchronous rolling, by varying the amount of downward pressure while altering the ratio of the upper and lower speeds of the working rolls, alters the alloy's grain structure during rolling, resulting in smaller grains. Smaller grains reduce electron scattering at grain boundaries, thereby improving the alloy's conductivity and strength. During the initial solution treatment, the alloy is heated to the solution temperature and held at that temperature for a period of time to allow the solute to fully dissolve into the matrix. During this process, the Mg2Si phase is dissolved into the solid solution. A secondary three-stage solution treatment plus incomplete artificial aging treatment ensures the desired Mg2Si precipitation phase, thereby improving the alloy's strength and conductivity. The synergistic effect of all these processes gives the aluminum-magnesium-silicon-copper alloy both high strength and high conductivity.

[0025] Beneficial effects of the present invention

[0026] (1) The present invention increases the copper content and combines vacuum melting casting, pouring, forging, initial solid solution treatment, constant temperature vacuum treatment, reverse repeated asynchronous rolling treatment, incomplete artificial aging treatment and other processes to obtain an ideal high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy.

[0027] (2) The increase of Cu can obtain the desired microstructure and improve the mechanical properties of the alloy. The increase of Ti and B helps to refine the grains.

[0028] (3) The specific reverse repeated asynchronous rolling pressure and roll speed ratio, annealing treatment, secondary three-stage solution temperature, solution time, and artificial aging treatment process ensure that the grain structure is improved, the grain refinement is high, and the formation of the required precipitation phase is promoted; among them, the secondary three-stage solution treatment + incomplete artificial aging treatment ensures the acquisition of the required Mg2Si precipitation phase, thereby improving the strength and conductivity of the alloy.

[0029] (4) The invention provides a new method for producing a high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the production process of the high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy material portion of the present invention. DETAILED DESCRIPTION

[0031] The present invention will be further described in detail below with reference to specific embodiments, but the protection scope of the present invention is not limited to the contents described above.

[0032] Example 1

[0033] Preparation of a high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy. The raw materials and contents used in this embodiment are shown in Table 1.

[0034] Table 1 Raw materials and contents used in Example 1

[0035] Mg Si Cu Ti B margin 0.3％ 0.5％ 5.0％ 0.1％ 0.01％ Al and the Inevitable Magazine

[0036] The specific preparation steps are as follows

[0037] (1) The alloy powders were mixed in a ball mill according to the Mg, Si, Ti, and B components in Table 1. The ball milling time was 2 h, the rotation speed was 180 r / min, and the vacuum degree reached below 50 Pa. The alloy powders were then smelted. During the smelting process, copper powder was added to the alloy liquid through the powder feeding port to interact with each other and perform electromagnetic stirring. The smelting temperature was 640 ° C and the smelting time was 45 min. Then, refining, impurity removal and other processes were carried out to obtain an alloy melt.

[0038] (2) The alloy melt obtained in step (1) was kept at 750°C for 30 minutes and then cast into a mold preheated to 200°C to form an aluminum alloy plate with a thickness of 30 mm.

[0039] (3) The aluminum alloy plate obtained in step (2) is placed in an air circulation resistance furnace for primary solution treatment at a temperature of 490°C for 2 hours to uniformly distribute the elements, and then annealing treatment is performed at a temperature of 350°C for 2 hours.

[0040] (4) The annealed aluminum alloy was placed in a constant temperature vacuum box for constant temperature vacuum treatment. After cooling to 50°C at a cooling rate of 5°C / s, the constant temperature vacuum was maintained for 30 minutes.

[0041] (5) After the constant temperature vacuum treatment is completed, the aluminum alloy plate is subjected to reverse repeated asynchronous rolling treatment, with a total reduction of 75%, divided into 5 rolling passes, the first two reductions being 25% and 20% respectively, and the remaining three reductions being reduced in a step-by-step manner, starting from 15% reduction and decreasing by 5% each time, i.e. 15%, 10%, and 5%; while changing the reduction in the 5 rolling passes, the ratio of the upper and lower speeds of the working rolls is changed, which are 1.3, 0.7, 1.4, 0.6, and 1.0 respectively.

[0042] (6) After the reverse repeated asynchronous rolling treatment, the aluminum alloy was subjected to a secondary three-stage solution treatment. The first stage solution temperature was 410℃, and the solution time was 20 min; the second stage solution temperature was 440℃, and the solution time was 30 min; the third stage solution temperature was 465℃, and the solution time was 40 min.

[0043] (7) After the secondary three-stage solution treatment, the aluminum alloy was subjected to incomplete artificial aging treatment at 150°C for 6 hours. The high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy was finally obtained.

[0044] The mechanical and electrical properties of the high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy obtained in this embodiment are shown in Table 2.

[0045] Table 2 Mechanical and electrical properties of aluminum-magnesium-silicon-copper alloy of Example 1

[0046] Yield strength / MPa Tensile strength / MPa Conductivity%IAC 285 372 62

[0047] Example 2

[0048] Preparation of a high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy. The raw materials and contents used in this example are shown in Table 3.

[0049] Table 3 Raw materials and contents used in Example 2

[0050] Mg Si Cu Ti B margin 1.1％ 1.1％ 7.8％ 0.15％ 0.08％ Al and the Inevitable Magazine

[0051] The specific preparation steps are as follows

[0052] (1) The alloy powders were mixed in a ball mill according to the Mg, Si, Ti, and B components in Table 3. The ball milling time was 2 h, the rotation speed was 180 r / min, and the vacuum degree was below 50 Pa. The alloy powders were then smelted. During the smelting process, copper powder was added to the alloy liquid through the powder feeding port to interact with each other and perform electromagnetic stirring. The smelting temperature was 660 ° C and the smelting time was 45 min. Then, refining, impurity removal and other processes were carried out to obtain an alloy melt.

[0053] (2) The alloy melt obtained in step (1) was kept at 750°C for 30 minutes and then cast into a mold preheated to 200°C to form an aluminum alloy plate with a thickness of 30 mm.

[0054] (3) The aluminum alloy plate obtained in step (2) is placed in an air circulation resistance furnace for primary solution treatment at a temperature of 520°C for 2 hours to uniformly distribute the elements, and then annealing treatment is performed at a temperature of 380°C for 2 hours.

[0055] (4) The annealed aluminum alloy was placed in a constant temperature vacuum box for constant temperature vacuum treatment. After cooling to 50°C at a cooling rate of 10°C / s, the constant temperature vacuum was maintained for 30 minutes.

[0056] (5) After the constant temperature vacuum treatment is completed, the aluminum alloy plate is subjected to reverse repeated asynchronous rolling treatment, with a total reduction of 80%, divided into 5 rolling passes, the first two reductions being 25% and 25% respectively, and the remaining three reductions being reduced in a step-by-step manner, starting from 15% reduction and decreasing by 5% each time, i.e. 15%, 10%, and 5%; while changing the reduction in the 5 rolling passes, the ratio of the upper and lower speeds of the working rolls is changed, which are 1.3, 0.7, 1.4, 0.6, and 1.0 respectively.

[0057] (6) After the reverse repeated asynchronous rolling treatment, the aluminum alloy was subjected to a three-stage solution treatment. The first stage solution temperature was 410°C and the solution time was 20 min; the second stage solution temperature was 440°C and the solution time was 30 min; the third stage solution temperature was 465°C and the solution time was 40 min.

[0058] (7) After the secondary three-stage solution treatment, the aluminum alloy was subjected to incomplete artificial aging treatment at 160°C for 6 hours. The high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy was finally obtained.

[0059] The mechanical and electrical properties of the high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy obtained in this embodiment are shown in Table 4.

[0060] Table 4 Mechanical and electrical properties of aluminum-magnesium-silicon-copper alloy in Example 2

[0061] Yield strength / MPa Tensile strength / MPa Conductivity%IAC 272 401 75

[0062] Example 3

[0063] Preparation of a high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy. The raw materials and contents used in this example are shown in Table 5.

[0064] Table 5 Raw materials and contents used in Example 3

[0065] Mg Si Cu Ti B margin 1.2％ 1.4％ 6.0％ 0.2％ 0.1％ Al and the Inevitable Magazine

[0066] The specific preparation steps are as follows

[0067] (1) The alloy powders were mixed in a ball mill according to the Mg, Si, Ti, and B components in Table 5. The ball milling time was 2 h, the rotation speed was 180 r / min, and the vacuum degree reached below 50 Pa. The alloy powders were then smelted. During the smelting process, copper powder was added to the alloy liquid through the powder feeding port to interact with each other and was electromagnetically stirred. The smelting temperature was 670 ° C and the smelting time was 45 min. Then, refining, impurity removal and other processes were carried out to obtain an alloy melt.

[0068] (2) The alloy melt obtained in step (1) was kept at 750°C for 30 minutes and then cast into a mold preheated to 200°C to form an aluminum alloy plate with a thickness of 30 mm.

[0069] (3) The aluminum alloy plate obtained in step (2) is placed in an air circulation resistance furnace for primary solution treatment at a temperature of 530°C for 2 hours to uniformly distribute the elements, and then annealing treatment is performed at a temperature of 390°C for 2 hours.

[0070] (4) The annealed aluminum alloy was placed in a constant temperature vacuum box for constant temperature vacuum treatment. After cooling to 50°C at a cooling rate of 8°C / s, the constant temperature vacuum was maintained for 30 minutes.

[0071] (5) After the constant temperature vacuum treatment is completed, the aluminum alloy plate is subjected to reverse repeated asynchronous rolling treatment, with a total reduction of 75%, divided into 5 rolling passes, the first two reductions being 25% and 20% respectively, and the remaining three reductions being reduced in a step-by-step manner, starting from 15% reduction and decreasing by 5% each time, i.e. 15%, 10%, and 5%; while changing the reduction in the 5 rolling passes, the ratio of the upper and lower speeds of the working rolls is changed, which are 1.3, 0.7, 1.4, 0.6, and 1.0 respectively.

[0072] (6) After the reverse repeated asynchronous rolling treatment, the aluminum alloy was subjected to a secondary three-stage solution treatment. The first stage solution temperature was 410℃, and the solution time was 20 min; the second stage solution temperature was 440℃, and the solution time was 30 min; the third stage solution temperature was 465℃, and the solution time was 40 min.

[0073] (7) After the secondary three-stage solution treatment, the aluminum alloy was subjected to incomplete artificial aging treatment at 170°C for 6 hours. The resulting high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy was obtained.

[0074] The mechanical and electrical properties of the high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy obtained in this embodiment are shown in Table 6.

[0075] Table 6 Mechanical and electrical properties of aluminum-magnesium-silicon-copper alloy of Example 3

[0076] Yield strength / MPa Tensile strength / MPa Conductivity%IAC 290 382 66

[0077] Example 4

[0078] Preparation of a high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy. The raw materials and contents used in this example are shown in Table 7.

[0079] Table 7 Raw materials and contents used in Example 4

[0080] Mg Si Cu Ti B margin 0.9% 1.4％ 7.0% 0.15％ 0.03％ Al and the Inevitable Magazine

[0081] The specific preparation steps are as follows:

[0082] (1) The alloy powders were mixed in a ball mill according to the Mg, Si, Ti, and B components in Table 7. The ball milling time was 2 h, the rotation speed was 180 r / min, and the vacuum degree reached below 50 Pa. The alloy powders were then smelted. During the smelting process, copper powder was added to the alloy liquid through the powder feeding port to interact with each other and was electromagnetically stirred. The smelting temperature was 650°C and the smelting time was 45 min. Then, refining and impurity removal processes were carried out to obtain an alloy melt.

[0083] (2) The alloy melt obtained in step (1) was kept at 750°C for 30 minutes and then cast into a mold preheated to 200°C to form an aluminum alloy plate with a thickness of 30 mm.

[0084] (3) The aluminum alloy plate obtained in step (2) is placed in an air circulation resistance furnace for primary solution treatment at a temperature of 530°C for 2 hours to uniformly distribute the elements, and then annealing treatment is performed at a temperature of 400°C for 2 hours.

[0085] (4) The annealed aluminum alloy was placed in a constant temperature vacuum box for constant temperature vacuum treatment. After cooling to 50°C at a cooling rate of 10°C / s, the constant temperature vacuum was maintained for 30 minutes.

[0086] (5) After the constant temperature vacuum treatment is completed, the aluminum alloy plate is subjected to reverse repeated asynchronous rolling treatment, with a total reduction of 80%, divided into 5 rolling passes. The reductions of the first two times are 30% and 20% respectively, and the remaining three times are reduced in a step-by-step manner, starting from 15% reduction and decreasing by 5% each time, i.e. 15%, 10%, and 5%; while changing the reduction in the 5 rolling passes, the ratio of the upper and lower speeds of the working rolls is changed, which are 1.3, 0.7, 1.4, 0.6, and 1.0 respectively.

[0087] (6) After the reverse repeated asynchronous rolling treatment, the aluminum alloy was subjected to a secondary three-stage solution treatment. The first stage solution temperature was 410℃, and the solution time was 20 min; the second stage solution temperature was 440℃, and the solution time was 30 min; the third stage solution temperature was 465℃, and the solution time was 40 min.

[0088] (7) After the secondary three-stage solution treatment, the aluminum alloy was subjected to incomplete artificial aging treatment at 165°C for 6 hours. The resulting high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy was obtained.

[0089] The mechanical and electrical properties of the high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy obtained in this embodiment are shown in Table 8.

[0090] Table 8 Mechanical and electrical properties of aluminum-magnesium-silicon-copper alloy in Example 4

[0091] Yield strength / MPa Tensile strength / MPa Conductivity%IAC 263 387 69

[0092] Comparative Example 1

[0093] The composition and preparation of the aluminum-magnesium-silicon-copper alloy in this embodiment are the same as those in Example 1, except that the forged alloy is directly subjected to reverse repeated asynchronous rolling. The specific preparation steps are as follows:

[0094] (1) The alloy powders were mixed in a ball mill according to the Mg, Si, Ti, and B components in Table 1. The ball milling time was 2 h, the rotation speed was 180 r / min, and the vacuum degree reached below 50 Pa. The alloy powders were then smelted. During the smelting process, copper powder was added to the alloy liquid through the powder feeding port to interact with each other and perform electromagnetic stirring. The smelting temperature was 640°C. Subsequently, refining and impurity removal processes were performed to obtain an alloy melt.

[0095] (2) The alloy melt obtained in step (1) was kept at 750°C for 30 minutes and then cast into a mold preheated to 200°C to form an aluminum alloy plate with a thickness of 30 mm.

[0096] (3) The aluminum alloy plate is subjected to reverse repeated asynchronous rolling treatment with a total reduction of 75%, which is divided into 5 rolling passes. The reductions of the first two passes are 25% and 20%, respectively. The remaining three passes are rolled in a step-by-step manner, starting from 15% reduction and decreasing by 5% each time, i.e. 15%, 10%, and 5%. While changing the reduction in the 5 rolling passes, the ratio of the upper and lower speeds of the working rolls is changed, which are 1.3, 0.7, 1.4, 0.6, and 1.0, respectively.

[0097] (4) After the reverse repeated asynchronous rolling treatment, the aluminum alloy was subjected to a secondary three-stage solution treatment. The first stage solution temperature was 410℃, and the solution time was 20 min; the second stage solution temperature was 440℃, and the solution time was 30 min; the third stage solution temperature was 465℃, and the solution time was 40 min.

[0098] (5) After the secondary three-stage solution treatment, the aluminum alloy was subjected to incomplete artificial aging treatment at 150°C for 6 hours. The aluminum-magnesium-silicon-copper alloy was finally obtained.

[0099] The mechanical and electrical properties of the finally obtained Al-Mg-Si-Cu alloy are shown in Table 9.

[0100] Table 9 Comparative Example 1 Mechanical and electrical properties of aluminum-magnesium-silicon-copper alloy

[0101] Yield strength / MPa Tensile strength / MPa Conductivity%IAC 280 360 60

[0102] By comparison with Example 1, it can be seen that the initial solid solution and annealing treatment after forging can significantly improve the mechanical and electrical properties of the material. This is because compared with the comparative example in which the initial solid solution and annealing treatment are not performed after forging, the solid solution and annealing treatment in Example 1 can increase the required precipitation phase formation while reducing the internal stress of the alloy and restore the machinability, thereby providing favorable processing conditions for subsequent reverse repeated asynchronous rolling treatment, thereby increasing the mechanical and electrical properties of the alloy.

[0103] Comparative Example 2

[0104] The composition and preparation of the aluminum-magnesium-silicon-copper alloy in this embodiment are the same as those in Example 2, except that the alloy after constant temperature vacuum treatment is directly subjected to a secondary three-stage solid solution treatment. The specific preparation steps are as follows:

[0105] (1) The alloy powders were mixed in a ball mill according to the Mg, Si, Ti, and B components in Table 3. The ball milling time was 2 h, the rotation speed was 180 r / min, and the vacuum degree was below 50 Pa. The alloy powders were then smelted. During the smelting process, copper powder was added to the alloy liquid through the powder feeding port to interact with each other and perform electromagnetic stirring. The smelting temperature was 660 ° C and the smelting time was 45 min. Then, refining, impurity removal and other processes were carried out to obtain an alloy melt.

[0106] (2) The alloy melt obtained in step (1) was kept at 750°C for 30 minutes and then cast into a mold preheated to 200°C to form an aluminum alloy plate with a thickness of 30 mm.

[0107] (3) The aluminum alloy plate obtained in step (2) is placed in an air circulation resistance furnace for primary solution treatment at a temperature of 520°C for 2 hours to uniformly distribute the elements, and then annealing treatment is performed at a temperature of 380°C for 2 hours.

[0108] (4) The annealed aluminum alloy was placed in a constant temperature vacuum box for constant temperature vacuum treatment, cooled to 50°C at a cooling rate of 10°C / s, and kept at constant temperature vacuum for 30 minutes.

[0109] (5) After constant temperature vacuum treatment, the aluminum alloy was subjected to a secondary three-stage solution treatment. The first stage solution temperature was 410℃, and the solution time was 20 min; the second stage solution temperature was 440℃, and the solution time was 30 min; the third stage solution temperature was 465℃, and the solution time was 40 min.

[0110] (6) After the secondary three-stage solution treatment, the aluminum alloy was subjected to incomplete artificial aging treatment at 160°C for 6 hours. The high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy was finally obtained.

[0111] The mechanical and electrical properties of the finally obtained Al-Mg-Si-Cu alloy are shown in Table 10.

[0112] Table 10 Comparative Example 2 Mechanical and electrical properties of aluminum-magnesium-silicon-copper alloy

[0113] Yield strength / MPa Tensile strength / MPa Conductivity%IAC 252 370 62

[0114] By comparison with Example 2, it can be seen that the reverse repeated asynchronous rolling treatment after the constant temperature vacuum treatment can significantly improve the mechanical and electrical properties of the material. This is because compared with the comparative example in which the reverse repeated asynchronous rolling treatment is not performed after the constant temperature vacuum treatment, the reverse repeated asynchronous rolling treatment in Example 2 changes the ratio of the upper and lower rotation speeds of the working rolls while changing the downward pressure, which can change the grain structure of the alloy during the rolling process, making the grain size smaller. The smaller the grains, the less electron scattering at the grain boundaries, thereby increasing the mechanical and electrical properties of the alloy.

[0115] Comparative Example 3

[0116] The composition and preparation of the aluminum-magnesium-silicon-copper alloy in this embodiment are the same as those in Example 3, except that an incomplete artificial aging treatment is performed at the end. The specific preparation steps are as follows:

[0117] (1) The alloy powders were mixed in a ball mill according to the Mg, Si, Ti, and B components in Table 5. The ball milling time was 2 h, the rotation speed was 180 r / min, and the vacuum degree reached below 50 Pa. The alloy powders were then smelted. During the smelting process, copper powder was added to the alloy liquid through the powder feeding port to interact with each other and was electromagnetically stirred. The smelting temperature was 670 ° C and the smelting time was 45 min. Then, refining, impurity removal and other processes were carried out to obtain an alloy melt.

[0118] (2) The alloy melt obtained in step (1) was kept at 750° C. for 30 minutes and then cast into a preheated mold to form an aluminum alloy plate with a thickness of 30 mm.

[0119] (3) The aluminum alloy plate obtained in step (2) is placed in an air circulation resistance furnace for primary solution treatment at a temperature of 530°C for 2 hours to uniformly distribute the elements, and then annealing treatment is performed at a temperature of 390°C for 2 hours.

[0120] (4) The annealed aluminum alloy was placed in a constant temperature vacuum box for constant temperature vacuum treatment, cooled to 50°C at a cooling rate of 8°C / s, and kept at constant temperature vacuum for 30 minutes.

[0121] (5) After the constant temperature vacuum treatment is completed, the aluminum alloy plate is subjected to reverse repeated asynchronous rolling treatment, with a total reduction of 75%, divided into 5 rolling passes, the first two reductions being 25% and 20% respectively, and the remaining three reductions being reduced in a step-by-step manner, starting from 15% reduction and decreasing by 5% each time, i.e. 15%, 10%, and 5%; while changing the reduction in the 5 rolling passes, the ratio of the upper and lower speeds of the working rolls is changed, which are 1.3, 0.7, 1.4, 0.6, and 1.0 respectively.

[0122] (6) After the reverse repeated asynchronous rolling treatment, the aluminum alloy was subjected to a secondary three-stage solution treatment. The first stage solution temperature was 410 ° C and the solution time was 20 min; the second stage solution temperature was 440 ° C and the solution time was 30 min; the third stage solution temperature was 465 ° C and the solution time was 40 min. The aluminum-magnesium-silicon-copper alloy finally obtained was

[0123] The mechanical and electrical properties of the finally obtained Al-Mg-Si-Cu alloy are shown in Table 11.

[0124] Table 11 Mechanical and electrical properties of aluminum-magnesium-silicon-copper alloy of comparative example 3

[0125] Yield strength / MPa Tensile strength / MPa Conductivity%IAC 278 369 52

[0126] By comparison with Example 3, it can be seen that the secondary three-stage solid solution + incomplete artificial aging treatment can significantly improve the mechanical and electrical properties of the material. This is because compared with the comparative example without secondary multi-stage solid solution + incomplete artificial aging, the secondary three-stage solid solution + incomplete artificial aging treatment is performed in Example 2. During the solid solution treatment, the Mg2Si phase in the alloy is dissolved into the solid solution, and the subsequent incomplete artificial aging treatment promotes the precipitation of the Mg2Si phase; thereby improving the mechanical and electrical properties of the alloy.

[0127] Comparative Example 4

[0128] The preparation and heat treatment process of the aluminum-magnesium-silicon-copper alloy in this embodiment are the same as those in Example 4, except that the composition is as shown in Table 12:

[0129] Table 12 Chemical composition of aluminum-magnesium-silicon-copper alloy of comparative example 4

[0130] Mg Si Cu Ti B margin 0.9％ 1.4％ 4.0％ 0.05％ 0.01％ Al and the Inevitable Magazine

[0131] The mechanical and electrical properties of the finally obtained Al-Mg-Si-Cu alloy are shown in Table 13.

[0132] Table 13 Mechanical and electrical properties of aluminum-magnesium-silicon-copper alloy of comparative example 4

[0133] Yield strength / MPa Tensile strength / MPa Conductivity%IAC 255 353 56

[0134] By comparison with Example 4, it can be seen that the mechanical and electrical properties of the aluminum alloy samples with reduced Cu, Ti and B element contents are lower than those of the alloy of Example 4 with a specific content. This is because the increase in copper element will cause a copper-rich magnesium-copper (Al2CuMg) phase to appear in the alloy, which increases the strength and conductivity of the alloy; the increase in Ti and B forms an intermediate phase, which helps to refine the grains, thereby improving the mechanical and electrical properties of the aluminum-magnesium-silicon-copper alloy.

[0135] In summary, the initial solid solution + annealing treatment, reverse repeated asynchronous rolling treatment, secondary multi-stage solid solution + secondary three-stage solid solution treatment, and regulation of Cu, Ti, and B content described in the present invention can effectively improve the dissolution of the Mg2Si phase in the solid solution stage of the aluminum-magnesium-silicon-copper alloy, as well as the subsequent precipitation, and the intermediate phase formed by the increase of Ti and B, which helps to refine the grains. The reverse repeated asynchronous rolling treatment changes the ratio of the upper and lower speeds of the working rolls while changing the downward pressure, which can change the grain structure of the alloy during the rolling process, making the grain size smaller. The finer the grain, the less electron scattering at the grain boundary. The mechanical and electrical properties of the aluminum-magnesium-silicon-copper alloy are improved under the synergistic effect of grain refinement strengthening, dislocation strengthening, and second phase strengthening. It is suitable for industrial applications and provides a feasible technical solution for the preparation of aluminum-magnesium-silicon-copper alloy materials for automobiles, electronics, and aerospace.

[0136] Finally, it should be noted that the present invention is not limited to the details of the exemplary embodiments described above and that the invention may be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0137] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A process for preparing a high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy, characterized by: The specific preparation steps are as follows: (1) Mg, Si, Ti, B alloy powders and Al and inevitable impurities are mixed in a ball mill and then smelted. During the smelting process, Cu powder is added to the alloy liquid through the powder feeding port and electromagnetic stirring is performed. Then, refining and impurity removal processes are carried out to obtain an alloy melt. (2) keeping the alloy melt obtained in step (1) warm and then casting it into a preheated mold to form an aluminum alloy plate; (3) placing the aluminum alloy plate obtained in step (2) in an air circulation resistance furnace for primary solution treatment and then performing annealing treatment; (4) placing the annealed aluminum alloy into a constant temperature vacuum box for constant temperature vacuum treatment; (5) After the constant temperature vacuum treatment is completed, the aluminum alloy plate is subjected to reverse repeated asynchronous rolling treatment; (6) After repeated asynchronous rolling in the reverse direction, the aluminum alloy is subjected to a secondary three-stage solid solution treatment; (7) After the secondary three-stage solution treatment, the aluminum alloy is subjected to incomplete artificial aging treatment to obtain a high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy; The total mass percentage of Mg, Si, Ti, B, Cu powder, Al and some inevitable impurity elements in step (1) is 100%, which contains 0.3~1.2% Mg, 0.5~1.4% Si, 5.0~7.8% Cu, 0.1~0.2% Ti, 0.01~0.1% B, and the balance is Al and some inevitable impurity elements.

2. The process for preparing the high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy according to claim 1, characterized in that: In step (1), the ball milling medium is high-alumina ceramic balls, the ball milling speed is 180 r / min, the ball milling time is 2 h, the vacuum degree is below 50 Pa; the melting temperature is 640~670°C, and the melting time is 45 min.

3. The process for preparing the high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy according to claim 1, characterized in that: In step (2), the holding temperature is 750°C, the holding time is 30 minutes, and the mold is preheated to 200°C.

4. The process for preparing the high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy according to claim 1, characterized in that: In step (3), the temperature of the initial solution treatment is 490-530°C, and the solution treatment time is 2 h; the annealing temperature is 350-400°C, and the annealing time is the holding time 2 h.

5. The process for preparing the high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy according to claim 1, characterized in that: In step (4), the temperature of the constant temperature vacuum is 50°C, the holding time is 30 minutes, and the cooling rate is 5-10°C / s.

6. The process for preparing the high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy according to claim 1, characterized in that: The reverse repeated asynchronous rolling treatment condition in step (5) is a total reduction of 75% to 80%; it is divided into 5 rolling passes, the first two reductions are 25 to 30% and 20 to 25% respectively, and the remaining three are reduced in a step-by-step manner, starting from 15% reduction and decreasing by 5% each time, i.e. 15%, 10%, and 5%; while changing the reduction in the 5 rolling passes, the ratio of the upper and lower speeds of the working rolls is changed, which are 1.3, 0.7, 1.4, 0.6, and 1.0 respectively.

7. The process for preparing the high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy according to claim 1, characterized in that: The secondary three-stage solution treatment in step (6) is as follows: the first stage solution temperature is 410°C, and the solution time is 20 min; the second stage solution temperature is 440°C, and the solution time is 30 min; the third stage solution temperature is 465°C, and the solution time is 40 min.

8. The process for preparing the high-strength and high-conductivity aluminum-magnesium-silicon-copper alloy according to claim 1, characterized in that: The incomplete artificial aging treatment temperature in step (7) is 150-170°C and the time is 6 hours.

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