Method for producing 7075 aluminum alloy by electrolyzing primary aluminum liquid

Abstract

The invention provides a method for producing 7075 aluminum alloy by electrolyzing primary aluminum liquid, and belongs to the technical field of aluminum alloy preparation. According to the method, the 7075 aluminum alloy is directly produced in a short process by taking the electrolytic primary aluminum liquid as the raw material, so that the production process is shortened, the energy consumption and the production cost are reduced, and the production efficiency is improved. According to the method, through accurate component adjustment and refining treatment, the quality and performance of the aluminum alloy are guaranteed, the stability of the product quality is guaranteed, and specific casting and homogenizing treatment processes are adopted, so that the structure uniformity and mechanical performance of the aluminum alloy are improved.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum alloy preparation, and in particular to a method for producing 7075 aluminum alloy by electrolyzing raw aluminum liquid. Background Art

[0002] 7075 aluminum alloy is a high-strength, heat-treatable alloy with good mechanical properties, corrosion resistance and processing performance. It is widely used in aerospace, automobile manufacturing and machinery manufacturing. The traditional production method of 7075 aluminum alloy is usually to first melt aluminum products from various sources, and then add various alloy elements for refining, casting and other processes, that is, to use remelted aluminum production.

[0003] The method of preparing alloy by remelting aluminum is to select appropriate aluminum ingots and alloy additives for remelting according to the target alloy. If waste aluminum products are selected, they need to be pre-processed by screening and impurity removal, and the burn-out rate of the required alloy components is estimated. After melting in the furnace, the required components are added to the furnace in sequence and at a speed according to the specific process conditions, and then cast into shape after refining and filtering, and then sawed and stored according to the size requirements. The composition of the alloy liquid is tested during the smelting process, and the alloy composition is adjusted according to the results to ensure that it meets the requirements.

[0004] The process of remelting aluminum to prepare alloys is as follows: raw material preparation → pretreatment → batching → remelting → alloying → refining → casting → sawing → warehousing.

[0005] During the remelting process of aluminum ingots, the aluminum liquid will react with oxygen in the air, causing some aluminum to be oxidized, causing burnout and reducing the output of aluminum ingots. In addition, because the oxidation products may be mixed in the aluminum liquid, the quality of the aluminum ingots is affected. The remelting method also has a long production process, high energy consumption and high production costs. Therefore, it is necessary to provide a 7075 aluminum alloy production method that can reduce energy consumption and reduce burnout. Summary of the invention

[0006] In view of this, the present invention provides a method for producing 7075 aluminum alloy by electrolyzing raw aluminum liquid. The method uses raw aluminum liquid to prepare 7075 aluminum alloy, which can optimize the source process. The ingredients and alloying can be added directly to the raw materials, reducing the burning loss during the remelting process, thereby reducing costs and improving production efficiency. The method has a short process and can save energy.

[0007] The method for producing 7075 aluminum alloy by electrolyzing raw aluminum liquid of the present invention comprises the following steps:

[0008] (1) Raw material preparation: according to the element content of 7075 aluminum alloy, prepare electrolytic aluminum liquid and alloy material; then prepare the cut head within the composition range of 7075 aluminum alloy as cold material, and aluminum-beryllium master alloy and titanium block as auxiliary materials; the mass proportion of beryllium in the aluminum-beryllium master alloy is 3%;

[0009] (2) After the melting furnace is heated up, the materials are added, and rough mixing, soaking and electromagnetic stirring are carried out in sequence. During the stirring process, aluminum liquid is continuously added according to the alloy composition; then 25-35% of cold material is added by mass, and the composition calculation is paid attention to during the addition process;

[0010] (3) Raise the temperature to 738°C to 765°C for precise feeding, soak for 20 to 25 minutes after feeding, then stir by electromagnetic for 25 to 30 minutes before sampling and analysis. If the ingredients are unqualified, continue to feed and refine;

[0011] (4) After the analysis is qualified, the mixed gas is used for refining at a refining temperature of 745-765°C; after the refining is completed, the furnace is deslagging, and the mixture is left to stand for 20-30 minutes, and the temperature is controlled at 738-745°C for material transfer preparation; the mixed gas is a mixture of chlorine and argon; the volume proportion of chlorine in the mixed gas is 2%, and the volume proportion of argon is 98%;

[0012] (5) Cleaning the furnace, removing slag and adding auxiliary materials: Clean the holding furnace, remove slag, and then transfer the materials. Before the transfer is completed, add titanium blocks and 3% aluminum-beryllium master alloy, then adjust the elements to the batching value, and then add cold materials;

[0013] (6) After the material transfer is completed, the temperature is controlled at 735-745°C, and after stirring for 5 minutes, a sample is taken for analysis, and the surface scum is scraped off to adjust the composition; the holding furnace refining is continued at 735-745°C, and the scum is scraped off after the refining is completed, and the aluminum liquid is allowed to stand for 30-35 minutes, and then degassing and filtering are performed to obtain aluminum liquid;

[0014] (7) First, 50 to 80 mm of electrolytic aluminum liquid at 740 to 750 ° C is added to form a bottom layer, and then the temperature is controlled to be 720 to 735 ° C for casting, 2.5 kg / t aluminum titanium boron wire is added online as a crystal nucleus for grain refinement, and the ingot is cooled to obtain an edge solidified ingot, and then tempering is performed when the pouring gate solidifies 1 / 3 to 1 / 2;

[0015] (8) After tempering, the alloy was kept at 468°C for 40 hours and the metal temperature was kept within ±5°C for homogenization annealing to obtain 7075 aluminum alloy.

[0016] Preferably, the element contents of the 7075 aluminum alloy are as follows: Si content is 0.13-0.14%, Fe content is 0.33-0.35%, Cu content is 1.53-1.54%, Mn content is ≤0.10%, Mg content is 2.4-2.55%, Cr content is 0.22-0.24%, Zn content is 5.7-5.8%, Ti content is 0.03-0.04%, the individual content of other impurities is ≤0.03%, the total content is ≤0.12%, and the balance is Al and unavoidable impurities.

[0017] Preferably, the aluminum content in the electrolytic aluminum liquid in step (1) is ≥99.85%.

[0018] Preferably, the feeding temperature in step (2) is 745-755°C.

[0019] Preferably, the soaking time in step (2) is 20 to 25 minutes; and the electromagnetic stirring time is 10 to 15 minutes.

[0020] Preferably, the amount of the titanium block added in step (5) is 2-2.2 kg / t.Al; the amount of the 3% aluminum-beryllium master alloy added is 0.25-0.3 kg / t; and the mass ratio of the cold material added is ≥30%.

[0021] Preferably, the specific steps of refining in step (6) are: first artificially refining in a chlorine-argon mixed gas for 20 to 25 minutes, and then opening the air permeable brick and using argon to refine for 20 to 25 minutes; the volume proportion of chlorine in the mixed gas is 2%, and the volume proportion of argon is 98%.

[0022] Preferably, the filtration in step (6) is firstly carried out by plate type coarse filtration using a 584*584mm, 40ppm ceramic filter, and then the melt is purified by secondary filtration using a deep bed filtration with a flow filtration accuracy of 10-20μm; the empty filter box insulation temperature of the two filtrations is 730-750°C, the filter box furnace temperature is set to 850°C, the filter box with material insulation temperature is 720-740°C, and the filter box furnace temperature is set to 800°C;

[0023] Preferably, the casting speed in the casting process of step (7) is 40-45 mm / min; the flow rate of the casting cooling water is 800-1500 L / min;

[0024] The tempering temperature is 650-750° C. and the tempering time is 30-60 min.

[0025] Preferably, the specific method of the homogenization annealing in step (8) is:

[0026] First, heat to 180°C at a rate of 100°C / h, keep warm for 1 hour, then continue to heat by 100°C at a rate of 100°C / h, and keep warm for 1 hour. After multiple heating and keeping warm, heat to 460-480°C, and then keep warm for 40 hours.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention provides a method for producing 7075 aluminum alloy by electrolyzing original aluminum liquid, which directly produces 7075 aluminum alloy by short process using original aluminum liquid as raw material, shortens the production process, reduces energy consumption and production cost, and improves production efficiency. The present invention ensures the quality and performance of aluminum alloy and the stability of product quality through precise composition adjustment and refining treatment, and adopts specific casting and homogenization treatment processes to improve the organizational uniformity and mechanical properties of aluminum alloy. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with the embodiments.

[0030] Example 1

[0031] A method for producing 7075 aluminum alloy by electrolyzing raw aluminum liquid, the steps are as follows:

[0032] (1) Raw material preparation: According to the element content of 7075 aluminum alloy, prepare electrolytic aluminum liquid with aluminum content ≥ 99.85% as the basic raw material, and prepare other alloy materials to adjust the chemical composition to meet the requirements;

[0033] The specific element contents of 7075 aluminum alloy are as follows: Si content 0.13-0.14%, Fe content 0.33-0.35%, Cu content 1.53-1.54%, Mn content ≤0.10%, Mg content 2.4-2.55%, Cr content 0.22-0.24%, Zn content 5.7-5.8%, Ti content 0.03-0.04%, other impurities single content ≤0.03%, total content ≤0.12%, the balance is Al and unavoidable impurities;

[0034] Prepare the cut ends within the composition range of 7075 aluminum alloy as cold material, and 3% aluminum beryllium master alloy and titanium block as auxiliary materials;

[0035] (2) The furnace is heated up, cleaned and slag removed. The temperature is controlled at 750°C before the materials are added. After rough mixing, they are soaked for 20 minutes and electromagnetically stirred for 10 minutes. During the stirring process, the remaining aluminum liquid is added according to the alloy composition. Then, 30% by mass of cold material is added. Pay attention to the composition calculation during the addition process.

[0036] (3) Raise the temperature to 738 °C for precise feeding, soak for 20 min after feeding, and then stir with electromagnetic stirring for 30 min;

[0037] (4) After stirring for 10 minutes, the mixture of chlorine and argon (2% chlorine and 98% argon) is used for refining at a refining temperature of 750°C. After the refining is completed, the furnace is deslagging and allowed to stand for 20 minutes. The temperature is controlled at 738-745°C for material transfer preparation. Sampling is required before refining. Three samples are taken for analysis according to the left, middle and right sampling standards. If the components are unqualified, the material can be supplemented again, and then the stirring process is continued for reprocessing.

[0038] (5) Cleaning the furnace, removing slag and adding auxiliary materials: Clean the holding furnace, remove slag, and then transfer the materials. Before the end of the transfer, add 2 kg / t.Al of titanium block and 0.25 kg / t.Al of 3% aluminum beryllium master alloy, and then adjust the elements to the batching value, and add 30% of cold material;

[0039] (6) After the material transfer is completed, the temperature is controlled at 740°C, and after stirring for 5 minutes, a sample is taken for analysis, and the surface scum is scraped off to adjust the composition; the holding furnace refining is continued at 740°C, and after the refining is completed, the scum is scraped off, and the mixture is allowed to stand for 35 minutes, and then degassing is performed until the hydrogen content is [H] = 0.12 ml / g.Al, and finally the aluminum liquid is obtained by filtration;

[0040] The specific steps of the refining are: firstly, manually refining in a chlorine-argon mixed gas (2% chlorine and 98% argon) for 20 minutes, and then refining in a permeable brick for 20 minutes;

[0041] The filtration is firstly carried out by plate type coarse filtration using a 584*584mm, 40ppm ceramic filter, and then the melt is purified by secondary filtration in a deep bed filtration with a flow filtration accuracy of 10μm; the empty box insulation temperature of the filtration box is 740℃, and the furnace temperature of the filter box is set to 850℃; the filter box with material insulation temperature is 730℃, and the furnace temperature of the filter box is set to 800℃;

[0042] (7) First, add 60 mm of pure aluminum at 750 ° C to lay the bottom, then control the temperature to 730 ° C (when casting starts at the aluminum outlet of the insulation furnace) for casting, add 2.5 kg / t aluminum titanium boron wire online as a crystal nucleus to refine the grains, cool to obtain an ingot with solidified edges, and then temper (tempering temperature is 668 ° C, time is 30 min) when the pouring gate solidifies 1 / 3; the relationship between casting speed, cooling water parameters, casting temperature parameters and ingot length is shown in Table 1:

[0043] Table 1

[0044]

[0045]

[0046] After tempering, homogenization annealing is performed to obtain 7075 aluminum alloy; the specific parameters of the homogenization annealing are:

[0047] First, heat to 180°C at a rate of 100°C / h, keep warm for 1 hour, then continue to heat to 100°C at a rate of 100°C / h, and keep warm for 1 hour. Repeat the same heating and keeping method for multiple times (each time by 100°C) until the temperature reaches 468±5°C, and then keep warm for 40 hours.

[0048] The mass fractions (%) of the elements in the 7075 aluminum alloy prepared in Example 1 are shown in Table 1:

[0049] Table 1

[0050]

[0051] The properties of the 7075 aluminum alloy prepared in Example 1 are shown in Table 2:

[0052] Table 2

[0053]

[0054] Comparative Example 1

[0055] A method for producing 7075 aluminum alloy by electrolyzing raw aluminum liquid, the steps are as follows:

[0056] (1) Raw material preparation: According to the element content of 7075 aluminum alloy, prepare electrolytic aluminum liquid with aluminum content ≥ 99.85% as the basic raw material, and prepare other alloy materials to adjust the chemical composition to meet the requirements;

[0057] The specific element contents of 7075 aluminum alloy are as follows: Si content ≤ 0.10%, Fe content 0.28%, Cu content 1.54%, Mn content ≤ 0.10%, Mg content 2.65%, Cr content 0.22%, Zn content 5.781%, Ti content 0.025%, other impurities single content ≤ 0.03%, total content ≤ 0.12%, the balance is Al;

[0058] Prepare the cut ends within the composition range of 7075 aluminum alloy as cold material, and 3% aluminum beryllium master alloy and titanium block as auxiliary materials;

[0059] The other steps are the same as in Example 1.

[0060] The mass fraction (%) of the elements of the 7075 aluminum alloy prepared in Comparative Example 1 is shown in Table 3:

[0061] Table 3

[0062]

[0063] The properties of the 7075 aluminum alloy prepared in Comparative Example 1 are shown in Table 4:

[0064] Table 4

[0065]

[0066] Comparative Example 2

[0067] According to the steps of Example 1, a method for electrolyzing raw aluminum liquid to produce 7075 aluminum alloy is provided. The refining steps of Comparative Example 2 are as follows:

[0068] (6) After the material transfer is completed, the temperature is controlled at 740°C, and after stirring for 5 minutes, a sample is taken for analysis, and the surface scum is scraped off to adjust the composition; the holding furnace refining is continued at 740°C, and after the refining is completed, the scum is scraped off, and the mixture is allowed to stand for 35 minutes, and then degassing is performed until the hydrogen content is [H] = 0.12 ml / g.Al, and finally the aluminum liquid is obtained by filtration;

[0069] The specific steps of the refining are: firstly, manually refining in argon (99.9993% argon) for 20 minutes, and then refining in the air-permeable brick for 20 minutes;

[0070] The filtration is firstly carried out by plate type coarse filtration using a 584*584mm, 40ppm ceramic filter, and then the melt is purified by secondary filtration in a deep bed filtration with a flow filtration accuracy of 10μm; the empty box insulation temperature of the filtration box is 740℃, and the furnace temperature of the filter box is set to 850℃; the filter box with material insulation temperature is 730℃, and the furnace temperature of the filter box is set to 800℃;

[0071] The other steps are the same as in Example 1.

[0072] The mass fraction (%) of the elements of the 7075 aluminum alloy prepared in Comparative Example 2 is shown in Table 5:

[0073] Table 5

[0074]

[0075] The properties of the 7075 aluminum alloy prepared in Comparative Example 2 are shown in Table 6:

[0076] Table 6

[0077]

[0078]

[0079] Comparative Example 3

[0080] A production method of 7075 aluminum alloy,

[0081] The difference between Comparative Example 3 and Example 1 is that in Comparative Example 3, the electrolytic aluminum liquid with an aluminum content ≥ 99.85% in Example 1 is replaced with an aluminum ingot with an aluminum content ≥ 99.70%.

[0082] The steps are as follows: (1) Raw material preparation: according to the element content of 7075 aluminum alloy, prepare aluminum ingots with an aluminum content ≥ 99.70% and other solid materials whose composition meets the 7075 standard composition as basic raw materials, and prepare other alloy materials for adjusting the chemical composition to meet the requirements;

[0083] The specific element contents of 7075 aluminum alloy are as follows: Si content 0.13-0.14%, Fe content 0.33-0.35%, Cu content 1.53-1.54%, Mn content ≤0.10%, Mg content 2.4-2.55%, Cr content 0.22-0.24%, Zn content 5.7-5.8%, Ti content 0.03-0.04%, other impurities single content ≤0.03%, total content ≤0.12%, the balance is Al and unavoidable impurities;

[0084] Prepare the cut ends within the composition range of 7075 aluminum alloy as cold material, and aluminum-titanium master alloy as auxiliary material;

[0085] (2) The furnace is heated and cleaned, slag is removed, and the solid material is added and then the temperature is continuously raised until the solid material is melted; after the solid material is melted and the temperature reaches 750°C, it is roughly mixed and soaked for 20 minutes, and electromagnetically stirred for 10 minutes;

[0086] (3) Raise the temperature to 740°C for precise feeding, soak for 20 min after feeding, and then stir for 30 min;

[0087] The remaining steps are the same as in Example 1.

[0088] The mass fractions (%) of the elements in the 7075 aluminum alloy prepared in Comparative Example 3 are shown in Table 7:

[0089] Table 7

[0090]

[0091] The properties of the 7075 aluminum alloy prepared in Comparative Example 3 are shown in Table 8:

[0092] Table 8

[0093]

[0094] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for producing 7075 aluminum alloy by electrolyzing raw aluminum liquid, characterized in that: The following steps are involved: (1) Raw material preparation: Prepare electrolytic aluminum liquid and alloy materials according to the element content of 7075 aluminum alloy; Then, a cut head in the range of 7075 aluminum alloy composition is prepared as a cold material, and an aluminum-beryllium master alloy and a titanium block are prepared as auxiliary materials; the mass proportion of beryllium in the aluminum-beryllium master alloy is 3%; (2) After the melting furnace is heated up, the materials are added, and rough mixing, soaking and electromagnetic stirring are carried out in sequence. During the stirring process, aluminum liquid is continuously added according to the alloy composition; then 25-35% of cold material is added by mass, and the composition calculation is paid attention to during the addition process; (3) Raise the temperature to 738°C to 765°C for precise feeding, soak for 20 to 25 minutes after feeding, and then stir with electromagnetic stirring for 25 to 30 minutes; (4) using a mixed gas for refining at a refining temperature of 745-765° C.; after the refining is completed, the furnace is deslagging, left to stand for 20-30 minutes, and the temperature is controlled at 738-745° C. for material transfer preparation; the mixed gas is a mixed gas of chlorine and argon; the volume proportion of chlorine in the mixed gas is 2%, and the volume proportion of argon is 98%; (5) Cleaning the furnace, removing slag and adding auxiliary materials: Clean the holding furnace, remove slag, and then transfer the materials. Before the transfer is completed, add titanium blocks and 3% aluminum-beryllium master alloy, then adjust the elements to the batching value, and then add cold materials; (6) After the material transfer is completed, the temperature is controlled at 735-745°C, and after stirring for 5 minutes, a sample is taken for analysis, and the surface scum is scraped off to adjust the composition; the holding furnace refining is continued at 735-745°C, and the scum is scraped off after the refining is completed, and the aluminum liquid is allowed to stand for 30-35 minutes, and then degassing and filtering are performed to obtain aluminum liquid; (7) First, add 50 to 80 mm of electrolytic aluminum liquid at 740 to 750 ° C to lay the bottom, then control the temperature to 720 to 735 ° C for casting, add 2.5 kg / t aluminum titanium boron wire online, cool to obtain an ingot with solidified edges, and then perform tempering when the pouring gate solidifies 1 / 3 to 1 / 2; (8) After tempering, the alloy was kept at 468°C for 40 hours and the metal temperature was kept within ±5°C for homogenization annealing to obtain 7075 aluminum alloy.

2. The method for producing 7075 aluminum alloy by electrolyzing raw aluminum liquid according to claim 1, characterized in that: The element contents of the 7075 aluminum alloy are as follows: Si content is 0.13-0.14%, Fe content is 0.33-0.35%, Cu content is 1.53-1.54%, Mn content is ≤0.10%, Mg content is 2.4-2.55%, Cr content is 0.22-0.24%, Zn content is 5.7-5.8%, Ti content is 0.03-0.04%, the individual content of other impurities is ≤0.03%, the total content is ≤0.12%, and the balance is Al and unavoidable impurities.

3. The method for producing 7075 aluminum alloy by electrolyzing raw aluminum liquid according to claim 1, characterized in that: The aluminum content in the electrolytic aluminum liquid in step (1) is ≥99.85%.

4. The method for producing 7075 aluminum alloy by electrolyzing raw aluminum liquid according to claim 1, characterized in that: The feeding temperature of step (2) is 745-755°C.

5. The method for producing 7075 aluminum alloy by electrolyzing raw aluminum liquid according to claim 1, characterized in that: The soaking time in step (2) is 20 to 25 minutes; the electromagnetic stirring time is 10 to 15 minutes.

6. The method for producing 7075 aluminum alloy by electrolyzing raw aluminum liquid according to claim 1, characterized in that: In step (5), the amount of titanium block added is 2-2.2 kg / t.Al; the amount of 3% aluminum-beryllium master alloy added is 0.25-0.3 kg / t; and the mass ratio of the cold material added is ≥30%.

7. The method for producing 7075 aluminum alloy by electrolyzing raw aluminum liquid according to claim 1, characterized in that: The specific steps of refining in step (6) are: first, manually refine in a chlorine-argon mixed gas for 20 to 25 minutes, and then open the air brick and use argon to refine for 20 to 25 minutes; the volume proportion of chlorine in the mixed gas is 2%, and the volume proportion of argon is 98%.

8. The method for producing 7075 aluminum alloy by electrolyzing raw aluminum liquid according to claim 1, characterized in that: The filtration in step (6) is firstly carried out by plate type coarse filtration using a 584*584mm, 40ppm ceramic filter disc, and then the melt is purified by secondary filtration in a deep bed filtration with a circulation filtration accuracy of 10-20μm; the empty box insulation temperature of the filter box for the two filtrations is 730-750°C, the furnace temperature of the filter box is set to 850°C, the insulation temperature of the filter box with material is 720-740°C, and the furnace temperature of the filter box is set to 800°C.

9. The method for producing 7075 aluminum alloy by electrolyzing raw aluminum liquid according to claim 1, characterized in that: The casting speed in the casting process of step (7) is 40-45 mm / min; the flow rate of casting cooling water is 800-1500 L / min; The tempering temperature is 650-750° C. and the tempering time is 30-60 min.

10. The method for producing 7075 aluminum alloy by electrolyzing raw aluminum liquid according to claim 1, characterized in that: The specific method of the homogenization annealing in step (8) is: First, heat to 180°C at a rate of 100°C / h, keep warm for 1 hour, then continue to heat by 100°C at a rate of 100°C / h, and keep warm for 1 hour. After multiple heating and keeping warm, heat to 460-480°C, and then keep warm for 40 hours.

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