Manufacturing method of Al-Zn-Mg-Cu series aluminum alloy flat cast ingot

Abstract

The invention discloses a manufacturing method of an Al-Zn-Mg-Cu series aluminum alloy flat cast ingot, and belongs to the field of wrought aluminum alloy casting. The method solves the problems of high crack tendency and low casting yield in the existing production of the composite core material aluminum alloy with higher Ti content. The method comprises the following steps: 1, weighing; 2, smelting; 3, preparing a casting melt; and fourthly, a double-drainage crystallizer is adopted for semi-continuous casting forming. The crystallizer for semi-continuous casting adopts a double-drainage cooling mode, is matched with a double-curved-surface base and adopts casting process parameters of high casting speed and low water flow at the beginning of casting, shortening the distance between a water retaining rubber plate and the lower edge of the crystallizer, reducing the casting speed and high water flow after stable casting, and prolonging the distance between the water retaining rubber plate and the lower edge of the crystallizer; the defects of aluminum leakage, suspension, cold cracks and the like at the casting head are effectively overcome, and forming is guaranteed. The flat cast ingot manufactured through the method is free of cracks, the surface of the cast ingot is smooth, and the metallographic structure is free of the defects of looseness, slag inclusion and the like; and the yield of cast ingots is greater than 90%.

Description

Technical Field

[0001] The invention belongs to the field of deformed aluminum alloy casting, and in particular relates to a method for manufacturing an Al-Zn-Mg-Cu series aluminum alloy flat ingot. Background Art

[0002] Composite core aluminum alloy has a series of outstanding advantages such as high strength, strong resistance to exfoliation corrosion, stress corrosion cracking, excellent fracture toughness and fatigue resistance, and has important application value in automobiles. The existing composite core aluminum alloy with high Ti content has a strong tendency to crack, and it is very easy to produce cracked waste during the casting process, and even aluminum leakage at the beginning of casting causes aluminum liquid splashing and safety accidents. The casting yield is extremely low, and its ingot yield is only 80%. In order to improve the ingot yield and production efficiency and meet the needs of composite profile processing, studying a new composite core aluminum alloy flat ingot operation process is the key to promoting the application of composite core aluminum alloy. Summary of the invention

[0003] The purpose of the present invention is to solve the problems of large crack tendency and low casting yield of the existing composite core aluminum alloy with high Ti content, and to provide a method for manufacturing Al-Zn-Mg-Cu aluminum alloy flat ingot.

[0004] A method for manufacturing an Al-Zn-Mg-Cu aluminum alloy flat ingot is carried out according to the following steps:

[0005] 1. Weighing materials: according to the mass percentage of Cu: 1.70% ~ 2.30%, Mg: 1.50% ~ 2.30%, Zn: 7.20% ~ 8.50%, Zr: 0.05% ~ 0.15%, Si ≤ 0.06%, Fe ≤ 0.08%, Mn ≤ 0.04%, Cr ≤ 0.04%, Ti ≤ 0.06% and the balance of Al, weigh refined aluminum ingots, copper metal, magnesium metal, zinc metal, Al-Zr master alloy, Al-Ti master alloy;

[0006] 2. Melting: Add the above refined aluminum ingot and Al-Zr master alloy into a natural gas melting furnace, add copper metal and zinc metal after the refined aluminum ingot is melted, add magnesium metal and Al-Ti master alloy after heating to 730-750°C, stir by electromagnetic for 20-30 minutes, take samples for chemical composition analysis and obtain aluminum alloy melt after passing the test;

[0007] 3. Preparation of casting melt: The above aluminum alloy melt is introduced into a holding furnace at 730-750° C., and then argon-chlorine mixed gas is introduced for refining for 30 minutes, and then allowed to stand for 30 minutes to obtain a casting melt;

[0008] 4. Molding: The above-mentioned casting melt flows into the online double degassing device, and then flows into the filtering device. After filtering, it is injected into the crystallizer through the flow plate. The casting speed adopted from the semi-continuous casting to the casting reaching a length of 400mm is 55-60mm / min, the casting water flow rate is 20-30m3 / h per ingot, and the distance between the position of the water retaining rubber plate and the lower edge of the crystallizer is 190mm. When the casting reaches a length of 400mm, the casting speed adopted is 40-55mm / min, the casting water flow rate is 30-40m3 / h per ingot, and the distance between the position of the water retaining rubber plate and the lower edge of the crystallizer is 300mm-400mm. At the same time, Al-3Ti-0.15C wire is sown into the casting melt at a speed of 123mm / min per ingot to obtain Al-Zn-Mg-Cu aluminum alloy flat ingots, thereby completing the manufacturing method.

[0009] Furthermore, the mass purity of the refined aluminum ingot in step 1 is ≥99.99%, the Al-Zr master alloy is Al-3% Zr, and the Al-Ti master alloy is Al-6% Ti.

[0010] Furthermore, when the magnesium metal is added in step 2, an Al-Be master alloy with a mass content of 0.025% is added at the same time, and the amount of the Al-Be master alloy used is 0.25 kg per ton of aluminum alloy melt.

[0011] Furthermore, in the argon-chlorine mixed gas in step 3, the molar contents of argon and chlorine are 94% and 6% respectively.

[0012] Furthermore, the filtering device in step 4 uses a 30ppi+50ppi ceramic filter plate for filtering.

[0013] Furthermore, the crystallizer described in step 4: the crystallizer adopts a double drainage cooling method, and the shape and size of the crystallizer is a rectangle of 420mm×1320mm.

[0014] Furthermore, in step 4, the casting temperature is 685-705°C, and the temperature of cooling water used in casting is 18-26°C.

[0015] Furthermore, the Al-3Ti-0.15C wire in step 4 is used as a grain refiner in an amount of 3-4 kg per ton of casting melt.

[0016] Furthermore, the online double degassing device described in step 4 uses argon gas with a gas flow rate of 20 to 35 nm. 3 / hr, the speed is 350rpm / min, and the purity of argon is ≥99.996%.

[0017] Advantages of the present invention:

[0018] 1. The present invention uses an advanced water cooling control system to provide a stable water flow for casting. The crystallizer used for semi-continuous casting adopts a double drainage cooling method, and is matched with a hyperbolic base and adopts high casting speed, low water flow, and shortened distance between the water retaining rubber plate and the lower edge of the crystallizer at the beginning of casting. After the casting is stable, the casting speed is reduced, the water flow is high, and the casting process parameters of the distance between the water rubber plate and the lower edge of the crystallizer are extended. This effectively solves the defects of aluminum leakage, hanging, cold cracks, etc. at the beginning of casting, and ensures molding.

[0019] 2. The present invention adopts low-speed casting in the semi-continuous casting process, which effectively ensures the steady-state forming of the ingot; an automatic lubrication system is used in the semi-continuous casting process to provide stable oil supply for the casting ingot, ensuring lubrication and avoiding scratches and cracks; electromagnetic stirring is used to stir the melt in the smelting process to ensure the uniformity of the melt composition and temperature, and a 30ppi+50ppi two-stage ceramic filter is used in the casting process to filter the melt to effectively remove inclusions in the melt and ensure the purification effect.

[0020] 3. The Al-Zn-Mg-Cu aluminum alloy flat ingot prepared by the method of the present invention has a thickness of 420 mm, a width of 1320 mm, a length of 4000-7000 mm, no cracks, and a smooth surface of the ingot, and the metallographic structure has no defects such as looseness and slag inclusions; the ingot yield rate is greater than 90%.

[0021] The invention is suitable for manufacturing Al-Zn-Mg-Cu series aluminum alloy flat ingots. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 : is the metallographic structure diagram of the Al-Zn-Mg-Cu aluminum alloy flat ingot produced in the embodiment;

[0023] Figure 2 This is a physical picture of the Al-Zn-Mg-Cu aluminum alloy flat ingot produced in the example. DETAILED DESCRIPTION

[0024] The technical solution of the present invention is not limited to the specific implementation modes listed below, but also includes any combination of the specific implementation modes.

[0025] Specific implementation method 1: This implementation method is a method for manufacturing an Al-Zn-Mg-Cu aluminum alloy flat ingot, which is carried out according to the following steps:

[0026] 1. Weighing materials: according to the mass percentage of Cu: 1.70% ~ 2.30%, Mg: 1.50% ~ 2.30%, Zn: 7.20% ~ 8.50%, Zr: 0.05% ~ 0.15%, Si ≤ 0.06%, Fe ≤ 0.08%, Mn ≤ 0.04%, Cr ≤ 0.04%, Ti ≤ 0.06% and the balance of Al, weigh refined aluminum ingots, copper metal, magnesium metal, zinc metal, Al-Zr master alloy, Al-Ti master alloy;

[0027] 2. Melting: Add the above refined aluminum ingot and Al-Zr master alloy into a natural gas melting furnace, add copper metal and zinc metal after the refined aluminum ingot is melted, add magnesium metal and Al-Ti master alloy after heating to 730-750°C, stir by electromagnetic for 20-30 minutes, take samples for chemical composition analysis and obtain aluminum alloy melt after passing the test;

[0028] 3. Preparation of casting melt: The above aluminum alloy melt is introduced into a holding furnace at 730-750° C., and then argon-chlorine mixed gas is introduced for refining for 30 minutes, and then allowed to stand for 30 minutes to obtain a casting melt;

[0029] 4. Molding: The above-mentioned casting melt flows into the online double degassing device, and then flows into the filtering device. After filtering, it is injected into the crystallizer through the flow plate. The casting speed adopted from the semi-continuous casting to the casting reaching a length of 400mm is 55-60mm / min, the casting water flow rate is 20-30m3 / h per ingot, and the distance between the position of the water retaining rubber plate and the lower edge of the crystallizer is 190mm. When the casting reaches a length of 400mm, the casting speed adopted is 40-55mm / min, the casting water flow rate is 30-40m3 / h per ingot, and the distance between the position of the water retaining rubber plate and the lower edge of the crystallizer is 300mm-400mm. At the same time, Al-3Ti-0.15C wire is sown into the casting melt at a speed of 123mm / min per ingot to obtain Al-Zn-Mg-Cu aluminum alloy flat ingots, thereby completing the manufacturing method.

[0030] In step 1 of this embodiment, Si, Fe, Mn and Cr are all impurity elements. Impurities within this range have no effect on the forming and metallurgical quality of the ingot. In actual production, the lower the content, the better.

[0031] The purpose of sampling and analyzing the chemical composition and passing the test in step 2 of this embodiment is to obtain a qualified aluminum alloy melt, whose chemical composition meets the mass percentage of Cu: 1.70% ~ 2.30%, Mg: 1.50% ~ 2.30%, Zn: 7.20% ~ 8.50%, Zr: 0.05% ~ 0.15%, Si ≤ 0.06%, Fe ≤ 0.08%, Mn ≤ 0.04%, Cr ≤ 0.04%, Ti ≤ 0.06% and the remainder Al.

[0032] In step 2 of this embodiment, electromagnetic stirring is performed to perform convection stirring in the middle of the furnace bottom.

[0033] Specific embodiment 2: This embodiment is different from the specific embodiment 1 in that in step 1, the mass percentages are Cu: 1.80%, Mg: 2.0%, Zn: 8.05%, Zr: 0.11%, Si≤0.06%, Fe≤0.08%, Mn≤0.04%, Cr≤0.04%, Ti≤0.06% and the balance is Al. The other steps and parameters are the same as those in the specific embodiment 1.

[0034] Specific implementation method 3: This implementation method is different from specific implementation method 1 in that the mass purity of the refined aluminum ingot in step 1 is ≥99.99%, the Al-Zr master alloy is Al-3%Zr, and the Al-Ti master alloy is Al-6%Ti. Other steps and parameters are the same as those in specific implementation method 1.

[0035] Specific embodiment 4: This embodiment differs from specific embodiment 1 in that when magnesium metal is added in step 2, an Al-Be master alloy with a mass content of 0.025% is added at the same time, and the amount of Al-Be master alloy used is 0.25 kg / ton of aluminum alloy melt. Other steps and parameters are the same as those of specific embodiment 1.

[0036] In this embodiment, the Al-Be master alloy is added to improve the structure of the aluminum alloy oxide film to prevent the oxidation and burning of magnesium and aluminum elements and the generation of oxides to contaminate the melt.

[0037] Specific implementation mode 5: This implementation mode is different from specific implementation mode 1 in that the molar contents of argon and chlorine in the argon-chlorine mixed gas in step 3 are 94% and 6% respectively. Other steps and parameters are the same as those in specific implementation mode 1.

[0038] Specific implementation example 6: This implementation example is different from specific implementation example 1 in that the filtering device in step 4 uses a 30ppi+50ppi ceramic filter sheet for filtering. Other steps and parameters are the same as those in specific implementation example 1.

[0039] Specific implementation example 7: This implementation example is similar to the specific implementation example in that the crystallizer in step 4: the crystallizer adopts a double drainage cooling method, and the shape and size of the crystallizer is a rectangle of 420 mm×1320 mm. Other steps and parameters are the same as those in specific implementation example 1.

[0040] Specific embodiment eight: This embodiment differs from specific embodiment one in that the casting temperature in step four is 685-705° C., and the temperature of the cooling water used for casting is 18-26° C. The other steps and parameters are the same as those in specific embodiment one.

[0041] Specific embodiment 9: This embodiment is different from specific embodiment 1 in that the Al-3Ti-0.15C wire in step 4 is used as a grain refiner in an amount of 3-4 kg / ton of casting melt. Other steps and parameters are the same as those in specific embodiment 1.

[0042] Specific embodiment 10: This embodiment is different from the specific embodiment 1 in that the online double degassing device in step 4 uses argon gas, and the argon gas flow rate is 20-35nm 3 / hr, the speed is 350rpm / min, and the purity of argon is ≥99.996%. Other steps and parameters are the same as those in the first embodiment.

[0043] The beneficial effects of the present invention are verified by the following examples:

[0044] Example:

[0045] A method for manufacturing an Al-Zn-Mg-Cu aluminum alloy flat ingot is carried out according to the following steps:

[0046] 1. Weighing materials: according to the mass percentage of Cu: 1.80%, Mg: 2.0%, Zn: 8.05%, Zr: 0.11%, Si≤0.06%, Fe≤0.08%, Mn≤0.04%, Cr≤0.04%, Ti≤0.06% and the balance of Al, weigh refined aluminum ingots, pure copper plates, pure magnesium ingots, pure zinc ingots, Al-Zr master alloys, and Al-Ti master alloys;

[0047] 2. Melting: Add the above refined aluminum ingot and Al-Zr master alloy into a natural gas melting furnace, add pure copper plate and pure zinc ingot after the refined aluminum ingot is melted, add pure magnesium ingot and Al-Ti master alloy after heating to 730°C, stir by electromagnetic for 20-30 minutes, take samples for chemical composition analysis and obtain aluminum alloy melt after passing the test;

[0048] 3. Preparation of casting melt: The above aluminum alloy melt is introduced into a holding furnace at 730-750° C., and then argon-chlorine mixed gas is introduced for refining for 30 minutes, and then allowed to stand for 30 minutes to obtain a casting melt;

[0049] 4. Molding: The above-mentioned casting melt flows into the online double degassing device, and then flows into the filtering device. After filtering, it is injected into the crystallizer through the flow plate. The casting speed adopted from the semi-continuous casting to the casting reaching a length of 400mm is 55mm / min, the casting water flow rate is 20m3 / h per ingot, and the distance between the position of the water retaining rubber plate and the lower edge of the crystallizer is 190mm. When the casting reaches a length of 400mm, the casting speed adopted is 40mm / min, the casting water flow rate is 35m3 / h per ingot, and the distance between the position of the water retaining rubber plate and the lower edge of the crystallizer is 350mm. At the same time, Al-3Ti-0.15C wire is seeded into the casting melt at a speed of 123mm / min per ingot to obtain Al-Zn-Mg-Cu aluminum alloy flat ingots, thereby completing the manufacturing method.

[0050] The mass purity of the refined aluminum ingot in step 1 of this embodiment is ≥99.99%, the Al-Zr master alloy is Al-3% Zr, and the Al-Ti master alloy is Al-6% Ti.

[0051] In step 2 of this embodiment, when adding magnesium metal, Al-Be master alloy with a mass content of 0.025% is added at the same time, and the amount of Al-Be master alloy used is 0.25 kg per ton of aluminum alloy melt.

[0052] In step 3 of this embodiment, the argon-chlorine mixed gas has molar contents of argon and chlorine of 94% and 6% respectively.

[0053] The filtering device described in step 4 of this embodiment: uses 30ppi+50ppi ceramic filter plates for filtering.

[0054] The crystallizer described in step 4 of this embodiment: the crystallizer adopts a double-drain cooling method, and the shape and size of the crystallizer is a rectangle of 420 mm×1320 mm.

[0055] The casting temperature in step 4 of this embodiment is 685-705°C, and the temperature of the cooling water used for casting is 18-26°C.

[0056] The Al-3Ti-0.15C wire described in step 4 of this embodiment is used as a grain refiner, and the amount used is 3.6 kg per ton of casting melt.

[0057] The online double degassing device in step 4 of this embodiment uses argon gas with a gas flow rate of 20 to 35 nm. 3 / hr, the speed is 350rpm / min, and the purity of argon is ≥99.996%.

[0058] The Al-Zn-Mg-Cu aluminum alloy flat ingot manufactured in this embodiment has a thickness of 420 mm, a width of 1320 mm, and a length of 4000 to 7000 mm; Figure 1As shown in the figure, the metallographic structure has no defects such as looseness and slag inclusion. Figure 2 As shown, there are no cracks, the ingot surface is smooth and well-formed, the internal performance is up to standard, the structure is not loose, and the finished product rate of the ingot is over 90%.

[0059] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for producing an Al-Zn-Mg-Cu aluminum alloy flat ingot, characterized in that It proceeds as follows:

1. Weighing materials: according to the mass percentage of Cu: 1.70% ~ 2.30%, Mg: 1.50% ~ 2.30%, Zn: 7.20% ~ 8.50%, Zr: 0.05% ~ 0.15%, Si ≤ 0.06%, Fe ≤ 0.08%, Mn ≤ 0.04%, Cr ≤ 0.04%, Ti ≤ 0.06% and the balance of Al, weigh refined aluminum ingots, copper metal, magnesium metal, zinc metal, Al-Zr master alloy, Al-Ti master alloy; 2. Melting: Add the above refined aluminum ingot and Al-Zr master alloy into a natural gas melting furnace, add copper metal and zinc metal after the refined aluminum ingot is melted, add magnesium metal and Al-Ti master alloy after heating to 730-750°C, stir by electromagnetic for 20-30 minutes, take samples for chemical composition analysis and obtain aluminum alloy melt after passing the test; 3. Preparation of casting melt: The above aluminum alloy melt is introduced into a holding furnace at 730-750° C., and then argon-chlorine mixed gas is introduced for refining for 30 minutes, and then allowed to stand for 30 minutes to obtain a casting melt; 4. Molding: The above-mentioned casting melt flows into the online double degassing device, and then flows into the filtering device. After filtering, it is injected into the crystallizer through the flow plate. The casting speed adopted from the semi-continuous casting to the casting reaching a length of 400mm is 55-60mm / min, the casting water flow rate is 20-30m3 / h per ingot, and the distance between the position of the water retaining rubber plate and the lower edge of the crystallizer is 190mm. When the casting reaches a length of 400mm, the casting speed adopted is 40-55mm / min, the casting water flow rate is 30-40m3 / h per ingot, and the distance between the position of the water retaining rubber plate and the lower edge of the crystallizer is 300mm-400mm. At the same time, Al-3Ti-0.15C wire is sown into the casting melt at a speed of 123mm / min per ingot to obtain Al-Zn-Mg-Cu aluminum alloy flat ingots, thereby completing the manufacturing method.

2. The method for manufacturing an Al-Zn-Mg-Cu aluminum alloy flat ingot according to claim 1, characterized in that In step 1, the mass percentages are Cu: 1.80%, Mg: 2.0%, Zn: 8.05%, Zr: 0.11%, Si≤0.06%, Fe≤0.08%, Mn≤0.04%, Cr≤0.04%, Ti≤0.06% and the balance Al.

3. The method for manufacturing an Al-Zn-Mg-Cu aluminum alloy flat ingot according to claim 1, characterized in that The mass purity of the refined aluminum ingot in step 1 is ≥99.99%, the Al-Zr master alloy is Al-3% Zr, and the Al-Ti master alloy is Al-6% Ti.

4. The method for manufacturing an Al-Zn-Mg-Cu aluminum alloy flat ingot according to claim 1, characterized in that When adding magnesium metal in step 2, an Al-Be master alloy with a mass content of 0.025% is added at the same time. The amount of the Al-Be master alloy used is 0.25 kg per ton of aluminum alloy melt.

5. The method for manufacturing an Al-Zn-Mg-Cu aluminum alloy flat ingot according to claim 1, characterized in that The argon-chlorine mixed gas in step 3 has molar contents of argon and chlorine of 94% and 6% respectively.

6. The method for manufacturing an Al-Zn-Mg-Cu aluminum alloy flat ingot according to claim 1, characterized in that The filtering device described in step 4: uses 30ppi+50ppi ceramic filter plates for filtering.

7. The method for manufacturing an Al-Zn-Mg-Cu aluminum alloy flat ingot according to claim 1, characterized in that The crystallizer described in step 4: the crystallizer adopts a double-drain cooling method, and the shape and size of the crystallizer is a rectangle of 420mm×1320mm.

8. The method for manufacturing an Al-Zn-Mg-Cu aluminum alloy flat ingot according to claim 1, characterized in that The casting temperature in step 4 is 685-705°C, and the cooling water temperature used in casting is 18-26°C.

9. The method for manufacturing an Al-Zn-Mg-Cu aluminum alloy flat ingot according to claim 1, characterized in that The Al-3Ti-0.15C wire described in step 4 is used as a grain refiner in an amount of 3 to 4 kg per ton of casting melt.

10. The method for manufacturing an Al-Zn-Mg-Cu aluminum alloy flat ingot according to claim 1, characterized in that The online double degassing device described in step 4: using argon gas, the argon gas flow rate is 20-35nm 3 / hr, the speed is 350rpm / min, and the purity of argon is ≥99.996%.

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