Aluminum alloy flat cast ingot for aviation and preparation method thereof

Abstract

The invention relates to an aviation aluminum alloy flat cast ingot and a preparation method thereof, in particular to an aviation aluminum alloy flat cast ingot and a preparation method thereof. The invention aims to solve the problem of low yield of the existing Al-Fe-Mn series aviation aluminum alloy flat cast ingot. The cast ingot is prepared from, by mass, less than 0.30% of Si, 1.2%-1.6% of Fe, less than 0.20% of Cu, 0.2%-0.6% of Mn, less than 0.10% of Mg, less than 0.10% of Zn, less than 0.10% of Ti and the balance aluminum as smelting raw materials. The method comprises the following steps: 1, weighing smelting raw materials; 2, smelting the smelting raw materials in sequence; and 3, casting the alloy melt in a natural gas furnace to obtain the aluminum alloy flat cast ingot. According to the invention, the existing casting process is optimized, so that the yield of cast ingots reaches 88%.

Description

Technical Field

[0001] The present invention specifically relates to an aluminum alloy flat ingot for aviation and a preparation method thereof. Background Art

[0002] Al-Fe-Mn series aviation aluminum alloy flat ingots have a strength close to that of high-quality steel, good plasticity, can be processed into various profiles, have good electrical conductivity, thermal conductivity and corrosion resistance, and are widely used in industry. However, due to the high Fe content, the alloy shows a great tendency to crack during casting, the range of melting and casting process parameters is extremely narrow, cracked waste often appears during the casting process, the melt purity control is difficult, the flaw detection pass rate is also relatively low, and the ingot finished product rate is only 70%. Summary of the invention

[0003] The present invention aims to solve the problem of low yield of existing Al-Fe-Mn series aviation aluminum alloy flat ingots, and provides an aviation aluminum alloy flat ingot and a preparation method thereof.

[0004] The aviation aluminum alloy flat ingot of the present invention comprises Si less than 0.30%, Fe: 1.2%-1.6%, Cu less than 0.20%, Mn: 0.2%-0.6%, Mg less than 0.10%, Zn less than 0.10%, Ti less than 0.10% and the balance of aluminum in percentage by mass.

[0005] The method for preparing an aviation aluminum alloy flat ingot of the present invention is completed by the following steps:

[0006] 1. According to the mass percentage of Si less than 0.30%, Fe: 1.2% to 1.6%, Cu less than 0.20%, Mn: 0.2% to 0.6%, Mg less than 0.10%, Zn less than 0.10%, Ti less than 0.10% and the balance of aluminum, weigh aluminum ingots, Al-Fe master alloys, and Al-Mn master alloys as smelting raw materials;

[0007] 2. Melting the smelting raw materials weighed in step 1, the order of adding the smelting raw materials is: first adding the aluminum ingot, then adding the Al-Fe master alloy and the Al-Mn master alloy, stirring for 15 to 25 minutes at a temperature of 700 to 750° C., sampling and analyzing the chemical composition, and after the chemical composition is qualified, covering with flux to obtain an alloy melt;

[0008] 3. The alloy melt obtained in step 2 is introduced into a static furnace at a temperature of 700-750°C, and argon is introduced for refining for 30 minutes and then allowed to stand for 25-35 minutes to obtain a refined alloy melt. The refined alloy melt first flows into an online degassing device, then flows into a filtering device, and then flows through a flow plate at a casting speed of 50-60 mm / min, a temperature before the baffle of 690-710°C, and a cooling water flow rate of 130-170 m3 / h, the crystallizer liquid level height is 75-95mm, and the melt is injected into the crystallizer under the conditions of online seeding of Al-5Ti-0.2B wire, and semi-continuous casting is carried out to obtain aviation aluminum alloy flat ingots.

[0009] Beneficial effects of the present invention:

[0010] The present invention can effectively remove H2 in the melt by having the melt flow into an online degassing device; can effectively remove slag by having the melt flow into a filtering device; can reduce the tendency of the ingot to shut down by increasing the initial casting speed and the liquid level; can reduce the tendency of aluminum leakage at the initial stage by increasing the initial water flow rate; and can improve the yield rate of the ingots obtained by the above method to 88%, thereby solving the problem of low yield rate of the ingots prepared by the existing method. DETAILED DESCRIPTION

[0011] 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.

[0012] Specific implementation method 1: In this implementation method, the aviation aluminum alloy flat ingot is composed of Si less than 0.30%, Fe: 1.2%~1.6%, Cu less than 0.20%, Mn: 0.2%~0.6%, Mg less than 0.10%, Zn less than 0.10%, Ti less than 0.10% and the balance aluminum in percentage by mass.

[0013] Adding a small amount of Ti and B can significantly refine the alloy grains and reduce the crack tendency of the alloy.

[0014] Si, Cu, Mg and Zn are all impurity elements. In actual production, the lower their content, the better.

[0015] In this embodiment, the smelting raw materials are aluminum ingots, Al-Fe master alloys and Al-Mn master alloys.

[0016] Specific embodiment 2: This embodiment is different from the specific embodiment 1 in that the aviation aluminum alloy flat ingot is composed of Si less than 0.30%, Fe: 1.3%, Cu less than 0.20%, Mn: 0.5%, Mg less than 0.1%, Zn less than 0.10%, Ti less than 0.10% and the balance of aluminum in terms of mass percentage. Other steps and parameters are the same as those of the specific embodiment 1.

[0017] Specific implementation method three: In this implementation method, a method for preparing an aviation aluminum alloy flat ingot is completed by the following steps:

[0018] 1. According to the mass percentage of Si less than 0.30%, Fe: 1.2% to 1.6%, Cu less than 0.20%, Mn: 0.2% to 0.6%, Mg less than 0.10%, Zn less than 0.10%, Ti less than 0.10% and the balance of aluminum, weigh aluminum ingots, Al-Fe master alloys, and Al-Mn master alloys as smelting raw materials;

[0019] 2. Melting the smelting raw materials weighed in step 1, the order of adding the smelting raw materials is: first adding the aluminum ingot, then adding the Al-Fe master alloy and the Al-Mn master alloy, stirring for 15 to 25 minutes at a temperature of 700 to 750° C., sampling and analyzing the chemical composition, and after the chemical composition is qualified, covering with flux to obtain an alloy melt;

[0020] 3. The alloy melt obtained in step 2 is introduced into a static furnace at a temperature of 700-750°C, and argon is introduced for refining for 30 minutes and then allowed to stand for 25-35 minutes to obtain a refined alloy melt. The refined alloy melt first flows into an online degassing device, then flows into a filtering device, and then flows through a flow plate at a casting speed of 50-60 mm / min, a temperature before the baffle of 690-710°C, and a cooling water flow rate of 130-170 m 3 / h, the crystallizer liquid level height is 75-95mm, and the melt is injected into the crystallizer under the conditions of online seeding of Al-5Ti-0.2B wire, and semi-continuous casting is carried out to obtain aviation aluminum alloy flat ingots.

[0021] This embodiment reduces the crack tendency of the flat ingot by controlling the process parameters, solves the crack defects on the surface of the ingot and improves the purity of the melt, so as to improve the yield of the ingot.

[0022] In step 2 of this embodiment, the Al-Fe master alloy and the Al-Mn master alloy are added after the melt is melted and reaches 720° C. The stirring of the melt in this step is stirring at 730° C. for 20 minutes, and the stirring is performed by electromagnetic stirring.

[0023] Specific implementation method 4: This implementation method is different from specific implementation method 3 in that the purity of the aluminum ingot in step 1 is 99.7%. Other steps and parameters are the same as those in specific implementation method 3.

[0024] Specific embodiment 5: This embodiment differs from specific embodiment 4 in that: in step 1, the Fe content of the Al-Fe master alloy is 10%, and the rest is Al; the Mn content of the Al-Mn master alloy is 10%, and the rest is Al. Other steps and parameters are the same as those of specific embodiment 3.

[0025] Specific embodiment 6: This embodiment is different from specific embodiment 3 in that: in step 1, aluminum ingots, Al-Fe master alloys, and Al-Mn master alloys are weighed as smelting raw materials according to the mass percentage of Si less than 0.30%, Fe: 1.3%, Cu less than 0.20%, Mn: 0.5%, Mg less than 0.1%, Zn less than 0.10%, Ti less than 0.10%, and the balance of aluminum. Other steps and parameters are the same as those of specific embodiment 3.

[0026] Specific embodiment 7: This embodiment differs from specific embodiment 3 in that the stirring of the melt is performed by electromagnetic stirring. The other steps and parameters are the same as those of specific embodiment 3.

[0027] Specific implementation method 8: This implementation method is different from specific implementation method 3 in that a slag scraper is used for stirring. Other steps and parameters are the same as those of specific implementation method 3.

[0028] Specific embodiment 9: This embodiment differs from specific embodiment 3 in that: in step 2, stirring is performed at 730° C. for 20 minutes. Other steps and parameters are the same as those in specific embodiment 3.

[0029] Specific embodiment 10: This embodiment differs from specific embodiment 3 in that: the flux in step 2 is composed of 40% KCl, 45% MgCl2, 8% BaCl2, and 7% NaCl+CaCl2 by mass percentage, and the added amount is 2 kg / ton of melt. The other steps and parameters are the same as those in specific embodiment 3.

[0030] Specific embodiment 11: This embodiment differs from specific embodiment 3 in that the composition of the argon gas introduced in step 3 is 99.99% argon gas. The other steps and parameters are the same as those in specific embodiment 3.

[0031] Specific embodiment 12: This embodiment differs from specific embodiment 3 in that the rate of introducing argon in step 3 is 0.20-0.25 m / s. 3 / min. Other steps and parameters are the same as those in the third specific implementation mode.

[0032] Specific implementation thirteen: This implementation differs from specific implementation three in that: in step three, the melt first flows into an online degassing device during casting, and the gas purity in the degassing device is 99.99% argon. Other steps and parameters are the same as those of specific implementation three.

[0033] Specific embodiment 14: This embodiment differs from specific embodiment 3 in that the precision of the ceramic sheet in the filtering device in step 3 is 30 meshes + 50 meshes. The other steps and parameters are the same as those in specific embodiment 3.

[0034] Specific embodiment 15: This embodiment differs from specific embodiment 3 in that: in step 3, the casting speed is 55 mm / min, the casting temperature is 705°C, and the casting cooling water flow rate is 150 m / min. 3 / h, and the crystallizer liquid level is 90mm. The other steps and parameters are the same as those in the third embodiment.

[0035] Specific embodiment 16: This embodiment differs from specific embodiment 3 in that the Ti content of the online seeded Al-5Ti-0.2B wire in step 3 is 5%, the B content is 0.2%, and the rest is Al, and the seeding speed is 420 mm / min per ingot. The other steps and parameters are the same as those in specific embodiment 3.

[0036] Specific embodiment 17: This embodiment differs from specific embodiment 3 in that the shape of the crystallizer into which the melt is injected in step 3 is a rectangle of 420 mm×1320 mm. The other steps and parameters are the same as those in specific embodiment 3.

[0037] Specific embodiment 18: This embodiment differs from specific embodiment 3 in that the ingot starter for injecting the melt into the crystallizer in step 3 is in the shape of a flat arc of 420 mm×1320 mm. Other steps and parameters are the same as those in specific embodiment 3.

[0038] Specific embodiment 19: This embodiment differs from specific embodiment 3 in that the size of the aviation aluminum alloy flat ingot obtained by semi-continuous casting in step 3 is 420mm×1320mm×(3000mm~7000mmmm). Other steps and parameters are the same as those in specific embodiment 3.

[0039] The following examples are used to verify the beneficial effects of the present invention:

[0040] Embodiment 1: The manufacturing method of the industrial aluminum alloy flat ingot of this embodiment is implemented by the following steps:

[0041] 1. Weigh aluminum ingots, Al-Fe master alloys, and Al-Mn master alloys as smelting raw materials according to the mass percentage of Si less than 0.30%, Fe: 1.3%, Cu less than 0.20%, Mn: 0.5%, Mg less than 0.1%, Zn less than 0.10%, Ti less than 0.10%, and the balance of aluminum;

[0042] 2. Melting the smelting raw materials weighed in step 1, the order of adding the smelting raw materials is: first adding the aluminum ingot, then adding the Al-Fe master alloy and the Al-Mn master alloy, stirring for 20 minutes at a temperature of 710° C., sampling and analyzing the chemical composition, and after the chemical composition is qualified, covering with flux to obtain an alloy melt;

[0043] 3. The alloy melt obtained in step 2 is introduced into a static furnace at a temperature of 740°C, and argon is introduced for refining for 30 minutes and then allowed to stand for 30 minutes to obtain a refined alloy melt. The refined alloy melt first flows into an online degassing device, then flows into a filtering device, and then passes through a flow plate at a casting speed of 55 mm / min, a temperature before the baffle of 705°C, and a cooling water flow rate of 150 m 3 / h, a crystallizer liquid level of 90 mm, and online seeding of Al-5Ti-0.2B wires were injected into the crystallizer, and semi-continuous casting was performed to obtain aviation aluminum alloy flat ingots.

[0044] The chemical composition of the aluminum alloy flat ingot for aviation obtained in the first embodiment is qualified, and there are no defects such as cracks and slag inclusions on the surface, and the yield rate reaches 89%.

[0045] Embodiment 2: The manufacturing method of the hollow aluminum alloy ingot for aircraft fuselage of this embodiment is implemented by the following steps:

[0046] 1. Weigh aluminum ingots, Al-Fe master alloys, and Al-Mn master alloys as smelting raw materials according to the mass percentage of Si less than 0.30%, Fe: 1.5%, Cu less than 0.20%, Mn: 0.4%, Mg less than 0.1%, Zn less than 0.10%, Ti less than 0.10%, and the balance of aluminum;

[0047] 2. Melting the smelting raw materials weighed in step 1, the order of adding the smelting raw materials is: first adding the aluminum ingot, then adding the Al-Fe master alloy and the Al-Mn master alloy, stirring for 25 minutes at a temperature of 730° C., sampling and analyzing the chemical composition, and after the chemical composition is qualified, covering with flux to obtain an alloy melt;

[0048] 3. The alloy melt obtained in step 2 is introduced into a static furnace at a temperature of 745°C, and argon is introduced for refining for 30 minutes and then allowed to stand for 30 minutes to obtain a refined alloy melt. The refined alloy melt first flows into an online degassing device, then flows into a filtering device, and then flows through a flow plate at a casting speed of 60 mm / min, a temperature before the baffle of 710°C, and a cooling water flow rate of 160 m 3 / h, a crystallizer liquid level of 95 mm, and online seeding of Al-5Ti-0.2B wires were injected into the crystallizer, and semi-continuous casting was performed to obtain aviation aluminum alloy flat ingots.

[0049] In the second embodiment, the chemical composition of the aluminum alloy flat ingot for aviation use is qualified, there are no defects such as cracks and slag inclusions on the surface, and the yield rate reaches 83%.

Claims

1. A flat ingot of aluminum alloy for aviation, characterized in that The aviation aluminum alloy flat ingot is composed of Si less than 0.30%, Fe: 1.2% to 1.6%, Cu less than 0.20%, Mn: 0.2% to 0.6%, Mg less than 0.10%, Zn less than 0.10%, Ti less than 0.10% and the balance of aluminum in percentage by mass.

2. The aluminum alloy flat ingot for aviation use according to claim 1, characterized in that The aviation aluminum alloy flat ingot is composed of Si less than 0.30%, Fe: 1.2% to 1.6%, Cu less than 0.20%, Mn: 0.2% to 0.6%, Mg less than 0.10%, Zn less than 0.10%, Ti less than 0.10% and the balance of aluminum in percentage by mass.

3. A method for preparing an aluminum alloy flat ingot for aviation use, characterized in that The preparation method of aluminum alloy flat ingot for aviation is completed in the following steps:

1. According to the mass percentage of Si less than 0.30%, Fe: 1.2% to 1.6%, Cu less than 0.20%, Mn: 0.2% to 0.6%, Mg less than 0.10%, Zn less than 0.10%, Ti less than 0.10% and the balance of aluminum, weigh aluminum ingots, Al-Fe master alloys, and Al-Mn master alloys as smelting raw materials; 2. Melting the smelting raw materials weighed in step 1, the order of adding the smelting raw materials is: first adding the aluminum ingot, then adding the Al-Fe master alloy and the Al-Mn master alloy, stirring for 15 to 25 minutes at a temperature of 700 to 750° C., sampling and analyzing the chemical composition, and after the chemical composition is qualified, covering with flux to obtain an alloy melt; 3. The alloy melt obtained in step 2 is introduced into a static furnace at a temperature of 700-750°C, and argon is introduced for refining for 30 minutes and then allowed to stand for 25-35 minutes to obtain a refined alloy melt. The refined alloy melt first flows into an online degassing device, then flows into a filtering device, and then flows through a flow plate at a casting speed of 50-60 mm / min, a temperature before the baffle of 690-710°C, and a cooling water flow rate of 130-170 m 3 / h, the crystallizer liquid level height is 75-95mm, and the melt is injected into the crystallizer under the conditions of online seeding of Al-5Ti-0.2B wire, and semi-continuous casting is carried out to obtain aviation aluminum alloy flat ingots.

4. The method for preparing an aviation aluminum alloy flat ingot according to claim 3, characterized in that In step 1, the Fe content in the Al-Fe master alloy is 10%, and the rest is Al; the Mn content in the Al-Mn master alloy is 10%, and the rest is Al.

5. The method for preparing an aviation aluminum alloy flat ingot according to claim 3, characterized in that In step 2, the mixture is stirred at 730° C. for 20 min.

6. The method for preparing an aviation aluminum alloy flat ingot according to claim 3, characterized in that The flux in step 2 is composed of 40% KCl, 45% MgCl2, 8% BaCl2, and 7% NaCl+CaCl2 in mass percentage, and the added amount is 2 kg / ton of melt.

7. The method for preparing an aviation aluminum alloy flat ingot according to claim 3, characterized in that The rate of introducing argon in step 3 is 0.20-0.25 m / s. 3 / min.

8. The method for preparing an aviation aluminum alloy flat ingot according to claim 3, characterized in that The precision of the ceramic sheet in the filtering device in step three is 30 mesh + 50 mesh.

9. The method for preparing an aviation aluminum alloy flat ingot according to claim 3, characterized in that In step 3, the casting speed is 55 mm / min, the temperature before the baffle is 705 °C, and the cooling water flow rate is 150m 3 / h, the crystallizer liquid level height is 90mm, and the melt is injected into the crystallizer under the conditions of online seeding of Al-5Ti-0.2B wire.

10. The method for preparing an aviation aluminum alloy flat ingot according to claim 3, characterized in that In step 3, the online seeding of Al-5Ti-0.2B wire has a Ti content of 5%, a B content of 0.2%, and the remainder is Al, and the seeding speed is 420 mm / min per ingot.