An aluminum alloy flat ingot for aircraft and a method for manufacturing the same

Abstract

The application relates to an aluminum alloy flat ingot for aviation and a preparation method thereof. The application is particularly related to an aluminum alloy flat ingot for aviation and a preparation method thereof. The application aims at solving the problem of low finished product rate of an Al-Fe-Mn system aluminum alloy flat ingot for aviation. The ingot is prepared by taking, as smelting raw materials, aluminum with the following mass percentage: 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. The method comprises the following steps: 1, weighing the smelting raw materials; 2, sequentially smelting the smelting raw materials; and 3, placing the alloy melt into a natural gas furnace to perform casting to obtain the aluminum alloy flat ingot. The application optimizes the existing smelting process, so that the finished product rate of the ingot reaches 88%.

Description

TECHNICAL FIELD

[0001] The present application relates to an aluminum alloy flat ingot for aviation and a preparation method thereof. BACKGROUND

[0002] The Al-Fe-Mn aluminum alloy flat ingot for aviation has the strength close to that of high-quality steel, good plasticity, and can be processed into various profiles, and has good electrical conductivity, thermal conductivity and corrosion resistance, and is widely used in industry. However, the alloy has a high Fe content, and shows a great crack tendency during casting, and the process parameters of melting and casting are extremely narrow, and cracks often occur during casting, and the purity of the melt is difficult to control, and the flaw detection passing rate is also low, and the finished product rate of the ingot is only 70%. SUMMARY

[0003] The present application relates to an aluminum alloy flat ingot for aviation and a preparation method thereof.

[0004] The aluminum alloy flat ingot for aviation of the present application is composed of, by mass percentage, 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.

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

[0006] I. aluminum ingot, Al-Fe intermediate alloy and Al-Mn intermediate alloy are weighed as smelting raw materials according to the following mass percentage: 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;

[0007] II. The smelting raw materials weighed in step I are melted, and the smelting raw materials are added in the following order: aluminum ingot is added first, then Al-Fe intermediate alloy and Al-Mn intermediate alloy are added, and stirring is performed at a temperature of 700 to 750°C for 15 to 25 minutes, and the chemical composition is analyzed by sampling, and after the chemical composition is qualified, the alloy melt is obtained by covering with flux;

[0008] III. The alloy melt obtained in step II is introduced into a static furnace at a temperature of 700 to 750°C, argon is introduced for 30 minutes for refining, and then static treatment is performed for 25 to 35 minutes to obtain a refined alloy melt, the refined alloy melt is first flowed into an online degassing device, then flowed into a filtering device, and then flowed through a flow disc at a casting speed of 50 to 60 mm / min, a temperature in front of a baffle of 690 to 710°C, and a cooling water flow rate of 130 to 170 m3 / min to obtain the aluminum alloy flat ingot for aviation.3 Under the condition of the melt injection crystallizer with the liquid level height of 75-95mm and the on-line seeding of Al-5Ti-0.2B wire, the semi-continuous casting is carried out to obtain the aluminum alloy flat ingot for aviation.

[0009] The present application has the following advantages:

[0010] The present application can effectively remove H2 in the melt by flowing into the on-line degassing device, and can effectively remove slag by flowing into the filtering device; the tendency of the ingot cold shut is reduced by increasing the initial casting speed and the liquid level, and the tendency of the initial aluminum leakage is reduced by increasing the initial water flow; the yield of the ingot product is improved to 88% according to the above method, and the problem of low yield of the ingot product prepared by the existing method is solved. DETAILED DESCRIPTION

[0011] The technical solution of the present application is not limited to the following specific embodiments, and also includes any combination between the specific embodiments.

[0012] Specific embodiment one: the aluminum alloy flat ingot for aviation in the present embodiment is composed of 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 of aluminum.

[0013] A small amount of Ti and B is added to significantly refine the alloy grain and reduce the crack tendency of the alloy.

[0014] Si, Cu, Mg and Zn are impurity elements, and the lower the content is, the better.

[0015] The smelting raw material in the present embodiment is aluminum ingot, Al-Fe intermediate alloy and Al-Mn intermediate alloy.

[0016] Specific embodiment two: the difference between the present embodiment and specific embodiment one is that the aluminum alloy flat ingot for aviation is composed of less than 0.30% of Si, 1.3% of Fe, less than 0.20% of Cu, 0.5% of Mn, less than 0.1% of Mg, less than 0.10% of Zn, less than 0.10% of Ti and the balance of aluminum. The other steps and parameters are the same as those in specific embodiment one.

[0017] Specific embodiment three: the preparation method of the aluminum alloy flat ingot for aviation in the present embodiment is completed according to the following steps:

[0018] I. According to the mass percentage 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 of aluminum, take aluminum ingot, Al-Fe intermediate alloy, Al-Mn intermediate alloy as smelting raw materials;

[0019] II. The smelting raw materials of step I are melted, and the addition sequence of the smelting raw materials is: first, aluminum ingot is added, then Al-Fe intermediate alloy and Al-Mn intermediate alloy are added, and the smelting raw materials are stirred for 15~25 min under the condition that the temperature is 700~750℃, and the chemical composition is analyzed by sampling, and after the chemical composition is qualified, the alloy melt is obtained by covering the flux;

[0020] III. The alloy melt obtained in step II is introduced into a static furnace at a temperature of 700~750℃, argon is introduced for 30 min, and then the alloy melt is obtained after static for 25~35 min, the refined alloy melt is first flowed into an online degassing device, then flowed into a filtering device, and then flowed through a flow disc under the condition that the casting speed is 50~60 mm / min, the temperature in front of the baffle is 690~710℃, the cooling water flow is 130~170 m 3 / h, the crystallizer liquid level height is 75~95 mm, and the melt is injected into the crystallizer under the condition that the Al-5Ti-0.2B wire is seeded online, and the semi-continuous casting of the aviation aluminum alloy flat ingot is carried out.

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

[0022] In step II of the embodiment, the Al-Fe intermediate alloy and the Al-Mn intermediate alloy are added after the melt is melted and reaches 720℃; the stirring of the melt in this step is stirring for 20 min under the condition that the temperature is 730℃, and the stirring is carried out by electromagnetic stirring.

[0023] Specific embodiment four: the difference between the embodiment and the specific embodiment three is that the purity of the aluminum ingot in step I is 99.7%. The other steps and parameters are the same as those in the specific embodiment three.

[0024] Specific embodiment five: the difference between the embodiment and the specific embodiment four is that the content of Fe in the Al-Fe intermediate alloy in step I is 10%, and the rest is Al; the content of Mn in the Al-Mn intermediate alloy is 10%, and the rest is Al. The other steps and parameters are the same as those in the specific embodiment three.

[0025] Sixth embodiment: The embodiment is different from the third embodiment in that: in step one, the aluminum ingot, Al-Fe intermediate alloy, and Al-Mn intermediate alloy are weighed as smelting raw materials according to the mass percentage of less than 0.30% of Si, 1.3% of Fe, less than 0.20% of Cu, 0.5% of Mn, less than 0.1% of Mg, less than 0.10% of Zn, less than 0.10% of Ti, and the balance of aluminum. The other steps and parameters are the same as those in the third embodiment.

[0026] Seventh embodiment: The embodiment is different from the third embodiment in that: the smelting melt is stirred by electromagnetic stirring. The other steps and parameters are the same as those in the third embodiment.

[0027] Eighth embodiment: The embodiment is different from the third embodiment in that: stirring is performed by a slag skimming car. The other steps and parameters are the same as those in the third embodiment.

[0028] Ninth embodiment: The embodiment is different from the third embodiment in that: in step two, stirring is performed at 730°C for 20 min. The other steps and parameters are the same as those in the third embodiment.

[0029] Tenth embodiment: The embodiment is different from the third embodiment in that: in step two, the flux is composed of 40% of KCl, 45% of MgCl2, 8% of BaCl2, and 7% of NaCl+CaCl2 by mass percentage, and the addition amount is 2 kg / t of the melt. The other steps and parameters are the same as those in the third embodiment.

[0030] Eleventh embodiment: The embodiment is different from the third embodiment in that: in step three, the composition of the argon gas is 99.99% of argon. The other steps and parameters are the same as those in the third embodiment.

[0031] Twelfth embodiment: The embodiment is different from the third embodiment in that: in step three, the rate of the argon gas is 0.20-0.25 m 3 / min. The other steps and parameters are the same as those in the third embodiment.

[0032] Thirteenth embodiment: The embodiment is different from the third embodiment in that: in step three, the melt is first flowed into an online degassing device during casting, and the gas purity in the degassing device is 99.99% of argon. The other steps and parameters are the same as those in the third embodiment.

[0033] Fourteenth embodiment: The embodiment is different from the third embodiment in that: in step three, the precision of the ceramic sheet in the filtering device is 30 mesh+50 mesh. The other steps and parameters are the same as those in the third embodiment.

[0034] Specific embodiment fifteen: this embodiment is different from the specific embodiment three in that: in step three, semi-continuous casting is carried out under the conditions that the casting speed is 55 mm / min, the casting temperature is 705℃, the casting cooling water flow is 150 m 3 / h, the crystallizer liquid level height is 90 mm. The other steps and parameters are the same as those in the specific embodiment three.

[0035] Specific embodiment sixteen: this embodiment is different from the specific embodiment three in that: in step three, the Ti content in the Al-5Ti-0.2B wire 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 the specific embodiment three.

[0036] Specific embodiment seventeen: this embodiment is different from the specific embodiment three in that: in step three, the shape of the melt injected into the crystallizer is a rectangle of 420 mm x 1320 mm. The other steps and parameters are the same as those in the specific embodiment three.

[0037] Specific embodiment eighteen: this embodiment is different from the specific embodiment three in that: in step three, the dummy head shape of the melt injected into the crystallizer is a flat arc of 420 mm x 1320 mm. The other steps and parameters are the same as those in the specific embodiment three.

[0038] Specific embodiment nineteen: this embodiment is different from the specific embodiment three in that: in step three, the size of the semi-continuous casting aluminum alloy flat ingot for aviation is 420 mm x 1320 mm x (3000 mm-7000 mm mm). The other steps and parameters are the same as those in the specific embodiment three.

[0039] The beneficial effects of the present application are verified by the following examples:

[0040] Example one: the manufacturing method of the industrial aluminum alloy flat ingot is realized by the following steps:

[0041] I. 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, aluminum ingot, Al-Fe intermediate alloy, Al-Mn intermediate alloy are taken as the smelting raw materials;

[0042] II. The smelting raw materials taken in step I are melted, and the addition sequence of the smelting raw materials is: first, the aluminum ingot is added, then the Al-Fe intermediate alloy and the Al-Mn intermediate alloy are added, and the stirring is carried out for 20 min under the condition that the temperature is 710℃, the chemical composition is analyzed by sampling, and after the chemical composition is qualified, the alloy melt is obtained after covering with flux;

[0043] III. The alloy melt obtained in step II is introduced into a static furnace at a temperature of 740°C, argon is introduced for 30 minutes for refining, and then the alloy melt is left to stand for 30 minutes to obtain a refined alloy melt. The refined alloy melt is first introduced into an on-line degassing device, then into a filtering device, and then into a crystallizer through a flow disc at a casting speed of 55 mm / min, a temperature in front of the baffle of 705°C, a cooling water flow rate of 150 m 3 / h, a crystallizer liquid level of 90 mm, and under the condition of on-line seeding of Al-5Ti-0.2B wire, the melt is injected into the crystallizer to perform semi-continuous casting to obtain the aluminum alloy flat ingot for aviation.

[0044] The aluminum alloy flat ingot for aviation obtained in this embodiment I is qualified in terms of chemical composition, has no cracks or slag inclusions on the surface, and has a yield rate of 89%.

[0045] Embodiment II: The method for manufacturing the aluminum alloy hollow ingot for the fuselage of an aircraft is implemented according to the following steps:

[0046] I. Al ingot, Al-Fe intermediate alloy, and Al-Mn intermediate alloy are weighed as smelting raw materials according to the following mass percentages: 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] II. The smelting raw materials weighed in step I are melted, the smelting raw materials are added in the following order: the Al ingot is added first, then the Al-Fe intermediate alloy and the Al-Mn intermediate alloy are added, and the smelting raw materials are stirred for 25 minutes at a temperature of 730°C. The chemical composition is analyzed by sampling, and the alloy melt is obtained after the chemical composition is qualified and the flux is covered.

[0048] III. The alloy melt obtained in step II is introduced into a static furnace at a temperature of 745°C, argon is introduced for 30 minutes for refining, and then the alloy melt is left to stand for 30 minutes to obtain a refined alloy melt. The refined alloy melt is first introduced into an on-line degassing device, then into a filtering device, and then into a crystallizer through a flow disc at a casting speed of 60 mm / min, a temperature in front of the baffle of 710°C, a cooling water flow rate of 160 m 3 / h, a crystallizer liquid level of 95 mm, and under the condition of on-line seeding of Al-5Ti-0.2B wire, the melt is injected into the crystallizer to perform semi-continuous casting to obtain the aluminum alloy flat ingot for aviation.

[0049] The aluminum alloy flat ingot for aviation obtained in this embodiment II is qualified in terms of chemical composition, has no cracks or slag inclusions on the surface, and has a yield rate of 83%.

Claims

1. A method for preparing aerospace-grade aluminum alloy flat casting ingots, characterized in that... The preparation method of aluminum alloy flat casting ingots for aviation is completed according to the following steps: I. Weigh out aluminum ingots, Al-Fe master alloys, and Al-Mn master alloys as smelting raw materials, based on the following mass percentages: Si < 0.30%, Fe: 1.2%~1.6%, Cu < 0.20%, Mn: 0.2%~0.6%, Mg < 0.10%, Zn < 0.10%, Ti < 0.10%, and the balance being aluminum. The Al-Fe master alloy contains 10% Fe, with the remainder being Al; the Al-Mn master alloy contains 10% Mn, with the remainder being Al.

2. Melt the smelting raw materials weighed in step 1. The order of adding the smelting raw materials is as follows: first add aluminum ingots, then add Al-Fe master alloy and Al-Mn master alloy. Stir for 15-25 minutes at a temperature of 700-750℃. Take samples to analyze the chemical composition. After the chemical composition is qualified, cover with flux to obtain alloy melt. The flux is composed of 40% KCl, 45% MgCl2, 8% BaCl2, and 7% NaCl+CaCl2 by mass percentage, and its addition amount is 2 kg / ton of melt.

3. The alloy melt obtained in step 2 is introduced into a holding furnace at a temperature of 700~750℃, refined by argon gas for 30 minutes, and then held for 25~35 minutes to obtain a refined alloy melt. The refined alloy melt is first flowed into an online degassing device, then into a filtration device, and then through a flow plate at a casting speed of 50~60mm / min, a temperature before the baffle of 690~710℃, and a cooling water flow rate of 130~170m³ / min. 3 The melt is injected into the crystallizer under the conditions of 75~95mm liquid level in the crystallizer and online seeding of Al-5Ti-0.2B wire to obtain flat ingots of aluminum alloy for aviation by semi-continuous casting; 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 420mm / min per ingot.

2. The method for preparing an aerospace aluminum alloy flat casting ingot according to claim 1, characterized in that... In step two, stir at 730℃ for 20 minutes.

3. The method for preparing an aerospace aluminum alloy flat casting ingot according to claim 1, characterized in that... In step three, the rate at which argon gas is introduced is 0.20~0.25m. 3 / min.

4. The method for preparing an aerospace aluminum alloy flat casting ingot according to claim 1, characterized in that... In step three, the ceramic discs in the filter device have a mesh size of 30 mesh + 50 mesh.

5. The method for preparing an aerospace aluminum alloy flat casting ingot according to claim 1, characterized in that... In step three, the casting speed is 55 mm / min, the temperature in front of the baffle is 705℃, and the cooling water flow rate is 150 m³ / min. 3 The melt is injected into the crystallizer under the conditions of / h, crystallizer liquid level height of 90mm, and online seeding of Al-5Ti-0.2B wire.