A large-size flat ingot of Al-Mg-Mn-Zr-Sc series deformed aluminum alloy with a Mg content of 4.4% and a manufacturing method thereof

Abstract

A large-size flat ingot of an Al-Mg-Mn-Zr-Sc series deformed aluminum alloy with a Mg content of 4.4% and a manufacturing method thereof, wherein the Mg content in the main elements of the ingot is as high as 4.4%, and the ingot is cast at high temperature. Manufacturing method: batching and smelting, smelting pure ingots, pure magnesium ingots, aluminum-manganese master alloys, aluminum-scandium master alloys, aluminum-zirconium master alloys, aluminum-titanium master alloys, and aluminum-beryllium master alloys to obtain a melt, adding a covering agent after heating, and then refining with Ar-Cl2 gas, and finally casting. Compared with the general Al-Mg-Mn-Zr-Sc series deformed aluminum alloy, the present invention greatly reduces the Mg element content and increases the thickness of the ingot, so that the tendency of pores, slag inclusions, and cracking to be generated during the production of the ingot increases, and the casting temperature is increased and the casting speed is reduced to improve the quality of the ingot. The present invention adopts the existing smelting and batching process and reduces the generation of ingot quality defects by improving the process during the casting process, and the ingot yield rate reaches 94%.

Description

Technical Field

[0001] The invention relates to a large-size flat ingot of aluminum alloy and a manufacturing method thereof. Background Art

[0002] Al-Mg-Mn-Zr-Sc series ultra-high strength aluminum alloys have the advantages of high specific strength, high fracture toughness, excellent corrosion resistance in extreme environments, strong fatigue resistance, etc., and are mostly used in the manufacturing of aerospace, space stations and other fields. With the continuous improvement of the performance index requirements of the final product and the continuous emergence of new products, the basic performance requirements for raw materials are also constantly increasing. In order to meet the requirements of improving the comprehensive performance of the alloy under large-scale conditions, the Mg content is reduced, but at present, large-scale flat ingots containing Sc with low Mg content are difficult to form, have strong slag inclusions, pores, and cracking tendencies, and the casting scrap rate is as high as more than 40%. Therefore, combined with the actual production situation, by adjusting the casting process parameters and casting tools, the pores, slag inclusions, and cracking tendencies in the casting process of large-scale flat ingots are reduced, and the surface quality of the ingots is improved. A semi-continuous casting method for large-scale flat ingots of Al-Mg-Mn-Zr-Sc series deformed aluminum alloy with a Mg content of 4.4% has been explored. Summary of the invention

[0003] In order to reduce the casting pores, slag inclusions and cracking tendency of a large-sized flat ingot of an Al-Mg-Mn-Zr-Sc series deformed aluminum alloy with a Mg content of 4.4% and improve its forming ability, the present invention provides a large-sized flat ingot of an Al-Mg-Mn-Zr-Sc series deformed aluminum alloy with a Mg content of 4.4% and a manufacturing method thereof.

[0004] The invention discloses a large-size flat ingot of an Al-Mg-Mn-Cr-Sc series deformed aluminum alloy with a Mg content of 4.4%. The mass percentages of the elements in the aluminum alloy flat ingot are: Mn: 0.15%-0.2%, Mg: 4.0%-4.6%, Ti: 0.05%-0.1%, Zr: 0.10%-0.13%, Sc: 0.1-0.3%, Si: <0.20%, Fe <0.25%, and the balance is Al.

[0005] Furthermore, the mass percentage of each element is as follows: Mn: 0.18%, Mg: 4.4%, Ti: 0.1%, Zr: 0.12%, Sc: 0.20%, Si﹤0.20%, Fe<0.25%, single impurity ≤0.05%, total impurity ≤0.15%, and the balance is Al.

[0006] The present invention discloses a method for manufacturing a large-sized flat ingot of an Al-Mg-Mn-Cr-Sc series deformed aluminum alloy having a Mg content of 4.4%. The method for manufacturing a large-sized flat ingot of an Al-Mg-Mn-Cr-Sc series deformed aluminum alloy having a Mg content of 4.4% is carried out in the following steps:

[0007] 1. Ingredients: According to the mass percentage of each element: Mn: 0.15% ~ 0.2%, Mg: 4.0% ~ 4.6%, Ti: 0.05% ~ 0.1%, Zr: 0.10% ~ 0.13%, Sc: 0.1% ~ 0.3%, Si: < 0.2%, Fe < 0.25%, the balance is Al. Weigh aluminum ingots, pure magnesium ingots, aluminum-titanium master alloys, aluminum-scandium master alloys, aluminum-zirconium master alloys, and aluminum-beryllium intermediate alloys.

[0008] 2. Melting:

[0009] A. First add the weighed smelting raw materials into pure aluminum ingots and melt them at a set temperature of 760℃~800℃;

[0010] B. After the metal in the furnace is completely melted, when the melt temperature reaches above 780°C, the aluminum-scandium master alloy, aluminum-zirconium master alloy, and aluminum-titanium master alloy are charged into the gas melting furnace for melting, and stirred once every half an hour above 780°C, for a total of three times. 20 minutes after the stirring is completed, pure magnesium ingots are added at a temperature not lower than 760°C, and aluminum-beryllium master alloy is added at 0.03% of the mass of the melt in the melting furnace. After fully stirring for 10 to 15 minutes, a sample for chemical composition analysis is taken. After the chemical composition is qualified, a covering agent is added at 0.4% to 0.6% of the mass of the melt in the melting furnace to obtain a melt;

[0011] C. The obtained alloy melt is introduced into a gas-fired heat preservation furnace at a temperature not lower than 800°C, and a high-purity Ar-Cl2 mixed gas is introduced into the melt in the melting furnace for refining and standing. The refined alloy melt obtained in the standing furnace first flows through an online degassing device, and then through a filtering device before casting.

[0012] 3. Casting: The melt is heated at a temperature of 760°C to 780°C and a water flow rate of 40m 3 / h~50m 3 / h, and the casting is carried out under the conditions of a speed of 42mm / min~48mm / min, and the melt is injected into the crystallizer under the condition of online seeding of Al-5Ti-B wire, and water-cooled semi-continuous casting is carried out to obtain an alloy ingot with a thickness of 520mm, a width of 1620mm, and a length of 5000mm~6000mm.

[0013] Furthermore, in step 1, the mass percentage of each element is: Mn: 0.18%, Mg: 4.4%, Ti: 0.1%, Zr: 0.12%, Sc: 0.20%, Si﹤0.20%, Fe<0.25%, single impurity ≤0.05%, total impurity ≤0.15%, and the balance is Al.

[0014] Furthermore, the covering agent described in step 2B is 2# flux.

[0015] Furthermore, the Ar-Cl2 gas described in step 2C is a high-purity argon-chlorine mixed gas with a chlorine content of 5%.

[0016] Furthermore, in step 3, the temperature is 780°C and the water flow rate is 42m 3 / h and a speed of 45mm / min, the aluminum alloy melt obtained in step 2 is cast into an alloy ingot with a thickness of 520mm, a width of 1620mm and a length of 5600mm.

[0017] The impurity elements in the large-size flat ingot of the Al-Mg-Mn-Zr-Sc series deformed aluminum alloy with a Mg content of 4.4% of the present invention are derived from the aluminum ingot; Si: <0.12%, Fe≤0.15%, a single impurity≤0.05%, and a total impurity≤0.15%. The impurities within this range have no effect on the performance of the aluminum alloy plate.

[0018] Compared with the general Al-Mg-Mn-Zr-Sc alloy, the large-sized flat ingot of the Al-Mg-Mn-Zr-Sc series deformed aluminum alloy with a Mg content of 4.4% of the present invention has a lower Mg element content in order to improve fatigue resistance. Due to the significant reduction of the Mg element, the melt viscosity increases and the fluidity decreases. The large-sized flat ingot is prone to slag inclusion, pores, and cracking defects. The melt fluidity is improved by increasing the casting melt temperature, refining with high-purity Ar-Cl2 mixed gas in the insulation furnace, treating the melt with an online melt degassing device, filtering at the end of the casting, etc., to improve the melt quality; adjusting the casting speed, strengthening the cooling and lubrication of the casting process, and improving the ingot pores, slag inclusions, and cracking defects. The 520*1620 large-sized flat ingot prepared by the present invention can be used for industrial production of ingots of thick aluminum plates. Due to its large size, the difficulty of solidification and molding of the ingot and the casting process are very different. It can meet the thick plates actually used in the aerospace field, and its practical performance far exceeds that of the small-sized alloy ingot. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Photograph of large-sized flat ingot of deformed aluminum alloy of the present invention;

[0020] Figure 2 The sampling diagram of the large-sized flat ingot of the deformed aluminum alloy and the Sc-containing high-Mg aluminum alloy flat ingot of the present invention; wherein 1-7 represent the sampling numbers. DETAILED DESCRIPTION

[0021] Specific implementation method 1: In this implementation method, the mass percentage of each element in the large-size flat ingot of Al-Mg-Mn-Zr-Sc deformed aluminum alloy with a Mg content of 4.4% is: Mn: 0.15%~0.2%, Mg: 4.0%~4.6%, Ti: 0.05%~0.1%, Sc: 0.1%~0.3%, Zr: 0.10%~0.13%, Si: <0.2%, Fe<0.25%, and the remainder is Al.

[0022] The impurity elements in this embodiment are derived from aluminum ingots; impurity Si: <0.12%, Fe≤0.15%, single impurity≤0.05%, total impurity≤0.15%, and impurities within this range have no effect on the performance of the aluminum alloy plate.

[0023] The large-sized flat ingot of Al-Mg-Mn-Zr-Sc deformed aluminum alloy with a Mg content of 4.4% in this embodiment has a higher melt viscosity and lower fluidity compared to the general Al-Mg-Mn-Zr-Sc alloy. The large-sized flat ingot is prone to slag inclusions, pores, and cracks. The fluidity of the melt is improved by increasing the casting melt temperature, refining with high-purity Ar-Cl2 mixed gas in an insulation furnace, treating the melt with an online melt degassing device, filtering at the end of casting, etc., to improve the melt quality, adjust the casting speed, strengthen the cooling and lubrication of the casting process, and improve the pores, slag inclusions, and cracks of the ingot.

[0024] Specific embodiment 2: This embodiment is different from the specific embodiment 1 in that the mass percentages of the elements in the large-size flat ingot of the Al-Mg-Mn-Zr-Sc series deformed aluminum alloy with a Mg content of 4.4% are as follows: Mn: 0.18%, Mg: 4.4%, Ti: 0.1%, Zr: 0.12%, Sc: 0.20%, Si < 0.20%, Fe < 0.25%, single impurity ≤ 0.05%, total impurity ≤ 0.15%, and the balance is Al. The rest is the same as the specific embodiment 1.

[0025] Specific implementation method three: The method for manufacturing a large-size flat ingot of an Al-Mg-Mn-Zr-Sc series deformed aluminum alloy with a Mg content of 4.4% in this implementation method is carried out in the following steps:

[0026] 1. Ingredients: According to the mass percentage of each element: Mn: 0.18%, Mg: 4.4%, Ti: 0.1%, Zr: 0.12%, Sc: 0.2%, Si: <0.2%, Fe <0.25%, and the balance is Al. Weigh aluminum ingots, pure magnesium ingots, aluminum-titanium master alloys, aluminum-scandium master alloys, aluminum-zirconium master alloys, and aluminum-beryllium alloys.

[0027] 3. Melting:

[0028] A. Add the weighed smelting raw materials into pure aluminum ingots first, and melt them at a set temperature of 760℃~800℃;

[0029] B. After the metal in the furnace is completely melted, when the melt temperature reaches above 780°C, the aluminum-scandium master alloy, aluminum-zirconium master alloy, and aluminum-titanium master alloy are charged into the gas melting furnace for melting, and stirred once every half an hour at above 780°C, for a total of three times. 20 minutes after the stirring is completed, pure magnesium ingots are added at a temperature not lower than 760°C, and aluminum-beryllium master alloy is added at 0.03% of the mass of the melt in the melting furnace. After fully stirring for 10 to 15 minutes, a sample for chemical composition analysis is taken. After the chemical composition is qualified, a covering agent is added at 0.4% to 0.6% of the mass of the melt in the melting furnace to obtain a melt;

[0030] C. The obtained alloy melt is introduced into a gas-fired heat preservation furnace at a temperature not lower than 800°C, and a high-purity Ar-Cl2 mixed gas is introduced into the melt in the melting furnace for refining and standing. The refined alloy melt obtained in the standing furnace first flows through an online degassing device, and then through a filtering device before casting.

[0031] 3. Casting: The melt is heated at a temperature of 760°C to 780°C and a water flow rate of 40m 3 / h~50m 3 / h, and the casting is carried out under the conditions of a speed of 42mm / min~48mm / min, and the melt is injected into the crystallizer under the condition of online seeding of Al-5Ti-B wire, and water-cooled semi-continuous casting is carried out to obtain an alloy ingot with a thickness of 520mm, a width of 1620mm, and a length of 5000mm~6000mm.

[0032] Compared with the general Al-Mg-Mn-Zr-Sc alloy, the large-sized flat ingot of the Al-Mg-Mn-Zr-Sc deformed aluminum alloy with a Mg content of 4.4% in this embodiment has a lower Mg content in order to improve fatigue resistance. Due to the significant reduction of the Mg element, the melt viscosity increases and the fluidity decreases. The large-sized flat ingot is prone to slag inclusion, pores, and cracking defects. The fluidity of the melt is improved by increasing the casting melt temperature, refining with high-purity Ar-Cl2 mixed gas in a heat-insulating furnace, treating the melt with an online melt degassing device, filtering at the end of casting, etc., to improve the melt quality, adjust the casting speed, strengthen the cooling and lubrication of the casting process, and improve the ingot pores, slag inclusions, and cracking defects.

[0033] Specific embodiment 4: This embodiment differs from specific embodiment 3 in that the covering agent in step 3B is flux No. 2, and the rest is the same as specific embodiment 3. The flux No. 2 in this embodiment is a mixed flux whose main components are KCl, MgCl2 and BaCl2.

[0034] Specific embodiment 5: This embodiment differs from specific embodiments 3 to 5 in that the Ar-Cl2 gas described in step C is a high-purity argon-chlorine mixed gas with a chlorine content of 5%. The rest is the same as specific embodiments 3 and 4.

[0035] Specific implementation method 6: This implementation method is different from specific implementation method 5 in that the refining time in step C is 30 minutes and the standing time is 30 minutes. The rest is the same as specific implementation method 5.

[0036] Specific embodiment 7: This embodiment is different from any one of specific embodiments 3 to 6 in that: in step 3, the aluminum alloy melt obtained in step 2 is cast into an alloy ingot with a thickness of 520 mm, a width of 1620 mm, and a length of 5600 mm under the conditions of a temperature of 780°C, a water flow of 42 m3 / h, and a speed of 45 mm / min. The rest is the same as specific embodiments 3 to 6.

[0037] Embodiment 1: In this embodiment, a large-sized flat ingot of Al-Mg-Mn-Zr-Sc series deformed aluminum alloy with a Mg content of 4.4% and a method for manufacturing the same are implemented by the following steps:

[0038] 1. According to the mass percentage: Mn: 0.18%, Mg: 4.4%, Ti: 0.1%, Zr: 0.12%, Sc: 0.2%, Si: <0.2%, Fe <0.25%, the balance is Al. Weigh aluminum ingots, pure magnesium ingots, aluminum-titanium master alloys, aluminum-scandium master alloys, aluminum-zirconium master alloys, and aluminum-beryllium master alloys;

[0039] 2. Weigh the weighed smelting raw materials in step 1 and first add pure aluminum ingots to melt them at a set temperature of 760°C to 800°C. When the melt temperature reaches above 780°C, charge the aluminum-scandium master alloy, aluminum-zirconium master alloy, and aluminum-titanium master alloy into a gas-fired melting furnace for melting, and stir once every half an hour at above 780°C, for a total of three times. 20 minutes after the stirring is completed, add pure magnesium ingots at a temperature not lower than 760°C, and add aluminum-beryllium master alloy at 0.03% of the mass of the melt in the melting furnace. After fully stirring for 10 to 15 minutes, take a sample for chemical composition analysis. After the chemical composition is qualified, add 2# solvent covering agent at 0.4% to 0.6% of the mass of the melt in the melting furnace to cover it to obtain a melt.

[0040] 3. The alloy melt obtained in step 2 is introduced into a gas-fired heat preservation furnace at a temperature not lower than 800°C, and a high-purity Ar-Cl2 mixed gas is introduced into the melt in the smelting furnace for refining for 30 minutes, and then allowed to stand for 30 minutes. The refined alloy melt obtained in the heat preservation furnace first flows through an online degassing device, and then through a filtering device, and then is heated at 780°C and a water flow rate of 42m 3 / h and speed 43mm / min to form an alloy ingot with a thickness of 520mm, a width of 1620mm and a length of 5600mm.

[0041] In the first embodiment, the Al-Mg-Mn-Zr-Sc series deformed aluminum alloy large-sized flat ingot with a Mg content of 4.4% is obtained. The surface has no tensile cracks and slag inclusion crack defects. After the bottom of the Al-Mg-Mn-Zr-Sc series deformed aluminum alloy large-sized flat ingot with a Mg content of 4.4% prepared in the first embodiment is cut off, a 20 mm thick test piece is cut, and half of the sample in the width direction is taken for low-power inspection and mechanical property testing. The position of the sample to be tested is as follows: Figure 2 As shown. A low-power inspection was conducted on No. 7, and there were no pores, slag inclusions, shrinkage cavities, or shrinkage defects inside the ingot. The mechanical properties of samples No. 1-6 were tested, and the mechanical properties results are shown in Table 1. The mechanical properties of the scandium-containing high-magnesium aluminum alloy flat ingots at the same position were compared, as shown in Table 2. The mechanical properties meet the user's requirements. Compared with the scandium-containing high-magnesium aluminum alloy flat ingots, the invention has the following advantages: the content of precious metals such as Mg and Sc is reduced, the mechanical properties of the ingots are equivalent to those of high-magnesium Sc-containing flat ingots, and the ingot cost is greatly reduced. Moreover, the ingot specifications of the present invention are 100 mm thicker than the high-magnesium scandium-containing ingots. During rolling, the rolling deformation of the ingots is increased, and the quality of the finished plate is better guaranteed. The yield rate of the ingots reaches 94%, which is fully qualified for large-scale industrial production.

[0042] Table 1 Performance test results of large-size flat ingots of Al-Mg-Mn-Zr-Sc deformed aluminum alloy with Mg content of 4.4%

[0043]

[0044]

[0045] Table 2 Performance test results of Sc-containing high-Mg aluminum alloy slab

[0046]

Claims

1. A large-size flat ingot of Al-Mg-Mn-Zr-Sc series deformed aluminum alloy with a Mg content of 4.4%, characterized by: The mass percentage of each element in the aluminum alloy flat ingot is: Mn: 0.18%, Mg: 4.4%, Ti: 0.1%, Zr: 0.12%, Sc: 0.20%, Si < 0.20%, Fe < 0.25%, single impurity ≤ 0.05%, total impurity ≤ 0.15%, and the balance is Al; The method for manufacturing a large-size flat ingot of an Al-Mg-Mn-Zr-Sc series deformed aluminum alloy with a Mg content of 4.4% is carried out in the following steps:

1. Ingredients: According to the mass percentage of each element: Mn: 0.18%, Mg: 4.4%, Ti: 0.1%, Zr: 0.12%, Sc: 0.20%, Si < 0.20%, Fe < 0.25%, single impurity ≤ 0.05%, total impurity ≤ 0.15%, the balance is Al; weigh aluminum ingots, pure magnesium ingots, aluminum-titanium master alloy, aluminum-scandium master alloy, aluminum-zirconium master alloy, aluminum-beryllium master alloy; 2. Melting: A. Add the weighed smelting raw materials into pure aluminum ingots and melt them at a set temperature of 760℃~800℃; B. After the metal in the furnace is completely melted, when the melt temperature reaches above 780℃, add the aluminum-scandium intermediate alloy and aluminum-zirconium intermediate alloy. Gold and aluminum-titanium master alloy are placed in a gas-fired melting furnace for melting, and stirred once every half an hour at a temperature above 780°C, for a total of three times. After 20 minutes of stirring, pure magnesium ingots are added at a temperature not lower than 760°C, and aluminum-beryllium master alloy is added at 0.03% of the mass of the melt in the melting furnace. After fully stirring for 10-15 minutes, a sample for chemical composition analysis is taken. After the chemical composition is qualified, a covering agent is added at 0.4%-0.6% of the mass of the melt in the melting furnace to obtain a melt; C. The obtained alloy melt is introduced into a gas-fired holding furnace at a temperature not lower than 800°C, and a High-purity Ar-Cl2 mixed gas is introduced for refining and standing; the refined alloy melt obtained in the standing furnace first flows through an online degassing device, and then passes through a filtering device before casting; The covering agent is 2# flux; 3. Casting: The melt is heated to 780°C and the water flow rate is 42m 3 / h and a speed of 45mm / min, and the melt is injected into the crystallizer under the condition of online seeding of Al-5Ti-B wire, and water-cooled semi-continuous casting is carried out to obtain alloy ingots with a thickness of 520mm, a width of 1620mm, and a length of 5000mm~6000mm.

2. The large-sized flat ingot of Al-Mg-Mn-Zr-Sc series deformed aluminum alloy with a Mg content of 4.4% according to claim 1, characterized in that: The Ar-Cl2 gas described in step 2C is a high-purity argon-chlorine mixed gas with a chlorine content of 5%.

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