Preparation method of 2A14 aluminum alloy square cast ingot

Abstract

The invention discloses a preparation method of a 2A14 aluminum alloy square cast ingot, and belongs to the technical field of aluminum alloys. The preparation method comprises the following steps: (1) mixing and smelting a primary aluminum ingot, an AlCu40 intermediate alloy, an AlMn15 intermediate alloy, an AlSi20 intermediate alloy and an Mg ingot to obtain a melt; (2) sequentially carrying out in-furnace purification and on-line purification on the melt to obtain a purified melt; (3) the purified melt is subjected to grain refinement, an AlTi5B1 wire is adopted for grain refinement, and the adding amount is 1.8-2.2 kg / t; (4) the melt obtained after grain refinement is cast, the casting speed is 45-65 mm / min, and the water flow is 40-70 m < 3 > / h; and (5) carrying out homogenization heat treatment on the casting product to obtain the 2A14 aluminum alloy square cast ingot. The method and cast ingot components are optimized together, so that the 2A14 aluminum alloy finished plate is subjected to chemical milling to obtain a latticed product with flat surface and basically straight grid ribs.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum alloys, and in particular to a method for preparing a 2A14 aluminum alloy square ingot. Background Art

[0002] Chemical milling (Chemical milling) is a processing technology that uses chemical solutions to corrode and dissolve the metal surface. It removes the surface metal by immersing the metal parts in a specific chemical solution and uses the corrosion of the solution to obtain the desired shape and size. This processing method does not require mechanical cutting force, so it is particularly suitable for removing a large amount of material, processing complex shapes and thin-walled structural parts. Chemical milling is widely used in the aerospace industry, such as the processing of large thin-walled parts such as aircraft wing leading edges, fuselage panels, and variable thickness skins. These parts are usually made of thick plates and are processed into thin-walled parts with complex curved surfaces and pits, grids, and ribs milled on the surface through chemical milling.

[0003] 2A14 aluminum alloy is a kind of hard aluminum alloy material. Its main chemical components are zinc, iron, magnesium, aluminum, etc. It has good machinability, resistivity, spot welding and seam welding performance. In addition, it has excellent mechanical properties, corrosion resistance and machinability. Therefore, it is widely used in aerospace, national defense, sports equipment, automobiles and rail transportation.

[0004] However, in the preparation process of 2A14 alloy square ingot, since the 2A14 alloy aluminum liquid contains Mn, Cu alloy elements and impurity element Fe, Al6 (CuFeMn) compound phase is formed through eutectic reaction during solidification. This compound phase exists at the grain boundary of adjacent grains in the ingot microstructure, and will be transformed into Al (CuMnFe) Si phase after homogenization process. However, the electrode potential of Al (CuMnFe) Si phase is significantly different from that of the base metal, resulting in the formation of galvanic effect and non-uniform corrosion in the corrosive medium. If there is an aggregated compound phase (Al (CuMnFe) Si phase) in the prepared square ingot structure, it will be left in the plate, showing a local string aggregation phenomenon of Al (CuMnFe) Si phase along the rolling deformation direction. In the process of plate milling, pits, grid rib bending and uneven milling defects such as uneven milling will be formed due to the aggregation of compounds, which cannot meet the milling requirements.

[0005] Therefore, it is of great significance to study and develop a new method for preparing 2A14 aluminum alloy square ingots, so that the content of Al(CuMnFe)Si phase is reduced or the size is reduced to alleviate the string aggregation phenomenon in the plate, thereby improving the milling quality of the plate. Summary of the invention

[0006] In view of this, the technical problem to be solved by the present invention is to provide a method for preparing 2A14 aluminum alloy square ingots. The 2A14 aluminum alloy square ingots prepared by the preparation method can obtain a grid-shaped product with a flat surface and substantially straight grid ribs after chemical milling of the 2A14 aluminum alloy sheet.

[0007] In order to achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] The present invention provides a method for preparing a 2A14 aluminum alloy square ingot, comprising the following steps:

[0009] (1) mixing and smelting the original aluminum ingot, AlCu40, AlMn15, AlSi20 master alloy, and Mg ingot to obtain a melt;

[0010] (2) sequentially performing in-furnace purification and online purification on the melt to obtain a purified melt;

[0011] (3) grain refining the purified melt, wherein AlTi5B1 wire is used for grain refining, and the addition amount is 1.8-2.2 kg / t;

[0012] (4) Casting the melt after grain refinement, wherein the casting speed is 45 to 65 mm / min and the water flow rate is 40 to 70 m / min. 3 / h / root;

[0013] (5) performing homogenization heat treatment on the casting product to obtain a 2A14 aluminum alloy square ingot;

[0014] The 2A14 aluminum alloy square ingot comprises the following components:

[0015] Si 0.70%~1.10%, Fe≤0.15%, Cu 3.95%~4.20%, Mn 0.4%~1.0%, Mg0.45%~0.75%, Ti≤0.05%, Ni<0.10, Zn≤0.30, and the balance is Al.

[0016] The present invention optimizes the preparation method and the composition of the 2A14 aluminum alloy square ingot together, so that the prepared 2A14 aluminum alloy square ingot can obtain a grid-shaped product with a flat surface and substantially straight grid ribs after chemical milling.

[0017] Through the above-mentioned joint optimization, the contents of Cu, Mn and Fe in the prepared 2A14 aluminum alloy square ingot are reduced, thereby reducing the formation of the compound phase (Al(CuMnFe)Si phase).

[0018] In the 2A14 aluminum alloy square ingot, preferably, the Si content is 0.80% to 1.00%, and more preferably 0.88%, 0.85% or 0.87%.

[0019] Preferably, the Fe content is 0.05% to 0.08%; more preferably 0.07% or 0.06%.

[0020] Preferably, the Cu content is 3.90% to 4.00%; more preferably 3.98%, 3.92% or 4.00%.

[0021] Preferably, the Mn content is 0.60% to 0.80%, and more preferably 0.70% or 0.68%.

[0022] Preferably, the Mg content is 0.50% to 0.60%; more preferably 0.60%, 0.59% or 0.57%.

[0023] Preferably, the Ti content is 0.02%;

[0024] Preferably, the Ni content is 0.01%;

[0025] Preferably, the Zn content is 0.02% to 0.04%; more preferably 0.04% or 0.02%.

[0026] Further preferably, the 2A14 aluminum alloy square ingot comprises the following components:

[0027] Si 0.88%, Fe 0.07%, Cu 3.98%, Mn 0.70%, Mg 0.60%, Ni 0.01%, Zn 0.04%, Ti 0.02%, and the balance is Al.

[0028] Alternatively, further preferably, the 2A14 aluminum alloy square ingot comprises the following components:

[0029] Si 0.85%, Fe 0.06%, Cu 3.92%, Mn 0.68%, Mg 0.59%, Ni 0.01%, Zn 0.02%, Ti 0.02%, and the balance is Al.

[0030] Alternatively, further preferably, the 2A14 aluminum alloy square ingot comprises the following components:

[0031] Si 0.87%, Fe 0.06%, Cu 4.00%, Mn 0.70%, Mg 0.57%, Ni 0.01%, Zn 0.02%, Ti 0.02%, and the balance is Al.

[0032] Preferably, in the step (4) of casting, the aluminum liquid temperature at the end of the flow plate is 695-720°C and the cooling water temperature is 18-30°C.

[0033] Preferably, the temperature of the homogenization heat treatment in step (5) is 495-505° C. and the temperature is kept at 24-30 hours.

[0034] Preferably, in the present invention, the smelting temperature in step (1) is 720°C to 760°C.

[0035] Preferably, the in-furnace purification in step (2) is selected from one or more of artificial refining, HD2000 refining, IRMA refining, and air-permeable brick refining;

[0036] Preferably, the online purification in step (2) is selected from two-stage dual-rotor rotary degassing and two-stage filtration.

[0037] The preparation method of the present invention makes the compound phase in the 2A14 aluminum alloy square ingot small in size, dispersed in distribution, and no obvious string-like compound is formed.

[0038] The string-like shape of the string-like compound refers to the shape characteristics of a series of compounds after aggregation. Specifically, the string-like compound is formed by the large compound phase (Al(CuMnFe)Si phase) in the ingot structure being crushed and deformed along the rolling direction during the deformation process.

[0039] Compared with the prior art, the method for preparing 2A14 aluminum alloy square ingot provided by the present invention comprises the following steps: (1) mixing and smelting original aluminum ingots, AlCu40, AlMn15, AlSi20 master alloy, and Mg ingots to obtain a melt; (2) sequentially performing in-furnace purification and online purification on the melt to obtain a purified melt; (3) performing grain refinement on the purified melt, wherein the grain refinement adopts AlTi5B1 wire with an addition amount of 1.8 to 2.2 kg / t; (4) casting the melt after grain refinement, wherein the casting speed is 45 to 65 mm / min, and the water flow rate is 40 to 70 m / min. 3 / h / root; (5) subjecting the above casting product to homogenization heat treatment to obtain 2A14 aluminum alloy square ingot; the 2A14 aluminum alloy square ingot comprises the following components: Si 0.70%-1.10%, Fe≤0.15%, Cu 3.95%-4.20%, Mn 0.4%-1.0%, Mg0.45%-0.75%, Ti≤0.05%, Ni<0.10, Zn≤0.30, and the balance is Al. The preparation method and the optimization of the composition of the 2A14 aluminum alloy square ingot enable the prepared 2A14 aluminum alloy finished plate to obtain a grid-shaped product with a flat surface and substantially straight grid ribs after chemical milling, which can better meet industrial needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1The microstructure diagrams of the 2A14 aluminum alloy square ingot and its plate prepared in Example 1, wherein Figure a is a microstructure diagram of the ingot magnified 50 times under an electron microscope, Figure b is a microstructure diagram of the ingot magnified 200 times, and Figure c is a microstructure diagram of the plate magnified 50 times;

[0041] Figure 2 These are the microstructure images of the 2A14 aluminum alloy square ingot and its plate prepared in Comparative Example 1, wherein Figure a is the microstructure image of the ingot magnified 50 times under an electron microscope, Figure b is the microstructure image of the ingot magnified 200 times, and Figure c is the microstructure image of the plate magnified 50 times. DETAILED DESCRIPTION

[0042] In order to further illustrate the present invention, the preparation method of the 2A14 aluminum alloy square ingot provided by the present invention is described in detail below in conjunction with embodiments.

[0043] Example 1

[0044] Preparation of 2A14 aluminum alloy square ingot

[0045] The preparation process includes: alloy batching, alloy smelting to obtain a melt, in-furnace purification of the melt, online purification of the melt, grain refinement of the purified melt, casting and heat treatment of the grain-refined melt, and preparing a 2A14 aluminum alloy square ingot.

[0046] Alloy ingredients: original aluminum ingots, AlCu40, AlMn15, AlSi20 master alloys, and Mg ingots are used as raw materials, and the Cu element is 3.95-4.20%, the Mn element is 0.40-1.0%, the Mn element is 0.40-1.0%, and the Mg element is 0.45-0.75%. In this embodiment, the original aluminum ingot preferably has an Al content of 99.90 or above to control the Fe content; AlCu40, AlMn15, and AlSi20 are preferably master alloys with fine sizes and uniform distribution of compounds such as Al2Cu, Al6Mn, and coarse-crystalline silicon in the microstructure.

[0047] Alloy smelting: In this embodiment, the original aluminum ingot, AlCu40, AlMn15, and AlSi20 are added into the smelting furnace. When they are completely melted into alloy aluminum liquid, when the temperature rises to 720℃~745℃, the Mg ingot is added by pressing to reduce burning loss. The reaction time is not less than 15 minutes. The temperature is controlled at 720℃~760℃ during the smelting process.

[0048] Purification in the furnace: artificial refining, HD2000 refining, IRMA refining, and air brick refining can be used in the furnace. In this embodiment, air brick refining is preferred. The air brick is installed at the bottom of the static furnace. The refining gas is Ar gas, and the gas flow rate is 8-20 L / min / block, preferably 15-18 L / min / block.

[0049] Grain refinement: In this embodiment, AlTi5B1 wire is used for online grain refinement, and the amount of grain refiner added is 2.2 kg / t, and the grain refiner is added before the double rotor rotation degassing.

[0050] Online purification: In this embodiment, the online degassing preferably adopts two-stage dual-rotor rotary degassing; the online filtration adopts two-stage filtration, the first stage adopts a ceramic filter plate with a precision of 40PPi, and the second stage adopts a ceramic filter plate with a precision of 50PPi.

[0051] Casting process: Ingot thickness is 400 mm, casting speed in this embodiment is 59-61 mm / min; water flow rate is 65-69 m 3 / h / root, water temperature is 28℃; the temperature at the end of the flow plate is 695℃~715℃. With this parameter, the ingots are fully formed.

[0052] Heat equalization process: The heat equalization system of this embodiment adopts single-stage heat equalization, and the heat equalization and insulation temperature is 495-500 (±5) ° C, preferably 500±5 ° C, and more preferably 500±3 ° C; the insulation time is 15-25h, preferably 24h.

[0053] The composition of the 2A14 aluminum alloy square ingot obtained by the above preparation method is: Si 0.88%, Fe 0.07%, Cu 3.98%, Mn 0.70%, Mg 0.60%, Ni 0.01%, Zn 0.04%, Ti 0.02%, and the balance is Al.

[0054] Example 2

[0055] Preparation of 2A14 aluminum alloy square ingot

[0056] Grain refinement: In this embodiment, AlTi5B1 wire is used for online grain refinement, and the amount of grain refiner added is 1.9 kg / t.

[0057] Casting process: The casting thickness is 400 mm, the casting speed is preferably 52-54 mm / min, and the water flow rate in this embodiment is 55-58 m 3 / h / root, water temperature is 21℃; the temperature at the end of the flow plate is 700℃~710℃. With this parameter, the ingots are fully formed.

[0058] The rest of the preparation process is the same as in Example 1.

[0059] The composition of the 2A14 aluminum alloy square ingot obtained by the above preparation method is: Si 0.85%, Fe 0.06%, Cu 3.92%, Mn 0.68%, Mg 0.59%, Ni 0.01%, Zn 0.02%, Ti 0.02%, and the balance is Al.

[0060] Example 3

[0061] Casting process: The casting thickness is 400mm, the casting speed of this embodiment is 46-48mm / min, and the water flow rate of this embodiment is 52-55m 3 / h / root. With this parameter, all the ingots are formed.

[0062] The rest of the preparation process is the same as in Example 1.

[0063] The composition of the 2A14 aluminum alloy square ingot obtained by the above preparation method is: Si 0.87%, Fe 0.06%, Cu 4.00%, Mn 0.70%, Mg 0.57%, Ni 0.01%, Zn 0.02%, Ti 0.02%, and the balance is Al.

[0064] Comparative Example 1

[0065] Grain refinement: In this embodiment, AlTi5B1 wire is used for online refinement, and the amount of refiner added is 1.8-2.2 kg / t

[0066] Casting process: The ingot thickness is 400mm, the casting speed of this comparative example is 55mm / min, and the water flow rate is 30m 3 / h / root. With this parameter, the ingot can be formed.

[0067] The rest of the preparation process is the same as in Example 1.

[0068] The composition of the 2A14 aluminum alloy square ingot obtained by the above preparation method is: Si 0.89%, Fe 0.17%, Cu 3.94%, Mn 0.78%, Mg 0.56%, Ni 0.01%, Zn 0.01%, Ti 0.02%, and the balance is Al.

[0069] Comparative Example 2

[0070] Grain refinement: In this embodiment, AlTi5B1 wire is used for online grain refinement, and the amount of grain refiner added is 1.2 kg / t.

[0071] Casting process: Ingot thickness is 400mm, casting speed is 35mm / min, water flow rate is 22m 3 / h / root. With this parameter, the ingot can be formed.

[0072] The rest of the preparation process is the same as in Example 1.

[0073] The composition of the 2A14 aluminum alloy square ingot obtained by the above preparation method is: Si 0.89%, Fe 0.08%, Cu 3.95%, Mn 0.72%, Mg 0.60%, Ni 0.01%, Zn 0.02%, Ti 0.02%, and the balance is Al.

[0074] The compound size of the 2A14 alloy ingot prepared in the above examples 1 to 3 is smaller and the distribution is more dispersed. Figure 1 Middle B picture and Figure 2 From the comparison of Figure b, it can be seen that the compound size in the 2A14 alloy ingot of Example 1 is finer than that of Comparative Example 1, and the compound distribution is more dispersed than that of Comparative Example 1.

[0075] like Figure 1 and Figure 2 From the comparison of Figure c, it can be seen that the 2A14 aluminum alloy square ingot prepared in Example 1 is subjected to rolling deformation to obtain a 2A14 aluminum alloy plate, and its plate structure has the advantages of fine compound phase size, dispersed distribution, and no obvious string-like compounds compared with the 2A14 aluminum alloy plate obtained after rolling deformation in Comparative Example 1. This indicates that there is no aggregated large-sized compound phase in the 2A14 aluminum alloy square ingot prepared in Example 1 (because the compound phase in the ingot structure prepared in Example 1 is small in size and does not aggregate at the junction to form a large compound phase), that is, the size of the compound phase it contains (Al(CuMnFe)Si phase) is smaller than that in Comparative Example 1.

[0076] The 2A14 aluminum alloy square ingots prepared in the above Examples 1 to 3 were rolled and deformed to obtain 2A14 aluminum alloy plates, and the obtained plates were subjected to chemical milling to test the improvement of the preparation method of the present invention on the 2A14 aluminum alloy plates.

[0077] The above-mentioned chemical milling uses 40% to 60% NaOH solution and 20% to 30% HNO3 solution for surface treatment for 60 to 120 minutes respectively, and then after operations such as brushing glue and engraving, 50 to 90g / LAl and 60 to 130g / LNaOH mixed solution is used for chemical milling to obtain a grid-like product with a smooth surface without local pits and basically straight grid ribs, which is qualified for chemical milling.

[0078] However, after the 2A14 aluminum alloy square ingots prepared in Comparative Examples 1 and 2 were rolled and deformed to obtain 2A14 aluminum alloy plates, due to the presence of string-like compounds in the plates (wherein string-like refers to the shape characteristics of a series of aggregated compounds. Specifically, the string-like compounds are formed by the crushing and deformation of large compound phases (Al(CuMnFe)Si phase) in the ingot structure along the rolling direction during the deformation process), after the above-mentioned chemical milling operation, local pits appeared on the surface of the plates, and the grid ribs were bent and not straight, which was unqualified for chemical milling.

[0079] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a 2A14 aluminum alloy square ingot, characterized in that: The following steps are involved: (1) mixing and smelting the original aluminum ingot, AlCu40, AlMn15, AlSi20 master alloy, and Mg ingot to obtain a melt; (2) sequentially performing in-furnace purification and online purification on the melt to obtain a purified melt; (3) grain refining the purified melt, wherein AlTi5B1 wire is used for grain refining, and the addition amount is 1.8-2.2 kg / t; (4) Casting the melt after grain refinement, wherein the casting speed is 45 to 65 mm / min and the water flow rate is 40 to 70 m / min. 3 / h / root; (5) performing homogenization heat treatment on the casting product to obtain a 2A14 aluminum alloy square ingot; The 2A14 aluminum alloy square ingot comprises the following components: Si 0.70%~1.10%, Fe≤0.15%, Cu 3.95%~4.20%, Mn 0.4%~1.0%, Mg0.45%~0.75%, Ti≤0.05%, Ni<0.10, Zn≤0.30, and the balance is Al.

2. The preparation method according to claim 1, characterized in that: During the casting in step (4), the aluminum liquid temperature at the end of the flow plate is 695-720°C, and the cooling water temperature is 18-30°C.

3. The preparation method according to claim 1, characterized in that: The temperature of the homogenization heat treatment in step (5) is 495-505° C. and the temperature is kept for 24-30 hours.

4. The preparation method according to claim 1, characterized in that: The smelting temperature in step (1) is 720°C to 760°C.

5. The preparation method according to claim 1, characterized in that: The in-furnace purification in step (2) is selected from one or more of manual refining, HD2000 refining, IRMA refining, and air-permeable brick refining; The online purification in step (2) is selected from two-stage dual-rotor rotary degassing and two-stage filtration.

Images