Al-zn-mg-sc alloy and use

Abstract

The application discloses an Al-Zn-Mg-Sc alloy and application, and the wire material comprises the following components in percentage by mass: Zr content 0.15-0.25%, Sc content 0.25-0.35%, Ti content <=0.1%, Cu content <=0.1%, Zn content 4.0-5.5%, Mn content 0.2-0.5%, Mg content 2.0-4.0%, Cr content 0.1-0.3%, and Be content 0.0001-0.005%. The 3D printing wire material with the above components is used to print a sample, and the mechanical properties of the printed body are as follows: tensile strength >=340 MPa, yield strength >=230 MPa, elongation rate is 15%, and direction difference is <=5%; after T6 heat treatment, the mechanical properties are improved to: tensile strength >=500 MPa, yield strength >=450 MPa, elongation rate >=10%, and direction difference <=5%.

Description

TECHNICAL FIELD

[0001] The present application relates to aluminum alloy wires, in particular to an Al-Zn-Mg-Sc alloy and application. BACKGROUND

[0002] Al-Cu, Al-Si, Al-Mg and other aluminum alloy wires are successfully applied in the fields of aviation, aerospace, weapons, etc. by arc additive manufacturing into qualified products, showing the unique advantages of arc additive manufacturing technology in manufacturing aluminum alloy components in terms of high efficiency, low cost and manufacturing large structural parts.

[0003] Al-Zn-Mg aluminum alloy is an aluminum alloy with Zn and Mg as main elements, which belongs to heat treatable aluminum alloy, has good hot deformation performance, and has a wide quenching range. Under appropriate heat treatment conditions, it can obtain high strength and good weldability. At present, there are few studies on arc additive manufacturing of Al-Zn-Mg aluminum alloy wires, and there are few reports on successful application of products in industrial production.

[0004] Chinese patent No. CN111471905A discloses an Al-Zn-Mg-Sc aluminum alloy wire for 3D printing and a preparation method thereof. The tensile strength of the aluminum alloy wire 3D printed part is 470-520 MPa, the yield strength is 370-410 MPa, and the elongation is 9-12%. The metal raw material contains the following chemical elements with the mass percentage: Zn 6.5-8.3%, Mg 2.5-3%, Mn 0.3-0.8%, Zr 0.05-0.25%, Cu 0.3-0.8%, Sc 0.1-0.5%, Ti 0.03-0.06%, impurities ≤0.3%, and the balance is Al.

[0005] Chinese patent application No. CN116144993A discloses a 7-series aluminum alloy wire for arc additive manufacturing and a preparation method and application thereof. The horizontal tensile strength of the aluminum alloy wire part printed by cold metal transfer (CMT) is ≥620 MPa, the yield strength is ≥520 MPa, and the elongation is ≤6.2%. The aluminum alloy wire contains the following components and mass percentages: Zn 6.0-10.0%, Mg 1.5-2.8%, Cu 1.0-2.2, Zr 0.05-0.25%, Sc 0.1-0.45%, Ti 0.05-0.25%, Fe ≤0.15, Si ≤0.10%, and the balance is Al.

[0006] The aluminum alloy wires in the above two patents are difficult to obtain high-quality wires due to work hardening and precipitation strengthening during production and manufacturing. SUMMARY

[0007] The application aims to provide an Al-Zn-Mg-Sc alloy and application, which is suitable for printing high-strength and high-elongation industrial components.

[0008] In order to achieve the above-mentioned purpose, the technical scheme adopted by the application is:

[0009] An Al-Zn-Mg-Sc alloy, by mass percentage, comprises the following alloy elements: Zr content 0.15-0.25%, Sc content 0.225-0.375%, Ti content ≤0.1%, Cu content ≤0.1%, Zn content 4.0-5.5%, Mn content 0.2-0.6%, Mg content 2.0-4.0%, Cr content 0.1-0.3%, Be content 0.0001-0.005%, and the balance is Al.

[0010] The application reduces the content of Zn, increases the mass percentage of Mg, improves the strength, reduces the tendency of welding cracks, and improves the corrosion resistance of the alloy.

[0011] In the component design, a trace amount of Cu element is added to improve the stress corrosion resistance and tensile strength, but the weldability of the alloy is reduced, and the content of Cu is designed to be ≤0.1%.

[0012] In the component design, a trace amount of Ti element is added to refine the as-cast structure of the alloy during the printing process, improve the weldability of the alloy, and the content of Ti is designed to be ≤0.1%.

[0013] Preferably, an Al-Zn-Mg-Sc alloy, by mass percentage, comprises the following alloy elements: Zr content 0.15-0.25%, Sc content 0.25-0.35%, Ti content ≤0.1%, Cu content ≤0.1%, Zn content 4.0-5.5%, Mn content 0.2-0.5%, Mg content 2.2-4.0%, Cr content 0.1-0.3%, and Be content 0.0001-0.005%.

[0014] Further preferably, an Al-Zn-Mg-Sc alloy, by mass percentage, comprises the following alloy elements: Cu 0.08%, Zn 5.4%, Mn 0.43%, Mg 2.8%, Zr 0.23%, Sc 0.35%, Ti 0.03%, Si 0.05%, Fe 0.08%, Cr 0.21%, Be 0.0005%, and the balance is Al.

[0015] According to the embodiments of the application, the application can be further optimized, and the following is the technical scheme formed after optimization:

[0016] In one preferred embodiment, Fe is less than or equal to 0.1%, Si is less than or equal to 0.05%, and each of the individual impurity elements is less than or equal to 0.05%, and the total amount of the impurity elements is less than or equal to 0.15%.

[0017] In the component design of the present application, Fe is a harmful element that reduces the corrosion resistance and mechanical properties of the alloy, and easily forms coarse compounds with Mn and Al, so the content of Fe is strictly controlled to be less than or equal to 0.1%.

[0018] In the component design of the present application, Si is a harmful element that reduces the strength and bending performance of the alloy and increases the tendency of welding cracks, so the content of Si is strictly controlled to be less than or equal to 0.05%.

[0019] In one preferred embodiment, 7.5%≤w(Zn+Mg)≤9.5%, and w(Zn):w(Mg)≤2.5.

[0020] In one preferred embodiment, 7.5%≤w(Zn+Mg)≤9.5%, and w(Zn):w(Mg)≤2.5.

[0021] In one preferred embodiment, w(Mn):w(Cr)=2. Both of them can improve the stress corrosion resistance of the alloy and reduce the tendency of stress corrosion.

[0022] In one preferred embodiment, w(Sc):w(Zr)=1.5. It can refine the grain structure, improve the weldability and recrystallization end temperature of the aluminum alloy, and improve the elongation of the aluminum alloy.

[0023] w(Mn), w(Cr), w(Sc), and w(Zr) respectively represent the mass percentage of Mn, Cr, Sc, and Zr.

[0024] In one preferred embodiment, the content of H is less than or equal to 0.15 mL / 100g Al. In the component design of the present application, the content of H in the melt during the melting and casting process of the aluminum alloy is strictly controlled. H in the melt easily forms pores, pinholes, and porosity during the solidification process, and can also cause secondary pores, bubbles, etc. during subsequent processing, which is not conducive to drawing and printing. Therefore, the content of H is strictly controlled to be less than or equal to 0.15 mL / 100g Al, and the lower the better.

[0025] In one preferred embodiment, the content of H is less than or equal to 0.15 mL / 100g Al. In the component design of the present application, the content of H in the melt during the melting and casting process of the aluminum alloy is strictly controlled. H in the melt easily forms pores, pinholes, and porosity during the solidification process, and can also cause secondary pores, bubbles, etc. during subsequent processing, which is not conducive to drawing and printing. Therefore, the content of H is strictly controlled to be less than or equal to 0.15 mL / 100g Al, and the lower the better.

[0026] In one preferred embodiment, the content of H is less than or equal to 0.15 mL / 100g Al. In the component design of the present application, the content of H in the melt during the melting and casting process of the aluminum alloy is strictly controlled. H in the melt easily forms pores, pinholes, and porosity during the solidification process, and can also cause secondary pores, bubbles, etc. during subsequent processing, which is not conducive to drawing and printing. Therefore, the content of H is strictly controlled to be less than or equal to 0.15 mL / 100g Al, and the lower the better.

[0027] The application discloses application of the Al-Zn-Mg-Sc alloy in electric arc additive manufacturing.

[0028] In one preferred embodiment, the protective gas is argon with a purity of 99.999%.

[0029] The Chinese patent application with the publication number CN116144993A comprehensively analyzes the reasons for the difficulty in wire forming, and the reasons are as follows: in the electric arc additive manufacturing process, the higher the contents of Zn and Mg elements are, the more serious the burning loss is, and Zn is particularly sensitive to thermal cracking tendency, so that the mechanical performance indexes of the Z direction of the printed body are seriously low, the direction difference is very prominent, and the elongation is extremely low, so that the actual industrial application cannot be carried out.

[0030] In the Al-Zn-Mg-Sc aluminum alloy wire material for electric arc additive manufacturing, Cu, Zn and Mg are main strengthening elements. The Cu element mainly improves the strength of the aluminum alloy by forming S (Al2CuMg) phase and theta (Al2Cu) phase, and when the content of Cu is too high, the crack resistance of the aluminum alloy is reduced. When Zn and Mg exist together, η (MgZn2) and T (Al2Mg2Zn3) are formed, the solubility of the η phase and the T phase in the aluminum changes sharply with the change of temperature, and has a strong precipitation strengthening effect, the higher the contents of Zn and Mg are, the higher the strength and hardness are, but the plasticity, stress corrosion resistance and fracture toughness are reduced. Mn, Sc, Zr, Ti, Be and Cr are trace beneficial elements. Fe, Si and H are impurity elements.

[0031] Compared with the prior art, the beneficial effects of the application are as follows:

[0032] The application adopts Al, Zn and Mg as main materials, adds trace amounts of Cu, Mn, Sc, Zr, Ti, Be and Cr beneficial elements into the main materials, and strictly controls Fe, Si and H impurity elements. The 3D printing wire material with the above-mentioned composition is used to print a sample, and the mechanical properties of the printed body are as follows: the tensile strength is greater than or equal to 340 MPa, the yield strength is greater than or equal to 230 MPa, the elongation is 15%, and the direction difference is less than or equal to 5%; after T6 heat treatment, the mechanical properties are improved to: the tensile strength is greater than or equal to 500 MPa, the yield strength is greater than or equal to 450 MPa, the elongation is greater than or equal to 10%, and the direction difference is less than or equal to 5%.

[0033] The advantages of the material of the present application relative to the existing Al-Zn-Mg alloy wire material are that the content of Zn is low, the content of Mg is high, the content of trace elements is high, and the ratio is reasonable, which is more conducive to the printing process, and in particular, the content of Zn is a key element that restricts the elongation.

[0034] The Al-Zn-Mg-Sc wire material is printed by adopting the cold metal transition (CMT) arc additive manufacturing method, the anisotropy can be effectively eliminated by optimizing the printing process parameters, in particular, the arc printing, and the qualified components with high strength and high elongation can be obtained by means of the auxiliary heat treatment system. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 The aluminum alloy printed body prepared for example 1.

[0036] Figure 2 The aluminum alloy printed body prepared for example 2.

[0037] Figure 3 The metallographic structure diagram of the aluminum alloy printed body prepared for example 3 after T6.

[0038] Figure 4 The metallographic structure diagram of the aluminum alloy printed body prepared for example 4 after T6. DETAILED DESCRIPTION

[0039] The present application will be described in detail below in combination with examples. It should be noted that the examples in the present application and the features in the examples can be combined with each other without conflict.

[0040] Example 1: The chemical composition (mass percentage) of the designed Al-Zn-Mg-Sc aluminum alloy wire material is: Cu 0.08%, Zn 5.4%, Mn 0.43%, Mg 2.8%, Zr 0.23%, Sc 0.35%, Ti 0.03%, Si 0.05%, Fe 0.09%, Cr 0.21%, Be 0.0005%, and the rest is Al. The qualified wire material is prepared by the following production process of continuous casting-continuous extrusion-drawing into wire.

[0041] The specific process parameters are as follows:

[0042] (1) Aluminum liquid smelting: aluminum ingot, aluminum manganese alloy, aluminum titanium alloy, aluminum chromium alloy, aluminum copper alloy, aluminum zirconium alloy, aluminum scandium alloy are added into the intermediate frequency furnace for heating and melting, then zinc ingot, magnesium ingot and aluminum beryllium alloy are added for heating and melting, the temperature of the aluminum liquid is 740-750℃, mechanical stirring is carried out for 30min at a speed of 300r\min, the element composition is adjusted by pre-furnace analysis, and qualified aluminum liquid is obtained;

[0043] (2) Refining degassing: the aluminum liquid is transferred into a refining furnace for refining degassing, 99.999% Ar gas is filled into the aluminum liquid for refining degassing, the Ar gas flow is 20 L / min, the refining time is 25 min, and the hydrogen content in the treated aluminum melt is ≤0.12 ml / 100g after the aluminum liquid is placed and temperature-adjusted.

[0044] (3) Online filtering: a two-stage filtering device is used for online degassing, deslagging and filtering of the aluminum melt; the removal rate of inclusions with a particle size greater than 1 μm in the aluminum melt is controlled to be greater than 90%.

[0045] (4) Continuous casting: the casting temperature ranges from 710°C to 720°C, the crystallization wheel is provided with a water cooling system, the cooling water temperature ranges from 15°C to 30°C, the aluminum liquid is cooled and solidified into a φ9.5 mm aluminum rod blank by the crystallization wheel, and the casting speed is 100-120 kg / h.

[0046] (5) Continuous extrusion: after the aluminum rod is scraped to remove the surface oxide skin, cleaned and preheated, the aluminum rod is pressed into the extrusion wheel groove by the compaction wheel, the rotation speed of the extrusion wheel is 7 r / min, and a 2.7 mm diameter wire blank is obtained.

[0047] (6) Intermediate annealing: heating to 320°C for 2 hours, holding at 320°C for 1.5 hours, cooling to 270°C for 2 hours, holding at 270°C for 3.5 hours, and air cooling after discharge.

[0048] (7) Drawing and scraping: the annealed wire blank is drawn to a near-finished size of φ1.2 mm at a speed of 4-6 m / s, and then the surface scratches and fatigue layer are scraped off by two continuous skinning and scraping at a speed of 3-5 m / s.

[0049] The Al-Zn-Mg-Sc aluminum alloy wire with the above composition is used for cold metal transition (CMT) printing for arc additive manufacturing, and the printing process parameters are as follows: current 90 A, voltage 11.8 V, printing speed 540 mm / min, protective gas (argon) flow rate 18 L / min, and arc swing printing. During cold metal transition (CMT) printing, the welding gun swings horizontally along the forward direction at an angle of 30 degrees. The arc swing welding technology is introduced into arc additive manufacturing, which can well eliminate the anisotropy of the printed part. The prepared aluminum alloy printed body is shown in Figure 1 .

[0050] According to the standard GB / T228.1-2021 tensile test, the mechanical property data is as shown in Table 1:

[0051] Table 1

[0052]

[0053] Example 2: The chemical composition (mass percentage) of the designed Al-Zn-Mg-Sc aluminum alloy wire is: Cu 0.08%, Zn 5.4%, Mn 0.43%, Mg 2.8%, Zr 0.23%, Sc 0.35%, Ti 0.03%, Si 0.05%, Fe 0.09%, Cr 0.21%, Be 0.0005%, and the rest is Al. The Al-Zn-Mg-Sc aluminum alloy wire with the above composition is used for arc additive manufacturing by cold metal transfer (CMT) printing, and the printing process parameters are as follows: current 90 A, voltage 11.8 V, printing speed 540 mm / min, protective gas (argon) flow rate 18 L / min, see Figure 2 .

[0054] According to the standard GB / T228.1-2021 tensile test, the mechanical property data are as shown in Table 2:

[0055] Table 2

[0056]

[0057] Example 3: The chemical composition (mass percentage) of the designed Al-Zn-Mg-Sc aluminum alloy wire is: Cu 0.06%, Zn 5.0%, Mn 0.46%, Mg 3.3%, Zr 0.21%, Sc 0.30%, Ti 0.05%, Si 0.05%, Fe 0.08%, Cr 0.22%, Be 0.0008%, and the rest is Al. The Al-Zn-Mg-Sc aluminum alloy wire with the above composition is used for arc additive manufacturing by cold metal transfer (CMT) printing, and the printing process parameters are as follows: current 110 A, voltage 12.5 V, printing speed 540 mm / min, protective gas (argon) flow rate 18 L / min, and arc swing printing.

[0058] According to the standard GB / T228.1-2021 tensile test, the mechanical property data are as shown in Table 3, and the metallographic structure is as shown in Figure 3

[0059] Table 3

[0060]

[0061] Comparative Example 1

[0062] The aluminum alloy wire of Example 1 of patent CN111471905A is printed, and arc additive manufacturing is carried out by cold metal transfer (CMT) printing, and the printing process parameters and heat treatment system are completely consistent with Example 3.

[0063] According to the standard GB / T228.1-2021 tensile test, the mechanical property data are as shown in Table 4, and the metallographic structure is as shown in​Figure 4 as shown:

[0064] Table 4

[0065]

[0066]

[0067] In the embodiment 1 of the Chinese patent application with the publication number CN111471905A, the mass percentage of Zn in the aluminum alloy wire material composition is 6.5%, while the mass percentages of Sc and Zr are only 0.1% and 0.05%. Zn can significantly improve the strength of the material, but is not conducive to the improvement of the welding performance and the elongation. The contents of Sc and Zr are low, and the elongation cannot be improved. Although the swing arc printing can eliminate the directionality, after the same T6 heat treatment, the number of grain boundary precipitated phases is obviously more than that in the embodiment 3, resulting in that the elongation is only 6%, while the yield strength ratio is ≥91%, which affects the use of the material.

[0068] The content illustrated in the above embodiments should be understood as that the embodiments are only used for more clearly illustrating the present application, and are not used for limiting the scope of the present application. After reading the present application, the modification of various equivalent forms of the embodiments by the person skilled in the art all fall within the scope defined by the appended claims of the present application.

Claims

1. An Al-Zn-Mg-Sc alloy, comprising, by mass percentage, the following alloying elements: Zr content 0.15~0.25%, Sc content 0.225~0.375%, Ti content ≤0.1%, characterized in that, Cu content ≤0.1%, Zn content 4.0~5.5%, Mn content 0.2~0.6%, Mg content 2.0~4.0%, Cr content 0.1~0.3%, Be content 0.0001-0.005%, balance Al; 7.5%≤w(Zn+Mg)≤9.5%, and w(Zn):w(Mg)≤2.5; w(Mn): w(Cr) = 2; w(Sc): w(Zr) = 1.5; w(Zn+Mg) is the sum of the mass contents of Zn and Mg, and w(Zn), w(Mg), w(Mn), w(Cr), w(Sc), and w(Zr) refer to the mass percentages of Zn, Mg, Mn, Cr, Sc, and Zr, respectively.

2. The Al-Zn-Mg-Sc alloy according to claim 1, characterized in that, Fe ≤ 0.1%, Si content ≤ 0.05%, individual impurity element ≤ 0.05%, total impurity ≤ 0.15%.

3. The Al-Zn-Mg-Sc alloy according to claim 1, characterized in that, H content ≤ 0.15 mL / 100 g Al.

4. The Al-Zn-Mg-Sc alloy according to claim 1, characterized in that, Its grain size D90 is distributed in the range of 0~30μm.

5. An application of an Al-Zn-Mg-Sc alloy in arc additive manufacturing, characterized in that, Arc additive manufacturing is performed using the Al-Zn-Mg-Sc alloy as described in any one of claims 1-4 as the filler material. The printing process parameters are: current 90-130A, voltage 9.4-12.5V, printing speed 450-620mm / min, protective gas flow rate 18-25L / min, and oscillating arc printing.

6. The application according to claim 5, characterized in that, The protective gas is argon with a purity of 99.999%.

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