Aluminium alloy and aluminium wire material

Abstract

The invention relates to the field of metallurgy, and more particularly to wire materials based on aluminium alloys which can be used for producing articles using cladding and additive manufacturing techniques. Experimentally selected to solve the problem of interest, the component composition of the proposed aluminium alloy imparts high physical and mechanical properties and low porosity to finished articles produced using hybrid additive manufacturing techniques, and the claimed material has a low density and good weldability.

Description

[0001] ALUMINUM ALLOY AND ALUMINUM WIRE MATERIAL

[0002] Field of technology to which the invention relates

[0003] The invention relates to the field of metallurgy, namely, to an aluminum alloy and a wire material based on an aluminum alloy, used for the manufacture of products using surfacing and additive manufacturing methods.

[0004] State of the art

[0005] Currently, the development of modern production methods, such as additive technologies, allows for the production of large-sized and complex-shaped products, since they do not have the limitations inherent in traditional materials processing technologies. They allow for the elimination of many limitations and the development of new approaches and solutions in the design and construction of new units and assemblies for products in high-tech industries, such as aircraft and rocket engineering, mechanical engineering and the automobile industry.

[0006] The emergence and development of new technologies requires the creation of new high-tech materials with a high level of physical and mechanical characteristics, unique properties and high economic efficiency. One of the most popular and technologically advanced basic materials in traditional and additive technologies is aluminum and its alloys, which have high physical and mechanical, specific and economic indicators.

[0007] In the history of modern technology development, there is a tendency towards the emergence of production processes at the junction of several technologies, which is called hybrid production methods. As a rule, this is a combination of new methods for manufacturing products that complement each other and allow eliminating their individual shortcomings. One of these methods based on additive manufacturing, which has received the greatest development, is the wire-arc surfacing technology with direct supply of material to the product synthesis zone (WAAM technology - Wire Arc Additive Manufacturing, "wire-arc additive manufacturing"). This method allows obtaining complex-shaped large-sized structures with a high material utilization factor (MUF), as well as carrying out their restoration and repair using surfacing technology.The use of welding wire made from aluminum materials allows us to provide products with high functional, technological and mechanical characteristics.

[0008] Currently, existing materials based on the aluminum-magnesium system achieve high mechanical characteristics primarily due to an increase in the magnesium content in the alloy composition, as well as macroalloying with manganese and other elements. The introduction of a large amount of manganese and zinc into alloys leads to a significant increase in the strength of the material, but also negatively affects their plasticity. In turn, this imposes certain restrictions on the technical base of equipment intended for the production of wire semi-finished products, and complicates their production on low-power installations for their production.Therefore, the development and production of Al-Mg system wire materials with good weldability, high strength and plasticity compared to analogues when microalloyed with rare earth metals (REM) and allowing the production of products from them using additive manufacturing methods by wire-arc surfacing with direct material supply is becoming an urgent task.

[0009] Patent documents W02007020041, RU2280705, DE60002061, WO9942627, RU2343218, RU2268319, WO2017077137A9 propose alloys of various compositions, which determine their use in finished products, considered below as analogues, which have a number of disadvantages, the proposed invention is aimed at eliminating.

[0010] International application W02007020041 describes an aluminum alloy product with high strength in the deformed state, good corrosion resistance, but limited weldability, and the high content of manganese and zinc significantly reduces the plastic properties of the material and its welded joints. The high content of silver and scandium significantly increases the cost of the material. The chemical composition of the alloy is represented by the following elements in mass %:

[0011] Magnesium 3.5-6, O

[0012] Manganese 0.4-1.2

[0013] Iron <0.5

[0014] Silicon <0.5

[0015] Copper <0.15

[0016] Zirconium <0.5

[0017] Chromium <0.3

[0018] Titanium 0.03-0.2 Scandium <0.5

[0019] Zinc <1.7

[0020] Lithium <0.5

[0021] Silver <0.4 Aluminum the rest

[0022] An alloy used in the aerospace industry for welded structures subject to medium loads is also known (patent RU2280705). The alloy belongs to the magnalia class and has the following chemical composition in mass %:

[0023] Magnesium 4.5-6.5

[0024] Manganese 0.2-1.2

[0025] Zinc <0.2

[0026] Chromium <0.2

[0027] Titanium <0.15

[0028] Silicon <0.25

[0029] Iron <0.3

[0030] Copper <0.1

[0031] Zirconium <0.05-0.3

[0032] Beryllium 0.0001-0.01

[0033] Scandium 0.05-0.3

[0034] Yttrium 0.001-0.1

[0035] Neodymium 0.001-0.1;

[0036] Cerium 0.001-0.1 Aluminum the rest.

[0037] The alloy is intended for obtaining deformed semi-finished products at high temperatures with subsequent multi-hour heat treatment. The maximum strength of the material is achieved with a high content of alloying elements; it can be welded. The strength of welded joints reaches 322 MPa. However, the features of the technological process of material processing affect the cost of the final products, and the high content of manganese leads to a decrease in plastic characteristics.

[0038] An aluminum alloy from DE60002061, adopted as a prototype, is known, having the following chemical composition of components in mass %:

[0039] Magnesium 3.5-6.0

[0040] Manganese 0.4- 1.2

[0041] Zinc 0.4- 1.5 Zirconium <0.25

[0042] Chromium <0.3

[0043] Titanium <0.2

[0044] Iron <0.5

[0045] Silicon <0.5

[0046] Copper <0.4

[0047] One or more elements from the group:

[0048] Tin 0.01-0.1

[0049] Silver 0.01-0.5

[0050] Scandium 0.01-0.5

[0051] Lithium 0.01-0.5

[0052] Vanadium 0.01-0.3

[0053] Cerium 0.01-0.3

[0054] Yttrium 0.01-0.3

[0055] Nickel 0.01-0.3

[0056] Bismuth 0.005-0.1

[0057] Lead 0.005-0.1

[0058] Aluminum rest

[0059] Products from the alloy can be obtained by various pressure processing mechanisms in the form of rolling or extrusion. The alloy is intended for use in welded structures of land and sea transport. The strength of the welded joint of the alloy is 349 MPa. High over-alloying of the alloy composition, especially the introduction of silver and scandium in a concentration close to the upper limit, significantly increases the cost of its manufacture. The presence of manganese and zinc in the alloy leads to an increase in strength and at the same time to a decrease in the plasticity of the material, which has a negative effect on the characteristics of the welded joint, which can be critical when using additive manufacturing methods.

[0060] All analogues have a common drawback in the absence of an optimally selected alloy composition that provides the necessary properties for obtaining deformable semi-finished products and articles, including welding wire, which provides a combination of high strength and plasticity of final products and structures obtained by additive manufacturing methods using wire-arc surfacing with direct supply of material to the melting zone using the principle of microalloying to increase economic efficiency. Disclosure of the essence of the invention

[0061] The technical task and result of the proposed invention is the development and production of a new aluminum material that can be used to produce deformable semi-finished products and articles, including welding wire, which provides a combination of high strength and plasticity of final articles and structures obtained by additive manufacturing methods using wire-arc surfacing with direct supply of material to the melting zone using the principle of microalloying to increase economic efficiency.

[0062] To solve the stated problem and achieve the corresponding result, a new and non-obvious composition of aluminum alloy is proposed, providing high physical and mechanical properties and low porosity of finished products obtained by hybrid additive manufacturing methods, possessing low density and good weldability. The stated technical problem is solved, and the technical result is achieved by obtaining an alloy and aluminum wire material containing elements in the following ratio in mass %:

[0063] Magnesium 2.8 - 6.2

[0064] Scandium 0.1 - 0.35

[0065] Zirconium 0.05 - 0.2

[0066] Zinc 0.1 - 0.25

[0067] Chrome OD - o,z

[0068] Vanadium 0.01 - 0.15

[0069] Titanium 0.01 - 0.1

[0070] Strontium 0.003 - 0.08

[0071] Lanthanum and / or cerium 0.02 - 0.25

[0072] The rest is aluminum and inevitable impurities.

[0073] The proposed material has a grain homogeneous structure based on a solid solution of aluminum with structural component sizes of 2-10 μm and inclusions of dispersoids based on Al-(Zr,Sc), Al-Cr-Mg, Al-Mg-Cr-Ti systems with sizes less than 5 μm. A product made of a synthesized material using hybrid additive technologies, made of wire aluminum material, is also declared.

[0074] Brief description of the drawings

[0075] The drawings show:

[0076] Fig. 1 - External view of the synthesized workpiece. Fig. 2 - External view of the synthesized workpiece with defects due to violation of the ranges of component content.

[0077] Fig. 3 - Microstructure of the synthesized material obtained using wire-arc surfacing technology with direct material supply.

[0078] Fig. 4 - Porosity of the synthesized material obtained using wire-arc surfacing technology with direct material supply.

[0079] Detailed description of the essence of the invention

[0080] The component composition of the proposed aluminum alloy, experimentally selected to solve the problem, ensures high physical and mechanical properties and low porosity of finished products obtained by hybrid additive manufacturing methods; the material has low density and good weldability.

[0081] The presence and content of magnesium in the selected range ensures the required strength and processability of the material during the production of semi-finished products and welding wire, as well as to ensure high mechanical characteristics of final products and structures obtained from the synthesized material by using hybrid-additive surfacing units. Magnesium provides strengthening by two mechanisms: solid-solution strengthening of the aluminum matrix and dispersion strengthening of the grain structure.

[0082] Unlike the prototype and known analogues, the alloy and, accordingly, the material do not contain manganese and the zinc content is limited. The introduction of manganese into aluminum leads to an increase in the strength of the alloy. However, its introduction leads to a significant decrease in the plastic characteristics of crack resistance in the material, which is critical in the manufacture of products using additive manufacturing methods. When they are introduced, the material is strengthened and the strength characteristics increase, while the plastic characteristics of semi-finished and finished products decrease. The introduction of zinc leads to an increase in strength and an increase in the strengthening effect from alloying magnesium and manganese, but significantly reduces the casting and corrosion properties of the material. The simultaneous introduction of manganese and zinc leads to a significant increase in the strength characteristics of materials, but at the same time to a decrease in their plasticity and manufacturability.

[0083] The introduction of transition elements (Sc, Zr, Cr, V) into the aluminum-magnesium matrix is ​​due to the fact that it improves the characteristics of the system not only due to the individual contribution of each element, but also due to the mutual complex effect, allowing to increase the mechanical characteristics of the material, its corrosion resistance and weldability.

[0084] The introduction of zirconium into the alloy leads to additional strengthening of the material, increases the recrystallization temperature, and in combination with other elements enhances the effect of their impact. Thus, the addition of scandium as an alloying component in the range of 0.1-0.35 wt. % allows to significantly strengthen the solid solution of aluminum, similarly to zirconium to increase the recrystallization temperature and improve the weldability of the material. Additionally, it is possible to isolate secondary coherent dispersoids of stoichiometric composition AhSc, released as a result of low-temperature annealing, having high stability and positively affecting the strength characteristics, as well as the stability of the material structure.At the same time, zirconium partially replaces scandium atoms in the AhSc compound (up to 30%), allowing a reduction in the amount of scandium introduced and increasing the economic efficiency of the composition, on the one hand, and also enhancing the effect of strengthening the material by the dispersion mechanism, therefore it is advisable to limit its introduction to 0.2 wt.%.

[0085] The addition of chromium to the alloy composition, together with titanium and vanadium, allows not only to increase the level of physical and mechanical properties of the material, but also to additionally stabilize the uniformity of the structural state due to the fact that the most preferential location of these elements is in the volume of the grain body or dendritic cell.

[0086] Strontium as a modifier allows to improve the structure, to further reduce the average size of structural components, however, when its content is more than 0.08 mass. %, the effect is leveled out, therefore it is advisable to limit its upper limit.

[0087] Introduction of rare earth elements (REE) in a given range allows achieving several effects, namely modifying eutectic inclusions of aluminum-magnesium eutectic by adding cerium, which improves the morphology of structures and its contribution to the mechanical properties of the material, lanthanum in turn leads to an increase in the weldability of the material. Taking into account the complex effect of the selected chemical elements and their concentrations, it is additionally worth noting that elements that have good solubility in aluminum and form solid solutions with it by eutectic reactions (Mg, Zn, La, Sr) provide strengthening of the peripheral boundaries of the grain structure. At the same time, transition elements and some rare earth metals (Sc, Cr, Ce, Ti, Zr, V), interacting by a peritectic mechanism, allow increasing the level of mechanical and physical properties of the material due to the preferential location in the body of a grain or structural unit.This comprehensive approach allows us to obtain a uniform structure of the material, increase the level of properties of the aluminum matrix by various mechanisms and achieve the required parameters taking into account various types of material processing, both classical technological processes and hybrid additive methods.

[0088] The content of lanthanum and cerium is given as alternatives, i.e. together (in total) or separately.

[0089] Wire material can be obtained using traditional technological methods, as well as using combined casting and pressing processes.

[0090] The proposed invention is illustrated by the following examples.

[0091] Example 1

[0092] At the first stage, the material batching was calculated, as well as additional components required for smelting (flux preparations). The melt was prepared at the smelting complex installation, using primary aluminum grade A85, with subsequent addition of alloying elements in proportion to the material batching calculations performed.

[0093] At the first stage, aluminum grade A85 was melted, followed by heating the melt to a temperature of 750-800 °C, and cerium and lanthanum were added to the melt in portions with stirring until complete dissolution. Then the remaining alloying elements were added at a melt temperature in the range of 750-850 °C. Vanadium was added in several batches with holding and stirring of the melt. Next, chromium ligature was added, followed by zirconium, while dissolution was accompanied by active stirring with intermediate holdings for heating. Then titanium and scandium were added, also in portions and with holding; when adding scandium, the temperature was increased by 30 °C. After scandium, magnesium grade Mg90 was added using chloride flux to avoid burnout of the alloy component. Then the melt was thoroughly stirred and zinc was added. Lastly, strontium was added in the specified temperature range.Before each pouring, the melt was treated with the flux preparation “Carnalite” in a ratio of 1 kg per ton of melt.

[0094] The technology of smelting all the compositions corresponded to the above, except for the introduction of the remaining components. Slag was removed from the melt surface and samples were taken to control the chemical composition. Based on the results of the express analysis, the chemical composition was adjusted to the calculated value. The chemical composition of the obtained compositions (Table 1) was determined using an atomic emission spectrometer with inductively coupled plasma.

[0095] The obtained blanks were pressed and drawn to produce wire with a diameter of 1.2 mm in accordance with GOST 7871-2019, from which samples were cut to determine the mechanical characteristics in accordance with GOST 10446-80 and GOST 1497-84. The samples were pre-annealed at 540 °C for 3 hours to remove work hardening. Tensile tests were carried out in accordance with GOST 1497-84 on a universal tensile testing machine MTS Criterion 40. The test results are presented in Table 2.

[0096] Table 1

[0097] Table 2 From the data in Tables 1 and 2 it is evident that the proposed aluminum wire material has high mechanical characteristics and good processability. Increasing the content of magnesium and other alloying elements in the specified ranges leads to an increase in the strength characteristics of wire semi-finished products while maintaining high plasticity of the material, which exceeds the values ​​of the selected prototype and known analogues.

[0098] Example 2

[0099] From the aluminum wire material obtained by analogy with example 1 using the wire-arc additive manufacturing installation, blanks for conducting studies were synthesized (Fig. 1), the composition is indicated in Table 3. The wire material compositions corresponding to the selected concentration range showed good weldability and a stable surfacing process (compositions 2-5). For compositions (1 and 6) outside the range of the selected content of alloying elements, the formation of surface defects associated with the features of the crystallization of the material was observed (Fig. 2). In alloy 1, the growth process was accompanied by an unstable nature of the melt bath, resulting in the formation of local build-ups and drips; in a more alloyed composition, the number of defects and the stability of the process were much worse.When surfacing with a wire of chemical composition corresponding to the selected prototype, burnout of alloying elements was observed during the growth process, which was accompanied by splashing of metal droplets and the formation of uneven walls of the blanks.

[0100] Table 3 Samples were cut out from the obtained blanks for conducting the studies. The microstructure of the material synthesized from compositions 2-5, lying in the range of the selected concentrations, is represented by a solid solution of aluminum with alloying elements dissolved in it and a large number of dispersoids uniformly distributed throughout the volume of the material (Fig. 3). In all alloys, the allocation of dispersoids with a dual morphology is observed in the volume of the aluminum matrix - on the one hand, tending to spheroid shaping, which basically contain compounds with magnesium and chromium, and on the other - with titanium and zirconium, such dispersoids have local halos enriched with them (compositions 2-5). In compositions without the addition of cerium, lanthanum and strontium, the morphology of the structure is rougher. Often, a multifaceted form of dispersoids close to lamellar is found in the structure.The vertices of such structural units are stress concentrators and affect the plastic characteristics of the synthesized material (compositions 1 and 6) (Fig. 3).

[0101] Samples were cut from the obtained blanks to conduct porosity studies. Evaluation of the porosity of the synthesized material according to GOST 9191-80 showed that in compositions with component concentrations lying outside the proposed ranges, the porosity values ​​were higher than 2%, which is the upper permissible limit for their use (Fig. 4). The results of the porosity evaluation are presented in Table 4.

[0102] Table 4

[0103] Example 3

[0104] From several blanks (composition 4, 5 and Prototype), obtained according to example 2, flat samples were cut out to evaluate the mechanical characteristics according to GOST 1497-84. The samples were preliminarily subjected to heat treatment at 350°C for 3 hours. The obtained test results are presented in table 5. The synthesized material has higher plasticity compared to the prototype, while being less alloyed and more cost-effective. Table 5

[0105] Example 4

[0106] The optimal composition for the manufacture of products with a combination of a high level of physical and mechanical characteristics, good weldability, low porosity and high technological efficiency at all stages of production, according to examples 1-3, is the composition presented in Table 6.

[0107] Table 6

[0108] Thus, the chemical composition of the proposed alloy allows obtaining a synthesized material and products from it that have, in comparison with the prototype, average strength, low porosity, good weldability and manufacturability, higher plasticity, and allows its use in hybrid additive manufacturing using the wire-arc surfacing method with direct supply of material to the product synthesis zone (WAAM technology).

[0109] According to the proposed formula of the invention, the scope of legal protection is requested for an aluminum-based alloy for the manufacture of products by surfacing and additive manufacturing methods, containing magnesium, scandium, zirconium, zinc, chromium, vanadium, titanium, cerium, lanthanum, strontium. With the following content of components taking into account aluminum and associated impurities, mass %:

[0110] Magnesium 2.8 - 6.2

[0111] Scandium 0.1 - 0.35

[0112] Zirconium 0.05 - 0.2

[0113] Zinc 0.1 - 0.25

[0114] Chrome 0.1 - 0.3

[0115] Vanadium 0.01 - 0.15

[0116] Titanium 0.01 - 0.1 Strontium 0.003 - 0.08

[0117] Lanthanum and / or cerium 0.02 - 0.25

[0118] The rest is aluminum and inevitable impurities.

[0119] A wire aluminum material obtained from an alloy having a grain homogeneous structure based on a solid aluminum solution is also proposed. Preferably, the grain homogeneous structure based on a solid aluminum solution has structural component sizes of predominantly 2-10 μm and inclusions of dispersoids having a predominantly spherical morphology of particles with predominant sizes of less than 5 μm. A product made from a synthesized material using hybrid additive technologies, made from a wire aluminum material, is also proposed.

Claims

CLAUSE OF THE INVENTION 1. An aluminum-based alloy for the manufacture of products using surfacing and additive manufacturing methods, containing magnesium, scandium, zirconium, zinc, chromium, vanadium, titanium, cerium, lanthanum, strontium with the following content of components taking into account aluminum and associated impurities, mass %: Magnesium 2.8 - 6.2 Scandium 0.1 - 0.35 Zirconium 0.05 - 0.2 Zinc 0.1 - 0.25 Chrome 0.1 - o,z Vanadium 0.01 - 0.15 Titanium 0.01 - 0.1 Strontium 0.003 - 0.08 Lanthanum and / or cerium 0.02 - 0.25 The rest is aluminum and inevitable impurities.

2. A wire aluminum material obtained from an alloy according to item 1, having a grain homogeneous structure based on a solid solution of aluminum.

3. A wire aluminum material according to claim 2, in which the grain homogeneous structure based on a solid solution of aluminum has structural component sizes of predominantly 2-10 μm and inclusions of dispersoids having a predominantly spherical particle morphology with predominant sizes of less than 5 μm.

4. An article made from a synthesized material using hybrid additive technology methods, made from a wire aluminum material according to item 2 or item 3.

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