Preparation method of aluminum alloy welding wire and high-strength 7xxx aluminum alloy welding wire prepared through preparation method

Abstract

The invention relates to a preparation method of an aluminum alloy welding wire and a high-strength 7xxx aluminum alloy welding wire prepared thereof.The preparation method comprises the following steps that S1, an aluminum alloy cast ingot is cast, and the aluminum alloy cast ingot comprises, by mass, 7%-8% of Zn, 2.0%-2.3% of Mg, 1.2%-1.8% of Cu, 0.2%-0.3% of Sc, 0.2%-0.3% of Zr, 0.1%-0.2% of Er and the balance Al; s2, the aluminum alloy cast ingot is subjected to multi-stage homogenization treatment, hot extrusion treatment, solution treatment, cold drawing, three-stage annealing treatment, cold drawing, three-stage annealing treatment, cold drawing, scraping cleaning and drying; multi-element microalloying, deformation and heat treatment are combined, precipitation strengthening, fine grain strengthening, strain strengthening, element diffusion and segregation and the like are fully considered, the formability of the welding wire is improved while the components of the welding wire are guaranteed, the technological method is simple, and operation is convenient.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of material preparation, in particular to a preparation method of an aluminum alloy welding wire and a high-strength 7xxx aluminum alloy welding wire prepared by the method. BACKGROUND

[0002] High-strength aluminum alloys, especially 7xxx series aluminum alloys with Zn-Mg-Cu as the main alloying elements, are widely used in aerospace, national defense and military industry, rail transportation and other high-end equipment manufacturing fields due to their high specific strength, good processability and excellent comprehensive mechanical properties. In the structural manufacturing of these fields, welding is an indispensable key connection technology, and the performance of the welding wire as the filler material in the aluminum alloy welding process directly determines the quality of the welded joint and the reliability of the structure. At the same time, with the development of additive manufacturing technology, aluminum alloy welding wires are also widely used in arc additive manufacturing, and their performance directly determines the performance of the additive manufactured aluminum alloy.

[0003] However, the current application of 7xxx aluminum alloy welding wires in the fields of welding and additive manufacturing faces many severe technical challenges, mainly in the following aspects: (1) The main strengthening phase of 7xxx alloy is MgZn (η phase), and the existing technology can achieve very high strength through high Zn and Mg content and aging treatment, but high alloying also leads to the precipitation of continuous coarse second phase (such as η phase) at the grain boundary, which cuts the matrix, affects the forming effect and mechanical properties of the finished product of the welding wire, and significantly reduces the plasticity and toughness of the material. (2) The existing high-strength 7xxx alloy welding wire cannot balance high strength and high plasticity, which is not conducive to stable additive manufacturing and affects the mechanical properties of the additive manufactured product. (3) 7xxx aluminum alloy belongs to heat-treatable strengthening aluminum alloy, while the welding and additive manufacturing process is a non-uniform heat cycle process: the weld metal undergoes melting and solidification to become a cast structure, while the heat-affected zone (HAZ) undergoes over-aging or partial remelting, leading to the coarsening or dissolution of the original nanoscale strengthening phase in the base material, thereby forming a clear "softening zone" in the heat-affected zone (especially the over-aging zone). The strength of this area is usually much lower than that of the base material, becoming a weak link of the entire welded structure, and the joint strength coefficient (joint strength / base material strength) is usually only between 50% and 70%, which is difficult to improve.

[0004] In order to cope with the above challenges, the traditional solutions mainly focus on optimizing the main components of the alloy (adjusting the Zn / Mg ratio) and improving the single heat treatment process (such as T6 peak aging). However, these methods often have limited effect: for example, simply reducing the alloy content can improve plasticity and crack resistance, but at the expense of strength; and a single heat treatment process in the alloy preparation process cannot achieve precise control of the morphology, size and distribution of multiple precipitates. SUMMARY

[0005] Based on this, the purpose of the present application is to provide a preparation method of aluminum alloy welding wire, through which high-strength 7xxx aluminum alloy welding wire with uniform composition and fine structure can be obtained, which is suitable for welding and additive manufacturing of 7xxx aluminum alloy, the process is simple, easy to operate, and the obtained welding wire has excellent performance.

[0006] The specific technical solutions and steps of the present application are as follows:

[0007] A preparation method of aluminum alloy welding wire, comprising the following steps:

[0008] S1: melt and cast aluminum alloy ingot, the mass percentage of the components in the aluminum alloy ingot is:

[0009] Zn 7-8wt%, Mg 2.0-2.3wt%, Cu 1.2-1.8wt%, Sc 0.2-0.3wt%, Zr 0.2-0.3wt%, Er 0.1-0.2wt%, and the balance is Al;

[0010] S2: the aluminum alloy ingot is subjected to multi-stage homogenization treatment, hot extrusion treatment, solid solution treatment, cold drawing, three-stage annealing treatment, cold drawing, three-stage annealing treatment, cold drawing, scraping and cleaning, and drying.

[0011] The combined effect of micro-alloying and multi-stage heat treatment is a very potential strategy to solve the above problems. Micro-alloying elements introduce high-stability nano-core, and then multi-level and multi-scale microstructure regulation is carried out by using multi-stage heat treatment, which is expected to synergistically optimize the as-cast structure, precipitate characteristics and comprehensive performance of 7xxx aluminum alloy welding wire. The preparation method of the aluminum alloy welding wire of the present application adds Sc, Zr and Er for multi-element micro-alloying design, and combines micro-alloying with multi-stage heat treatment technology through reasonable heat treatment process: let Sc, Zr and Er dissolve into the alpha-Al matrix, and then pass through three-stage homogenization and three-stage annealing treatment in the welding wire preparation process, to ensure that the alloy elements are analyzed in turn and do not coarsen obviously. Since the diffusion coefficients of the three alloy elements in alpha-Al satisfy the following relationship: Er > D Sc > D ZrTherefore, Er is precipitated at a lower temperature first to form an Al3Er precipitate; then the temperature is increased to precipitate Sc outside the Al3Er to form an Al3(Sc, Er) phase with a core-shell structure taking Al3Er as the core and Al3Sc as the shell; when the aging temperature is continuously increased, Zr is precipitated outside the Al3(Sc, Er) to form an Al3(Sc, Zr, Er) precipitate with a double-core-shell structure taking Al3Er as the core, Al3Sc as the inner shell and Al3Zr as the outer shell; the Al3(Sc, Zr, Er) precipitate is coherent with the matrix, which can effectively improve the strength of the alloy, and meanwhile, the Al3(Sc, Zr, Er) precipitate can refine the grains to improve the toughness and elongation of the aluminum alloy, so that the welding wire is not easy to break in the drawing forming process. In addition, the preparation method of the aluminum alloy welding wire of the application adopts a process of cold drawing-three-stage annealing treatment alternating with each other, which is different from the common process, on the one hand, the dislocations introduced by cold drawing can promote the nucleation of precipitates in the subsequent annealing aging process, which is beneficial to the improvement of the strength of the alloy; on the other hand, the welding wire wire rod obtained by drawing is composed of elongated grains, and there are a large number of dislocations in the grains, and the multi-stage annealing process after drawing can not only play the annealing effect to eliminate the adverse effects of the dislocations introduced in the drawing process on the elongation and residual stress, but also can recrystallize the deformation structure generated by drawing to form fine recrystallized grains, which is beneficial to the further improvement of the elongation of the alloy. The preparation method of the aluminum alloy welding wire of the application combines melting, casting, heat treatment, hot extrusion, annealing treatment and drawing to prepare a high-strength 7xxx aluminum alloy welding wire, fully considers precipitation strengthening, fine-grain strengthening, strain strengthening and element diffusion and segregation, etc., ensures that the welding wire itself has a good match of high strength and high plasticity, improves the formability of the welding wire, and obtains a welding wire that can be welded and additively manufactured with high quality, fundamentally improves the weldability and the performance of the additively manufactured components, and obtains a high-performance welded joint, which provides a feasible method for preparing a high-performance 7xxx aluminum alloy wire material, has industrial application potential, and has great theoretical significance and engineering value for promoting the welding application of high-strength aluminum alloys in key load-bearing structures.

[0012] Further, the three-stage annealing treatment of step S2: the first-stage annealing temperature is 250-275 DEG C, the holding time is 8-10h; the second-stage annealing temperature is 300-350 DEG C, the holding time is 8-10h; the third-stage annealing temperature is 375-450 DEG C, the holding time is 5-8h.

[0013] The annealing temperature has a great influence on the precipitation of alloy elements. If the annealing temperature is too low, the element diffusion is slow or even does not diffuse, and the element cannot be precipitated. If the annealing temperature is too high, the supersaturation of the alloy element in the alpha-Al is reduced, which directly reduces the nucleation rate of the precipitated phase, and is not conducive to the formation of the dispersed fine precipitated phase beneficial to the strength improvement. Therefore, a reasonable annealing aging process is the key to obtaining high performance of the multi-element micro-alloyed aluminum alloy. Due to the different diffusion coefficients of Sc, Zr and Er in alpha-Al, a reasonable three-stage annealing process is designed in the application. The first-stage annealing is performed at a lower temperature of 250-275 DEG C, corresponding to the precipitation of Al3Er; the second-stage annealing is performed at 300-350 DEG C, corresponding to the precipitation of Al3Sc; and the third-stage annealing is performed at 375-450 DEG C, corresponding to the precipitation of Al3Zr, which is beneficial to the formation of Al3(Sc, Zr, Er) precipitated phase. Through the three-stage annealing treatment, the alloy elements are finally precipitated, and the precipitated phase is dispersed and fine, which is helpful to the improvement of the strength and the elongation of the welding wire. At the same time, the residual stress gradient can be reduced, and the forming performance of the welding wire is further improved.

[0014] Further, in step S2, the deformation amount between the two three-stage annealing treatments is 30-40%.

[0015] Further, step S1 comprises the following specific steps:

[0016] S11: batching: the high-purity aluminum and the intermediate alloy are batched according to the above component mass percentage;

[0017] S12: melting and casting: the high-purity aluminum is melted, the intermediate alloy is added respectively, the melt is stirred sufficiently, a refining agent is added, the slag is removed, a degassing agent is added for degassing treatment of the melt, and the melt is cast into a preheated cast iron mold to obtain an ingot.

[0018] Further, in step S11, the intermediate alloy includes but is not limited to Al-Zn alloy, Al-Mg alloy, Al-Cu alloy, Al-Sc alloy, Al-Zr alloy and Al-Er alloy.

[0019] Further, in step S12, the melting temperature of the high-purity aluminum is 720-750 DEG C; the melting temperature of the intermediate alloy is 750-780 DEG C; and the preheating temperature of the cast iron mold is 150-250 DEG C.

[0020] Further, step S2 comprises the following specific steps:

[0021] S21: the multi-stage homogenization treatment: the ingot of step S1 is put into an air furnace, and heating and holding are carried out at three different temperature stages; the first stage is holding at 250℃ for 5h, the second stage is holding at 350℃ for 5h, and the third stage is holding at 420-450℃ for 2h. The above-mentioned multi-stage homogenization treatment of the ingot obtained by the melting of step S1 is beneficial to the formation of Al(Sc, Zr, Er) precipitated phase, ensures the homogenization before hot extrusion, and can also dissolve part of the coarse second phase formed during the casting of step S1, thereby improving the toughness of the material.

[0022] Further, step S2 further comprises the following specific steps:

[0023] S22: the hot extrusion treatment: the ingot after the homogenization of step S21 is held at a hot extrusion temperature of 400-420℃ for 1-2h, and then hot extruded into a rod; the diameter of the rod is 5mm.

[0024] S23: the solid solution treatment: the rod of step S22 is heated to 465-475℃ and held for 1-2h.

[0025] The holding of step S22 is beneficial to ensuring the uniformity of the temperature in the ingot; and the main purpose of the solid solution treatment of step S23 is to make the second phase in the rod fully dissolve, so as to prepare for cold drawing.

[0026] A high-strength 7xxx aluminum alloy welding wire prepared by any one of the above preparation methods.

[0027] In order to better understand and implement, the present application is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 A process flow chart of the preparation method of the high-strength 7xxx aluminum alloy. DETAILED DESCRIPTION

[0029] The present application is further described in detail below with reference to the specific examples, and the terms used in the examples of the present application are only for the purpose of describing the specific examples, and are not intended to limit the examples of the present application. It should be clear that the described examples are only some of the examples of the present application, but not all the examples, and the protection scope of the present application is not limited to the following examples. Based on the examples in the examples of the present application, all other examples obtained by those skilled in the art without creative labor are within the scope of protection of the examples of the present application.

[0030] The terms used in the embodiments of the present application are merely for the purpose of describing specific embodiments and are not intended to limit the embodiments of the present application. The singular forms "a," "an," and "the" used in the embodiments of the present application and the appended claims are intended to include plural forms as well, unless the context clearly indicates otherwise. In addition, the scope of the embodiments of the present application is limited only by the appended claims.

[0031] A method for preparing an aluminum alloy welding wire, comprising the following steps:

[0032] S1: melting and casting an aluminum alloy ingot, the aluminum alloy ingot comprising the following components in mass percentage:

[0033] Zn 7-8wt%, Mg 2.0-2.3wt%, Cu 1.2-1.8wt%, Sc 0.2-0.3wt%, Zr 0.2-0.3wt%, Er 0.1-0.2wt%, and the balance being Al;

[0034] S2: performing multi-stage homogenization treatment, hot extrusion treatment, solid solution treatment, cold drawing, three-stage annealing treatment, cold drawing, three-stage annealing treatment, cold drawing, scraping and cleaning, and drying on the aluminum alloy ingot to obtain a high-strength 7xxx aluminum alloy welding wire.

[0035] Further, the three-stage annealing treatment in step S2 has the following temperature and time: the first-stage annealing temperature is 250-275℃, the holding time is 8-10h; the second-stage annealing temperature is 300-350℃, the holding time is 8-10h; and the third-stage annealing temperature is 375-450℃, the holding time is 5-8h.

[0036] Further, in step S2, the deformation amount between the two three-stage annealing treatments is 30-40%.

[0037] Further, step S1 comprises the following specific steps:

[0038] S11: batching: batching high-purity aluminum and intermediate alloy according to the above-mentioned material atomic component mass percentage;

[0039] S12: melting and casting: melting the high-purity aluminum, separately adding the intermediate alloy, thoroughly stirring the melt, adding a refining agent, skimming the slag, adding a degassing agent to perform degassing treatment on the melt, standing and holding, and casting into a preheated cast iron mold to obtain an ingot.

[0040] Further, in step S11, the intermediate alloy includes but is not limited to Al-Zn alloy, Al-Mg alloy, Al-Cu alloy, Al-Sc alloy, Al-Zr alloy, and Al-Er alloy.

[0041] Further, in step S12, the melting temperature of the high-purity aluminum is 720-750 °C; the melting temperature of the intermediate alloy is 750-780 °C; and the preheating temperature of the cast iron mold is 150-250 °C.

[0042] Further, step S2 comprises the following specific steps:

[0043] S21: The multi-stage homogenization treatment: the ingot in step S1 is placed in an air furnace and heated and held at three different temperature stages.

[0044] Further, step S2 further comprises the following specific steps:

[0045] S22: The hot extrusion treatment: the ingot after the homogenization in step S21 is held at a hot extrusion temperature of 400-420 °C for 1-2 h, and then hot extruded into a rod; the diameter of the rod is 5 mm; the holding is beneficial to ensure uniform temperature in the ingot.

[0046] S23: The solution treatment: the rod in step S22 is heated to 465-475 °C and held for 1-2 h.

[0047] S24: Cold drawing and three-stage annealing treatment: the rod after the solution treatment in step S23 is alternately subjected to cold drawing, three-stage annealing treatment, cold drawing, three-stage annealing treatment, and cold drawing to obtain a welding wire. The three-stage annealing treatment: the first-stage annealing temperature is 250-275 °C, and the holding time is 8-10 h; the second-stage annealing temperature is 300-350 °C, and the holding time is 8-10 h; the third-stage annealing temperature is 375-450 °C, and the holding time is 5-8 h. The deformation amount between the two three-stage annealing treatments is 30-40%.

[0048] S25: Scraping and cleaning: the excess lubricant residues, slight oxidation layer, and other tiny attachments possibly generated in the drawing process on the surface of the welding wire in step S24 are removed through a mold.

[0049] S26: Drying: the welding wire after the scraping and cleaning treatment in step S25 is subjected to drying treatment in an oven or a hot air circulating drying furnace, the drying temperature is 100-200 °C, and the time is 2-5 h to ensure sufficient evaporation of moisture.

[0050] Further, in step S21, the first stage is held at 250 °C for 5 h, the second stage is held at 350 °C for 5 h, and the third stage is held at 420-450 °C for 2 h.

[0051] A high-strength 7xxx aluminum alloy welding wire prepared by any of the above preparation methods.

[0052] Example 1

[0053] A method for preparing a high-strength 7xxx aluminum alloy welding wire, comprising the following steps:

[0054] S1: melting and casting an aluminum alloy ingot, the aluminum alloy ingot comprising the following components in mass percentage:

[0055] Zn 7wt%, Mg 2.0wt%, Cu 1.2wt%, Sc 0.2wt%, Zr 0.2wt%, Er 0.1wt%, and the balance being Al;

[0056] Further, step S1 comprises the following specific steps:

[0057] S11: batching: high-purity aluminum and intermediate alloy are batched according to the above-mentioned material atomic component mass percentage. The intermediate alloy includes but is not limited to Al-Zn alloy, Al-Mg alloy, Al-Cu alloy, Al-Sc alloy, Al-Zr alloy, and Al-Er alloy.

[0058] S12: melting and casting: the high-purity aluminum is melted (melting temperature is 740℃), the intermediate alloy is separately melted (melting temperature is 760℃), the melt is fully stirred, a refining agent is added, slag is removed, a degassing agent is added for degassing treatment, the melt is placed in an environment at about 720℃ for 1h, and the melt is cast into a preheated cast iron mold at 150-250℃ to obtain an ingot.

[0059] S2: the aluminum alloy ingot is subjected to multi-stage homogenization treatment, hot extrusion treatment, solid solution treatment, cold drawing, three-stage annealing treatment, cold drawing, three-stage annealing treatment, cold drawing, scraping and cleaning, and drying.

[0060] Further, step S2 comprises the following specific steps:

[0061] S21: the multi-stage homogenization treatment: the ingot of step S1 is placed in an air furnace and heated and held at three different temperature stages: the first stage is held at 250℃ for 5h, the second stage is held at 350℃ for 5h, and the third stage is held at 450℃ for 2h.

[0062] S22: the hot extrusion treatment: the ingot after the homogenization treatment of step S21 is heated and held at a hot extrusion temperature of 410℃ for 1.5h, and then hot extruded into a rod with a diameter of 5mm.

[0063] S23: the solid solution treatment: the rod of step S22 is heated to 470℃ and held for 1.5h.

[0064] S24: Cold drawing and three-stage annealing: The bar material after solution treatment in step S23 is alternately subjected to cold drawing, three-stage annealing, cold drawing, three-stage annealing, and cold drawing to obtain welding wire. The three-stage annealing process is as follows: the first stage annealing temperature is 250℃, and the holding time is 10 hours; the second stage annealing temperature is 350℃, and the holding time is 10 hours; the third stage annealing temperature is 450℃, and the holding time is 7 hours. The deformation between the two three-stage annealing processes is 35%.

[0065] S25: Scraping and cleaning: Remove excess lubricant residue, slight oxide layer, and other minor deposits that may have formed on the surface of the welding wire in step S24 using a mold.

[0066] S26: Drying: The welding wire that has been scraped and cleaned in step S25 is dried using an oven or a hot air circulating drying oven.

[0067] Example 2

[0068] A method for preparing a high-strength 7xxx aluminum alloy welding wire includes the following steps:

[0069] S1: Cast aluminum alloy ingot, wherein the mass percentage of the components in the aluminum alloy ingot is:

[0070] Zn 7wt%, Mg 2.2wt%, Cu 1.5%, Sc 0.2wt%, Zr 0.2wt%, Er 0.1wt%, balance Al;

[0071] Furthermore, step S1 includes the following specific steps:

[0072] S11: Batching: High-purity aluminum and master alloy are batched according to the atomic composition mass percentages of the above materials. The master alloy includes, but is not limited to, Al-Zn alloy, Al-Mg alloy, Al-Cu alloy, Al-Sc alloy, Al-Zr alloy, and Al-Er alloy.

[0073] S12: Melting and casting: The high-purity aluminum is melted (melting temperature is 740℃), and the intermediate alloy is added separately (melting temperature is 760℃). The melt is stirred thoroughly, and a refining agent is added. Slag is removed, and a degassing agent is added to degas the melt. The melt is kept at a temperature of about 720℃ for 1 hour, and then cast into a cast iron mold preheated to 150-250℃ to obtain an ingot.

[0074] S2: The aluminum alloy ingot is subjected to multi-stage homogenization treatment, hot extrusion treatment, solution treatment, cold drawing, three-stage annealing treatment, cold drawing, three-stage annealing treatment, cold drawing, scraping and cleaning, and drying.

[0075] Further, the step S2 comprises the following specific steps:

[0076] S21: The multi-stage homogenization treatment: the ingot in step S1 is put into an air furnace and heated and kept at three different temperature stages: the first stage is kept at 250℃ for 5h, the second stage is kept at 350℃ for 5h, and the third stage is kept at 450℃ for 2h.

[0077] S22: The hot extrusion treatment: the ingot after the homogenization treatment in step S21 is kept at a hot extrusion temperature of 410℃ for 1.5h, and then hot extruded into a rod with a diameter of 5mm.

[0078] S23: The solution treatment: the rod in step S22 is heated to 470℃ and kept for 1.5h.

[0079] S24: Cold drawing and three-stage annealing treatment: the rod after the solution treatment in step S23 is alternately subjected to cold drawing, three-stage annealing treatment, cold drawing, three-stage annealing treatment, and cold drawing to obtain a welding wire. The three-stage annealing treatment: the first stage annealing temperature is 250℃, the holding time is 8h; the second stage annealing temperature is 350℃, the holding time is 8h; and the third stage annealing temperature is 450℃, the holding time is 7h. The deformation amount between the two three-stage annealing treatments is 35%.

[0080] S25: Scraping and cleaning: the excess lubricant residues, slight oxidation layer and other tiny attachments possibly generated in the drawing process on the surface of the welding wire in step S24 are removed by a mold.

[0081] S26: Drying: the welding wire after the scraping and cleaning treatment in step S25 is subjected to drying treatment by using an oven or a hot air circulating drying furnace.

[0082] Example 3

[0083] A preparation method of a high-strength 7xxx aluminum alloy welding wire, comprising the following steps:

[0084] S1: Melting and casting an aluminum alloy ingot, the aluminum alloy ingot comprises the following components in mass percentage:

[0085] Zn 8wt%, Mg 2.3wt%, Cu 1.8wt%, Sc 0.3wt%, Zr 0.3wt%, Er 0.2wt%, and the balance being Al;

[0086] Further, the step S1 comprises the following specific steps:

[0087] S11: batching: high-purity aluminum and intermediate alloy are batched according to the above-mentioned material atomic composition mass percentage. The intermediate alloy includes but is not limited to Al-Zn alloy, Al-Mg alloy, Al-Cu alloy, Al-Sc alloy, Al-Zr alloy, Al-Er alloy.

[0088] S12: smelting and casting: the high-purity aluminum is melted (melting temperature is 740℃), the intermediate alloy is separately melted (melting temperature is 760℃), the melt is fully stirred, a refining agent is added, slag is removed, a degassing agent is added to the melt for degassing treatment, the melt is placed in an environment at about 720℃ for 1h, and then cast into a cast iron mold preheated to 150-250℃ to obtain an ingot.

[0089] S2: the aluminum alloy ingot is subjected to multi-stage homogenization treatment, hot extrusion treatment, solid solution treatment, cold drawing, three-stage annealing treatment, cold drawing, three-stage annealing treatment, cold drawing, scraping cleaning, and drying.

[0090] Further, step S2 includes the following specific steps:

[0091] S21: the multi-stage homogenization treatment: the ingot of step S1 is placed in an air furnace and heated and held at three different temperature stages: the first stage is held at 250℃ for 5h, the second stage is held at 350℃ for 5h, and the third stage is held at 450℃ for 2h.

[0092] S22: the hot extrusion treatment: the ingot after the homogenization of step S21 is heated and held at a hot extrusion temperature of 410℃ for 1.5h, and then hot extruded into a rod with a diameter of 5mm.

[0093] S23: the solid solution treatment: the rod of step S22 is heated to 470℃ and held for 1.5h.

[0094] S24: cold drawing and three-stage annealing treatment: the rod after the solid solution treatment of step S23 is alternately subjected to cold drawing, three-stage annealing treatment, cold drawing, three-stage annealing treatment, and cold drawing to obtain a welding wire. The three-stage annealing treatment: the first stage annealing temperature is 250℃, the holding time is 8h; the second stage annealing temperature is 350℃, the holding time is 10h; the third stage annealing temperature is 450℃, the holding time is 10h. The deformation amount between the two three-stage annealing treatments is 35%.

[0095] S25: scraping cleaning: the excess lubricant residues, slight oxidation layer and other small attachments possibly generated in the drawing process on the surface of the welding wire of step S24 are removed by a mold.

[0096] S26: drying: the welding wire after the scraping cleaning treatment of step S25 is subjected to drying treatment by using an oven or a hot air circulating drying oven.

[0097] Comparative Example 1

[0098] A method for preparing a 7xxx aluminum alloy welding wire, comprising the following steps:

[0099] S1: melting and casting an aluminum alloy ingot, the aluminum alloy ingot having the following component mass percentage:

[0100] Zn 7wt%, Mg 2.0wt%, Cu 1.2wt%, and the balance being Al;

[0101] Further, step S1 comprises the following specific steps:

[0102] S11: batching: high-purity aluminum and intermediate alloy are batched according to the above-mentioned material atomic component mass percentage. The intermediate alloy includes but is not limited to Al-Zn alloy, Al-Mg alloy, and Al-Cu alloy.

[0103] S12: melting and casting: the high-purity aluminum is melted (melting temperature is 740℃), the intermediate alloy is separately melted (melting temperature is 760℃), the melt is fully stirred, a refining agent is added, slag is removed, a degassing agent is added for degassing treatment, and the melt is placed in an environment at about 720℃ for 1h, and then cast into a preheated cast iron mold at 150-250℃ to obtain an ingot.

[0104] S2: the aluminum alloy ingot is subjected to multi-stage homogenization treatment, hot extrusion treatment, solid solution treatment, cold drawing, three-stage annealing treatment, cold drawing, three-stage annealing treatment, cold drawing, scraping and cleaning, and drying.

[0105] Further, step S2 comprises the following specific steps:

[0106] S21: the multi-stage homogenization treatment: the ingot of step S1 is placed in an air furnace and heated and held at three different temperature stages: the first stage is held at 250℃ for 5h, the second stage is held at 350℃ for 5h, and the third stage is held at 450℃ for 2h.

[0107] S22: the hot extrusion treatment: the ingot after the homogenization of step S21 is heated and held at a hot extrusion temperature of 410℃ for 1.5h, and then hot extruded into a rod with a diameter of 5mm.

[0108] S23: the solid solution treatment: the rod of step S22 is heated to 470℃ and held for 1.5h.

[0109] S24: cold drawing and three-stage annealing treatment: the rod after the solution treatment of step S23 is alternately subjected to cold drawing, three-stage annealing treatment, cold drawing, three-stage annealing treatment, cold drawing to obtain the welding wire. The three-stage annealing treatment: the first-stage annealing temperature is 250℃, the holding time is 8h; the second-stage annealing temperature is 350℃, the holding time is 8h; the third-stage annealing temperature is 450℃, the holding time is 7h. The deformation between the two three-stage annealing treatments is 35%.

[0110] S25: scraping cleaning: the excess lubricant residues, slight oxidation layer and other tiny attachments possibly generated in the drawing process on the surface of the welding wire of step S24 are removed by a die.

[0111] S26: drying: the welding wire subjected to the scraping cleaning treatment of step S25 is subjected to drying treatment by using an oven or a hot air circulating drying furnace.

[0112] Comparative Example 2

[0113] A preparation method of a 7xxx aluminum alloy welding wire, comprising the following steps:

[0114] S1: melting and casting an aluminum alloy ingot, the aluminum alloy ingot comprising the following components in mass percentage:

[0115] Zn 7wt%, Mg 2.0wt%, Cu 1.2wt%, Sc 0.2wt%, Zr 0.2wt%, Er 0.1wt%, and the balance being Al;

[0116] Further, step S1 comprises the following specific steps:

[0117] S11: batching: high-purity aluminum and intermediate alloy are batched according to the above-mentioned material atomic component mass percentage. The intermediate alloy includes but is not limited to Al-Zn alloy, Al-Mg alloy, Al-Cu alloy, Al-Sc alloy, Al-Zr alloy, Al-Er alloy.

[0118] S12: melting and casting: the high-purity aluminum is melted (melting temperature is 740℃), the intermediate alloy is separately melted (melting temperature is 760℃), the melt is fully stirred, a refining agent is added, slagging is performed, a degassing agent is added to perform degassing treatment on the melt, the melt is statically kept at about 720℃ for 1h, and the melt is cast into a cast iron mold preheated to 150-250℃ to obtain an ingot.

[0119] S2: the aluminum alloy ingot is subjected to multi-stage homogenization treatment, hot extrusion treatment, solution treatment, cold drawing, first-stage annealing treatment, cold drawing, first-stage annealing treatment, cold drawing, scraping cleaning, and drying.

[0120] Further, the step S2 comprises the following specific steps:

[0121] S21: The multi-stage homogenization treatment: the ingot in step S1 is placed in an air furnace and heated and kept at three different temperature stages: the first stage is kept at 250 DEG C for 5h, the second stage is kept at 350 DEG C for 5h, and the third stage is kept at 450 DEG C for 2h.

[0122] S22: The hot extrusion treatment: the ingot after the homogenization in step S21 is kept at a hot extrusion temperature of 410 DEG C for 1.5h, and then hot extruded into a rod with a diameter of 5mm.

[0123] S23: The solution treatment: the rod in step S22 is heated to 470 DEG C and kept for 1.5h.

[0124] S24: Cold drawing and primary annealing treatment: the rod after the solution treatment in step S23 is alternately subjected to cold drawing, primary annealing treatment, cold drawing, primary annealing treatment, cold drawing to obtain a welding wire. The primary annealing treatment: the annealing temperature is 450 DEG C, and the holding time is 7h. The deformation amount between the two primary annealing treatments is 35%.

[0125] S25: Scrubbing and cleaning: the excess lubricant residues, slight oxidation layer and other tiny attachments possibly generated in the drawing process on the surface of the welding wire in step S24 are removed by a die.

[0126] S26: Drying: the welding wire after the scrubbing and cleaning treatment in step S25 is subjected to drying treatment by using an oven or a hot air circulating drying furnace.

[0127] The physical property indexes of the embodiments or the comparative examples and the test methods thereof are as follows:

[0128] (1) Welding wire mechanical property test: the welding wires prepared by using the above embodiments and comparative examples respectively are subjected to mechanical property test, wherein the mechanical property is detected according to the national standard GB / T 228.1-2021 "Metallic materials-tensile testing-Part 1: Method of test at room temperature".

[0129] (2) Tensile strength test of additive sample: the welding wire prepared by each of the above examples and each of the comparative examples was used to prepare an arc additive manufacturing sample. Among them, the wire feeding speed was 8 m / min, the current was 133 A, and the voltage was 18.8 V; the arc additive manufacturing was carried out on a Fronius CMT Advanced 4000R device, and the Tirangle mode was selected during the additive process, the length was set to 2.5 mm, and the rotation angle of the triangular path between adjacent deposited layers was 9°, pure argon was used as the protective gas, and the flow rate was 17 L / min. The obtained additive sample was detected according to the national standard GB / T 228.1-2021 "Metallic materials tensile test Part 1: Room temperature test method" to detect the tensile strength, and the unit was MPa.

[0130] (3) Welded joint strength coefficient test: the welding wire prepared by each of the above examples and each of the comparative examples was used for arc welding, the welding plate size was 200mm*150mm*4mm, the welding was in the form of butt joint, and the welding was carried out on a Fronius CMT Advanced 4000R device. After welding, the tensile property test of the weld was carried out, the tensile test was carried out according to the requirements in GB / T2651-2021 "Welded joint tensile test method", the tensile strength of the weld was measured, the tensile strength of the weld was compared with the tensile strength of the base material, and the joint strength coefficient was calculated, and the unit was %.

[0131] The performance test results of the welding wire prepared by examples 1-3 and comparative examples 1-2 and the welding wire applied to additive samples and arc welding are shown in the following table 1.

[0132] Table 1

[0133]

[0134] The yield strength, tensile strength, elongation and hardness of the high-strength 7xxx aluminum alloy welding wire prepared by the preparation method of the aluminum alloy welding wire are significantly improved, and the forming effect and mechanical properties are more excellent. The tensile strength of the sample obtained by arc additive manufacturing using the high-strength 7xxx aluminum alloy welding wire of the application can reach 500 MPa, the carrying capacity is improved, and the application demand can be met more widely; in addition, the joint strength coefficient of the welded structure obtained by arc welding using the high-strength 7xxx aluminum alloy welding wire of the application is also significantly improved, the fracture resistance of the welded structure is enhanced, the failure risk of the welded structure is reduced, the more severe working condition requirements can be met, and the application scenarios are expanded.

[0135] The above embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be noted that for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, and the present application also intends to include these modifications and improvements.

Claims

1. A method of making an aluminum alloy welding wire, characterized by: The method comprises the following steps: S1: melting and casting an aluminum alloy ingot, wherein the aluminum alloy ingot comprises the following components in mass percentage: Zn 7-8wt%, Mg 2.0-2.3wt%, Cu 1.2-1.8wt%, Sc 0.2-0.3wt%, Zr 0.2-0.3wt%, Er 0.1-0.2wt%, and the balance being Al; S2: performing multi-stage homogenization treatment, hot extrusion treatment, solid solution treatment, cold drawing, three-stage annealing treatment, cold drawing, three-stage annealing treatment, cold drawing, scraping and cleaning, and drying on the aluminum alloy ingot.

2. The method of making an aluminum alloy welding wire of claim 1, wherein: The three-stage annealing treatment in step S2 comprises the following steps: the first-stage annealing temperature is 250-275℃, the holding time is 8-10h; the second-stage annealing temperature is 300-350℃, the holding time is 8-10h; and the third-stage annealing temperature is 375-450℃, the holding time is 5-8h.

3. The method of making an aluminum alloy welding wire of claim 2, wherein: In step S2, the deformation amount between the two three-stage annealing treatments is 30-40%.

4. The method of making an aluminum alloy welding wire of claim 1, wherein: Step S1 comprises the following specific steps: S11: batching: batching high-purity aluminum and intermediate alloy according to the above-mentioned material atomic component mass percentage; S12: melting and casting: melting the high-purity aluminum, respectively adding the intermediate alloy, fully stirring the melt, adding a refining agent, skimming, adding a degassing agent to perform degassing treatment on the melt, standing and holding, and pouring into a preheated cast iron mold to obtain an ingot.

5. The method of making an aluminum alloy welding wire of claim 1, wherein: In step S11, the intermediate alloy includes but is not limited to Al-Zn alloy, Al-Mg alloy, Al-Cu alloy, Al-Sc alloy, Al-Zr alloy, and Al-Er alloy.

6. The method of making an aluminum alloy welding wire of claim 5, wherein: In step S12, the melting temperature of the high-purity aluminum is 720-750℃; the melting temperature of the intermediate alloy is 750-780℃; and the preheating temperature of the cast iron mold is 150-250℃.

7. The method of making an aluminum alloy welding wire of claim 1, wherein: Step S2 comprises the following specific steps: S21: the multi-stage homogenization treatment: placing the ingot in step S1 into an air furnace and heating and holding at three different temperature stages; the first stage is at 250℃ for 5h, the second stage is at 350℃ for 5h, and the third stage is at 420-450℃ for 2h.

8. The method of making an aluminum alloy welding wire of claim 7, wherein: Step S2 further comprises the following specific steps: S22: the hot extrusion treatment: first, holding the ingot after the homogenization in step S21 at a hot extrusion temperature of 400-420℃ for 1-2h, and then performing hot extrusion to form a rod; the diameter of the rod is 5mm; S23: the solid solution treatment: heating the rod in step S22 to 465-475℃ for 1-2h.

9. A high-strength 7xxx aluminum alloy welding wire prepared by the preparation method in any one of claims 1-8.

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