High-toughness light aluminum alloy for ultra-high voltage power transmission line and preparation process of high-toughness light aluminum alloy

Abstract

The invention discloses a high-strength and high-toughness light aluminum alloy for an ultra-high voltage transmission line and a preparation process of the high-strength and high-toughness light aluminum alloy. The high-strength and high-toughness light aluminum alloy comprises the following components in percentage by weight: 11.45% of Zn, 1wt% of Mg, 1.23% of Cu, 0.199% of trace alloy elements and the balance of Al and impurity elements or 2.75% of Zn, 2.95% of Mg, 1.16% of Cu, 0.199% of trace alloy elements and the balance of Al and impurity elements. According to the high-toughness light aluminum alloy for the ultra-high voltage power transmission line and the preparation process of the high-toughness light aluminum alloy, by adjusting the Zn / Mg ratio and the Cu / Mg ratio, it is studied that the strength, plasticity, exfoliation corrosion resistance, intergranular corrosion resistance and hardenability of the aluminum alloy with the two components are integrated to be in the optimal state.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloys, and in particular to a high-strength and tough lightweight aluminum alloy for ultra-high voltage transmission lines and a preparation process thereof. Background Art

[0002] In recent years, with the rapid development of UHV AC and DC construction in my country, the capacity of UHV transmission projects has continued to rise, the cross-section of transmission wires has become larger and larger, and the distance of large spans has also been expanding. In some areas where lines pass through, there are typical meteorological conditions and line load requirements, and the requirements for the tensile strength and low-temperature performance of the connecting fittings are becoming higher and higher. Higher requirements are put forward for the required transmission and distribution line connecting fittings. Therefore, the research and development of high-strength, tough, corrosion-resistant and lightweight alloy products for UHV lines has become a major topic of common concern in the power grid industry.

[0003] At present, the development trend of UHV lines and the trend of the State Grid replacing steel with aluminum for UHV lines have put forward demands for the connection fittings of power transmission and distribution lines. Through high-strength and light-weight aluminum alloy products, in the harsh environment of high cold and high altitude of UHV transmission lines, the product characteristics and parameters can achieve aluminum replacing steel, thereby reducing line wear and load weight, improving overall line safety and environmental protection, and reducing engineering costs. The industrialization of the target product is of great significance to the construction of national UHV lines, breaking through the production technology difficulties of ultra-high strength aluminum alloy parts and filling the gap.

[0004] High-strength aluminum alloy has the characteristics of light weight, high strength, good toughness, corrosion resistance, etc., and has a wide range of applications. The content of aluminum on the earth ranks third. Due to the low density of aluminum (27000kg / m3), which is only one-third of that of steel, by adding appropriate amounts of other alloying elements to metal aluminum, it can have excellent comprehensive properties and can replace some heavy metal materials to achieve the purpose of lightweight. As aircraft continue to develop along the trend of large-scale, the requirements for aluminum alloys are also constantly increasing. Not only do they need to have good strength and toughness, but they also need to have high hardenability, so that the core of the aluminum alloy can also have good mechanical properties. Therefore, further research is needed on the hardenability of aluminum alloys. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a high-strength and tough lightweight aluminum alloy for ultra-high voltage transmission lines and a preparation process thereof, which solves the problems raised by the above-mentioned background technology.

[0006] To achieve the above objectives, the present invention is implemented through the following technical scheme: a high-strength, tough and lightweight aluminum alloy for ultra-high voltage transmission lines, comprising the following components: Zn-11.45wt.%, Mg-1wt.%, Cu-1.23wt.%, trace alloy elements-0.199wt.%, the balance is Al and impurity elements or Zn-2.75wt.%, Mg-2.95wt.%, Cu-1.16wt.%, trace alloy elements-0.199wt.%, the balance is Al and impurity elements.

[0007] Preferably, the impurity elements are Fe and Si, wherein Fe-0.111wt.%, Si-0.0329wt.% or Fe-0.111wt.%, Si-0.0331wt.%.

[0008] A high-strength and tough lightweight aluminum alloy preparation process for ultra-high voltage transmission lines, according to any one of claims 1-2, characterized in that it comprises the following steps: Step 1: Before smelting, the raw materials and slag materials are transported to the interior of the preheating bin in proportion, and then the raw materials and slag materials are preheated; Step 2: When melting aluminum alloy, first heat the electric furnace to 900°C, then add pure Al, Al-Cu alloy, Al-Sr alloy, Al-Zr alloy and slag-making materials into the electric furnace; Step 3: After the raw materials are melted, put the Al-Zr alloy in and keep it warm for half an hour; after the Al-Zr is melted, stir it evenly, lower the temperature to 850°C, and add the Al-Cu alloy and pure Zn; after 15 minutes, stir it evenly after it is melted, add about 90g of C2Cl6 to degas and stir it gently; after 15 minutes, lower the temperature to 800°C, add Mg wrapped in aluminum foil, not close to the crucible wall, and stir it gently for a few turns after melting to make it diffuse evenly and prevent oxidation; after waiting for 20 minutes, add hexachloroethane to degas and stir it gently; Step 4: The exhaust gas discharged after smelting and combustion in the electric furnace is transported to the interior of the preheating bin to preheat the raw materials and slag-making materials, and then the gas passes through the preheating bin into the interior of the exhaust gas treatment equipment; Step 5: After the aluminum alloy composition is qualified, remove the scum, let it stand for 15 minutes, and then pour it into a metal mold to form an aluminum alloy blank; Step 6: subjecting the aluminum alloy blank to solid solution treatment, and then subjecting it to water cooling quenching to solidification, and subjecting the aluminum alloy blank to aging heat treatment after the quenching is completed and the temperature drops to room temperature; Step seven, subjecting the aging heat treated aluminum alloy blank to homogenization annealing, wherein the homogenization annealing temperatures are 400°C for six hours, 420°C for six hours, 440°C for six hours and 460°C for twelve hours, followed by pre-deformation hot pressing of the homogenization annealed aluminum alloy, and then cutting the pre-deformed aluminum alloy blank into strips for rolling.

[0009] Preferably, in step six, the temperature of the aluminum alloy blank solid solution is maintained at 460° C., 470° C., 480° C. and 490° C. in sequence, and each temperature is maintained for two hours.

[0010] Preferably, in step six, the aging heat treatment temperature of the aluminum alloy blank is maintained at 121° C. for five hours and 133° C. for fifteen hours, respectively.

[0011] Preferably, in the step 4, the waste gas discharged after smelting and combustion in the electric furnace is first subjected to dust removal by dust removal equipment before entering the preheating chamber. Beneficial Effects

[0012] The present invention provides a high-strength and light-weight aluminum alloy for ultra-high voltage transmission lines and a preparation process thereof. Compared with the prior art, it has the following beneficial effects: 1. The high-strength and tough lightweight aluminum alloy for ultra-high voltage transmission lines and its preparation process, by adjusting the Zn / Mg ratio and the Cu / Mg ratio, studied that when the composition is Zn-11.45wt.%, Mg-1wt.%, Cu-1.23wt.%, Fe-0.111wt.%, Si-0.0329wt.%, trace alloy elements-0.199wt.% and the balance is Al, and Zn-2.75wt.%, Mg-2.95wt.%, Cu-1.16wt.%, trace alloy elements-0.199wt.%, Fe-0.111wt.%, Si-0.0331wt.%, and the balance is Al and impurity elements, the strength, plasticity, exfoliation corrosion resistance, intergranular corrosion resistance and hardenability of the aluminum alloy are combined in the optimal state.

[0013] 2. The high-strength, tough and lightweight aluminum alloy used for ultra-high voltage transmission lines and its preparation process, by adjusting the temperature and time of solid solution and the temperature and time of aging heat treatment, have been studied to find that the aluminum alloy has the best comprehensive tensile strength and plasticity properties when the solid solution temperature is maintained at 460°C, 470°C, 480°C and 490°C, each temperature is maintained for two hours, and the aging heat treatment temperature is maintained at 121°C for five hours and 133°C for fifteen hours.

[0014] 3 The high-strength and tough lightweight aluminum alloy used for ultra-high voltage transmission lines and its preparation process preheats the raw materials and slag materials by setting a preheating bin and exhaust gas, which not only reduces the temperature difference between the raw materials and slag materials and the electric furnace, and prevents the explosion of cold raw materials and slag materials after entering the electric furnace, but also improves the smelting efficiency and reduces the combustion and heating time of the electric furnace. In addition, since the hot gas discharged from the electric furnace is used to preheat the raw materials and slag materials, the waste heat of the electric furnace exhaust is fully utilized, reducing energy loss, reducing energy consumption, and realizing energy recycling. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is the work flow chart of the present invention. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] See also Figure 1 The present invention provides a technical solution: a high-strength and tough lightweight aluminum alloy for ultra-high voltage transmission lines, comprising the following components: Zn-11.45wt.%, Mg-1wt.%, Cu-1.23wt.%, trace alloy elements-0.199wt.%, the balance is Al and impurity elements or Zn-2.75wt.%, Mg-2.95wt.%, Cu-1.16wt.%, trace alloy elements-0.199wt.%, the balance is Al and impurity elements, the impurity elements are Fe and Si, wherein Fe-0.111wt.%, Si-0.0329wt.% or Fe-0.111wt.%, Si-0.0331wt.%; 1. Through metallographic structure analysis of aluminum alloys after solid solution with different Zn / Mg ratios and Cu / Mg ratios, the optimal Zn / Mg ratio and Cu / Mg ratio that can maximize the inhibition of grain growth in the aluminum alloy are analyzed.

[0018] 2. XRD analysis The parameters of aluminum alloys and pure aluminum with different Zn / Mg ratios and Cu / Mg ratios were made into XRD analysis spectra, and then referred to the Hall-Pech method, and expressed by function 1.1 ( )、( )、( )、( )and The relationship between: (1.1) In the formula, is the position of the highest diffraction peak; is the half-peak width; is the size of the coherent diffraction zone, is the lattice distortion, is the wavelength of the radiation measured by XRD, The value of is 0.15406.

[0019] By calculating the coherent diffraction zone size ( ) and the average lattice strain ( ), the dislocation density can be expressed by the following functional relationship 1.2 ( ) and the relationship between them: (1.2) Where b is the Burgers vector, and the value of Al is 0.286 nm. The effect of dislocation on strength can be described by the following formula 1.3 ( ) and dislocation density (r): (1.3) Calculate the optimal Zn / Mg ratio and Cu / Mg ratio that can maximize the strength of aluminum alloy; Conductivity, hardness and tensile properties experiments were conducted on aluminum alloys with different Zn / Mg ratios and Cu / Mg ratios, and the best Zn / Mg ratio and Cu / Mg ratio that can maximize the comprehensive mechanical properties of aluminum alloys were obtained. The intergranular and exfoliation corrosion resistance tests were conducted on aluminum alloys with different Zn / Mg ratios and Cu / Mg ratios, and the optimal Zn / Mg ratio and Cu / Mg ratio that can maximize the intergranular and exfoliation corrosion resistance of aluminum alloys were obtained. 5. Analysis of cast hardenability. The aluminum alloys with different Zn / Mg ratios and Cu / Mg ratios after melting and casting were subjected to homogenization annealing and solution treatment in turn, and then end quenching tests were performed. The experiment showed that the optimal Zn / Mg ratio and Cu / Mg ratio can maximize the reduction of the sum of the atomic radius and the sum of the atomic volume difference of the aluminum alloy, thereby maximizing the hardenability of the alloy.

[0020] A high-strength and tough lightweight aluminum alloy preparation process for ultra-high voltage transmission lines, according to any one of claims 1-2, characterized in that it comprises the following steps: Step 1: Before smelting, the raw materials and slag materials are transported to the interior of the preheating bin in proportion, and then the raw materials and slag materials are preheated; Step 2: When melting aluminum alloy, first heat the electric furnace to 900°C, then add pure Al, Al-Cu alloy, Al-Sr alloy, Al-Zr alloy and slag-making materials into the electric furnace; Step 3: After the raw materials are melted, put the Al-Zr alloy in and keep it warm for half an hour; after the Al-Zr is melted, stir it evenly, lower the temperature to 850°C, and add the Al-Cu alloy and pure Zn; after 15 minutes, stir it evenly after it is melted, add about 90g of C2Cl6 to degas and stir it gently; after 15 minutes, lower the temperature to 800°C, add Mg wrapped in aluminum foil, not close to the crucible wall, and stir it gently for a few turns after melting to make it diffuse evenly and prevent oxidation; after waiting for 20 minutes, add hexachloroethane to degas and stir it gently; Step 4: The exhaust gas emitted after smelting and burning in the electric furnace is transported to the interior of the preheating bin to preheat the raw materials and slag-making materials, and then the gas passes through the preheating bin into the interior of the exhaust gas treatment equipment. Before the exhaust gas emitted after smelting and burning in the electric furnace enters the interior of the preheating bin, it is first dedusted by the dust removal equipment; Step 5: After the alloy composition is qualified, remove the scum and pour it into a metal mold to form an aluminum alloy blank; Step 6: The aluminum alloy blank is subjected to solid solution treatment, and the solid solution temperature is maintained at 460°C, 470°C, 480°C and 490°C in sequence, and each temperature is maintained for two hours, and then water-cooled quenching is performed to solidify it. After the quenching is completed and the temperature drops to room temperature, the aluminum alloy blank is subjected to aging heat treatment, and the aging heat treatment temperature is maintained at 121°C for five hours and 133°C for fifteen hours in sequence; Step seven, subjecting the aging heat treated aluminum alloy blank to homogenization annealing, wherein the homogenization annealing temperatures are 400°C for six hours, 420°C for six hours, 440°C for six hours and 460°C for twelve hours, followed by pre-deformation hot pressing of the homogenization annealed aluminum alloy, and then cutting the pre-deformed aluminum alloy blank into strips for rolling.

[0021] At the same time, through the above-mentioned metallographic structure analysis, XRD analysis, conductivity, hardness and tensile performance experiments, intergranular and exfoliation corrosion resistance experiments and cast hardenability analysis, aluminum alloys with different solution treatments and aging heat treatments and aluminum alloys extruded, 50% hot pressed and forged in different directions were analyzed and tested, so as to obtain the best solution temperature, the best temperature aging heat treatment and the best extrusion, 50% hot pressing and forging directions to improve the comprehensive performance of aluminum alloys the most.

[0022] Meanwhile, the contents not described in detail in this specification belong to the prior art known to those skilled in the art.

[0023] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions. The sentence "includes an element defined by ... does not exclude the existence of other identical elements in the process, method, article or device including the element".

[0024] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-strength and light-weight aluminum alloy for ultra-high voltage transmission lines, characterized in that: It includes the following components: Zn-11.45wt.%, Mg-1wt.%, Cu-1.23wt.%, trace alloy elements-0.199wt.%, and the balance is Al and impurity elements or Zn-2.75wt.%, Mg-2.95wt.%, Cu-1.16wt.%, trace alloy elements-0.199wt.%, and the balance is Al and impurity elements.

2. The high-strength and tough lightweight aluminum alloy for ultra-high voltage transmission lines and its preparation process according to claim 1, characterized in that: The impurity elements are Fe and Si, wherein Fe-0.111wt.%, Si-0.0329wt.% or Fe-0.111wt.%, Si-0.0331wt.%.

3. A process for preparing a high-strength and tough lightweight aluminum alloy for ultra-high voltage transmission lines, according to any one of claims 1-2, characterized in that: The following steps are involved: Step 1: Before smelting, the raw materials and slag materials are transported to the interior of the preheating bin in proportion, and then the raw materials and slag materials are preheated; Step 2: When melting aluminum alloy, first heat the electric furnace to 900°C, then add pure Al, Al-Cu alloy, Al-Sr alloy, Al-Zr alloy and slag-making material into the electric furnace; Step 3: After the raw materials are melted, put the Al-Zr alloy in and keep it warm for half an hour; after the Al-Zr is melted, stir it evenly, lower the temperature to 850°C, and add the Al-Cu alloy and pure Zn; after 15 minutes, stir it evenly after it is melted, add about 90g of C2Cl6 to degas and stir it gently; after 15 minutes, lower the temperature to 800°C, add Mg wrapped in aluminum foil, not close to the crucible wall, and stir it gently for a few turns after melting to make it diffuse evenly and prevent oxidation; after waiting for 20 minutes, add hexachloroethane to degas and stir it gently; Step 4: The exhaust gas discharged after smelting and combustion in the electric furnace is transported to the interior of the preheating bin to preheat the raw materials and slag-making materials, and then the gas passes through the preheating bin into the interior of the exhaust gas treatment equipment; Step 5: After the aluminum alloy composition is qualified, remove the scum, let it stand for 15 minutes, and then pour it into a metal mold to form an aluminum alloy blank; Step 6: subjecting the aluminum alloy blank to solid solution treatment, and then subjecting it to water cooling quenching to solidification, and subjecting the aluminum alloy blank to aging heat treatment after the quenching is completed and the temperature drops to room temperature; Step seven, subjecting the aging heat treated aluminum alloy blank to homogenization annealing, wherein the homogenization annealing temperatures are 400°C for six hours, 420°C for six hours, 440°C for six hours and 460°C for twelve hours, followed by pre-deformation hot pressing of the homogenization annealed aluminum alloy, and then cutting the pre-deformed aluminum alloy blank into strips for rolling.

4. The process for preparing a high-strength and tough lightweight aluminum alloy for ultra-high voltage transmission lines according to claim 3, characterized in that: In step 6, the temperature of the aluminum alloy blank solid solution is maintained at 460° C., 470° C., 480° C. and 490° C. in sequence, and each temperature is maintained for two hours.

5. A process for preparing a high-strength and tough lightweight aluminum alloy for ultra-high voltage transmission lines according to claim 4, characterized in that: In step 6, the aging heat treatment temperature of the aluminum alloy blank is maintained at 121° C. for five hours and 133° C. for fifteen hours.

6. A process for preparing a high-strength and tough lightweight aluminum alloy for ultra-high voltage transmission lines according to claim 5, characterized in that: In the step 4, the waste gas discharged after smelting and combustion in the electric furnace is firstly dedusted by dust removal equipment before entering the preheating chamber.

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