Al-Mg-Si aluminum alloy wire as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of aluminum alloy, and particularly relates to an Al-Mg-Si aluminum alloy wire and a preparation method and application thereof. The wire comprises the following components in percentage by weight: 0.6 < = x < = 1, 0.5 < = y < = 1, 0 < = n < = 0.2, and 0 < = m < = 0.2, the total content of the impurity elements Fe, V, Mn, Cu, Cr and Zn is less than or equal to 0.41. The preparation method of the wire comprises the steps of aluminum ingot melting, mixed melting with other elements, refining, casting, extrusion drawing, aging treatment and the like. The wire rod is used for preparing a trans-provincial and trans-regional transmission conductor. The aluminum alloy wire has certain tensile strength and high electric conductivity, and an electric conductor can have excellent current-carrying capacity, so that the aluminum alloy wire can be suitable for trans-provincial and trans-regional long-distance power transmission.

Description

Technical Field

[0001] The present invention belongs to the technical field of aluminum alloys, and in particular relates to an Al-Mg-Si aluminum alloy wire and a preparation method and application thereof. Technical Background

[0002] With the rapid growth of my country's economic scale, the demand for energy is becoming more and more vigorous, and the environmental problems caused by energy consumption are becoming increasingly prominent. Therefore, achieving "energy conservation and emission reduction" has become a very arduous task facing the whole society. It is an important measure to build a transmission channel for large-scale wind power and photovoltaic bases and improve the inter-provincial and inter-regional power transmission capacity. Improving the inter-provincial and inter-regional power transmission capacity is a great challenge for overhead transmission lines. Overhead transmission lines are an important part of the national power grid and are necessary carriers for transmitting current from the power generation end to the power receiving end. The distribution of power resources in my country is not balanced. Most of the large coal-fired power bases are concentrated in the central, western and northern parts, while the main power-consuming industrial cities and industrial and commercial centers are concentrated in the eastern coastal areas. The transmission of wind power and photovoltaic bases is also a long distance. Faced with such unbalanced distribution characteristics of power production and consumption, it is necessary to realize the output and supply of electricity through long-distance transmission lines to solve the problem of imbalance in power production and consumption. The energy consumption generated by long-distance transmission cannot be underestimated, so reducing the loss of long-distance transmission is an important measure to achieve energy conservation and environmental protection, which puts great demands on the conductivity, tensile strength and elongation of aluminum alloy conductors.

[0003] Chinese patent CN105568189A discloses a method for preparing an aluminum-magnesium-silicon alloy wire containing a nanophase, wherein the aluminum alloy wire is composed of the following mass percentage components: Si 0.50%, Fe 0.20%, Mg 0.67%, RE (La / Ce) 0.12%, Cu < 0.05%, Mn < 0.03%, Cr < 0.03%, Zn < 0.05%, and the balance is Al. The aluminum alloy wire is a high-strength medium-conductive wire with a tensile strength of 352 MPa, but a conductivity of only 56% IACS.

[0004] Chinese patent CN105088035A discloses a high-conductivity medium-strength non-heat-treated aluminum alloy conductor material and a preparation method. The aluminum alloy conductor is composed of the following mass percentage components: Mg 0.10-0.20wt%, Cu 0.20-0.30wt%, Fe 0.15-0.30wt%, B 0.05-0.10wt%, the inevitable impurity silicon content is less than 0.05%, the total content of impurities titanium, vanadium, chromium, and manganese is less than 0.01%; aluminum is the remainder. The tensile strength of the aluminum alloy conductor material is ≥240MPa, the conductivity is ≥59.2%IACS, which is lower than 61.9%IACS, and the elongation is only 2.0%.

[0005] Chinese patent CN107267820A discloses an Al-Si-Mg-Fe-Cu conductive alloy rod and a preparation method thereof, wherein the conductive alloy rod has, by mass percentage, Si 3.8-4.0%, Mg 0.5-0.8%, Fe 0.1-0.3%, Cu 0.08-0.1%, B 0.05-0.1%, Sr 0.01-0.04%, and the remainder is Al. The room temperature ultimate tensile strength is ≥350MPa, the elongation is ≥10%, and the conductivity is ≥60%IACS.

[0006] Chinese patent CN115948684B discloses a high-strength and high-conductivity aluminum alloy wire and its manufacturing method. The aluminum alloy wire is composed of the following components in mass percentage: Si 0.68-0.78%, Mg 0.65-0.75%, Cu 0.15-0.25%, Mn 0.05-0.15%, Cr 0.05-0.15%, Fe 0.1-0.2%, the remainder is Al and inevitable impurities, the mass ratio of Si to Mg is: Si≥Mg / 1.73+0.3, the sum of the mass percentages of Mn and Cr is: Mn+Cr≤0.2%. The tensile strength of the aluminum alloy wire of the invention is ≥340MPa, the yield strength is ≥305MPa, and the elongation after fracture is ≥8%, but the conductivity is only 55%IACS.

[0007] It can be seen that due to the mutual restriction between conductivity and strength, the existing aluminum alloy wire manufacturing technology is difficult to take into account the improvement of conductivity and strength. Increasing the strength of the aluminum alloy wire will inevitably sacrifice part of the conductivity. Summary of the invention

[0008] In view of the above problems, the present invention provides an Al-Mg-Si aluminum alloy wire, which has a certain tensile strength and a high electrical conductivity, so that the conductor has excellent current carrying capacity, thereby being suitable for long-distance power transmission across provinces and regions.

[0009] To achieve the above object, the present invention adopts the following technical solution:

[0010] An Al-Mg-Si aluminum alloy wire material, wherein the composition of the wire material is Al-xMg-ySi-nB-mLa, measured by weight percentage, wherein 0.6≤x≤1.0, 0.5≤y≤1.0, 0≤n≤0.2, 0≤m≤0.2; the sum of the contents of impurity elements Fe, V, Mn, Cu, Cr, and Zn is ≤0.41, and the balance is aluminum.

[0011] Preferably, the aluminum alloy wire has a conductivity of ≥58.5% IACS, an ultimate tensile strength at room temperature of ≥103.3 MPa, and an elongation of ≥11.2%.

[0012] Another object of the present invention is to provide a method for preparing the Al-Mg-Si aluminum alloy wire, comprising the following steps:

[0013] S1. After the aluminum ingot is melted, other alloying elements except boron and lanthanum are added to the ingot and mixed and melted thoroughly;

[0014] S2. Add a boron source to the melt of step S1, mix and melt thoroughly;

[0015] S3. Adding a lanthanum source to the melt of step S2, mixing and melting thoroughly;

[0016] S4. Add a refining agent to the melt of step S3, mix thoroughly, perform slag removal, and then keep warm to obtain a molten alloy;

[0017] S5. The alloy melt of step S4 is cast into a mold to obtain an aluminum rod;

[0018] S6. The aluminum rod of step S5 is subjected to extrusion, drawing, aging and cooling to obtain Al-Mg-Si aluminum alloy wire.

[0019] Preferably, in step S1, the insulation temperature is 720°C to 750°C.

[0020] Preferably, in steps S1 to S3, stirring is used for sufficient mixing, and the stirring time is 5 to 10 minutes.

[0021] Preferably, in step S4, the refining uses hexachloroethane as a refining agent, and the amount of hexachloroethane added is 0.5-1% of the weight of the melt.

[0022] Preferably, the refining agent is fully mixed by stirring, and the stirring time is 3 to 5 minutes.

[0023] Preferably, in step S4, the insulation temperature is 720° C. to 750° C., and the insulation time is 10 to 20 minutes.

[0024] Preferably, in step S5, the temperature of the mold is 180-220°C.

[0025] Preferably, in step S6, the temperature of extrusion drawing is room temperature.

[0026] Preferably, in step S6, the aging temperature is 300-400° C., and the aging time is 8-12 hours.

[0027] Preferably, the aluminum ingot is AA1070Al, the boron source is Al-3B master alloy, and the lanthanum source is Al-La master alloy. Pure lanthanum alloy can also be used.

[0028] Another object of the present invention is to provide an application of the high-conductivity medium-strength aluminum alloy wire in the preparation of inter-provincial and inter-regional power transmission wires.

[0029] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0030] 1. The aluminum alloy wire of the present invention contains rare earth lanthanum, which can react with hydrogen and impurity elements in the melt to form compounds, thereby reducing the content of hydrogen and impurity elements in the aluminum melt and improving the mechanical properties and electrical conductivity of the material; rare earth lanthanum can also play a role in refining the matrix grains, thereby increasing the mechanical properties of the material; La element can be adsorbed on Al 13 The growth edge of Fe4 phase prevents Al 13 Fe4 grows and transforms it into spherical or nearly spherical compounds, thereby improving the mechanical properties of the alloy.

[0031] 2. The aluminum alloy wire of the present invention contains boron, which can react with impurity elements such as transition elements Cr, Ti, V, Mn in the aluminum alloy to form borides (Cr, Ti, V, Mn) B2. These borides have a large density and fall to the bottom of the melt after a long period of heat preservation. They remain at the bottom of the crucible during casting, achieving the purpose of purifying the matrix, thereby reducing the scattering effect of lattice distortion caused by impurity elements on electrons and improving the electrical conductivity of the alloy.

[0032] 3. The Si content in the raw material of the present invention is increased, and the excess Si element is precipitated in the form of single crystal Si, which increases the relative dislocation entanglement of the precipitation and improves the electrical conductivity and tensile strength.

[0033] 4. The cold extrusion and cold drawing steps in the preparation method of the aluminum alloy wire of the present invention can make the grains elongate in the stretching direction, reduce the scattering of electrons by the grain boundaries per unit length, and thus improve the conductivity; the obtained wire is subjected to aging treatment, and the distortion energy can accelerate the precipitation of Mg and Si elements from the α-Al matrix, and evenly distribute them in the form of Mg2Si nanoscale secondary phases at the grain boundaries and inside the grains, reducing the scattering of electrons by lattice distortion. Under the premise of ensuring a certain tensile strength, this preparation method develops the limit of the conductivity of the aluminum alloy wire to improve the current carrying capacity of the conductor, so that it can be suitable for long-distance power transmission across provinces and regions.

[0034] In summary, the Al-Mg-Si aluminum alloy of the present invention uses AA1070Al and aluminum-based alloy as raw materials, and rare earth elements lanthanum and boron are added for modification, which can purify the matrix, improve the organizational morphology, reduce the transition elements (Cr, Ti, V, Mn) introduced into the aluminum source and dissolve into the aluminum matrix to cause lattice distortion and electron scattering, and modify the Fe-rich phase morphology in the aluminum source to reduce stress concentration; through extrusion, drawing and aging processing, the strength and conductivity of the alloy can be improved at the same time. The wire has a good application prospect in the preparation of inter-provincial and inter-regional long-distance transmission wires. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The present invention is a process flow chart of the method for preparing the aluminum alloy wire.

[0036] Figure 2 This is a field emission scanning electron microscope image of the high-conductivity medium-strength alloy processed 9 in Example 1 of the present invention.

[0037] Figure 3 It is a schematic diagram of the electrical conductivity of aluminum alloy wires treated 1 to 18 and compared 1 to 6 in Examples 1 and 2 of the present invention.

[0038] Figure 4 It is a schematic diagram of the tensile strength and elongation of aluminum alloy wires in treatments 1 to 18 and comparisons 1 to 6 in Examples 1 and 2 of the present invention. DETAILED DESCRIPTION

[0039] In order to better present the present invention, it is illustrated by specific implementation cases, which belong to the protection scope of the present invention but do not limit the protection scope of the present invention.

[0040] Example 1

[0041] A method for preparing Al-Mg-Si aluminum alloy wire, using industrial pure aluminum ingots with a purity greater than 99.7% (wherein Si is less than 2.5×10 -3 %), Al-10%Mg master alloy, Al-10%Si master alloy as raw materials, comprising the following steps:

[0042] S1. Put the industrial pure aluminum ingot into the furnace to melt, keep the alloy liquid at 720℃~750℃, add other alloy elements except boron and lanthanum, and stir for 5~10min to make it fully mixed and melted;

[0043] S2. Add Al-3B master alloy to the melt of step S2 and stir for 5 to 10 minutes to fully mix and melt;

[0044] S3. Add Al-La master alloy to the melt of step S3 and stir for 5 to 10 minutes to fully mix and melt;

[0045] S4. Adding 0.5-1% of the weight of the melt as a refining agent hexachloroethane to the melt of step S4, stirring for 3-5 minutes to fully mix and refine, and then performing a slag removal treatment, wherein the slag or inclusions are allowed to float to the surface of the aluminum alloy melt, and the slag on the surface of the melt is removed; after the slag removal treatment, the slag is kept at 720°C to 750°C for 10-20 minutes to obtain an alloy melt;

[0046] S5. The alloy melt of step S4 is cast into a preheated graphite mold at a preheating temperature of 180 to 220°C to obtain a round aluminum rod with a diameter of 12 mm;

[0047] S6. The aluminum rod of step S5 is extruded and drawn at room temperature to obtain an aluminum wire with a diameter of 2 mm and a total deformation of 97.2%; the aluminum wire is aged at 300-400° C. for 8-12 h, and then cooled to room temperature in the furnace to obtain an Al-Mg-Si aluminum alloy wire.

[0048] Measured by weight percentage, the composition of the wire is Al-xMg-ySi-nB-mLa, wherein 0.6≤x≤1.0, 0.5≤y≤1.0, 0≤n≤0.2, 0≤m≤0.2; the sum of the contents of impurity elements Fe, V, Mn, Cu, Cr, and Zn is ≤0.41, and the balance is aluminum.

[0049] In this embodiment, different treatment groups (as shown in Table 1) are set with the mass percentage of each element as a variable to investigate the effects of different element contents on the electrical conductivity and strength properties of the aluminum material.

[0050] Table 1

[0051]

[0052]

[0053] Example 2

[0054] This embodiment is based on the preparation method of Example 1 and further based on treatment 9, with aging temperature and aging time as variables, setting different treatment groups (as shown in Table 2) to investigate the effects of different process parameters on the conductivity and strength properties of aluminum materials.

[0055] Table 2

[0056]

[0057] Example 3 Performance Test

[0058] 1. Use QJ84 digital DC double-arm bridge to test the conductivity of each treated and compared wire.

[0059] 2. The tensile strength and elongation of each treated and compared wire were tested using a Chinese AGS-X 100KN universal testing machine.

[0060] 3. Test results are shown in Table 3

[0061] Table 3

[0062] Treatment Group Electrical conductivity / IACS% Tensile strength / MPa Elongation / % Process 1 58.5 103.6 16 Process 2 58.8 109.6 17.2 Process 3 59.1 114.2 19 Process 4 58.9 103.3 17 Process 5 59.9 107.3 21.6 Process 6 60.5 111.6 16.2 Process 7 59.5 108.4 18 Process 8 60.8 117.6 19.2 Process 9 61.8 128.2 18 Processing 10 60.2 134.6 17.8 Process 11 61.1 109.4 13.8 Processing 12 60.8 116.2 12.7 Process 13 60.9 114.2 11.2 Processing 14 59.2 130.6 16.6 Processing 15 60.8 129.8 17 Processing 16 61.2 129 17.4 Processing 17 61.0 122.4 16.8 Processing 18 60.8 124.6 17.2 Comparison 1 62.1 89 17.8 Comparison 2 60.1 131 10.1 Contrast 3 60.8 118.2 15.3 Contrast 4 59.8 113.4 8.2 Contrast 5 60.5 130.2 11.2 Contrast 6 60.8 110.2 17

[0063] It can be seen from Table 3 that among treatments 1 to 15, the conductivity of the aluminum alloy wire prepared by treatment 9 of the present invention reaches 61.8% IACS, the tensile strength is greater than 128.2 MPa, and the elongation reaches 18%. Treatment 9 has excellent mechanical and electrical properties. In terms of composition, the Si residual type 6 series alloy can ensure the precipitation amount of Mg element during the aging process, greatly reduce the influence of solid solution elements on conductivity, and compensate for the tensile strength by precipitation strengthening.

[0064] From the comparison between treatment 1 and the first-stage treatment (treatment 2, treatment 4, treatment 5) or the second-stage treatment (treatment 3, treatment 7, treatment 9), it can be seen that treatment 1 did not add B and La elements, and the properties of the products were at a low level; treatments 2, 3 or 4, 7 added one of the B and La elements, and the conductivity and elongation of the products were improved to a certain extent, but compared with treatment 5 or 9 where B and La elements were added at the same time, the conductivity and elongation were still lower. This is because the B element can react with impurity elements such as transition elements Cr, Ti, V, Mn and other impurity elements in the matrix to form borides (Cr, Ti, V, Mn) B2. These borides have a large density and fall to the bottom of the melt after a long heat preservation. They remain at the bottom of the crucible during casting, achieving the purpose of purifying the matrix, thereby reducing the scattering effect of lattice distortion caused by impurity elements on electrons and improving the conductivity of the alloy. The La element can reduce the content of hydrogen and other impurity elements in the matrix; the La element also plays a role in refining the grains and adsorbing on the growth edge of the Al13Fe4 phase to prevent Al 13 Fe4 grows and transforms it into spherical or nearly spherical compounds, thereby improving the mechanical properties of the alloy. In principle, B impurity removal and La modification both play a role in purifying the matrix. The La element also plays a role in refining the grains and modifying the morphology of the aluminum-iron phase, so it plays an enhancing role in improving the mechanical and electrical properties. The effect of the second-stage treatment is also higher than that of the first-stage treatment. This is because, with the increase in the amount of B and La elements, the purification of the matrix, the refinement of the grains, and the modification of the aluminum-iron phase morphology are enhanced, and the optimal content is reached at the treatment of 9.

[0065] From the comparison of treatment 6, treatment 9 and treatment 10, it can be seen that on the basis of the same content of Mg, Si and La elements, the B content of treatment 6 is low, and the conductivity, tensile strength and elongation of the product are all reduced; the B content of treatment 10 is high, the conductivity and elongation of the product are reduced, and the tensile strength is increased. This is because when the B content is too low, the impurity removal effect is reduced, and a certain amount of transition elements still exist in the matrix, causing lattice distortion and affecting both conductivity and elongation; when the B content is too high, the radius of the B atom is smaller than that of the Al atom, and the integrity of the Al lattice is destroyed in the form of interstitial atoms, thereby reducing the transmission efficiency of electrons to a certain extent, which is harmful to electron transmission, and lattice distortion improves tensile strength.

[0066] From the comparison of treatment 8, treatment 9 and treatment 11, it can be seen that on the basis of the same content of Mg, Si and B elements, the La content of treatment 8 is low, the conductivity and tensile strength of the product decrease, and the elongation increases; the La content of treatment 11 is high, and the conductivity, tensile strength and elongation of the product all decrease. This is because when the La element is in an appropriate amount, it is distributed at the edge of the aluminum-iron phase and plays a role in modifying the morphology; when the La element is insufficient, the iron phase reduces the continuity of the matrix, causing the conductivity and tensile strength to decrease; when the La element is too high, it exists in the matrix in the form of impurities, causing the conductivity, tensile strength and elongation to decrease at the same time.

[0067] From the comparison of treatment 9, treatment 14, treatment 15 and comparison 1, it can be seen that on the basis of the same content of other elements, the Si content of treatment 14 and treatment 15 is higher, and the conductivity, tensile strength and elongation of the product are all on a downward trend; the Si content of comparison 1 is low, the mechanical properties are improved, but the loss of tensile strength is too serious (the conductivity and elongation of the product are improved, and the tensile strength is seriously reduced). This is because the damage of solute atoms to conductivity is much greater than that of precipitation. When the silicon content is too low, the Mg and Si solid solution atoms in the product precipitate in the form of Mg2Si phase, which greatly improves the conductivity, but the precipitation strengthening effect is limited, and the tensile strength is low; when the silicon content is moderate, the excess Si atoms are evenly distributed in the matrix in the form of single crystal Si, compensating for the loss of strength, so as to obtain products with improved mechanical and electrical properties at the same time; when the silicon content is too high, the excess Si atoms exist in the form of eutectic silicon, which reduces the continuity of the matrix and has an adverse effect on the performance.

[0068] From the comparison of treatments 16 to 18 and comparisons 2 to 5, it can be seen that the aging temperature and time also have a certain influence on the performance of the product. In comparison 2, the aging time is insufficient. On the basis of the same Si content, the amount of precipitated phase is relatively small, the scattering of electrons is increased, and the conductivity and elongation are low; in comparison 3, the aging time is long. On the basis of the same B element content, the excess B element is dissolved into the matrix, the degree of lattice distortion is increased, and the electrical properties are adversely affected; in comparison 4, due to the insufficient aging temperature, the strengthening effect of the conductor precipitation phase is weakened, and the solid solution elements have a great influence on the conductivity, resulting in extremely low elongation; in comparison 5, due to the excessively high temperature setting, the Mg2Si precipitation phase will dissolve back.

[0069] From the comparison between treatment 18 and comparison 6, it can be seen that the performance of the product of the present invention is better than that of conventional hot extrusion when mechanical processing is performed at room temperature. This is because cold extrusion and cold drawing at room temperature can make the grains elongate in the stretching direction, reduce the scattering of electrons by the grain boundary per unit length, and thus improve the conductivity. Combined with simple aging treatment, the overall performance of the product is better than that of conventional hot extrusion.

[0070] The above contents are further detailed descriptions of the present invention in combination with specific / preferred implementations, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, they can also make several substitutions or modifications to these described embodiments without departing from the concept of the present invention, and these substitutions or modifications should be regarded as belonging to the protection scope of the present invention.

Claims

1. An Al-Mg-Si aluminum alloy wire, characterized in that: Measured by weight percentage, the composition of the wire is Al-xMg-ySi-nB-mLa, wherein 0.6≤x≤1, 0.5≤y≤1, 0≤n≤0.2, 0≤m≤0.2; the sum of the contents of impurity elements Fe, V, Mn, Cu, Cr, and Zn is ≤0.41, and the remainder is aluminum.

2. The Al-Mg-Si aluminum alloy wire according to claim 1, characterized in that: The electrical conductivity of the aluminum alloy wire is ≥58.5% IACS, the ultimate tensile strength at room temperature is ≥103.3 MPa, and the elongation is ≥11.2%.

3. A method for preparing an Al-Mg-Si aluminum alloy wire according to claim 1 or 2, characterized in that: The following steps are involved: S1. After the aluminum ingot is melted, it is kept warm, and other alloy elements except boron and lanthanum are added, and the mixture is fully mixed and melted; S2. Add a boron source to the melt of step S1, mix and melt thoroughly; S3. Adding a lanthanum source to the melt of step S2, mixing and melting thoroughly; S4. The melt of step S3 is refined, slag-pulled and then kept warm to obtain a molten alloy; S5. The alloy melt of step S4 is cast into a mold to obtain an aluminum rod; S6. The aluminum rod of step S5 is subjected to extrusion, drawing and aging treatment to obtain Al-Mg-Si aluminum alloy wire.

4. The method for preparing the Al-Mg-Si aluminum alloy wire according to claim 3, characterized in that: In step S1, the insulation temperature is 720°C to 750°C.

5. The method for preparing the Al-Mg-Si aluminum alloy wire according to claim 3, characterized in that: In step S4, the insulation temperature is 720° C. to 750° C., and the insulation time is 10 to 20 minutes.

6. The method for preparing the Al-Mg-Si aluminum alloy wire according to claim 3, characterized in that: In step S5, the temperature of the mold is 180-220°C.

7. The method for preparing the Al-Mg-Si aluminum alloy wire according to claim 3, characterized in that: In step S6, the temperature of the extrusion drawing is room temperature.

8. The method for preparing the Al-Mg-Si aluminum alloy wire according to claim 3, characterized in that: In step S6, the aging temperature is 300-400° C. and the aging time is 8-12 hours.

9. The method for preparing an Al-Mg-Si aluminum alloy wire according to any one of claims 3 to 8, characterized in that: The aluminum ingot is AA1070Al; the boron source is Al-3B master alloy; and the lanthanum source is pure metal lanthanum or Al-La master alloy.

10. Use of the high-conductivity medium-strength aluminum alloy wire as claimed in claim 1 or 2 in the preparation of inter-provincial and inter-regional power transmission wires.

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