A high conductivity cast aluminum alloy material and its preparation method and application

Abstract

The invention discloses a high-conductivity cast aluminum alloy material and a preparation method and application thereof. The high-conductivity cast aluminum alloy material of the invention is composed of the following percentage components: Si: 0.6-1.6wt%, Mg: 0.34-0.63wt%, Zn: 0.09-0.13wt%, Cu: 0.11-0.16wt%, Fe: 0.09-0.13wt%, B: 0.04-0.06wt%, Sr: 0.03-0.05wt%, Mn: 0.03-0.04wt%, Cr: 0.03-0.04wt%, and the rest is Al and other inevitable impurities. The cast aluminum alloy of the invention has high conductivity and yield strength, and can be formed into conductor parts for high-voltage switches by ordinary gravity casting process. The forming effect, production cost, etc. are no different from those of traditional ZL101A, and have higher conductivity than ZL101A.

Description

Technical Field

[0001] The invention relates to a high-conductivity cast aluminum alloy material and a preparation method and application thereof, belonging to the technical field of aluminum alloy preparation and processing. Background Art

[0002] With the rapid growth of power supply capacity and electricity demand, the increasing tension of resources and energy, and the increasing efforts in environmental protection, it is necessary to further improve the transmission capacity of the power system. This problem is more prominent especially in economically developed areas. On the electricity consumption side, the current capacity of high-voltage switchgear of various voltage levels can no longer meet the requirements of the growing electricity load, and the capacity needs to be increased urgently.

[0003] Cast aluminum alloys are cheap, have isotropic structures, good casting properties, can be produced in small batches or in large batches, and have become the most widely used and applied type of alloys. In high-voltage switch products, a large number of aluminum alloy conductive or electrical connection parts with complex structures are often cast and formed using ZL101A aluminum alloy with low cost and conductivity. This cast alloy has good casting properties, low cost, low elastic coefficient, isotropic structure, has medium-strength mechanical properties, and is suitable for mass production. However, the conductivity of ZL101A aluminum alloy has not been significantly improved, and it is difficult to meet the development needs of high-voltage switch capacity increase, miniaturization, and high conductivity. With the development of high-voltage switch products, conductive casting parts face the dilemma of reduced structural size. The use of existing cast aluminum alloys will inevitably cause engineering problems such as excessive temperature rise and low strength, which seriously affects the safe and reliable operation of the product. Therefore, it is urgent to study the performance and preparation of high-conductivity cast aluminum alloys to solve the problem of low conductivity of the existing ZL101A, and provide technical support for the large capacity, miniaturization and reliable operation of high-voltage switch equipment.

[0004] At present, China has a certain research foundation in high-conductivity aluminum alloys, but it mainly focuses on aluminum alloy wires, and has achieved certain technical and application results; in terms of cast aluminum alloys for high-voltage switches, ZL101A cast aluminum alloy materials are currently mainly used, and the casting process is relatively mature; there is a certain research foundation at home and abroad in casting with high-conductivity aluminum alloys with low alloy components, but it mainly focuses on the casting molding of simple structural parts. There is still a blank in the use of high-conductivity aluminum alloy casting for switch product components with complex spatial structures. Summary of the invention

[0005] The first object of the present invention is to provide a high conductivity cast aluminum alloy material so as to solve the problem of insufficient conductivity of the existing ZL101A aluminum alloy conductor component for high voltage switches.

[0006] The second object of the present invention is to provide a method for preparing a high conductivity cast aluminum alloy material.

[0007] The third object of the present invention is to provide the use of high conductivity cast aluminum alloy material in the preparation of conductor devices for high voltage switches.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] A high-conductivity cast aluminum alloy material, which consists of the following components in percentage: Si: 0.6-1.6wt%, Mg: 0.34-0.63wt%, Zn: 0.09-0.13wt%, Cu: 0.11-0.16wt%, Fe: 0.09-0.13wt%, B: 0.04-0.06wt%, Sr: 0.03-0.05wt%, Mn: 0.03-0.04wt%, Cr: 0.03-0.04wt%, and the rest is Al and other inevitable impurities.

[0010] The present invention fully considers the performance of the high-conductivity aluminum alloy itself and the role of each alloying element, and regulates the composition of the aluminum alloy as a whole, and regulates the alloying element Si. Under the condition of minimizing the damage to the conductive properties of the casting, the castability and thermal cracking resistance of the alloy are improved by appropriately increasing the Si content, and at the same time, suitable trace elements such as Cu and Mg are added to form stable, fine and dispersed intermetallic compounds, thereby improving the mechanical properties of the alloy to achieve high conductivity and good mechanical strength. In addition, the casting process and heat treatment process are studied and analyzed, and the mechanical properties and conductivity of the casting are further improved through a suitable heat treatment process.

[0011] Specifically, the high-conductivity cast aluminum alloy of the present invention mainly adds alloy elements such as Si, Mg, Zn, and Cu. Si is limited to between 0.6wt% and 1.6wt%. By increasing the content of silicon, the aluminum-silicon alloy has basic fluidity and reduces the volume shrinkage during solidification, improves casting performance and corrosion resistance, reduces the tendency of hot cracks in castings, and increases the heat treatment strengthening effect. At the same time, the Si content is controlled to meet the high conductivity requirements. The appropriate addition of Mg, Zn, and Cu elements is to improve the strength of the material to meet the use requirements of the mechanical properties of conductor castings, and the Mg+Zn+Cu content should not be too high to avoid a decrease in conductivity. Magnesium is limited to 0.34-0.63wt%. On the one hand, magnesium plays a role in solid solution strengthening. On the other hand, magnesium can form Mg2Si phase with silicon. In the heat treatment state, Mg2Si dissolves in the solid solution and precipitates in the subsequent aging process, which plays a precipitation strengthening role and further improves the tensile strength and yield strength. Copper is limited to 0.11-0.16wt%. Adding copper can refine the grains, improve the tensile strength and fatigue strength of the alloy, improve the machinability of the alloy and improve the surface finish. Boron can strengthen the crystal core and refine the grains, but if excessive boron is added, the second phase formed will increase, there will be too much migration focus, which will significantly reduce the conductivity. Therefore, the boron is controlled at 0.04-0.06wt%, and the final strength is significantly improved, but good conductivity can still be maintained. Chromium is controlled at 0.03-0.04wt%, which forms intermetallic compounds in aluminum, hinders the nucleation and growth process of recrystallization, and can improve the toughness of the alloy. Manganese is controlled at 0.03-0.04wt%, and iron is controlled at 0.9-0.13wt%. Microalloying of manganese can improve strength and change the microscopic phase of iron, changing the original needle-like form of iron into a block, neutralizing the harmful effects of iron, thereby improving the elongation and conductivity of the alloy at the same time. In addition, manganese will significantly increase the resistance of aluminum, so the content of Mn should be strictly controlled when used as a conductive material. Aluminum-strontium master alloy is used as a modifier, and strontium is added to refine the grains. Sr can preferentially combine with elements such as Si, Fe, and Cu to form dispersion strengthening, reducing the solid solubility of these elements in the alloy, thereby improving the alloy strengthening effect and conductive properties.

[0012] More specifically, the sum of other inevitable impurities is no more than 0.1 wt %.

[0013] A method for preparing a high conductivity cast aluminum alloy material comprises the following steps:

[0014] S1: Put the raw materials into the melting furnace, evacuate and fill with protective gas, heat up to 740-750℃ to melt the raw materials, cool down to 715-725℃, stir evenly, add the modifier Al-Sr master alloy and refining agent, keep the temperature and let it stand for a while before slagging;

[0015] S2: Control the temperature of the aluminum alloy melt after slagging in step S2 to 720-730° C. before pouring into the mold;

[0016] S3: The casting obtained in S3 is subjected to heat treatment, wherein the heat treatment includes solution treatment and aging treatment.

[0017] The preparation method of the high-conductivity cast aluminum alloy material of the present invention is simple and highly operable. The alloy sample after casting is subjected to heat treatment (solid solution + aging treatment) to further improve the comprehensive mechanical properties and conductive properties of the alloy.

[0018] Specifically, by changing the morphology of the silicon phase in the alloy and refining the alloy's grains, improving the alloy's microstructure and mechanical properties, and on this basis rationally optimizing the alloy element ratio and heat treatment process, we ultimately developed a high-conductivity cast aluminum alloy conductive material to replace the ZL101A aluminum alloy.

[0019] More specifically, the Al, Mg and Zn are selected from industrial pure aluminum, pure magnesium and pure zinc respectively; the Cu, Fe, B, Sr, Cr and Mn are selected from Al-50Cu master alloy, Al-20Fe master alloy, Al-B master alloy, Al-Sr master alloy, Al-Cr master alloy and Al-Mn master alloy respectively.

[0020] Preferably, the solution treatment temperature in step S3 is 520-530° C., the duration is 5-6 hours, and the cooling method is water cooling.

[0021] Specifically, the solution treatment temperature and time have a great influence on the mechanical properties of the alloy. If the temperature is too high, the casting will be overburned, and if the time is too long, the silicon phase may be abnormally coarse; if the temperature is too low and the time is too short, the solution is insufficient. The present invention heats the casting alloy to 520-530°C and maintains it for 5-6 hours, which can achieve the redissolution of the alloy precipitation phase, the homogenization of the casting, and the granulation of the eutectic silicon.

[0022] Preferably, the temperature of the aging treatment in step S3 is 190-200° C., the duration is 5-6 hours, and the cooling method is air cooling.

[0023] Specifically, after solution treatment, the alloy is subjected to aging treatment under the above conditions, so that the dispersed strengthening phase can be precipitated from the matrix and evenly distributed inside the alloy. The strengthening phase will cause the stress-strain field in the alloy to change, thereby hindering the movement of mobile dislocations inside the grains or at the grain boundaries, further improving the strength of the alloy, and the alloy has better comprehensive mechanical properties. The Al-Si-Mg based alloy of the present invention mainly generates Mg2Si strengthening phase during artificial aging, thereby achieving the purpose of improving the strength of the alloy.

[0024] Preferably, the protective gas in step S1 is argon.

[0025] Argon is very inactive and cannot burn, but it can remove dissolved hydrogen and other particles in molten aluminum, providing good conditions for the casting of aluminum alloys.

[0026] Preferably, the heat preservation and standing time in step S1 is 15 to 20 minutes.

[0027] Preferably, the mold in step S2 is preheated to 275-285° C. before pouring, and a release agent is sprayed.

[0028] Application of high conductivity cast aluminum alloy materials in the preparation of conductor devices for high voltage switches.

[0029] The cast aluminum alloy of the present invention has high electrical conductivity and yield strength, and can be formed into conductor parts for high-voltage switches through a common gravity casting process. The forming effect and production cost are the same as those of the traditional ZL101A. Compared with ZL101A, the cast aluminum alloy has higher electrical conductivity.

[0030] Beneficial effects of the present invention:

[0031] 1. The cast aluminum alloy of the present invention has high electrical conductivity and yield strength. The electrical conductivity in the cast state can reach more than 47% IACS, and the electrical conductivity can reach 50% IACS-53% IACS% after T6 heat treatment. The hardness is ≥70HB, the tensile strength is ≥240MPa, the yield strength is ≥240MPa, and the elongation is ≥1%.

[0032] 2. The preparation method of the present invention can obtain a high-conductivity cast aluminum alloy, and the obtained aluminum alloy has good thermal cracking resistance, good fluidity and other process characteristics, and can be formed into conductor parts for high-voltage switches through ordinary gravity casting process. The molding effect and production cost are the same as those of traditional ZL101A. Compared with ZL101A, it has higher conductivity; and the preparation method is simple and easy to control. The present invention also reduces the occurrence of casting thermal cracking by accurately controlling the Si content of the alloy, thereby improving the casting yield rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A conductor device for a high-voltage switch in Embodiment 8 of the present invention;

[0034] Figure 2 This is a metallographic diagram of a 0.6% Si aluminum alloy prepared in Example 1 of Experimental Example 1 of the present invention;

[0035] Figure 3 This is the metallographic phase diagram of the 0.6% Si aluminum alloy after heat treatment prepared in Example 1 of Experimental Example 2 of the present invention. DETAILED DESCRIPTION

[0036] The present invention is further described in conjunction with specific implementation modes, but the protection scope of the present invention is not limited thereto:

[0037] 1. Specific embodiment of a high conductivity cast aluminum alloy material

[0038] The present invention improves the castability and thermal cracking resistance of the alloy by appropriately increasing the Si content in the aluminum alloy, and at the same time adds appropriate trace elements such as Cu, Mg, and Zn to form stable, fine and dispersed intermetallic compounds to improve the mechanical properties of the alloy, thereby achieving high conductivity and good mechanical strength. The specific implementation operations are as follows:

[0039] Examples 1 to 6

[0040] A high conductivity cast aluminum alloy material of the present invention is composed of the following percentage components: Si: 0.6-1.6wt%, Mg: 0.34-0.63wt%, Zn: 0.09-0.13wt%, Cu: 0.11-0.16wt%, Fe: 0.09-0.13wt%, B: 0.04-0.06wt%, Sr: 0.03-0.05wt%, Mn: 0.03-0.04wt%, Cr: 0.03-0.04wt%, and the rest is Al and other inevitable impurities, and the sum of other inevitable impurities is not more than 0.1wt%. The components of the aluminum alloys of Examples 1-6 are shown in Table 1.

[0041] Table 1 Details of aluminum alloy components in Examples 1 to 6

[0042]

[0043] 2. Specific embodiment of a method for preparing a high conductivity cast aluminum alloy material

[0044] Example 7

[0045] The present embodiment provides a method for preparing a high-conductivity cast aluminum alloy material. The aluminum alloy of Example 1 is prepared. After each component is smelted and poured, it is subjected to heat treatment. The specific implementation operations are as follows:

[0046] 1. Ingredients: According to the set chemical composition, industrial pure aluminum, Al-Si50 master alloy, pure magnesium, pure zinc, Al-50Cu master alloy, Al-20Fe master alloy, Al-B master alloy, Al-Mn master alloy, Al-Cr master alloy and Al-Sr master alloy are weighed in a metering ratio for preparation.

[0047] 2. Melting: Except for Al-Sr master alloy, weighed raw materials are put into a melting furnace, vacuumed and washed, and then filled with high-purity argon as a protective gas. The temperature is raised to 745°C to melt the raw materials to obtain a melt, and the melt is heated to 720°C and stirred evenly. Subsequently, the denaturant Al-Sr master alloy and refining agent (Huazhong Aluminum, HZ-WYJ smokeless refining agent) are added, and the slag is removed after being kept at a temperature of 15 minutes.

[0048] 3. Pouring: Preheat the metal mold to 280℃, spray the mold with release agent before pouring, and control the temperature of the aluminum liquid at 725℃ for pouring.

[0049] 4. Heat treatment: The material obtained in step 3 is subjected to T6 heat treatment, which includes solution treatment and aging treatment. First, the alloy is kept at 525°C for 5.5 hours, and then the alloy after solution treatment is quenched with water at room temperature. After the quenched alloy is kept at 195°C for 5.5 hours, it is air-cooled to obtain a highly conductive cast aluminum alloy material.

[0050] On the basis of this embodiment, in step 4 heat treatment, the temperature of solid solution is 520℃, and it is kept warm for 6 hours or the temperature of solid solution is 530℃, and it is kept warm for 5 hours; in aging treatment, the temperature is 190℃, and it is kept warm for 6 hours or the temperature is 200℃, and it is kept warm for 5 hours. In step 2 smelting, the temperature is raised to 740℃ or 750℃, and the temperature is lowered to 715℃ or 725℃; in step 3 pouring, the metal mold is preheated to 275℃ or 285℃, the aluminum liquid temperature is controlled at 720℃ or 730℃, and it is kept warm for 20 minutes. The prepared high-conductivity cast aluminum alloy material can achieve the technical effect basically consistent with this embodiment.

[0051] Based on this embodiment, the high-conductivity cast aluminum alloy materials in embodiments 2 to 6 can also be prepared according to this method.

[0052] 3. Specific examples of the application of high conductivity cast aluminum alloy materials in the preparation of conductor devices for high voltage switches

[0053] The high-conductivity cast aluminum alloy material of the present invention has high conductivity and yield strength and can be formed into conductor parts for high-voltage switches through ordinary gravity casting process. The forming effect and production cost are the same as those of traditional ZL101A. Compared with ZL101A, it has higher conductivity. The specific implementation operation is as follows:

[0054] Example 8

[0055] The high conductivity cast aluminum alloy material of this embodiment is used in the preparation of a conductor device for a high voltage switch. The alloy formula of Example 1 is used, and the preparation method of Example 7 is used to prepare a conductor device for a high voltage switch after heat treatment, machining and surface polishing. Figure 1 shown.

[0056] 4. Experimental examples of testing the properties of aluminum alloys with different compositions as-cast and after heat treatment

[0057] The high conductivity cast aluminum alloy material of the present invention can achieve a conductivity greater than 47% IACS in the cast state, and can reach 50% IACS-53% IACS% after T6 heat treatment, hardness ≥70HB, tensile strength ≥240MPa, yield strength ≥240MPa, and elongation ≥1%. In addition, the present invention reduces the occurrence of casting hot cracks by accurately controlling the Si content of the alloy, thereby improving the casting yield rate.

[0058] Experimental Example 1

[0059] In this experimental example, the cast properties of aluminum alloys with different compositions in Examples 1 to 6 were tested using "GB-T 1173-1995 Casting Aluminum Alloys - National Standard". The test results are shown in Table 2. The cast metallographic structure of the alloy in Example 1 is shown in Table 2. Figure 2 .

[0060] Table 2 Casting properties of different alloy compositions

[0061]

[0062] Experimental Example 2

[0063] In this experimental example, the casting performance of the aluminum alloys with different compositions in Examples 1 to 6 was tested after heat treatment using "GB-T 1173-1995 Casting Aluminum Alloys - National Standard". The test results are shown in Table 3. The metallographic structure of the alloy in Example 1 after heat treatment is shown in Table 3. Figure 3 .

[0064] Table 3 Properties of castings after heat treatment (T6)

[0065]

[0066] Depend on Figure 2 and Figure 3 It can be seen that after heat treatment, the coarse block eutectic silicon in the alloy is transformed into fine chains and particles, and the existence form of the phase has changed, and the dispersion strengthening phase is more evenly dissolved in the matrix.

[0067] The cast aluminum alloy of the present invention has high electrical conductivity and yield strength. The electrical conductivity in the cast state can reach more than 47% IACS, and the electrical conductivity can reach 50% IACS-53% IACS% after T6 heat treatment. The hardness is ≥70HB, the tensile strength is ≥240MPa, the yield strength is ≥240MPa, and the elongation is ≥1%.

[0068] Finally, it is noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high conductivity cast aluminum alloy material, characterized in that: The aluminum alloy material consists of the following components in percentage: composition: Si: 0.6~1.6wt%, Mg: 0.34~0.63wt%, Zn: 0.09~0.13wt%, Cu: 0.11~0.16wt%, Fe: 0.09~0.13wt%, B: 0.04~0.06wt%, Sr: 0.03~0.05wt%, Mn: 0.03~0.04wt%, Cr: 0.03~0.04wt%, and the rest are Al and other inevitable impurities; the preparation method of the high conductivity cast aluminum alloy material comprises the following steps: S1: Put the raw materials into the melting furnace, evacuate and fill with protective gas, heat up to 740~750℃ to melt the raw materials, cool down to 715~725℃, stir evenly, add the modifier Al-Sr master alloy and refining agent, keep the temperature and let it stand for a while before slagging; S2: Control the temperature of the aluminum alloy melt after slagging in step S1 to 720-730°C before pouring into the mold; S3: heat treating the casting obtained in S2, wherein the heat treatment includes solution treatment and aging treatment; The solution temperature in step S3 is 520-530°C, the duration is 5-6 hours, and the cooling method is water cooling; The aging treatment in step S3 is performed at a temperature of 190-200° C., for a duration of 5-6 hours, and in an air-cooling manner.

2. A method for preparing a high conductivity cast aluminum alloy material as claimed in claim 1, characterized in that: The following steps are involved: S1: Put the raw materials into the melting furnace, evacuate and fill with protective gas, heat up to 740~750℃ to melt the raw materials, cool down to 715~725℃, stir evenly, add the modifier Al-Sr master alloy and refining agent, keep the temperature and let it stand for a while before slagging; S2: Control the temperature of the aluminum alloy melt after slagging in step S1 to 720-730°C before pouring into the mold; S3: The casting obtained in S2 is subjected to heat treatment, wherein the heat treatment includes solution treatment and aging treatment.

3. The method for preparing a high conductivity cast aluminum alloy material according to claim 2, characterized in that: The solution temperature in step S3 is 520-530° C., the duration is 5-6 hours, and the cooling method is water cooling.

4. The method for preparing a high conductivity cast aluminum alloy material according to claim 3, characterized in that: The aging treatment in step S3 is performed at a temperature of 190-200° C., for a duration of 5-6 hours, and in an air-cooling manner.

5. The method for preparing a high conductivity cast aluminum alloy material according to claim 2, characterized in that: The protective gas in step S1 is argon.

6. The method for preparing a high conductivity cast aluminum alloy material according to claim 2, characterized in that: The heat preservation and standing time in step S1 is 15 to 20 minutes.

7. The method for preparing a high conductivity cast aluminum alloy material according to any one of claims 2 to 6, characterized in that: In step S2, the mold is preheated to 275-285° C. before pouring and sprayed with a release agent.

8. Use of the high conductivity cast aluminum alloy material as claimed in claim 1 in preparing conductor components for high voltage switches.

Images