High-strength high-temperature-resistant forged aluminum alloy and preparation method thereof

Abstract

The invention discloses a high-strength and high-temperature-resistant forged aluminum alloy and a preparation method, and belongs to the technical field of non-ferrous metals, the high-strength aluminum alloy comprises the following components in percentage by mass: 4.5-6.5% of Cu, 0.5-0.8% of Mg, 0.5-0.8% of Ag, 0.5-1% of Mn, 0.3-0.8% of Zr, and the balance of Al and inevitable impurities; the preparation method of the high-strength aluminum alloy comprises the following steps: firstly, preparing an aluminum alloy ingot; then, the aluminum alloy cast ingot is subjected to homogenization treatment; secondly, the aluminum alloy cast ingot is forged, and the forging temperature ranges from 420 DEG C to 460 DEG C; and finally, the forged aluminum alloy cast ingot is subjected to two-stage solution treatment and aging treatment, and the high-strength aluminum alloy is obtained. The high-strength aluminum alloy has better high temperature resistance than the traditional alloy at 180-250 DEG C, so that the high-strength aluminum alloy can be widely applied to the manufacturing fields of aerospace, weaponry and high-end equipment.

Description

Technical Field

[0001] The invention relates to the technical field of nonferrous metals, and in particular to a high-strength and high-temperature resistant forged aluminum alloy and a preparation method thereof. Background Art

[0002] In recent years, with the development of modern aerospace industry, the high-temperature performance of aluminum alloy materials has ushered in more stringent challenges. At present, the performance of 7xxx series aluminum alloy forgings, led by 7050, 7075, etc., can no longer match the performance standards required by today's aerospace metal structural parts. Above 150°C, the performance of 7xxx series alloys decreases rapidly and significantly. 2XXX series aluminum alloys have excellent comprehensive properties such as low density, high specific strength, excellent corrosion resistance, good machinability, and abundant resources. They are widely used in industry, construction, transportation and other industries. However, 2XXX series aluminum alloys also have the problem of decreased mechanical properties above 200°C.

[0003] Based on the above problems, it is necessary to develop a high-temperature resistant aluminum alloy that can maintain excellent comprehensive performance after long-term heat exposure at 200°C. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a high-strength and high-temperature resistant forged aluminum alloy and a preparation method thereof, and improves the performance of the aluminum alloy by composite addition of Mn and Zr elements.

[0005] The present invention is achieved through the following technical solutions: A high-strength and high-temperature resistant forged aluminum alloy comprises, by mass percentage, 4.5-6.5% Cu, 0.5-0.8% Mg, 0.5-0.8% Ag, 0.5-1% Mn, 0.3-0.8% Zr, and the rest being Al and inevitable impurities.

[0006] Preferably, the high-strength aluminum alloy has a yield strength of 502-515 MPa, a tensile strength of 529-543 MPa, and an elongation of 7.6-10.1%.

[0007] A method for preparing a high-strength and high-temperature resistant forged aluminum alloy comprises the following steps: Step 1, preparing an aluminum alloy ingot; Step 2, homogenizing the aluminum alloy ingot; Step 3: forging the aluminum alloy ingot obtained in step 2 at a forging temperature of 420°C-460°C.

[0008] Step 4, performing a double-stage solid solution treatment and an aging treatment on the forged aluminum alloy ingot to obtain a high-strength aluminum alloy; The process of the two-stage solution treatment is as follows: heating the aluminum alloy ingot to 440-480°C at a heating rate of 1-3°C / min, keeping the temperature for 6-10h; then heating the ingot to 500-540°C at a heating rate of 1-3°C / min, keeping the temperature for 8-12h, and then immediately quenching; The aging treatment process is as follows: aging temperature 175-195° C., heat preservation time 5-8 hours, and cooling to room temperature.

[0009] Preferably, in step 1, a smelting method is used to prepare an aluminum alloy ingot, and the smelting temperature is 700-740°C.

[0010] Preferably, the homogenization process in step 2 is: The aluminum alloy ingot was heated to 460°C, kept warm for 5 hours, and then cooled to room temperature along with the furnace.

[0011] Preferably, the forging of the aluminum alloy ingot in step 3 includes pre-forging and final forging; The pre-forging process is: heating the aluminum alloy ingot to 400-420℃ and keeping it warm for 1 hour, and then performing multi-directional forging with a deformation of 30%-40%; The final forging process is: forging temperature is 420-460℃, deformation amount: 40%-70%; Preferably, the hammer speed of the pre-forging is 9 m / s; the pressing speed of the final forging is 2-0.5 mm / s with a uniform deceleration, and the pressing underpressure is 3 mm.

[0012] Preferably, the forging of the aluminum alloy ingot also includes the following process: Heat the forging hammer and lower anvil to 120℃ before pre-forging.

[0013] Preferably, the quenching method in the two-stage solution treatment in step 4 is water quenching.

[0014] Preferably, the cooling method of the aging treatment in step 4 is air cooling.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: The present application provides a high-strength and high-temperature resistant forged aluminum alloy, which uses the composite addition of Mn and Zr elements to improve the performance of the aluminum alloy. The composite addition of Mn and Zr can refine the grain size, reduce the volume fraction of the eutectic phase in the alloy, increase the recrystallization temperature of the aluminum alloy, promote the precipitation of the main strengthening phase, make the alloy have better strength and higher plasticity, and ultimately greatly improve the strength or plasticity of the aluminum alloy; secondly, combined with the heat treatment process, quenching obtains a supersaturated solid solution, and at an aging temperature of 175-195℃, the nano-scale Ω (Al2Cu) strengthening phase in the alloy precipitates and disperses in the matrix, pinning dislocations, grain boundaries and subgrain boundaries, hindering the migration of dislocations, grain boundaries and subgrain boundaries, and increasing the recrystallization temperature of the aluminum alloy, and ultimately greatly improving the strength of the aluminum alloy. The high-strength aluminum alloy has better high temperature resistance than traditional alloys at 180℃-250℃. Compared with 7050 aluminum alloy, this alloy has better mechanical properties at 200℃, so that the alloy can be widely used in aerospace, weapon equipment and high-end equipment manufacturing fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 This is a cast metallographic image corresponding to a high-strength and high-temperature resistant forged aluminum alloy according to Example 1 of the present invention.

[0018] Figure 2 This is a SEM image of a new type of high-strength aluminum alloy in solid solution state corresponding to Example 1 of the present invention.

[0019] Figure 3 The tensile stress-strain curves of a new type of high-strength aluminum alloy corresponding to Example 1, Example 2 and Comparative Example 1 of the present invention at room temperature are shown.

[0020] Figure 4 Schematic diagram of multi-directional forging: 1 punch and 1 pull.

[0021] Figure 5 This is a metallographic image of a high-strength aluminum alloy in a solid solution cast state corresponding to Comparative Example 1 of the present invention.

[0022] Figure 6 This is a SEM image of the solid solution state of the high-strength aluminum alloy corresponding to Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0025] A high-strength and high-temperature resistant forged aluminum alloy comprises, by mass percentage, 4.5-6.5% Cu, 0.5-0.8% Mg, 0.5-0.8% Ag, 0.5-1% Mn, 0.3-0.8% Zr, and the rest is Al and inevitable impurities.

[0026] The high-strength aluminum alloy has a yield strength of 502-515 MPa, a tensile strength of 529-543 MPa, and an elongation of 7.6-10.1%.

[0027] The high-strength aluminum alloy improves the performance of the aluminum alloy by adding Mn and Zr elements in combination. The addition of Mn and Zr elements can significantly refine the structure of the aluminum alloy, increase the recrystallization temperature of the aluminum alloy, promote the precipitation of the main strengthening phase, and ultimately greatly improve the strength or plasticity of the aluminum alloy. Through appropriate heat treatment processes, the dispersion strengthening effect of the Ω phase is significant. At the same time, Mn and Zr improve the thermal stability of the precipitation phase, which can improve the strength while ensuring plasticity. The high-strength aluminum alloy has better high temperature resistance at 180℃-250℃ than traditional alloys.

[0028] Based on the above high-strength aluminum alloy, the present application also provides a method for preparing a high-strength and high-temperature resistant forged aluminum alloy, comprising the following steps: Step 1, preparing an aluminum alloy ingot; Step 2, homogenizing the aluminum alloy ingot; Step 3: forging the aluminum alloy ingot obtained in step 2 at a forging temperature of 420°C-460°C.

[0029] The forging includes pre-forging and final forging; The pre-forging process is: heating the aluminum alloy ingot to 400-420℃ and keeping it warm for 1h, and then performing multi-directional forging, with a deformation of 30%-40% and a hammering speed of 9m / s; The final forging process is as follows: forging temperature is 420-460℃, pressing speed is 2-0.5mm / s uniform deceleration, pressing underpressure is 3mm, deformation is 40%-70%; Step 4, performing a double-stage solid solution treatment and an aging treatment on the forged aluminum alloy ingot to obtain a high-strength aluminum alloy; The process of the double-stage solution treatment is as follows: heating the aluminum alloy ingot to 440-480°C at a heating rate of 1-3°C / min, and keeping the temperature for 6-10h; then heating the ingot to 500-540°C at a heating rate of 1-3°C / min, and keeping the temperature for 8-12h, followed by immediate water quenching; The aging treatment process is as follows: aging temperature 175-195° C., insulation time 5-8 hours, and air cooling to room temperature.

[0030] The preparation method of the present application reduces the volume fraction of the eutectic phase by composite addition of Mn and Zr, so that the alloy has better strength and higher plasticity; then adopts an appropriate heat treatment process and quenches to obtain a supersaturated solid solution. At an aging temperature of 175-195°C, the nanoscale Ω (Al2Cu) strengthening phase in the alloy precipitates and is dispersed in the matrix, and pins dislocations, grain boundaries and subgrain boundaries to hinder the migration of dislocations, grain boundaries and subgrain boundaries, thereby increasing the recrystallization temperature of the aluminum alloy, and ultimately greatly improving the strength of the aluminum alloy. At the same time, the composite addition of Mn and Zr greatly improves the thermal stability of the nanoscale strengthening phase in the temperature range of 180°C-250°C; the preparation method improves the comprehensive performance and thermal stability of the alloy through an appropriate heat treatment system by optimizing the forging process, alloy solid solution treatment process and aging treatment process of the aluminum alloy.

[0031] Example 1 A method for preparing a high-strength and high-temperature resistant forged aluminum alloy comprises the following steps: S1. According to mass percentage, Cu: 5.2%, Mg: 0.67%, Ag: 0.65%, Mn: 0.8%, Zr: 0.5% and the rest Al are uniformly mixed and then smelted to obtain an aluminum alloy ingot.

[0032] Put the mixed raw materials into the melting furnace. When loading the furnace, it should be noted that the various materials should be evenly distributed, and overheating should be prevented during the melting process; after the melting liquid surface of the materials is horizontal, the melt should be properly stirred to make the temperature uniform, which is also conducive to accelerating the melting; when all the materials are melted to the melting temperature, the slag can be removed and refined to remove impurities and gases in the melt, so as to improve the purity and quality of the alloy; the refined melt is poured into a casting mold and cooled and solidified into an ingot.

[0033] Melting temperature: 700-740℃, the melting temperature of Al, Mn and Zr is 740℃, and the melting temperature of Cu, Mg and Ag is 720℃.

[0034] S2. Heat the ingot to 460°C, keep it warm for 5 hours, cool it to room temperature with the furnace, and perform homogenization treatment on the ingot.

[0035] S3, forging the aluminum alloy ingot obtained in step 2.

[0036] Before forging, the sharp edges and corners of the aluminum alloy ingot need to be polished off to avoid cracks caused by stress concentration; at the same time, lubricant needs to be applied to the surface of the billet to avoid uneven deformation of the sample and thus cracking of the sample; The temperature difference between the specimen and the forging hammer before forging will affect the formability of the workpiece, so the forging hammer and the lower anvil are heated to 120°C in advance.

[0037] Pre-forging: After the preparatory work before forging is completed, the aluminum alloy ingot is heated to 420℃ and then kept warm for 1h, and then multi-directional forging is performed in three mutually perpendicular directions, 3 upsetting and 3 drawing forging is performed, each deformation is 30%, and the hammering speed is 9m / s; the pre-forging is obtained; Final forging: Final forging temperature is 460℃, pressing speed: 2mm / s uniform deceleration, pressing underpressure: 3mm, deformation is 40%. S4, performing a double-stage solution treatment and an aging treatment on the aluminum alloy forging in sequence to obtain a high-strength aluminum alloy; The two-stage solution treatment process is as follows: the forging is heated to 460°C at a heating rate of 1°C / min and kept at this temperature for 8 hours; then heated to 520°C at a heating rate of 1°C / min and kept at this temperature for 10 hours, followed by immediate water quenching; The aging treatment process is: aging temperature 185°C, holding time 5h, and air cooling to room temperature.

[0038] like Figure 1 As shown, the average grain size of the alloy with 0.8% Mn and 0.43% Zr added in this embodiment is 93 μm, while the average grain size of the conventional high-strength Al-Cu-Mg-Ag alloy (Comparative Example 1) is about 350 μm. The addition of Mn and Zr significantly refines the grains.

[0039] Figure 2 The SEM image of the solid solution state of the cast alloy of this embodiment is shown, and the volume fraction of large particles is about 0.85%. The volume fraction of the excess AlCuFe phase is small, indicating that the alloy is compatible with the heat treatment process, and the eutectic phase is basically dissolved back into the matrix, ensuring the subsequent precipitation of the strengthening phase.

[0040] A high-strength and high-temperature resistant forged aluminum alloy corresponding to this embodiment is subjected to room temperature tensile test according to GB / T 228.1-2010 "Metallic Materials Tensile Test Part 1: Room Temperature Test Method". The tensile stress-strain curve at room temperature is as follows: Figure 3 As shown, the yield strength, tensile strength and elongation values ​​corresponding to the tensile stress-strain curve at room temperature are shown in Table 1.

[0041] The obtained high-strength aluminum alloy aged sample was subjected to heat exposure treatment at 200°C to determine its thermal stability.

[0042] The high-strength aluminum alloy was subjected to heat exposure treatment, heated to 200°C in a furnace, kept at this temperature for 20 hours, and then air-cooled to room temperature.

[0043] After heat exposure treatment, the yield strength of the high-strength aluminum alloy is 502Mpa, the tensile strength is 529Mpa, and the elongation is 10.1%. The room temperature yield strength of the high-strength aluminum alloy is 504Mpa, the tensile strength is 532Mpa, and the elongation is 8.4%. This shows that the strength and ductility of the alloy are maintained at good performance indicators before and after long-term heat exposure at 200℃: yield strength>500MPa; elongation>5%. After 20h of heat exposure at 200℃, the strength of this alloy only decreases slightly, and it has good thermal stability.

[0044] Example 2 A method for preparing a high-strength and high-temperature resistant forged aluminum alloy comprises the following steps: S1. According to mass percentage, Cu: 6.1%, Mg: 0.73%, Ag: 0.61%, Mn: 0.67%, Zr: 0.43% and the rest Al are mixed evenly and then smelted to obtain an aluminum alloy ingot.

[0045] S2. Heat the ingot to 460°C, keep it warm for 5 hours, cool it to room temperature with the furnace, and perform homogenization treatment on the ingot.

[0046] S3, forging the aluminum alloy ingot obtained in step 2.

[0047] Before pre-forging, heat the forging hammer and lower anvil to 140℃.

[0048] Pre-forging process: heat the aluminum alloy ingot to 410℃ and keep it warm for 1h, then perform 3 upsets and 3 draws forging, each time with a deformation of 30% and a hammering speed of 9m / s; after obtaining the pre-forged part, perform final forging; Final forging process: Final forging temperature is 460℃, pressing speed: 1mm / s uniform deceleration, pressing underpressure: 3mm, deformation is 50%. S4, performing a double-stage solid solution treatment and an aging treatment on the aluminum alloy forging to obtain a high-strength aluminum alloy; The two-stage solution treatment process is as follows: the forging is heated to 460°C at a heating rate of 1°C / min and kept at this temperature for 8 hours; then heated to 520°C at a heating rate of 1°C / min and kept at this temperature for 10 hours, followed by immediate water quenching. The aging treatment process is: aging temperature 185°C, holding time 5h, and air cooling to room temperature.

[0049] A high-strength and high-temperature resistant forged aluminum alloy corresponding to Example 2 is subjected to room temperature tensile test according to GB / T 228.1-2010 "Metallic Materials Tensile Test Part 1: Room Temperature Test Method". The tensile stress-strain curve at room temperature is as follows: Figure 3 As shown, the yield strength, tensile strength and elongation values ​​corresponding to the tensile stress-strain curve at room temperature are shown in Table 1.

[0050] Example 3 A method for preparing a high-strength and high-temperature resistant forged aluminum alloy comprises the following steps: S1. According to mass percentage, Cu: 4.5%, Mg: 0.8%, Ag: 0.5%, Mn: 1%, Zr: 0.8% and the rest Al are mixed evenly and then smelted to obtain an aluminum alloy ingot.

[0051] S2. Heat the ingot to 460°C, keep it warm for 5 hours, cool it to room temperature with the furnace, and perform homogenization treatment on the ingot.

[0052] S3, forging the aluminum alloy ingot obtained in step 2.

[0053] Before pre-forging, heat the forging hammer and lower anvil to 150℃.

[0054] Pre-forging process: heat the aluminum alloy ingot to 420℃ and keep it warm for 1h, then perform 3 upsets and 3 draws forging, each deformation is 40%, and the hammer speed is 9m / s; after obtaining the pre-forged part, perform final forging; Final forging process: Final forging temperature is 430℃, pressing speed: 1mm / s uniform deceleration, pressing underpressure: 3mm, deformation is 70%. S4, performing a double-stage solid solution treatment and an aging treatment on the aluminum alloy forging to obtain a high-strength aluminum alloy; The two-stage solution treatment process is as follows: the forging is heated to 440°C at a heating rate of 2°C / min and kept at this temperature for 6 hours; then heated to 540°C at a heating rate of 2°C / min and kept at this temperature for 12 hours, followed by immediate water quenching; The aging treatment process is: aging temperature 175°C, holding time 7h, and air cooling to room temperature.

[0055] Example 4 A method for preparing a high-strength and high-temperature resistant forged aluminum alloy comprises the following steps: S1. According to mass percentage, Cu: 6.5%, Mg: 0.5%, Ag: 0.8%, Mn: 0.5%, Zr: 0.3% and the rest Al are mixed evenly and then smelted to obtain an aluminum alloy ingot.

[0056] S2. Heat the ingot to 460°C, keep it warm for 5 hours, cool it to room temperature with the furnace, and perform homogenization treatment on the ingot.

[0057] S3, forging the aluminum alloy ingot obtained in step 2.

[0058] Before pre-forging, heat the forging hammer and lower anvil to 130℃.

[0059] Pre-forging process: heat the aluminum alloy ingot to 415℃ and keep it warm for 1h, then perform 3 upsets and 3 draws forging, each time with a deformation of 35% and a hammering speed of 9m / s; after obtaining the pre-forged part, perform final forging; Final forging process: Final forging temperature is 450℃, pressing speed: 1.5mm / s uniform deceleration, pressing underpressure: 3mm, deformation is 60%.

[0060] S4, performing a double-stage solid solution treatment and an aging treatment on the aluminum alloy forging to obtain a high-strength aluminum alloy; The two-stage solution treatment process is as follows: the forging is heated to 480°C at a heating rate of 3°C / min and kept at this temperature for 10 hours; then heated to 500°C at a heating rate of 3°C / min and kept at this temperature for 8 hours, followed by immediate water quenching; The aging treatment process is: aging temperature 195°C, holding time 8h, and air cooling to room temperature.

[0061] Comparative Example 1: A method for preparing a high-strength and high-temperature resistant forged aluminum alloy comprises the following steps: S1. According to mass percentage, 5.3% Cu, 0.49% Mg, 0.54% Ag, and the rest Al and inevitable impurities are uniformly mixed and then smelted to obtain an aluminum alloy ingot.

[0062] S2. The ingot obtained in S1 is homogenized at 460°C for 5 hours and then immediately quenched. S3. The ingot obtained in S2 is subjected to a two-stage solid solution treatment, firstly heated to 500°C at a heating rate of 1.5°C / min and kept at this temperature for 9 hours; then heated to 540°C at a heating rate of 1°C / min and kept at this temperature for 6 hours, and then immediately quenched.

[0063] S4. Perform aging treatment on the alloy obtained in S3, raise the temperature to 185°C in the furnace, keep it at that temperature for 4 hours, and then air-cool it to room temperature to obtain a traditional high-strength aluminum alloy material. The high-strength aluminum alloy of Comparative Example 1 does not have Mn and Zr elements added thereto, and the difference between the preparation process and that of the present application is that no forging process is performed, and the remaining processes are basically the same. Figure 5 Shown is the metallographic image of the as-cast aluminum alloy after solid solution in Comparative Example 1. Figure 1 The average grain size of the alloy with Mn and Zr added in Example 1 is 93 μm. Figure 5For Comparative Example 1, the average size of the conventional high-strength alloy is 343 μm, so the composite addition of Mn and Zr makes the grains significantly refined.

[0064] Figure 6 The SEM image of the aluminum alloy in Comparative Example 1 is shown. Statistics show that the volume fraction of large particles is about 1.9%. Figure 2 The SEM image of the cast alloy corresponding to the alloy added with Mn and Zr in Example 1 is shown, and the volume fraction of large particles is about 0.85%, and the volume fraction of the eutectic phase in Example 1 is significantly lower than that in Comparative Example 1. Therefore, the addition of Mn and Zr is beneficial to reduce the volume fraction of the eutectic phase, thereby improving the comprehensive properties of the alloy.

[0065] The high-strength aluminum alloy forgings corresponding to Comparative Example 1 were subjected to room temperature tensile tests according to GB / T 228.1-2010 "Tensile tests on metallic materials - Part 1: Room temperature test methods", and the performance changes are shown in Table 1.

[0066] Comparative Example 2 A method for preparing 7050 aluminum alloy comprises the following steps: S1. According to the mass percentage, Zn: 6.48%, Mg: 2.63%, Cu: 2.83%, Mn: 0.20%, Zr: 0.23%, Ti: 0.26%, and the rest is Al, and then mixed evenly and smelted to obtain an aluminum alloy ingot.

[0067] S2. Heat the ingot to 470°C, keep it warm for 48 hours, and cool it to room temperature in the furnace.

[0068] S3. Before forging, the sharp part of the blank needs to be polished smooth in advance to prevent the specimen from cracking due to stress concentration. Apply emulsion lubricant on the surface of the blank to avoid cracks caused by uneven deformation of the specimen. There will be a temperature difference between the specimen and the forging hammer before forging, which affects the formability, so the forging hammer and the lower anvil are heated to 120-150°C. After the pre-forging work is completed, the blank is continued to be heated, and the blank is heated to 370°C and then kept warm for 4 hours. First, 3 upsets and 3 pulls are performed forging, each with a deformation of 30% and a hammering speed of 9m / s. After obtaining the pre-forging, final forging is performed, the final forging temperature is 310°C, the pressing speed: 2-0.5mm / s uniform deceleration, the pressing underpressure: 3mm, and the deformation: 40%-70%.

[0069] S4. The forgings obtained in S3 were subjected to a two-stage solid solution treatment, firstly heated to 470°C at a heating rate of 1.5°C / min and kept at that temperature for 3h; then heated to 485°C at a heating rate of 1°C / min and kept at that temperature for 6h, and then immediately quenched.

[0070] S6: The alloy obtained in S5 is subjected to aging treatment, the temperature is raised to 165°C in the furnace, kept at this temperature for 18 hours, and then air-cooled to room temperature to obtain a high-strength aluminum alloy material.

[0071] Comparative Example 2 is a control 7050 high-strength aluminum alloy aged sample. The high-strength aluminum alloy forging corresponding to Comparative Example 2 is subjected to room temperature tensile test according to GB / T 228.1-2010 "Metallic Materials Tensile Test Part 1: Room Temperature Test Method" standard. The yield strength, tensile strength and elongation values ​​corresponding to the tensile stress-strain curve at room temperature are shown in Table 1. Comparative Example 3 A method for preparing 7050 aluminum alloy comprises the following steps: S1. According to the mass percentage, Zn: 6.48%, Mg: 2.63%, Cu: 2.83%, Mn: 0.20%, Zr: 0.23%, Ti: 0.26%, and the rest is Al and inevitable impurities, and then mixed evenly and smelted to obtain an aluminum alloy ingot.

[0072] S2. Heat the ingot to 470°C, keep it warm for 48 hours, and cool it to room temperature in the furnace.

[0073] S4: Before forging, the sharp part of the blank needs to be polished smooth in advance to prevent the specimen from cracking due to stress concentration. Apply emulsion lubricant on the surface of the blank to avoid cracks caused by uneven deformation of the specimen. There will be a temperature difference between the specimen and the forging hammer before forging, which affects the formability, so the forging hammer and the lower anvil are heated to 120-150°C. After the pre-forging work is completed, the blank is continued to be heated, and the blank is heated to 370°C and then kept warm for 4h. First, 3 upsets and 3 pulls are performed, with a deformation of 30% each time and a hammering speed of 9m / s. After obtaining the pre-forging, the final forging is carried out, the final forging temperature is 310°C, the pressing speed: 2-0.5mm / s uniform deceleration, the pressing underpressure: 3mm, and the deformation: 40%-70%. S5: The forgings obtained in S4 were subjected to a two-stage solid solution treatment, firstly heated to 470°C at a heating rate of 1.5°C / min and kept at that temperature for 3h; then heated to 485°C at a heating rate of 1°C / min and kept at that temperature for 6h, and then immediately quenched.

[0074] S6: The alloy obtained in S5 is subjected to aging treatment, the temperature is raised to 165°C in the furnace, kept at this temperature for 18 hours, and then air-cooled to room temperature to obtain a high-strength aluminum alloy material.

[0075] S7: The alloy obtained in S6 is subjected to heat exposure treatment, the temperature is raised to 200°C in a furnace, kept at this temperature for 20 h, and then air-cooled to room temperature.

[0076] Comparative Example 3 is a control 7050 high-strength aluminum alloy aged sample. The high-strength aluminum alloy forging corresponding to Comparative Example 3 is subjected to room temperature tensile test according to GB / T 228.1-2010 "Metallic Materials Tensile Test Part 1: Room Temperature Test Method". The yield strength, tensile strength and elongation values ​​corresponding to the tensile stress-strain curve at room temperature are shown in Table 1. After heat exposure at 200°C, the strength of the 7050 aluminum alloy decreases sharply, with a decrease of 35.6%.

[0077] The mechanical properties of Example 1, Example 2 and Comparative Example 2, Comparative Example 3 are shown in Table 1.

[0078] Tensile properties test: Based on GB / T 228.1-2010 "Tensile test of metallic materials Part 1: Room temperature test method".

[0079] Table 1. Mechanical properties of alloys

[0080] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A high-strength and high-temperature resistant forged aluminum alloy, characterized in that: Calculated by mass percentage, it includes Cu: 4.5-6.5%, Mg: 0.5-0.8%, Ag: 0.5-0.8%, Mn: 0.5-1%, Zr: 0.3-0.8%, and the rest is Al and inevitable impurities.

2. The high-strength and high-temperature resistant forged aluminum alloy according to claim 1, characterized in that: The high-strength aluminum alloy has a yield strength of 502-515 MPa, a tensile strength of 529-543 MPa, and an elongation of 7.6-10.1%.

3. A method for preparing a high-strength and high-temperature resistant forged aluminum alloy according to claim 1 or 2, characterized in that: The following steps are involved: Step 1, preparing an aluminum alloy ingot; Step 2, homogenizing the aluminum alloy ingot; Step 3, forging the aluminum alloy ingot obtained in step 2 at a forging temperature of 420° C.-460° C.; Step 4, performing a double-stage solid solution treatment and an aging treatment on the forged aluminum alloy ingot to obtain a high-strength aluminum alloy; The process of the two-stage solution treatment is as follows: heating the aluminum alloy ingot to 440-480°C at a heating rate of 1-3°C / min, keeping the temperature for 6-10h; then heating the ingot to 500-540°C at a heating rate of 1-3°C / min, keeping the temperature for 8-12h, and then immediately quenching; The aging treatment process is as follows: aging temperature 175-195° C., heat preservation time 5-8 hours, and cooling to room temperature.

4. The method for preparing a high-strength and high-temperature resistant forged aluminum alloy according to claim 3, characterized in that: In step 1, a smelting method is adopted to prepare an aluminum alloy ingot, and the smelting temperature is 700-740°C.

5. The method for preparing a high-strength and high-temperature resistant forged aluminum alloy according to claim 3, characterized in that: The homogenization process in step 2 is: The aluminum alloy ingot was heated to 460°C, kept warm for 5 hours, and then cooled to room temperature along with the furnace.

6. The method for preparing a high-strength and high-temperature resistant forged aluminum alloy according to claim 3, characterized in that: The forging of the aluminum alloy ingot in step 3 includes pre-forging and final forging; The pre-forging process is: heating the aluminum alloy ingot to 400-420℃ and keeping it warm for 1 hour, and then performing multi-directional forging with a deformation of 30%-40%; The final forging process is: forging temperature is 420-460°C, deformation amount is 40%-70%.

7. The method for preparing a high-strength and high-temperature resistant forged aluminum alloy according to claim 3, characterized in that: The hammer speed of the pre-forging is 9m / s; the pressing speed of the final forging is 2-0.5mm / s with a uniform deceleration, and the pressing underpressure is 3mm.

8. The method for preparing a high-strength and high-temperature resistant forged aluminum alloy according to claim 3, characterized in that: The forging of the aluminum alloy ingot also includes the following process: Heat the forging hammer and lower anvil to 120℃ before pre-forging.

9. The method for preparing a high-strength and high-temperature resistant forged aluminum alloy according to claim 3, characterized in that: The quenching method in the two-stage solution treatment in step 4 is water quenching.

10. The method for preparing a high-strength and high-temperature resistant forged aluminum alloy according to claim 3, characterized in that: The cooling method of the aging treatment in step 4 is air cooling.

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