Aluminum alloy product and efficient preparation method thereof

Abstract

The invention belongs to the technical field of aluminum alloys, and particularly relates to an aluminum alloy product and an efficient preparation method thereof. The preparation method comprises the following steps: S1, casting an aluminum bar; step S2, carrying out homogenization treatment; s3, peeling the casting rod; step S4, preheating; step S5, extrusion: adopting a reverse extruder; step S6, traction; step S7, carrying out online quenching treatment; step S8, straightening or straightening; and S9, aging treatment is conducted. According to the method, online quenching treatment is adopted to replace traditional offline quenching treatment, the product outlet temperature is monitored in real time through infrared rays, the method has the beneficial effects of being short in period, low in cost, high in yield and high in generalizability, and the prepared 7075 aluminum alloy can meet the requirements that the tensile strength is larger than or equal to 560 MPa, the yield strength is larger than or equal to 500 MPa, the ductility is larger than or equal to 7%, the Brinell hardness HB is larger than or equal to 150, and the yield is not lower than 85%.

Description

Technical Field

[0001] The present invention belongs to the technical field of aluminum alloys, and in particular relates to an aluminum alloy product and an efficient preparation method thereof. Background Art

[0002] 7075 aluminum alloy, an Al-Zn-Mg-Cu alloy, boasts exceptional strength and hardness, and its excellent mechanical properties make it widely used in aerospace and rail transportation. In recent years, with the rapid development of new energy vehicles and construction machinery, driven by the continuous demand for lightweight materials and high mechanical performance, the application of 7075 aluminum alloy has been further expanded.

[0003] In the aluminum extrusion industry, 7075 aluminum alloy has poor extrudability and high quenching sensitivity, leading most companies to typically use offline quenching to produce T6 7075 aluminum alloy. A few companies have indirectly achieved online quenching of 7075 aluminum alloy by installing secondary heating equipment at the extruder outlet. For example, Chinese invention patent publication number CN1807004A discloses an online quenching method for 7075 aluminum alloy profiles. During the extrusion process, the product is heated to the quenching temperature in a hollow heating furnace and then water-cooled to achieve online quenching. However, due to the secondary heating equipment's inherent tendency to increase the tailing ratio of the forward extruder product, poor coordination with the reverse extruder, and high energy consumption, this method is rarely adopted by other companies. Some other companies have achieved online quenching treatment of 7075 aluminum alloy by optimizing the mold structure. For example, the Chinese invention patent with publication number CN108465713A discloses the processing technology and aluminum alloy profiles of 7075 aluminum alloy. Due to its unique mold structure, it is not suitable for reverse extrusion machines. At the same time, the extrusion speed of 0.8~1m / min is actually difficult to ensure that the product has sufficient online quenching temperature. In addition, quenching before pulling will cause waste of pulling material. Combined with the characteristics of long tail length in forward extrusion, the actual product yield is difficult to guarantee.

[0004] In summary, the present invention utilizes the high extrusion efficiency of the reverse extruder, optimizes the production links and rationally sets and monitors the process parameters of the relevant steps, thereby realizing an efficient method for preparing 7075 aluminum alloy. This method has the characteristics of short production cycle, low cost, high yield and strong scalability. Summary of the Invention

[0005] The present invention aims to overcome the shortcomings of the prior art and provide an aluminum alloy product and an efficient preparation method thereof. The 7075 aluminum alloy produced by the preparation method of the present invention has high mechanical properties, including a tensile strength of 560 MPa or greater, a yield strength of 500 MPa or greater, an elongation of 7%, and a Brinell hardness of HB 150 or greater. Compared with other methods, this method has the advantages of a short production cycle, low cost, high yield rate, and strong scalability.

[0006] To achieve the above technical objectives, the technical solution adopted in the embodiment of the present invention is: In a first aspect, an embodiment of the present invention provides an efficient method for preparing an aluminum alloy bar, comprising the following steps: Step S1, aluminum rod casting: aluminum ingots are melted and cast to obtain aluminum alloy cast rods; Step S2, homogenization treatment: performing homogenization treatment on the aluminum alloy cast rod obtained in step S1 to obtain a homogenized aluminum alloy cast rod; Step S3, peeling the cast rod: peeling the homogenized aluminum alloy cast rod obtained in step S2 to obtain a peeled aluminum alloy cast rod; Step S4, preheating: preheating the peeled aluminum alloy cast rod, extrusion die and die barrel obtained in step S3 respectively to obtain preheated peeled aluminum alloy cast rod, extrusion die and die barrel; Step S5, extrusion: using a reverse extruder, the peeled aluminum alloy cast rod preheated in step S4 is extruded through a die in a die barrel to continuously extrude an unquenched aluminum alloy product; Step S6, traction: a traction machine clamps the unquenched aluminum alloy product in step S5 at the discharge port of the reverse extruder and continues to traction until the extrusion process is completed; Step S7, online quenching treatment: During the pulling process described in step S6, the unquenched aluminum alloy product is passed through a water tank for cooling to obtain a quenched aluminum alloy product; Step S8, straightening or leveling: straightening or leveling the aluminum alloy product after quenching in step S7 to obtain an unaged aluminum alloy product that meets the straightness requirement; Step S9, aging treatment: The unaged aluminum alloy product meeting the straightness requirements in step S8 is artificially aged: the heating temperature is 145-155° C., the holding time is 4-6 hours, and the product is air-cooled after being taken out of the furnace to obtain the final aluminum alloy product.

[0007] Furthermore, in step S1, the aluminum alloy cast rod includes the following components, calculated by mass percentage: Si≤0.4%, Fe≤0.5%, Cu 1.2%-2.0%, Mn≤0.3%, Mg 2.1%-2.9%, Cr 0.18%-0.28%, Zn5.1%-6.1%, Ti≤0.2%, Zr+Ti≤0.25%, the total amount of other impurity elements ≤0.15%, and the balance is Al.

[0008] Furthermore, in step S2, the heating temperature of the homogenization treatment is 380-410°C, the holding time is 4-6 hours, and then the temperature is raised to 440-470°C, the holding time is 4-6 hours, and the product is air-cooled after being taken out of the furnace.

[0009] Furthermore, in step S3, the cast rod peeling is cold peeling of the cast rod, and the peeling thickness is 1 to 2.5 mm.

[0010] Furthermore, in step S4, the heating temperature of the peeled aluminum alloy cast rod is 430-470° C., the heating temperature of the extrusion die is 340-380° C., and the heating temperature of the die barrel is 340-380° C.; The extrusion die is a reverse extrusion die with a working zone width of 5 to 7 mm. A guide groove is provided on the side of the working zone close to the aluminum alloy casting rod. The inclination angle of the guide groove side wall is 3° to 8° and the width is 3 to 5 mm.

[0011] Furthermore, during the extrusion process of step S5, the discharge speed of the unquenched aluminum alloy product is 1 to 3 m / min.

[0012] Furthermore, during the pulling process in step S6, an infrared thermometer is used to monitor the product temperature at the extruder outlet, the horizontal distance between the infrared thermometer and the cooling water tank is no more than 400 mm, and the temperature of the aluminum alloy product is 460-500°C.

[0013] Furthermore, the online quenching method in step S7 is pile water cooling, the cooling water temperature during the process is not higher than 45°C, and the temperature of the product after cooling is not higher than 100°C.

[0014] Furthermore, in step S7, the traction machine clamps the product on the side of the water tank close to the extruder and moves in the water tank, continuing the traction action until the extrusion process is completed. After the product is clamped by the traction machine, pile water cooling is started until the product is completely pulled out of the water tank.

[0015] In a second aspect, an embodiment of the present invention provides an aluminum alloy bar, which is prepared by the preparation method described in the first aspect, and the finished aluminum alloy bar has a tensile strength ≥560MPa, a yield strength ≥500MPa, an elongation ≥7%, and a Brinell hardness HB ≥150.

[0016] The technical solution provided by the embodiment of the present invention has the following beneficial effects: The present invention replaces the traditional offline quenching treatment with an online quenching treatment, utilizes the high extrusion efficiency of a reverse extruder, combines the reverse extruder with pile water cooling, and adopts a specific mold structure and infrared temperature measurement and monitoring means, so as to efficiently prepare 7075 aluminum alloy products. The preparation method of the present invention has the characteristics of short production cycle, low cost, high yield and strong scalability.

[0017] The 7075 aluminum alloy product prepared by the present invention can meet the requirements of tensile strength ≥560MPa, yield strength ≥500MPa, elongation ≥7%, and Brinell hardness HB ≥150. By replacing the traditional offline quenching treatment with online quenching treatment, the quenching time can be effectively shortened and the manufacturing cost can be reduced. Referring to the vertical quenching furnace, it takes about 4 hours to quench 1 ton, consumes about 400 degrees of electricity, and the aging furnace is fully loaded with a capacity of about 20 tons. The present invention can shorten the manufacturing cycle by about 4 days and save about 240 yuan in electricity cost per tonnage. Taking advantage of the high extrusion efficiency of the reverse extruder, the reverse extruder is combined with pile water cooling, and a specific mold structure and infrared temperature measurement and monitoring means are adopted. The equipment of the present invention is convenient and feasible, and has the conditions for large-scale production and promotion and application. The yield rate of the produced 7075 aluminum alloy is not less than 85%. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the extrusion molding and online cooling process during the preparation of the aluminum alloy product in Example 1 of the present invention.

[0019] Figure 2 This is a top view of the extrusion die during the preparation of the aluminum alloy product in Example 1 of the present invention.

[0020] Figure 3 for Figure 2 Schematic cross-sectional view along line AA in the extrusion die.

[0021] Figure 4 This is the metallographic structure of the 7075 aluminum alloy prepared in Example 1 of the present invention.

[0022] Explanation of the accompanying symbols: 1—extrusion die; 11—guide groove; 12—working belt; 2—extrusion shaft; 3—die cylinder; 4—7075 aluminum alloy product during processing; 5—die shaft and bracket; 6—infrared thermometer; 7—water tank; 8—cooling water; 9—traction machine, D—horizontal distance between infrared thermometer and cooling water tank. DETAILED DESCRIPTION

[0023] In the description of the present invention, it should be understood that the directions or positional relationships indicated by directional words such as "inside, outside", "up, down", "left, right", etc. are usually based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention.

[0024] The present invention provides an efficient method for preparing aluminum alloy bars, comprising the following steps: Step S1, aluminum rod casting: aluminum ingots are melted and cast to obtain aluminum alloy cast rods; Step S2, homogenization treatment: homogenizing the aluminum alloy cast rod to obtain a homogenized aluminum alloy cast rod; Step S3, peeling the cast rod: peeling the homogenized aluminum alloy cast rod to obtain a peeled aluminum alloy cast rod; Step S4, preheating: preheating the peeled aluminum alloy cast rod, the extrusion die, and the die barrel respectively to obtain the preheated peeled aluminum alloy cast rod, the extrusion die, and the die barrel; Step S5, extrusion: using a reverse extruder, the preheated peeled aluminum alloy cast rod is extruded through a die in a die barrel to continuously extrude an unquenched aluminum alloy product; Step S6, traction: the traction machine clamps the unquenched aluminum alloy product at the discharge port of the reverse extruder and continues to traction until the extrusion process is completed; Step S7, online quenching treatment: During the pulling process, the unquenched aluminum alloy product is passed through a water tank for cooling to obtain a quenched aluminum alloy product; Step S8, straightening or leveling: straightening or leveling the quenched aluminum alloy product to obtain an unaged aluminum alloy product that meets the straightness requirement; Step S9, aging treatment: artificially aging the unaged aluminum alloy product that meets the straightness requirement to obtain the final aluminum alloy product.

[0025] like Figure 1 As shown, during the extrusion process of the present invention, the extrusion shaft 2 and die barrel 3 remain stationary relative to the aluminum alloy cast rod, but as a whole, they move rightward relative to the extrusion die 1. Leveraging the opposing forces of the die shaft and support 5, a 7075 aluminum alloy product 4 is extruded through the guide groove 11 and the working belt 12. Under the monitoring of an infrared thermometer 6, the 7075 aluminum alloy product 4 enters the water tank 7 at a constant speed and is clamped by the traction machine 9. Simultaneously, the water tank initiates an online quenching process, pumping cooling water 8 to a predetermined height until the extrusion and traction process is complete, achieving online quenching of the product.

[0026] In step S1, the aluminum alloy cast rod includes the following components, calculated by mass fraction: Si≤0.4%, Fe≤0.5%, Cu1.2-2.0%, Mn≤0.3%, Mg 2.1-2.9%, Cr 0.18-0.28%, Zn 5.1-6.1%, Ti≤0.2%, Zr+Ti≤0.25%, the total amount of other impurity elements ≤0.15%, and the balance is Al.

[0027] The homogenization treatment in step S2 is heated to 380-410°C for 4-6 hours, then raised to 440-470°C for 4-6 hours before air-cooling. Homogenization can improve compositional segregation and reduce casting stress, which helps improve metal fluidity during extrusion.

[0028] In step S3, the cast bar is cold-scaled to a thickness of 1 to 2.5 mm. This completely removes any surface defects, ensuring uniformity of the cast bar structure and preventing them from being carried over into the final extruded product during reverse extrusion, potentially rendering the final extruded product scrapped.

[0029] In step S4, the peeled aluminum alloy cast rods are heated to 430-470°C, the extrusion die is heated to 340-380°C, and the die barrel is heated to 340-380°C. Appropriate cast rod heating temperatures ensure that the product at the extruder outlet has a sufficient quenching temperature while preventing overheating of the product structure. Appropriate extrusion die and die barrel heating temperatures ensure consistent surface temperature and quality during the extrusion process.

[0030] like Figure 2 and Figure 3 As shown, in step S4, the extrusion die is a reverse extrusion die, and the width of the working band 12 is 5 to 7 mm. There is a guide groove 11 on the side of the working band 12 close to the aluminum alloy cast rod. The angle of the guide groove 11 is 3° to 8° and the width is 3 to 5 mm. Unlike forward extrusion, the product needs to be demolded after each extrusion stage in the reverse extrusion process. To ensure smooth demolding and facilitate the flow of metal during the extrusion process, the die is provided with a guide groove 11 with an angle of 3° to 8° and a width of 3 to 5 mm. The metal flows through the working band 12 through the guide groove 11. The working band with a width of 5 to 7 mm ensures that the working band has sufficient strength to prevent it from breaking during the extrusion process. At the same time, it avoids excessive friction between the working band and the product surface due to excessive width, thereby affecting the surface quality of the product.

[0031] The discharge speed of the unquenched aluminum alloy product during the extrusion process in step S5 is 1-3 m / min, which can ensure that the product at the discharge port of the extruder has a sufficient quenching temperature and avoid cracking of the product surface due to excessive speed.

[0032] Furthermore, during the traction process in step S6, an infrared thermometer is used to monitor the product temperature at the extruder outlet, and the horizontal distance between the infrared thermometer and the cooling water tank (e.g. Figure 1 The D) shown is not greater than 400mm, and the temperature of the aluminum alloy product is 460~500℃.

[0033] Furthermore, in step S7, the online quenching method is pile water cooling, and the cooling water temperature during the quenching process does not exceed 45°C. Pile water cooling eliminates the need for additional water baffles before and after the water tank during the online quenching process, allowing the tractor to smoothly perform the traction and clamping action near the water tank outlet and return to its original position after the extrusion and traction action is completed.

[0034] The haul-off machine clamps the product on the side of the water tank close to the extruder and moves it in the water tank, continuing the haul-off action until the extrusion process is completed. After the product is clamped by the haul-off machine, the pile water cooling is started until the product is completely pulled out of the water tank.

[0035] Cooling water can continuously enter and discharge the water tank through the huge water reservoir under the water tank. The quenching cooling water temperature is no higher than 45℃ and the temperature of the cooled product is no higher than 100℃, ensuring the quenching quality.

[0036] In step S9, the artificial aging heating temperature is 145-155°C, the holding time is 4-6 hours, and the alloy is air-cooled after leaving the furnace. Compared with the conventional two-stage aging process for 7075 aluminum alloy, which heats at 100-110°C for 7-9 hours, then raises the temperature to 145-155°C and holds for 7-9 hours, the holding time of the present invention is shortened by about three-quarters, without significantly reducing the performance of the final product.

[0037] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0038] Example 1 An efficient preparation method for an aluminum alloy product comprises the following steps: (1) Aluminum rod casting: Aluminum ingots are cast to obtain aluminum alloy cast rods. The aluminum alloy cast rods include the following components by mass fraction: Si 0.12%, Fe 0.29%, Cu 1.55%, Mn 0.14%, Mg 2.54%, Cr 0.21%, Zn 5.61%, Ti 0.04%, Zr 0.03%, Al 89.4%, and the balance is other impurity elements; (2) Homogenization treatment: The cast rod obtained in step (1) was kept at 400°C for 5 hours, then heated to 460°C, kept at this temperature for 5 hours, and then taken out of the furnace and air-cooled; (3) Cast rod peeling: Peel the homogenized cast rod obtained in step (2) by 1.5 mm; (4) Preheating: heating the homogenized cast rod obtained in step (3) to 470°C, heating the extrusion die to 350°C, and heating the die barrel to 350°C; The extrusion die is a reverse extrusion die with a guide groove of 5° and 5mm width and a working belt of 7mm width; (5) Extrusion: The cast bars preheated in step (4) are extruded using a 2500MN reverse extruder. The aluminum alloy discharge speed during the extrusion process is 1.5 m / min. (6) Traction: The product obtained in step (5) is tractioned, and an infrared thermometer is placed above the discharge port 400 mm away from the water tank. During the traction process, the discharge port temperature measured by the infrared thermometer is between 472 and 495 °C; (7) Online quenching treatment: The product obtained in step (6) is cooled by online water in a water tank, the cooling water temperature is 20°C, and the temperature of the cooled product is 25°C; (8) Straightening: The product obtained in step (7) is cut off at the head and tail and then straightened; (9) Aging treatment: The product obtained in step (8) is placed in an aging furnace for artificial aging treatment at a holding temperature of 150°C for 6 hours. After being taken out of the furnace, it is air-cooled to obtain a 7075 aluminum alloy bar product.

[0039] Example 2 An efficient preparation method for an aluminum alloy product comprises the following steps: (1) Aluminum rod casting: Aluminum ingots are cast to obtain aluminum alloy cast rods. The aluminum alloy cast rods include the following components by mass fraction: Si 0.12%, Fe 0.29%, Cu 1.55%, Mn 0.14%, Mg 2.54%, Cr 0.21%, Zn 5.61%, Ti 0.04%, Zr 0.03%, Al 89.4%, and the balance is other impurity elements; (2) Homogenization treatment: The cast rod obtained in step (1) was kept at 400°C for 5 hours, then heated to 460°C, kept at this temperature for 5 hours, and then taken out of the furnace and air-cooled; (3) Cast rod peeling: Peel the homogenized cast rod obtained in step (2) by 1.5 mm; (4) Preheating: heating the homogenized cast rod obtained in step (3) to 430°C, heating the extrusion die to 350°C, and heating the die barrel to 350°C; The extrusion die is a reverse extrusion die with a guide groove of 5° and 5mm width and a working belt of 7mm width; (5) Extrusion: The cast bars preheated in step (4) are extruded using a 2500MN reverse extruder. The aluminum alloy discharge speed during the extrusion process is 2 m / min. (6) Traction: The product obtained in step (5) is tractioned, and an infrared thermometer is placed above the discharge port 400 mm away from the water tank. During the traction process, the discharge port temperature measured by the infrared thermometer is between 465 and 486 °C; (7) Online quenching treatment: The product obtained in step (6) is cooled by online water in a water tank, the cooling water temperature is 20°C, and the temperature of the cooled product is 25°C; (8) Straightening: The product obtained in step (7) is cut off at the head and tail and then straightened; (9) Aging treatment: The product obtained in step (8) is placed in an aging furnace for artificial aging treatment at a holding temperature of 150°C for 4 hours. After being taken out of the furnace, it is air-cooled to obtain a 7075 aluminum alloy bar product.

[0040] Example 3 An efficient preparation method for an aluminum alloy product comprises the following steps: (1) Aluminum rod casting: Aluminum ingots are cast to obtain aluminum alloy cast rods. The aluminum alloy cast rods include the following components by mass fraction: Si 0.11%, Fe 0.18%, Cu 1.31%, Mn 0.02%, Mg 2.22%, Cr 0.19%, Zn 5.39%, Ti 0.03%, Zr 0.01%, Al 90.5%, and the balance is other impurity elements; (2) Homogenization treatment: The cast rod obtained in step (1) was kept at 390°C for 5 hours, then heated to 450°C, kept at this temperature for 5 hours, and then taken out of the furnace and air-cooled; (3) Cast rod peeling: The homogenized cast rod obtained in step (2) is cold peeled to a peeling thickness of 1.5 mm; (4) Preheating: heating the homogenized cast rod obtained in step (3) to 450°C, heating the extrusion die to 350°C, and heating the die barrel to 350°C; The extrusion die is a reverse extrusion die with a guide groove of 5° and 5mm width and a working belt of 7mm width; (5) Extrusion: The cast bars preheated in step (4) are extruded using a 2500MN reverse extruder. The aluminum alloy discharge speed during the extrusion process is 1.5 m / min. (6) Traction: The product obtained in step (5) is tractioned, and an infrared thermometer is placed above the discharge port 400 mm away from the water tank. During the traction process, the discharge port temperature measured by the infrared thermometer is between 466 and 488 °C; (7) Online quenching treatment: The product obtained in step (6) is cooled by online water in a water tank, the cooling water temperature is 20°C, and the temperature of the cooled product is 25°C; (8) Straightening: The product obtained in step (7) is cut off at the head and tail and then straightened; (9) Aging treatment: The product obtained in step (8) is placed in an aging furnace for artificial aging treatment at a holding temperature of 150°C for 6 hours. After being taken out of the furnace, it is air-cooled to obtain a 7075 aluminum alloy bar product.

[0041] Comparative Example 1 A method for preparing an aluminum alloy product comprises the following steps: (1) Aluminum rod casting: Aluminum ingots are cast to obtain aluminum alloy cast rods. The aluminum alloy cast rods include the following components by mass percentage: Si 0.12%, Fe 0.29%, Cu 1.55%, Mn 0.14%, Mg 2.54%, Cr 0.21%, Zn 5.61%, Ti 0.04%, Zr 0.03%, Al 89.4%, and the balance is other impurity elements; (2) Homogenization treatment: The cast rod obtained in step (1) was kept at 400°C for 5 hours, then heated to 460°C, kept at this temperature for 5 hours, and then taken out of the furnace and air-cooled; (3) Cast rod peeling: Peel the homogenized cast rod obtained in step (2) by 1.5 mm; (4) Preheating: heating the homogenized cast rod obtained in step (3) to 430°C, heating the extrusion die to 350°C, and heating the die barrel to 350°C; The extrusion die is a reverse extrusion die with a guide groove of 5° and 5mm width and a working belt of 7mm width; (5) Extrusion: The cast bars preheated in step (4) are extruded using a 2500MN reverse extruder. The aluminum alloy discharge speed during the extrusion process is 2 m / min. (6) Traction: Traction of the product obtained in step (5); (7) Offline quenching treatment: The product obtained in step (6) is quenched in a vertical quenching furnace at a quenching holding temperature of 470°C for 1 hour. After being taken out of the furnace, it is water-cooled at a cooling water temperature of 50°C. (8) Straightening: The product obtained in step (7) is cut off at the head and tail and then straightened; (9) Aging treatment: The product obtained in step (8) is placed in an aging furnace for artificial aging treatment at a holding temperature of 150°C for 6 hours. After being taken out of the furnace, it is air-cooled to obtain a 7075 aluminum alloy bar product.

[0042] Comparative Example 2 A method for preparing an aluminum alloy product comprises the following steps: (1) Aluminum rod casting: The chemical composition of the aluminum alloy is expressed in percentage by mass: Si 0.12%, Fe 0.29%, Cu 1.55%, Mn 0.14%, Mg 2.54%, Cr 0.21%, Zn 5.61%, Ti 0.04%, Zr 0.03%, Al 89.4%, and the balance is other impurity elements; (2) Homogenization treatment: The cast rod obtained in step (1) was kept at 400°C for 5 hours, then heated to 460°C, kept at this temperature for 5 hours, and then taken out of the furnace and air-cooled; (3) Cast rod peeling: Peel the homogenized cast rod obtained in step (2) by 1.5 mm; (4) Preheating: heating the homogenized cast rod obtained in step (3) to 430°C, heating the extrusion die to 350°C, and heating the die barrel to 350°C; The extrusion die is a reverse extrusion die with a guide groove of 5° and 5mm width and a working belt of 7mm width; (5) Extrusion: The cast bars preheated in step (4) are extruded using a 2500MN reverse extruder. The aluminum alloy discharge speed during the extrusion process is 2 m / min. (6) Traction: The product obtained in step (5) is tractioned, and an infrared thermometer is placed above the discharge port 400 mm away from the water tank. During the traction process, the discharge port temperature measured by the infrared thermometer is between 465 and 488 °C; (7) Online quenching treatment: The product obtained in step (6) is cooled by online water in a water tank, the cooling water temperature is 20°C, and the temperature of the cooled product is 25°C; (8) Straightening: The product obtained in step (7) is cut off at the head and tail and then straightened; (9) Aging treatment: The product obtained in step (8) is placed in an aging furnace for artificial aging treatment. The aging holding temperature is 105°C for 8 hours, and then the temperature is raised to 150°C and kept at this temperature for 8 hours. After being taken out of the furnace, the product is air-cooled to obtain a 7075 aluminum alloy bar product.

[0043] To verify the impact of the aluminum alloy preparation method of the present invention on the performance of 7075 aluminum alloy products, the 7075 aluminum alloy products obtained in Examples 1-3 and Comparative Examples 1-2 were tested for tensile strength, yield strength, elongation, and hardness using methods familiar to those skilled in the art. Testing equipment included an INSTRON 5982 mechanical testing machine and a Laizhou Huayin HB-3000B Brinell hardness tester. A test sample was taken from the head and tail of each example and comparative example product. The test results and product appearance are shown in Table 1.

[0044] Table 1 Performance and hardness test results and appearance of products in Examples 1-3 of the present invention and Comparative Examples 1-2 GB / T 3191-2019, Aluminum and Aluminum Alloy Extruded Bars, specifies mechanical property requirements for 7075-T6 extruded bars: tensile strength ≥ 560 MPa, yield strength ≥ 500 MPa, elongation ≥ 7%, and a Brinell hardness (HB) reference value of 150. GB / T 6892-2015, Aluminum and Aluminum Alloy Extruded Profiles for General Industrial Use, specifies mechanical property requirements for 7075-T6 extruded profiles: tensile strength ≥ 530 MPa, yield strength ≥ 460 MPa, elongation ≥ 6%, and a Brinell hardness (HB) reference value of 150.

[0045] As shown in Table 1, the aluminum alloy products obtained in Examples 1-3 of the present invention fully meet the performance and hardness requirements specified by national standards. While the performance of the aluminum alloy products obtained in the present invention is somewhat lower than that obtained in Comparative Example 1 through vertical quenching, this performance difference can be minimized by properly adjusting the process parameters of the present invention. In contrast to Comparative Example 2, the aluminum alloy products obtained in the present invention through single-stage aging rather than double-stage aging exhibit no significant performance differences.

[0046] In order to verify whether the aluminum alloy preparation method of the present invention will cause the aluminum alloy product to be over-burned if the bar heating temperature is set at the upper limit of the process in the aluminum bar preheating process, the 7075 aluminum alloy obtained in Example 1 was subjected to metallographic testing. The testing method is well known to those skilled in the art. Testing equipment: ZEISS AX10 Imager.A2m. The metallographic test results are shown in the figure below. Figure 4 As shown. Figure 4 It can be seen that the metallographic structure of the aluminum alloy product obtained in Example 1 of the present invention does not have overburning phenomenon.

[0047] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. An efficient preparation method for aluminum alloy products, characterized in that: The following steps are involved: Step S1, aluminum rod casting: aluminum ingots are cast to obtain aluminum alloy cast rods; Step S2, homogenization treatment: performing homogenization treatment on the aluminum alloy cast rod obtained in step S1 to obtain a homogenized aluminum alloy cast rod; Step S3, peeling the cast rod: peeling the homogenized aluminum alloy cast rod obtained in step S2 to obtain a peeled aluminum alloy cast rod; Step S4, preheating: preheating the peeled aluminum alloy cast rod, extrusion die and die barrel obtained in step S3 respectively to obtain preheated peeled aluminum alloy cast rod, extrusion die and die barrel; Step S5, extrusion: using a reverse extruder, the peeled aluminum alloy cast rod preheated in step S4 is extruded through a die in a die barrel to continuously extrude an unquenched aluminum alloy product; Step S6, traction: a traction machine clamps the unquenched aluminum alloy product in step S5 at the discharge port of the reverse extruder and continues to traction until the extrusion process is completed; Step S7, online quenching treatment: During the pulling process described in step S6, the unquenched aluminum alloy product is passed through a water tank for cooling to obtain a quenched aluminum alloy product; Step S8, straightening or leveling: straightening or leveling the aluminum alloy product after quenching in step S7 to obtain an unaged aluminum alloy product that meets the straightness requirement; Step S9, aging treatment: The unaged aluminum alloy product meeting the straightness requirements in step S8 is artificially aged: the heating temperature is 145-155° C., the holding time is 4-6 hours, and the product is air-cooled after being taken out of the furnace to obtain the final aluminum alloy product.

2. The efficient preparation method of aluminum alloy products according to claim 1, characterized in that: In step S1, the aluminum alloy cast rod includes the following components, calculated by mass percentage: Si≤0.4%, Fe≤0.5%, Cu 1.2%-2.0%, Mn≤0.3%, Mg 2.1%-2.9%, Cr 0.18%-0.28%, Zn 5.1%-6.1%, Ti≤0.2%, Zr+Ti≤0.25%, the total amount of other impurity elements ≤0.15%, and the balance is Al.

3. The efficient preparation method of aluminum alloy products according to claim 1, characterized in that: In step S2, the heating temperature of the homogenization treatment is 380-410°C, the holding time is 4-6 hours, and then the temperature is raised to 440-470°C, the holding time is 4-6 hours, and the product is air-cooled after being taken out of the furnace.

4. The efficient preparation method of aluminum alloy products according to claim 1, characterized in that: In step S3, the cast rod peeling is cold peeling of the cast rod, and the peeling thickness is 1 to 2.5 mm.

5. The efficient preparation method of aluminum alloy products according to claim 1, characterized in that: In step S4, the heating temperature of the peeled aluminum alloy cast rod is 430-470°C, the heating temperature of the extrusion die is 340-380°C, and the heating temperature of the die barrel is 340-380°C; The extrusion die is a reverse extrusion die with a working zone width of 5-7 mm. A guide groove is provided on the side of the working zone close to the aluminum alloy casting rod. The inclination angle of the guide groove side wall is 3°-8° and the width is 3-5 mm.

6. The efficient preparation method of aluminum alloy products according to claim 1, characterized in that: During the extrusion process of step S5, the discharge speed of the unquenched aluminum alloy product is 1 to 3 m / min.

7. The efficient preparation method of aluminum alloy products according to claim 1, characterized in that: During the pulling process in step S6, an infrared thermometer is used to monitor the product temperature at the extruder outlet. The horizontal distance between the infrared thermometer and the cooling water tank is no more than 400 mm. The temperature of the aluminum alloy product is 460-500°C.

8. The efficient preparation method of aluminum alloy products according to claim 1, characterized in that: The online quenching method in step S7 is pile water cooling, the cooling water temperature during the process is not higher than 45°C, and the temperature of the product after cooling is not higher than 100°C.

9. The efficient preparation method of aluminum alloy products according to claim 1, characterized in that: In step S7, the traction machine clamps the product on the side of the water tank close to the extruder and moves in the water tank, continuing the traction action until the extrusion process is completed. After the product is clamped by the traction machine, pile water cooling is started until the product is completely pulled out of the water tank.

10. An aluminum alloy product, characterized in that: The aluminum alloy product is prepared by the preparation method according to any one of claims 1 to 9, and has a tensile strength of ≥560 MPa, a yield strength of ≥500 MPa, an elongation of ≥7%, and a Brinell hardness HB of ≥150.

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