Preparation method of high-strength and high-conductivity aluminum alloy profile

Abstract

The invention discloses a preparation method of a high-strength and high-conductivity aluminum alloy profile, which comprises the following steps: 1) carrying out solution treatment on an aluminum alloy raw material to obtain a supersaturated solid solution; (2) the supersaturated solid solution is subjected to low-temperature extrusion treatment, and the aluminum alloy profile is obtained; and thirdly, the aluminum alloy profile is heated, and the high-strength and high-conductivity aluminum alloy profile is obtained. According to the method, hot extrusion is replaced by low-temperature extrusion, so that the aluminum alloy profile generates a remarkable cold hardening effect, the strength of the alloy is greatly improved, meanwhile, severe plastic deformation at the extrusion temperature generates a large number of intragranular dislocations, Mg and Si elements are promoted to be quickly and fully dispersed and separated out, the alloy generates a precipitation strengthening effect, and the conductivity is improved.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy materials, and specifically relates to a method for preparing high-strength, high-conductivity aluminum alloy profiles. Background Technology

[0002] Conductor rails are a crucial component of rail transit. They are rigid power transmission rails distributed parallel to the electrified railway tracks, transmitting electricity to the locomotive. Conductor rails are typically located on either side or in the middle of the track, and are also known as the third rail or power supply rail of rail transit systems. They significantly impact the high-speed operation and safety reliability of trains. Aluminum alloys are characterized by high specific strength and good electrical conductivity; therefore, conductor rails are primarily made of aluminum alloy profiles. Currently, the aluminum alloy profiles used for conductor rails are commonly 6063 or 6101 aluminum alloys, manufactured through extrusion and heat treatment processes.

[0003] Currently, the aluminum alloy profiles used to manufacture conductive rails mainly employ a semi-continuous casting, hot extrusion, (solution) quenching, and aging process. Due to limitations in existing production processes, the alloy's strength is primarily ensured through aging strengthening, making significant breakthroughs difficult. The highest reported strength for conductive rail profiles is 298 MPa, but the conductivity is only 50% IACS. When the conductivity is increased to 55% IACS, the strength drops below 250 MPa, making it difficult to simultaneously achieve high strength and high conductivity. In view of these problems, there is an urgent need in this field to develop a production method for large-size, high-strength, high-conductivity aluminum alloy conductive rail profiles to address the issues present in existing technologies. Summary of the Invention

[0004] To address the manufacturing challenges of existing large-size, high-strength, high-conductivity aluminum alloy conductive rail profiles, this invention proposes a method for preparing high-strength, high-conductivity aluminum alloy profiles. The above objective can be achieved through the following technical solutions: A method for preparing a high-strength, high-conductivity aluminum alloy profile includes the following steps: Step 1) The aluminum alloy raw material is subjected to solution treatment to obtain a supersaturated solid solution; Step 2) The supersaturated solid solution is subjected to low-temperature extrusion treatment. The extrusion ratio λ is 5~8, the temperature of the saturated solid solution is 130~150℃, the temperature of the extrusion cylinder is 150~180℃, the temperature of the die is 120~140℃, and the extrusion speed is 2~3m / min; thus, an aluminum alloy profile is obtained. Step 3) The aluminum alloy profile is kept at a temperature of 160~200℃ for 8~15h to obtain the high-strength and high-conductivity aluminum alloy profile. Optionally, the aluminum alloy raw material in step one) is an aluminum alloy ingot containing La and Ce; Optionally, the aluminum alloy raw material in step one) is an aluminum alloy ingot, and the aluminum alloy ingot contains the following elements by mass fraction: Mg 0.5-0.7%, Si 0.4-0.6%, Fe 0.15-0.2%, Cu 0.1-0.3%, La 0.01-0.05%, Ce 0.01-0.05%, B 0.01-0.05%, impurity elements ≤0.02%, the remainder is aluminum.

[0005] Optionally, the aluminum alloy ingot in step one) is prepared by the following method: batching and melting, then degassing and filtering the melt during casting; then semi-continuous round ingot casting is carried out using an air-lubricating crystallizer, and the aluminum alloy ingot is obtained.

[0006] Optionally, in step one), the heating temperature of the solution treatment is 500~550℃, the holding time is 3~5h, and after the holding time is completed, the solution is quenched in water.

[0007] Optionally, in step one, the aluminum alloy raw material is a short bar of 400-600mm; after the solution treatment is completed, the segregation layer and oxide scale on the surface of the supersaturated solid solution are removed.

[0008] Optionally, a lubricant is sprayed onto the surface of the supersaturated solid solution before the low-temperature extrusion treatment; The lubricant contains at least one of mineral oil, beeswax, fatty acid, and fatty acid alcohol.

[0009] Optionally, step two further includes stretching, straightening, and cutting the aluminum alloy profile.

[0010] Optionally, in the low-temperature extrusion process, the extrusion ratio λ is 6, the saturated solid solution temperature is 150°C, the extrusion barrel temperature is 160°C, the die temperature is 140°C, and the extrusion speed is 3 m / min.

[0011] The present invention also proposes a high-strength, high-conductivity aluminum alloy profile prepared by the above-mentioned preparation method.

[0012] This invention also proposes the application of the aforementioned high-strength, high-conductivity aluminum alloy profiles in the manufacture of conductive rails for rail transit.

[0013] Compared with the prior art, the present invention has the following outstanding advantages: This invention uses low-temperature extrusion instead of hot extrusion, which produces a significant cold work hardening effect in aluminum alloy profiles, greatly improving the strength of the alloy. At the same time, the intense plastic deformation at the extrusion temperature generates a large number of intragranular dislocations, which promotes the rapid and sufficient dispersion precipitation of Mg and Si elements, resulting in precipitation strengthening effect and improved conductivity of the alloy. The present invention combines deformation aging during the extrusion process with secondary aging of the profile to maximize the precipitation strengthening effect of Mg and Si elements and minimize their adverse effects on the electrical conductivity of the alloy. The rare earth elements La and Ce of this invention reduce the solid solubility of trace elements in the alloy, forming regular inclusion phases along the grain boundaries, thereby improving the electrical conductivity of the alloy. Detailed Implementation

[0014] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0015] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0016] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0017] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0018] The specific implementation steps of the process method of this invention are as follows: Step 1) Casting Aluminum Alloy Ingots: Aluminum alloy round ingots are prepared by batching and smelting, refining the melt, and semi-continuous casting according to the alloy composition. Rare earth elements and boron are added during smelting, and the melt is degassed and filtered online during casting. Using an air-lubricating crystallizer for semi-continuous round ingot casting can produce aluminum ingots with a small segregation layer thickness and good surface quality.

[0019] The aluminum ingots are then subjected to solution treatment: the cast aluminum round ingots are cut into short bars with a length of 400-600 mm, and the short bars are then subjected to solution treatment at a heating temperature of 500-550℃ for 3-5 hours. The short bars are then quenched in water. This solution quenching process allows the alloying elements Mg and Si to fully dissolve back into the matrix, forming a supersaturated solid solution. After solution treatment, the short bars are machined to remove the surface segregation layer and oxide scale, reducing structural defects in the extruded profiles.

[0020] Step 2) Extrusion: The short bars from the car body are cryogenically extruded using an extrusion device. The extrusion ratio λ is controlled at 5-8. The heating temperature of the short bars after solution treatment is 130-150℃, the extrusion barrel temperature is 150-180℃, and the die temperature is 120-140℃. Before extrusion, a lubricant composed of mineral oil, beeswax, fatty acids, and fatty acid alcohols is sprayed onto the surface of the short bars. The extrusion speed is controlled at 2-3 m / min. During the extrusion process, the aluminum alloy undergoes severe plastic deformation, promoting the rapid dispersion and precipitation of some Mg and Si elements. At the same time, due to the low extrusion temperature, the aluminum alloy profile also achieves a significant work hardening effect. After the extruded conductive rail profile cools naturally to below 50℃, the profile is stretched and straightened to eliminate the residual stress generated during extrusion. Subsequently, the profile is cut to length according to product requirements to obtain conductive rail workpieces of specific lengths.

[0021] Step 3) Aging Treatment: The cut-to-length workpiece is placed in an aging furnace for aging treatment at a temperature of 160~200℃ for 8~15 hours. After aging treatment, the remaining Mg and Si elements dissolved in the aluminum alloy matrix continue to precipitate more fully as dispersed β"(Mg5Si6) and β'(Mg9Si5) phases, further improving the strength of the profile. Due to the reduction in alloy lattice distortion after aging, the conductivity of the profile is also significantly improved.

[0022] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0023] In the embodiments, the raw materials for smelting aluminum alloy ingots are: 99.7% pure aluminum, 99.9% pure magnesium, aluminum-silicon master alloy, aluminum-copper master alloy, aluminum rare earth (La, Ce) master alloy, and aluminum-boron master alloy.

[0024] Example 1 Step 1: Perform batching and smelting, melt refining, and semi-continuous casting to prepare aluminum alloy round ingots. The alloy composition of the aluminum alloy round ingots is: Mg 0.55%, Si 0.48%, Fe 0.17%, Cu 0.15%, La 0.03%, Ce 0.04%, B 0.02%, with the remainder being Al and other unavoidable impurity elements. The content of each unavoidable impurity element is ≤0.005%, and the total amount of other unavoidable impurity elements is ≤0.02%.

[0025] Step 2: Cut the round ingot into short bars with a length of 500mm, perform solution treatment at 520℃, hold for 5 hours, and then quench to form a supersaturated solid solution.

[0026] Step 3: Remove the surface segregation layer and oxide scale defects from the short rods after solution treatment by machining.

[0027] Step 4: Perform low-temperature extrusion on the short bars after the car body, with an extrusion ratio λ of 6. Apply lubricant to the surface of the short bars before extrusion. Control the temperature of the short bars at 150℃, the extrusion barrel temperature at 160℃, and the die temperature at 140℃, and control the extrusion speed at 3m / min.

[0028] Step 5: Stretch and straighten the extruded profile to eliminate residual stress generated during extrusion. Cut the profile to length according to product requirements to obtain conductive rail workpieces of a specific length.

[0029] Step Six: The sized workpiece is subjected to aging treatment at 180℃ for 12 hours. Testing revealed that the obtained conductive rail profile has a tensile strength of 288MPa, a yield strength of 253MPa, an elongation ≥12.6%, and a conductivity of 57.8% IACS.

[0030] Example 2 Step 1: Perform batching and smelting, melt refining, and semi-continuous casting to prepare aluminum alloy round ingots. The alloy composition of the aluminum alloy round ingots is: Mg 0.68%, Si 0.57%, Fe 0.18%, Cu 0.22%, La 0.03%, Ce 0.03%, B 0.03%, with the remainder being Al and other unavoidable impurity elements. The content of each unavoidable impurity element is ≤0.005%, and the total amount of other unavoidable impurity elements is ≤0.02%.

[0031] Step 2: Cut the round ingot into short bars with a length of 500mm, perform solution treatment at 520℃, hold for 5 hours, and then quench to form a supersaturated solid solution.

[0032] Step 3: Remove the surface segregation layer and oxide scale defects from the short rods after solution treatment by machining.

[0033] Step 4: Perform low-temperature extrusion on the short bars after the car body, with an extrusion ratio λ of 6. Apply lubricant to the surface of the short bars before extrusion. Control the temperature of the short bars at 150℃, the extrusion cylinder temperature at 150℃, and the die temperature at 140℃, and control the extrusion speed at 3m / min.

[0034] Step 5: Stretch and straighten the extruded profile to eliminate residual stress generated during extrusion. Cut the profile to length according to product requirements to obtain conductive rail workpieces of a specific length.

[0035] Step Six: The sized workpiece is subjected to aging treatment at 185℃ for 12 hours. Testing revealed that the obtained conductive rail profile has a tensile strength of 292 MPa, a yield strength of 258 MPa, an elongation ≥11%, and a conductivity of 57.3% IACS.

[0036] Example 3 Step 1: Perform batching and smelting, melt refining, and semi-continuous casting to prepare aluminum alloy round ingots. The alloy composition of the aluminum alloy round ingots is: Mg 0.53%, Si 0.58%, Fe 0.18%, Cu 0.12%, La 0.05%, Ce 0.04%, B 0.023%, with the remainder being Al and other unavoidable impurity elements. The content of each unavoidable impurity element is ≤0.005%, and the total amount of other unavoidable impurity elements is ≤0.02%.

[0037] Step 2: Cut the round ingot into short bars with a length of 500mm, perform solution treatment at 520℃, hold for 5 hours, and then quench to form a supersaturated solid solution.

[0038] Step 3: Remove the surface segregation layer and oxide scale defects from the short rods after solution treatment by machining.

[0039] Step 4: Perform low-temperature extrusion on the short bars after the car body, with an extrusion ratio λ of 6. Apply lubricant to the surface of the short bars before extrusion. Control the temperature of the short bars at 155℃, the extrusion barrel temperature at 160℃, and the die temperature at 140℃, and control the extrusion speed at 3m / min.

[0040] Step 5: Stretch and straighten the extruded profile to eliminate residual stress generated during extrusion. Cut the profile to length according to product requirements to obtain conductive rail workpieces of a specific length.

[0041] Step Six: The sized workpiece is subjected to aging treatment at 190℃ for 9 hours. Testing revealed that the obtained conductive rail profile has a tensile strength of 282 MPa, a yield strength of 255 MPa, an elongation ≥11.6%, and a conductivity of 57.6% IACS.

[0042] Example 4 Step 1: Perform batching and smelting, melt refining, and semi-continuous casting to prepare aluminum alloy round ingots. The alloy composition of the aluminum alloy round ingots is: Mg 0.69%, Si 0.42%, Fe 0.18%, Cu 0.18%, La 0.03%, Ce 0.03%, B 0.036%, with the remainder being Al and other unavoidable impurity elements. The content of each unavoidable impurity element is ≤0.005%, and the total amount of other unavoidable impurity elements is ≤0.02%.

[0043] Step 2: Cut the round ingot into short bars with a length of 500mm, perform solution treatment at 520℃, hold for 5 hours, and then quench to form a supersaturated solid solution.

[0044] Step 3: Remove the surface segregation layer and oxide scale defects from the short rods after solution treatment by machining.

[0045] Step 4: Perform low-temperature extrusion on the short bars after the car body, with an extrusion ratio λ of 6. Apply lubricant to the surface of the short bars before extrusion. Control the temperature of the short bars at 150℃, the extrusion barrel temperature at 170℃, and the die temperature at 140℃, and control the extrusion speed at 3m / min.

[0046] Step 5: Stretch and straighten the extruded profile to eliminate residual stress generated during extrusion. Cut the profile to length according to product requirements to obtain conductive rail workpieces of a specific length.

[0047] Step Six: The sized workpiece is subjected to aging treatment at 190℃ for 9 hours. Testing revealed that the obtained conductive rail profile has a tensile strength of 285MPa, a yield strength of 261MPa, an elongation ≥10.8%, and a conductivity of 57.5% IACS.

[0048] Example 5 Step 1: Perform batching and smelting, melt refining, and semi-continuous casting to prepare aluminum alloy round ingots. The alloy composition of the aluminum alloy round ingots is: Mg 0.54%, Si 0.48%, Fe 0.18%, Cu 0.15%, La 0.03%, Ce 0.03%, B 0.02%, with the remainder being Al and other unavoidable impurity elements. The content of each unavoidable impurity element is ≤0.005%, and the total amount of other unavoidable impurity elements is ≤0.02%.

[0049] Step 2: Cut the round ingot into short bars with a length of 500mm, perform solution treatment at 520℃, hold for 5 hours, and then quench to form a supersaturated solid solution.

[0050] Step 3: Remove the surface segregation layer and oxide scale defects from the short rods after solution treatment by machining.

[0051] Step 4: Perform low-temperature extrusion on the short bars after the car body, with an extrusion ratio λ of 6. Apply lubricant to the surface of the short bars before extrusion. Control the temperature of the short bars at 150℃, the extrusion barrel temperature at 160℃, and the die temperature at 140℃, and control the extrusion speed at 2m / min.

[0052] Step 5: Stretch and straighten the extruded profile to eliminate residual stress generated during extrusion. Cut the profile to length according to product requirements to obtain conductive rail workpieces of a specific length.

[0053] Step Six: The sized workpiece is subjected to aging treatment at 180℃ for 12 hours. Testing revealed that the obtained conductive rail profile has a tensile strength of 282 MPa, a yield strength of 250 MPa, an elongation ≥13.2%, and a conductivity of 57.9% IACS.

[0054] Comparative Example 1 Step 1: Perform batching and smelting, melt refining, and semi-continuous casting to prepare aluminum alloy round ingots. The alloy composition of the aluminum alloy round ingots is: Mg 0.61%, Si 0.44%, Fe 0.17%, Cu 0.15%, La 0.02%, Ce 0.02%, B 0.02%, with the remainder being Al and other unavoidable impurity elements. The content of each unavoidable impurity element is ≤0.005%, and the total amount of other unavoidable impurity elements is ≤0.02%.

[0055] Step 2: Cut the round ingot into short bars with a length of 500mm, and then remove the surface segregation layer and oxide scale defects by machining.

[0056] Step 3: Hot extrusion is performed on the short bars after the car body, with an extrusion ratio λ of 6. The heating temperature of the short bars is 460℃, the extrusion cylinder temperature is 460℃, the die temperature is 450℃, the extrusion speed is 5m / min, and the profile is cooled by strong air after extrusion.

[0057] Step 4: After the profile cools to below 50°C, perform stretching and straightening to eliminate residual thermal stress generated during extrusion.

[0058] Step 6: Cut the profile to length according to product requirements to obtain conductive rail workpieces of a specific length.

[0059] Step 7: The sized workpiece is subjected to aging treatment at 190℃ for 12 hours. Testing revealed that the obtained conductive rail profile has a tensile strength of 224 MPa, a yield strength of 197 MPa, an elongation of 14.3%, and a conductivity of 57.2% IACS.

[0060] Comparative Example 2 Step 1: Perform batching and smelting, melt refining, and semi-continuous casting to prepare aluminum alloy round ingots. The alloy composition of the aluminum alloy round ingots is: Mg 0.46%, Si 0.37%, Fe 0.16%, Cu 0.18%, La 0.02%, Ce 0.02%, B 0.03%, with the remainder being Al and other unavoidable impurity elements. The content of each unavoidable impurity element is ≤0.005%, and the total amount of other unavoidable impurity elements is ≤0.02%.

[0061] Step 2: Cut the round ingot into short bars with a length of 500mm, perform solution treatment at 520℃, hold for 5 hours, and then quench to form a supersaturated solid solution.

[0062] Step 3: Remove the surface segregation layer and oxide scale defects from the short rods after solution treatment by machining.

[0063] Step 4: Perform low-temperature extrusion on the short bars after the car body, with an extrusion ratio λ of 6. Apply lubricant to the surface of the short bars before extrusion. Control the temperature of the short bars at 150℃, the extrusion barrel temperature at 160℃, and the die temperature at 140℃, and control the extrusion speed at 3m / min.

[0064] Step 5: Stretch and straighten the extruded profile to eliminate residual stress generated during extrusion. Cut the profile to length according to product requirements to obtain conductive rail workpieces of a specific length.

[0065] Step Six: The sized workpiece is subjected to aging treatment at 180℃ for 12 hours. Testing revealed that the obtained conductive rail profile has a tensile strength of 266MPa, a yield strength of 231MPa, an elongation ≥12.8%, and a conductivity of 58.1% IACS.

[0066] Comparative Example 3 Step 1: Perform batching and smelting, melt refining, and semi-continuous casting to prepare aluminum alloy round ingots. The alloy composition of the aluminum alloy round ingots is: Mg 0.46%, Si 0.37%, Fe 0.16%, Cu 0.18%, La 0.02%, Ce 0.02%, B 0.03%, with the remainder being Al and other unavoidable impurity elements. The content of each unavoidable impurity element is ≤0.005%, and the total amount of other unavoidable impurity elements is ≤0.02%.

[0067] Step 2: Cut the round ingot into short bars with a length of 500mm, perform solution treatment at 520℃, hold for 5 hours, and then quench to form a supersaturated solid solution.

[0068] Step 3: Remove the surface segregation layer and oxide scale defects from the short rods after solution treatment by machining.

[0069] Step 4: Perform low-temperature extrusion on the short bars after the car body, with an extrusion ratio λ of 6. Apply lubricant to the surface of the short bars before extrusion. Control the temperature of the short bars at 150℃, the extrusion barrel temperature at 160℃, and the die temperature at 140℃, and control the extrusion speed at 3m / min.

[0070] Step 5: Stretch and straighten the extruded profile to eliminate residual stress generated during extrusion. Cut the profile to length according to product requirements to obtain conductive rail workpieces of a specific length.

[0071] Step Six: The sized workpiece is subjected to aging treatment at 180℃ for 12 hours. Testing revealed that the obtained conductive rail profile has a tensile strength of 266MPa, a yield strength of 231MPa, an elongation ≥12.8%, and a conductivity of 58.1% IACS.

[0072] Comparative Example 4 Step 1: Perform batching and smelting, melt refining, and semi-continuous casting to prepare aluminum alloy round ingots. The alloy composition of the aluminum alloy round ingots is: Mg 0.76%, Si 0.62%, Fe 0.17%, Cu 0.2%, La 0.03%, Ce 0.02%, B 0.02%, with the remainder being Al and other unavoidable impurity elements. The content of each unavoidable impurity element is ≤0.005%, and the total amount of other unavoidable impurity elements is ≤0.02%.

[0073] Step 2: Cut the round ingot into short bars with a length of 500mm, perform solution treatment at 520℃, hold for 5 hours, and then quench to form a supersaturated solid solution.

[0074] Step 3: Remove the surface segregation layer and oxide scale defects from the short rods after solution treatment by machining.

[0075] Step 4: Perform low-temperature extrusion on the short bars after the car body, with an extrusion ratio λ of 6. Apply lubricant to the surface of the short bars before extrusion. Control the temperature of the short bars at 150℃, the extrusion barrel temperature at 160℃, and the die temperature at 140℃, and control the extrusion speed at 3m / min.

[0076] Step 5: Stretch and straighten the extruded profile to eliminate residual stress generated during extrusion. Cut the profile to length according to product requirements to obtain conductive rail workpieces of a specific length.

[0077] Step Six: The sized workpiece is subjected to aging treatment at 180℃ for 12 hours. Testing revealed that the obtained conductive rail profile has a tensile strength of 298MPa, a yield strength of 263MPa, an elongation ≥9.8%, and a conductivity of 56.4% IACS.

[0078] Comparative Example 5 Aluminum alloy round ingots are prepared by batching and smelting, melt refining, and semi-continuous casting. The alloy composition of the aluminum alloy round ingots is as follows: Mg 0.56%, Si 0.52%, Fe 0.15%, Cu 0.18%, La 0.03%, Ce 0.04%, B 0.03%, with the remainder being Al and other unavoidable impurity elements. The content of each unavoidable impurity element is ≤0.005%, and the total amount of other unavoidable impurity elements is ≤0.02%.

[0079] Step 2: Cut the round ingot into short bars with a length of 500mm, perform solution treatment at 520℃, hold for 5 hours, and then quench to form a supersaturated solid solution.

[0080] Step 3: Remove the surface segregation layer and oxide scale defects from the short rods after solution treatment by machining.

[0081] Step 4: Perform low-temperature extrusion on the short bars after the car body, with an extrusion ratio λ of 6. Apply lubricant to the surface of the short bars before extrusion. Control the temperature of the short bars at 200℃, the extrusion cylinder at 200℃, and the die at 180℃, and control the extrusion speed at 3m / min.

[0082] Step 5: Stretch and straighten the extruded profile to eliminate residual stress generated during extrusion. Cut the profile to length according to product requirements to obtain conductive rail workpieces of a specific length.

[0083] Step Six: The sized workpiece is subjected to aging treatment at 180℃ for 12 hours. Testing revealed that the obtained conductive rail profile has a tensile strength of 258MPa, a yield strength of 235MPa, an elongation ≥15.6%, and a conductivity of 58.5% IACS.

[0084] Comparative Example 6 Step 1: Perform batching and smelting, melt refining, and semi-continuous casting to prepare aluminum alloy round ingots. The alloy composition of the aluminum alloy round ingots is: Mg 0.58%, Si 0.51%, Fe 0.16%, Cu 0.25%, B 0.04%, with the remainder being Al and other unavoidable impurity elements. The content of each unavoidable impurity element is ≤0.005%, and the total amount of other unavoidable impurity elements is ≤0.02%.

[0085] Step 2: Cut the round ingot into short bars with a length of 500mm, perform solution treatment at 520℃, hold for 5 hours, and then quench to form a supersaturated solid solution.

[0086] Step 3: Remove the surface segregation layer and oxide scale defects from the short rods after solution treatment by machining.

[0087] Step 4: Perform low-temperature extrusion on the short bars after the car body, with an extrusion ratio λ of 6. Apply lubricant to the surface of the short bars before extrusion. Control the temperature of the short bars at 150℃, the extrusion barrel temperature at 160℃, and the die temperature at 140℃, and control the extrusion speed at 3m / min.

[0088] Step 5: Stretch and straighten the extruded profile to eliminate residual stress generated during extrusion. Cut the profile to length according to product requirements to obtain conductive rail workpieces of a specific length.

[0089] Step Six: The sized workpiece is subjected to aging treatment at 180℃ for 12 hours. Testing revealed that the obtained conductive rail profile has a tensile strength of 276 MPa, a yield strength of 254 MPa, an elongation ≥12.2%, and a conductivity of 56.8% IACS.

[0090] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a high-strength, high-conductivity aluminum alloy profile, characterized in that, Includes the following steps: Step 1) The aluminum alloy raw material is subjected to solution treatment to obtain a supersaturated solid solution; Step 2) The supersaturated solid solution is subjected to low-temperature extrusion treatment, wherein the extrusion ratio λ is 5~8, the temperature of the saturated solid solution is 130~150℃, the temperature of the extrusion cylinder is 150~180℃, the temperature of the die is 120~140℃, and the extrusion speed is 2~3m / min; to obtain aluminum alloy profiles; Step 3) The aluminum alloy profile is kept at a temperature of 160~200℃ for 8~15h to obtain the high-strength and high-conductivity aluminum alloy profile.

2. The method for preparing high-strength, high-conductivity aluminum alloy profiles according to claim 1, characterized in that, The aluminum alloy raw material in step one) is an aluminum alloy ingot, which contains La and Ce. Preferably, the aluminum alloy ingot contains the following elements in mass fraction: Mg 0.5-0.7%, Si 0.4-0.6%, Fe 0.15-0.2%, Cu 0.1-0.3%, La 0.01-0.05%, Ce 0.01-0.05%, B 0.01-0.05%, impurity elements ≤0.02%, the remainder is aluminum.

3. The method for preparing high-strength, high-conductivity aluminum alloy profiles according to claim 1, characterized in that, The aluminum alloy ingot in step one) is prepared by the following method: batching and melting, then degassing and filtering the melt during casting; then semi-continuous round ingot casting is carried out using an air-lubricating crystallizer.

4. The method for preparing high-strength, high-conductivity aluminum alloy profiles according to claim 1, characterized in that, In step one), the heating temperature for the solution treatment is 500~550℃, the holding time is 3~5h, and after the holding time is completed, the solution is quenched in water.

5. The method for preparing high-strength, high-conductivity aluminum alloy profiles according to claim 1, characterized in that, In step one, the aluminum alloy raw material is a short bar of 400~600mm; after the solution treatment, the segregation layer and oxide scale on the surface of the supersaturated solid solution are removed.

6. The method for preparing high-strength, high-conductivity aluminum alloy profiles according to claim 1, characterized in that, Lubricant is sprayed onto the surface of the supersaturated solid solution before the low-temperature extrusion treatment; The lubricant contains at least one of mineral oil, beeswax, fatty acid, and fatty acid alcohol.

7. The method for preparing high-strength, high-conductivity aluminum alloy profiles according to claim 1, characterized in that, Step two also includes stretching, straightening and cutting the aluminum alloy profile.

8. The method for preparing high-strength, high-conductivity aluminum alloy profiles according to claim 1, characterized in that, In the low-temperature extrusion process, the extrusion ratio λ is 6, the saturated solid solution temperature is 150℃, the extrusion barrel temperature is 160℃, the die temperature is 140℃, and the extrusion speed is 3m / min.

9. The high-strength, high-conductivity aluminum alloy profile prepared by the preparation method according to any one of claims 1 to 7.

10. The application of the high-strength, high-conductivity aluminum alloy profile as described in claim 9 in the manufacture of conductive rails for rail transit.