Processing technology of light-weight high-hardness high-strength aluminum profile

Abstract

The invention discloses a processing technology of a lightweight high-hardness high-strength aluminum profile, and relates to the technical field of aluminum alloy processing. According to the method, the 7050 aluminum alloy profile is smelted, the extra Si element is added in the smelting process, the content of the Si element in the 7050 aluminum alloy sheet is increased, the metastable Al-Si phase in the alloy is increased, meanwhile, nano TiC is added, the prepared aluminum alloy profile is effectively refined, then multi-stage artificial aging treatment is adopted, more energy is provided for nucleation of a precipitated phase in the aluminum alloy, and the aluminum alloy can be effectively refined. And finally, the recast 7050 aluminum alloy profile is subjected to anodic oxidation surface treatment, a hard compact oxidation film is formed on the surface of the aluminum alloy profile, the porosity of the surface of the aluminum profile is reduced, the hardness of the aluminum profile is enhanced, and the service life of the aluminum profile is prolonged. The aluminum profile prepared through the method is high in strength and hardness, and cracks are effectively reduced in the automobile lightweight application process.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum alloy processing, and in particular to a processing technology for lightweight, high-hardness and high-strength aluminum profiles. Background Art

[0002] With the rapid development of industries such as aerospace, rail transit, new energy vehicles, mobile phones, and laptops, the demand for high-performance aluminum alloy materials is increasing. These industries require materials to be lightweight while having high strength and high toughness. The 7 series aluminum alloy contains alloying elements such as Zn and Mg, and is an Al-Zn-Mg-Cu alloy. Due to its extremely high strength, it is used in aerospace and military fields. In the civilian field, the 7 series aluminum alloy is also used in the manufacture of automobile bumpers and housings of consumer electronic devices. In the military field, 7 series aluminum alloys are usually required to have high strength, fracture toughness and corrosion resistance, while in the consumer electronics field, 7 series materials are more required to have high strength and corrosion resistance. However, during the billet making process, 7050 aluminum alloy is prone to high alloying degree and wide crystallization temperature range, so it is difficult to melt and cast, which easily leads to coarse grain boundary eutectic structure and dendrite segregation, and is prone to cracking during subsequent processing. Therefore, it is necessary to further optimize and improve the composition and processing technology of 7050 aluminum alloy profiles to optimize the performance of 7050 aluminum alloy profiles. Summary of the invention

[0003] The purpose of the present invention is to provide a processing technology for lightweight, high-hardness and high-strength aluminum profiles to solve the problems existing in the prior art.

[0004] In order to solve the above technical problems, the present invention provides the following technical solutions: a processing technology for lightweight, high-hardness and high-strength aluminum profiles, the processing technology comprising the following steps: (1) According to the chemical composition and content of 7050 aluminum alloy, the alloy is melted at 750-800°C, silicon powder and nano-TiC with a particle size of 50-80 nm are added after melting, and the alloy is stirred evenly to obtain an initial liquid; the chemical composition of the initial liquid alloy is 6.14Zn, 2.32Mg, 1.42Cu, 0.54Ti, 0.30Mn, 0.15Cr, 0.11Fe, and 0.25Si in mass fraction; (2) The alloy liquid in step (1) is refined, deslagging, degassing, stirring and deslagging in a holding furnace, and then degassing with argon gas and filtering with a ceramic filter plate online to obtain an alloy refined liquid; (3) casting the alloy refined liquid obtained in step (2) using a semi-continuous casting method to obtain an ingot; (4) Heat the ingot to 420-460℃, the mold to 430-470℃, and the extrusion barrel to 420-450℃; start extrusion after the temperature reaches the standard; control the extrusion outlet speed to 2.5-3.5m / min; control the extrusion outlet temperature to 470-490℃; perform online water quenching at the extrusion outlet, the water temperature is 20-40℃; cool to below 50℃; after extrusion, straighten the extruded part, and the straightening stretching amount is 0.5-0.8%; (5) sawing the straightened plate into the required length and performing solid solution treatment on the aluminum alloy profile; (6) After solution treatment, four-level artificial aging treatment is carried out; (7) After the four-level artificial aging treatment, the aluminum alloy profile is hard anodized to obtain a lightweight, high-hardness and high-strength aluminum profile.

[0005] Furthermore, the solution treatment in step (5) is to heat the aluminum alloy profile to 465-470°C, keep the temperature for 35-55 minutes, and then quench in 20-40°C water after the temperature is kept.

[0006] Furthermore, the four-stage artificial aging treatment in step (6) includes a first stage of high temperature aging treatment, a second stage of low temperature aging treatment, a third stage of high temperature aging treatment, and a fourth stage of low temperature aging treatment.

[0007] Furthermore, the first stage of high temperature aging treatment is to heat the aluminum alloy profile to 180-190°C, keep it warm for 10-12 hours, and air cool it to room temperature; the second stage of low temperature aging treatment is to heat it to 125-135°C, keep it warm for 10-12 hours, and air cool it to room temperature; the third stage of high temperature aging treatment is to heat it to 165-175°C, keep it warm for 10-12 hours, and air cool it to room temperature; the fourth stage of low temperature aging treatment is to heat it to 105-115°C, keep it warm for 10-12 hours, and air cool it to room temperature.

[0008] Furthermore, the hard anodizing treatment in step (7) is to pre-treat the aluminum alloy profile, prepare an electrolyte, and then conduct the hard anodizing treatment at a voltage of 50-120 V and a current density of 0.6-4.5 A / dm 2 Under the conditions of , process for 80~90min.

[0009] Furthermore, the aluminum alloy profile pretreatment includes drilling and tapping on the aluminum alloy profile, connecting wires, and polishing the test piece with sandpaper of No. 700-1100 in sequence; after polishing, it is treated with deionized water, anhydrous ethanol, and acetone in sequence, and finally dried with hot air.

[0010] Furthermore, the electrolyte is a H2SO4 solution with a mass fraction of 170-180 g / L and a solution temperature of -3-5°C.

[0011] Compared with the prior art, the beneficial effects achieved by the present invention are: The present invention provides a processing technology for a lightweight, high-hardness and high-strength aluminum profile. The prepared aluminum profile is lightweight while improving the hardness and strength of the aluminum profile.

[0012] The present invention melts the 7050 aluminum alloy, adds additional Si elements during the melting process, increases the content of Si elements in the aluminum profile, increases the metastable Al-Si phase in the alloy, further assists the formation of aluminum oxide crystals, promotes the stability of aluminum oxide, improves the corrosion resistance of the aluminum alloy, and provides a low melting point phase for selective laser melting of the aluminum alloy in the later stage, effectively reduces cracks caused by the laser welding process of the 7050 aluminum alloy, and enables the aluminum profile to play a better application effect in the application of automobile lightweighting. At the same time, nano-TiC is added to the aluminum alloy, and a large number of effective heterogeneous cores are provided for the aluminum alloy during the formation of the 7050 aluminum alloy, so that the liquid pool is divided more densely and evenly during the crystallization of aluminum, and the second phase distributed along the grain boundary generated by the eutectic reaction becomes fine and even, and finally an aluminum alloy profile with a high degree of refinement is obtained, and the hardness of the aluminum alloy profile is effectively improved.

[0013] Secondly, multi-stage artificial aging treatment is used to provide more energy for the nucleation of precipitation phases in the aluminum alloy, and sufficient time is reserved for the growth of the nucleus. The formed precipitation phase is small and uniform, which effectively hinders the movement of dislocations in the aluminum alloy, improves the strength of the material, and forms a stable structure, effectively resisting the damage caused by corrosive substances to the material. Finally, the recast 7050 aluminum alloy profile is anodized to form a hard and dense oxide film on the surface of the aluminum alloy profile, reduce the surface porosity of the aluminum material, enhance the hardness of the aluminum material, and extend the service life of the aluminum material. DETAILED DESCRIPTION

[0014] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0015] In order to more clearly illustrate the method provided by the present invention, the following examples are used to describe in detail the various index testing methods of the lightweight, high-hardness, and high-strength aluminum profiles prepared in the following examples are as follows: Mechanical properties test: The mechanical properties of the aluminum alloy profiles prepared in Examples 1-3 and Comparative Examples 1-6 were tested using a SUN10 electronic universal testing machine. Three groups of parallel samples were taken for each state and the average value was taken. Stress corrosion resistance test: According to ASTMG44-99, the stress corrosion resistance of the aluminum alloy profiles prepared in Examples 1-3 and Comparative Examples 1-6 was tested; Welding performance test: According to GB / T19869.2-2012, the welding performance of the aluminum alloy profiles prepared in Examples 1-3 and Comparative Examples 1-6 was tested. Example 1

[0016] (1) According to the chemical composition and content of 7050 aluminum alloy, the alloy is melted at 760°C, silicon powder and nano-TiC with a particle size of 60 nm are added after melting, and the alloy is stirred evenly to obtain an initial liquid; the chemical composition of the initial liquid alloy is 6.14Zn, 2.32Mg, 1.42Cu, 0.54Ti, 0.30Mn, 0.15Cr, 0.11Fe, and 0.25Si in mass fraction; (2) The alloy liquid in step (1) is refined, deslagging, degassing, stirring and deslagging in a holding furnace, and then degassing with argon gas and filtering with a ceramic filter plate online to obtain an alloy refined liquid; (3) casting the alloy refined liquid obtained in step (2) using a semi-continuous casting method to obtain an ingot; (4) The ingot is heated to 420°C, the mold is heated to 430°C, and the extrusion barrel is heated to 420°C; extrusion is started after the temperature reaches the standard; the extrusion outlet speed is controlled to 2.5m / min; the extrusion outlet temperature is controlled to 470°C; online water quenching is performed at the extrusion outlet, the water temperature is 30°C; and the extrusion is cooled to below 50°C; after extrusion, the extruded part is straightened, and the straightening stretching amount is 0.7%; (5) Saw the straightened plate into the required length, heat the aluminum alloy profile to 465°C, keep it warm for 35 minutes, and then quench it in 30°C water; (6) After solution treatment, heat the aluminum alloy profile to 180°C, keep it warm for 10 h, and air cool it to room temperature; then heat it to 125°C, keep it warm for 10 h, and air cool it to room temperature; then heat it to 165°C, keep it warm for 10 h, and air cool it to room temperature; then heat it to 105°C, keep it warm for 10 h, and air cool it to room temperature; (7) After the four-stage artificial aging treatment, holes were drilled and tapped on the aluminum alloy profiles, wires were connected, and the test pieces were polished with sandpapers of 700 to 1100 in sequence; after polishing, they were treated with deionized water, anhydrous ethanol, and acetone in sequence, and then dried with hot air. Then, a H2SO4 solution with a mass fraction of 180 g / L was prepared at a solution temperature of -5 °C, at a voltage of 80 V and a current density of 3 A / dm 2 Under the conditions, the aluminum alloy profile was processed for 80 minutes, and finally a lightweight, high-hardness and high-strength aluminum profile was produced. Example 2

[0017] (1) According to the chemical composition and content of 7050 aluminum alloy, the alloy is melted at 760°C, silicon powder and nano-TiC with a particle size of 60 nm are added after melting, and the alloy is stirred evenly to obtain an initial liquid; the chemical composition of the initial liquid alloy is 6.14Zn, 2.32Mg, 1.42Cu, 0.54Ti, 0.30Mn, 0.15Cr, 0.11Fe, and 0.25Si in mass fraction; (2) The alloy liquid in step (1) is refined, deslagging, degassing, stirring and deslagging in a holding furnace, and then degassing with argon gas and filtering with a ceramic filter plate online to obtain an alloy refined liquid; (3) casting the alloy refined liquid obtained in step (2) using a semi-continuous casting method to obtain an ingot; (4) The ingot is heated to 440°C, the mold is heated to 450°C, and the extrusion barrel is heated to 430°C; extrusion is started after the temperature reaches the standard; the extrusion outlet speed is controlled to 3m / min; the extrusion outlet temperature is controlled to 480°C; online water quenching is performed at the extrusion outlet, the water temperature is 30°C; and the extrusion is cooled to below 50°C; after extrusion, the extruded part is straightened, and the straightening stretching amount is 0.7%; (5) Saw the straightened plate into the required length, heat the aluminum alloy profile to 470°C, keep it warm for 40 minutes, and then quench it in 30°C water; (6) After solution treatment, the aluminum alloy profile is heated to 185°C, kept at this temperature for 11 hours, and air-cooled to room temperature; then heated to 130°C, kept at this temperature for 11 hours, and air-cooled to room temperature; then heated to 170°C, kept at this temperature for 11 hours, and air-cooled to room temperature; then heated to 110°C, kept at this temperature for 11 hours, and air-cooled to room temperature; (7) After the four-stage artificial aging treatment, holes were drilled and tapped on the aluminum alloy profiles, wires were connected, and the test pieces were polished with sandpapers of 700 to 1100 in sequence; after polishing, they were treated with deionized water, anhydrous ethanol, and acetone in sequence, and then dried with hot air. Then, a H2SO4 solution with a mass fraction of 180 g / L was prepared at a solution temperature of -5 °C, at a voltage of 80 V and a current density of 3 A / dm 2 The aluminum alloy profile was processed for 85 minutes under the conditions to finally produce a lightweight, high-hardness and high-strength aluminum profile. Example 3

[0018] (1) According to the chemical composition and content of 7050 aluminum alloy, the alloy is melted at 760°C, silicon powder and nano-TiC with a particle size of 60 nm are added after melting, and the alloy is stirred evenly to obtain an initial liquid; the chemical composition of the initial liquid alloy is 6.14Zn, 2.32Mg, 1.42Cu, 0.54Ti, 0.30Mn, 0.15Cr, 0.11Fe, and 0.25Si in mass fraction; (2) The alloy liquid in step (1) is refined, deslagging, degassing, stirring and deslagging in a holding furnace, and then degassing with argon gas and filtering with a ceramic filter plate online to obtain an alloy refined liquid; (3) casting the alloy refined liquid obtained in step (2) using a semi-continuous casting method to obtain an ingot; (4) The ingot is heated to 460°C, the mold is heated to 470°C, and the extrusion barrel is heated to 450°C; extrusion is started after the temperature reaches the standard; the extrusion outlet speed is controlled to 3.5m / min; the extrusion outlet temperature is controlled to 490°C; online water quenching is performed at the extrusion outlet, the water temperature is 30°C; and the extrusion is cooled to below 50°C; after extrusion, the extruded part is straightened, and the straightening stretching amount is 0.7%; (5) Saw the straightened plate into the required length, heat the aluminum alloy profile to 475°C, keep it warm for 55 minutes, and then quench it in 30°C water; (6) After solution treatment, the aluminum alloy profile is heated to 190°C, kept at this temperature for 12 hours, and air-cooled to room temperature; then heated to 135°C, kept at this temperature for 12 hours, and air-cooled to room temperature; then heated to 175°C, kept at this temperature for 12 hours, and air-cooled to room temperature; then heated to 115°C, kept at this temperature for 12 hours, and air-cooled to room temperature; (7) After the four-stage artificial aging treatment, holes were drilled and tapped on the aluminum alloy profiles, wires were connected, and the test pieces were polished with sandpapers of 700 to 1100 in sequence; after polishing, they were treated with deionized water, anhydrous ethanol, and acetone in sequence, and then dried with hot air. Then, a H2SO4 solution with a mass fraction of 180 g / L was prepared at a solution temperature of -5 °C, at a voltage of 80 V and a current density of 3 A / dm 2 The aluminum alloy profile was processed for 90 minutes under the conditions to finally produce a lightweight, high-hardness and high-strength aluminum profile.

[0019] Comparative Example 1 The difference between Comparative Example 1 and Example 2 is that in step (1), only 60 nm TiC is added after melting, and the remaining steps are the same as Example 2.

[0020] Comparative Example 2 The difference between Comparative Example 2 and Example 2 is that in step (1), only Si powder is added after melting, and the remaining steps are the same as Example 2.

[0021] Comparative Example 3 The difference between Comparative Example 3 and Example 2 is that step (6) is removed, and the remaining steps are the same as Example 2.

[0022] Comparative Example 4 The difference between Comparative Example 4 and Example 2 is that in step (6), the mixture is only heated to 110° C., kept warm for 11 h, and air-cooled to room temperature. The remaining steps are the same as those in Example 2.

[0023] Comparative Example 5 The difference between Comparative Example 5 and Example 2 is that in step (6), the mixture is heated to 170°C, kept warm for 11 hours, and air-cooled to room temperature; then heated to 110°C, kept warm for 11 hours, and air-cooled to room temperature. The remaining steps are the same as those in Example 2.

[0024] Comparative Example 6 The difference between Comparative Example 6 and Example 2 is that step (7) is removed, and the remaining steps are the same as those of Example 2. Effect example Table 1 below shows the performance analysis results of the aluminum alloy profiles prepared using Examples 1 to 3 of the present invention and Comparative Examples 1 to 6.

[0025] Table 1 Performance test of aluminum alloy profiles of Examples 1-3 and Comparative Examples 1-6

[0026] It can be seen from the results in Table 1 that the present application improves the formula of 7050 aluminum alloy profiles by adding Si and nano-TiC, increases the metastable Al-Si phase in the alloy, assists the formation of alumina crystals, promotes the stability of alumina, improves the corrosion resistance of the aluminum alloy, and provides a low melting point phase for the later selective laser melting of the aluminum alloy, effectively reduces the cracks caused by the laser welding process of the 7050 aluminum alloy, and enables the aluminum profile to play a better application effect in the application of lightweight automobiles. At the same time, adding nano-TiC to the aluminum alloy provides a large number of effective heterogeneous cores for the aluminum alloy, so that the liquid pool is divided more finely and evenly during the crystallization process of aluminum, and the second phase distributed along the grain boundary generated by the eutectic reaction becomes fine and uniform, and finally a highly refined aluminum alloy profile is obtained, which effectively improves the hardness of the aluminum alloy profile. The multi-stage artificial aging treatment provides more energy for the nucleation of the precipitate phase in the aluminum alloy, and retains sufficient time for the growth of the nucleus. The precipitate phase formed is small and uniform, which effectively hinders the dislocation movement of the aluminum alloy, improves the strength of the material, and forms a stable structure, effectively resisting the damage caused by corrosive substances to the material. The recast 7050 aluminum alloy profile is anodized to form a hard and dense oxide film on the surface of the aluminum alloy profile, reducing the surface porosity of the aluminum material, enhancing the hardness of the aluminum material, and extending the service life of the aluminum material.

[0027] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and scope of the equivalent elements of the claims be included in the invention. Any marking in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A processing technology for lightweight, high-hardness and high-strength aluminum profiles, characterized in that: The processing technology comprises the following steps: (1) According to the chemical composition and content of 7050 aluminum alloy, the alloy is melted at 750-800°C, silicon powder and nano-TiC with a particle size of 50-80 nm are added after melting, and the alloy is stirred evenly to obtain an initial liquid; the chemical composition of the initial liquid alloy is 6.14Zn, 2.32Mg, 1.42Cu, 0.54Ti, 0.30Mn, 0.15Cr, 0.11Fe, and 0.25Si in mass fraction; (2) The alloy liquid in step (1) is refined, deslagging, degassing, stirring and deslagging in a holding furnace, and then degassing with argon gas and filtering with a ceramic filter plate online to obtain an alloy refined liquid; (3) casting the alloy refined liquid obtained in step (2) using a semi-continuous casting method to obtain an ingot; (4) Heat the ingot to 420-460℃, the mold to 430-470℃, and the extrusion barrel to 420-450℃; start extrusion after the temperature reaches the standard; control the extrusion outlet speed to 2.5-3.5m / min; control the extrusion outlet temperature to 470-490℃; perform online water quenching at the extrusion outlet, the water temperature is 20-40℃; cool to below 50℃; after extrusion, straighten the extruded part, and the straightening stretching amount is 0.5-0.8%; (5) sawing the straightened plate into the required length and performing solid solution treatment on the aluminum alloy profile; (6) After solution treatment, four-level artificial aging treatment is carried out; (7) After the four-level artificial aging treatment, the aluminum alloy profile is hard anodized to obtain a lightweight, high-hardness and high-strength aluminum profile.

2. The processing technology of a lightweight, high-hardness and high-strength aluminum profile according to claim 2 is characterized in that: The solution treatment in step (5) is to heat the aluminum alloy profile to 465-470°C, keep the temperature for 35-55 minutes, and then quench in 20-40°C water.

3. The processing technology of a lightweight, high-hardness and high-strength aluminum profile according to claim 2 is characterized in that: The four-stage artificial aging treatment in step (6) includes a first stage of high-temperature aging treatment, a second stage of low-temperature aging treatment, a third stage of high-temperature aging treatment, and a fourth stage of low-temperature aging treatment.

4. The processing technology of a lightweight, high-hardness and high-strength aluminum profile according to claim 4 is characterized in that: The first stage of high temperature aging treatment is to heat the aluminum alloy profile to 180-190°C, keep it warm for 10-12 hours, and air cool it to room temperature; the second stage of low temperature aging treatment is to heat it to 125-135°C, keep it warm for 10-12 hours, and air cool it to room temperature; the third stage of high temperature aging treatment is to heat it to 165-175°C, keep it warm for 10-12 hours, and air cool it to room temperature; the fourth stage of low temperature aging treatment is to heat it to 105-115°C, keep it warm for 10-12 hours, and air cool it to room temperature.

5. The processing technology of a lightweight, high-hardness and high-strength aluminum profile according to claim 2 is characterized in that: The hard anodizing treatment in step (7) is to pre-treat the aluminum alloy profile, prepare an electrolyte, and then conduct the hard anodizing treatment at a voltage of 50-120 V and a current density of 0.6-4.5 A / dm 2 Under the conditions of , process for 80~90min.

6. The processing technology of a lightweight, high-hardness and high-strength aluminum profile according to claim 6 is characterized in that: The aluminum alloy profile pretreatment is to drill holes and tap threads on the aluminum alloy profile, connect wires, and polish the test piece with sandpaper of No. 700-1100 in sequence; after polishing, it is treated with deionized water, anhydrous ethanol, and acetone in sequence, and finally dried with hot air.

7. The processing technology of a lightweight, high-hardness and high-strength aluminum profile according to claim 6 is characterized in that: The electrolyte is a H2SO4 solution with a mass fraction of 170-180 g / L and a solution temperature of -3-5°C.

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