Preparation method capable of improving surface quality of 6-series aluminum alloy regenerated aluminum profile

Abstract

The invention discloses a preparation method capable of improving the surface quality of a 6-series aluminum alloy regenerated aluminum profile. The 6XXX-series aluminum alloy capable of improving the surface quality comprises the following components: 0.4-0.8% of silicon, less than or equal to 0.5% of iron, 0.15-0.4% of copper, less than or equal to 0.15% of manganese, 0.8-1.2% of magnesium, 0.04-0.35% of chromium, less than or equal to 0.25% of zinc, less than or equal to 0.15% of titanium and the balance of aluminum and other inevitable impurity elements. The preparation method of the 6XXX series aluminum alloy capable of improving the surface quality comprises the steps of smelting and casting, homogenization treatment, extrusion process optimization and a heat treatment technology, a 6XXX series aluminum alloy product prepared through the preparation method has the good surface quality, and the alloy performance can be as follows: the tensile strength is larger than or equal to 260 MPa, the yield strength is larger than or equal to 240 MPa, and the ductility is larger than or equal to 9%; the secondary aluminum formed by recovering and smelting the waste aluminum is more and more widely applied to the production of the aluminum extruded profile, but the surface quality of the extruded profile is generally lower than that of the primary aluminum due to the complex components and higher impurity content of the secondary aluminum, so that the success of the technology has obvious advantages and better market prospect.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of aluminum alloy materials, and particularly relates to a preparation method for improving the surface quality of 6-series aluminum alloy recycled aluminum profiles. BACKGROUND

[0002] With the increasing demand for sustainable development of the aluminum industry, the recycling of recycled aluminum has become an important way to reduce energy consumption and carbon emissions. 6-series aluminum alloys (such as 6061, 6063, 6082, etc.) are aluminum-magnesium-silicon (Al-Mg-Si) heat-treatable strengthening alloys. Due to their excellent comprehensive performance, good processability and high cost performance, they have become the preferred materials in the fields of construction, transportation, electronics and machinery manufacturing.

[0003] In the production of aluminum alloy extruded profiles, 6-series aluminum alloys (such as 6061, 6063, 6082, etc.) are widely used in the fields of construction, automobiles, electronics, etc. due to their good extrudability, medium strength and corrosion resistance. However, recycled aluminum contains a large amount of impurity elements (such as Fe, Si, etc.) and non-metallic inclusions, which can easily lead to surface defects (such as cracks, segregation, oxidation inclusions, etc.) during casting and extrusion, thereby affecting the appearance, surface quality and mechanical properties of the extruded profiles.

[0004] The preparation process of traditional 6xxx-series aluminum alloys usually uses high-purity primary aluminum as the main raw material, which can ensure the quality of the profiles but has high cost and does not meet the green manufacturing trend. When directly using recycled aluminum, due to large composition fluctuations and high impurity content, surface roughness, stripes, color difference and other problems are easily generated during extrusion, which is difficult to meet the requirements of high-end profiles. Especially in the key links of homogenization treatment, extrusion temperature control and cooling process, the existing technology is not suitable for recycled aluminum, resulting in low yield of profile products and unstable performance.

[0005] At present, in order to improve the surface quality of recycled aluminum alloy profiles, some other metal elements are usually added during melting. However, direct addition without blending usually leads to a decrease in the mechanical properties of the aluminum alloy and poor profile quality, and the surface quality cannot be satisfactorily improved. Therefore, a preparation method for improving the surface quality of 6-series aluminum alloy recycled aluminum profiles is needed, which can significantly improve the surface quality and mechanical properties of the cast bar and extruded profile while ensuring cost advantage, so as to meet the requirements of high-end applications. SUMMARY

[0006] (1) Technical problems to be solved

[0007] The present application aims at the above problems in the prior art, in order to make up for the deficiencies of the prior art, the present application provides a preparation method for improving the surface quality of 6 series aluminum alloy recycled aluminum profile, in order to improve the surface quality of recycled aluminum alloy profile in the prior art, other metal elements are added in the smelting process without blending, which finally leads to the decline of the performance of the produced aluminum alloy profile, the quality deterioration, the low finished product rate of the aluminum alloy profile and the unstable performance, according to the defects existing in the prior art, the original formula is improved, the basic elements are optimized, and the heat treatment process is matched, so as to optimize the alloy component ratio, effectively control the casting and homogenization parameters, solve the industry problems of many surface defects of recycled aluminum ingot and unstable quality of extruded profile by combining extrusion temperature-speed matching and high-efficiency cooling technology, and improve the surface quality and mechanical properties of the profile made of recycled aluminum.

[0008] (2) Technical scheme

[0009] In order to achieve the above technical purpose, the present application provides two schemes as follows:

[0010] The first scheme of the present application is a preparation method for improving the surface quality of 6 series aluminum alloy recycled aluminum profile, which comprises the following components: silicon 0.4-0.8%, iron ≤0.5%, copper 0.15-0.4%, manganese ≤0.15%, magnesium 0.8-1.2%, chromium 0.04-0.35%, zinc ≤0.25%, titanium ≤0.15%, and the balance is aluminum and other unavoidable impurity elements.

[0011] The second scheme of the present application is a preparation method for improving the surface quality of 6 series aluminum alloy recycled aluminum profile, which comprises the following steps:

[0012] Smelting and casting: ①Smelting intermediate alloy: according to the mass percentage of silicon 0.4-0.8%, iron ≤0.5%, copper 0.15-0.4%, manganese ≤0.15%, magnesium 0.8-1.2%, chromium 0.04-0.35%, zinc ≤0.25%, titanium ≤0.15% and the balance of aluminum, the raw materials are prepared to obtain smelting metal, wherein pure zinc ingot is used for zinc, 40-60% first-class waste aluminum and 40-60% high-purity low-iron aluminum ingot are used for aluminum, pure magnesium ingot is used for magnesium, aluminum-silicon intermediate alloy, aluminum-iron intermediate alloy, aluminum-copper intermediate alloy, aluminum-manganese intermediate alloy, aluminum-chromium intermediate alloy and aluminum-titanium-boron intermediate alloy are used for silicon, iron, copper, manganese, chromium and titanium; pure aluminum ingot is loaded into the furnace, the furnace gas temperature is set to 750-780℃, and slagging is carried out after the pure aluminum ingot is melted;

[0013] Then add other intermediate alloy except aluminum titanium boron intermediate alloy and pure magnesium ingot and wait for its complete melting, after the charge is melted, the temperature is 745-755℃, after slagging, add pure magnesium ingot and carry out stirring;

[0014] ②Warm up to 745-755℃, use high-purity argon and sodium-free refining agent to refine, use time 10-15min, then carry out slagging, standing;

[0015] ③After the casting temperature reaches 745-755℃, start casting, in the casting process, carry out aluminum titanium boron intermediate alloy wire feeding, get casting ingot A;

[0016] Among them, according to different casting specifications, the casting speed is set differently, when the casting rod specification is φ292, the casting speed is 50-55mm / min; when the casting rod specification is φ234, the casting speed is 70-75mm / min; when the casting rod specification is φ178, the casting speed is 85-90mm / min;

[0017] 2)Homogenization treatment: the casting ingot A in step 1) is subjected to homogenization treatment by using homogenization process, set the first stage temperature to 585℃, use time 8h; after the second stage homogenization is discharged, get the homogenized casting ingot B after strong air cooling;

[0018] 3)Extrusion process optimization: heat the homogenized casting ingot B in step 2) and extrude, extrusion temperature: casting ingot temperature 470℃ matches with die temperature, preheat the die to 470℃ to avoid temperature difference leading to surface cracks or deformation. Extrusion cylinder temperature control 460℃, prevent sticking aluminum. Extrusion speed: too fast is easy to cause surface thermal cracks (such as "bamboo joints"), too slow may cause uneven cooling. Adjust the speed to 10m / min, complex section needs low speed extrusion;

[0019] Set the discharge port temperature >540℃, cooling uniformity: use air cooling or water mist cooling to avoid the profile bending or color difference due to uneven cooling, strictly control the cooling rate for quenching process (T5 / T6 treatment) to obtain extruded profile;

[0020] 4)Heat treatment technology: heat the profile after extrusion in step 3) to 185℃, time 10 hours, improve hardness and strength.

[0021] Through extrusion and aging process, the alloy performance of the 6xxx series aluminum alloy product prepared by the above method can reach: tensile strength ≥260MPa, yield strength ≥240MPa, elongation ≥9%;

[0022] Further optimization, the strength can be increased by about 10-20MPa.

[0023] Further, the primary waste aluminum mainly comes from clean industrial waste in the production or processing of aluminum alloy, for example: cutting head, tail, and corner material of extruded profiles (without coating and oil stain); aluminum chips generated by machining (after degreasing and drying treatment); waste billets in the process of stamping and forging (without being contaminated by other metal or non-metal impurities), which are usually single brand or same series alloy without mixing other alloys, with extremely low impurity content, and controllable content of impurity elements such as iron and silicon.

[0024] Further, the air volume required by the strong air cooling is greater than 2500m 3 / h, the air volume is 72000m 3 / h, 85% air volume is maintained below 550℃, the air speed is generally between 2.5m / s and 3.2m / s, and the cooling termination temperature is 150℃.

[0025] (3) Beneficial effects

[0026] Unlike the prior art, the base elements of the present application are selected from common elements, which are low in cost.

[0027] 1. Optimizing alloy composition and improving utilization rate of recycled aluminum: by precisely controlling the content range of elements such as Si, Mg, Cu, and Cr, and adopting a ratio of 40-60% primary waste aluminum + 40-60% high-purity aluminum ingot, the utilization rate of recycled aluminum is significantly improved while the material performance is ensured, the production cost is reduced, and the green and low-carbon manufacturing trend is met; the content of Fe is limited and the ratio of Fe / Si is adjusted to reduce the formation of coarse iron-rich phases and reduce the risk of surface cracks and segregation; the addition of Cr element refines the grains to improve the mechanical properties and surface finish of the extruded profiles; by adding Cu / Cr / Ti, a good balance effect is achieved, which can further improve the surface quality in the 6-series alloy system, and the stability of aluminum alloy strength and surface quality is controlled by controlling the ratio of waste aluminum, the present application strictly controls the ratio of Mg and Si to further ensure the balance of strength and surface quality.

[0028] 2. Improving melting and casting process to reduce inclusions and defects: high-purity argon and sodium-free refining agents are used for refining to effectively remove gas and inclusions in the melt, reduce internal pores and oxidized inclusions in the ingot, optimize the wire feeding process of aluminum-titanium-boron intermediate alloy, refine the as-cast structure, and improve the uniformity and extrudability of the ingot, dynamically adjust the casting speed and cooling water flow according to the size of the cast bar to ensure uniform solidification of the ingot and reduce surface cold shut and cracks.

[0029] 3. Optimized homogenization treatment to improve organizational uniformity: a two-stage homogenization process is adopted to effectively eliminate dendritic segregation and improve subsequent extrusion performance.

[0030] 4. Precise control of extrusion process, improve surface quality: reduce the risk of sticking aluminum and surface scratches by preheating the mold, matching the ingot temperature and controlling the temperature of the extrusion cylinder; set the extrusion speed reasonably to avoid fast heat cracks or slow cooling unevenness to ensure smooth profile surface; use discharge temperature >540℃+ strong wind / water mist cooling to optimize quenching effect (T5 / T6) and reduce deformation and color difference.

[0031] 5. Stable heat treatment process to ensure mechanical properties: use low-temperature aging process of 185℃x10h to balance the strength and elongation of the profile, so that the final product meets the high performance requirements of tensile strength ≥260MPa, yield strength ≥240MPa, elongation ≥9%, and the final extruded profile surface is free of scratches, peeling, bubbles, cracks, indentations, color difference, and meets the needs of high-end applications.

[0032] In summary, the present application significantly improves the surface quality and mechanical properties of 6 series aluminum alloy extruded profiles while ensuring low cost and high recycled aluminum utilization. BRIEF DESCRIPTION OF DRAWINGS

[0033] The present application will be further described below in conjunction with the drawings and examples. Among them:

[0034] Figure 1 A preparation method for improving the surface quality of 6 series aluminum alloy recycled aluminum profile. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all.

[0036] Example 1:

[0037] A preparation method for improving the surface quality of 6 series aluminum alloy recycled aluminum profile, comprising the following steps:

[0038] 1) Melting and casting: ① Melting intermediate alloy: raw materials are prepared according to the following mass percentage: silicon 0.6%, iron 0.1%, copper 0.35%, manganese 0.12%, magnesium 1.0%, chromium 0.12%, zinc 0.11%, titanium 0.01%, and the balance being aluminum. Pure zinc ingot, 50% first-grade waste aluminum, and 50% high-purity low-iron aluminum ingot, and pure magnesium ingot are used for zinc, aluminum, and magnesium. Aluminum silicon intermediate alloy, aluminum iron intermediate alloy, aluminum copper intermediate alloy, aluminum manganese intermediate alloy, aluminum chromium intermediate alloy, and aluminum titanium boron intermediate alloy are used for silicon, iron, copper, manganese, chromium, and titanium. Pure aluminum ingot is loaded into the furnace, and the furnace gas temperature is set to 750-780°C. After the pure aluminum ingot is melted, slag is removed, and then other intermediate alloys except for the aluminum titanium boron intermediate alloy and pure magnesium ingot are added and completely melted. After the furnace charge is melted, the temperature is 745-755°C, and after slagging, the pure magnesium ingot is added and stirred.

[0039] ② The temperature is raised to 745-755°C, high-purity argon gas and sodium-free refining agent are used for refining, and the time is 10-15 min. Then, slagging and standing are performed.

[0040] ③ After the casting temperature reaches 745-755°C, casting is started. In the casting process, aluminum titanium boron intermediate alloy wire feeding is performed, and ingot A is obtained.

[0041] The wire feeding speed of the aluminum titanium boron intermediate alloy is 0.8 m / min, the water flow is 1000 L / min, the water temperature is 30°C, and the casting speed is set differently according to different casting specifications. When the casting rod specification is φ292, the casting speed is 50-55 mm / min; when the casting rod specification is φ234, the casting speed is 70-75 mm / min; and when the casting rod specification is φ178, the casting speed is 85-90 mm / min.

[0042] 2) Homogenization treatment: the ingot A in step 1) is subjected to homogenization treatment using a homogenization process, and the first stage temperature is set to 585°C for 10 h. After the second stage homogenization is discharged, forced air cooling is performed, and the homogenized ingot B is obtained.

[0043] 3) Extrusion process optimization: the homogenized ingot B in step 2) is heated and extruded, and the extrusion temperature is 460-480°C matching the mold temperature (the mold is preheated to 460-480°C) to avoid surface cracks or deformation caused by temperature difference. The extrusion cylinder temperature is controlled at 450-470°C to prevent aluminum sticking. The extrusion speed is adjusted to 5-15 m / min, and complex sections require low-speed extrusion. The discharge port temperature is set to >540°C, and the cooling uniformity is achieved by air cooling or water mist cooling to avoid bending or color difference caused by uneven cooling. The quenching process (T5 / T6 treatment) needs to strictly control the cooling rate to obtain the extruded profile.

[0044] 4) Heat treatment technology: heat treatment of the profile after extrusion in step 3): ① heating to 185°C, holding for 10 hours, improving hardness and strength.

[0045] After the above heat treatment, the product is detected for performance, hardness, size, etc., and the final product is obtained after the product is qualified.

[0046] Example 2:

[0047] A preparation method for improving the surface quality of 6 series aluminum alloy recycled aluminum profile, comprising the following steps:

[0048] 1) Melting and casting: ① Melting intermediate alloy: preparing materials according to mass percentage of silicon 0.4%, iron 0.1%, copper 0.25%, manganese 0.1%, magnesium 1.2%, chromium 0.12%, zinc 0.10%, titanium 0.01%, and the balance of aluminum, obtaining a molten metal, wherein zinc, aluminum and magnesium are pure zinc ingot, 40% first-class waste aluminum and 60% high-purity low-iron aluminum ingot and pure magnesium ingot, silicon, iron, copper, manganese, chromium and titanium are aluminum-silicon intermediate alloy, aluminum-iron intermediate alloy, aluminum-copper intermediate alloy, aluminum-manganese intermediate alloy, aluminum-chromium intermediate alloy and aluminum-titanium-boron intermediate alloy; pure aluminum ingot is loaded into the furnace, the furnace gas temperature is set to 750-780°C, after the pure aluminum ingot is melted, slag is removed, then other intermediate alloys except aluminum-titanium-boron intermediate alloy and pure magnesium ingot are added and completely melted, after the furnace charge is melted, the temperature is 745-755°C, after slagging, pure magnesium ingot is added and stirred;

[0049] ② Heating to 745-755°C, using high-purity argon and sodium-free refining agent for refining, taking 10-15 min, then slagging and standing;

[0050] ③ After the casting temperature reaches 745-755°C, casting is started, during the casting process, aluminum-titanium-boron intermediate alloy wire feeding is performed, obtaining ingot A;

[0051] Among them, the wire feeding speed of aluminum-titanium-boron intermediate alloy is 0.8 m / min, the water flow is 1000 L / min, the water temperature is 30°C, and according to different casting specifications, the casting speed is set differently, when the casting rod specification is φ292, the casting speed is 50-55 mm / min; the specification is φ234, the casting speed is 70-75 mm / min; the specification is φ178, the casting speed is 85-90 mm / min.

[0052] 2) Homogenization treatment: the ingot A in step 1) is subjected to homogenization treatment by homogenization process, the first stage temperature is set to 585°C, and the time is 8h; after the second stage homogenization is discharged, it is cooled by strong wind, obtaining homogenized ingot B;

[0053] 3) Extrusion process optimization: heat extrusion of the homogenized ingot B in step 2), extrusion temperature: ingot temperature 460-480℃ matched with die temperature (die preheated to 460-480℃), avoid temperature difference leading to surface cracks or deformation. Extrusion cylinder temperature control 450-470℃, prevent sticking aluminum. Extrusion speed: too fast can easily lead to surface thermal cracks (such as "bamboo joints"), too slow can cause uneven cooling. Speed adjustment 5-15m / min, complex section needs low speed extrusion. Set discharge temperature >540℃, cooling uniformity: use air cooling or water mist cooling, avoid profile bending or color difference due to uneven cooling. Quenching process (T5 / T6 treatment) needs to strictly control the cooling rate to obtain the extruded profile.

[0054] 4) Heat treatment technology: heat treatment of the profile after extrusion in step 3): ① heat to 185°C, hold for 10 hours, increase hardness and strength.

[0055] Perform performance, hardness, size, etc. on the product after heat treatment, and obtain the final product after the product is qualified.

[0056] Example 3:

[0057] A preparation method for improving the surface quality of 6 series aluminum alloy recycled aluminum profile, comprising the following steps:

[0058] 1) Melting and casting: ① Melting intermediate alloy: prepare materials according to mass percentage of silicon 0.8%, iron 0.1%, copper 0.35%, manganese 0.12%, magnesium 0.8%, chromium 0.12%, zinc 0.11%, titanium 0.01%, and the balance of aluminum, wherein zinc, aluminum, and magnesium are pure zinc ingot, 60% first-class waste aluminum, and 40% high-purity low-iron aluminum ingot and pure magnesium ingot, silicon, iron, copper, manganese, chromium, and titanium are aluminum-silicon intermediate alloy, aluminum-iron intermediate alloy, aluminum-copper intermediate alloy, aluminum-manganese intermediate alloy, aluminum-chromium intermediate alloy, and aluminum-titanium-boron intermediate alloy; load pure aluminum ingot into the furnace, set the furnace gas temperature to 750-780℃, and after the pure aluminum ingot is melted, perform slag removal, then add other intermediate alloys except aluminum-titanium-boron intermediate alloy and pure magnesium ingot and wait for them to completely melt, after the furnace charge is melted, the temperature is 745-755℃, after slag removal, add pure magnesium ingot and stir;

[0059] ② Raise the temperature to 745-755℃, use high-purity argon and sodium-free refining agent for refining, for 10-15min, then perform slag removal and standing;

[0060] ③ After the casting temperature reaches 745-755℃, start casting, and during the casting process, perform aluminum-titanium-boron intermediate alloy wire feeding, to obtain ingot A;

[0061] The wire feeding speed of the aluminum-titanium-boron intermediate alloy is 0.8 m / min, the water flow is 1000 L / min, the water temperature is 30℃, and the casting speed is set differently according to different casting specifications, when the casting rod specification is φ292, the casting speed is 50-55 mm / min; when the casting rod specification is φ234, the casting speed is 70-75 mm / min; when the casting rod specification is φ178, the casting speed is 85-90 mm / min.

[0062] 2) homogenization treatment: the ingot A in step 1) is subjected to homogenization treatment by using a homogenization process, the first stage temperature is set to 585℃, and the time is 10h; after the second stage homogenization is discharged, forced air cooling is performed to obtain the homogenized ingot B;

[0063] 3) extrusion process optimization: the homogenized ingot B in step 2) is heated and extruded, the extrusion temperature is 460-480℃ of the ingot temperature matched with the die temperature (the die is preheated to 460-480℃), so as to avoid surface cracks or deformation caused by temperature difference. The extrusion cylinder temperature is controlled to be 450-470℃ to prevent aluminum sticking. The extrusion speed: too fast speed is easy to cause surface thermal cracks (such as "bamboo joints"), and too slow speed may cause uneven cooling. The speed is adjusted to be 5-15 m / min, and low speed extrusion is required for complex cross section. The discharge port temperature is set to be >540℃, and the cooling uniformity is: air cooling or water mist cooling is adopted to avoid bending or color difference of the profile caused by uneven cooling. The quenching process (T5 / T6 treatment) needs to strictly control the cooling rate to obtain the extruded profile.

[0064] 4) heat treatment technology: the profile after extrusion in step 3) is subjected to heat treatment: ① heated to 185°C, and kept for 10 hours to improve hardness and strength.

[0065] The product after the above heat treatment is subjected to performance, hardness, size and other tests, and the final product is obtained after the product is qualified.

[0066] Example 4:

[0067] A preparation method for improving the surface quality of 6-series aluminum alloy recycled aluminum profile, comprising the following steps:

[0068] 1) Melting and casting: ① Melting intermediate alloy: raw materials are prepared according to the following mass percentage: silicon 0.8%, iron 0.1%, copper 0.15%, manganese 0.15%, magnesium 0.8%, chromium 0.35%, zinc 0.25%, titanium 0.15%, and the balance being aluminum, wherein pure zinc ingot, 60% first-grade waste aluminum, and 40% high-purity low-iron aluminum ingot, and pure magnesium ingot are used for zinc, aluminum, and magnesium; aluminum silicon intermediate alloy, aluminum iron intermediate alloy, aluminum copper intermediate alloy, aluminum manganese intermediate alloy, aluminum chromium intermediate alloy, and aluminum titanium boron intermediate alloy are used for silicon, iron, copper, manganese, chromium, and titanium; pure aluminum ingot is loaded into the furnace, the furnace gas temperature is set to 750-780°C, the slag is removed after the pure aluminum ingot is melted, then the other intermediate alloys except the aluminum titanium boron intermediate alloy and the pure magnesium ingot are added and completely melted, after the furnace charge is melted, the temperature is 745-755°C, the pure magnesium ingot is added after slagging and stirring is performed;

[0069] ② The temperature is raised to 745-755°C, high-purity argon gas and sodium-free refining agent are used for refining, and the time is 10-15 min, then slagging and standing are performed;

[0070] ③ After the casting temperature reaches 745-755°C, casting is started, and aluminum titanium boron intermediate alloy wire feeding is performed during the casting process to obtain cast ingot A;

[0071] The wire feeding speed of the aluminum titanium boron intermediate alloy is 0.8 m / min, the water flow is 1000 L / min, the water temperature is 30°C, and the casting speed is set differently according to different casting specifications, when the casting rod specification is φ292, the casting speed is 50-55 mm / min; when the casting rod specification is φ234, the casting speed is 70-75 mm / min; when the casting rod specification is φ178, the casting speed is 85-90 mm / min.

[0072] 2) Homogenization treatment: the cast ingot A in step 1) is subjected to homogenization treatment using a homogenization process, the first stage temperature is set to 575°C, and the time is 10 h; after the second stage homogenization is discharged, forced air cooling is performed to obtain the homogenized cast ingot B;

[0073] 3) Extrusion process optimization: the homogenized cast ingot B in step 2) is heated and extruded, the extrusion temperature is 460-480°C matching the mold temperature (the mold is preheated to 460-480°C) to avoid surface cracks or deformation caused by temperature difference. The extrusion cylinder temperature is controlled to 450-470°C to prevent aluminum sticking. The extrusion speed is adjusted to 5-15 m / min, complex sections require low-speed extrusion. The discharge port temperature is set to >540°C, and the cooling uniformity is achieved by air cooling or water mist cooling to avoid bending or color difference caused by uneven cooling. The quenching process (T5 / T6 treatment) needs to strictly control the cooling rate to obtain the extruded profile.

[0074] 4) Heat treatment technology: heat treatment of the profile after step 3) extrusion: ① heating to 200°C, holding for 4 hours, improving hardness and strength.

[0075] The product after the above heat treatment is subjected to performance, hardness, size and other tests, and the final product is obtained after the product is qualified.

[0076] Example 5:

[0077] A preparation method for improving the surface quality of 6 series aluminum alloy recycled aluminum profile, comprising the following steps:

[0078] 1) Melting and casting: ① Melting intermediate alloy: preparing materials according to mass percentage of silicon 0.8%, iron 0.5%, copper 0.4%, manganese 0.15%, magnesium 0.8%, chromium 0.04%, zinc 0.11%, titanium 0.01%, and the balance of aluminum, wherein pure zinc ingot, 60% first-class waste aluminum and 40% high-purity low-iron aluminum ingot and pure magnesium ingot are used for zinc, aluminum and magnesium, and aluminum-silicon intermediate alloy, aluminum-iron intermediate alloy, aluminum-copper intermediate alloy, aluminum-manganese intermediate alloy, aluminum-chromium intermediate alloy and aluminum-titanium-boron intermediate alloy are used for silicon, iron, copper, manganese, chromium and titanium; pure aluminum ingot is loaded into the furnace, the furnace gas temperature is set to 750-780°C, after the pure aluminum ingot is melted, the slag is removed, then the other intermediate alloys except aluminum-titanium-boron intermediate alloy and pure magnesium ingot are added and completely melted, after the furnace charge is melted, the temperature is 745-755°C, after slagging, pure magnesium ingot is added and stirred;

[0079] ② Heating to 745-755°C, using high-purity argon and sodium-free refining agent for refining, for 10-15 min, then slagging and standing;

[0080] ③ After the casting temperature reaches 745-755°C, casting is started, and aluminum-titanium-boron intermediate alloy wire feeding is performed during casting to obtain ingot A;

[0081] The wire feeding speed of the aluminum-titanium-boron intermediate alloy is 0.8 m / min, the water flow is 1000 L / min, the water temperature is 30°C, and the casting speed is set differently according to different casting specifications, when the casting rod specification is φ292, the casting speed is 50-55 mm / min; when the casting rod specification is φ234, the casting speed is 70-75 mm / min; when the casting rod specification is φ178, the casting speed is 85-90 mm / min.

[0082] 2) Homogenization treatment: the ingot A in step 1) is subjected to homogenization treatment using homogenization process, the first stage temperature is set to 580°C, and the time is 8h; after the second stage homogenization is discharged, it is cooled by strong wind to obtain homogenized ingot B;

[0083] 3) Extrusion process optimization: the homogenized ingot B in step 2) is heated and extruded, the extrusion temperature: ingot temperature 460-480°C matched with die temperature (die preheated to 460-480°C), to avoid temperature difference leading to surface cracks or deformation. Extrusion cylinder temperature control 450-470°C, to prevent sticking aluminum. Extrusion speed: too fast can easily lead to surface thermal cracks (such as "bamboo joints"), too slow can cause uneven cooling. The speed is adjusted to 5-15 m / min, and low speed extrusion is required for complex cross-section. The set discharge temperature is >540°C, and the cooling uniformity: air cooling or water mist cooling is used to avoid bending or color difference due to uneven cooling. The quenching process (T5 / T6 treatment) needs to strictly control the cooling rate to obtain the extruded profile.

[0084] 4) Heat treatment technology: the profile after extrusion in step 3) is heat treated: ① heated to 150°C, held for 12 hours, to improve hardness and strength.

[0085] The product after heat treatment is subjected to performance, hardness, size and other tests, and the final product is obtained after the product is qualified.

[0086] Comparative Example 1: different from Example 1 is that no primary waste aluminum is added in step 1), and the rest is the same as Example 1.

[0087] Comparative Example 2: different from Example 1 is that the extrusion speed is set to 1.0 mm / s in step 3), and the outlet temperature is 530-540°C, and the rest is the same as Example 1.

[0088] Comparative Example 3: different from Example 1 is that the solution treatment temperature is set to 585°C for 6h in step 4), and the aging treatment temperature is set to 175°C for 8h, and the rest is the same as Example 1.

[0089] According to the above examples, the following data is obtained, and a table is drawn

[0090]

[0091] From the above test data, it can be concluded that from Examples 1-3 and Comparative Example 1, the performance of the product is higher when the ratio of primary waste aluminum to pure aluminum is used compared to the product made only from pure aluminum ingot, and the surface quality also reaches a high level, and the production cost of recycled aluminum is 30%-50% lower than that of primary aluminum, greatly saving the cost; from Examples 1-3 and Comparative Example 2, it can be seen that controlling the extrusion speed and outlet temperature during hot extrusion has a significant effect on the mechanical properties of the profile; from Examples 1-3 and Comparative Example 3, it can be seen that the temperature range and holding time of solution treatment + aging treatment can greatly affect the mechanical properties of the product.

[0092] The above embodiments are the preferred embodiments of the present application, although the present application is described in detail with reference to the foregoing embodiments, the embodiments of the present application are not limited to the above embodiments, and those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or equivalently replace part of the technical features, any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for improving the surface quality of recycled 6000 series aluminum alloy aluminum profiles, characterized by: The 6-series aluminum alloy recycled aluminum profile can improve the following components: Silicon 0.4-0.8%, iron ≤0.5%, copper 0.15-0.4%, manganese ≤0.15%, magnesium 0.8-1.2%, chromium 0.04-0.35%, zinc ≤0.25%, titanium ≤0.15%, the balance is aluminum and other inevitable impurity elements; the total mass of other inevitable impurity elements is not more than 0.15% of the total mass of the alloy.

2. The preparation method of claim 1, wherein the method is characterized by: It includes the following processes: 1) Melting and casting: ① Melting intermediate alloy: according to mass percentage, silicon 0.4-0.8%, iron ≤0.5%, copper 0.15-0.4%, manganese ≤0.15%, magnesium 0.8-1.2%, chromium 0.04-0.35%, zinc ≤0.25%, titanium ≤0.15%, and the balance is aluminum, the raw materials are prepared, and the melting metal is obtained, wherein pure zinc ingot is used for zinc, 40-60% first-class waste aluminum and 40-60% high-purity low-iron aluminum ingot are used for aluminum, pure magnesium ingot is used for magnesium, silicon, iron, copper, manganese, chromium and titanium are respectively used for aluminum-silicon intermediate alloy, aluminum-iron intermediate alloy, aluminum-copper intermediate alloy, aluminum-manganese intermediate alloy, aluminum-chromium intermediate alloy and aluminum-titanium-boron intermediate alloy; 40-60% first-class waste aluminum and 40-60% high-purity low-iron aluminum ingot are loaded into the furnace, the furnace gas temperature is set to 750-780℃, and after the pure aluminum ingot is melted, the slag is removed; Then add other intermediate alloys except aluminum-titanium-boron intermediate alloy and pure magnesium ingot and wait for it to completely melt, after the furnace charge is melted, the temperature is 745-755℃, after slagging, pure magnesium ingot is added and stirred; ② Raise the temperature to 745-755℃, use high-purity argon and sodium-free refining agent for refining, use for 10-15min, then remove the slag and stand still; ③ After the casting temperature reaches 745-755℃, start casting, during the casting process, aluminum-titanium-boron intermediate alloy wire feeding is carried out, and ingot A is obtained; 2) Homogenization treatment: the ingot A in step 1) is treated by homogenization process, the first stage temperature is set to 575-585℃, and the use time is 8-10h; after the second stage homogenization is discharged, strong air cooling is carried out, and the homogenized ingot B is obtained; 3) Extrusion process optimization: the homogenized ingot B in step 2) is heated and extruded; First, preheat the mold to 460-480℃ to facilitate temperature matching, and set the ingot temperature to 460-480℃ to avoid surface cracks or deformation caused by temperature difference; Control the extrusion cylinder temperature between 450-470℃ to prevent aluminum sticking, control the extrusion speed, too fast extrusion speed can easily cause surface hot cracks, too slow can cause uneven cooling, so set the speed to 5-15m / min, if complex cross-section part is encountered, low speed extrusion is needed; Set the discharge port temperature >540℃, cooling uniformity: use air cooling or water mist cooling to avoid bending or color difference of the profile due to uneven cooling; Quenching process adopts T5 or T6 mode treatment, and the cooling rate needs to be strictly controlled, so as to obtain the extruded profile; 4) Heat treatment technology: heat the profile after step 3) to 150-200℃, and keep it for 4-12 hours to improve hardness and strength; The product after the heat treatment is detected for performance, hardness, size and other items, and the final product is obtained after the product is qualified.

3. The preparation method of claim 2, wherein the method is characterized in that: Among them, The wire feeding speed of the aluminum-titanium-boron intermediate alloy in step 1) is 1.2-1.5 m / min, and the water flow is set to 1000-1200 L / min during casting, and the water temperature is controlled between 20-30℃.

4. The preparation method of claim 3, wherein the method is characterized in that: Among them, In step 1), the casting speed is set differently according to different casting specifications. When the casting rod specification is φ292, the casting speed is 50-55 mm / min; when the casting rod specification is φ234, the casting speed is 70-75 mm / min; and when the casting rod specification is φ178, the casting speed is 85-90 mm / min.

5. The preparation method of claim 3 or 4, wherein the method is characterized in that: Among them, The cooling method in step 3) is strong wind cooling, and the intensity is set to 100.

6. The preparation method of claim 5, wherein the method is characterized in that: Among them, The heating temperature of the heat treatment technology in step 4) is: heated to 185℃, and kept for 10 hours.

7. The method according to claim 6, wherein the method for improving the surface quality of recycled 6000 series aluminum alloy profiles is characterized in that the method further comprises the step of: After the heat treatment technology in step 4), the profile surface is free of scratches, peeling, bubbles, cracks, indentations, and color differences. ​ 8. The preparation method of claim 7, wherein the surface quality of the recycled 6000 series aluminum alloy profile is improved. After the heat treatment technology in step 4), the tensile strength of the profile is ≥260 MPa, the yield strength is ≥240 MPa, and the elongation is ≥9%.

9. The preparation method of claim 8, wherein the method is characterized by: Among them, The proportion of primary waste aluminum in step 1) is 50%.

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