Easily-processed and corrosion-resistant aluminum alloy pipe and preparation process thereof

Abstract

The invention discloses an aluminum alloy pipe easy to process and resistant to corrosion. The aluminum alloy pipe comprises the following components in parts by weight: less than or equal to 0.2 part of Si, less than or equal to 0.12 part of Fe, less than or equal to 0.01 part of Cu, 0.6-0.9 part of Mn, less than or equal to 0.05 part of Mg, 0.1-0.3 part of Zn, 0.05-0.25 part of Cr, 0.1-0.3 part of Ti and 100 parts of Al and inevitable impurities. The aluminum alloy pipe has a fine grain structure, and the grain level can reach 6 or above; and the corrosion resistance is excellent, and after an SWAAT salt spray test, leakage can be avoided within 1000 hours. The preparation process disclosed by the invention has the advantages of simple steps, controllable conditions and low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloys, and more specifically to an easily processable and corrosion-resistant aluminum alloy tube and a preparation process thereof. Background Art

[0002] In today's lightweight era of energy conservation and emission reduction, aluminum alloy pipes are widely used in automobile pipelines due to their low density. As competition among major automobile manufacturers becomes increasingly fierce, in addition to performance requirements, pipeline design also places higher requirements on the corrosion resistance of aluminum alloy pipes, such as requiring no leakage in the SWAAT acid salt spray test (ASTM G85) for 1000 hours or more.

[0003] At present, the widely used 3003 aluminum alloy tubes and their processing technology can hardly meet the customers' increasing requirements for corrosion resistance. After the acid salt spray test, the corrosion depth of ordinary 3003 aluminum tubes is very deep. Without surface treatment, it is difficult to meet the requirement of no leakage for 1000 hours. However, surface treatment is increasingly restricted due to environmental pollution issues. At the same time, it will affect subsequent processing and the production cost is high.

[0004] Therefore, there is an urgent need for an aluminum alloy tube that is easy to process and corrosion-resistant and a preparation process thereof. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide an aluminum alloy tube that is easy to process and corrosion-resistant and a preparation process thereof, so as to solve the problems in the background technology.

[0006] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows.

[0007] An aluminum alloy tube that is easy to process and corrosion-resistant comprises the following components in parts by mass:

[0008] Si≤0.2 parts, Fe≤0.12 parts, Cu≤0.01 parts, Mn 0.6 parts-0.9 parts, Mg≤0.05 parts, Zn 0.1 parts-0.3 parts, Cr 0.05 parts-0.25 parts, Ti 0.1 parts-0.3 parts and Al and inevitable impurities constitute 100 parts.

[0009] A preparation process of an easily processable and corrosion-resistant aluminum alloy tube, 2. specifically comprising the following steps:

[0010] S1. Melting: Put the required aluminum ingot into the furnace, heat it to 730-760℃ and melt it to obtain molten aluminum liquid;

[0011] S2. Slag removal: Control the aluminum liquid temperature to 730-760℃, sprinkle the slag remover evenly into the furnace and stir it for 5-10 minutes, then use a rake to remove the slag on the surface of the aluminum liquid;

[0012] S3. Alloy: Control the temperature to 730-760°C, add Mn, Zn, Cr and Ti alloys into the furnace according to the composition ratio and stir them thoroughly for 5-10 minutes;

[0013] S4, refining: control the temperature to 750-770°C, add fluorine-free and sodium-free granular refining agent according to 1-1.5 kg / ton aluminum, use argon gas for refining for 50-55 minutes, and remove the scum on the liquid surface after refining;

[0014] S5. Casting: Control the temperature in the furnace to 750-770°C for casting into an ingot. During the casting process, add Al5Ti1B aluminum titanium boron wire online on the casting trough at a rate of 75-85 cm / min; then pass through an online degassing device and an online filtration device, and finally use a vacuum direct cooling casting system to cast to obtain an ingot with a diameter of 152 mm, with a casting speed of 155±2 mm / min;

[0015] S6, subjecting the aluminum alloy casting rod obtained by casting in step S5 to homogenization heat treatment, wherein the homogenization heat treatment temperature is 600±10° C., and the holding time is 12h+0.2h;

[0016] S7, cutting the cast rod obtained in step S6 to obtain short and long cast rods of equal length suitable for extrusion;

[0017] S8, preheating the short cast rod obtained in step S7, then preheating the die barrel and the die, and rapidly cooling, drying, oiling and coiling the short cast rod at low temperature and continuously extruding the short cast rod to obtain an aluminum alloy extruded tube blank;

[0018] S9, according to different finished product specifications, the extruded tube obtained in step S8 is coiled and drawn to produce qualified aluminum alloy coils;

[0019] S10, the aluminum alloy coil obtained in step S9 is subjected to bright online annealing by medium frequency induction heating, the annealing temperature is 480±20 degrees, the annealing speed is 100-150m / min, and after annealing, it is quickly cooled by water and then collected into a large plate;

[0020] S11, cutting the annealed tube obtained in step S10 into an aluminum alloy tube according to customer requirements.

[0021] To further optimize the technical solution, the aluminum ingot in step S1 is an aluminum ingot of grade AL99.70 in the GB / T 1196-2008 standard.

[0022] To further optimize the technical solution, the amount of slag remover added in step S2 is 0.3 kg per ton.

[0023] The technical solution is further optimized, and the argon content in step S4 is above 99.7%.

[0024] To further optimize the technical solution, in step S5, high-purity argon gas is introduced during online degassing, and the argon content is above 99.7%; double-layer filtration is used for online filtration, with a 20-inch 40ppi and a 17-inch 60ppi ceramic filter plate for filtration to further purify the melt.

[0025] To further optimize the technical solution, the length of the cast rod in step S7 is 875 mm.

[0026] To further optimize the technical solution, the preheating conditions in step S8 are as follows: the preheating temperature of the short-stock aluminum alloy round cast rod is 470°C-490°C for the head, the preheating temperature of the die barrel is 410°C-430°C, and the preheating temperature of the mold is 460°C-500°C; the forward continuous extrusion conditions are as follows: the extrusion ratio is 50-65, and the extrusion speed is 9mm / s-10mm / s; the short-stock aluminum alloy round cast rod adopts a gradient preheating method, that is, the preheating temperature of the cast rod at the advanced die barrel end is high, and the preheating temperature of the backward die barrel end is low, and the gradient is 6-10°C / 100mm.

[0027] Due to the adoption of the above technical solution, the present invention has the following beneficial effects:

[0028] 1) The present invention provides an aluminum alloy tube that is easy to process and corrosion-resistant and a preparation process thereof, wherein the aluminum alloy material is an aluminum alloy with Mn as the main element, and a certain amount of Zn, Cr, and Ti elements are added. Mn can improve the strength of the aluminum alloy tube and also refine the grains. Cr and Ti play a role in refining the grains and improving the corrosion resistance of the aluminum alloy; Zn can reduce the matrix potential difference and form a layer of Zn oxide between the cathode phase and the matrix, which plays a role in inhibiting corrosion; at the same time, the content of harmful impurities Cu, Fe, and Si is controlled at a low level, which inhibits pitting corrosion of the aluminum alloy, and can pass the 1000-hour SWAAT salt spray test without leakage.

[0029] 2) The present invention provides an aluminum alloy tube that is easy to process and corrosion-resistant, and its mechanical properties meet the requirements of tensile strength ≥95MPa, yield strength ≥35MPa, and elongation ≥35%. Its mechanical properties are better than those of 3003 aluminum alloy tubes and can replace 3003 aluminum alloy tubes.

[0030] 3) The present invention provides an aluminum alloy tube that is easy to process and corrosion-resistant. A certain amount of Mn, Cr, and Ti elements with grain refining effect are added to the alloy composition; and its preparation process adopts an online annealing process, so that the prepared aluminum alloy tube has a fine and uniform grain structure, and its grain level index can reach more than level 6.

[0031] 4) The preparation process of the present invention has the advantages of simple steps, controllable conditions and low cost.

[0032] 5) The present invention can improve the strength of the product by increasing the Mn content. Mn combined with other alloy elements can make the performance of the aluminum alloy tube equivalent to that of the 3003 aluminum alloy tube, and can also increase the elongation of the product and improve the plasticity of the product. At the same time, the present invention also increases the Zn content, which can reduce the potential difference of the aluminum matrix and form a layer of Zn oxide between the cathode phase and the matrix, which plays a role in inhibiting corrosion and further improves the corrosion resistance of the aluminum alloy tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The corrosion diagram of the acid salt spray test of Example 1 of the present invention after the SWAAT acid salt spray test (ASTM G85) was carried out for 1000 hours;

[0034] Figure 2 The corrosion diagram of the acid salt spray test of Example 2 of the present invention after the SWAAT acid salt spray test (ASTM G85) was carried out for 1000 hours;

[0035] Figure 3 The corrosion diagram of the acid salt spray test of Example 3 of the present invention after the SWAAT acid salt spray test (ASTM G85) was carried out for 1000 hours;

[0036] Figure 4 This is a grain structure detection diagram of Example 1 of the present invention;

[0037] Figure 5 This is a grain structure detection diagram of Example 2 of the present invention;

[0038] Figure 6 This is a grain structure detection diagram of Example 3 of the present invention; DETAILED DESCRIPTION

[0039] The present invention will be further described in detail below with reference to the specific embodiments of the drawings.

[0040] An easy-to-process and corrosion-resistant aluminum alloy tube, combined with Figures 1 to 6 As shown, it includes the following components in parts by weight:

[0041] Si≤0.2 parts, Fe≤0.12 parts, Cu≤0.01 parts, Mn 0.6 parts-0.9 parts, Mg≤0.05 parts, Zn 0.1 parts-0.3 parts, Cr 0.05 parts-0.25 parts, Ti 0.1 parts-0.3 parts and Al and inevitable impurities constitute 100 parts.

[0042] A preparation process of an aluminum alloy tube that is easy to process and corrosion-resistant comprises the following steps:

[0043] S1. Melting: Select aluminum ingots of AL99.70 grade in GB / T 1196-2008 standard, put the required aluminum ingots into the furnace, heat to 730-760℃ to melt, and obtain molten aluminum liquid.

[0044] S2. Slag removal: Control the aluminum liquid temperature at 730-760℃, add slag remover at the rate of 0.3kg per ton, sprinkle the slag remover evenly into the furnace and stir it thoroughly for 5-10 minutes, then use a rake to remove the slag on the surface of the aluminum liquid.

[0045] S3. Alloy: Control the temperature to 730-760℃, add Mn, Zn, Cr and Ti alloys into the furnace according to the composition ratio and stir them thoroughly for 5-10 minutes.

[0046] S4. Refining: Control the temperature to 750-770°C, add fluorine-free and sodium-free particle refining agent according to 1-1.5 kg / ton aluminum, use argon gas with a content of more than 99.7% for refining for 50-55 minutes, and remove the scum on the liquid surface after refining.

[0047] S5, Casting: Control the temperature in the furnace to 750-770℃ for casting into ingots. During the casting process, add Al5Ti1B aluminum titanium boron wire online on the casting trough at a rate of 75-85cm / min; then pass through the online degassing device and the online filtration device, and finally use the vacuum direct cooling casting system to cast to obtain an ingot with a diameter of 152mm, with a casting speed of 155±2mm / min. During the online degassing, high-purity argon gas is introduced, with an argon content of more than 99.7%; the online filtration adopts double-layer filtration, a 20-inch 40ppi and a 17-inch 60ppi ceramic filter plate to filter, to further purify the melt.

[0048] S6. Perform homogenization heat treatment on the aluminum alloy cast rod obtained by casting in step S5. The homogenization heat treatment temperature is 600±10° C. and the holding time is 12h+0.2h.

[0049] S7, cutting the cast rod obtained in step S6 to obtain short cast rods of equal length with a length of 875 mm suitable for extrusion.

[0050] S8, preheat the short cast rod obtained in step S7, then preheat the die barrel and the mold, and after low-temperature rapid continuous extrusion, quickly cool, dry, oil and roll to obtain an aluminum alloy extruded tube. Preheating conditions: the preheating temperature of the short aluminum alloy round cast rod is 470℃-490℃ for the head, the preheating temperature of the die barrel is 410℃~430℃, and the preheating temperature of the mold is 460℃~500℃. Forward continuous extrusion conditions: the extrusion ratio is 50~65, and the extrusion speed is 9mm / s~10mm / s. The short aluminum alloy round cast rod adopts a gradient preheating method, that is, the preheating temperature of the cast rod at the advanced die barrel end is high, and the preheating temperature of the backward die barrel end is low, and the gradient is 6-10℃ / 100mm.

[0051] S9. According to different finished product specifications, the extruded tube blank obtained in step S8 is coiled to produce a qualified aluminum alloy coil.

[0052] S10. The aluminum alloy coil obtained in step S9 is subjected to bright online annealing by medium frequency induction heating, the annealing temperature is 480±20 degrees, the annealing speed is 100-150m / min, and after annealing, it is quickly water-cooled and stored in a large plate.

[0053] S11, cutting the annealed tube obtained in step S10 into an aluminum alloy tube according to customer requirements.

[0054] Embodiment 1:

[0055] An aluminum alloy tube that is easy to process and corrosion-resistant comprises the following components in parts by mass:

[0056] Si 0.01 part, Fe 0.12 part, Cu 0 part, Mn 0.6 part, Mg 0.01 part, Zn 0.2 part, Cr 0.25 part, Ti 0.3 part, and the remainder is Al and unavoidable impurities, a total of 100 parts.

[0057] A preparation process of an aluminum alloy tube that is easy to process and corrosion-resistant comprises the following steps:

[0058] S1. Melting: Select aluminum ingots of AL99.70 grade in GB / T 1196-2008 standard, put the required aluminum ingots into the furnace, heat to 760℃ to melt, and obtain molten aluminum liquid.

[0059] S2. Slag removal: Control the aluminum liquid temperature to 730℃, add slag remover at the rate of 0.3kg per ton, sprinkle the slag remover evenly into the furnace and stir it thoroughly for 5 minutes, then use a rake to remove the slag on the surface of the aluminum liquid.

[0060] S3. Alloy: Control the temperature to 745°C, add Mn, Zn, Cr and Ti alloys into the furnace according to the composition ratio and stir thoroughly for 5 minutes.

[0061] S4. Refining: Control the temperature to 750°C, add fluorine-free and sodium-free particle refining agent according to 1-1.5 kg / ton aluminum, use argon gas with a content of more than 99.7% to refine for 50 minutes, and remove the scum on the liquid surface after refining.

[0062] S5, Casting: Control the temperature in the furnace to 750℃ for casting into ingots. During the casting process, add Al5Ti1B aluminum titanium boron wire online on the casting trough at a speed of 85cm / min; then pass through the online degassing device and the online filtration device, and finally use the vacuum direct cooling casting system to cast to obtain an ingot with a diameter of 152mm, with a casting speed of 155mm / min. During the online degassing, high-purity argon gas is introduced, with an argon content of more than 99.7%; the online filtration adopts double-layer filtration, a 20-inch 40ppi and a 17-inch 60ppi ceramic filter plate to filter, to further purify the melt.

[0063] S6. Perform homogenization heat treatment on the aluminum alloy cast rod obtained by casting in step S5. The homogenization heat treatment temperature is 610° C. and the holding time is 12.2 h.

[0064] S7, cutting the cast rod obtained in step S6 to obtain short cast rods of equal length with a length of 875 mm suitable for extrusion.

[0065] S8, preheat the short cast rod obtained in step S7, then preheat the die barrel and the mold, and after low-temperature rapid continuous extrusion, quickly cool, dry, oil and roll to obtain an aluminum alloy extruded tube. Preheating conditions: The preheating temperature of the short aluminum alloy round cast rod is 470°C for the head, 420°C for the die barrel, and 460°C for the mold. Forward continuous extrusion conditions: the extrusion ratio is 50 and the extrusion speed is 9mm / s. The short aluminum alloy round cast rod adopts a gradient preheating method, that is, the preheating temperature of the cast rod at the advanced die barrel end is high, and the preheating temperature of the backward die barrel end is low, and the gradient is 8°C / 100mm.

[0066] S9. According to different finished product specifications, the extruded tube blank obtained in step S8 is coiled to produce a qualified aluminum alloy coil.

[0067] S10. The aluminum alloy coil obtained in step S9 is subjected to bright online annealing by medium frequency induction heating, the annealing temperature is 460 degrees, the annealing speed is 150m / min, and after annealing, it is quickly water-cooled and stored in a large plate.

[0068] S11, cutting the annealed tube obtained in step S10 into an aluminum alloy tube according to customer requirements.

[0069] Embodiment 2:

[0070] An aluminum alloy tube that is easy to process and corrosion-resistant comprises the following components in parts by mass:

[0071] 0.2 parts of Si, 0.01 parts of Fe, 0.05 parts of Cu, 0.75 parts of Mn, 0.03 parts of Mg, 0.3 parts of Zn, 0.05 parts of Cr, 0.1 parts of Ti, and the remainder being Al and unavoidable impurities, a total of 100 parts.

[0072] A preparation process of an aluminum alloy tube that is easy to process and corrosion-resistant comprises the following steps:

[0073] S1. Melting: Select aluminum ingots of AL99.70 grade in GB / T 1196-2008 standard, put the required aluminum ingots into the furnace, heat to 745℃ to melt, and obtain molten aluminum liquid.

[0074] S2. Slag removal: Control the aluminum liquid temperature to 745℃, add slag remover at the rate of 0.3kg per ton, sprinkle the slag remover evenly into the furnace and stir it thoroughly for 8 minutes, then use a rake to remove the slag on the surface of the aluminum liquid.

[0075] S3. Alloy: Control the temperature to 760°C, add Mn, Zn, Cr and Ti alloys into the furnace according to the composition ratio and stir thoroughly for 10 minutes.

[0076] S4. Refining: Control the temperature to 760°C, add fluorine-free and sodium-free particle refining agent according to 1-1.5 kg / ton aluminum, use argon gas with a content of more than 99.7% for refining for 53 minutes, and remove the scum on the liquid surface after refining.

[0077] S5, Casting: Control the temperature in the furnace to 760℃ for casting into ingots. During the casting process, add Al5Ti1B aluminum titanium boron wire online on the casting trough at a speed of 80cm / min; then pass through the online degassing device and the online filtration device, and finally use the vacuum direct cooling casting system to cast to obtain an ingot with a diameter of 152mm, with a casting speed of 156mm / min. During the online degassing, high-purity argon gas is introduced, with an argon content of more than 99.7%; the online filtration adopts double-layer filtration, a 20-inch 40ppi and a 17-inch 60ppi ceramic filter plate to filter, to further purify the melt.

[0078] S6. Perform homogenization heat treatment on the aluminum alloy cast rod obtained by casting in step S5. The homogenization heat treatment temperature is 600° C. and the holding time is 11.8 h.

[0079] S7, cutting the cast rod obtained in step S6 to obtain short cast rods of equal length with a length of 875 mm suitable for extrusion.

[0080] S8, preheat the short cast rod obtained in step S7, then preheat the die barrel and the mold, and after low-temperature rapid continuous extrusion, quickly cool, dry, oil and roll to obtain an aluminum alloy extruded tube. Preheating conditions: The preheating temperature of the short aluminum alloy round cast rod is 480°C for the head, 410°C for the die barrel, and 480°C for the mold. Forward continuous extrusion conditions: the extrusion ratio is 65 and the extrusion speed is 9.5mm / s. The short aluminum alloy round cast rod adopts a gradient preheating method, that is, the preheating temperature of the cast rod at the advanced die barrel end is high, and the preheating temperature of the backward die barrel end is low, and the gradient is 6°C / 100mm.

[0081] S9. According to different finished product specifications, the extruded tube blank obtained in step S8 is coiled to produce a qualified aluminum alloy coil.

[0082] S10. The aluminum alloy coil obtained in step S9 is subjected to bright online annealing by medium frequency induction heating, the annealing temperature is 500 degrees, the annealing speed is 100m / min, and after annealing, it is quickly water-cooled and collected into a large plate.

[0083] S11, cutting the annealed tube obtained in step S10 into an aluminum alloy tube according to customer requirements.

[0084] Embodiment 3:

[0085] An aluminum alloy tube that is easy to process and corrosion-resistant comprises the following components in parts by mass:

[0086] 0.15 parts of Si, 0.06 parts of Fe, 0.01 parts of Cu, 0.9 parts of Mn, 0.05 parts of Mg, 0.1 parts of Zn, 0.15 parts of Cr, 0.2 parts of Ti, and the remainder being Al and unavoidable impurities, a total of 100 parts.

[0087] A preparation process of an aluminum alloy tube that is easy to process and corrosion-resistant comprises the following steps:

[0088] S1. Melting: Select aluminum ingots of AL99.70 grade in GB / T 1196-2008 standard, put the required aluminum ingots into the furnace, heat to 730℃ to melt, and obtain molten aluminum liquid.

[0089] S2. Slag removal: Control the aluminum liquid temperature to 760℃, add slag remover at the rate of 0.3kg per ton, sprinkle the slag remover evenly into the furnace and stir it thoroughly for 10 minutes, then use a rake to remove the slag on the surface of the aluminum liquid.

[0090] S3. Alloy: Control the temperature to 730°C, add Mn, Zn, Cr and Ti alloys into the furnace according to the composition ratio and stir thoroughly for 8 minutes.

[0091] S4. Refining: Control the temperature to 770°C, add fluorine-free and sodium-free granular refining agent according to 1-1.5 kg / ton aluminum, use argon gas with a content of more than 99.7% to refine for 55 minutes, and remove the scum on the liquid surface after refining.

[0092] S5, Casting: Control the temperature in the furnace to 770℃ for casting into ingots. During the casting process, add Al5Ti1B aluminum titanium boron wire online on the casting trough at a speed of 75cm / min; then pass through the online degassing device and the online filtration device, and finally use the vacuum direct cooling casting system to cast to obtain an ingot with a diameter of 152mm, with a casting speed of 157mm / min. High-purity argon gas is introduced during online degassing, with an argon content of more than 99.7%; online filtration uses double-layer filtration, a 20-inch 40ppi and a 17-inch 60ppi ceramic filter plate to filter, to further purify the melt.

[0093] S6. Perform homogenization heat treatment on the aluminum alloy cast rod obtained by casting in step S5. The homogenization heat treatment temperature is 590° C. and the holding time is 12 h.

[0094] S7, cutting the cast rod obtained in step S6 to obtain short cast rods of equal length with a length of 875 mm suitable for extrusion.

[0095] S8, preheat the short cast rod obtained in step S7, then preheat the die barrel and the mold, and after low-temperature rapid continuous extrusion, quickly cool, dry, oil and roll to obtain an aluminum alloy extruded tube. Preheating conditions: The preheating temperature of the short aluminum alloy round cast rod is 490°C for the head, 430°C for the die barrel, and 500°C for the mold. Forward continuous extrusion conditions: the extrusion ratio is 60 and the extrusion speed is 10mm / s. The short aluminum alloy round cast rod adopts a gradient preheating method, that is, the preheating temperature of the cast rod at the advanced die barrel end is high, and the preheating temperature of the backward die barrel end is low, and the gradient is 10°C / 100mm.

[0096] S9. According to different finished product specifications, the extruded tube blank obtained in step S8 is coiled to produce a qualified aluminum alloy coil.

[0097] S10. The aluminum alloy coil obtained in step S9 is subjected to bright online annealing by medium frequency induction heating, the annealing temperature is 480 degrees, the annealing speed is 125m / min, and after annealing, it is quickly cooled by water and stored in a large plate.

[0098] S11, cutting the annealed tube obtained in step S10 into an aluminum alloy tube according to customer requirements.

[0099] The aluminum alloy tubes prepared in Examples 1-3 were sampled and subjected to a 1000-hour SWAAT salt spray test (ASTM G85), grain size and performance tests, respectively, together with 3003 aluminum alloy tubes of the same size. The results are shown in Tables 1 and 2 below.

[0100] Table 1:

[0101]

[0102]

[0103] Table 2:

[0104]

[0105] It can be seen from Table 1 that the corrosion resistance of the aluminum alloy tube prepared in the present invention is better than that of 3003, and there is no leakage after a 1000-hour SWAAT salt spray test, and the corrosion depth is only 0.18-0.23 mm.

[0106] It can be seen from Table 2 that the aluminum alloy tube prepared by the present invention has better tensile strength, yield strength and elongation than 3003, and has a higher grain grade than 3003.

[0107] In summary, the aluminum alloy tube prepared by the present invention has the advantages of easy processing, fine and uniform grain structure, and good corrosion resistance.

Claims

1. An easily processable and corrosion-resistant aluminum alloy tube, characterized in that: The composition includes the following components in parts by weight: Si≤0.2 parts, Fe≤0.12 parts, Cu≤0.01 parts, Mn 0.6 parts-0.9 parts, Mg≤0.05 parts, Zn 0.1 parts-0.3 parts, Cr 0.05 parts-0.25 parts, Ti 0.1 parts-0.3 parts and Al and inevitable impurities constitute 100 parts.

2. A process for preparing an easily processable and corrosion-resistant aluminum alloy tube as claimed in claim 1, characterized in that: The specific steps include: S1. Melting: Put the required aluminum ingot into the furnace, heat it to 730-760℃ and melt it to obtain molten aluminum liquid; S2. Slag removal: Control the aluminum liquid temperature to 730-760℃, sprinkle the slag remover evenly into the furnace and stir it for 5-10 minutes, then use a rake to remove the slag on the surface of the aluminum liquid; S3. Alloy: Control the temperature to 730-760°C, add Mn, Zn, Cr and Ti alloys into the furnace according to the composition ratio and stir them thoroughly for 5-10 minutes; S4, refining: control the temperature to 750-770°C, add fluorine-free and sodium-free granular refining agent according to 1-1.5 kg / ton aluminum, use argon gas for refining for 50-55 minutes, and remove the scum on the liquid surface after refining; S5. Casting: Control the temperature in the furnace to 750-770°C for casting into an ingot. During the casting process, add Al5Ti1B aluminum titanium boron wire online on the casting trough at a rate of 75-85 cm / min; then pass through an online degassing device and an online filtration device, and finally use a vacuum direct cooling casting system to cast to obtain an ingot with a diameter of 152 mm, with a casting speed of 155±2 mm / min; S6, subjecting the aluminum alloy casting rod obtained by casting in step S5 to homogenization heat treatment, wherein the homogenization heat treatment temperature is 600±10° C. and the holding time is 12h+0.2h; S7, cutting the cast rod obtained in step S6 to obtain short and long cast rods of equal length suitable for extrusion; S8, preheating the short cast rod obtained in step S7, then preheating the die barrel and the die, and rapidly cooling, drying, oiling and coiling the short cast rod at low temperature and continuously extruding the short cast rod to obtain an aluminum alloy extruded tube blank; S9, according to different finished product specifications, the extruded tube obtained in step S8 is coiled and drawn to produce qualified aluminum alloy coils; S10, the aluminum alloy coil obtained in step S9 is subjected to bright online annealing by medium frequency induction heating, the annealing temperature is 480±20 degrees, the annealing speed is 100-150m / min, and after annealing, it is quickly water-cooled and stored in a large plate; S11, cutting the annealed tube obtained in step S10 into an aluminum alloy tube according to customer requirements.

3. The easily processable and corrosion-resistant aluminum alloy tube and its preparation process according to claim 2, characterized in that: In the step S1, the aluminum ingot is an aluminum ingot of grade AL99.70 in the GB / T 1196-2008 standard.

4. The easily processable and corrosion-resistant aluminum alloy tube and its preparation process according to claim 2, characterized in that: The amount of slag remover added in step S2 is 0.3 kg per ton.

5. The easily processable and corrosion-resistant aluminum alloy tube and its preparation process according to claim 2, characterized in that: The argon content in step S4 is above 99.7%.

6. The easily processable and corrosion-resistant aluminum alloy tube and its preparation process according to claim 2, characterized in that: In the step S5, high-purity argon gas is introduced during online degassing, and the argon content is more than 99.7%; The online filtration uses double-layer filtration, a 20-inch 40ppi and a 17-inch 60ppi ceramic filter plate to further purify the melt.

7. The easily processable and corrosion-resistant aluminum alloy tube and its preparation process according to claim 2, characterized in that: The length of the cast rod in step S7 is 875 mm.

8. The easily processable and corrosion-resistant aluminum alloy tube and its preparation process according to claim 2, characterized in that: The preheating conditions in step S8 are as follows: the preheating temperature of the short aluminum alloy round cast rod is 470°C-490°C for the head, the preheating temperature of the die barrel is 410°C-430°C, and the preheating temperature of the mold is 460°C-500°C; the forward continuous extrusion conditions are as follows: the extrusion ratio is 50-65, and the extrusion speed is 9mm / s-10mm / s; the short aluminum alloy round cast rod adopts a gradient preheating method, that is, the preheating temperature of the cast rod at the advanced die barrel end is high, and the preheating temperature of the backward die barrel end is low, and the gradient is 6-10°C / 100mm.

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