High-temperature-resistant high-strength soluble aluminum alloy pipe and preparation method thereof

Abstract

The invention discloses a high-temperature-resistant and high-strength soluble aluminum alloy pipe and a preparation method thereof. The preparation method comprises the steps that firstly, metal raw materials are selected according to components of a target product to be weighed; 2, graded heating smelting and water-cooling mold casting are carried out; 3, cutting off a dead head after uniform annealing, turning, and forming a central through hole; fourthly, hot extrusion forming is conducted; and 5, solid solution aging treatment. By reasonably proportioning the contents of strengthening elements such as Mg, Zn, Cu, Fe, Cr, Si and Mn and functional elements such as Ga, In and Sn in the aluminum alloy and combining extrusion large deformation and solid solution aging heat treatment, multiple strengthening mechanisms including solid solution strengthening, precipitation strengthening and grain boundary strengthening play a synergistic strengthening role, controlled degradation of the soluble aluminum alloy material in an ultrahigh-temperature and ultrahigh-pressure environment is achieved, and the degradation rate of the soluble aluminum alloy material in the ultrahigh-temperature and ultrahigh-pressure environment is improved. And moreover, the steel has higher tensile strength in a superhigh-temperature environment, meets the working conditions of superhigh temperature and superhigh pressure, and is suitable for the field of oil-gas field exploitation pipelines in the petroleum industry.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas field development in the petroleum industry, and specifically relates to a high-temperature resistant, high-strength, soluble aluminum alloy pipe and a preparation method thereof. Background Art

[0002] The demand for soluble materials in the field of oil and gas drilling and production tools is increasing, especially for soluble pipes, soluble packers and other components, which not only require the materials to have excellent formability, but also face ultra-high temperature (170℃~250℃) and ultra-high pressure (>200MPa) environments during service, which also put forward more stringent requirements on the mechanical properties of materials. At present, soluble polymer materials, soluble ceramic materials, etc. still have disadvantages such as high cost, difficulty in preparing large-sized and complex-shaped components, and low high-temperature strength. Although magnesium alloys have excellent solubility, their processing and forming capabilities are poor, the dissolution rate control is difficult, and they have not yet achieved real engineering applications. In contrast, aluminum alloys have low density, good formability, excellent high-temperature strength, and great potential for solubility regulation. They have great application prospects in the preparation of key soluble components in the field of oil and gas drilling and production.

[0003] The document "Wang MF, Xiao DH, Sun BR, et al. Microstructure, mechanical properties and corrosion behavior of Al-Cu-Mg-Sn-Ga-In alloy. Journal of Alloys and Compounds, 2019, 776: 172-180." discloses a soluble aluminum alloy with high compressive strength of 582 MPa. However, the document only carried out the preparation of alloy ingots and precipitation phase analysis, and did not involve alloy plasticity research, let alone the preparation of thin-walled complex components such as pipes, which is still some distance away from engineering realization.

[0004] The three invention patents of Shaanxi University of Science and Technology, CN114752827A "A low-temperature soluble aluminum alloy and its use", CN114717456A "A high-temperature soluble aluminum alloy, preparation method and use" and CN114686734A "A high-ductility soluble aluminum alloy, preparation method and use", all designed Al-Mg-Ga-In-Sn system soluble aluminum alloys, realizing the controlled dissolution of materials in the temperature range of room temperature to 90°C. The invention patent CN116005046A of Central South University "A high-elongation soluble aluminum alloy and its preparation method and application" announced the soluble aluminum alloy of the Al-Mg-Cu-Ga-In-Sn system, achieving both rapid dissolution and moderate room temperature strength. However, the strengthening elements of the soluble aluminum alloys covered by these patents are few in type and low in content, and none of them involve research on the mechanical properties and solubility of materials in the ultra-high temperature range of 170°C to 250°C. In addition, the soluble aluminum alloys designed in these patents have limited formability and can only be produced into rods through a small extrusion ratio of less than 20, and do not involve the preparation of tubes with a higher extrusion ratio.

[0005] In the invention patent CN115637357A "A Soluble Aluminum Alloy" of China National Petroleum Corporation, a soluble aluminum alloy of Al-Mg-Ga-In series for hydraulic fracturing operations is designed. Its solubility can match that of clean water or at least low-mineralization fluids, and its room temperature tensile strength is as high as 240MPa. However, the plasticity of the alloy is only 2.6%, making it difficult to deform into thin-walled complex components such as pipes. In the invention patent CN105950920A "A Soluble Aluminum-Based Alloy in Water and Aqueous Medium Environment and Its Preparation Method" of the Institute of Metal Research, Chinese Academy of Sciences, a soluble aluminum alloy of Al-Mg-Cu-Ti-Ga-In-Sn series is designed. The initial reaction temperature and dissolution rate in water and aqueous medium environments can be controlled, and it can be used to prepare a variety of oil well fracturing tools. However, the strength of the alloy is designed for casting, and the room temperature strength is high, but the compressive strain is less than 30%, which limits the processing of complex components with large deformation.

[0006] In summary, existing soluble aluminum alloys only meet the low-temperature solubility performance below 90°C, and cannot meet the use conditions of ultra-high temperature, ultra-high pressure and ultra-deep well environments. In addition, soluble aluminum alloys are currently mainly used in the engineering field to prepare simple fracturing tools. The elongation of their materials is relatively low, and it is difficult to prepare complex components such as pipes by large deformation. Therefore, the key to the design of new soluble aluminum alloys is to reasonably design the ratio of each element and the forming process parameters of the soluble aluminum alloy material, to achieve high extrusion ratio extrusion deformation preparation of large-sized components such as pipes, and to have both controllable solubility and excellent mechanical properties under ultra-high temperature and ultra-high pressure complex working conditions. Therefore, it is urgent to develop a high-temperature resistant and high-strength soluble aluminum alloy pipe and its preparation method to achieve a wide range of engineering applications. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a high-temperature resistant and high-strength soluble aluminum alloy in view of the deficiencies of the above-mentioned prior art. The method reasonably proportions the strengthening elements such as Mg, Zn, Cu, Fe, Cr, Si, Mn and the functional elements Ga, In and Sn in the aluminum alloy, combines the extrusion large deformation and solid solution aging heat treatment, so that multiple strengthening mechanisms including solid solution strengthening, precipitation strengthening and grain boundary strengthening play a synergistic strengthening role, realizes the controlled degradation of the soluble aluminum alloy material in an ultra-high temperature and ultra-high pressure environment, and has a high tensile strength in an ultra-high temperature environment, solving the problem that the existing soluble aluminum alloy has poor solubility at high temperature and poor plasticity and is difficult to be prepared into complex components such as pipes through large deformation.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing a high-temperature resistant, high-strength soluble aluminum alloy pipe, characterized in that the method comprises the following steps:

[0009] Step 1, weighing: according to the mass percentage composition of the target product soluble aluminum alloy pipe, metal raw materials are selected for weighing: Mg 1.0%-4.0%, Zn 2.5%-7.0%, Cu 0.1%-3%, Fe 0.1%-0.5%, Cr0.1%-0.4%, Si 0.1%-0.9%, Mn 0.05%-0.2%, Ga0.5%-1.5%, In 0.5%-1.5%, Sn 0.5%-1.5%, the balance is Al and inevitable impurity elements, and Al and Zn elements in each component are introduced in the form of raw materials of single metals, and Mg, Cu, Fe, Cr, Si, and Mn elements are introduced in the form of raw materials of AlMg10 master alloy, AlCu50 master alloy, AlFe20 master alloy, AlCr5 master alloy, AlSi20 master alloy, and AlMn10 master alloy, respectively;

[0010] Step 2, smelting and casting: first, melt the Al single metal raw material in the metal raw material weighed in step 1 until it is completely melted, then heat it to 750°C to 770°C and add Ga, In, and Sn, stir and keep warm for 10 minutes to ensure that the metal raw materials are completely melted and stirred evenly, then heat it to 830°C to 850°C and add Zn single metal raw material, AlMg10 master alloy, AlCu50 master alloy, AlFe20 master alloy, AlCr5 master alloy, AlSi20 master alloy, and AlMn10 master alloy, stir and keep warm for 30min to 50min to ensure that the metal raw materials and the master alloy are completely melted to obtain an aluminum alloy melt, remove the scum on the surface of the aluminum alloy melt, add Al5TiB grain refiner and keep warm for 30mi to 50min, cool it to 740°C to 770°C with the furnace, cast it into a mold, cool it to room temperature and demold it to obtain a soluble aluminum alloy base material ingot;

[0011] Step 3, uniform annealing and billet processing: the soluble aluminum alloy base material ingot obtained in step 2 is subjected to uniform annealing, the riser is cut off after furnace cooling, and surface defects are removed by turning to obtain a billet with a smooth surface, and then a through hole is processed in the center of the billet by a drilling machine to obtain a billet to be extruded;

[0012] Step 4: hot extrusion molding: select a 1250-ton extruder, heat the extrusion blank obtained in step 3, and quickly load it into the preheated extruder sleeve for hot extrusion molding to obtain a soluble aluminum alloy tube blank;

[0013] Step 5: Solution aging treatment: The soluble aluminum alloy tube blank obtained in step 4 is first solution treated, air cooled to room temperature, then aged, and air cooled to room temperature to obtain a soluble aluminum alloy tube; the soluble aluminum alloy tube has a tensile strength of up to 370 MPa at 175°C.

[0014] The above-mentioned method for preparing a high-temperature resistant, high-strength soluble aluminum alloy pipe is characterized in that the mass of the Al5TiB grain refiner added in step 2 is 0.7% of the mass of the aluminum alloy melt, and the material of the mold is water-cooled 304 stainless steel.

[0015] The above-mentioned method for preparing a high-temperature resistant, high-strength soluble aluminum alloy pipe is characterized in that the temperature of the homogenization annealing in step three is 490° C. and the holding time is 2.5 hours.

[0016] The above-mentioned method for preparing a high-temperature resistant, high-strength soluble aluminum alloy pipe is characterized in that the billet to be extruded in step 4 is heated to 420°C to 490°C, and the sleeve of the extruder is preheated to 390°C; the extrusion speed of the hot extrusion molding is 20mm / min to 50mm / min, and the extrusion ratio is 10 to 35. These parameters ensure the smooth progress of the hot extrusion molding process.

[0017] The above-mentioned method for preparing a high-temperature resistant and high-strength soluble aluminum alloy pipe is characterized in that the size of the soluble aluminum alloy base material ingot in step 2 is Ф150mm×265mm in diameter × height; the size of the billet to be extruded in step 3 is an outer diameter of 115mm, an inner diameter of 50mm, and a length of 200mm; the outer diameter of the soluble aluminum alloy tube billet in step 4 is 53mm~60mm, and the inner diameter is 50mm.

[0018] The above-mentioned method for preparing a high-temperature resistant, high-strength soluble aluminum alloy pipe is characterized in that the temperature of the solid solution treatment in step five is 440°C to 530°C, and the insulation time is 1h to 2h; the temperature of the aging treatment is 100°C to 180°C, and the insulation time is 8h to 24h.

[0019] At the same time, the present invention also discloses a high-temperature resistant and high-strength soluble aluminum alloy pipe, which is characterized in that it is prepared by the above method.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1. The aluminum alloy of the present invention has a reasonable proportion of strengthening elements such as Mg, Zn, Cu, Fe, Cr, Si, and Mn, and adds soluble functional elements Ga, In, and Sn during the smelting process. The strengthening elements are dissolved into the aluminum matrix, thereby ensuring the solid solution strengthening foundation of the aluminum alloy. Combined with the grain boundary strengthening induced by large extrusion deformation and the precipitation strengthening induced by solid solution aging heat treatment, a variety of strengthening mechanisms are formed, so that solid solution strengthening, precipitation strengthening, and grain boundary strengthening play a synergistic strengthening role, and the controlled degradation of the soluble aluminum alloy material in an ultra-high temperature and ultra-high pressure environment is achieved. In addition, the aluminum alloy has a high tensile strength in an ultra-high temperature environment, that is, it still has excellent strength in an ultra-high temperature environment exceeding 170°C, wherein the tensile strength at 175°C is as high as 370MPa, which meets the ultra-high temperature and ultra-high pressure working conditions and is suitable for the field of oil and gas field production pipelines in the petroleum industry.

[0022] 2. The present invention adds functional elements Ga, In and Sn for regulation during the preparation process. Ga, In and Sn can form In3Sn and InSn4 second phases, destroying the aluminum oxide film, allowing the aluminum alloy to be continuously dissolved, breaking through the structural function inversion contradiction between strength and solubility of traditional soluble alloys, and still having a controllable dissolution rate at high temperature, wherein the mass dissolution rate in a neutral medium at 100°C is 0.2% / min to 1% / min.

[0023] 3. The aluminum alloy of the present invention adds strengthening elements and fewer functional elements, which reduces the loss of the original performance of the aluminum alloy, ensures that the aluminum alloy has excellent room temperature / high temperature plasticity, the room temperature tensile elongation at break is greater than 18%, and the 175°C elongation at break is greater than 20%, thereby ensuring that the aluminum alloy has excellent extrusion forming ability, and thin-walled components such as aluminum alloy pipes are obtained by hot extrusion forming.

[0024] 4. The preparation process of the present invention adopts a method combining graded temperature rising smelting and water-cooled mold casting, which effectively controls the metallurgical defects of the smelting ingot, so that there is no obvious shrinkage cavity and shrinkage in the soluble aluminum alloy base material ingot, thereby improving the quality of the high-temperature resistant and high-strength soluble aluminum alloy.

[0025] In summary, the present invention realizes structural and functional integration by rationally designing the ratio of each element in the soluble aluminum alloy material and the forming process, so that the aluminum alloy has both controllable solubility and excellent mechanical properties under ultra-high temperature and ultra-high pressure complex working conditions, and has excellent formability, thus realizing the large deformation preparation of large-size thin-walled complex components such as aluminum alloy pipes.

[0026] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1a This is a macroscopic morphology of the tube body of the soluble aluminum alloy tube prepared in Example 1 of the present invention.

[0028] Figure 1b This is a macroscopic morphology of the end surface of the soluble aluminum alloy tube prepared in Example 1 of the present invention.

[0029] Figure 2 This is a microstructure diagram of the soluble aluminum alloy tube prepared in Example 1 of the present invention.

[0030] Figure 3 This is a room temperature tensile curve of the soluble aluminum alloy tube prepared in Example 1 of the present invention.

[0031] Figure 4 This is a room temperature tensile curve of the soluble aluminum alloy tube prepared in Example 1 of the present invention at 175°C.

[0032] Figure 5 This is a room temperature tensile curve of the soluble aluminum alloy tube prepared in Example 1 of the present invention at 200°C.

[0033] Figure 6 This is a graph showing the change in dissolution mass ratio of the soluble aluminum alloy pipes prepared in Examples 1 to 3 of the present invention in a KCl solution with a high temperature of 100° C. and a mass concentration of 3% over time. DETAILED DESCRIPTION

[0034] Example 1

[0035] This embodiment includes the following steps:

[0036] Step 1, weighing: according to the mass percentage composition of the target product soluble aluminum alloy pipe, metal raw materials are selected for weighing: Mg 2.5%, Zn 7.0%, Cu 1.5%, Fe 0.5%, Cr 0.2%, Si 0.1%, Mn 0.2%, Ga 0.8%, In 0.8%, Sn 0.8%, the balance is Al and inevitable impurity elements, and the Al and Zn elements in each component are introduced in the form of raw materials of single metals, and the Mg, Cu, Fe, Cr, Si, and Mn elements are introduced in the form of raw materials of AlMg10 master alloy, AlCu50 master alloy, AlFe20 master alloy, AlCr5 master alloy, AlSi20 master alloy, and AlMn10 master alloy, respectively;

[0037] Step 2, smelting and casting: first, melt the Al single metal raw material in the metal raw material weighed in step 1 until it is completely melted, then heat it to 770°C and add Ga, In, and Sn, stir and keep warm for 10 minutes to ensure that the metal raw materials are completely melted and stirred evenly, then heat it to 850°C and add Zn single metal raw material, AlMg10 master alloy, AlCu50 master alloy, AlFe20 master alloy, AlCr5 master alloy, AlSi20 master alloy, AlMn10 The intermediate alloy is stirred and kept warm for 30 minutes to ensure that the metal raw materials and the intermediate alloy are completely melted to obtain an aluminum alloy melt. After removing the scum on the surface of the aluminum alloy melt, an Al5TiB grain refiner is added and kept warm for 30 minutes. After cooling to 740°C with the furnace, it is cast into a water-cooled 304 stainless steel mold, and demolded after cooling to room temperature to obtain a soluble aluminum alloy parent material ingot with a diameter × height of Ф150mm×265mm; the added mass of the Al5TiB grain refiner is 0.7% of the mass of the aluminum alloy melt;

[0038] Step 3, uniform annealing and billet processing: the soluble aluminum alloy base material ingot obtained in step 2 is heated to 490°C and kept at this temperature for 2.5 hours for homogenization annealing, the riser is cut off after furnace cooling, and surface defects are removed by turning to obtain a billet with a smooth surface, and then a through hole is processed in the center of the billet by a drilling machine to obtain a billet to be extruded with an outer diameter of 115 mm, an inner diameter of 50 mm, and a length of 200 mm;

[0039] Step 4, hot extrusion molding: select a 1250-ton extruder, heat the extruded billet obtained in step 3 to 450°C, and then quickly load it into the extruder sleeve preheated to 390°C for hot extrusion molding. The extrusion speed is 40 mm / min, and the extrusion ratio is 20, so as to obtain a soluble aluminum alloy tube billet with an outer diameter of 55 mm and an inner diameter of 50 mm;

[0040] Step 5: Solution aging treatment: The soluble aluminum alloy tube blank obtained in step 4 is first subjected to solution treatment by being kept at 490°C for 2 hours, air-cooled to room temperature, and then subjected to aging treatment by being kept at 120°C for 24 hours, and air-cooled to room temperature to obtain a soluble aluminum alloy tube.

[0041] Figure 1a and Figure 1b They are respectively the tube body and end face macroscopic morphology pictures of the soluble aluminum alloy tube prepared in this embodiment. As can be seen from FIG1 , the surface of the soluble aluminum alloy tube has no obvious defects and the wall thickness is uniform.

[0042] Figure 2 The microstructure of the soluble aluminum alloy tube prepared in this embodiment is shown in FIG. Figure 2It can be seen that the average grain size of the soluble aluminum alloy tube is 150 μm, and a strip-shaped micron-sized low-melting-point second phase is distributed at the grain boundary, which is beneficial to promoting the hydrolysis reaction of the aluminum alloy.

[0043] Figure 3 This is the room temperature tensile curve of the soluble aluminum alloy tube prepared in this embodiment. Figure 3 It can be seen that the room temperature tensile strength of the soluble aluminum alloy pipe is as high as 475MPa, and the elongation at break is 17%.

[0044] Figure 4 This is the room temperature tensile curve of the soluble aluminum alloy tube prepared in this embodiment at 175°C. Figure 4 It can be seen that the room temperature tensile strength of the soluble aluminum alloy pipe at 175°C is as high as 370 MPa, and the elongation at break is 24.7%.

[0045] Figure 5 The room temperature tensile curve of the soluble aluminum alloy tube prepared in this embodiment at 200°C is shown in FIG. Figure 5 It can be seen that the room temperature tensile strength of the soluble aluminum alloy pipe at 200°C is as high as 285MPa, and the elongation at break is 18.5%.

[0046] Example 2

[0047] This embodiment includes the following steps:

[0048] Step 1, weighing: select metal raw materials for weighing according to the mass percentage composition of the target product soluble aluminum alloy pipe: Mg 1.0%, Zn 2.5%, Cu 0.1%, Fe 0.4%, Cr 0.1%, Si 0.5%, Mn 0.1%, Ga 1.5%, In 1.5%, Sn 1.5%, the balance is Al and inevitable impurity elements, and the Al and Zn elements in each component are introduced in the form of raw materials of single metals, and the Mg, Cu, Fe, Cr, Si, and Mn elements are introduced in the form of raw materials of AlMg10 master alloy, AlCu50 master alloy, AlFe20 master alloy, AlCr5 master alloy, AlSi20 master alloy, and AlMn10 master alloy, respectively;

[0049] Step 2, smelting and casting: first, melt the Al single metal raw material in the metal raw material weighed in step 1 until it is completely melted, then heat it to 760°C and add Ga, In, and Sn, stir and keep warm for 10 minutes to ensure that the metal raw materials are completely melted and stirred evenly, then heat it to 840°C and add Zn single metal raw material, AlMg10 master alloy, AlCu50 master alloy, AlFe20 master alloy, AlCr5 master alloy, AlSi20 master alloy, AlMn10 The intermediate alloy is stirred and kept warm for 40 minutes to ensure that the metal raw materials and the intermediate alloy are completely melted to obtain an aluminum alloy melt. After removing the scum on the surface of the aluminum alloy melt, an Al5TiB grain refiner is added and kept warm for 40 minutes. After cooling to 750°C with the furnace, it is cast into a water-cooled 304 stainless steel mold, and demolded after cooling to room temperature to obtain a soluble aluminum alloy parent material ingot with a diameter×height of Ф150mm×265mm; the added mass of the Al5TiB grain refiner is 0.7% of the mass of the aluminum alloy melt;

[0050] Step 3, uniform annealing and billet processing: the soluble aluminum alloy base material ingot obtained in step 2 is heated to 490°C and kept at this temperature for 2.5 hours for homogenization annealing, the riser is cut off after furnace cooling, and surface defects are removed by turning to obtain a billet with a smooth surface, and then a through hole is processed in the center of the billet by a drilling machine to obtain a billet to be extruded with an outer diameter of 115 mm, an inner diameter of 50 mm, and a length of 200 mm;

[0051] Step 4, hot extrusion molding: select a 1250-ton extruder, heat the extruded billet obtained in step 3 to 420°C, and then quickly load it into the extruder sleeve preheated to 390°C for hot extrusion molding. The extrusion speed is 50 mm / min, and the extrusion ratio is 10, so as to obtain a soluble aluminum alloy tube billet with an outer diameter of 60 mm and an inner diameter of 50 mm;

[0052] Step 5: Solution aging treatment: The soluble aluminum alloy tube blank obtained in step 4 is first subjected to solution treatment at 440°C for 1 hour, air-cooled to room temperature, then subjected to aging treatment at 100°C for 8 hours, and air-cooled to room temperature to obtain a soluble aluminum alloy tube.

[0053] After testing, the room temperature tensile strength of the soluble aluminum alloy pipe prepared in this embodiment is as high as 410MPa, and the elongation at break is 11%. The room temperature tensile strength at 175°C is as high as 304MPa, and the elongation at break is 17%. The room temperature tensile strength at 200°C is as high as 267MPa, and the elongation at break is 18%.

[0054] Example 3

[0055] This embodiment includes the following steps:

[0056] Step 1, weighing: select metal raw materials for weighing according to the mass percentage composition of the target product soluble aluminum alloy pipe: Mg 4.0%, Zn 4.0%, Cu 3.0%, Fe 0.1%, Cr 0.4%, Si 0.9%, Mn 0.05%, Ga 0.5%, In 0.5%, Sn 0.5%, the balance is Al and inevitable impurity elements, and the Al and Zn elements in each component are introduced in the form of raw materials of single metals, and the Mg, Cu, Fe, Cr, Si, and Mn elements are introduced in the form of raw materials of AlMg10 master alloy, AlCu50 master alloy, AlFe20 master alloy, AlCr5 master alloy, AlSi20 master alloy, and AlMn10 master alloy, respectively;

[0057] Step 2, smelting and casting: first, melt the Al single metal raw material in the metal raw material weighed in step 1 until it is completely melted, then heat it to 750°C and add Ga, In, and Sn, stir and keep warm for 10 minutes to ensure that the metal raw materials are completely melted and stirred evenly, then heat it to 830°C and add Zn single metal raw material, AlMg10 master alloy, AlCu50 master alloy, AlFe20 master alloy, AlCr5 master alloy, AlSi20 master alloy, AlMn10 The intermediate alloy is stirred and kept warm for 50 minutes to ensure that the metal raw materials and the intermediate alloy are completely melted to obtain an aluminum alloy melt. After removing the scum on the surface of the aluminum alloy melt, an Al5TiB grain refiner is added and kept warm for 50 minutes. After cooling to 740°C with the furnace, it is cast into a water-cooled 304 stainless steel mold, and demolded after cooling to room temperature to obtain a soluble aluminum alloy parent material ingot with a diameter×height of Ф150mm×265mm; the added mass of the Al5TiB grain refiner is 0.7% of the mass of the aluminum alloy melt;

[0058] Step 3, uniform annealing and billet processing: the soluble aluminum alloy base material ingot obtained in step 2 is heated to 490°C and kept at this temperature for 2.5 hours for homogenization annealing, the riser is cut off after furnace cooling, and surface defects are removed by turning to obtain a billet with a smooth surface, and then a through hole is processed in the center of the billet by a drilling machine to obtain a billet to be extruded with an outer diameter of 115 mm, an inner diameter of 50 mm, and a length of 200 mm;

[0059] Step 4, hot extrusion molding: select a 1250-ton extruder, heat the extruded billet obtained in step 3 to 490°C, and then quickly load it into the extruder sleeve preheated to 390°C for hot extrusion molding. The extrusion speed is 20 mm / min, and the extrusion ratio is 35, to obtain a soluble aluminum alloy tube billet with an outer diameter of 53 mm and an inner diameter of 50 mm;

[0060] Step 5: Solution aging treatment: The soluble aluminum alloy tube blank obtained in step 4 is first subjected to solution treatment by being kept at 530°C for 1 hour, air-cooled to room temperature, and then subjected to aging treatment by being kept at 160°C for 14 hours, and air-cooled to room temperature to obtain a soluble aluminum alloy tube.

[0061] After testing, the room temperature tensile strength of the soluble aluminum alloy pipe prepared in this embodiment is as high as 460MPa, and the elongation at break is 16%. The room temperature tensile strength at 175°C is as high as 344MPa, and the elongation at break is 22%. The room temperature tensile strength at 200°C is as high as 315MPa, and the elongation at break is 20%.

[0062] Figure 6 The graph of the dissolution mass ratio of the soluble aluminum alloy pipes prepared in Examples 1 to 3 of the present invention in a KCl solution with a mass concentration of 3% at a high temperature of 100°C is shown as a function of time. Figure 6 It can be seen that the mass dissolution rate of the soluble aluminum alloy pipes prepared in Examples 1 to 3 of the present invention in a neutral medium at 100° C. is 0.2% / min to 1% / min.

[0063] In summary, the high-temperature resistant and high-strength soluble aluminum alloy prepared by the present invention has high tensile strength in an ultra-high temperature environment, that is, it still has excellent strength in an ultra-high temperature environment exceeding 170°C, wherein the tensile strength is as high as 370MPa at 175°C. At the same time, it still has a controllable dissolution rate at high temperature, thereby realizing the controlled degradation of the soluble aluminum alloy material in an ultra-high temperature and ultra-high pressure environment, realizing structural and functional integration, and having excellent formability, and can be used for thin-walled complex components such as oil and gas field production pipelines in the petroleum industry.

[0064] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a high-temperature resistant, high-strength, soluble aluminum alloy pipe, characterized in that: The method comprises the following steps: Step 1, weighing: according to the mass percentage composition of the target product soluble aluminum alloy pipe, metal raw materials are selected for weighing: Mg 1.0%-4.0%, Zn 2.5%-7.0%, Cu 0.1%-3%, Fe 0.1%-0.5%, Cr0.1%-0.4%, Si 0.1%-0.9%, Mn 0.05%-0.2%, Ga0.5%-1.5%, In 0.5%-1.5%, Sn 0.5%-1.5%, the balance is Al and inevitable impurity elements, and Al and Zn elements in each component are introduced in the form of raw materials of single metals, and Mg, Cu, Fe, Cr, Si, and Mn elements are introduced in the form of raw materials of AlMg10 master alloy, AlCu50 master alloy, AlFe20 master alloy, AlCr5 master alloy, AlSi20 master alloy, and AlMn10 master alloy, respectively; Step 2, smelting and casting: first, melt the Al single metal raw material in the metal raw material weighed in step 1 until it is completely melted, then heat it to 750°C to 770°C and add Ga, In, and Sn, stir and keep warm for 10 minutes to ensure that the metal raw materials are completely melted and stirred evenly, then heat it to 830°C to 850°C and add Zn single metal raw material, AlMg10 master alloy, AlCu50 master alloy, AlFe20 master alloy, AlCr5 master alloy, AlSi20 master alloy, and AlMn10 master alloy, stir and keep warm for 30min to 50min to ensure that the metal raw materials and the master alloy are completely melted to obtain an aluminum alloy melt, remove the scum on the surface of the aluminum alloy melt, add Al5TiB grain refiner and keep warm for 30min to 50min, cool it to 740°C to 770°C with the furnace, cast it into a mold, cool it to room temperature and demold it to obtain a soluble aluminum alloy parent material ingot; Step 3, uniform annealing and billet processing: the soluble aluminum alloy base material ingot obtained in step 2 is subjected to uniform annealing, the riser is cut off after furnace cooling, and surface defects are removed by turning to obtain a billet with a smooth surface, and then a through hole is processed in the center of the billet by a drilling machine to obtain a billet to be extruded; Step 4: hot extrusion molding: select a 1250-ton extruder, heat the extrusion blank obtained in step 3, and quickly load it into the preheated extruder sleeve for hot extrusion molding to obtain a soluble aluminum alloy tube blank; Step 5: Solution aging treatment: The soluble aluminum alloy tube blank obtained in step 4 is first solution treated, air cooled to room temperature, then aged, and air cooled to room temperature to obtain a soluble aluminum alloy tube; the soluble aluminum alloy tube has a tensile strength of up to 370 MPa at 175°C.

2. The method for preparing a high-temperature resistant, high-strength, soluble aluminum alloy pipe according to claim 1, characterized in that: In step 2, the mass of the Al5TiB grain refiner added is 0.7% of the mass of the aluminum alloy melt, and the material of the mold is water-cooled 304 stainless steel.

3. The method for preparing a high-temperature resistant, high-strength, soluble aluminum alloy pipe according to claim 1, characterized in that: The temperature of the homogenization annealing in step 3 is 490° C., and the holding time is 2.5 h.

4. The method for preparing a high-temperature resistant, high-strength, soluble aluminum alloy pipe according to claim 1, characterized in that: In step 4, the billet to be extruded is heated to 420° C. to 490° C., and the sleeve of the extruder is preheated to 390° C.; the extrusion speed of the hot extrusion molding is 20 mm / min to 50 mm / min, and the extrusion ratio is 10 to 35.

5. The method for preparing a high temperature resistant, high strength, soluble aluminum alloy pipe according to claim 1, characterized in that: The size of the soluble aluminum alloy base material ingot in step 2 is Ф150mm×265mm in diameter × height; the size of the billet to be extruded in step 3 is an outer diameter of 115mm, an inner diameter of 50mm, and a length of 200mm; the outer diameter of the soluble aluminum alloy tube billet in step 4 is 53mm~60mm, and the inner diameter is 50mm.

6. The method for preparing a high temperature resistant, high strength, soluble aluminum alloy pipe according to claim 1, characterized in that: In step 5, the temperature of the solution treatment is 440°C to 530°C, and the holding time is 1h to 2h; the temperature of the aging treatment is 100°C to 180°C, and the holding time is 8h to 24h.

7. A high-temperature resistant, high-strength, soluble aluminum alloy pipe, characterized in that: The method is prepared by any one of claims 1 to 6.

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