Aluminum alloy, method for producing the same, and seamless pipe for oil drilling rod

Abstract

The application provides an aluminum alloy and a preparation method thereof and a seamless pipe for oil drilling rods, wherein the aluminum alloy is composed of Si, Cu, Mg, Zn, Ti, C, a rare earth composition and Al, rare earth elements are supplemented in the aluminum alloy in the form of an Al-Y-La first intermediate alloy, and C elements are supplemented in the form of an Al-CNT second intermediate alloy, the mechanical strength of the aluminum alloy can be significantly improved while the density of the aluminum alloy is ensured, and the corrosion resistance of the aluminum alloy is effectively improved, in the preparation process of the aluminum alloy, the auxiliary metal is ball milled for multiple times, on the one hand, the contact area of the auxiliary metal and aluminum liquid can be effectively increased, and the smelting difficulty can be reduced, on the other hand, the generation of metal crystals can be effectively promoted in the stirring and smelting process, the homogenization degree and the refinement degree of each element are improved, and then the tensile property and the corrosion resistance of the aluminum alloy are effectively improved, and after the aluminum alloy is combined with acrylic cation to prepare the seamless pipe for oil drilling rods, the service life of the oil drilling rod can be effectively prolonged.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of oil extraction equipment, and particularly relates to an aluminum alloy and a preparation method thereof and a seamless pipe for an oil drilling rod. BACKGROUND

[0002] In the prior art, the oil drilling rod is a key component in the oil drilling process, is used for connecting a drilling machine ground equipment and a drill bit, transmitting torque, conveying drilling fluid, and supporting the weight of the drill bit. In actual oil extraction operation, the drilling rod must be able to withstand huge internal and external pressure, torsion, stretching, bending and vibration.

[0003] In the prior art, the length of the oil drilling rod is generally more than 5000 mm, and the material of the oil drilling rod is generally steel or titanium alloy. The oil drilling rod made of steel has a large self-weight, a high transportation cost, and is not easy to be transported over a long distance. In addition, in the oil extraction operation process, the stress of the oil drilling rod itself is significantly increased, has a high stress corrosion tendency, has a short overall service life, and has a high maintenance cost. The titanium alloy has excellent corrosion resistance and mechanical properties while having a lower density than steel. After the titanium alloy is made into an oil drilling rod, the mechanical property requirement of the drilling rod can be met, and the service life of the drilling rod is greatly prolonged. However, in the prior art, titanium alloy materials are scarce, and the processing and manufacturing cost is extremely high, so it is difficult to mass-produce titanium alloy oil drilling rods. The density of aluminum alloy is significantly lower than that of steel, the raw material cost is low, and it is easy to process. Therefore, there is an urgent need for an aluminum alloy that can combine the advantages of steel and titanium alloy to improve the corrosion resistance and mechanical properties of the oil drilling rod. SUMMARY

[0004] The application is proposed to solve the technical problem in the prior art that the oil drilling rod is a key component in the oil drilling process, the material of the existing oil drilling rod is generally steel or titanium alloy, the steel has a high density, the oil drilling rod made of steel has a high self-weight, poor corrosion resistance, a high transportation cost, and a low service life, and the oil drilling rod has a large scale, and the oil drilling rod made of titanium alloy has an extremely high cost. The application provides an aluminum alloy with high tensile strength, excellent corrosion resistance, and low processing cost, which can replace steel and titanium alloy to be used for manufacturing an oil drilling rod.

[0005] To solve the technical problem proposed in the application, the application further provides a preparation method of the aluminum alloy.

[0006] To solve the technical problem proposed in the application, the application further provides a seamless pipe for an oil drilling rod.

[0007] To solve the technical problem proposed in the application, the application further provides a preparation method of the seamless pipe for the oil drilling rod.

[0008] The application adopts the following scheme, an aluminum alloy, by mass percentage, consisting of the following components: Si 0.72-0.78wt%, Cu 4.3-4.7wt%, Mg 0.5-0.7wt%, Zn 0.13-0.23wt%, Ti 0.025-0.035wt%, C 2.7-3.4wt%, rare earth composition 0.33-0.51wt%, the balance of Al, and unavoidable other impurity elements, the total content of unavoidable other impurity elements being less than or equal to 0.2wt%;

[0009] wherein the rare earth composition is an equal proportion mixed element of Y and La, and the rare earth composition is added in the form of Al-Y-La first intermediate alloy;

[0010] wherein C is added in the form of Al-CNT second intermediate alloy;

[0011] The size specification of CNT is: the diameter range is 50-100nm, and the length range is 20-25μm;

[0012] The density of the aluminum alloy is 3.15-3.52g / cm 3 , and the tensile strength of the aluminum alloy is ≥480Mpa;

[0013] wherein Al is added in the form of aluminum ingot with purity higher than 99% and factory aluminum-containing waste, and the purity of the factory aluminum-containing waste is 30%-45%;

[0014] wherein Si is added in the form of aluminum-silicon alloy, and the aluminum-silicon alloy contains 10%-20% of Si;

[0015] wherein Mg is added in the form of magnesium powder with purity higher than 99%;

[0016] wherein Ti is added in the form of aluminum titanium boron wire, and the aluminum titanium boron wire contains 3-5% of Ti;

[0017] wherein Cu is added in the form of electrolytic copper with purity higher than 99%;

[0018] wherein Zn is added in the form of zinc powder with purity higher than 99%.

[0019] In one of the embodiments, the preparation method of the Al-Y-La first intermediate alloy comprises the following steps:

[0020] Step 101. batching: taking 1 part of aluminum ingot, 8 parts of yttrium powder with an average particle size of 230-350μm, and 8 parts of lanthanum powder with an average particle size of 230-350μm by weight fraction, and after preheating the smelting furnace to 210-330℃, putting all the aluminum ingots into the smelting furnace;

[0021] The yttrium powder and the lanthanum powder are obtained by ball milling. The ball milling method of the yttrium powder and the lanthanum powder comprises the following steps: after the yttrium metal block / lanthanum metal block is preliminarily crushed, the yttrium metal block / lanthanum metal block is transferred to a ball mill, under the condition that the ball-to-material ratio is 1:15, the rare earth metal block is ground to a preset particle size, and then the rare earth metal block is sequentially washed, suction filtered and dried to obtain the rare earth metal powder; and during the ball milling process, the zinc stearate with a mass fraction of 0.5wt% and the silane coupling agent are added drop by drop into the ball mill.

[0022] Step 102. Melting: under an argon atmosphere, the melting temperature is increased at a speed of 100℃ / min, and during the temperature rising process, the molten aluminum is stirred at a speed of 50rpm, and after the temperature is increased to 850℃, the yttrium powder and the lanthanum powder are mixed and pressed into the melting furnace, and then the melting temperature is increased again at a speed of 160℃ / min, and during the temperature rising process, the alloy liquid is stirred at a speed of 220rpm, and after the temperature is increased to 1380℃, the heating is stopped, and a first intermediate alloy liquid is obtained.

[0023] Step 103. Forming: the first intermediate alloy liquid prepared in step 102 is transferred into a forming mold, and under the condition that the vacuum degree is-0.01Mpa and the temperature is 450℃, the first intermediate alloy liquid is kept for 1-3h, and then the temperature is increased to 600℃ and kept for 1-3h, and after natural cooling, an Al-Y-La first intermediate alloy ingot is obtained.

[0024] In the method, by eliminating the internal stress of the first intermediate alloy under low temperature conditions, and then performing temperature rising treatment on the first intermediate alloy, the internal crystal structure of the first intermediate alloy can be formed, the Al-Y-La crystal structure can be prevented from being broken, the production of the network crystal structure can be promoted, and the homogenization degree and stability of the Al-Y-La crystal structure can be improved, so as to facilitate the preparation of the aluminum alloy.

[0025] By compounding Al:Y:La at a mass ratio of 1:8:8 and melting to prepare a first intermediate alloy, on the one hand, the melting difficulty of large-scale production in the later stage can be effectively reduced, and the production energy consumption can be reduced, and on the other hand, by introducing micron-sized rare earth elements into the aluminum alloy, the aluminum alloy crystal can be subjected to secondary dendrites, and a dense network structure can be formed, so that the mechanical properties of the aluminum alloy can be significantly improved while ensuring the low density of the aluminum alloy.

[0026] By compounding rare earth elements to induce the generation of secondary dendrites of the aluminum alloy, and by introducing the CNT nano-gap structure into the aluminum alloy system, an Al-C-X chemical bond can be formed in the aluminum alloy crystal, wherein X is a rare earth element, and then the overall mechanical properties of the aluminum alloy can be significantly improved, and after the aluminum alloy is prepared into a seamless pipe, the dense network structure can significantly improve the mechanical strength of the pipe.

[0027] In one of the embodiments, a preparation method of the Al-CNT second intermediate alloy comprises the following steps:

[0028] Step 201. Blending: the coarse aluminum powder and carbon nanotubes are sequentially put into a ball mill in a mass ratio of 1:3.5, and after ball milling under a ball-to-material ratio of 1:13 to a particle size of 300-420 μm, a pre-sintered binder powder is obtained;

[0029] Step 202. Sintering: the pre-sintered binder powder prepared in step 201 is mixed with sintering salt in a mass ratio of 1:1, and then transferred to a tube furnace, and sintered under vacuum and oxygen-free conditions at a sintering temperature of 700-900℃ for 3-5h to obtain a crude second intermediate alloy;

[0030] Step 203. Impurity removal: the crude second intermediate alloy prepared in step 202 is transferred to deionized water, washed and rinsed, and then dried by suction filtration to obtain an Al-CNT second intermediate alloy.

[0031] In one embodiment, 0.5wt% zinc stearate is added to the coarse aluminum powder and carbon nanotubes during ball milling, and the ball milling process is intermittent, with a stop time of 10-20 min after each ball milling for 30-50 min. Intermittent ball milling can prevent the temperature of the metal powder from being too high, which can damage the internal structure of the CNT and the coarse aluminum powder.

[0032] In one embodiment, the sintering salt in step 202 is a mixed salt obtained by mixing CuCl and ZnCl in a mass ratio of 1:1.

[0033] The second intermediate alloy is prepared by sintering, which can reduce the difficulty of melting in the later large-scale production process and reduce energy consumption. In addition, by selecting CuCl and ZnCl as the sintering salt, the crystal interface bonding degree can be improved, the homogenization degree of the CNT nano-gap structure in the aluminum alloy can be improved, the dispersion strengthening effect of the CNT nano-gap structure in the aluminum alloy crystal can be improved, the crystal stability can be improved, and the mechanical properties of the aluminum alloy can be significantly improved.

[0034] To solve the technical problems provided in the present application, the present application also provides a preparation method of an aluminum alloy, comprising the following steps:

[0035] Step 301: metered magnesium powder, zinc powder, aluminum-silicon alloy, Al-Y-La first intermediate alloy, Al-CNT second intermediate alloy, aluminum titanium boron wire, and electrolytic copper are sequentially put into a pulverizer for pulverization, and then transferred to a ball mill for ball milling to a particle size of 320-450 μm, and then washed and dried to obtain a precursor alloy powder;

[0036] Step 302: Under a helium atmosphere, the weighed aluminum ingots are all put into a smelting furnace, and the smelting furnace is heated to 235-310℃. During the heating process, the aluminum ingots are stirred at 360 rpm. When the smelting furnace is heated to 830-850℃ at a heating rate of 130℃ / min, the precursor alloy powder prepared in step 301 is pressed into the smelting furnace. During the heating process, the aluminum alloy melt is stirred at 250 rpm. After the aluminum alloy melt is completely melted, the aluminum alloy liquid is obtained.

[0037] Step 303: Under a helium atmosphere, the aluminum alloy liquid prepared in step 302 is poured and cast into a static furnace. After being kept at 730-750℃ for 3-5h, the aluminum alloy liquid is poured into a refining agent with a model of LM15F. The refining is performed twice, and the single refining time lasts for 25-30min. After each refining, the aluminum alloy liquid is kept for 30-40min. After the refining is completed, the refined aluminum alloy liquid is obtained.

[0038] Step 304: The refined aluminum alloy liquid prepared in step 303 is sequentially flowed through a pyrotek SNIF double-rotor degassing box and a double-stage plate filter box with a porosity of 40ppi / 80ppi, and then transferred to a casting mold. After casting and annealing in an annealing furnace, the aluminum alloy rod is obtained.

[0039] The specification of the casting mold is φ229mm. The refined aluminum alloy liquid flows out of the furnace port at a temperature of 745-765℃. After cooling and solidification, the aluminum alloy cast rod is obtained. The aluminum alloy cast rod is stacked and then transferred to a homogenization annealing furnace for annealing. After annealing, the aluminum alloy rod is obtained.

[0040] The annealing process includes primary annealing and secondary annealing. The primary annealing temperature is 390℃, and the primary annealing time is 8h. The secondary annealing temperature is 495℃, and the secondary annealing time is 10h.

[0041] In one embodiment, before the aluminum alloy liquid is refined in step 303, a sample is taken and analyzed by a spectral analyzer to analyze the composition of the aluminum alloy liquid. When the weight percentage of each element is within the preset standard range, the refining is performed. When the weight percentage of each element is outside the preset standard range, any one or more combinations of aluminum ingots, magnesium powder, zinc powder, aluminum-silicon alloy, Al-Y-La first intermediate alloy, Al-CNT second intermediate alloy, aluminum titanium boron wire, and electrolytic copper are added to the aluminum alloy liquid until the weight percentage of each element in the aluminum alloy liquid is within the preset standard range.

[0042] To solve the technical problems proposed in the present application, the present application further provides a seamless pipe for oil drilling rod, comprising a pipe body and a corrosion-resistant layer coated on the inner and outer circumferences of the pipe body simultaneously, wherein the pipe body is made of the aluminum alloy described above, and the corrosion-resistant layer is made of acrylic cationic emulsion.

[0043] The preparation method of the pipe body comprises the following steps: transferring the aluminum alloy rod prepared in step 304 to a heating furnace, heating the aluminum alloy rod to 490-510 DEG C, and then transferring it to an extruder to be reversely extruded into a seamless pipe semi-product, and then tension-straightening into a seamless pipe semi-product for oil drilling rod with a specified outer diameter, and then standing for 72 hours, and then making one end of the seamless pipe semi-product into a tapered pipe, and then drawing through a pipe drawing die to obtain a drawn pipe semi-product, and then straightening, deoiling and heat treating the drawn pipe semi-product to obtain the pipe body.

[0044] In one of the embodiments, the temperature of the heat treatment is 160 DEG C, and the time of the heat treatment is 18 hours.

[0045] In one of the embodiments, when the pipe body is cooled to 30 DEG C-42 DEG C, it is immersed in acrylic cationic emulsion, the soaking time is 20-30 seconds, and after the soaking is completed, the pipe body is obtained after drying and polishing.

[0046] In one of the embodiments, a spray gun can also be used to spray the acrylic cationic emulsion on the outer circumference of the pipe body.

[0047] In one of the embodiments, the acrylic cationic emulsion is composed of the following components in parts by weight: 35-55 parts of methyl methacrylate, 8-12 parts of ethyl acrylate, 12-25 parts of functional monomer aqueous solution, 5-10 parts of emulsifier, 8-15 parts of initiator, and the balance of water; wherein the functional monomer aqueous solution is a water solution compounded from polymerizable polyhydroxy organic amine monomer and N-hydroxyethyl acrylamide at a mass ratio of 4:1.5; wherein the emulsifier is cetyltrimethylammonium bromide; and the initiator is V50.

[0048] In one of the embodiments, the preparation method of the acrylic cationic emulsion comprises the following steps:

[0049] Step 401. After methyl methacrylate and ethyl acrylate are dispersed in a dispersant, the mixture is transferred to a reaction kettle, and after stirring and activating at 60-75 DEG C water bath and 1000 rpm for 10 minutes, an activated resin mixture is obtained.

[0050] Step 402. The activated resin mixture prepared in step 401 is sequentially added with a functional monomer aqueous solution, an emulsifier, an initiator and water, and then reacted under a helium atmosphere, -0.05Mpa, 90-100℃, 1600rpm for 1-2h to obtain the acrylic cationic emulsion.

[0051] By coating the acrylic cationic emulsion on the aluminum alloy seamless pipe material cooled to 30-42℃ after the completion of heat treatment, the adhesion of the corrosion-resistant layer can be effectively improved. On the one hand, there are internal nanopore structures in the CNT inside the aluminum alloy crystal, and the corrosion-resistant layer will be crosslinked in the pore structure during the crosslinking process, thereby significantly improving the adhesion of the corrosion-resistant layer. On the other hand, the hydroxyl-rich acrylic emulsion is selected as the corrosion-resistant coating, and the CNT in the void structure will form a C-OH bond with the emulsion, thereby significantly improving the adhesion and the service life of the corrosion-resistant layer.

[0052] Compared with the prior art, the present application has the following beneficial effects:

[0053] The present application provides an aluminum alloy and a preparation method thereof and a seamless pipe material for oil drilling rods, wherein the aluminum alloy is composed of Si, Cu, Mg, Zn, Ti, C, rare earth composition and Al. By adding rare earth elements in the form of Al-Y-La first intermediate alloy and C elements in the form of Al-CNT second intermediate alloy into the aluminum alloy, the mechanical strength of the aluminum alloy can be significantly improved while ensuring the density of the aluminum alloy, and the corrosion resistance of the aluminum alloy can be effectively improved. In the preparation process of the aluminum alloy, the auxiliary metal is ball milled for multiple times, which can effectively increase the contact area between the auxiliary metal and the aluminum liquid, reduce the smelting difficulty, and effectively promote the generation of metal crystals during stirring and smelting, thereby improving the homogenization degree and refinement degree of each element, and effectively improving the tensile properties and corrosion resistance of the aluminum alloy. After the aluminum alloy is combined with the acrylic cationic emulsion to prepare the seamless pipe material for oil drilling rods, the service life of the oil drilling rod can be effectively prolonged. BRIEF DESCRIPTION OF DRAWINGS

[0054] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced as follows.

[0055] Figure 1 is the tensile strength test diagram of the metal sample in the present application examples 1-3 and comparative examples 1, 2, 4, 5

[0056] Figure 2 is the crystal phase diagram of the aluminum alloy prepared in the present application example 3;

[0057] Figure 3 is the crystal phase diagram of the aluminum alloy prepared in the present application comparative example 1;

[0058] Figure 4 is a crystal phase diagram of the aluminum alloy prepared in Example 2 of the present application;

[0059] Figure 5 is an adhesion test diagram of the No. 1 test piece in Test 5 of the present application after 120 h salt spray test;

[0060] Figure 6 is a corrosion protection layer diagram of the No. 1 test piece in Test 5 of the present application after 120 h salt spray test. DETAILED DESCRIPTION

[0061] In combination with Figures 1-6 and Examples 1-3 and Comparative Examples 1-5 below, the technical solution is further illustrated.

[0062] Example 1

[0063] (1) Preparation of the Al-Y-La first intermediate alloy, comprising the following steps:

[0064] Step 101. Batching: take 1 part of aluminum ingot, 8 parts of yttrium powder with an average particle size of 342 μm, and 8 parts of lanthanum powder with an average particle size of 337 μm by weight fraction, preheat the smelting furnace to 326℃, and then press all the aluminum ingots into the smelting furnace under an argon atmosphere;

[0065] Step 102. Smelting: under an argon atmosphere, increase the smelting temperature at a rate of 100℃ / min, and stir the molten aluminum at 50 rpm during the heating process. After the temperature is increased to 850℃, press the mixed yttrium and lanthanum powders into the smelting furnace, and then increase the smelting temperature again at a rate of 160℃ / min. Stir the alloy liquid at 220 rpm during the heating process. Stop heating after the temperature is increased to 1380℃, and then the first intermediate alloy liquid is obtained after the metal is completely melted;

[0066] Step 103. Forming: transfer the first intermediate alloy liquid prepared in step 102 into a forming mold, and then heat it at a vacuum degree of -0.01 Mpa and a temperature of 450℃ for 2.6 h. After the temperature is increased to 600℃, heat it again for 2.5 h, and then naturally cool it to obtain the Al-Y-La first intermediate alloy ingot.

[0067] (2) Preparation of the Al-CNT second intermediate alloy, comprising the following steps:

[0068] Step 201. Batching: sequentially put the coarse aluminum powder and carbon nanotubes into a ball mill at a mass ratio of 1:3.5, and then ball mill them under a ball-to-material ratio of 1:13 until the average particle size is 416 μm. After washing, suction filtration, and drying, the pre-sintered alloy powder is obtained;

[0069] The ball milling process is intermittent ball milling, and the machine is stopped for 18 min after each ball milling for 45 min.

[0070] Step 202. Sintering: the pre-sintered alloy powder prepared in step 201 is mixed with sintering salt at a mass ratio of 1:1, then transferred to a tube furnace, sintered at a sintering temperature of 882℃ under vacuum and oxygen-free conditions for 4.8h, to obtain a crude second intermediate alloy;

[0071] wherein the sintering salt is a mixed salt obtained by mixing CuCl and ZnCl at a mass ratio of 1:1;

[0072] Step 203. Impurity removal: the crude second intermediate alloy prepared in step 202 is transferred to deionized water, washed and rinsed thoroughly, and then filtered and dried by suction, to obtain an Al-CNT second intermediate alloy.

[0073] (3) Preparation of an aluminum alloy, comprising the following steps:

[0074] Step 301: according to the composition table shown in Table 1, the weighed magnesium powder, zinc powder, aluminum-silicon alloy, Al-Y-La first intermediate alloy, Al-CNT second intermediate alloy, aluminum titanium boron wire, and electrolytic copper are sequentially fed into a pulverizer for pulverization, then transferred to a ball mill for ball milling until the average particle size is 435μm, and then washed and dried to obtain a precursor alloy powder;

[0075] Step 302: under a helium atmosphere, according to the composition table shown in Table 1, the weighed aluminum ingot is fed into a smelting furnace, and the smelting furnace is heated to 310℃. During the heating process, the aluminum ingot is stirred at 360rpm. When the smelting furnace is heated to 850℃ at a heating rate of 130℃ / min, the precursor alloy powder prepared in step 301 is pressed into the smelting furnace. During the heating process, the aluminum alloy melt is stirred at 250rpm. After the aluminum alloy melt is completely melted, an aluminum alloy liquid is obtained.

[0076] Step 303: under a helium atmosphere, the aluminum alloy liquid prepared in step 302 is poured and cast into a stationary furnace, and the aluminum alloy liquid is heated to 750℃ and held for 5h. Then, a refining agent is added to the aluminum alloy liquid, and the refining is performed twice, with a single refining time of 30min. After each refining, the aluminum alloy liquid is allowed to stand for 40min. After the refining is completed, a refined aluminum alloy liquid is obtained.

[0077] wherein, before refining the aluminum alloy liquid, a sample is taken and analyzed by a spectral analyzer to determine the composition of the aluminum alloy liquid. When the weight percentage of each element is within the preset standard range, the refining is performed. When the weight percentage of each element is outside the preset standard range, any one or a combination of more than one of the following is added to the aluminum alloy liquid: aluminum ingot, magnesium powder, zinc powder, aluminum-silicon alloy, Al-Y-La first intermediate alloy, Al-CNT second intermediate alloy, aluminum titanium boron wire, and electrolytic copper, until the weight percentage of each element in the aluminum alloy liquid is within the preset standard range.

[0078] Step 304: The refined aluminum alloy liquid prepared in step 303 flows through the double-rotor degassing box and the double-stage plate filter box in turn and reaches the casting mold. After casting and annealing in the annealing furnace, an aluminum alloy rod is obtained.

[0079] (4) Preparation of an aluminum alloy seamless pipe for oil drilling rods

[0080] The seamless pipe for oil drilling rods comprises a pipe body and a corrosion-resistant coating simultaneously coated on the inner and outer circumferences of the pipe body. The pipe body is made of the aluminum alloy described above, and the corrosion-resistant coating is made of an acrylic cationic emulsion.

[0081] The preparation method of the pipe body comprises the following steps: transferring the aluminum alloy rod prepared in step 304 to a heating furnace, heating the aluminum alloy rod to 510℃, transferring the aluminum alloy rod to an extruder for reverse extrusion into a seamless pipe semi-product, tension-straightening the seamless pipe semi-product into a seamless pipe semi-product for oil drilling rods with a specified outer diameter, and standing for 72h. Then, one end of the seamless pipe semi-product is made into a tapered pipe, and the tapered pipe is drawn into a drawn pipe semi-product through a drawn pipe mold. After straightening, oil removal, and heat treatment, the pipe body is obtained.

[0082] The temperature of the heat treatment is 160℃, and the time of the heat treatment is 18h.

[0083] After the pipe body is cooled to 40.5℃, it is immersed in the acrylic cationic emulsion for 28s. After drying and polishing, the seamless pipe for oil drilling rods is obtained.

[0084] (5) Preparation of an acrylic cationic emulsion, comprising the following steps:

[0085] Step 401: According to the ingredient table in Table 2, methyl methacrylate and ethyl acrylate are sequentially added to a dispersant for dispersion, and the mixture is transferred to a reaction kettle. After stirring and activation at 73℃ water bath and 1000rpm for 10min, an activated resin mixture is obtained.

[0086] Step 402: To the activated resin mixture prepared in step 401, functional monomer aqueous solution, emulsifier, initiator, and water are sequentially added. After reaction under helium atmosphere, -0.05Mpa, water bath 98℃, 1600rpm for 1-2h, an acrylic cationic emulsion is obtained.

[0087] Example 2

[0088] (1) Preparation of Al-Y-La first intermediate alloy, comprising the following steps:

[0089] Step 101. Batching: take 1 part of aluminum ingot, 8 parts of yttrium powder with an average particle size of 284 μm, and 8 parts of lanthanum powder with an average particle size of 277 μm by weight fraction, preheat the smelting furnace to 295℃, and then press all the aluminum ingots into the smelting furnace under an argon atmosphere;

[0090] Step 102. Smelting: under an argon atmosphere, increase the smelting temperature at a rate of 100℃ / min, stir the molten aluminum at 50 rpm during the heating process, press the mixed yttrium powder and lanthanum powder into the smelting furnace after heating to 850℃, increase the smelting temperature again at a rate of 160℃ / min, stir the alloy liquid at 220 rpm during the heating process, stop heating after heating to 1380℃, and the first intermediate alloy liquid is obtained after the metal is completely melted;

[0091] Step 103. Forming: transfer the first intermediate alloy liquid prepared in step 102 into a forming mold, heat at a vacuum degree of -0.01 Mpa and a temperature of 450℃ for 2h, then heat to 600℃ for 2.2h, and the Al-Y-La first intermediate alloy ingot is obtained after natural cooling.

[0092] (2) Preparation of Al-CNT second intermediate alloy, comprising the following steps:

[0093] Step 201. Batching: sequentially add coarse aluminum powder and carbon nanotubes into a ball mill at a mass ratio of 1:3.5, ball mill to an average particle size of 383 μm under a ball-to-material ratio of 1:13, then wash, filter, and dry to obtain a pre-sintered alloy powder;

[0094] The ball milling process is intermittent, and the machine is stopped for 15 min after each 40 min of ball milling;

[0095] Step 202. Sintering: mix the pre-sintered alloy powder prepared in step 201 with sintering salt at a mass ratio of 1:1, then transfer into a tube furnace, and sinter for 4.2h under vacuum and oxygen-free conditions at a sintering temperature of 835℃ to obtain a crude second intermediate alloy;

[0096] The sintering salt is a mixed salt obtained by mixing CuCl and ZnCl at a mass ratio of 1:1;

[0097] Step 203. Impurity removal: transfer the crude second intermediate alloy prepared in step 202 into deionized water, wash thoroughly, filter, and dry to obtain the Al-CNT second intermediate alloy.

[0098] (3) Preparation of aluminum alloy, comprising the following steps:

[0099] Step 301: According to the composition table shown in Table 1, the measured magnesium powder, zinc powder, aluminum-silicon alloy, Al-Y-La first intermediate alloy, Al-CNT second intermediate alloy, aluminum-titanium-boron wire and electrolytic copper are sequentially put into a pulverizer for pulverization, then transferred to a ball mill for ball milling until the average particle size is 400μm, and then washed and dried to obtain the precursor alloy powder.

[0100] Step 302: Under a helium atmosphere, according to the composition table shown in Table 1, all the measured aluminum ingots are put into the melting furnace, and the melting furnace is heated to 275°C. During the heating process, the aluminum ingots are stirred at 360 rpm. The melting furnace is then heated to 842°C at a heating rate of 130°C / min. During the heating process, the precursor alloy powder prepared in step 301 is injected into the melting furnace. During the heating process, the aluminum alloy melt is stirred at 250 rpm. After the aluminum alloy melt is completely melted, the aluminum alloy liquid is obtained.

[0101] Step 303: Under a helium atmosphere, the aluminum alloy liquid prepared in step 302 is tilted and poured into a settling furnace. After holding at 740°C for 4 hours, a refining agent is added to the aluminum alloy liquid. The refining is carried out twice, with each refining lasting 27 minutes. After each refining, the aluminum alloy liquid is settling for 35 minutes. After the refining is completed, the refined aluminum alloy liquid is obtained.

[0102] Before refining the aluminum alloy liquid, samples are taken and analyzed using a spectrometer. When the weight percentage of each element is within the preset standard range, refining is carried out. When the weight percentage of each element is outside the preset standard range, one or more of the following are added to the aluminum alloy liquid: aluminum ingots, magnesium powder, zinc powder, aluminum-silicon alloy, Al-Y-La first intermediate alloy, Al-CNT second intermediate alloy, aluminum-titanium-boron wire, and electrolytic copper, until the weight percentage of each element in the aluminum alloy liquid is within the preset standard range.

[0103] Step 304: The refined aluminum alloy liquid prepared in step 303 flows sequentially through a dual-rotor degassing box and a dual-stage plate filter box before reaching the casting mold. After casting is completed and annealed in an annealing furnace, aluminum alloy rods are obtained.

[0104] (4) Preparation of seamless aluminum alloy tubing for oil drilling pipes

[0105] Seamless tubing for oil drilling pipe, comprising a tubing body and an anti-corrosion coating applied to both the inner and outer circumferences of the tubing body, wherein the tubing body is made of the aforementioned aluminum alloy and the anti-corrosion coating is made of cationic acrylic emulsion.

[0106] The preparation method of the pipe body comprises the following steps: transferring the aluminum alloy rod prepared in step 304 to a heating furnace, heating the aluminum alloy rod to 500 DEG C, and then transferring to an extruder to reversely extrude a seamless pipe semi-product, and then tension straightening to a seamless pipe semi-product with a specified outer diameter for oil drilling rods, and then standing for 72 h, and then making one end of the seamless pipe semi-product into a tapered pipe, and then drawing through a pipe drawing die to obtain a drawn pipe semi-product, and then straightening, oil removal and heat treatment to obtain the pipe body.

[0107] The heat treatment temperature is 160 DEG C, and the heat treatment time is 18 h.

[0108] The pipe body is immersed in the acrylic cationic emulsion after being cooled to 37 DEG C, the soaking time is 25 s, and the oil drilling rod seamless pipe is obtained after drying and polishing.

[0109] The preparation of the acrylic cationic emulsion comprises the following steps:

[0110] Step 401. According to the ingredient table shown in Table 2, methyl methacrylate and ethyl acrylate are sequentially added to the dispersant for dispersion, and then the mixture is transferred to a reaction kettle, stirred and activated at 70 DEG C water bath and 1000 rpm for 10 min, and then an activated resin mixture is obtained.

[0111] Step 402. The activated resin mixture prepared in step 401 is sequentially added with a functional monomer aqueous solution, an emulsifier, an initiator and water, and then reacted under helium atmosphere at-0.05 Mpa, 96 DEG C and 1600 rpm for 1-2 h to obtain an acrylic cationic emulsion.

[0112] Example 3

[0113] The preparation of the Al-Y-La first intermediate alloy comprises the following steps:

[0114] Step 101. Batching: according to the weight fraction, 1 part of aluminum ingot, 8 parts of yttrium powder with an average particle size of 235 μm and 8 parts of lanthanum powder with an average particle size of 239 μm are taken, and the smelting furnace is preheated to 220 DEG C, and then all the aluminum ingots are pressed into the smelting furnace under argon atmosphere;

[0115] Step 102. Melting: under argon atmosphere, the melting temperature is raised at a speed of 100 DEG C / min, and the molten aluminum is stirred at 50 rpm during the heating process, the yttrium powder and lanthanum powder are mixed and pressed into the smelting furnace after the temperature is raised to 850 DEG C, the melting temperature is raised again at a speed of 160 DEG C / min, and the alloy liquid is stirred at 220 rpm during the heating process, and the heating is stopped after the temperature is raised to 1380 DEG C to obtain the first intermediate alloy liquid.

[0116] Step 103. Forming: the first intermediate alloy liquid prepared in step 102 is transferred into a forming mold, and is kept at a vacuum degree of -0.01 Mpa and a temperature of 450℃ for 1.5 h, and then is kept at a temperature of 600℃ for 1 h, and is naturally cooled to obtain an Al-Y-La first intermediate alloy ingot.

[0117] (2) Preparation of the Al-CNT second intermediate alloy, comprising the following steps:

[0118] Step 201. Blending: coarse aluminum powder and carbon nanotubes are sequentially put into a ball mill in a mass ratio of 1:3.5, and are ball milled to an average particle size of 330 μm under a ball-to-material ratio of 1:13, and then are washed, filtered, and dried to obtain a pre-sintered alloy powder;

[0119] The ball milling process is intermittent ball milling, and the ball mill is stopped for 10 min after each ball milling for 30 min.

[0120] Step 202. Sintering: the pre-sintered alloy powder prepared in step 201 is mixed with sintering salt in a mass ratio of 1:1, and then is transferred into a tube furnace, and is sintered under a vacuum and oxygen-free condition at a sintering temperature of 730℃ for 3.5 h to obtain a crude second intermediate alloy.

[0121] The sintering salt is a mixed salt obtained by mixing CuCl and ZnCl in a mass ratio of 1:1.

[0122] Step 203. Impurity removal: the crude second intermediate alloy prepared in step 202 is transferred into deionized water, and is washed and rinsed, and then is filtered and dried to obtain an Al-CNT second intermediate alloy.

[0123] (3) Preparation of the aluminum alloy, comprising the following steps:

[0124] Step 301: according to the ingredient table shown in Table 1, metered magnesium powder, zinc powder, aluminum-silicon alloy, Al-Y-La first intermediate alloy, Al-CNT second intermediate alloy, aluminum titanium boron wire, and electrolytic copper are sequentially put into a pulverizer, and are pulverized, and then are transferred into a ball mill, and are ball milled to an average particle size of 325 μm, and then are washed and dried to obtain a precursor alloy powder;

[0125] Step 302: under a helium atmosphere, according to the ingredient table shown in Table 1, metered aluminum ingots are all put into a melting furnace, and the melting furnace is heated to 247℃, and in the heating process, the aluminum ingots are stirred at 360 rpm, and the melting furnace is heated to 832℃ at a heating rate of 130℃ / min, and in the heating process, the precursor alloy powder prepared in step 301 is pressed into the melting furnace, and in the heating process, the aluminum alloy melt is stirred at 250 rpm, and after the aluminum alloy melt is completely melted, an aluminum alloy liquid is obtained.

[0126] Step 303: The aluminum alloy liquid prepared in step 302 is poured into a holding furnace under a helium atmosphere. After holding at 733℃ for 3h, a refining agent is added to the aluminum alloy liquid. The refining is performed twice, with each single refining lasting for 25min. After each refining, the aluminum alloy liquid is held for 30min. After the refining is completed, the refined aluminum alloy liquid is obtained.

[0127] Before the refining of the aluminum alloy liquid, the composition of the aluminum alloy liquid is analyzed by a spectrum analyzer. When the weight percentage of each element is within the preset standard range, the refining is performed. When the weight percentage of each element is outside the preset standard range, any one or more than one combination of the following is added to the aluminum alloy liquid: aluminum ingot, magnesium powder, zinc powder, aluminum-silicon alloy, Al-Y-La first intermediate alloy, Al-CNT second intermediate alloy, aluminum-titanium-boron wire, and electrolytic copper, until the weight percentage of each element in the aluminum alloy liquid is within the preset standard range.

[0128] Step 304: The refined aluminum alloy liquid prepared in step 303 flows through a double-rotor degassing box and a double-stage plate filter box in sequence, and then reaches a casting mold. After casting and annealing in an annealing furnace, the aluminum alloy rod is obtained.

[0129] (4) Preparation of an aluminum alloy seamless pipe for oil drilling rods

[0130] The seamless pipe for oil drilling rods comprises a pipe body and a corrosion-resistant layer simultaneously coated on the inner and outer peripheries of the pipe body. The pipe body is made of the above-mentioned aluminum alloy, and the corrosion-resistant layer is made of an acrylic cationic emulsion.

[0131] The preparation method of the pipe body comprises the following steps: transferring the aluminum alloy rod prepared in step 304 to a heating furnace, heating the aluminum alloy rod to 495℃, transferring the aluminum alloy rod to an extruder for reverse extrusion into a seamless pipe semi-product, tension-straightening the seamless pipe semi-product into a seamless pipe semi-product for oil drilling rods with a specified outer diameter, and standing for 72h. One end of the seamless pipe semi-product is made into a tapered pipe, and the tapered pipe semi-product is drawn through a pipe drawing die to obtain a drawn pipe semi-product. The drawn pipe semi-product is straightened, deoiled, and heat-treated to obtain the pipe body.

[0132] The heat treatment is performed at a temperature of 160℃ for 18h.

[0133] After the pipe body is cooled to 32℃, it is immersed in the acrylic cationic emulsion for 22s. After soaking, the pipe body is dried and polished to obtain the seamless pipe for oil drilling rods.

[0134] (5) Preparation of an acrylic cationic emulsion, comprising the following steps:

[0135] Step 401. According to the ingredient table shown in Table 2, methyl methacrylate and ethyl acrylate were sequentially added into the dispersant and uniformly dispersed, and then the mixture was transferred into a reaction kettle. After stirring and activating at 63°C water bath and 1000 rpm for 10 min, an activated resin mixture was obtained.

[0136] Step 402. The activated resin mixture prepared in step 401 was sequentially added with functional monomer aqueous solution, emulsifier, initiator and water. After reaction at -0.05 Mpa, 93°C and 1600 rpm for 1.2 h under helium atmosphere, an acrylic cationic emulsion was obtained.

[0137] Comparative Example 1

[0138] The rare earth elements in Example 3 were removed, i.e. the first intermediate alloy was removed in the preparation process of the aluminum alloy, and the content of the rare earth elements was supplemented with Al. The composition and process remained unchanged.

[0139] Comparative Example 2

[0140] The C element in Example 3 was removed, i.e. the second intermediate alloy was removed in the preparation process of the aluminum alloy, and the content of the C element was supplemented with Al. The composition and process remained unchanged.

[0141] Comparative Example 3

[0142] Pure aluminum with a purity of 99%.

[0143] Comparative Example 4

[0144] TC10 titanium alloy.

[0145] Comparative Example 5

[0146] Steel oil pipe material specified in GB9948-88.

[0147] Table 1 Aluminum alloy composition table of Examples 1-3 and Comparative Examples 1-2

[0148]

[0149] Table 2 Composition table of acrylic cationic emulsion of Examples 1-3

[0150] Component (parts by mass) Example 1 Example 2 Example 3 Methyl methacrylate 35.4 43.7 53.7 Ethyl acrylate 9.1 11.3 11.9 Functional monomer aqueous solution 13.5 18.7 23.4 Emulsifier 6.2 7.8 9.4 Initiator 8.6 12.7 14.6 Water Balance Balance Balance

[0151] The aluminum alloys and pipes prepared from Examples 1-3 and Comparative Examples 1-2, and the materials involved in Comparative Examples 3-5 were tested as follows:

[0152] Test 1. Density test: equal amounts of metal samples were taken and their densities were tested respectively.

[0153] Test 2. Strength test: after the specified metal sample was prepared according to GB / T 228.1-2021 standard, its tensile strength was tested respectively;

[0154] Test 3. Anti-corrosion performance test: after the specified metal sample was prepared according to GB / T 20121-2006 standard, salt spray test was carried out respectively, wherein two groups of test objects were additionally tested, one of which, the aluminum alloy prepared in Example 3 was made into a test piece, and after the surface of the test piece was coated with an acrylic cationic emulsion, salt spray test was carried out, and the other, the seamless pipe with a diameter of 79 mm prepared in Example 3 was cut into a test piece with a thickness of 3 cm, and then salt spray test was carried out; the test results are shown in Table 3 below.

[0155] Table 3 Test results of Examples and Comparative Examples 1-3 in tests 1-3

[0156]

[0157] In order to further explore the anti-corrosion performance of the seamless pipe for petroleum drill pipe and the influence of the anti-corrosion layer on the anti-corrosion performance of the pipe, further test 4 was carried out: the aluminum alloy prepared in Example 3, Comparative Example 1, Comparative Example 2 and the petroleum pipe in Comparative Example 5 were made into test plates according to GB / T 20121-2006, and then the anti-corrosion layer prepared in Example 3 was applied on them, respectively, to obtain test pieces 1-4; the seamless pipe with a diameter of 79 mm prepared in Example 3 was cut into a short pipe with a thickness of 3 cm to obtain test piece 5.

[0158] In order to further explore the influence of the anti-corrosion layer on the anti-corrosion performance of the pipe, further test 5 was carried out: the adhesion test of the test plates after salt spray test was carried out according to GB / T 9286-1998 standard, and the test results are shown in Table 4 below.

[0159] Table 4 Test results of test pieces 1-5 in tests 4 and 5

[0160]

[0161]

[0162] In combination Figures 1-6 As can be seen from Tables 3-4,

[0163] In Comparative Example 1, the rare earth elements in Example 3 were removed, i.e. the first intermediate alloy was removed during the preparation of the aluminum alloy, and the content of the rare earth elements was supplemented with Al, and the composition and process remained unchanged, such as Figure 2As shown, the aluminum alloy crystal phase diagram prepared in Example 3 is rich in Al-C-X network structure, wherein X is a rare earth element, and the secondary dendrite of the aluminum alloy is induced by compounding the rare earth element, and the CNT nano-gap structure is introduced into the aluminum alloy system, the Al-C-X chemical bond is formed inside the aluminum alloy crystal, and the mechanical properties of the aluminum alloy are significantly improved. After the seamless pipe is prepared, the dense network structure can significantly improve the mechanical strength of the pipe, such as Figure 3 As shown, after the rare earth element is removed, the aluminum alloy cannot form secondary dendrites, and the binding force with CNT is small, so that the dense internal structure cannot be formed, and the mechanical properties and corrosion resistance are significantly reduced;

[0164] In Comparative Example 2, the C element in Example 3 is removed, that is, the second intermediate alloy is removed during the preparation of the aluminum alloy, and the content of the C element is supplemented with Al, and the composition and process remain unchanged, as shown in Figure 4 As shown, the secondary dendrite of the aluminum alloy is induced by introducing the rare earth element, and the network structure inside the crystal phase increases, but after the CNT is introduced, the Al-C-X chemical bond cannot be formed inside the crystal, the scale of the network structure is small, and the mechanical properties and corrosion resistance are correspondingly reduced;

[0165] As shown in Figures 5-6 As shown, after 120h salt spray test, the corrosion layer of No. 1 test piece still has 0 level adhesion, and there is no obvious peeling trace on the test piece. In actual implementation process, in seawater use scene, the service life can be much higher than that of salt spray test. By coating the acrylic cationic emulsion on the aluminum alloy seamless pipe cooled to 30-42℃ after heat treatment, the adhesion of the corrosion layer can be effectively improved. On the one hand, there are CNT internal nano-pore structures inside the aluminum alloy crystal, and the corrosion layer will be crosslinked in the pore structure during crosslinking, thereby significantly improving the adhesion of the corrosion layer. On the other hand, the hydroxyl-rich acrylic emulsion is selected as the corrosion coating, and the C-OH bond is formed between the CNT in the gap structure and the emulsion, thereby significantly improving the adhesion and the service life of the corrosion layer.

[0166] The above is only an embodiment of the present application, and does not limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An aluminum alloy, characterized in that, By mass percentage, it consists of the following components: Si 0.72-0.78wt%, Cu 4.3-4.7wt%, Mg 0.5-0.7wt%, Zn 0.13-0.23wt%, Ti 0.025-0.035wt%, C 2.7-3.4wt%, rare earth composition 0.33-0.51wt%, balance Al, and other unavoidable impurity elements, the total content of which is less than or equal to 0.2wt%. The rare earth composition is a mixture of Y and La in equal proportions, and the rare earth composition is added in the form of Al-Y-La first intermediate alloy. C is added in the form of an Al-CNT second intermediate alloy; The density of the aluminum alloy is 3.15-3.52 g / cm³. 3 The tensile strength of the aluminum alloy is ≥480 MPa.

2. The aluminum alloy according to claim 1, characterized in that, The preparation method of the Al-Y-La first intermediate alloy includes the following steps: Step 101. Ingredients: By weight, take 1 part aluminum ingot, 8 parts yttrium powder, and 8 parts lanthanum powder. After preheating the melting furnace to 210-330℃, put all the aluminum ingots into the melting furnace. Step 102. Melting: Under an argon atmosphere, increase the melting temperature at a rate of 100℃ / min. During the heating process, stir the molten aluminum at 50 rpm. After heating to 850℃, mix yttrium powder and lanthanum powder and press them into the melting furnace. Increase the melting temperature again at a rate of 160℃ / min. During the heating process, stir the alloy liquid at 220 rpm. After heating to 1380℃, stop heating to obtain the first intermediate alloy liquid. Step 103. Molding: The first intermediate alloy liquid prepared in step 102 is transferred to a molding die and kept at 450°C under a vacuum of -0.01 MPa for 1-3 hours. Then, the temperature is raised to 600°C and kept at 600°C for 1-3 hours. After natural cooling, the Al-Y-La first intermediate alloy ingot is obtained.

3. An aluminum alloy according to claim 1, characterized in that, The preparation method of the Al-CNT second intermediate alloy includes the following steps: Step 201. Ingredients: Add coarse aluminum powder and carbon nanotubes into a ball mill at a mass ratio of 1:3.

5. Under the condition of ball-to-material ratio of 1:13, ball mill them until the particle size is 300-420μm. After washing, filtration and drying, the pre-sintered gold powder is obtained. Step 202. Sintering: The pre-sintered gold powder prepared in step 201 is mixed with sintering salt at a mass ratio of 1:1 and then transferred to a tube furnace. After sintering for 3-5 hours under vacuum and oxygen-free conditions and a sintering temperature of 700-900℃, the crude second intermediate alloy is obtained. Step 203. Impurity removal: The crude second intermediate alloy prepared in step 202 is transferred to deionized water, and after washing, filtration and drying, Al-CNT second intermediate alloy is obtained.

4. An aluminum alloy according to claim 3, characterized in that, In step 201, 0.5 wt% zinc stearate is added to the coarse aluminum powder and carbon nanotubes during ball milling. The ball milling process is intermittent, with a 10-20 minute break after each 30-50 minute milling.

5. An aluminum alloy according to claim 3, characterized in that, In step 202, the sintering salt is a mixed salt obtained by mixing CuCl and ZnCl in a mass ratio of 1:

1.

6. A method for preparing an aluminum alloy, used to prepare the aluminum alloy according to any one of claims 1-5, characterized in that, Includes the following steps: Step 301: The measured magnesium powder, zinc powder, aluminum-silicon alloy, Al-Y-La first intermediate alloy, Al-CNT second intermediate alloy, aluminum-titanium-boron wire and electrolytic copper are sequentially fed into a pulverizer and pulverized. Then, they are transferred to a ball mill and ball-milled to 320-450μm. After washing and drying, the precursor alloy powder is obtained. Step 302: Under a helium atmosphere, all the measured aluminum ingots are put into the melting furnace and the melting furnace is heated to 235-310℃. During the heating process, the aluminum ingots are stirred at 360 rpm. Then the melting furnace is heated to 830-850℃ at a heating rate of 130℃ / min. During the heating process, the precursor alloy powder prepared in step 301 is injected into the melting furnace and the aluminum alloy melt is stirred at 250 rpm. After the aluminum alloy melt is completely melted, the aluminum alloy liquid is obtained. Step 303: Under a helium atmosphere, the aluminum alloy liquid prepared in step 302 is tilted and poured into a settling furnace. After holding at 730-750℃ for 3-5 hours, a refining agent is added to the aluminum alloy liquid. The refining is performed twice, with each refining lasting 25-30 minutes. After each refining, the aluminum alloy liquid is settling for 30-40 minutes. After the refining is completed, the refined aluminum alloy liquid is obtained. Step 304: The refined aluminum alloy liquid prepared in step 303 is sequentially passed through a dual-rotor degassing box and a dual-stage plate filter box and then transported to a casting mold. After casting is completed and annealed in an annealing furnace, an aluminum alloy rod is obtained.

7. The method for preparing an aluminum alloy according to claim 6, characterized in that, In step 303, before refining the aluminum alloy liquid, a sample is taken from the settling furnace and the composition of the aluminum alloy liquid is analyzed using a spectrometer. When the weight percentage of each element is within the preset standard range, refining is carried out. When the weight percentage of each element is outside the preset standard range, one or more of the following are added to the aluminum alloy liquid: aluminum ingot, magnesium powder, zinc powder, aluminum-silicon alloy, Al-Y-La first intermediate alloy, Al-CNT second intermediate alloy, aluminum-titanium-boron wire, and electrolytic copper, until the weight percentage of each element in the aluminum alloy liquid is within the preset standard range.

8. A seamless tubing for oil drilling pipes, characterized in that, It includes a pipe body and an anti-corrosion layer coated on the inner and outer peripheries of the pipe body, wherein the pipe body is made of aluminum alloy as described in any one of claims 1-5, and the anti-corrosion layer is made of acrylic cationic emulsion.

9. A seamless tubing for oil drilling pipe according to claim 8, characterized in that, The acrylic cationic emulsion, by weight, consists of the following components: 35-55 parts methyl methacrylate, 8-12 parts ethyl acrylate, 12-25 parts aqueous solution of functional monomers, 5-10 parts emulsifier, 8-15 parts initiator, and the balance being water. The functional monomer aqueous solution is an aqueous solution of polymerizable polyhydroxy organic amine monomer and N-hydroxyethyl acrylamide in a mass ratio of 4:1.

5.

10. A seamless tubing for oil drilling pipe according to claim 9, characterized in that, The preparation method of the acrylic cationic emulsion includes the following steps: Step 401. Methyl methacrylate and ethyl acrylate are added to the dispersant in sequence and dispersed evenly. Then, the mixture is transferred to the reaction vessel and activated by stirring at 1000 rpm for 10 minutes in a water bath at 60-75℃ to obtain the activated resin mixture. Step 402. Add the functional monomer aqueous solution, emulsifier, initiator and water sequentially to the activated resin mixture prepared in step 401. React for 1-2 hours under a helium atmosphere at -0.05 MPa, 90-100℃ and 1600 rpm to obtain an acrylic cationic emulsion.

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