Metal pipe and preparation method thereof

Abstract

The invention relates to a metal pipe and a preparation method thereof.The preparation method of the metal pipe comprises the steps that the pipe is obtained, the pipe comprises an inner surface and an outer surface, and argon arc welding treatment is conducted on the pipe so that the inner surface of the pipe can be welded; after the pipe is rotated by a preset angle in the axial direction, the pipe is pretreated, and a groove is formed in the outer surface of the pipe; carrying out submerged-arc welding treatment on the outer surface of the pipe so as to fill a groove of the pipe with a welding material; and carrying out heat treatment on the pipe to obtain the target metal pipe.

Description

Technical Field

[0001] The present invention relates to the technical field of metal pipes, and in particular to a metal pipe and a preparation method thereof. Background Art

[0002] Pipelines for transporting high-pressure hydrogen usually use seamless welding or resistance welding, but due to limitations in raw materials and processes, the steel pipe performance of the high-pressure hydrogen storage and transmission pipelines and the structural properties of the welds cannot be guaranteed, making it difficult to carry out large-scale stable production. Summary of the invention

[0003] In view of this, the present invention provides a metal pipe and a preparation method thereof.

[0004] Specifically, the present invention is achieved through the following technical solutions:

[0005] According to a first aspect of the present invention, an embodiment of the present invention provides a method for preparing a metal pipe, the method comprising: obtaining a pipe, the pipe comprising an inner surface and an outer surface, performing argon arc welding on the pipe to weld the inner surface of the pipe; after rotating the pipe axially by a preset angle, pre-treating the pipe to form a groove on the outer surface of the pipe; performing submerged arc welding on the outer surface of the pipe to fill the welding material in the groove of the pipe; and performing heat treatment on the pipe to obtain a target metal pipe.

[0006] In this embodiment, the pipe is subjected to argon arc welding to weld the inner surface of the pipe, and after the pipe is rotated axially by a preset angle, the pipe is pretreated and a groove is formed on the outer surface of the pipe, and the outer surface of the pipe is subjected to submerged arc welding to fill the welding material in the groove of the pipe, and the pipe is heat treated to obtain the target metal pipe. On the basis of resistance welding, argon arc welding and submerged arc welding can be combined to realize continuous production of forming and preparation of smaller diameter steel pipes, eliminate undesirable martensite and banded structures in the pipe and weld, reduce the inherent residual stress of the steel pipe, achieve homogenization of the overall performance structure of the steel pipe, ensure the continuous stability and mechanical properties of the weld, improve the purity of the steel pipe, meet the transportation requirements of hydrogen, and ensure the clean and pure supply of energy.

[0007] In some embodiments of the present invention, performing argon arc welding on the pipe to weld the inner surface of the pipe includes: performing argon arc welding on the pipe to weld the inner surface of the pipe according to a first preset current and a first preset voltage.

[0008] In this embodiment, the pipe is subjected to argon arc welding according to the first preset current and the first preset voltage to complete the internal welding of the hydrogen pipeline. The first preset current and the first preset voltage can control the quality of the weld, thereby ensuring that the weld is continuous, stable and uniform, and meeting the performance requirements of hydrogen transportation.

[0009] In some embodiments of the present invention, the value range of the first preset current is greater than or equal to 350A and less than or equal to 400A; the value range of the first preset voltage is greater than or equal to 20V and less than or equal to 24V.

[0010] In this embodiment, the value range of the first preset current is set to be greater than or equal to 350 and less than or equal to 400 amperes, and the value range of the first preset voltage is set to be greater than or equal to 20 volts and less than or equal to 24 volts, which can ensure that the welding material reaches a molten state on the pipe while meeting safety specifications.

[0011] In some embodiments of the present invention, the pipe is pretreated to form a groove on the outer surface of the pipe, including: grinding the outer surface of the pipe; spraying a nitric acid solution with a preset mass fraction on the grinded outer surface at a preset spraying speed to mark a preset groove position on the outer surface; processing the outer surface at the preset groove position to form a groove with a preset angle and a preset depth.

[0012] In this embodiment, the outer surface of the pipe is polished, and a nitric acid solution with a preset mass fraction is sprayed on the polished outer surface at a preset spraying speed to mark the preset groove position of the outer surface, and the outer surface is processed at the preset groove position to form a groove of a preset angle and a preset depth, which can reduce the roughness of the surface of the pipe. After spraying the nitric acid solution at a uniform speed, the preset groove position of the outer surface is marked while ensuring that the contour is clear and discernible, and the preset groove position is marked on the outer surface that passes through at a uniform speed and in parallel, and a groove that meets the welding process requirements is processed to avoid deviation between the internal and external welding processes, thereby ensuring the fusion effect of the internal and external welds.

[0013] In some embodiments of the present invention, the preset spraying speed has a value range of greater than or equal to 0.5 ml per minute and less than or equal to 0.8 ml per minute; the preset mass fraction has a value range of greater than or equal to 85% and less than or equal to 95%.

[0014] In this embodiment, the value range of the preset spray speed is set to be greater than or equal to 0.5 ml per minute and less than or equal to 0.8 ml per minute, and the value range of the preset mass fraction is set to be greater than or equal to 85% and less than or equal to 95%. This can ensure the spraying and developing effects of the nitric acid solution on the surface of the pipe, ensure the marking of the preset groove position, facilitate the combination of internal welding and external welding, and facilitate the continuous preparation of smaller diameter hydrogen transmission steel pipes, thereby meeting the process preparation requirements.

[0015] In some embodiments of the present invention, the value range of the preset angle is greater than or equal to 30 degrees and less than or equal to 60 degrees; the value range of the preset depth is greater than or equal to 3 mm and less than or equal to 10 mm.

[0016] In this embodiment, the value range of the preset angle is set to be greater than or equal to 30 degrees and less than or equal to 60 degrees, and the value range of the preset depth is set to be greater than or equal to 3 mm and less than or equal to 10 mm, which can ensure that the groove meets the welding requirements, thereby facilitating submerged arc welding to fill the groove, ensure the quality and mechanical properties of the weld, and facilitate the transportation of hydrogen.

[0017] In some embodiments of the present invention, before machining the outer surface at a preset groove position to form a groove with a preset angle and a preset depth, the method further includes: sizing the two end faces of the pipe.

[0018] In this embodiment, the two end faces of the pipe are sizing treated to ensure the flatness of the two end faces of the pipe and meet the process manufacturing requirements of the hydrogen transmission pipeline.

[0019] In some embodiments of the present invention, before obtaining the pipe, the step further includes: removing burrs on the inner surface of the pipe.

[0020] In this embodiment, the burrs on the inner surface of the pipe are removed, and non-metallic extrusions produced by the extrusion of the inside and outside of the pipe during resistance welding can be removed, thereby ensuring the welding quality and meeting the process manufacturing requirements of the hydrogen transmission pipeline.

[0021] In some embodiments of the present invention, before removing the burrs on the inner surface of the tube, the method further includes: performing forming and welding processing on the plate to obtain the tube.

[0022] In this embodiment, the sheet is subjected to forming and welding treatment, and the tension effect generated during roller forming can be utilized to add the bending moment to the edge to the maximum extent, thereby providing good edge conditions for high-frequency welding by adjusting the working plate width and the roller parameters of the rough forming frame and utilizing the characteristics of the roller involute, thereby improving the ductility of the sheet and making the sheet fully formed. The two end faces of the edge of the sheet can be parallelly butted, so that after high-frequency resistance welding, uniform burrs are formed on the inner and outer surfaces, which is conducive to scraping and breaking the burrs.

[0023] In some embodiments of the present invention, the components of the plate include at least: carbon, silicon, manganese, nickel, chromium, molybdenum, and iron.

[0024] In this embodiment, lower carbon, manganese, sulfur and phosphorus are used in the plate, and higher nickel, molybdenum, chromium, etc. are used, which can effectively avoid stress corrosion, control the usage ratio of manganese and silicon, and reduce the melting point of the inevitable oxides in the weld during resistance welding, thereby discharging them, which is beneficial to improving the hardenability of the steel, lowering the critical point and increasing the stability of austenite, lowering its quenching temperature, and preventing grain growth at high temperatures, maintaining a fine grain structure, and improving the tempering stability of the steel, so that carbides are precipitated during heat treatment, thereby increasing the strength of the steel, improving the precipitation strengthening effect, avoiding the adverse effects that may be caused by a single element, and playing a role in improving segregation, solid solution strengthening, and increasing the hardenability during heat treatment.

[0025] In some embodiments of the present invention, the sheet is subjected to forming and welding treatment to obtain a pipe, including: roller forming the sheet through a center bending deformation method, and high-frequency induction welding of the radial weld of the formed sheet rolled into a tube blank to obtain the pipe.

[0026] In this embodiment, the central bending deformation method is used to roll the plate and perform high-frequency induction welding on the radial weld of the formed plate rolled into a tube blank to obtain a tube. The central bending deformation method is a roll forming method. The plate is roll formed, and the tension effect generated during roll forming can be used to maximize the bending moment added to the edge. Thus, by adjusting the working plate width and the roller parameters of the rough forming frame, the characteristics of the roller involute are used to provide good edge conditions for high-frequency welding, improve the ductility of the plate, and make the plate fully formed. The two end faces of the edge of the plate can be parallel to the workpiece, which is convenient for forming uniform burrs on the inner and outer surfaces after high-frequency resistance welding, which is conducive to scraping and breaking the burrs. The formed plate is subjected to induction welding to ensure the stability of welding and the stability and uniformity of the weld.

[0027] In some embodiments of the present invention, submerged arc welding is performed on the outer surface of the pipe to fill the welding material in the groove of the pipe, including: direct current welding is performed on the pipe according to a second preset current and a second preset voltage, and alternating current welding is performed on the pipe according to a third preset current and a third preset voltage to fill the welding material in the groove of the pipe.

[0028] In this embodiment, the first wire submerged arc welding automatic welding process is performed on the pipe by the second preset current and the second preset voltage, which can control the weld formation, and the second wire submerged arc welding automatic welding process is performed on the pipe by the third preset current and the third preset voltage. Then, the double-wire submerged arc welding process is used to solve the problem that resistance welding continuous production is difficult to match in related technologies, while ensuring the process performance of the pipe to meet the transportation needs of pure hydrogen.

[0029] In some embodiments of the present invention, the second preset current has a value range of greater than or equal to 800A and less than or equal to 1300A; the second preset voltage has a value range of greater than or equal to 30V and less than or equal to 33V;

[0030] In this embodiment, the value range of the second preset current is set to be greater than or equal to 800 amps and less than or equal to 1300 amps, and the value range of the second preset voltage is set to be greater than or equal to 30 volts and less than or equal to 33 volts, so that the submerged arc welding of the first wire can be controlled, thereby ensuring the stability of the weld.

[0031] In some embodiments of the present invention, the value range of the third preset current is greater than or equal to 400A and less than or equal to 600A; the value range of the third preset voltage is greater than or equal to 32V and less than or equal to 35V.

[0032] In this embodiment, the value range of the third preset current is set to be greater than or equal to 400 amps and less than or equal to 600 amps, and the value range of the third preset voltage is set to be greater than or equal to 32 volts and less than or equal to 35 volts, so that the submerged arc welding of the second wire can be controlled, thereby ensuring the forming stability of the weld.

[0033] In some embodiments of the present invention, heat treating the tube to obtain the target metal tube includes: normalizing the tube at a first preset temperature, and annealing the normalized tube at a preset temperature drop rate to obtain the target metal tube.

[0034] In this embodiment, the pipe is subjected to normalizing treatment at a first preset temperature, so that the weld structure after normalizing treatment is uniform, the grains of the weld and the heat-affected zone are refined, and the hardness of the weld is reduced. The pipe after normalizing treatment is subjected to annealing treatment at a preset temperature drop rate, which can eliminate martensite and banded undesirable structures in the pipe and weld area, reduce the inherent residual stress of the steel pipe, make the overall performance structure of the target metal pipe homogenized, reduce the corrosion sensitivity coefficient at the weld, and reduce the tendency of stress corrosion.

[0035] In some embodiments of the present invention, the preset temperature rise rate of the first preset temperature has a value range of greater than or equal to 50 degrees Celsius per second and less than or equal to 80 degrees Celsius per second.

[0036] In this embodiment, the value range of the preset temperature rise rate of the first preset temperature is set between greater than or equal to 50 degrees Celsius per second and less than or equal to 80 degrees Celsius per second, and the steel pipe can be normalized by medium frequency induction heating, thereby ensuring uniform weld structure, refining the grains of the weld and the heat affected zone, and reducing the weld hardness.

[0037] In some embodiments of the present invention, the first preset temperature has a value range of greater than or equal to 500 degrees Celsius and less than or equal to 1000 degrees Celsius.

[0038] In this embodiment, the value range of the first preset temperature is set to be greater than or equal to 500 degrees Celsius and less than or equal to 1000 degrees Celsius, which can ensure that the pipe and the weld are completely normalized, thereby refining the grains of the weld and the heat-affected zone and reducing the hardness of the weld.

[0039] In some embodiments of the present invention, the preset temperature drop rate has a value range of greater than or equal to 3 degrees Celsius per second and less than or equal to 8 degrees Celsius per second.

[0040] In this embodiment, the preset temperature drop rate is set within a range of greater than or equal to 3 degrees Celsius per second and less than or equal to 8 degrees Celsius per second, which can ensure complete annealing, thereby eliminating martensite and banded undesirable structures in the pipe and weld area, reducing the inherent residual stress of the steel pipe, making the overall performance structure of the target metal pipe homogenized, reducing the corrosion sensitivity coefficient at the weld, and reducing the tendency of stress corrosion.

[0041] According to a second aspect of the present invention, a metal pipe is provided. The metal pipe is made by the metal pipe making method according to the first aspect.

[0042] The metal pipe of the present invention is made by the preparation method of the metal pipe of the first aspect, and has all the beneficial technical effects of the first aspect or any possible implementation method of the first aspect, which will not be repeated here.

[0043] The technical solution provided by the present invention brings at least the following beneficial effects: the present invention performs argon arc welding on the pipe to weld the inner surface of the pipe, rotates the pipe axially by a preset angle, pre-treats the pipe, forms a groove on the outer surface of the pipe, performs submerged arc welding on the outer surface of the pipe to fill the welding material in the groove of the pipe, and heat treats the pipe to obtain the target metal pipe. On the basis of resistance welding, argon arc welding and submerged arc welding can be combined to realize continuous production of forming and preparation of smaller-diameter steel pipes, eliminate undesirable martensite and banded structures in the pipe and weld, reduce the inherent residual stress of the steel pipe, achieve homogenization of the overall performance structure of the steel pipe, ensure the continuous stability and mechanical properties of the weld, improve the purity of the steel pipe, meet the transportation requirements of hydrogen, and ensure the clean and pure supply of energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or related technical descriptions are briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0046] Figure 1 One of the schematic flow diagrams of the method for preparing a metal pipe provided in an embodiment of the present invention;

[0047] Figure 2 A second schematic flow chart of a method for preparing a metal pipe provided in an embodiment of the present invention;

[0048] Figure 3 A schematic diagram of a method for preparing a metal pipe provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] See also Figure 1 The embodiment of the present invention provides a method for preparing a metal pipe, the method for preparing a metal pipe comprising:

[0051] S102, obtaining a pipe, the pipe including an inner surface and an outer surface, and performing argon arc welding on the pipe to weld the inner surface of the pipe;

[0052] In this embodiment, a metal pipe preparation method is provided for preparing a small-diameter metal pipe, obtaining the pipe, wherein the pipe includes an inner surface and an outer surface, and performing argon arc welding on the pipe to weld the inner surface of the pipe.

[0053] For example, the pipe material is obtained on the basis of ERW (Electric Resistance Welding) prefabricated steel pipe, because this embodiment is to use the manufactured ERW steel pipe as the "workpiece" for further welding, mainly to overcome the problem that ERW steel pipe cannot be welded with carbon steel pipe with high alloy content, and to make up for the problem that the inner diameter of the welded steel pipe is too small to meet the internal welding. Therefore, this embodiment abandons the original conventional method of submerged arc welding for both internal and external welding, and adopts a small wire diameter and lightweight argon arc welding method for internal welding.

[0054] Exemplarily, the pipe material may be a prefabricated steel pipe, which is a tube blank formed by continuous strip-shaped rolled plate, the tube blank is O-shaped, and includes two longitudinal edges of the rolled plate welded to the edges of the steel plate to form the prefabricated steel pipe.

[0055] Exemplarily, the preset distance can reserve welding positions between pipes. In the continuous production process, pipes are welded in sequence at the reserved welding positions to obtain hydrogen transport steel pipes that meet process requirements and production requirements. The diameter of the pipe used in the present invention is between 200 mm and 400 mm. It can be combined with internal and external distributed welding on the basis of resistance welding forming, and adopts overall heat treatment to eliminate stress and banded structure in the weld, improve the purity of the steel pipe, ensure the stability and reliability of the weld structure and alloy composition, achieve homogenization of the weld structure performance of the pipe body, improve the pipe under high pressure, such as 10 MPa pure hydrogen transportation, alleviate the greenhouse effect, ensure the clean and pure supply of energy, and then facilitate large-scale continuous production to meet production and transportation requirements.

[0056] Illustratively, the argon arc welding process is used to perform internal welding on the pipes in sequence, which can melt the weld material into a liquid state on the pipes. While the pipes and the weld material achieve metallurgical bonding, argon gas can be continuously supplied to reduce the contact between the weld material and oxygen in the air, prevent oxidation of the weld material, isolate the adverse effects of nitrogen, hydrogen, etc. on the arc and the molten pool, reduce the burning of alloy elements, reduce spatter, deformation and crack tendency, ensure density, and ensure welding quality, facilitate mechanized and automated continuous operation, and perform all-position welding without being restricted by welding position.

[0057] S104, after rotating the pipe in the axial direction by a preset angle, pre-treating the pipe to form a groove on the outer surface of the pipe;

[0058] After the pipe is rotated axially by a preset angle, the pipe is pre-processed and a groove is formed on the outer surface of the pipe.

[0059] Exemplarily, the preset angle may be specifically 180 degrees, and the pipe is pre-processed after being rotated 180 degrees.

[0060] Exemplarily, the pipe is pretreated to reduce the roughness of the pipe surface and ensure that the prefabricated weld is clearly visible, thereby marking the characteristic line at the end of the pipe, providing a reference point for welding, avoiding mutual deviation during internal and external welding, ensuring the fusion effect of internal and external welding, and at the same time ensuring the size of the pipe diameter, the ovality of the pipe and the accuracy of the pipe. According to the actual process requirements, a groove of a certain shape is formed at the position to be welded to form a groove, which is convenient for subsequent external connection of the pipe, and is conducive to flaw detection while ensuring the welding degree. The present invention does not impose strict restrictions on the specific shape of the groove. Under the condition of meeting production needs and process requirements, the specific shape of the groove can be flexibly set.

[0061] S106, performing submerged arc welding on the outer surface of the pipe to fill the welding material into the groove of the pipe;

[0062] Submerged arc welding is performed on the outer surface of the pipe to fill the welding material in the groove of the pipe, reduce heat radiation loss and spatter, improve production efficiency, facilitate the continuous production of small-diameter welded steel pipes, and at the same time ensure the continuity and stability of the weld and the mechanical properties of the weld.

[0063] S108, heat treating the pipe to obtain the target metal pipe.

[0064] The pipe is heat treated to obtain the target metal pipe. The overall heat treatment of the pipe can perform high-temperature tempering heating on the weld to eliminate the undesirable martensite and banded structure in the pipe and the weld, reduce the inherent residual stress of the steel pipe, and achieve the homogenization of the overall performance structure of the steel pipe to meet the production and processing requirements.

[0065] In this embodiment, the pipe is subjected to argon arc welding to weld the inner surface of the pipe, and after the pipe is rotated axially by a preset angle, the pipe is pretreated and a groove is formed on the outer surface of the pipe, and the outer surface of the pipe is subjected to submerged arc welding to fill the welding material in the groove of the pipe, and the pipe is heat treated to obtain the target metal pipe. On the basis of resistance welding, argon arc welding and submerged arc welding can be combined to realize continuous production of forming and preparation of smaller diameter steel pipes, eliminate undesirable martensite and banded structures in the pipe and weld, reduce the inherent residual stress of the steel pipe, achieve homogenization of the overall performance structure of the steel pipe, ensure the continuous stability and mechanical properties of the weld, improve the purity of the steel pipe, meet the transportation requirements of hydrogen, and ensure the clean and pure supply of energy.

[0066] In some embodiments of the present invention, performing argon arc welding on the pipe to weld the inner surface of the pipe includes: performing argon arc welding on the pipe to weld the inner surface of the pipe according to a first preset current and a first preset voltage.

[0067] In this embodiment, the pipe is subjected to argon arc welding according to the first preset current and the first preset voltage to complete the internal welding of the hydrogen pipeline. The first preset current and the first preset voltage can control the quality of the weld, thereby ensuring that the weld is continuous, stable and uniform, and meeting the performance requirements of hydrogen transportation.

[0068] In some embodiments of the present invention, the value range of the first preset current is greater than or equal to 350A and less than or equal to 400A; the value range of the first preset voltage is greater than or equal to 20V and less than or equal to 24V.

[0069] In this embodiment, the value range of the first preset current is set to be greater than or equal to 350 and less than or equal to 400 amperes, and the value range of the first preset voltage is set to be greater than or equal to 20 volts and less than or equal to 24 volts, which can ensure that the welding material reaches a molten state on the pipe while meeting safety specifications.

[0070] It is understandable that the present invention does not impose strict restrictions on the specific values ​​of the preset current and the preset voltage. Under the condition of meeting production requirements and safety process requirements, the specific values ​​of the preset current and the preset voltage can be flexibly set.

[0071] The present invention does not impose strict restrictions on the specific types of welding materials, the components of welding materials and argon arc welding machines. The welding materials and welding machines can be flexibly set while meeting production requirements.

[0072] See also Figure 2 In some embodiments of the present invention, pre-treating the pipe to form a groove on the outer surface of the pipe includes:

[0073] S202, grinding the outer surface of the pipe;

[0074] A belt grinding device can be selected to grind the outer surface of the pipe to reduce the roughness of the pipe surface and facilitate the identification of characteristic lines.

[0075] For example, three groups of 500-mesh sand belts and 800-mesh sand belts can be used for grinding, and a negative pressure dust removal device can be installed to ensure that the iron filings generated by grinding are fully recovered. With the cooperation of the servo motor and the sensor, the grinding and polishing of the prefabricated weld of the steel pipe is completed under high-speed rotation. The specific speed can be set between 60 and 80 revolutions per minute. The present invention does not strictly limit the specific value of the specific speed. The specific speed can be reasonably selected under the condition of meeting the process requirements.

[0076] It is understandable that when grinding the outer surface of the pipe, a walking clamping device can be used to ensure that the pipe can move relatively in a stable state and that multiple groups of sanding belts are in good contact with the steel pipe while ensuring that the grinding device does not move.

[0077] S204, spraying a nitric acid solution with a preset mass fraction on the polished outer surface at a preset spraying speed to mark a preset groove position of the outer surface;

[0078] Spray nitric acid solution on the polished outer surface, apply it at a uniform speed, and mark the preset groove position of the outer surface while ensuring the outline is clearly discernible. This can provide a reference benchmark for welding, avoid deviation between internal and external welding processes, and ensure the fusion effect of internal and external welding.

[0079] For example, three groups of cellulose cotton brushes can be set with an acid spray head with a matching size of 10 mm, and the acid spray can be applied at a uniform speed of 85 revolutions per minute. The present invention does not strictly limit the specific structure, specific type and specific process parameters of the spraying device, and a reasonable selection can be made under the condition of meeting the process requirements.

[0080] S206: Processing the outer surface at a preset groove position to form a groove with a preset angle and a preset depth.

[0081] The vertical milling cutter that rotates at high speed and is adjustable in position at the preset groove position processes the outer surface, cooperates with the external clamping device and the horizontally moving transport trolley, and the running speed of the transport trolley is the first preset speed. When the transport trolley is running, a groove that meets the welding process requirements is processed. The running speed of the trolley can be set within the range of greater than or equal to 0.8 meters per minute and less than or equal to 1 meter per minute. The present invention does not strictly limit the specific value of the trolley running speed. Under the condition of meeting the process requirements and uniform speed requirements, the specific value of the running speed can be flexibly set.

[0082] In this embodiment, the outer surface of the pipe is polished, and a nitric acid solution with a preset mass fraction is sprayed on the polished outer surface at a preset spraying speed to mark the preset groove position of the outer surface, and the outer surface is processed at the preset groove position to form a groove of a preset angle and a preset depth, which can reduce the roughness of the surface of the pipe. After spraying the nitric acid solution at a uniform speed, the preset groove position of the outer surface is marked while ensuring that the contour is clear and discernible, and the preset groove position is marked on the outer surface that passes through at a uniform speed and in parallel, and a groove that meets the welding process requirements is processed to avoid deviation between the internal and external welding processes, thereby ensuring the fusion effect of the internal and external welds.

[0083] For example, Figure 3 As shown, Figure 3 Schematic diagram of pipe manufacturing.

[0084] In some embodiments of the present invention, the preset spraying speed has a value range of greater than or equal to 0.5 ml per minute and less than or equal to 0.8 ml per minute; the preset mass fraction has a value range of greater than or equal to 85% and less than or equal to 95%.

[0085] In this embodiment, the value range of the preset spray speed is set to be greater than or equal to 0.5 ml per minute and less than or equal to 0.8 ml per minute, and the value range of the preset mass fraction is set to be greater than or equal to 85% and less than or equal to 95%. This can ensure the spraying and development effects of the nitric acid solution on the outer surface, ensure the marking of the preset groove position, facilitate the combination of internal welding and external welding, and facilitate the continuous preparation of smaller diameter hydrogen transmission steel pipes, thereby meeting the process preparation requirements.

[0086] In some embodiments of the present invention, the value range of the preset angle is greater than or equal to 30 degrees and less than or equal to 60 degrees; the value range of the preset depth is greater than or equal to 3 mm and less than or equal to 10 mm.

[0087] In this embodiment, the value range of the preset angle is set to be greater than or equal to 30 degrees and less than or equal to 60 degrees, and the value range of the preset depth is set to be greater than or equal to 3 mm and less than or equal to 10 mm, which can ensure that the groove meets the welding requirements, thereby facilitating submerged arc welding to fill the groove, ensure the quality and mechanical properties of the weld, and facilitate the transportation of hydrogen.

[0088] The present invention does not impose strict restrictions on the specific value of the preset angle and / or the specific value of the preset depth. The preset angle and / or preset depth can be flexibly selected while satisfying the process requirements and welding requirements.

[0089] In some embodiments of the present invention, before machining the outer surface at a preset groove position to form a groove with a preset angle and a preset depth, the method further includes: sizing the two end faces of the pipe.

[0090] In this embodiment, the two end faces of the pipe are sizing treated to ensure the flatness of the two end faces of the pipe and meet the process manufacturing requirements of the hydrogen transmission pipeline.

[0091] In some embodiments of the present invention, before obtaining the pipe, the step further includes: removing burrs on the inner surface of the pipe.

[0092] In this embodiment, the burrs on the inner surface of the pipe are removed, and non-metallic extrusions produced by the extrusion of the inside and outside of the pipe during resistance welding can be removed, thereby ensuring the welding quality and meeting the process manufacturing requirements of the hydrogen transmission pipeline.

[0093] In some embodiments of the present invention, before removing the burrs on the inner surface of the tube, the method further includes: performing forming and welding processing on the plate to obtain the tube.

[0094] In this embodiment, the sheet is subjected to forming and welding treatment, and the tension effect generated during roller forming can be utilized to add the bending moment to the edge to the maximum extent, thereby providing good edge conditions for high-frequency welding by adjusting the working plate width and the roller parameters of the rough forming frame and utilizing the characteristics of the roller involute, thereby improving the ductility of the sheet and making the sheet fully formed. The two end faces of the edge of the sheet can be parallelly butted, so that after high-frequency resistance welding, uniform burrs are formed on the inner and outer surfaces, which is conducive to scraping and breaking the burrs.

[0095] It is understandable that the extrusion amount during the forming process can be controlled between 4 mm and 6 mm, and the sizing amount can be set between 6 mm and 10 mm, so as to ensure that the pipe has good roundness and low residual stress after forming, avoiding the occurrence of stress corrosion.

[0096] The present invention does not impose strict restrictions on the specific values ​​of the extrusion amount and the sizing amount. Under the condition of meeting the process requirements, they can be reasonably set according to the actual situation.

[0097] It is understood that resistance welding is high-frequency induction welding. The resistance welding adjustment and control of the weld extrusion amount can be controlled at 4.5 mm, so that the pipe forms a weld metal flow rise angle between 60 degrees and 80 degrees, so that the welding speed can be easily controlled, so that the welding speed is within a certain range, ensuring the stability of the welding and the stability and uniformity of the weld. The welding speed can be controlled between 15 meters per minute and 20 meters per minute, and the welding frequency is controlled between 350 kHz and 450 kHz, so as to obtain a high-strength and high-toughness weld.

[0098] The present invention does not impose strict restrictions on the specific values ​​of the welding speed, welding frequency, rise angle and extrusion amount. Under the condition of meeting the process requirements, they can be reasonably set according to the actual situation.

[0099] In some embodiments of the present invention, the components of the plate include at least: carbon, silicon, manganese, sulfur, phosphorus, nickel, chromium, molybdenum, and iron.

[0100] In this embodiment, lower carbon, manganese, sulfur and phosphorus are used in the plate, and higher nickel, molybdenum, chromium, etc. are used, which can effectively avoid stress corrosion, control the usage ratio of manganese and silicon, and reduce the melting point of the inevitable oxides in the weld during resistance welding, thereby discharging them, which is beneficial to improving the hardenability of the steel, lowering the critical point and increasing the stability of austenite, lowering its quenching temperature, and preventing grain growth at high temperatures, maintaining a fine grain structure, and improving the tempering stability of the steel, so that carbides are precipitated during heat treatment, thereby increasing the strength of the steel, improving the precipitation strengthening effect, avoiding the adverse effects that may be caused by a single element, and playing a role in improving segregation, solid solution strengthening, and increasing the hardenability during heat treatment.

[0101] For example, as shown in Table 1:

[0102] Table 1

[0103]

[0104]

[0105] Table 1 shows the specific composition of the base material and the welding material in the embodiment of the present invention. The mass percentage of carbon can be set between 0.05% and 0.1%, the mass percentage of manganese can be set between 0.8% and 1.5%, the mass percentage of silicon can be set between 0.1% and 0.3%, the mass percentage of chromium can be set between 0.1% and 0.3%, the mass percentage of nickel can be set between 1.0% and 1.5%, the mass percentage of molybdenum can be set between 0.3% and 0.5%, the mass percentage of phosphorus can be set to be less than or equal to 0.010%, and the mass percentage of sulfur can be set to be less than or equal to 0.010%. The percentage is set to be less than or equal to 0.005%, so that the melting point of the inevitable oxides in the weld during resistance welding can be reduced, thereby causing them to be discharged, which is beneficial to improving the hardenability of the steel, reducing the critical point and increasing the stability of austenite, reducing its quenching temperature, and preventing the growth of grains at high temperatures, maintaining a fine grain structure, and improving the tempering stability of the steel, so that carbides are precipitated during heat treatment, thereby increasing the strength of the steel, improving the precipitation strengthening effect, avoiding the adverse effects that may be caused by a single element, and playing a role in improving segregation, solid solution strengthening, and increasing the hardenability during heat treatment.

[0106] The carbon equivalent can be set between 0.18 and 0.21. The carbon equivalent is the effect of converting other elements into carbon elements, which can be used to predict the extent of cold cracking of steel during welding. The present invention does not impose strict restrictions on the specific value of the carbon equivalent. Under the condition of meeting the process requirements, the setting range of the carbon equivalent can be reasonably selected.

[0107] In some embodiments of the present invention, the sheet is subjected to forming and welding treatment to obtain a pipe, including: roller forming the sheet through a center bending deformation method, and high-frequency induction welding of the radial weld of the formed sheet rolled into a tube blank to obtain the pipe.

[0108] In this embodiment, the central bending deformation method is used to roll the plate and perform high-frequency induction welding on the radial weld of the formed plate rolled into a tube blank to obtain a tube. The central bending deformation method is a roll forming method. The plate is roll formed, and the tension effect generated during roll forming can be used to maximize the bending moment added to the edge. Thus, by adjusting the working plate width and the roller parameters of the rough forming frame, the characteristics of the roller involute are used to provide good edge conditions for high-frequency welding, improve the ductility of the plate, and make the plate fully formed. The two end faces of the edge of the plate can be parallel to the workpiece, which is convenient for forming uniform burrs on the inner and outer surfaces after high-frequency resistance welding, which is conducive to scraping and breaking the burrs. The formed plate is subjected to induction welding to ensure the stability of welding and the stability and uniformity of the weld.

[0109] In some embodiments of the present invention, submerged arc welding is performed on the outer surface of the pipe to fill the welding material in the groove of the pipe, including: direct current welding is performed on the pipe according to a second preset current and a second preset voltage, and alternating current welding is performed on the pipe according to a third preset current and a third preset voltage to fill the welding material in the groove of the pipe.

[0110] In this embodiment, the first wire submerged arc welding automatic welding process is performed on the pipe by the second preset current and the second preset voltage, which can control the weld formation, and the second wire submerged arc welding automatic welding process is performed on the pipe by the third preset current and the third preset voltage. Then, the double-wire submerged arc welding process is used to solve the problem that resistance welding continuous production is difficult to match in related technologies, while ensuring the process performance of the pipe to meet the transportation needs of pure hydrogen.

[0111] In the process of double-wire submerged arc welding, the distance between the second wire and the first wire can be controlled to be between 15 mm and 20 mm, and the submerged arc welding can be performed at a welding speed of 1 meter per minute to 1.6 meters per minute. The present invention does not impose strict restrictions on the distance between the front and rear wires and the welding speed. The distance and the welding speed can be reasonably set while meeting the process requirements.

[0112] In some embodiments of the present invention, the second preset current has a value range of greater than or equal to 800A and less than or equal to 1300A; the second preset voltage has a value range of greater than or equal to 30V and less than or equal to 33V;

[0113] In this embodiment, the value range of the second preset current is set to be greater than or equal to 800 amps and less than or equal to 1300 amps, and the value range of the second preset voltage is set to be greater than or equal to 30 volts and less than or equal to 33 volts, so that the submerged arc welding of the first wire can be controlled, thereby ensuring the stability of the weld.

[0114] In some embodiments of the present invention, the value range of the third preset current is greater than or equal to 400A and less than or equal to 600A; the value range of the third preset voltage is greater than or equal to 32V and less than or equal to 35V.

[0115] In this embodiment, the value range of the third preset current is set to be greater than or equal to 400 amps and less than or equal to 600 amps, and the value range of the third preset voltage is set to be greater than or equal to 32 volts and less than or equal to 35 volts, so that the submerged arc welding of the second wire can be controlled, thereby ensuring the forming stability of the weld.

[0116] In some embodiments of the present invention, heat treating the tube to obtain the target metal tube includes: normalizing the tube at a first preset temperature, and annealing the normalized tube at a preset temperature drop rate to obtain the target metal tube.

[0117] In this embodiment, the pipe is subjected to normalizing treatment at a first preset temperature, so that the weld structure after normalizing treatment is uniform, the grains of the weld and the heat-affected zone are refined, and the hardness of the weld is reduced. The pipe after normalizing treatment is subjected to annealing treatment at a preset temperature drop rate, which can eliminate martensite and banded undesirable structures in the pipe and weld area, reduce the inherent residual stress of the steel pipe, make the overall performance structure of the target metal pipe homogenized, reduce the corrosion sensitivity coefficient at the weld, and reduce the tendency of stress corrosion.

[0118] In some embodiments of the present invention, the preset temperature rise rate of the first preset temperature has a value range of greater than or equal to 50 degrees Celsius per second and less than or equal to 80 degrees Celsius per second.

[0119] In this embodiment, the value range of the preset temperature rise rate of the first preset temperature is set between greater than or equal to 50 degrees Celsius per second and less than or equal to 80 degrees Celsius per second, and the steel pipe can be normalized by medium frequency induction heating, thereby ensuring uniform weld structure, refining the grains of the weld and the heat affected zone, and reducing the weld hardness.

[0120] The present invention does not impose strict restrictions on the specific value of the preset temperature rise rate and the specific frequency of the medium frequency heating. The specific value of the preset temperature rise rate and the specific frequency of the medium frequency heating can be flexibly set within the range of meeting the process requirements.

[0121] In some embodiments of the present invention, the first preset temperature has a value range of greater than or equal to 500 degrees Celsius and less than or equal to 1000 degrees Celsius.

[0122] In this embodiment, the value range of the first preset temperature is set to be greater than or equal to 500 degrees Celsius and less than or equal to 1000 degrees Celsius, which can ensure that the pipe and the weld are completely normalized, thereby refining the grains of the weld and the heat-affected zone and reducing the hardness of the weld.

[0123] The present invention does not impose strict restrictions on the specific value of the first preset temperature. The specific value of the first preset temperature can be flexibly set while meeting the process requirements.

[0124] In some embodiments of the present invention, the preset temperature drop rate has a value range of greater than or equal to 3 degrees Celsius per second and less than or equal to 8 degrees Celsius per second.

[0125] In this embodiment, the preset temperature drop rate is set within a range of greater than or equal to 3 degrees Celsius per second and less than or equal to 8 degrees Celsius per second, which can ensure complete annealing, thereby eliminating martensite and banded undesirable structures in the pipe and weld area, reducing the inherent residual stress of the steel pipe, making the overall performance structure of the target metal pipe homogenized, reducing the corrosion sensitivity coefficient at the weld, and reducing the tendency of stress corrosion.

[0126] In some embodiments of the present invention, the target metal pipe is inspected after the pipe is normalized and annealed.

[0127] Exemplarily, 100% X-ray inspection is performed on the internal and external welds of the target metal pipe, a hydrostatic test is performed on the target metal pipe, ultrasonic flaw detection is performed on the welds and the target metal pipe, and finished product inspection is performed by filming.

[0128] 100% X-ray inspection of the internal and external welds of the target metal pipe can detect volume defects of the target metal pipe produced during the welding process, such as lack of fusion, beads, pores, cracks, incomplete penetration and other defects, thereby detecting the welding quality. Before transporting hydrogen, timely inspection can be carried out to avoid leakage or other safety risks during the hydrogen transportation process.

[0129] The hydrostatic test can be performed at 14.5 MPa, with a pressure fluctuation of 0 MPa to 0.5 MPa and a pressure stabilization time of more than 15 seconds to determine the water pressure strength and sealing performance of the target metal pipe to avoid leakage or other safety risks during hydrogen transportation.

[0130] Ultrasonic flaw detection of welds and target metal pipes can detect defects and their specific locations in the target metal pipes, improve defects in a timely manner, and avoid leakage or other safety risks during hydrogen transportation.

[0131] After the target metal pipe is subjected to radiographic testing, hydrostatic pressure testing and ultrasonic testing, the pipe section of the target metal pipe is chamfered to facilitate welding between pipes. The processing groove of the chamfer can be set between 22 degrees and 25 degrees, the blunt edge can be set between 0.8 mm and 2.4 mm, and the inner cone angle can be set below 7 degrees.

[0132] It is understandable that the present invention does not impose strict restrictions on the specific parameters and forms of detection. Under the condition of meeting the process requirements, the specific forms of detection and related parameters can be flexibly selected.

[0133] The present invention mainly detects the target metal pipe in terms of strength, toughness, crack corrosion performance, crack opening displacement, etc. Among them, strength includes indicators such as yield strength, tensile strength, and elongation of the pipe body and weld, toughness includes impact toughness of the pipe body and weld and related indicators of drop weight tearing test, crack corrosion performance includes indicators such as crack length percentage, crack thickness percentage, crack sensitivity percentage, etc., and crack opening displacement includes related indicators such as displacement.

[0134] Based on the same inventive concept, the metal pipe of the embodiment of the present invention is made by the preparation method of the metal pipe of any of the above embodiments.

[0135] The metal pipe of the embodiment of the present invention is made by the method for preparing the metal pipe of any of the above embodiments, and has all the beneficial technical effects of the method for preparing the metal pipe of any possible implementation manner described above, which will not be repeated here.

[0136] Although this specification includes many specific implementation details, these should not be interpreted as limiting the scope of any invention or the scope of protection claimed, but are mainly used to describe the features of the specific embodiments of specific inventions. Certain features described in multiple embodiments in this specification may also be implemented in combination in a single embodiment. On the other hand, the various features described in a single embodiment may also be implemented separately in multiple embodiments or in any suitable sub-combination. In addition, although the features may work as above in certain combinations and even initially claim protection, one or more features from the claimed combination may be removed from the combination in some cases, and the claimed combination may point to a sub-combination or a variation of a sub-combination.

[0137] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0138] The above is only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but should conform to the widest scope consistent with the principles and novel features applied herein.

Claims

1. A method for preparing a metal pipe, characterized in that: The metal pipe preparation method comprises: Obtain a pipe, the pipe comprising an inner surface and an outer surface, and perform argon arc welding on the pipe to weld the inner surface of the pipe; After rotating the pipe by a preset angle along the axial direction, pre-processing the pipe to form a groove on the outer surface of the pipe; Performing submerged arc welding on the outer surface of the pipe to fill the groove of the pipe with welding material; The pipe is heat treated to obtain a target metal pipe.

2. The method for preparing a metal pipe according to claim 1, characterized in that: The step of performing argon arc welding on the pipe to weld the inner surface of the pipe includes: The pipe is subjected to argon arc welding according to a first preset current and a first preset voltage to weld the inner surface of the pipe.

3. The method for preparing a metal pipe according to claim 2, characterized in that: The value range of the first preset current is greater than or equal to 350A and less than or equal to 400A; The value range of the first preset voltage is greater than or equal to 20 volts and less than or equal to 24 volts.

4. The method for preparing a metal pipe according to claim 1, characterized in that: The pre-processing of the pipe to form a groove on the outer surface of the pipe includes: Grinding the outer surface of the pipe; Spraying a nitric acid solution with a preset mass fraction on the polished outer surface at a preset spraying speed to mark a preset groove position on the outer surface; The outer surface is processed at the preset groove position to form the groove with a preset angle and a preset depth.

5. The method for preparing a metal pipe according to claim 4, characterized in that: The preset spraying speed has a value range of greater than or equal to 0.5 ml per minute and less than or equal to 0.8 ml per minute; The preset quality score has a value range of greater than or equal to 85% and less than or equal to 95%.

6. The method for preparing a metal pipe according to claim 4, characterized in that: The preset angle has a value range of greater than or equal to 30 degrees and less than or equal to 60 degrees; The preset depth has a value range of greater than or equal to 3 mm and less than or equal to 10 mm.

7. The method for preparing a metal pipe according to claim 4, characterized in that: Before processing the outer surface at the preset groove position to form the groove with a preset angle and a preset depth, the method further comprises: The two end faces of the pipe are subjected to sizing treatment.

8. The method for preparing a metal pipe according to any one of claims 1 to 7, characterized in that: Before obtaining the pipe, the method further includes: The inner surface of the tube is deburred.

9. The method for preparing a metal pipe according to claim 8, characterized in that: Before removing the burrs on the inner surface of the pipe, the method further includes: The plate is subjected to forming and welding processing to obtain the pipe.

10. The method for preparing a metal pipe according to claim 9, characterized in that: The components of the plate include at least carbon, silicon, manganese, nickel, chromium, molybdenum and iron.

11. The method for preparing a metal pipe according to claim 9, characterized in that: The forming and welding process is performed on the plate to obtain the pipe, comprising: The plate is subjected to roller forming by a center bending deformation method, and the radial weld of the formed plate rolled into a tube blank is subjected to high-frequency induction welding to obtain the tube.

12. The method for preparing a metal tube according to any one of claims 1 to 7, characterized in that: The submerged arc welding treatment is performed on the outer surface of the pipe to fill the welding material into the groove of the pipe, comprising: performing direct current welding on the pipe according to a second preset current and a second preset voltage, and The pipe is subjected to AC welding according to a third preset current and a third preset voltage to fill the groove of the pipe with welding material.

13. The method for preparing a metal pipe according to claim 12, characterized in that: The second preset current has a value range of greater than or equal to 800A and less than or equal to 1300A; The value range of the second preset voltage is greater than or equal to 30 volts and less than or equal to 33 volts.

14. The method for preparing a metal pipe according to claim 12, characterized in that: The third preset current has a value range of greater than or equal to 400A and less than or equal to 600A; The value range of the third preset voltage is greater than or equal to 32 volts and less than or equal to 35 volts.

15. The method for preparing a metal tube according to any one of claims 1 to 7, characterized in that: The step of heat treating the tube to obtain the target metal tube comprises: performing normalizing treatment at a first preset temperature on the plurality of pipes, and The tube after normalizing treatment is subjected to annealing treatment at a preset temperature drop rate to obtain the target metal tube.

16. The method for preparing a metal pipe according to claim 15, characterized in that: The preset temperature rise rate of the first preset temperature has a value range of greater than or equal to 50 degrees Celsius per second and less than or equal to 80 degrees Celsius per second.

17. The method for preparing a metal pipe according to claim 15, characterized in that: The value range of the first preset temperature is greater than or equal to 500 degrees Celsius and less than or equal to 1000 degrees Celsius.

18. The method for preparing a metal pipe according to claim 15, characterized in that: The preset temperature drop rate has a value range of greater than or equal to 3 degrees Celsius per second and less than or equal to 8 degrees Celsius per second.

19. A metal pipe, characterized in that: The metal pipe is made by the metal pipe preparation method according to any one of claims 1 to 18.

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