Manufacturing method of metal composite pipe and pipeline

Abstract

Compared with various existing metallurgical composite processes for manufacturing the metal composite pipe, the manufacturing method of the metal composite pipe has the advantages of being simple in process, low in cost, high in compatibility, high in safety, high in yield and the like. In addition, the invention further provides a pipeline for waste incineration equipment or oil and gas transmission equipment, and the pipeline is locally or completely constructed by using the metal composite pipe prepared by the manufacturing method of the metal composite pipe provided by the invention.

Description

Technical Field

[0001] The present invention belongs to the field of metal pipe manufacturing, and particularly relates to a manufacturing method and a pipeline of a metal composite pipe. Background Art

[0002] In the field of industrial production, especially in production scenarios with strongly corrosive media or harsh environmental conditions such as thermal combustion, chemical engineering, offshore engineering, oil and gas exploitation, etc., the pipeline systems in production equipment are exposed to composite corrosion factors such as acidic and alkaline media, high salt fog environment, or high temperature and high pressure for a long time. Pipes with traditional single-layer metal structures often suffer from wall thickness reduction, stress cracking, and even medium leakage due to surface corrosion, seriously threatening production safety and significantly increasing the pipeline maintenance frequency.

[0003] To improve production safety and reduce maintenance costs, metal composite pipes are often used in the prior art to construct pipeline systems in the above production scenarios. The metal composite pipe includes at least two layers, namely a base pipe layer and a corrosion-resistant layer. The base pipe layer is mainly used to provide rigidity, and the corrosion-resistant layer wraps the outer surface of the base pipe layer or covers the inner surface of the base pipe layer to provide corrosion-resistant protection for the base pipe layer. If both the inner and outer surfaces of the base pipe layer are covered with a corrosion-resistant layer, such pipes with corrosion-resistant treatment on both the inside and outside can cope with harsh working scenarios where there are corrosion factors both in the external environment and during internal transmission.

[0004] The forming processes of metal composite pipes can be divided into two categories: mechanical composite processes and metallurgical composite processes. For mechanical composite processes, it refers to forming a metal composite pipe by making the inner and outer layers of metal fit tightly through specific cold forming methods. Although its manufacturing cost is relatively low, the bonding strength between the two layers of metal is also low, and it is easy to delaminate and separate, so it is not suitable for making expansion parts and elbows. Therefore, to meet the production requirements in the production scenarios with strongly corrosive media or harsh environmental conditions mentioned above, metal composite pipes formed by mechanical composite processes are increasingly being replaced by metal composite pipes formed by metallurgical composite processes. For metallurgical composite processes, it refers to forming a metal composite pipe through hot processing methods, forming atomic diffusion at the interface between the base pipe and the outer sleeve pipe / liner pipe, so that the outside of the base pipe is tightly wrapped by the outer sleeve pipe, or the inner cavity of the base pipe is tightly combined with the liner pipe, and the outer sleeve pipe / liner pipe corresponds to the corrosion-resistant layer mentioned above.

[0005] Traditional various metallurgical composite processes each have different disadvantages. For example, in the hot rolling forming method, the combination of most easily oxidized ferrous metal materials cannot be achieved by rolling; in the hot extrusion composite method, the formed surface is rough, the wall thickness uniformity at the pipe end is poor, and since the bonding effect depends on the elemental interface diffusion within an extremely short time during the extrusion process, it is usually affected by the presence of an oxide film, and the problem of interface stress concentration is difficult to overcome; in the centrifugal casting combined with hot extrusion method, the metal combination is limited, slag inclusions between layers are likely to appear, and the wall thickness uniformity at the pipe end is relatively poor; in the centrifugal aluminothermic method, without subsequent hot deformation, it is only limited to use in the as-cast state, the control of the clad layer composition is difficult, and the coarse as-cast structure of the clad layer results in the mechanical properties of the clad layer metal not being fully exerted; in the explosion welding forming method, its productivity is low and the production process is highly dangerous; in the surfacing (cladding) composite method, the production cost is high, the process is complex, and the material combinations of the pipes that can be produced have compatibility limitations.

[0006] Therefore, how to provide a manufacturing process for metal composite pipes that can meet the expectations in multiple aspects such as manufacturing cost, production efficiency, and the strength of the pipe finished products is a technical difficulty at the present stage. Summary of the Invention

[0007] In order to overcome the above defects in the prior art, the present invention provides a manufacturing method for metal composite pipes, which includes:

[0008] Providing a first pipe and a second pipe, both the first pipe and the second pipe are made of metal, the first pipe has a first surface, and the second pipe has a second surface;

[0009] Attaching alloy powder to the first surface or the second surface to form an alloy layer covering the first surface or the second surface;

[0010] Coaxially sleeving the first pipe and the second pipe, making the first surface face the second surface, and making the alloy layer be between the first surface and the second surface to form a multi-layer pipe;

[0011] Performing a pressing and composite treatment on the multi-layer pipe to make the first pipe and the second pipe form an interference fit;

[0012] Performing a heating treatment on the multi-layer pipe to make the temperature of the alloy layer reach its remelting temperature;

[0013] Performing a cooling treatment on the multi-layer pipe to obtain a metal composite pipe, in which the alloy layer in the metal composite pipe forms a metallurgical bond with the first surface and the second surface respectively, and the first pipe forms an interface bond with the second pipe through the alloy layer.

[0014] According to one aspect of the present invention, in the manufacturing method, the step of heating the multi-layer tube includes: placing the multi-layer tube in a heating furnace and heating the multi-layer tube as a whole; or sequentially transporting multiple sections of the multi-layer tube into the heating furnace along a predetermined feeding direction for segmented heating.

[0015] According to another aspect of the present invention, in the manufacturing method, the step of overall heating or segmented heating includes: controlling the power of the heating furnace so that the temperature of the heated section of the multi-layer tube located inside the heating furnace increases in a gradient manner.

[0016] According to another aspect of the present invention, in the manufacturing method, the gradient increase includes the following stages: the first stage, continuously heating the heated section to make the temperature of the heated section reach a first temperature; the second stage, continuing to heat the heated section to make the temperature of the heated section reach a second temperature; the third stage, continuing to heat the heated section to make the temperature of the heated section reach the remelting temperature.

[0017] According to another aspect of the present invention, in the manufacturing method, the first temperature is not higher than 750 °C; the second temperature is greater than the first temperature and less than the remelting temperature.

[0018] According to another aspect of the present invention, in the manufacturing method, when overall heating or segmented heating the multi-layer tube, the multi-layer tube rotates around its central axis, and / or the induction coil group of the heating furnace rotates around the multi-layer tube.

[0019] According to another aspect of the present invention, in the manufacturing method, when overall heating or segmented heating the multi-layer tube, a pressing force is applied outside the multi-layer tube.

[0020] According to another aspect of the present invention, in the manufacturing method, when overall heating or segmented heating the multi-layer tube, the inner cavity of the multi-layer tube is sealed, and a protective gas is injected into the inner cavity so that the air pressure value in the inner cavity is not lower than a predetermined threshold.

[0021] According to another aspect of the present invention, in the manufacturing method, the range of the predetermined threshold is 0.1 Mpa to 10 Mpa.

[0022] According to another aspect of the present invention, in the manufacturing method, the step of cooling the multi-layer tube includes: arranging a spray device or an air-cooling device at the discharge port of the multi-layer tube to cool the multi-layer tube.

[0023] According to another aspect of the present invention, after the cooling treatment, the manufacturing method further includes: performing a tempering treatment on the metal composite tube.

[0024] According to another aspect of the present invention, before attaching the alloy powder, the manufacturing method further includes roughening the surface of the first surface or the second surface that bears the alloy powder.

[0025] According to another aspect of the present invention, in the manufacturing method, the melting point of the alloy layer is lower than the melting points of the first pipe and the second pipe; the thickness range of the alloy layer is from 0.01 mm to 0.5 mm, and the thicknesses of the first pipe and the second pipe are at least twice the thickness of the alloy layer.

[0026] According to another aspect of the present invention, in the manufacturing method, the first pipe is sleeved outside the second pipe, the first surface is the inner surface of the first pipe, and the second surface is the outer surface of the second pipe; the alloy powder is sprayed on the first surface or the second surface.

[0027] According to another aspect of the present invention, in the manufacturing method, the step of compacting and compounding the multi-layer pipe includes sealing the cavity formed by enclosing the inner surface of the second pipe and injecting a pressurizing medium into the cavity to cause the second pipe to undergo plastic expansion deformation and then closely adhere to the first pipe; the material of the first pipe includes any one or all of carbon steel and iron-based alloys; the material of the second pipe includes any one, any combination or all of alloy steel, 316L stainless steel, nickel-based alloy, cobalt-based alloy and titanium alloy; the material of the alloy layer includes any one, any combination or all of nickel-based alloy, cobalt-based alloy or iron-based alloy doped with boron and / or silicon.

[0028] According to another aspect of the present invention, in the manufacturing method, the second pipe is sleeved outside the first pipe, the first surface is the outer surface of the first pipe, and the second surface is the inner surface of the second pipe; the alloy powder is sprayed on the first surface or the second surface.

[0029] According to another aspect of the present invention, in the manufacturing method, the step of compacting and compounding the multi-layer pipe includes arranging a mandrel in the cavity formed by enclosing the inner surface of the first pipe and applying a radial pressure on the outer surface of the second pipe to cause the second pipe to undergo plastic reduction deformation and then closely adhere to the first pipe; the material of the first pipe includes any one or all of carbon steel and iron-based alloys; the material of the second pipe includes any one, any combination or all of alloy steel, 316L stainless steel, nickel-based alloy, cobalt-based alloy and titanium alloy; the material of the alloy layer includes any one, any combination or all of nickel-based alloy, cobalt-based alloy or iron-based alloy doped with boron and / or silicon.

[0030] In addition, the present invention also provides a pipeline for a waste incineration device or an oil and gas transmission device, and a part or all of the pipeline is constructed using a metal composite pipe prepared by the manufacturing method described above.

[0031] The manufacturing method of the metal composite pipe provided by the present invention forms a metallurgical bond between the alloy layer and the first pipe and the second pipe respectively by setting an alloy layer between the first pipe and the second pipe and remelting it, so that the first pipe forms an interfacial bond with the second pipe through the alloy layer. The metal composite pipe thus manufactured can meet the performance consistency requirements in multiple aspects such as different pipe diameters, different length positions, and different angles. Due to the high strength of the metallurgical bond, the first pipe and the second pipe have sufficient interfacial bond strength. Even if subsequent plastic deformation machining processes such as pipe bending and diameter reduction are performed on the metal composite pipe, it is difficult for the layers of the metal composite pipe to separate. Compared with various existing metallurgical composite processes for manufacturing metal composite pipes, the manufacturing method of the metal composite pipe provided by the present invention has the advantages of simple process, low cost, strong compatibility, high safety, and high yield rate respectively. Brief Description of the Drawings

[0032] Other features, objects, and advantages of the present invention will become more apparent by reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0033] Figure 1 is a schematic flowchart of a specific embodiment of the manufacturing method of the metal composite pipe according to the present invention;

[0034] Figure 2 is according to Figure 1 is a schematic cross-sectional structure diagram of an optional embodiment of the inner anti-corrosion metal composite pipe prepared by the manufacturing method;

[0035] Figure 3 is Figure 1 is a schematic scenario diagram of an optional embodiment of step S200 shown;

[0036] Figure 4 is Figure 1 is a schematic scenario diagram of another optional embodiment of step S200 shown;

[0037] Figure 5 is Figure 1 is a schematic scenario diagram of an optional embodiment of step S300 shown;

[0038] Figure 6 is Figure 1 is a schematic scenario diagram of an optional embodiment of step S400 shown;

[0039] Figure 7 isFigure 1 A schematic diagram of a scenario of a preferred embodiment of the pressing composite process described in step S400 shown;

[0040] Figure 8 is Figure 1 A schematic diagram of a scenario of an alternative embodiment of steps S500 and S600 shown;

[0041] Figure 9 is according to Figure 1 A schematic cross-sectional structure diagram of an alternative embodiment of an externally anti-corrosion metal composite pipe prepared by the manufacturing method shown;

[0042] Figure 10 is Figure 1 A schematic diagram of a scenario of another alternative embodiment of step S400 shown;

[0043] Figure 11 is Figure 1 A schematic diagram of a scenario of another preferred embodiment of step S400 shown

[0044] Like or similar reference numerals in the drawings represent like or similar components. Detailed Description of the Invention

[0045] In order to better understand and explain the present invention, the present invention will be further described in detail below with reference to the drawings. The present invention is not limited solely to these specific embodiments. On the contrary, modifications or equivalent replacements made to the present invention shall be covered within the scope of the claims of the present invention.

[0046] It should be noted that numerous specific details are given in the following detailed description. Those skilled in the art should understand that the present invention can be implemented without these specific details. In the following multiple detailed embodiments, well-known structures and components are not described in detail in order to highlight the gist of the present invention.

[0047] In the present invention, unless otherwise clearly specified and defined, the first feature being “on” or “under” the second feature may include direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but are in contact through additional features therebetween. Moreover, the first feature being “above”, “over” and “on top of” the second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature has a higher horizontal height than the second feature. The first feature being “under”, “beneath” and “underneath” the second feature includes the first feature being directly below and obliquely below the second feature, or simply indicating that the first feature has a lower horizontal height than the second feature.

[0048] In the description of this embodiment, the orientation or positional relationships such as "upper", "lower", "right", etc. are based on the orientation or positional relationships shown in the drawings. They are only for the convenience of description and simplifying the operations, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. In addition, the terms "first" and "second" are only used for differentiation in description and have no special meanings.

[0049] The following will describe each specific embodiment of the present invention with reference to the accompanying drawings of the specification. It should be noted that each drawing of the specification is only used to schematically illustrate the technical solution and core concept of the present invention. The shapes and sizes of the components of each specific embodiment shown in each drawing of the specification are not drawn strictly in accordance with the form of the actual product. There may be differences between the shape, size ratio of the actual product and those shown in each specific embodiment of the drawings of the specification. Therefore, the specific embodiments shown in the drawings should not be construed as the only limitation to the corresponding actual product of the present invention, nor can it be used as the only basis for comparing the shapes and sizes in determining patent infringement.

[0050] Please refer to Figure 1 , Figure 1 which is a schematic flow chart of a specific embodiment of the manufacturing method of the metal composite pipe according to the present invention. As Figure 1 shown, a manufacturing method of a metal composite pipe provided by the present invention includes the following steps:

[0051] Step S100: Provide a first pipe and a second pipe. Both the first pipe and the second pipe are made of metal. The first pipe has a first surface, and the second pipe has a second surface.

[0052] Step S200: Attach alloy powder to the first surface or the second surface to form an alloy layer covering the first surface or the second surface.

[0053] Step S300: Coaxially sleeve the first pipe and the second pipe, make the first surface face the second surface, and make the alloy layer be between the first surface and the second surface to form a multi-layer pipe.

[0054] Step S400: Perform a pressing and composite treatment on the multi-layer pipe to make the first pipe and the second pipe form an interference fit.

[0055] Step S500: Perform a heating treatment on the multi-layer pipe to make the temperature of the alloy layer reach its remelting temperature.

[0056] Step S600, cooling the multi-layer tube to obtain a metal composite tube, wherein the alloy layers in the metal composite tube are metallurgically bonded to the first surface and the second surface respectively, and the first pipe and the second pipe are interfacially bonded through the alloy layer.

[0057] Specifically, one of the objects of the present invention is to provide a manufacturing method of a metal composite tube. The metal composite tube obtained by this manufacturing method has at least a corrosion-resistant layer and a base tube layer made of metal materials, and there is sufficient interfacial bonding strength between the corrosion-resistant layer and the base tube layer, so that when the metal composite tube performs subsequent plastic deformation machining processes, it is not easy to delaminate due to insufficient internal interfacial bonding strength. Generally, the corrosion-resistant layer has a thinner thickness and better ductility than the base tube layer.

[0058] Execute Figure 1 By performing the steps S100 to S600 shown, two different types of the metal composite tubes can be obtained, namely an internally corrosion-resistant metal composite tube and an externally corrosion-resistant metal composite tube. For the internally corrosion-resistant metal composite tube whose typical application scenario is the closed transportation of strongly corrosive media (such as high-temperature flue gas discharge, oil and gas transportation, transportation of strongly oxidizing media, etc.), obviously the substances causing corrosion to it mainly exist inside the internally corrosion-resistant metal composite tube. Correspondingly, the internally corrosion-resistant metal composite tube needs to have the corrosion-resistant function of its inner cavity, that is, the corrosion-resistant layer should be formed on the inner wall of the base tube layer; for the externally corrosion-resistant metal composite tube whose typical application scenario is to close the transportation of neutral media under working conditions where there are many corrosion factors in the external environment (such as deep-sea oil and gas transportation pipelines, underwater cooling pipes, fluidized bed walls, garbage incineration combustion chamber walls, etc.), obviously the substances causing corrosion to it mainly exist outside the externally corrosion-resistant metal composite tube. Correspondingly, the externally corrosion-resistant metal composite tube needs to have the corrosion-resistant function of its outer surface, that is, the corrosion-resistant layer should be formed on the outer wall of the base tube layer.

[0059] In step S100, the second pipe can be selected to correspond to the corrosion-resistant layer, and correspondingly, the first pipe can be selected to correspond to the base tube layer. The alloy layer in step S200 can be formed on the base tube layer or on the corrosion-resistant layer. Preferably, the alloy layer can be formed by spraying the alloy powder on the target plane using a powder spraying process. The powder spraying process includes but is not limited to electrostatic spraying process, thermosetting spraying process, and fluidized bed dipping process.

[0060] Taking the case where the second pipe is selected to correspond to the corrosion-resistant layer and the manufacturing target is to obtain the internally corrosion-resistant metal composite tube as an example, Figure 1 the steps in the specific implementation shown will be described. Please refer to Figure 2 ,Figure 2 is according to Figure 1 FIG. is a schematic cross-sectional structure diagram of an alternative embodiment of an internally anti-corrosion metal composite pipe prepared by the shown manufacturing method, as Figure 2 shown, the internally anti-corrosion metal composite pipe 101 includes a first pipe 110, a second pipe 120 and an alloy layer 130, wherein the alloy layer 130 forms a metallurgical bond with the first pipe 110 and the second pipe 120 respectively, the first pipe 110 forms an interfacial bond with the second pipe 120 through the alloy layer 130, the first pipe 110 is sleeved outside the second pipe 120, and the first pipe 110 and the second pipe 120 can be seamless pipes or welded pipes formed by rolling and welding sheet materials.

[0061] Please refer to Figure 3 , Figure 3 is Figure 1 a schematic scenario diagram of an alternative embodiment of step S200 shown, as Figure 3 shown, when choosing to use an electrostatic spraying process or a thermosetting spraying process to form the alloy layer 130, if the diameter of the first pipe 110 is large enough to accommodate the spray head 201 to extend into the interior of the first pipe 110 for powder spraying operation, then in step S200, it can be considered to spray the alloy powder on the first surface 111 of the first pipe 110, that is, to form the alloy layer 130 covering the first surface 111. At this time, the first surface 111 is the inner surface of the first pipe 110.

[0062] Please refer to Figure 4 , Figure 4 is Figure 1 a schematic scenario diagram of another alternative embodiment of step S200 shown, as Figure 4 shown, when choosing to use an electrostatic spraying process or a thermosetting spraying process to form the alloy layer 130, if the diameter of the first pipe 110 is small and not enough to accommodate the spray head 201 to enter the interior of the first pipe 110 for powder spraying operation, then in step S200, it can be considered to spray the alloy powder on the second surface 121 of the second pipe 120, that is, to form the alloy layer 130 covering the second surface 121. At this time, the second surface 121 is the outer surface of the second pipe 120.

[0063] Typically, in order to enable the alloy powder to better adhere to the first surface 111 or the second surface 121, before adhering the alloy powder, it can be considered to roughen the first surface 111 or the second surface 121. Since both the first pipe 110 and the second pipe 120 are made of metal materials, the roughening treatment preferably adopts a sandblasting process or a shot peening process.

[0064] Regardless of whether step S200 is implemented as adopting the Figure 3 embodiment shown or adopting the Figure 4In the illustrated embodiments, after the alloy layer 130 is formed, in step S300, the first pipe 110 and the second pipe 120 need to be coaxially sleeved. More specifically, the first pipe 110 is sleeved outside the second pipe 120. Please refer to Figure 5 , Figure 5 is Figure 1 a schematic diagram of a scenario of an alternative embodiment of step S300 shown in the figure. As Figure 5 shown, after the first pipe 110 and the second pipe 120 are coaxially sleeved, a multi-layer pipe 102 is formed, wherein the inner surface of the first pipe 110 faces the outer surface of the second pipe 120, and the alloy layer 130 is between the inner surface of the first pipe 110 and the outer surface of the second pipe 120.

[0065] Next, step S400 is executed to perform a pressing and compounding process on the multi-layer pipe 102 to make the first pipe 110 and the second pipe 120 form an interference fit. One purpose of executing step S400 is: through the interference fit, the first pipe 110, the alloy layer 130, and the second pipe 120 are closely fitted together, and the first pipe 110 and the second pipe 120 exert pressure on the alloy layer 130 to obtain an alloy layer 130 with a substantially uniform thickness, and as much oxygen as possible between the first pipe 110 and the alloy layer 130, or between the second pipe and the alloy layer 130 is discharged, which helps to improve the temperature consistency of the alloy layer 130 when the multi-layer pipe 102 is heated in step S500, and can also avoid the generation of oxide scale to ensure the remelting effect of the alloy layer 130. Another purpose of executing step S400 is: through the interference fit, the manufacturing deviation of the second pipe 120 is corrected, so that the first pipe 110 and the second pipe 120 can achieve a coaxial sleeve setting that meets the requirements, and the situation of eccentric sleeve setting of the first pipe 110 and the second pipe 120 is avoided, which affects the final yield.

[0066] Please refer to Figure 6 , Figure 6 is Figure 1 a schematic diagram of a scenario of an alternative embodiment of step S400 shown in the figure. As Figure 4 and Figure 6As shown, in step S200, it is selected to form the alloy layer 130 on the outer surface (i.e., the second surface 121) of the second pipe fitting 120. After the first pipe fitting 110 is sleeved outside the second pipe fitting 120 in step S300, it is possible that the outer diameter of the second pipe fitting 120 is still smaller than the inner diameter of the first pipe fitting 110, which results in a gap 140 between the first pipe fitting 110 and the second pipe fitting 120 in the multi-layer pipe 102. Therefore, it is necessary to perform a pressing and compounding process on the multi-layer pipe 102 to obtain a multi-layer pipe 102 with tight fitting between each layer. The preferred method for the pressing and compounding process is to plastically expand the diameter of the second pipe fitting 120, and the preferred method for the plastic diameter expansion is hydraulic diameter expansion. The specific steps include: sealing the cavity formed by enclosing the inner surface of the second pipe 120, and injecting a pressurized medium into the cavity to cause the second pipe 120 to undergo plastic diameter expansion deformation and then closely adhere to the first pipe 110. Please refer to Figure 7 , Figure 7 is Figure 1 a schematic diagram of a scenario of a preferred embodiment of the pressing and compounding process described in step S400 shown in the figure. As Figure 7 shown, end heads 202 are provided at both ends of the multi-layer pipe 102 to seal the inner cavity of the second pipe 120. A pressurized medium delivery pipe 203 penetrating through the end head 202 is provided on one of the end heads 202. By injecting a pressurized medium into the inner cavity, water or hydraulic oil can be used as the pressurized medium. The injected pressurized medium increases the pressure in the inner cavity, and the second pipe 120 undergoes plastic deformation under pressure, and its diameter increases, so that the alloy layer 130 formed on the outer surface of the second pipe 120 closely adheres to the inner surface of the first pipe 110. Due to the tensioning effect of the second pipe 120, the first pipe 110 also undergoes elastic deformation. When the pressure in the inner cavity is relieved, the first pipe 110 undergoes shrinkage and rebound and tightly wraps the second pipe 120 that has undergone plastic diameter expansion deformation. More preferably, the pressurized medium delivery pipe 203 is connected to an external pressure control system, and the pressure control system can control the upper limit of the pressure in the inner cavity so that the first pipe 110 only undergoes elastic deformation without undergoing plastic deformation. In other embodiments, the plastic diameter expansion can also be achieved using a cross-rolling diameter expander.

[0067] Further, in step S500, the multi-layer tube 102 is heat-treated to bring the temperature of the alloy layer 130 to the remelting temperature. During the heat treatment, the ideal state is that the entire alloy layer 130 can reach the remelting temperature controllably and uniformly, while the self-strength, surface properties, etc. of the first pipe 110 and the second pipe 120 are not damaged. That is, it is desired that when the temperature of the alloy layer 130 is heated to the remelting temperature, the temperatures of the first pipe 110 and the second pipe 120 have not reached their corresponding melting points. Therefore, it is preferably selected that the melting point of the alloy layer 130 is lower than the melting points of the first pipe 110 and the second pipe 120. If the melting point of the alloy layer 130 is greater than the melting points of the first pipe 110 and the second pipe 120, the first pipe 110 and the second pipe 120 will be melted before the alloy layer 130 forms a metallurgical bond with the first pipe 110 and the second pipe 120. Subsequently, during the process of re-cooling, the first pipe 110 and the second pipe 120 may become embrittled, resulting in cracks, and there may also be adverse effects such as pores, coarse grains, and stress accumulation inside, thereby causing the first pipe 110 and the second pipe 120 to lose their toughness and strength.

[0068] In most cases, considering the manufacturing cost, the first pipe 110 and the second pipe 120 are usually made of different materials. For example, in this embodiment, the second pipe 120 is selected to correspond to the corrosion-resistant layer, and the first pipe 110 is selected to correspond to the base pipe layer. The second pipe 120 can be made of a material with a higher cost to resist chemical corrosion, impact corrosion, etc. of the medium conveyed inside it. The first pipe can be made of a material with a lower cost, mainly used to provide the mechanical properties of the metal composite pipe to resist tensile force, pressure, impact force, etc. applied inside and outside the metal composite pipe. Of course, no matter how the materials of the first pipe 110 and the second pipe 120 are selected, it is preferred that the melting point of the alloy layer 130 is lower than the melting points of the first pipe 110 and the second pipe 120. Adjusting the melting point of the alloy layer 130 can be achieved by reasonably proportioning the proportions of various materials in the alloy powder. For example, the alloy powder is prepared by adding boron or silicon elements to the metal alloy. Preferably, in this embodiment, the material of the first pipe 110 includes any one or all of carbon steel and iron-based alloys; the material of the second pipe 120 includes any one, any combination, or all of alloy steel, 316L stainless steel, nickel-based alloy, cobalt-based alloy, and titanium alloy; the material of the alloy layer 130 includes any one, any combination, or all of nickel-based alloy, cobalt-based alloy, or iron-based alloy doped with boron and / or silicon. The implementer of this embodiment can select the material of the second pipe 120 according to the type of corrosive medium. For example, austenitic stainless steel (such as 316L stainless steel) is selected to deal with the case where the corrosion type is salt spray corrosion, duplex stainless steel is selected to deal with the case where the corrosion type is erosion corrosion and chloride ion corrosion, Hastelloy in nickel-based alloy is selected to deal with the case where the corrosion type is high-temperature flue gas corrosion, acidic gas corrosion, and boiling strong acid, TA2 titanium alloy is selected to deal with the case where the corrosion type is brine corrosion and chloride ion stress corrosion, and cobalt-based alloy Stellite is selected to deal with the case where the chemical corrosion type and the erosion corrosion type coexist, etc. Therefore, the material selection of the second pipe 120 is highly related to the working scenario of the internal anti-corrosion metal composite pipe 101 and can be flexibly selected according to the actual situation. The present invention does not limit this.

[0069] From the perspective of material conservation, through repeated experiments for verification, when the thickness range of the alloy layer 130 is from 0.01 mm to 0.5 mm, it can meet the requirement that the alloy layer 130 can stably and controllably form a metallurgical bond with the first pipe 110 and the second pipe 120 respectively, and finally enable the first pipe 110 to form a metallurgical bond with sufficient strength with the second pipe 120 through the alloy layer 130. At the same time, further experimental verification shows that when the thickness of the first pipe 110 and the second pipe 120 is set to be at least twice the thickness of the alloy layer 130, since the first pipe 110 and the second pipe 120 have sufficient thickness, even if there is a slight deviation in temperature control or heating duration during the remelting process of the alloy layer 130, it is not easy for the components of the alloy layer 130 to diffuse excessively into the first pipe 110 and the second pipe 120. Such excessive diffusion may cause the overall or local element ratio imbalance, metallographic deterioration, etc. of the first pipe 110 and the second pipe 120. For example, the diffusion of boron or silicon may lead to grain boundary brittleness or element segregation, thereby degrading the overall performance of the first pipe 110 and the second pipe 120. Preferably, the thickness range of the first pipe 110 is from 3 mm to 20 mm, and the thickness of the second pipe 120 is from 1 mm to 3 mm.

[0070] As described above, when performing the heating treatment in step S500 on the multi-layer pipe 102, the most ideal state is that the entire alloy layer 130 can reach the remelting temperature controllably and uniformly. Typically, the steps of heating the multi-layer pipe 102 include: placing the multi-layer pipe 102 in a heating furnace and heating the multi-layer pipe 102 as a whole; or along a predetermined feeding direction, sequentially transporting multiple sections of the multi-layer pipe 102 into the heating furnace for sectional heating. Among them, the overall heating is applicable to the case where the axial length of the multi-layer pipe 102 is relatively short. For the case where the axial length of the multi-layer pipe 102 is relatively long, the sectional heating is obviously more suitable. The sectional heating can be achieved by arranging multiple heating furnaces on the feeding path of the multi-layer pipe 102, or by discretely feeding the multi-layer pipe 102 into a heating furnace section by section in time for heating. Through experiments, it is found that whether it is the overall heating or the sectional heating, making the temperature change of the heated section of the multi-layer pipe 102 located in the heating furnace increase in a gradient manner is helpful to improve the remelting effect of the alloy layer 130.

[0071] Preferably, the gradient increase includes the following stages: the first stage, continuously heating the heated section to make the temperature of the heated section reach the first temperature; the second stage, continuing to heat the heated section to make the temperature of the heated section reach the second temperature; the third stage, continuing to heat the heated section to make the temperature of the heated section reach the remelting temperature.

[0072] According to the specific material selection of the first pipe 110, the second pipe 120, and the alloy layer 130 listed in this embodiment, the melting point of the first pipe 110 is the same as or close to the melting point of elemental iron, that is, not higher than 1538 °C. The melting point of the second pipe 120 generally falls within the range of 1290 °C to 1450 °C. The melting point of the alloy layer 130 is preferably adjusted to fall within the range of 850 °C to 1100 °C. Correspondingly, the first temperature is not higher than 750 °C, the second temperature is greater than the first temperature and less than the remelting temperature.

[0073] Preferably, in order to improve the temperature uniformity of the heated section, after the temperature of the heated section reaches a preset temperature, it can be subjected to constant temperature and heat preservation treatment. Preferably, in the first stage, when the temperature of the heated section reaches the first temperature, the heated section is heat-preserved for a first duration; in the second stage, when the temperature of the heated section reaches the second temperature, the heated section is heat-preserved for a second duration; in the third stage, when the temperature of the heated section reaches the remelting temperature, the heated section is heat-preserved for a third duration. The first duration, the second duration, and the third duration preferably do not exceed 600 seconds. It should be specifically noted that the constant temperature and heat preservation treatment can be achieved by periodically placing the heated section in the heating furnace so that the heated section continuously remains in the heating furnace and is maintained at a constant temperature. However, this is not the only method for the constant temperature and heat preservation treatment. On the contrary, the multi-layer pipe 102 can move along a predetermined feeding direction under the drive of equipment such as feeding wheels and feeding rollers on the production line. By reasonably setting the movement speed of the multi-layer pipe 102, the residence time of the heated section in the heating furnace can be regarded as the heat preservation time of the heated section while the heated section is heated to the first temperature, the second temperature, or the remelting temperature in the heating furnace.

[0074] Based on the consideration of precise control of the heating temperature, the heating furnace can be realized by using an intermediate frequency induction heating furnace. The intermediate frequency induction heating furnace includes one or more heating coils, and a thermometer is arranged on each heating coil for real-time monitoring and feedback of temperature information. The working current frequency of the heating coil is preferably set within the range of 500 Hz to 12000 Hz.

[0075] To avoid delamination between the alloy layer 130 and the first pipe 110 during the heating of the multi-layer pipe 102, preferably, when performing the overall heating or the segmented heating on the multi-layer pipe 102, a pressing force can be applied to the outside of the multi-layer pipe 102. For example, a suitable set of pressing rollers can be used to force the first pipe 110 to undergo a non-plastic diameter reduction deformation, so that the first pipe 110 and the alloy layer 130 can be more closely fitted, and it is also easier for the alloy layer 130 to form a metallurgical bond with the first pipe 110.

[0076] Please refer to Figure 8 , Figure 8 is Figure 1 a schematic diagram of a scenario of an alternative embodiment of step S500 and step S600 shown, as Figure 8 shown, the multi-layer pipe 102 is sent into the heating furnace 205 for the overall heating or the segmented heating. At this time, the induction coil group of the heating furnace 205 is fixed, and the multi-layer pipe 102 rotates around its central axis, which helps the multi-layer pipe 102 to be evenly heated in the heating furnace 205. In other embodiments, the induction coil group of the heating furnace 205 can be set to rotate around the multi-layer pipe 102, and the multi-layer pipe 102 can also be made to rotate around its central axis at the same time, which also helps the multi-layer pipe 102 to be evenly heated.

[0077] Since the first pipe 110 and the second pipe 120 are usually made of different metal materials, they often have different coefficients of thermal expansion. During the process of the overall heating or the segmented heating, delamination between the first pipe 110 and the second pipe 120 often occurs. Especially for some special dimensions of the diameters and wall thicknesses of the first pipe 110 and the second pipe 120, this delamination phenomenon is more obvious. And the delamination phenomenon will make it difficult for the interfacial bonding strength between the first pipe 110 and the second pipe 120 to reach the expected value. It has been found through experiments that when the multi-layer pipe 102 is subjected to the overall heating or the segmented heating, if the inner cavity of the sealed multi-layer pipe 102 is filled with a protective gas (preferably an inert gas) such that the air pressure value in the inner cavity is not lower than a predetermined threshold, the occurrence frequency of the delamination phenomenon can be greatly reduced. During the heating process of the multi-layer pipe 102, the protective gas in the inner cavity expands simultaneously when heated, which can force the second pipe 120 to produce an elastic diameter-expanding deformation, causing the second pipe 120 to push the alloy layer 130 closer to the inner surface of the first pipe 110. Especially after the alloy layer 130 reaches its remelting temperature, the liquid alloy layer 130 can fully contact the first pipe 110 and the second pipe 120 under the expansion and extrusion action of the protective gas, and form a higher-quality metallurgical bond with both the first pipe 110 and the second pipe 120 respectively. In addition, when the protective gas is preferably an inert gas, the generation of oxide scale on the inner surface of the second pipe 120 can also be reduced. If the air pressure value in the inner cavity is too low, the effect of generating enough pressure to force the second pipe 120 to produce an elastic diameter-expanding deformation cannot be achieved. If the air pressure value in the inner cavity is too high, there is also a certain degree of danger. Tests have found that the optimal solution is when the range of the predetermined threshold falls within the range of 0.1 Mpa to 10 Mpa.

[0078] In step S600, the heated multi-layer pipe 102 is cooled to obtain the inner-corrosion-resistant metal composite pipe 101 as Figure 2 shown. Preferably, as Figure 8 shown, the steps of cooling the multi-layer pipe 102 include: a rapid cooling device 206 is arranged at the discharge port of the multi-layer pipe 102 to cool the multi-layer pipe 102. The rapid cooling device 206 is typically a spray device using water as the cooling medium or an air-cooling device using gas as the cooling medium. In other embodiments, the multi-layer pipe 102 can also be cooled by natural placement cooling.

[0079] Preferably, in order to refine the grains and eliminate the internal stress, thereby improving the performance of the inner-corrosion-resistant metal composite pipe 101, after the cooling treatment in step S600, the following preferred steps can also be performed: tempering the inner-corrosion-resistant metal composite pipe 101.

[0080] The internal corrosion-resistant metal composite pipe 101 prepared by implementing the respective embodiments of steps S100 to S600 has sufficient bonding strength between the first pipe 110 and the second pipe 120. This bonding strength can approach the shear strength of the first pipe 110 and the second pipe 120, usually above 300 Mpa, and can reach up to about 450 Mpa at most.

[0081] The above Figures 2 to 8 The specific implementation manners of the combination formed in the respective embodiments shown are described for steps S100 to S600 on the premise of selecting the second pipe 120 corresponding to the corrosion-resistant layer and the manufacturing target is to obtain the internal corrosion-resistant metal composite pipe 101 as Figure 2 shown. If the manufacturing target is to obtain the external corrosion-resistant metal composite pipe as described above, compared with Figures 2 to 8 the specific implementation manners of the combination formed in the respective embodiments shown, some technical details in steps S100 to S600 are different and need to be adjusted according to the structural characteristic that the corrosion-resistant layer in the external corrosion-resistant metal composite pipe is formed on the outside of the base pipe layer.

[0082] Please refer to Figure 9 , Figure 9 which is Figure 1 a schematic cross-sectional structure diagram of an alternative embodiment of the external corrosion-resistant metal composite pipe prepared by the manufacturing method shown. As Figure 9 shown, the external corrosion-resistant metal composite pipe 103 includes a first pipe 110, a second pipe 120, and an alloy layer 130. The alloy layer 130 forms a metallurgical bond with the first pipe 110 and the second pipe 120 respectively. The first pipe 110 forms an interfacial bond with the second pipe 120 through the alloy layer 130. The second pipe 120 is sleeved outside the first pipe 110. The first pipe 110 and the second pipe 120 can be seamless pipes or welded pipes made by rolling and welding sheet materials.

[0083] According to Figure 9 the embodiment shown, select the second pipe 120 corresponding to the corrosion-resistant layer of the external corrosion-resistant metal composite pipe 103 and the first pipe 110 corresponding to the base pipe layer of the external corrosion-resistant metal composite pipe 103, and on this premise, steps S100 to S600 are described.

[0084] When forming the alloy layer 130 in step S200, referring to the explanations of the two alternative embodiments of S200 in the foregoing text, it is only necessary to form the alloy layer 130 between the first pipe fitting 110 and the second pipe fitting 120. Correspondingly, when choosing to use the electrostatic spraying process or the thermosetting spraying process to form the alloy layer 130, if the diameter of the second pipe fitting 120 is small, the alloy layer 130 can be formed on the outer surface of the first pipe fitting 110 (corresponding to the first surface of the first pipe fitting 110); if the diameter of the second pipe fitting 120 is large, the alloy layer 130 can be formed on the inner surface of the second pipe fitting 120 (corresponding to the second surface of the second pipe fitting 120).

[0085] Correspondingly, before forming the alloy layer 130, preferably perform roughening treatment on the outer surface of the first pipe fitting 110 or the inner surface of the second pipe fitting 120 according to the formation position of the alloy layer 130.

[0086] After step S200 is executed, in step S300, the first pipe 110 and the second pipe 120 are coaxially sleeved. More specifically, the second pipe 120 is sleeved outside the first pipe 110 to form a multi-layer pipe 104 as shown in Figure 10 Please refer to Figure 10 , Figure 10 is Figure 1 a schematic diagram of a scene of another alternative embodiment of step S300 shown in. As in the multi-layer pipe 104 shown in Figure 10 , since the second pipe 120 corresponds to the corrosion-resistant layer of the external anti-corrosion metal composite pipe 103 and the first pipe 110 corresponds to the base pipe layer of the external anti-corrosion metal composite pipe 103, usually the second pipe 120 will have a thinner thickness and better ductility than the first pipe 110. Therefore, when performing the pressing and compounding treatment on the multi-layer pipe 104 in step S400, generally the embodiments shown in Figure 6 and Figure 7 will not be considered, that is, the method of plastically expanding the diameter of the first pipe 110 will not be considered to achieve the pressing and compounding treatment in step S300. Instead, consideration should be given to how to make the second pipe 120 undergo plastic diameter reduction deformation and then closely adhere to the outer surface of the first pipe 110. Therefore, preferably, the steps of the pressing and compounding treatment in step S300 include: setting a mandrel in the cavity formed by the inner surface of the first pipe 110 and applying a radial pressure on the outer surface of the second pipe 120 to make the second pipe 120 undergo plastic diameter reduction deformation and then closely adhere to the first pipe 110.

[0087] Please refer to Figure 11 , Figure 11 is Figure 1 a schematic diagram of a scene of another preferred embodiment of step S400 shown in. As in Figure 10 and Figure 11As shown, in step S200, it is selected to form the alloy layer 130 on the outer surface of the first pipe fitting 110. After the second pipe fitting 120 is sleeved outside the first pipe fitting 110 in step S300, the second pipe fitting 120 and the first pipe fitting 110 are not in close contact. Therefore, the multi-layer pipe 104 needs to be subjected to a pressing and compounding process to obtain a multi-layer pipe 104 with close contact between each layer. As described above, the preferred method of the pressing and compounding process in step S400 is to perform plastic necking on the second pipe 120. When performing the plastic necking, the radial pressure applied to the outer surface of the second pipe fitting 120 forces the second pipe fitting 120 to undergo plastic necking deformation. However, at the same time, in order to prevent the first pipe 110 from easily deforming, so as to maintain the pipe diameter that the external anti-corrosion metal composite pipe 103 should have, a mandrel 204 is arranged in the cavity formed by the inner surface of the first pipe 110. The mandrel 204 is usually made of cemented carbide. Due to the presence of the mandrel 204, even if a large enough radial pressure has been applied to the outer surface of the second pipe fitting 120, the first pipe 110 is not easily deformed irreversibly by plastic necking. The radial pressure can be achieved by using the extrusion pressure between the necking die in the cold drawing process and the second pipe 120, or by using a spinning machine to apply extrusion pressure to the second pipe 120, or by using static pressure such as a preset air pressure difference or hydraulic pressure difference applied to the outer surface of the second pipe 120. Those skilled in the art can select a suitable implementation method of the radial pressure according to the pipe diameter and material of the second pipe 120.

[0088] After step S400 is executed, the multi-layer tube 104 also needs to be further heat-treated in step S500 to bring the temperature of the alloy layer 130 to the remelting temperature. Preferably, through repeated experiments, it is verified that when the thickness range of the alloy layer 130 is from 0.01 mm to 0.5 mm, it can satisfy that the alloy layer 130 can firmly and controllably form a metallurgical bond with the first pipe 110 and the second pipe 120 respectively, and finally enable the first pipe 110 to form a metallurgical bond with sufficient strength with the second pipe 120 through the alloy layer 130. At the same time, further experimental verification shows that when the thickness of the first pipe 110 and the second pipe 120 is set to be at least twice the thickness of the alloy layer 130, due to the sufficient thickness of the first pipe 110 and the second pipe 120, even if there are slight deviations in temperature control or heating duration during the remelting process of the alloy layer 130, it is not easy for the components of the alloy layer 130 to diffuse excessively into the first pipe 110 and the second pipe 120. Preferably, in this embodiment, the material of the first pipe 110 includes any one or both of carbon steel and iron-based alloys; the material of the second pipe 120 includes any one, any combination, or all of alloy steel, 316L stainless steel, nickel-based alloys, cobalt-based alloys, and titanium alloys; the material of the alloy layer 130 includes any one, any combination, or all of nickel-based alloys, cobalt-based alloys, or iron-based alloys doped with boron and / or silicon. The material selection of the second pipe 120 is highly related to the working scenario of the external anti-corrosion metal composite pipe 103 and can be flexibly selected according to the actual situation, and the present invention does not limit this. Preferably, the thickness range of the first pipe 110 is from 3 mm to 20 mm, and the thickness of the second pipe 120 is from 1 mm to 3 mm.

[0089] Preferably, the steps of the heat treatment in step S500 include: placing the multi-layer tube 104 in a heating furnace and heating the multi-layer tube 104 as a whole; or along a predetermined feeding direction, sequentially transporting multiple sections of the multi-layer tube 104 into the heating furnace for segmented heating. Whether it is the overall heating or the segmented heating, making the temperature change of the heated section of the multi-layer tube 104 located in the heating furnace increase in a gradient manner is helpful to improve the remelting effect of the alloy layer 130.

[0090] Preferably, the gradient increase includes the following stages: the first stage, continuously heating the heated section to make the temperature of the heated section reach the first temperature; the second stage, continuing to heat the heated section to make the temperature of the heated section reach the second temperature; the third stage, continuing to heat the heated section to make the temperature of the heated section reach the remelting temperature. According to the specific material selection of the first pipe 110, the second pipe 120 and the alloy layer 130 listed in this embodiment, the melting point of the first pipe 110 is the same as or close to the melting point of elemental iron, that is, not higher than 1538 °C, and the melting point of the second pipe 120 generally falls within the range of 1290 °C to 1450 °C. The melting point of the alloy layer 130 is preferably adjusted to fall within the range of 850 °C to 1100 °C. Correspondingly, the first temperature is not higher than 750 °C, the second temperature is greater than the first temperature and less than the remelting temperature.

[0091] Preferably, in order to improve the temperature uniformity of the heated section, the heated section can be subjected to constant temperature and heat preservation treatment after the temperature of the heated section reaches a preset temperature. Preferably, in the first stage, when the temperature of the heated section reaches the first temperature, the heated section is heat-preserved for the first duration; in the second stage, when the temperature of the heated section reaches the second temperature, the heated section is heat-preserved for the second duration; in the third stage, when the temperature of the heated section reaches the remelting temperature, the heated section is heat-preserved for the third duration. The first duration, the second duration and the third duration preferably do not exceed 600 seconds. It should be particularly noted that the constant temperature and heat preservation treatment can be realized by periodically resting the heated section in the heating furnace so that the heated section continuously stays in the heating furnace and is maintained at a constant temperature. However, this is not the only method for the constant temperature and heat preservation treatment. On the contrary, the multi-layer pipe 104 can move along the predetermined feeding direction under the drive of equipment such as feeding wheels and feeding rollers on the production line. By reasonably setting the movement speed of the multi-layer pipe 104, the flow-through duration of the heated section in the heating furnace can be regarded as the heat preservation duration of the heated section while the heated section is heated to the first temperature, the second temperature or the remelting temperature in the heating furnace.

[0092] Similarly to the principle mentioned above, considering the precise control of the heating temperature, the heating furnace can be realized by using an intermediate frequency induction heating furnace. The intermediate frequency induction heating furnace includes one or more heating coils, and a temperature measuring instrument is arranged on each heating coil for real-time monitoring and feedback of temperature information. The working current frequency of the heating coil is preferably set within the range of 500 Hz to 12000 Hz.

[0093] To avoid delamination between the alloy layer 130 and the second pipe 120 during the heating of the multi-layer pipe 104, preferably, when performing the overall heating or the segmented heating on the multi-layer pipe 104, a pressing force can be applied to the outside of the multi-layer pipe 104. For example, a suitable set of pressing rollers can be used to press the outer surface of the second pipe 120, so that the second pipe 120 and the alloy layer 130 can be more closely attached, and it is also easier for the alloy layer 130 to form a metallurgical bond with the second pipe 120.

[0094] Further preferably, when performing the overall heating or the segmented heating on the multi-layer pipe 104, the multi-layer pipe 104 is rotated around its central axis, and / or the induction coil of the heating furnace is arranged to rotate around the multi-layer pipe 104, which helps the multi-layer pipe 104 to be heated evenly.

[0095] Preferably, when performing the overall heating or the segmented heating on the multi-layer pipe 104, the inner cavity of the multi-layer pipe 104 is sealed, and a protective gas is injected into the inner cavity so that the air pressure value in the inner cavity is not lower than a predetermined threshold. This helps to inhibit the separation and delamination of the second pipe 120 and the first pipe 110, and also helps to reduce the generation of scale on the inner surface of the first pipe 110. Tests have found that the optimal solution is when the range of the predetermined threshold falls within the range of 0.1 Mpa to 10 Mpa.

[0096] In step S600, the heated multi-layer pipe 104 is cooled to obtain the Figure 9 outer anti-corrosion metal composite pipe 103 as shown. Preferably, the steps of the cooling treatment include: a rapid cooling device is provided at the discharge port of the multi-layer pipe 104 to cool the multi-layer pipe 104. This rapid cooling device is typically a spray device using water as the cooling medium or an air-cooling device using gas as the cooling medium. In other embodiments, the multi-layer pipe 104 can also be cooled by natural placement.

[0097] Preferably, in order to refine the grains and eliminate internal stresses, thereby improving the performance of the outer anti-corrosion metal composite pipe 103, after the cooling treatment in step S600, the following preferred steps can also be performed: tempering the outer anti-corrosion metal composite pipe 103.

[0098] It should be particularly noted that Figures 2 to 9 in each of the illustrated embodiments, and Figures 8 to 11 in each of the illustrated embodiments, it is premised on the second pipe provided in step S100 corresponding to the corrosion-resistant layer of the metal composite pipe to illustrate the execution of Figure 1After each step of the specific embodiments shown, how to obtain the metal composite pipe. Accordingly, the material of the second pipe is selected from metal alloys with corrosion resistance functions, including any one, any combination, or all of alloy steel, 316L stainless steel, nickel-based alloy, cobalt-based alloy, and titanium alloy. At the same time, the material of the first pipe provided in step S100 is selected from metal alloys with lower costs, including any one or both of carbon steel and iron-based alloy. However, those skilled in the art can understand that if the materials of the first pipe and the second pipe are interchanged, it is equivalent to corresponding the first pipe to the corrosion-resistant layer of the metal composite pipe, which means that only the first pipe and the second pipe are mirror-inverted in the entire manufacturing process of the metal composite pipe. Refer to Figures 2 to 9 each of the embodiments shown, and Figures 8 to 11 each of the embodiments shown, applying the description and explanation of the second pipe to the description and explanation of the first pipe, and applying the description and explanation of the first pipe in each of the above embodiments to the description and explanation of the second pipe, a complete technical solution can also be obtained.

[0099] It should be particularly emphasized that although Figure 1 the operations of the manufacturing method of the metal composite pipe of the present invention are described in a specific order, however, this does not require or imply that these operations must be performed in this specific order, or that all the operations shown must be performed to achieve the desired result. On the contrary, the steps depicted in the flowchart can be changed in the execution order. Additionally or alternatively, certain steps can be omitted, multiple steps can be combined into one step for execution, and / or one step can be decomposed into multiple steps for execution.

[0100] In addition, the present invention also provides a pipeline for waste incineration equipment or oil and gas transmission equipment. Part or all of this pipeline is constructed using the metal composite pipe prepared by the manufacturing method described above. For example, the inner corrosion-resistant metal composite pipe 101 is used to construct the flue gas discharge pipeline of the waste incineration equipment, and the outer corrosion-resistant metal composite pipe 103 is used to construct the underwater cooling pipeline of the oil and gas transmission equipment.

[0101] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description. All changes within the meaning and scope of the equivalent elements of the claims are encompassed in the present invention. Any reference signs in the claims should not be regarded as limiting the claimed rights. In addition, obviously, the word "including" does not exclude other components, units, or steps, and the singular does not exclude the plural.

[0102] The manufacturing method of the metal composite pipe provided by the present invention forms a metallurgical bond between the alloy layer and the first pipe and the second pipe respectively by setting an alloy layer between the first pipe and the second pipe and remelting it, so that the first pipe forms an interfacial bond with the second pipe through the alloy layer. The metal composite pipe thus manufactured can meet the performance consistency requirements at multiple angles such as different pipe diameters, different length positions, and different angles. Due to the high strength of the metallurgical bond, the first pipe and the second pipe have sufficient interfacial bond strength. Even if subsequent plastic deformation machining processes are performed on the metal composite pipe, such as pipe bending and diameter reduction, it is difficult for the layers of the metal composite pipe to separate. Compared with various existing metallurgical composite processes for manufacturing metal composite pipes, the manufacturing method of the metal composite pipe provided by the present invention has the advantages of simple process, low cost, strong compatibility, high safety, and high yield rate respectively.

[0103] The above-disclosed are only some preferred embodiments of the present invention, and the scope of the rights of the present invention cannot be limited thereby. Equivalent changes made according to the claims of the present invention still fall within the scope covered by the present invention.

Claims

1. A manufacturing method of a metal composite pipe, the method comprising: Providing a first pipe and a second pipe, both the first pipe and the second pipe being made of metal, the first pipe having a first surface and the second pipe having a second surface; Attaching alloy powder to the first surface or the second surface to form an alloy layer covering the first surface or the second surface; Coaxially sleeving the first pipe and the second pipe, with the first surface facing the second surface and the alloy layer being between the first surface and the second surface to form a multi-layer pipe; Performing a pressing and composite treatment on the multi-layer pipe to cause an interference fit between the first pipe and the second pipe; Performing a heating treatment on the multi-layer pipe to bring the temperature of the alloy layer to its remelting temperature; Performing a cooling treatment on the multi-layer pipe to obtain a metal composite pipe, wherein the alloy layer in the metal composite pipe forms a metallurgical bond with the first surface and the second surface respectively, and the first pipe forms an interfacial bond with the second pipe through the alloy layer.

2. The manufacturing method according to claim 1, wherein the step of performing a heating treatment on the multi-layer pipe comprises: Placing the multi-layer pipe in a heating furnace and performing overall heating on the multi-layer pipe; Or Sequentially transporting multiple sections of the multi-layer pipe to the heating furnace along a predetermined feeding direction for segmented heating.

3. The manufacturing method according to claim 2, wherein, The step of overall heating or segmented heating comprises: Controlling the power of the heating furnace such that the temperature of the heated section of the multi-layer pipe located within the heating furnace increases in a gradient manner.

4. The manufacturing method according to claim 3, wherein, The gradient increase includes the following stages: A first stage, continuously heating the heated section to bring the temperature of the heated section to a first temperature; A second stage, continuing to heat the heated section to bring the temperature of the heated section to a second temperature; A third stage, continuing to heat the heated section to bring the temperature of the heated section to the remelting temperature.

5. The manufacturing method according to claim 4, wherein: The first temperature is not higher than 750 °C; The second temperature is greater than the first temperature and less than the remelting temperature.

6. The manufacturing method according to claim 2, wherein: When performing overall heating or segmented heating on the multi-layer pipe, the multi-layer pipe rotates around its central axis, and / or the induction coil group of the heating furnace rotates around the multi-layer pipe.

7. The manufacturing method according to claim 2, wherein: When performing overall heating or segmented heating on the multi-layer pipe, a pressing force is applied outside the multi-layer pipe.

8. The manufacturing method according to claim 2, wherein: When performing overall heating or segmented heating on the multi-layer pipe, the inner cavity of the multi-layer pipe is sealed, and a protective gas is injected into the inner cavity such that the air pressure value in the inner cavity is not lower than a predetermined threshold.

9. The manufacturing method according to claim 8, wherein: The range of the predetermined threshold is 0.1 Mpa to 10 Mpa.

10. The manufacturing method according to claim 1, wherein, The step of performing a cooling treatment on the multi-layer pipe comprises: Providing a spraying device or an air cooling device at the discharge port of the multi-layer pipe to cool the multi-layer pipe.

11. According to the manufacturing method described in claim 10, after the cooling treatment, the manufacturing method further includes: Performing a tempering treatment on the metal composite pipe.

12. According to the manufacturing method described in claim 1, before attaching the alloy powder, the manufacturing method further includes: Roughening the surface of the first surface or the second surface that bears the alloy powder.

13. According to the manufacturing method described in any one of claims 1 to 12, wherein: The melting point of the alloy layer is lower than the melting points of the first pipe and the second pipe; The thickness range of the alloy layer is from 0.01 mm to 0.5 mm, and the thicknesses of the first pipe and the second pipe are at least twice the thickness of the alloy layer.

14. According to the manufacturing method described in claim 13, wherein: The first pipe is sleeved outside the second pipe, the first surface is the inner surface of the first pipe, and the second surface is the outer surface of the second pipe; The alloy powder is sprayed on the first surface or the second surface.

15. The manufacturing method according to claim 14, wherein, The step of performing a pressing and composite treatment on the multi-layer pipe includes: Sealing the cavity formed by enclosing the inner surface of the second pipe, and injecting a pressurizing medium into the cavity to cause the second pipe to undergo plastic expansion deformation and then closely adhere to the first pipe; The material of the first pipe includes any one or both of carbon steel and iron-based alloys; The material of the second pipe includes any one, any combination, or all of alloy steel, 316L stainless steel, nickel-based alloys, cobalt-based alloys, and titanium alloys; The material of the alloy layer includes any one, any combination, or all of nickel-based alloys, cobalt-based alloys, or iron-based alloys doped with boron and / or silicon.

16. According to the manufacturing method described in claim 13, wherein: The second pipe is sleeved outside the first pipe, the first surface is the outer surface of the first pipe, and the second surface is the inner surface of the second pipe; The alloy powder is sprayed on the first surface or the second surface.

17. The manufacturing method according to claim 16, wherein, The step of performing a pressing and composite treatment on the multi-layer pipe includes: Setting a mandrel in the cavity formed by enclosing the inner surface of the first pipe, and applying a radial pressure on the outer surface of the second pipe to cause the second pipe to undergo plastic shrinkage deformation and then closely adhere to the first pipe; The material of the first pipe includes any one or both of carbon steel and iron-based alloys; The material of the second pipe includes any one, any combination, or all of alloy steel, 316L stainless steel, nickel-based alloys, cobalt-based alloys, and titanium alloys; The material of the alloy layer includes any one, any combination, or all of nickel-based alloys, cobalt-based alloys, or iron-based alloys doped with boron and / or silicon.

18. A pipe for a waste incineration device or an oil and gas transmission device, wherein a part or all of the pipe is constructed using a metal composite pipe prepared by the manufacturing method described in any one of claims 1 to 17.

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