A method for preparing a metallurgical composite steel pipe

Abstract

The present invention provides a method for preparing a metallurgical composite steel pipe, which solves the problems existing in the previous composite technology and prepares a metallurgical composite steel pipe with significantly better bonding performance than existing products. The preparation method includes: S1: a seamless steel pipe is selected as the base layer, and the base layer is subjected to inner surface treatment; S2: a rod is selected as the inner covering layer, and the inner covering layer is subjected to outer surface treatment; S3: the inner covering layer rod is pressed into the base pipe by a press until the bottom end is flush, and the top inner covering layer is higher than the base layer, so that the two achieve an interference fit to obtain a mechanical composite tube blank; S4: the two ends of the mechanical composite tube blank are sealed and welded, and a vacuum interface is reserved at the top and vacuumed; S5: the mechanical composite tube blank is heated to the minimum rolling temperature of the inner covering material and kept warm; S6: the mechanical composite tube blank is forged to a preset diameter by a fast forging machine to obtain a metallurgical composite tube blank; S7: the forged composite tube blank is formed to obtain a finished metallurgical composite steel pipe.

Description

[Technical field]

[0001] The invention relates to the technical field of iron and steel metallurgy, and in particular to a method for preparing a metallurgical composite steel pipe. [Background technology]

[0002] Compared with common anti-corrosion solutions such as corrosion inhibitors, coatings, and material upgrades, bimetallic composite pipes are recognized by the petroleum industry as a solution to high-content H2S, CO2, and Cl - Bimetallic composite pipes include mechanical composite pipes and metallurgical composite pipes. Compared with mechanical composite pipes, metallurgical composite pipes have higher bonding strength, which avoids the problems of lining collapse and bulging of mechanical composite pipes. They are also easier to weld and easier to process. Traditional metallurgical composite pipes are mostly produced by explosive composite plate welding, internal cladding, centrifugal casting and other processes, which have disadvantages such as straight welds, uneven inner coating, complex processes and high production costs.

[0003] As the service conditions of pipelines such as oil and gas fields and boiler heat exchange tube bundles become increasingly harsh, it is necessary to develop a preparation method for metallurgical composite steel pipes to address the deficiencies of existing technologies and meet the market's urgent demand for metallurgical composite steel pipe products. [Summary of the invention]

[0004] The present invention provides a method for preparing a metallurgical composite steel pipe, which solves the problems existing in the previous composite technology and prepares a metallurgical composite steel pipe with a bonding performance significantly better than that of existing products.

[0005] Furthermore, the preparation method of the present invention comprises the following steps:

[0006] S1: The base layer is made of seamless steel pipe and the inner surface of the base layer is treated;

[0007] S2: The inner coating is made of bar material and the outer surface of the inner coating is treated;

[0008] S3: The inner coating rod is pressed into the base tube by a press until the bottom end is flush with the top inner coating layer being higher than the base layer, so that the two achieve an interference fit to obtain a mechanical composite tube blank;

[0009] S4: Sealing and welding the two ends of the mechanical composite tube blank, reserving a vacuum interface at the top and performing vacuum treatment;

[0010] S5: heating the mechanical composite tube blank to the minimum rolling temperature of the inner cladding material and keeping the temperature;

[0011] S6: Forging the mechanical composite tube blank to a preset diameter by a fast forging machine to obtain a metallurgical composite tube blank;

[0012] S7: The forged composite tube blank is formed by a piercing-cold rolling-heat treatment process to obtain a finished metallurgical composite steel tube.

[0013] Furthermore, the S1 middle base seamless steel pipe includes low carbon steel, medium carbon steel and high carbon steel, and the inner surface is treated to achieve an inner surface roughness of less than 70 μm.

[0014] Furthermore, the inner coating bar material includes martensite, austenite, duplex steel and nickel-based alloy, and the outer surface is treated to achieve an outer surface roughness of less than 70 μm.

[0015] Furthermore, the length of the inner coating rod in S2 is 5 to 10 mm greater than the length of the base steel pipe.

[0016] Furthermore, the interference in S3 is 50-100 μm.

[0017] Furthermore, the heating temperature in S5 is in the range of 1150°C to 1200°C, and the holding time is 6 to 8 hours;

[0018] Furthermore, the S6 fast forging process enables the base layer and the inner coating layer to achieve atomic bonding, and the S6 is specifically as follows:

[0019] S61: The fast forging machine forges the heated composite tube billet to 20% to 33% of the original diameter;

[0020] S62: Perform ultrasonic flaw detection on the forged composite tube billet and perform head cutting on the uncompounded areas that may exist at both ends;

[0021] S63: polishing and grinding the outer surface of the forged composite tube blank to remove the oxide scale on the outer surface to form a metallurgical composite tube blank.

[0022] Furthermore, the number of sealing passes in the S4 sealing process is not less than 2.

[0023] Furthermore, the vacuum degree in S4 is 5-10Pa.

[0024] Furthermore, the piercing-cold rolling-heat treatment process in S7 is specifically as follows:

[0025] S71: heating the metallurgical composite tube blank and punching it through a punching machine to form a perforated rough tube;

[0026] S72: cold rolling the perforated rough pipe, with the cold rolling diameter reduction amount being 10% to 20% and the wall reduction amount being 40% to 50%, to obtain a formed metallurgical composite steel pipe;

[0027] S73: According to the materials of the base layer and the inner covering layer, the formed metallurgical composite steel pipe is treated by annealing, solid solution and tempering heat treatment system.

[0028] Furthermore, the heating temperature range in S71 is: 1150° C. to 1200° C., the high temperature section insulation time is 1 to 1.5 hours, and the furnace residence time is 4 to 5 hours.

[0029] Compared with the prior art, the present invention can achieve the following technical effects:

[0030] The advantages of the present invention are:

[0031] 1: Solved the problems of lining bulging, collapse, poor heat transfer, etc. caused by low bonding strength of mechanical composite pipes;

[0032] 2: It avoids the problems of stress concentration and micro cracks caused by the jagged interface in the traditional explosive metallurgical composite technology, as well as the problem of uneven inner coating caused by the centrifugal casting process. At the same time, the production efficiency and cost are higher than the internal cladding metallurgical composite technology.

[0033] Of course, any product implementing the present invention does not necessarily need to achieve all of the above-mentioned technical effects at the same time.

Brief Description of the Drawings

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention.

[0035] Figure 1 This is a state diagram of the inner coating bar before being pressed into the base seamless steel pipe in the preparation method provided by one embodiment of the present invention;

[0036] Figure 2 This is a state diagram of the inner coating bar before being pressed into the base seamless steel pipe in the preparation method provided by one embodiment of the present invention;

[0037] Figure 3 is a top view of equipment in a preparation process provided by an embodiment of the present invention;

[0038] Figure 4 This is a microstructure diagram of the bonding interface of a finished metallurgical composite pipe provided by an embodiment of the present invention.

[0039] Among them, in the figure:

[0040] 1-base seamless steel pipe; 2-inner coating bar; 3-press machine. [Specific implementation method]

[0041] In order to better understand the technical solution of the present invention, the embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0042] It should be clear that the described embodiments are only some embodiments of the present invention, not all 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.

[0043] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0044] The present invention provides a method for preparing a metallurgical composite steel pipe, the preparation method comprising the following steps:

[0045] S1: The base layer is made of seamless steel pipe, which is made of low carbon steel, medium carbon steel or high carbon steel. The base layer is treated on the inner surface to make the inner surface roughness reach less than 70μm;

[0046] S2: The inner coating is made of bar material, and the material includes corrosion-resistant alloys such as martensite, austenite, duplex steel or nickel-based alloy. The inner coating is treated on the outer surface to make the outer surface roughness reach less than 70μm, such as Figure 1 As shown;

[0047] S3: Use a press to press the inner coating bar into the base tube until the bottom end is flush. Figure 2 As shown, the top inner coating is slightly higher than the base layer by about 5 to 10 mm. The two are made to have an interference fit, with an interference amount of 50 to 100 μm, to obtain a mechanical composite tube blank;

[0048] S4: Sealing welding is performed on both ends of the mechanical composite tube blank, with the number of sealing welding passes not less than 2. A vacuuming interface is reserved at the top and vacuuming is performed, with the vacuum degree reaching 5-10Pa. Figure 3 As shown;

[0049] S5: heating the mechanical composite tube billet to the minimum rolling temperature of the inner cladding material, the temperature range is: 1150 ℃ ~ 1200 ℃, and keeping the temperature for 6 to 8 hours;

[0050] S6: Forging the mechanical composite tube blank to a preset diameter by a fast forging machine, so that the base layer and the inner coating layer reach an interlayer atomic bonding state, and a metallurgical composite tube blank is obtained; the fast forging specifically includes:

[0051] 1) The fast forging machine forges the heated composite tube billet to 20% to 33% of the original diameter;

[0052] 2) Perform ultrasonic flaw detection on the forged composite tube billet and perform head cutting on the uncompounded areas that may exist at both ends;

[0053] 3) polishing and grinding the outer surface of the forged composite tube blank to remove the oxide scale on the outer surface to form a metallurgical composite tube blank;

[0054] S7: The forged composite tube blank is formed by a piercing-cold rolling-heat treatment process to obtain a finished metallurgical composite steel tube, specifically including:

[0055] 1) The metallurgical composite tube blank is heated at a temperature ranging from 1150°C to 1200°C, the high temperature section is kept warm for 1 to 1.5 hours, the furnace residence time is 4 to 5 hours, and the tube is perforated by a perforator to form a perforated rough tube;

[0056] 2) The perforated rough pipe is cold rolled, the cold rolling diameter reduction is 10% to 20%, and the wall reduction is 40% to 50%, to obtain a formed metallurgical composite steel pipe.

[0057] 3) According to the materials of the base layer and the inner covering layer, the formed metallurgical composite steel pipe is treated with different heat treatment systems such as annealing, solid solution, and tempering.

[0058] Embodiment 1:

[0059] like Figure 4 As shown, the present invention adopts the following steps in the preparation process:

[0060] 1. The base layer is made of 30CrMoA seamless steel pipe with specifications of Φ600*200*1000mm, and the inner surface is turned or ground to a roughness of less than 70μm.

[0061] 2. The coating is made of N08825 bar material, specification Φ202*1005, the outer surface is turned to Φ200, and the overburden is guaranteed to be 50~100μm;

[0062] 3. Use a 10,000-ton press to press the N08825 bar into the 30CrMoA seamless steel pipe until the bottom end is flush and the top end is slightly higher by about 5mm;

[0063] 4. Both ends are sealed and welded, and a vacuum interface is reserved at the top, with a vacuum degree of 5Pa;

[0064] 5. Heating temperature 1180℃ and keeping warm for 6 hours;

[0065] 6. The operation of the fast forging machine is divided into two times. The first forging is to Φ450*1778mm, and then it is heated to 1180℃ for the second forging, and the second forging is to Φ273*4800mm. After ultrasonic flaw detection, the uncompounded areas at both ends are cut, and the surface is polished and ground to obtain a Φ273*4500 metallurgical composite tube billet, which is then sawed into two Φ273*2250 metallurgical composite tube billets;

[0066] 7. Use inclined bottom furnace for heating, the heating temperature is 1180℃, the furnace time is 4 hours, and the high temperature section insulation time is 1 hour; use 720 fungus puncher for punching to obtain Φ320*18*7000 perforated rough pipe.

[0067] 8. Cold rolling is performed by a cold pilger mill to obtain a Φ273*12.7*10200 formed metallurgical composite steel pipe, with a cold rolling diameter reduction of 47 mm and a wall reduction of 5.3 mm;

[0068] 9. Use 910℃, keep warm for 25 minutes, then water quench, and then use 610℃, keep warm for 45 minutes, and then air cool and temper.

[0069] 10. Straighten the heat-treated metallurgical composite steel pipe and polish the inner wall with a 120-mesh thousand-blade wheel to obtain a finished metallurgical composite steel pipe.

[0070] like Figure 4 As shown in the microstructure diagram of the bonding interface of the finished metallurgical composite pipe of the present invention, during the transition from N08825 to 30CrMoA carbon steel, the content of elements such as chromium, nickel, and molybdenum decreases, and the iron element increases. The diffusion of elements such as chromium, nickel, and molybdenum can be clearly seen in the N08825 alloy, and the diffusion distance is about 40μm.

[0071] The above is a detailed introduction to the preparation method of a metallurgical composite steel pipe provided in the embodiment of the present application. The description of the above embodiment is only used to help understand the method and its core idea of ​​the present application; at the same time, for those skilled in the art, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

[0072] For example, certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different nouns to refer to the same component. This specification and claims do not use differences in names as a way to distinguish components, but use differences in the functions of components as the criteria for distinction. As mentioned throughout the specification and claims, "including" and "comprising" are open-ended terms, so they should be interpreted as "including / including but not limited to". "Approximately" means that within an acceptable error range, those skilled in the art can solve the technical problem within a certain error range and basically achieve the technical effect. The subsequent description of the specification is a preferred embodiment of the present application, but the description is for the purpose of illustrating the general principles of the present application, and is not used to limit the scope of the present application. The scope of protection of the present application shall be determined by the definition of the attached claims.

[0073] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a product or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such a product or system. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the product or system including the elements.

[0074] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0075] The above description shows and describes several preferred embodiments of the present application, but as mentioned above, it should be understood that the present application is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the application concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art do not deviate from the spirit and scope of the present application, and should be within the scope of protection of the claims attached to the present application.

Claims

1. A method for preparing a metallurgical composite steel pipe, characterized in that: The preparation method comprises the following steps: S1: a seamless steel pipe is selected as the base layer, and the base layer is subjected to inner surface treatment; S2: The inner coating is made of bar material and the outer surface of the inner coating is treated; S3: The inner coating bar is pressed into the base seamless steel pipe by a press until the bottom end is flush, and the top inner coating is higher than the base, so that the two achieve interference fit to obtain a mechanical composite pipe blank; S4: Sealing and welding the two ends of the mechanical composite tube blank, reserving a vacuum interface at the top and performing vacuum treatment; S5: heating the mechanical composite tube blank to the minimum rolling temperature of the inner cladding material and keeping the temperature; S6: forging the mechanical composite tube blank to a preset diameter by a fast forging machine to obtain a metallurgical composite tube blank; S7: forming the metallurgical composite tube blank by using a perforation-cold rolling-heat treatment process to obtain a finished metallurgical composite steel tube; The heating temperature range in S5 is: 1150°C to 1200°C, and the insulation time is 6 to 8 hours; The S6 fast forging process allows the base layer and the inner coating layer to achieve atomic bonding, and the S6 is specifically as follows: S61: the fast forging machine forges the heated composite tube blank to 20% to 33% of the original diameter; S62: Perform ultrasonic flaw detection on the forged composite tube billet and perform head cutting on the uncompounded areas that may exist at both ends; S63: polishing and grinding the outer surface of the forged composite tube blank to remove the oxide scale on the outer surface to form a metallurgical composite tube blank; The number of sealing passes in the S4 sealing process is not less than 2, and the vacuum degree is 5-10Pa; The piercing-cold rolling-heat treatment process in S7 is specifically as follows: S71: heating the metallurgical composite tube blank and piercing it through a piercing machine to form a perforated rough tube; S72: cold rolling the perforated rough pipe, with the cold rolling diameter reduction amount being 10% to 20% and the wall reduction amount being 40% to 50%, to obtain a formed metallurgical composite steel pipe; S73: Based on the materials of the base layer and the inner covering layer, the formed metallurgical composite steel pipe is treated by annealing, solid solution and tempering heat treatment system; The heating temperature range in S71 is: 1150° C. to 1200° C., and the furnace dwelling time is 4 to 5 hours.

2. The preparation method according to claim 1, characterized in that: The S1 medium-base seamless steel pipe comprises low-carbon steel, medium-carbon steel or high-carbon steel, and the inner surface is treated to achieve an inner surface roughness of less than 70 μm.

3. The preparation method according to claim 1, characterized in that: The inner coating layer rod material comprises martensite, austenite, dual-phase steel or nickel-based alloy, and the outer surface is treated to achieve an outer surface roughness of less than 70 μm.

4. The preparation method according to claim 1, characterized in that: The length of the inner coating rod in S2 is 5 to 10 mm greater than the length of the base steel pipe.

5. The preparation method according to claim 1, characterized in that: The interference in S3 is 50 to 100 μm.

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