A high corrosion-resistant stainless steel-lined composite pipe and its preparation process

Abstract

This application discloses a high corrosion-resistant stainless steel-lined composite pipe and its manufacturing process, belonging to the field of metal material processing technology. This application involves laser drilling on two welding surfaces of a carbon steel plate to form microchannel structures of varying depths; then, a mixture of tin powder and powdered molybdenum disulfide is uniformly spread on the welding surfaces, allowing it to melt and flow under the high temperature during the carbon steel welding process, fully filling the microchannel structures; finally, after cooling and solidification, a reinforced carbon steel pipe without weld cracks, porosity, or gaps is obtained. Using this reinforced carbon steel pipe as the outer layer and a stainless steel pipe as the inner layer, a high corrosion-resistant stainless steel-lined composite pipe is prepared through a production technology combining drawing and diameter reduction with water injection and pressurization. This stainless steel composite pipe avoids the risk of weld defects expanding during processing and possesses excellent interfacial bonding strength and corrosion resistance.

Description

Technical Field

[0001] This application relates to the field of metal material processing technology, specifically to a high corrosion-resistant stainless steel-lined composite pipe and its preparation process. Background Technology

[0002] In today's industrial manufacturing sector, stainless steel composite pipes are widely used in construction, chemical engineering, marine engineering, and many other industries due to their combination of the corrosion resistance of stainless steel and the high strength of steel. However, during the manufacturing process, thicker steel may develop defects such as porosity and slag inclusions during welding. These defects create weak points at the interface of the stainless steel composite pipe, reducing the interfacial bonding strength. Furthermore, when the composite pipe is subjected to external forces such as pressure or tension, cracks are easily triggered at these defects, providing adhesion points and corrosion channels for corrosive media, accelerating the corrosion process, and ultimately leading to the failure of the stainless steel composite pipe, severely shortening its service life.

[0003] In summary, there is an urgent need to develop innovative technologies to overcome the drawbacks of steel welding areas and improve the quality and performance of stainless steel composite pipes in order to meet the increasingly high standards required by various industries.

[0004] Chinese patent application CN 103722346A discloses a corrosion-resistant composite bimetallic straight seam submerged arc welded steel pipe. The corrosion-resistant metallurgical composite bimetallic straight seam submerged arc welded steel pipe provided in this application adopts hot-rolled metallurgical composite bimetallic steel plate and JCOE pipe manufacturing process and efficient automatic submerged arc welding process. The double-layer metal of the steel pipe achieves complete metallurgical bonding, resulting in high strength, strong integrity, and good corrosion resistance.

[0005] However, the welded area of ​​the composite bimetallic straight seam submerged arc welded steel pipe produced by this method may still have defects such as porosity and slag inclusions, which will ultimately reduce the interfacial bonding strength and corrosion resistance of the composite steel pipe. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this application provides a high corrosion-resistant stainless steel-lined composite pipe and its manufacturing process. The process involves laser etching on two welding surfaces of a carbon steel plate to create microchannel structures of varying depths. A mixture of tin powder and powdered molybdenum disulfide is then uniformly spread onto the welding surfaces, allowing it to melt and flow under the high temperatures of the carbon steel welding process, fully filling the microchannel structures. Finally, after cooling and solidification, a reinforced carbon steel pipe free of weld cracks, porosity, or gaps is obtained. Using this reinforced carbon steel pipe as the outer layer and a stainless steel pipe as the inner layer, a high corrosion-resistant stainless steel-lined composite pipe is manufactured through a production technique combining drawing and diameter reduction with water injection and pressurization. This method effectively repairs weld cracks or gaps that may occur during the processing of the stainless steel composite pipe, significantly improving the interfacial bonding strength and corrosion resistance of the composite pipe.

[0007] To achieve the above objectives, this application adopts the following technical solution:

[0008] In a first aspect, this application provides a high corrosion-resistant stainless steel-lined composite pipe, comprising an inner stainless steel pipe and an outer reinforced carbon steel pipe; the stainless steel pipe and the reinforced carbon steel pipe are composited together by a drawing-and-reduction-diameter-combination-water-injection-pressurization method; each of the two welding surfaces of the reinforced carbon steel pipe is provided with a first microchannel region located at the edge of the welding surface and a second microchannel region located in the middle part of the welding surface; the first microchannel region is arranged with a plurality of first microchannels, and the second microchannel region is arranged with a plurality of second microchannels, wherein the channel size of the first microchannel is larger than the channel size of the second microchannel; one of the two welding surfaces of the reinforced carbon steel pipe is covered with a mixture of tin powder and powdered molybdenum disulfide.

[0009] Secondly, this application provides a manufacturing process for a high corrosion-resistant stainless steel-lined composite pipe, comprising the following steps:

[0010] Stainless steel strip is rolled and welded to obtain stainless steel pipe;

[0011] Laser drilling is performed on two welding surfaces of carbon steel plates, followed by rolling. A mixture of tin powder and powdered molybdenum disulfide is then laid on one of the welding surfaces before welding to obtain a reinforced carbon steel pipe.

[0012] The inner and outer surfaces of the obtained stainless steel pipes and reinforced carbon steel pipes are both surface treated.

[0013] Surface-treated stainless steel pipes and reinforced carbon steel pipes are threaded together to form a composite pipe blank.

[0014] Water is injected into the composite tube blank. After the tube is filled with water, the ends of the tube are sealed by welding.

[0015] Lubricant is applied to the outer surface of the reinforced carbon steel pipe of the composite pipe blank to be injected with water, and then the pipe is drawn and reduced in diameter. After the drawing and reduction is completed, the composite pipe is obtained.

[0016] The welded portions at both ends of the composite pipe are removed to drain the water. The inner and outer surfaces of the composite pipe are cleaned and dried to obtain a high corrosion-resistant stainless steel-lined composite pipe.

[0017] Beneficial technical effects:

[0018] Three microchannel structures were laser-drilled on the two welding surfaces of the carbon steel sheet. The two microchannel structures on the sides, closer to the welding position, were deeper and wider, while the microchannel structure in the middle, farther from the welding position, was shallower and narrower. Because of their proximity to the welding position, the microchannel structures on the sides were more quickly affected by the high welding temperature. A layer of tin powder on their surface rapidly melted and mixed with powdered molybdenum disulfide, filling the deeper microchannel structures and spreading outwards. In the middle microchannel structure, further from the welding position, the tin powder melted under the heat conduction from the molten tin powder flowing from the sides, also mixing with powdered molybdenum disulfide and filling the shallower microchannel structures. Ultimately, the microchannel structures in all three regions, as well as the space between the two welding surfaces, were filled with a mixture of molten tin powder and powdered molybdenum disulfide. Simultaneously, due to the layered crystal structure of molybdenum disulfide, molybdenum atoms are sandwiched between two layers of sulfur atoms, forming a single layer. These layers are bonded by relatively weak van der Waals forces, making relative sliding between the layers easy. When subjected to external force, the layered structure of molybdenum disulfide easily slides against each other, effectively reducing friction between the surfaces and providing lubrication. This results in a highly uniform and dense distribution of the molten tin powder and powdered molybdenum disulfide mixture filling the microchannel structure in the three regions and between the two welding surfaces. Upon cooling, the molten tin powder mixed with powdered molybdenum disulfide rapidly solidifies, forming a uniform and dense mechanical interlocking structure free of cracks, pores, or gaps in the microchannel structure of the three regions and between the two welding surfaces. This results in a reinforced carbon steel pipe without weld cracks or gaps. Furthermore, the molybdenum disulfide mixed with tin powder enhances the acid and alkali resistance of the welding area.

[0019] To avoid welding defects, this solution further utilizes a reinforced carbon steel pipe as the outer layer and a stainless steel pipe as the inner layer. Through a production technique combining drawing and diameter reduction with water injection pressurization, a highly corrosion-resistant stainless steel-lined composite pipe was manufactured. This stainless steel composite pipe exhibits high interfacial bonding strength, and no weak points are formed at the interface, thus preventing a reduction in interfacial bonding strength. Furthermore, when subjected to external forces such as pressure and tension, the stainless steel composite pipe is less prone to crack propagation, significantly enhancing its corrosion resistance and extending its service life. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of a high corrosion-resistant stainless steel-lined composite pipe.

[0021] Figure 2 This is a schematic diagram of the process for preparing highly corrosion-resistant stainless steel-lined composite pipes.

[0022] Figure 3 This is a cross-sectional schematic diagram of the welding condition of the reinforced carbon steel pipe.

[0023] Reference numerals: 1. Stainless steel tube; 2. Reinforced carbon steel tube; 3. First microchannel region; 4. Second microchannel region; 5. First microchannel; 6. Second microchannel; 7. Mixture of tin powder and powdered molybdenum disulfide. Detailed Implementation

[0024] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the application will be further described in detail below with reference to embodiments. However, this should not be construed as limiting the scope of this application to the following examples. All other embodiments obtained by those skilled in the art without creative effort without departing from the above-described methodological spirit of this application are within the scope of protection of this application.

[0025] In this application, the terminology used is for the purpose of describing particular embodiments only and is not intended to limit the application. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] Firstly, such as Figure 1 As shown, this application provides a high corrosion-resistant stainless steel-lined composite pipe, comprising an inner stainless steel pipe 1 and an outer reinforced carbon steel pipe 2; the stainless steel pipe 1 and the reinforced carbon steel pipe 2 are composited together by a drawing-and-reduction-diameter-combination-water-injection-pressurization method; each of the two welding surfaces of the reinforced carbon steel pipe 2 is provided with a first microchannel region 3 located at the edge of the welding surface and a second microchannel region 4 located in the middle of the welding surface; the first microchannel region 3 is provided with a plurality of first microchannels 5, and the second microchannel region 4 is provided with a plurality of second microchannels 6, wherein the channel size of the first microchannel 5 is larger than the channel size of the second microchannel 6; one of the two welding surfaces of the reinforced carbon steel pipe 2 is covered with a layer of a mixture 7 of tin powder and powdered molybdenum disulfide.

[0027] Preferably, the microchannel structure on the two welded surfaces of the reinforced carbon steel pipe 2 is obtained by laser drilling.

[0028] Preferably, the width or depth of the first microchannel 5 is greater than the width or depth of the second microchannel 6.

[0029] More preferably, the width and depth of the first microchannel 5 are both greater than the width and depth of the second microchannel 6;

[0030] Preferably, the width of the first microchannel 5 is 3~5mm and the depth is 1.0~1.5cm; the width of the second microchannel 6 is 1~2mm and the depth is 0.5~0.8cm.

[0031] Preferably, the mass ratio of the tin powder and the powdered molybdenum disulfide mixture 7 is (65~85):(15~35).

[0032] Preferably, the thickness of the layer of tin powder and powdered molybdenum disulfide mixture 7 on the welding surface of the reinforced carbon steel pipe 2 is 1.0~2.0mm.

[0033] Preferably, the stainless steel pipe 1 is made of any one of austenitic stainless steel, ferritic stainless steel, martensitic stainless steel and duplex stainless steel.

[0034] Preferably, the material used for the reinforced carbon steel pipe 2 includes either medium carbon steel or low carbon steel; more preferably, low carbon steel.

[0035] Secondly, this application provides a manufacturing process for a high corrosion-resistant stainless steel-lined composite pipe, such as... Figure 2 As shown, it includes the following steps:

[0036] Stainless steel strip is rolled and welded to obtain stainless steel pipe 1;

[0037] Laser drilling was performed on two welding surfaces of the carbon steel sheet, followed by rolling. A mixture of tin powder and powdered molybdenum disulfide 7 was then applied to one of the welding surfaces before welding, resulting in a reinforced carbon steel pipe 2. The welding details are as follows. Figure 3 As shown;

[0038] The inner and outer surfaces of the stainless steel pipe 1 and the reinforced carbon steel pipe 2 are both surface treated.

[0039] Surface-treated stainless steel tube 1 and reinforced carbon steel tube 2 are threaded together to obtain a composite tube blank.

[0040] Water is injected into the composite tube blank. After the tube is filled with water, the ends of the tube are sealed by welding.

[0041] Lubricant is applied to the outer surface of the reinforced carbon steel pipe 2 of the composite pipe blank to be injected with water, and then the pipe is drawn and reduced in diameter. After the drawing and reduction is completed, the composite pipe is obtained.

[0042] The welded portions at both ends of the composite pipe are removed to drain the water. The inner and outer surfaces of the composite pipe are cleaned and dried to obtain a high corrosion-resistant stainless steel-lined composite pipe.

[0043] Preferably, the thickness of the stainless steel pipe 1 is 2~3mm; the thickness of the reinforced carbon steel pipe 2 is 15.0~25.0mm.

[0044] Preferably, the surface treatment includes alkaline washing, acid washing, sandblasting, and secondary acid washing.

[0045] Preferably, the alkaline washing is performed by immersing in a 5-10 wt% sodium hydroxide solution or potassium hydroxide solution at 40-55°C for 3-10 minutes.

[0046] Preferably, the pickling is performed using a 10-15 wt% sulfuric acid solution, a 50-70 wt% hydrochloric acid solution, or a mixture of both, and the solution is immersed at 40-45°C for 10-15 minutes.

[0047] Preferably, the sandblasting cleaning grade is Sa2 or Sa2.5.

[0048] Preferably, the secondary pickling is performed using a 10-15 wt% sulfuric acid solution, a 50-70 wt% hydrochloric acid solution, or a mixture of both, and is carried out at 45-50°C for 5-10 minutes.

[0049] Preferably, the lubricant includes at least one of synthetic ester lubricants and polyether lubricants.

[0050] The following will describe in detail, with reference to different embodiments, a high corrosion-resistant stainless steel-lined composite pipe and its preparation process provided in this application.

[0051] Example 1:

[0052] like Figure 2 As shown, a manufacturing process for a high corrosion-resistant stainless steel-lined composite pipe includes the following steps:

[0053] 1. Austenitic stainless steel is selected for rolling and welding to obtain stainless steel pipe 1;

[0054] 2. Laser drilling is performed on the two welding surfaces of the low carbon steel plate, followed by rolling. Tin powder and powdered molybdenum disulfide mixture 7 are spread on one of the welding surfaces and then welded to obtain reinforced carbon steel pipe 2.

[0055] 3. Alkali washing is performed on both the inner and outer surfaces of stainless steel pipe 1 and reinforced carbon steel pipe 2: immersion in 5wt% sodium hydroxide solution at 40℃ for 10 minutes; acid washing: immersion in 10wt% sulfuric acid solution at 40℃ for 15 minutes; sandblasting cleaning, with a cleaning grade of Sa2; secondary acid washing: immersion in 10wt% sulfuric acid solution at 45℃ for 10 minutes.

[0056] 4. The surface-treated stainless steel pipe 1 and reinforced carbon steel pipe 2 are threaded together to form a composite pipe blank;

[0057] 5. Fill the composite tube blank with water. After the tube is filled with water, seal the ends of the tube.

[0058] 6. Apply lubricant to the outer surface of the reinforced carbon steel pipe 2 of the composite pipe blank for water injection, and then draw and reduce the diameter. After the drawing and reduction is completed, the composite pipe is obtained.

[0059] 7. Cut off the welded parts at both ends of the composite pipe to drain the water, and clean and dry the inner and outer surfaces of the composite pipe to obtain a high corrosion-resistant stainless steel-lined composite pipe.

[0060] Example 2:

[0061] like Figure 2 As shown, a manufacturing process for a high corrosion-resistant stainless steel-lined composite pipe includes the following steps:

[0062] 1. Ferritic stainless steel is selected for rolling and welding to obtain stainless steel pipe 1;

[0063] 2. Laser drilling is performed on the two welding surfaces of the low carbon steel plate, followed by rolling. Tin powder and powdered molybdenum disulfide mixture 7 are spread on one of the welding surfaces and then welded to obtain reinforced carbon steel pipe 2.

[0064] 3. Alkali washing is performed on both the inner and outer surfaces of stainless steel pipe 1 and reinforced carbon steel pipe 2: immersion in 7wt% potassium hydroxide solution at 45℃ for 6 minutes; acid washing: immersion in 50wt% hydrochloric acid solution at 42℃ for 12 minutes; sandblasting cleaning, with a cleaning grade of Sa2.5; secondary acid washing: immersion in 50wt% hydrochloric acid solution at 47℃ for 7 minutes.

[0065] 4. The surface-treated stainless steel pipe 1 and reinforced carbon steel pipe 2 are threaded together to form a composite pipe blank;

[0066] 5. Fill the composite tube blank with water. After the tube is filled with water, seal the ends of the tube.

[0067] 6. Apply lubricant to the outer surface of the reinforced carbon steel pipe 2 of the composite pipe blank for water injection, and then draw and reduce the diameter. After the drawing and reduction is completed, the composite pipe is obtained.

[0068] 7. Cut off the welded parts at both ends of the composite pipe to drain the water, and clean and dry the inner and outer surfaces of the composite pipe to obtain a high corrosion-resistant stainless steel-lined composite pipe.

[0069] Example 3:

[0070] like Figure 2 As shown, a manufacturing process for a high corrosion-resistant stainless steel-lined composite pipe includes the following steps:

[0071] 1. Martensitic stainless steel is selected for rolling and welding to obtain stainless steel pipe 1;

[0072] 2. Laser drilling is performed on the two welding surfaces of the low carbon steel plate, followed by rolling. Tin powder and powdered molybdenum disulfide mixture 7 are spread on one of the welding surfaces and then welded to obtain reinforced carbon steel pipe 2.

[0073] 3. Alkali washing of both the inner and outer surfaces of stainless steel pipe 1 and reinforced carbon steel pipe 2: Immersion in 10wt% sodium hydroxide solution at 50℃ for 3 minutes; Acid washing: Immersion in a mixture of 10wt% sulfuric acid solution and 50wt% hydrochloric acid solution (volume ratio 1:1) at 45℃ for 10 minutes; Sandblasting cleaning, with a cleaning grade of Sa2; Secondary acid washing: Immersion in a mixture of 10wt% sulfuric acid solution and 50wt% hydrochloric acid solution (volume ratio 1:1) at 50℃ for 5 minutes;

[0074] 4. The surface-treated stainless steel pipe 1 and reinforced carbon steel pipe 2 are threaded together to form a composite pipe blank;

[0075] 5. Fill the composite tube blank with water. After the tube is filled with water, seal the ends of the tube.

[0076] 6. Apply lubricant to the outer surface of the reinforced carbon steel pipe 2 of the composite pipe blank for water injection, and then draw and reduce the diameter. After the drawing and reduction is completed, the composite pipe is obtained.

[0077] 7. Cut off the welded parts at both ends of the composite pipe to drain the water, and clean and dry the inner and outer surfaces of the composite pipe to obtain a high corrosion-resistant stainless steel-lined composite pipe.

[0078] Example 4:

[0079] like Figure 2 As shown, a manufacturing process for a high corrosion-resistant stainless steel-lined composite pipe includes the following steps:

[0080] 1. Duplex stainless steel is selected for rolling and welding to obtain stainless steel pipe 1;

[0081] 2. Laser drilling is performed on the two welding surfaces of the low carbon steel plate, followed by rolling. Tin powder and powdered molybdenum disulfide mixture 7 are spread on one of the welding surfaces and then welded to obtain reinforced carbon steel pipe 2.

[0082] 3. Alkali washing is performed on both the inner and outer parts of stainless steel pipe 1 and reinforced carbon steel pipe 2: immersion in 6wt% potassium hydroxide solution at 55℃ for 8 minutes; acid washing: immersion in 70wt% hydrochloric acid solution at 40℃ for 15 minutes; sandblasting cleaning, with a cleaning grade of Sa2.5; secondary acid washing: immersion in 15wt% sulfuric acid solution at 48℃ for 8 minutes.

[0083] 4. The surface-treated stainless steel pipe 1 and reinforced carbon steel pipe 2 are threaded together to form a composite pipe blank;

[0084] 5. Fill the composite tube blank with water. After the tube is filled with water, seal the ends of the tube.

[0085] 6. Apply lubricant to the outer surface of the reinforced carbon steel pipe 2 of the composite pipe blank for water injection, and then draw and reduce the diameter. After the drawing and reduction is completed, the composite pipe is obtained.

[0086] 7. Cut off the welded parts at both ends of the composite pipe to drain the water, and clean and dry the inner and outer surfaces of the composite pipe to obtain a high corrosion-resistant stainless steel-lined composite pipe.

[0087] Comparative Example 1:

[0088] A manufacturing process for a highly corrosion-resistant stainless steel-lined composite pipe includes the following steps:

[0089] 1. Austenitic stainless steel is selected for rolling and welding to obtain stainless steel pipe 1;

[0090] 2. The low-carbon steel sheet is rolled, and after spreading tin powder and powdered molybdenum disulfide mixture 7 on one of the welding surfaces, it is welded to obtain reinforced carbon steel pipe 2.

[0091] 3. Alkali washing is performed on both the inner and outer surfaces of stainless steel pipe 1 and reinforced carbon steel pipe 2: immersion in 5wt% sodium hydroxide solution at 40℃ for 10 minutes; acid washing: immersion in 10wt% sulfuric acid solution at 40℃ for 15 minutes; sandblasting cleaning, with a cleaning grade of Sa2; secondary acid washing: immersion in 10wt% sulfuric acid solution at 45℃ for 10 minutes.

[0092] 4. The surface-treated stainless steel pipe 1 and reinforced carbon steel pipe 2 are threaded together to form a composite pipe blank;

[0093] 5. Fill the composite tube blank with water. After the tube is filled with water, seal the ends of the tube.

[0094] 6. Apply lubricant to the outer surface of the reinforced carbon steel pipe 2 of the composite pipe blank for water injection, and then draw and reduce the diameter. After the drawing and reduction is completed, the composite pipe is obtained.

[0095] 7. Cut off the welded parts at both ends of the composite pipe to drain the water, and clean and dry the inner and outer surfaces of the composite pipe to obtain a high corrosion-resistant stainless steel-lined composite pipe.

[0096] Comparative Example 2:

[0097] A manufacturing process for a highly corrosion-resistant stainless steel-lined composite pipe includes the following steps:

[0098] 1. Martensitic stainless steel is selected for rolling and welding to obtain stainless steel pipe 1;

[0099] 2. Laser drilling is performed on the two welding surfaces of the low carbon steel plate, followed by rolling. Tin powder is spread on one of the welding surfaces and then welded to obtain reinforced carbon steel pipe 2.

[0100] 3. Alkali washing of both the inner and outer surfaces of stainless steel pipe 1 and reinforced carbon steel pipe 2: Immersion in 10wt% sodium hydroxide solution at 50℃ for 3 minutes; Acid washing: Immersion in a mixture of 10wt% sulfuric acid solution and 50wt% hydrochloric acid solution (volume ratio 1:1) at 45℃ for 10 minutes; Sandblasting cleaning, with a cleaning grade of Sa2; Secondary acid washing: Immersion in a mixture of 10wt% sulfuric acid solution and 50wt% hydrochloric acid solution (volume ratio 1:1) at 50℃ for 5 minutes;

[0101] 4. The surface-treated stainless steel pipe 1 and reinforced carbon steel pipe 2 are threaded together to form a composite pipe blank;

[0102] 5. Fill the composite tube blank with water. After the tube is filled with water, seal the ends of the tube.

[0103] 6. Apply lubricant to the outer surface of the reinforced carbon steel pipe 2 of the composite pipe blank for water injection, and then draw and reduce the diameter. After the drawing and reduction is completed, the composite pipe is obtained.

[0104] 7. Cut off the welded parts at both ends of the composite pipe to drain the water, and clean and dry the inner and outer surfaces of the composite pipe to obtain a high corrosion-resistant stainless steel-lined composite pipe.

[0105] Comparative Example 3:

[0106] A manufacturing process for a highly corrosion-resistant stainless steel-lined composite pipe includes the following steps:

[0107] 1. Ferritic stainless steel is selected for rolling and welding to obtain stainless steel pipe 1;

[0108] 2. Low-carbon steel plates are rolled and welded to obtain reinforced carbon steel pipe 2;

[0109] 3. Alkali washing is performed on both the inner and outer surfaces of stainless steel pipe 1 and reinforced carbon steel pipe 2: immersion in 9wt% potassium hydroxide solution at 42℃ for 7 minutes; acid washing: immersion in 60wt% hydrochloric acid solution at 44℃ for 11 minutes; sandblasting cleaning, with a cleaning grade of Sa2.5; secondary acid washing: immersion in 14wt% sulfuric acid solution at 49℃ for 6 minutes.

[0110] 4. The surface-treated stainless steel pipe 1 and reinforced carbon steel pipe 2 are threaded together to form a composite pipe blank;

[0111] 5. Fill the composite tube blank with water. After the tube is filled with water, seal the ends of the tube.

[0112] 6. Apply lubricant to the outer surface of the reinforced carbon steel pipe 2 of the composite pipe blank for water injection, and then draw and reduce the diameter. After the drawing and reduction is completed, the composite pipe is obtained.

[0113] 7. Cut off the welded parts at both ends of the composite pipe to drain the water, and clean and dry the inner and outer surfaces of the composite pipe to obtain a high corrosion-resistant stainless steel-lined composite pipe.

[0114] Performance testing:

[0115] The corrosion potential and corrosion current of the prepared stainless steel composite pipe were tested using an electrochemical workstation to effectively evaluate the corrosion resistance of the stainless steel composite pipe, as shown in Table 1.

[0116] Using a material testing machine, the interfacial bonding strength of the prepared stainless steel composite pipe was determined at a tensile rate of 3.0 mm / min. At the same time, the clamping force of the prepared stainless steel composite pipe was also determined. The interfacial bonding performance of the stainless steel composite pipe was effectively evaluated in summary, as shown in Table 2.

[0117] Table 1. Corrosion resistance test results of the high corrosion-resistant stainless steel-lined composite pipes prepared in the examples and comparative examples.

[0118]

[0119] Table 2. Test results of interfacial bonding performance of the high corrosion-resistant stainless steel-lined composite pipes prepared in the examples and comparative examples.

[0120]

[0121] As shown in Tables 1 and 2, the corrosion resistance and interfacial bonding performance of Examples 1-4 are better than those of Comparative Examples 1-3.

[0122] This is because, in Examples 1-4, three microchannel structures were laser-drilled on the two welding surfaces of the carbon steel sheet. During welding, the microchannel structures in the three regions, as well as the space between the two welding surfaces, were filled with a mixture of molten tin powder and powdered molybdenum disulfide. As the temperature decreased and cooled, the molten tin powder mixed with powdered molybdenum disulfide rapidly cooled and solidified, forming a uniform and dense mechanical interlocking structure without cracks, pores, or gaps in the microchannel structures in the three regions and between the two welding surfaces. Furthermore, the welded area exhibited corrosion resistance against acids and alkalis, thus resulting in a reinforced carbon steel pipe without weld cracks or gaps.

[0123] Using reinforced carbon steel pipe as the outer layer and stainless steel pipe as the inner layer, a high corrosion-resistant stainless steel-lined composite pipe was produced through a production technique combining drawing and diameter reduction with water injection pressurization. This stainless steel composite pipe exhibits high interfacial bonding strength, with no weak points forming at the interface that could reduce overall bonding strength. Furthermore, when subjected to external forces such as pressure and tension, the stainless steel composite pipe is less prone to crack propagation, significantly enhancing its corrosion resistance and extending its service life.

[0124] In Comparative Example 1, since no holes were drilled, even though a mixture of tin powder and powdered molybdenum disulfide 7 was laid between the two welding surfaces, a uniform and dense mechanical interlocking structure without cracks, pores, or gaps could not be formed. Therefore, the corrosion resistance and interfacial bonding strength of the stainless steel composite pipe were relatively weak.

[0125] In Comparative Example 2, since molybdenum disulfide was not added, the distribution of molten tin powder in the microchannel structure of the three regions and between the two welding surfaces was not uniform and dense enough, and the corrosion resistance of the welding area against acid and alkali was not strong enough. However, it could form a mechanical interlocking structure. Therefore, the corrosion resistance and interfacial bonding strength of the stainless steel composite pipe obtained in the end were better than those of Comparative Example 1.

[0126] Comparative Example 3 had neither drilling nor the addition of tin powder and powdered molybdenum disulfide mixture 7, resulting in the stainless steel composite pipe with the worst corrosion resistance and interfacial bonding strength.

[0127] The above results demonstrate and describe the basic principles and main features of this application, as well as its advantages.

[0128] Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this application. Various changes and modifications can be made to this application without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of this application as claimed. The scope of protection of this application is defined by the equivalents of the appended claims.

Claims

1. A high corrosion-resistant stainless steel-lined composite pipe, characterized in that, The structure includes an inner stainless steel tube (1) and an outer reinforced carbon steel tube (2); the stainless steel tube (1) and the reinforced carbon steel tube (2) are combined by drawing and reducing diameter and then injecting water to pressurize; each of the two welding surfaces of the reinforced carbon steel tube (2) is provided with a first microchannel region (3) located at the edge of the welding surface and a second microchannel region (4) located in the middle of the welding surface; the first microchannel region (3) is provided with a plurality of first microchannels (5), and the second microchannel region (4) is provided with a plurality of second microchannels (6), the channel size of the first microchannel (5) is larger than the channel size of the second microchannel (6); one of the two welding surfaces of the reinforced carbon steel tube (2) A layer of tin powder and powdered molybdenum disulfide mixture (7) is spread on the welding surface of the reinforced carbon steel pipe (2); the microchannel structure on the welding surface of the reinforced carbon steel pipe (2) is obtained by laser drilling; the channel dimensions include channel width and channel depth; the channel width of the first microchannel (5) is 3~5mm and the depth is 1.0~1.5cm; the channel width of the second microchannel (6) is 1~2mm and the depth is 0.5~0.8cm; the mass ratio of the tin powder and powdered molybdenum disulfide mixture (7) is (65~85):(15~35); the thickness of the layer of tin powder and powdered molybdenum disulfide mixture (7) spread on the welding surface of the reinforced carbon steel pipe (2) is 1.0~2.0mm.

2. The manufacturing process of a high corrosion-resistant stainless steel-lined composite pipe according to claim 1, characterized in that, Includes the following steps: Stainless steel strip is rolled and welded to obtain stainless steel pipe (1); Laser drilling was performed on the two welding surfaces of the carbon steel plate, followed by rolling. A mixture of tin powder and powdered molybdenum disulfide (7) was laid on one of the welding surfaces and then welded to obtain a reinforced carbon steel pipe (2). The inner and outer surfaces of the obtained stainless steel pipe (1) and reinforced carbon steel pipe (2) are both surface treated; The surface-treated stainless steel pipe (1) and reinforced carbon steel pipe (2) are assembled into a composite pipe blank. Water is injected into the composite tube blank. After the tube is filled with water, the ends of the tube are sealed by welding. Lubricant was applied to the outer surface of the reinforced carbon steel pipe (2) of the composite pipe blank to be injected with water, and then the pipe was drawn and reduced in diameter. After the drawing and reduction of diameter was completed, the composite pipe was obtained. The welded portions at both ends of the composite pipe are removed to drain the water. The inner and outer surfaces of the composite pipe are cleaned and dried to obtain a high corrosion-resistant stainless steel-lined composite pipe.

3. The preparation process of a high corrosion-resistant stainless steel-lined composite pipe according to claim 2, characterized in that, The thickness of the stainless steel pipe (1) is 2~3mm; the thickness of the reinforced carbon steel pipe (2) is 15.0~25.0mm.

4. The preparation process of a high corrosion-resistant stainless steel-lined composite pipe according to claim 2, characterized in that, The surface treatment includes alkaline washing, acid washing, sandblasting, and secondary acid washing.

5. The manufacturing process of a high corrosion-resistant stainless steel-lined composite pipe according to claim 4, characterized in that, The alkaline washing involves immersing the patient in a 5-10 wt% sodium hydroxide or potassium hydroxide solution at 40-55°C for 3-10 minutes.

6. The preparation process of a high corrosion-resistant stainless steel-lined composite pipe according to claim 4, characterized in that, The pickling process uses a 10-15 wt% sulfuric acid solution, a 50-70 wt% hydrochloric acid solution, or a mixture of both, and is performed at 40-45°C for 10-15 minutes. The secondary pickling process uses a 10-15 wt% sulfuric acid solution, a 50-70 wt% hydrochloric acid solution, or a mixture of both, and is performed at 45-50°C for 5-10 minutes.

7. The preparation process of a high corrosion-resistant stainless steel-lined composite pipe according to claim 4, characterized in that, The sandblasting cleaning grade is Sa2 or Sa2.

5.

8. The preparation process of a high corrosion-resistant stainless steel-lined composite pipe according to claim 2, characterized in that, The lubricant includes at least one of synthetic ester lubricants and polyether lubricants.

Images