High-frequency induction welding repair method and device for stainless steel lining

Abstract

The invention discloses a high-frequency induction welding repair method and device for a stainless steel lining, and the method comprises the following steps: S1, forming a tubular steel strip with an opening angle, and pre-cleaning the tubular steel strip; s2, mounting and debugging before welding: mounting an induction coil, a tubular steel belt, an extrusion roller and an impedor; adjusting the position of an induction coil, calibrating the opening angle of the tubular steel strip, and calibrating the pressure of an extrusion roller; s3, high-frequency induction welding is conducted, specifically, metal in the opening corner area of the tubular steel strip is molten through heat generated by a high-frequency power source, the molten metal is fused with the opening corner to form a weld joint, and then a welded steel pipe is formed; and S4, post-treatment and welding quality detection are conducted, specifically, burrs at the welding seam are cut off, and nondestructive testing and mechanical property and corrosion resistance testing are conducted to confirm the welding seam quality. The method has the advantages of efficient repair, high-quality weld joints and low-cost welding.

Description

Technical Field

[0001] The present invention relates to the technical field of welding part repair, and in particular to a high-frequency induction welding repair method and device for a stainless steel inner lining. Background Art

[0002] Traditional welding repair methods include patch welding, argon arc welding, laser welding, etc. These welding repair methods are often used for stainless steel pipe repair, but they have disadvantages such as large heat input, grain coarsening, and poor corrosion resistance; moreover, these welding repair methods also have a slow welding speed (usually <10 m / min), low efficiency, and are difficult to meet the large-scale repair requirements. In addition, a large heat affected zone, easy burn-through or deformation of thin walls, and defects such as spatter and pores easily generated in the weld are also problems that cannot be ignored in this type of welding method.

[0003] Compared with traditional welding, high-frequency induction welding (HFIW) has its unique advantages, but most of them focus on thick-walled pipes or ordinary stainless steels and have poor adaptability to thin walls; for example, when the wall thickness <0.5 mm, incomplete fusion or burn-through is often caused by mismatched heat input; in addition, there is a lack of research on the formation mechanism of defects such as humps and spatter, and process parameters (such as opening angle, cleanliness, etc.) have not been systematically optimized.

[0004] The statements here only provide background art related to the present invention and do not necessarily constitute prior art. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-frequency induction welding repair method and device for a stainless steel inner lining, and through optimizing process parameters and equipment configuration, to achieve efficient and defect-free pipe repair.

[0006] To achieve the above purpose, the present invention provides a high-frequency induction welding repair method for a stainless steel inner lining, including:

[0007] Step S1, forming a tubular steel strip with an opening angle and pre-cleaning the tubular steel strip;

[0008] Step S2, installation and debugging before welding: including sleeving an induction coil in the area of the tubular steel strip close to the opening angle, symmetrically arranging extrusion rollers on both sides of the opening angle of the tubular steel strip, and arranging an impedance device in the area close to the opening angle; and adjusting the position of the induction coil, calibrating the opening angle of the tubular steel strip, and calibrating the extrusion roller pressure;

[0009] Step S3, high-frequency induction welding: exciting the high-frequency magnetic field of the induction coil through a high-frequency power supply, so that the metal in the opening angle area of the tubular steel strip generates molten metal after being heated by resistance heat, and the molten metal fuses the opening angle to form a weld seam, and then a welded steel pipe is formed;

[0010] Step S4, Post-treatment and Weld Quality Inspection: After the welded steel pipe cools naturally, remove the burrs at the weld, and perform non-destructive testing, mechanical property and corrosion resistance tests to confirm the weld quality.

[0011] Optionally, step S1 includes:

[0012] S1.1, The steel strip passes through multiple cold rolling dies in sequence, is gradually bent into a tubular shape, and the opening angle of the tubular steel strip is adjusted;

[0013] S1.2, Clean the edges of the tubular steel strip to make it free of moisture, oil and oxide residues.

[0014] Optionally, in S1.1, the opening angle is adjusted to 4.5° - 6.5°; the opening angle is V-shaped; the opening angle is distributed at the plate connection of the tubular steel strip after cold rolling.

[0015] Optionally, step S2 includes:

[0016] S2.1, Adjust the vertical distance between the inner surface of the induction coil and the outer surface of the tubular steel strip to ensure that the magnetic field evenly covers the welding area;

[0017] S2.2, Use an angle measuring instrument to measure the opening angle of the tubular steel strip, and calibrate it through the mechanical force of the angle measuring instrument and the forming roller die;

[0018] S2.3, Set the extrusion roller pressure through a pressure sensor to ensure that the molten metal in the opening angle area is evenly extruded during welding.

[0019] Optionally, in step S2.1, the vertical distance between the inner surface of the induction coil and the outer surface of the tubular steel strip is adjusted to 1 - 3 mm;

[0020] In step S2.2, the angle of the opening angle is calibrated to 6° ± 0.5°;

[0021] In step S2.3, the pressure of the extrusion roller is set to 5 - 15 MPa.

[0022] Optionally, step S3 includes:

[0023] S3.1, Start the high-frequency power supply, and the current generates a high-frequency magnetic field through the induction coil; and control the heat input value generated by the high-frequency power supply;

[0024] S3.2, Control the tubular steel strip to move along its axial direction, that is, away from the opening angle direction, so that the tubular steel strip passes through the welding area at a constant speed, and then a weld is formed;

[0025] S3.3. Monitor the output power of the high-frequency power supply and the pressure of the squeezing roller in real time, and adjust the welding parameters, including output power, welding speed, squeezing roller pressure, and the degree of the opening angle, in combination with the defect suppression model to predict and reduce the generation of welding defects;

[0026] S3.4. As the tubular steel strip runs at a constant speed, the molten metal in the opening angle area is gathered and welded under the pressure of the squeezing roller, and continuous burrs are generated after welding.

[0027] Optionally, in the step S3.1, the heat input value is 14 - 19 kJ / m;

[0028] In the step S3.2, the welding speed of the tubular steel strip is 70 - 90 m / min.

[0029] Optionally, the monitoring is implemented through a feedback control algorithm. Specifically, this algorithm automatically adjusts the high-frequency power supply power, welding speed, and squeezing roller pressure of the welding according to the length of the molten metal area formed during the welding process.

[0030] Optionally, the step S4 includes:

[0031] S4.1. The welded steel pipe is cooled naturally by air to avoid the generation of residual stress;

[0032] S4.2. Observe the morphology of the burrs; and observe the microstructure of the metal in the weld zone through SEM, and then remove the burrs;

[0033] S4.3. Test the hardness, tensile strength, and corrosion resistance of the metal in the weld zone.

[0034] The present invention also provides a high-frequency induction welding repair device for a stainless steel lining, including:

[0035] An induction coil, which is arranged around the opening angle area of the tubular steel strip and is electrically connected to the high-frequency power supply to generate an alternating magnetic field through high-frequency current, and then generate resistance heat to melt the metal in the opening angle area of the tubular steel strip;

[0036] Two squeezing rollers, which are symmetrically arranged on both sides of the opening angle of the tubular steel strip to squeeze the molten metal from both sides to the middle, so that the molten metal welds the opening angle and forms a weld;

[0037] An impedance device, which is arranged inside the tubular steel strip near the opening angle to guide the current generated by the magnetic field to concentrate on the opening angle.

[0038] In summary, compared with the prior art, the present invention has the following beneficial effects:

[0039] 1. A high-frequency induction welding repair method and device for a stainless steel lining. In terms of process parameter optimization, the optimal parameter combination (opening angle of 6° and heat input of 16.5 kJ / m) is determined through experiments, making the weld microstructure fine-grained austenite + δ-ferrite, with a tensile strength of 920 MPa and a hardness of 289 HV, and its comprehensive performance is significantly higher than that of the base material.

[0040] 2. A high-frequency induction welding repair method and device for a stainless steel lining. By designing an asymmetric induction coil, matching the rib distribution, and optimizing the current path, the energy loss is reduced, and the welding repair speed is increased by 8 times compared with traditional argon arc welding.

[0041] 3. A high-frequency induction welding repair method and device for a stainless steel lining. Based on the molten metal flow balance theory (dynamic balance of surface tension and static pressure), a defect prediction model is established, making the weld free of hump and splash defects, and realizing real-time feedback adjustment of process parameters. Brief Description of the Drawings

[0042] Figure 1 is the high-frequency induction welding flow chart of the present invention;

[0043] Figure 2 is the schematic diagram of the high-frequency induction welding device of the present invention. Detailed Embodiment

[0044] The following will further elaborate on the present invention through preferred embodiments in conjunction with the attached Figures 1 - 2 , and the advantages and features of the present invention will be clearer according to the following description. It should be noted that the drawings are in a very simplified form and all use non-precise scales, only for conveniently and clearly assisting in explaining the purpose of the embodiments of the present invention. In order to make the purpose, features, and advantages of the present invention more obvious and understandable, please refer to the drawings. It should be known that the structures, ratios, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention. Therefore, they do not have technical essential significance. Any modification of the structure, change of the ratio relationship, or adjustment of the size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope covered by the technical content disclosed in the present invention.

[0045] The present invention provides a high-frequency induction welding device for repairing the lining of stainless steel, which is used for welding and repairing the continuous V-shaped opening angle 201 area formed at the connection of the tubular steel strip 200 after cold rolling, as Figure 2As shown in the figure, the high-frequency induction welding device includes: an induction coil 100, which is disposed around the opening angle 201 area of the tubular steel strip 200 and is electrically connected to a high-frequency power supply to generate an alternating magnetic field through a high-frequency current, thereby generating resistance heat to melt the metal in the opening angle 201 area of the tubular steel strip 200; two squeezing rollers 300, symmetrically arranged on both sides of the opening angle 201 of the tubular steel strip 200 to squeeze the molten metal from both sides to the middle, so that the molten metal welds the opening angle 201 and forms a weld seam 500; an impedance device 400, disposed inside the tubular steel strip 200 near the opening angle 201 to guide the current generated by the magnetic field to concentrate on the opening angle 201; a cooling system, disposed around the induction coil 100 and the squeezing rollers 300 to cool down the device.

[0046] In a specific embodiment of the present invention, the tubular steel strip 200 is 316 austenitic stainless steel; the outer diameter of the tubular steel strip 200 is 8 mm.

[0047] Among them, the spacing distance of the induction coil 100 around the opening angle 201 of the tubular steel strip 200 is adjustable, and the adjustment range is 1-3 mm.

[0048] Preferably, the surface of the squeezing roller 300 is plated with hard chromium to enhance wear resistance.

[0049] Preferably, the impedance device 400 is made of ferrite or graphite material to be heat-resistant and not interfere with the magnetic field.

[0050] Preferably, the cooling system is cooled by spraying water or air cooling.

[0051] In addition, the high-frequency induction welding device further includes an auxiliary system, which includes: a steel strip forming unit, a cleaning device and a monitoring system; the steel strip forming unit is provided with multiple cold rolling dies to gradually bend a flat steel strip into a tubular steel strip 200; the cleaning device is a jet or ultrasonic cleaning device for removing oil stains, oxides and residual water stains on the surface of the tubular steel strip 200; the monitoring system includes an infrared thermometer and a laser speedometer, wherein the infrared thermometer is used to monitor the welding temperature, and the laser speedometer is used to feedback the welding speed in real time.

[0052] The present invention also provides a repair method for a thin-walled ribbed stainless steel inner lining by high-frequency induction welding, which is used for welding and repairing the opening angle 201 area of the tubular steel strip 200, as Figure 1 shown, the welding repair method includes the following steps:

[0053] S1, forming a tubular steel strip 200 with an opening angle 201 and pre-cleaning the tubular steel strip 200;

[0054] S2, Installation and debugging before welding: including sleeving the induction coil 100 on the outer area of the tubular steel strip 200 near the opening angle 201, symmetrically arranging the extrusion rollers 300 on both sides of the opening angle 201 of the tubular steel strip 200, and arranging the impedance device 400 near the opening angle 201, that is, the area to be welded; furthermore, adjusting the position of the induction coil 100, calibrating the opening angle 201 of the tubular steel strip 200, and calibrating the pressure of the extrusion rollers 300;

[0055] S3, High-frequency induction welding: Through the high-frequency magnetic field of the induction coil 100 excited by the high-frequency power supply, the metal in the area of the opening angle 201 of the tubular steel strip 200 generates molten metal after being heated by resistance heat, and the molten metal forms a welded steel pipe after hot welding, that is, the tubular steel strip 200 without the opening angle 201;

[0056] S4, Post-treatment and welding quality inspection: After the welded steel pipe is naturally cooled, the burrs at the weld 500 are removed, and non-destructive testing, mechanical properties and corrosion resistance tests are carried out to confirm the quality of the weld 500.

[0057] Furthermore, the step S1 includes:

[0058] S1.1, The steel strip passes through multiple cold rolling dies in sequence, is gradually bent into a tubular shape, and the opening angle 201 of the tubular steel strip 200 is adjusted to 4.5° - 6.5°;

[0059] Among them, the opening angle 201 is V-shaped; and the opening angle 201 is distributed at the plate connection of the tubular steel strip 200 after cold rolling; the outer diameter of the bent tubular steel strip 200 is 8 mm.

[0060] Among them, the bending angle of each cold rolling die is set to 2 - 5°, and the pressure range of rolling is 15 - 30 MPa.

[0061] It should be noted that when the opening angle 201 is less than 4.5°, hump defects will occur during welding; when the opening angle 201 is greater than 6.5°, insufficient molten metal and discontinuous burrs will be caused during welding.

[0062] In the best embodiment of the present invention, when the opening angle 201 is 6°, the welding quality is the best.

[0063] S1.2, Wipe the edge of the tubular steel strip 200 with anhydrous ethanol or blow it with high-pressure gas to make it free of moisture, oil stains and oxide residues.

[0064] Furthermore, the step S2 includes:

[0065] S2.1, Adjust the vertical distance between the inner surface of the induction coil 100 and the outer surface of the tubular steel strip 200 to 1 - 3 mm to ensure that the magnetic field evenly covers the welding area;

[0066] In a specific embodiment of the present invention, the vertical distance between the inner surface of the induction coil 100 and the outer surface of the tubular steel strip 200 is adjusted to 1.5 mm;

[0067] S2.2, Use an angle measuring instrument to measure the opening angle 201 of the tubular steel strip 200, and calibrate it to 6° ± 0.5° through the mechanical force of the angle measuring instrument and the forming roll pressing die;

[0068] S2.3, Set the pressure of the extrusion roll 300 to 5 - 15 MPa through a pressure sensor to ensure that the molten metal in the opening angle 201 area is evenly extruded during welding;

[0069] It should be noted that when the set value of the pressure of the extrusion roll 300 is less than 5 MPa, there will be insufficient pressure, resulting in oxide residues after welding; when the set value of the pressure of the extrusion roll 300 is greater than 15 MPa, there will be excessive pressure, resulting in deformation of the weld 500 formed by welding.

[0070] In the best embodiment of the present invention, when the set value of the pressure of the extrusion roll 300 is in the range of 5 - 10 MPa, the welding quality is the best.

[0071] Furthermore, the step S3 includes:

[0072] S3.1, Start the high-frequency power supply, and the current passes through the induction coil 100 to generate a high-frequency magnetic field; and control the heat input value generated by the high-frequency power supply to be 14 - 19 kJ / m;

[0073] Among them, the working frequency of the high-frequency power supply is 400 kHz, its output power is 22 kW, and the current stability of the high-frequency power supply needs to be controlled within a fluctuation range of ±2%. In the best embodiment of the present invention, the heat input value generated by the high-frequency power supply is 16.5 kJ / m, and the welding quality is the best.

[0074] S3.2, Control the tubular steel strip 200 to move along its axial direction, that is, away from the opening angle 201, through a servo motor, so that the tubular steel strip 200 passes through the welding area at a welding speed of 70 - 90 m / min at a constant speed, thereby forming a weld 500;

[0075] It should be noted that when the welding speed is less than 70 m / min, the heat input generated by the high-frequency power supply is too high, resulting in coarsening of the metal grains at the weld 500; when the welding speed is greater than 90 m / min, the heat input generated by the high-frequency power supply is too low, and there is insufficient molten metal, resulting in incomplete welding of the weld 500.

[0076] In the best embodiment of the present invention, when the welding speed is 80 m / min, the welding quality is the best.

[0077] S3.3. Use the feedback control (PID) algorithm to monitor the output power of the high-frequency power supply and the pressure of the squeezing roller 300 in real time, and adjust the welding parameters through the defect suppression model, including the output power, welding speed, pressure of the squeezing roller 300, and the degree of the opening angle 201, to predict and reduce the generation of welding defects;

[0078] Specifically, the feedback control (PID) algorithm automatically adjusts the high-frequency power supply power, welding speed, and pressure of the squeezing roller 300 according to the length of the molten metal area formed during the welding process; further, the high-frequency power supply power is controlled within 22kW ± 10%; the welding speed is controlled within (70 - 90) ± 5m / min; the pressure of the squeezing roller 300 is controlled within (5 - 15) ± 2MPa.

[0079] The defect suppression model includes hump defect control and spatter defect control.

[0080] Among them, the formation mechanism of the hump defect is as follows: when the opening angle 201 is too small, the molten metal in the opening angle 201 area ejects unstably and solidifies to form an ellipsoidal protrusion; in this case, calibrate the opening angle 201 to 6° ± 0.5° to extend the stable time of the molten metal, or optimize the pressure of the squeezing roller 300 to control the hump defect. The formation mechanism of the spatter defect is as follows: the water stains remaining on the tubular steel strip 200 are prone to explode at high temperatures, resulting in spatter of the molten metal; in this case, through the drying process before welding (such as infrared drying), or regularly checking the cleaning device to control the spatter defect.

[0081] Therefore, when the defect suppression model detects a hump defect, increase the opening angle 201 to 6° ± 0.5° and reduce the welding speed to compensate for the heat input; when the defect suppression model detects water stain spatter, blow and dry the welding area, and then weld after a short stay (0.5s).

[0082] In the specific embodiment of the present invention, the welding process parameters are also verified, and the verification results are shown in Table 1 below:

[0083] Table 1. Verification of process parameters (optimized by orthogonal test L9(34))

[0084]

[0085]

[0086] Further, the control of the opening angle 201 for hump defects and spatter defects is shown in Table 2 below:

[0087] Table 2. Control of hump defects and splash defects by opening angle (n = 100 pieces, each 1 m long)

[0088]

[0089] S3.4, and then as the tubular steel strip 200 runs at a constant speed, the molten metal in the opening angle 201 area is gathered and welded under the pressure of the squeezing roller 300, and there are continuous burrs after welding.

[0090] Further, the step S4 includes:

[0091] S4.1, the welded steel pipe is naturally cooled by air to avoid the generation of residual stress;

[0092] S4.2, observing the morphology of the burrs (whether continuous, without bifurcation or humps) through a stereomicroscope; and observing the microstructure of the metal in the weld 500 area through SEM (scanning electron microscope), and then removing the burrs using a mechanical tool;

[0093] In a specific embodiment of the present invention, a ZOOM-860C type stereomicroscope is used; further, the metallographic specimen is prepared through the processes of cutting → embedding → grinding → polishing → etching, and it is observed through SEM that fine strip-shaped δ-ferrite is distributed on the austenite matrix of the metallographic specimen, that is, there is grain boundary precipitation; among them, 2 mL of glycerol, 2 mL of nitric acid, and 4 mL of hydrofluoric acid are used in the etching process, and it is etched in an acidic environment for 30 s.

[0094] S4.3, testing the hardness, tensile strength, and corrosion resistance of the metal in the weld 500 area.

[0095] Specifically, under the conditions of a load of 1 N and a holding time of 10 s, the hardness test is carried out through Vickers hardness, and the test results are shown in Table 3 below:

[0096] Table 3. Microhardness (HV0.5, GB / T 4340.1-2021)

[0097]

[0098] The hardness test results show that the average hardness of the weld 500 area is 289 HV.

[0099] Specifically, samples are prepared according to GB / T 228.1-2010, and the tensile strength test of the welded joint is carried out, and the test results are shown in Table 4 below:

[0100] Table 4. Tensile strength (GB / T 228.1-2021)

[0101]

[0102] The tensile strength test results show that: when preparing specimens according to GB / T 228.1-2010, the tensile strength of the welded joint is ≥920 MPa.

[0103] Specifically, in accordance with the ASTM B117-23 standard, the corrosion resistance test of the welded steel pipe specimens was carried out under 3000 h salt spray, and the test results are shown in Table 5 below:

[0104] Table 5. Corrosion Resistance Test (ASTM B117-23, 3000 h Salt Spray)

[0105]

[0106]

[0107] The corrosion resistance test results show that: in accordance with the ASTM B117-23 standard, under 3000 h salt spray, the corrosion rate in the 500 area of the weld is 0.008 mm / year, which is 33% lower than that of the base metal.

[0108] In summary, a high-frequency induction welding repair method and device with a stainless steel lining provided by the present invention have the advantages of efficient repair, high-quality welds, and low-cost welding; specifically, the welding speed of the present invention reaches 80 m / min, which is 8 times higher than that of traditional argon arc welding; the tensile strength, hardness, and corrosion resistance of the weld area are significantly higher than those of the base metal, and there are no humps and splashes; in addition, no welding materials are required, the energy consumption is reduced by 30%, and the single repair cost is reduced by 40%.

[0109] It should be noted that in this article, the terms "including", "comprising" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of another identical element in the process, method, article or device including the said element.

[0110] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "height", "thickness", "upper", "lower", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, 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 the description of the present invention, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0111] In the description of the present invention, unless otherwise clearly defined and limited, the terms "mounted", "connected", "coupled", "fixed" shall be construed broadly. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0112] In the present invention, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature may include the 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 in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely indicates that the horizontal height of the first feature is lower than that of the second feature.

[0113] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation to the present invention. After those skilled in the art have read the above content, various modifications and alternatives to the present invention will be obvious. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims

1. A high-frequency induction welding repair method for a stainless steel inner lining, characterized in that, It includes the following steps: Step S1, forming a tubular steel strip (200) with an opening angle (201), and pre-cleaning the tubular steel strip (200); Step S2, installation and debugging before welding: including sleeving an induction coil (100) in the area of the tubular steel strip (200) near the opening angle (201), symmetrically arranging extrusion rollers (300) on both sides of the opening angle (201) of the tubular steel strip (200), and arranging an impedance device (400) in the area near the opening angle (201); and adjusting the position of the induction coil (100), calibrating the opening angle (201) of the tubular steel strip (200), and calibrating the pressure of the extrusion rollers (300); Step S3, high-frequency induction welding: exciting the high-frequency magnetic field of the induction coil (100) through a high-frequency power supply, so that the metal in the area of the opening angle (201) of the tubular steel strip (200) generates molten metal after being heated by resistance heat, and the molten metal fuses the opening angle (201) to form a weld seam (500), thereby forming a welded steel pipe; Step S4, post-treatment and welding quality inspection: after the welded steel pipe is naturally cooled, removing the burrs at the weld seam (500), and performing non-destructive testing, mechanical property and corrosion resistance tests to confirm the quality of the weld seam (500).

2. The high-frequency induction welding repair method according to claim 1, characterized in that The step S1 includes: S1.1, the steel strip passes through multiple cold rolling dies in sequence, is gradually bent into a tubular shape, and the opening angle (201) of the tubular steel strip (200) is adjusted; S1.2, cleaning the edge of the tubular steel strip (200) to make it free of moisture, oil and oxide residues.

3. The high-frequency induction welding repair method according to claim 2, characterized in that In the S1.1, the opening angle is adjusted to 4.5° - 6.5°; the opening angle (201) is V-shaped; the opening angle (201) is distributed at the joint of the plates of the tubular steel strip (200) after cold rolling.

4. The high-frequency induction welding repair method according to claim 1, wherein, The step S2 includes: S2.1, adjusting the vertical distance between the inner surface of the induction coil (100) and the outer surface of the tubular steel strip (200) to ensure that the magnetic field uniformly covers the welding area; S2.2, using an angle measuring instrument to measure the opening angle (201) of the tubular steel strip (200), and calibrating it through the mechanical force of the angle measuring instrument and the forming roller die; S2.3, setting the pressure of the extrusion rollers (300) through a pressure sensor to ensure that the molten metal in the area of the opening angle (201) is evenly extruded during welding.

5. The high-frequency induction welding repair method according to claim 4, wherein In the step S2.1, the vertical distance between the inner surface of the induction coil (100) and the outer surface of the tubular steel strip (200) is adjusted to 1 - 3 mm; In the step S2.2, the angle of the opening angle (201) is calibrated to 6° ± 0.5°; In the step S2.3, the pressure of the extrusion rollers (300) is set to 5 - 15 MPa.

6. The high-frequency induction welding repair method according to claim 1, characterized in that, The step S3 includes: S3.1, starting the high-frequency power supply, and generating a high-frequency magnetic field when the current passes through the induction coil (100); and controlling the heat input value generated by the high-frequency power supply; S3.2, controlling the tubular steel strip (200) to move along its axial direction, that is, in the direction away from the opening angle (201), so that the tubular steel strip (200) passes through the welding area at a constant speed, thereby forming a weld seam (500); S3.

3. Monitor the output power of the high-frequency power supply and the pressure of the squeezing roller (300) in real time, and adjust the welding parameters, including the output power, welding speed, pressure of the squeezing roller (300), and the degree of the opening angle (201), in combination with the defect suppression model to predict and reduce the generation of welding defects; S3.

4. As the tubular steel strip (200) runs at a constant speed, the molten metal in the opening angle (201) area is gathered and welded under the pressure of the squeezing roller (300), and continuous burrs are generated after welding.

7. The high-frequency induction welding repair method according to claim 6, characterized in that, In the step S3.1, the heat input value is 14 - 19 kJ / m; In the step S3.2, the welding speed of the tubular steel strip (200) is 70 - 90 m / min.

8. The high-frequency induction welding repair method according to claim 6, wherein The monitoring is realized through a feedback control algorithm. Specifically, the algorithm automatically adjusts the high-frequency power supply power, welding speed, and the pressure of the squeezing roller (300) according to the length of the molten metal area formed during the welding process.

9. The high-frequency induction welding repair method according to claim 1, wherein The step S4 includes: S4.

1. The welded steel pipe is cooled naturally by air to avoid the generation of residual stress; S4.

2. Observe the morphology of the burrs; and observe the microstructure of the metal in the weld (500) area through SEM, and then remove the burrs; S4.

3. Test the hardness, tensile strength, and corrosion resistance of the metal in the weld (500) area.

10. A high-frequency induction welding repair device with a stainless steel inner lining, which is used to implement the high-frequency induction welding repair method described in any one of claims 1 to 9, and is characterized in that, This high-frequency induction welding repair device includes: An induction coil (100) is arranged around the opening angle (201) area of the tubular steel strip (200) and is electrically connected to the high-frequency power supply to generate an alternating magnetic field through a high-frequency current, and then generate resistance heat to melt the metal in the opening angle (201) area of the tubular steel strip (200); Two squeezing rollers (300) are symmetrically arranged on both sides of the opening angle (201) of the tubular steel strip (200) to squeeze the molten metal from both sides to the middle, so that the molten metal welds the opening angle (201) and forms a weld (500); An impedance device (400) is arranged inside the tubular steel strip (200) near the opening angle (201) to guide the current generated by the magnetic field to concentrate on the opening angle (201).

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