A welding method for a thin-gauge pipeline steel plate

Abstract

The application provides a welding method of a thin-gauge pipeline steel plate, wherein the method comprises the following steps: opening an X-shaped groove in the steel plate along a rolling direction, the X-shaped groove comprising an outer welding side groove and an inner welding side groove; adopting a double-wire submerged arc welding process to weld an inner side weld of the steel plate, and adding a copper block at a position of an outer side weld of the steel plate to cool the weld and a heat-affected zone; after the inner side weld is welded, adopting the double-wire submerged arc welding process to weld the outer side weld of the steel plate, and passing cold air into the inner side weld of the steel plate to cool the weld and the heat-affected zone. The application solves the problem that the width of the heat-affected zone increases when the thin-gauge pipeline steel plate is welded, and the pipeline steel appears a hydrogen embrittlement risk in a hydrogen transmission environment, greatly reduces the width of the heat-affected zone, and makes the pipeline steel welded joint meet mechanical property requirements such as impact and tensile, so as to ensure the quality of the pipeline steel plate welded joint.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel pipe welding and submerged arc welding, and particularly relates to a welding method for a thin-gauge pipeline steel plate. BACKGROUND

[0002] At present, there are many challenges in the transportation and storage of hydrogen energy. Hydrogen-doped pipeline transportation is considered to be the most economical way for large-scale hydrogen production and long-distance hydrogen transportation, and is of great significance for reducing hydrogen transportation costs and expanding transportation range. Long-distance hydrogen-doped transportation mostly uses small-diameter, low-grade pipeline steel (X42, X52). Low-alloy high-strength steel is prone to hydrogen embrittlement in a hydrogen environment. Hydrogen causes a decrease in material plasticity, and the incorporation of hydrogen has a significant impact on the fracture and fatigue properties of pipeline steel. The incorporated hydrogen reduces the fracture toughness of the steel.

[0003] Pipeline steel is mostly made by submerged arc welding, and the welded joint is the area with the largest composition fluctuation, uneven performance distribution and the weakest performance of pipeline steel. The microstructure of the heat-affected zone, especially the coarse-grained zone, changes unevenly under the action of welding thermal cycle, the grains are coarsened, and the fracture toughness, fatigue performance and the like are further reduced, which seriously affects the service of the pipeline steel.

[0004] Therefore, how to use an effective method to reduce the influence of the width of the heat-affected zone of the thin-gauge pipeline steel plate on the quality of the welded joint of the steel plate during welding, so that the welded joint of the pipeline steel meets the mechanical performance requirements such as impact and tensile strength, is a technical problem to be solved. SUMMARY

[0005] The purpose of the present application is to provide a welding method for a thin-gauge pipeline steel plate. The present application solves the problem that the width of the heat-affected zone of the thin-gauge pipeline steel plate increases the risk of hydrogen embrittlement of the pipeline steel in a hydrogen-doped environment during welding, greatly reduces the width of the heat-affected zone, and makes the welded joint of the pipeline steel meet the mechanical performance requirements such as impact and tensile strength, thereby ensuring the quality of the welded joint of the pipeline steel plate.

[0006] Specifically, the present application adopts the following technical solutions:

[0007] According to one embodiment of the present application, a welding method for a thin-gauge pipeline steel plate is provided, which includes the following steps: an X-shaped groove is formed on the steel plate along the rolling direction, the X-shaped groove includes an outer welding side groove and an inner welding side groove; a double-wire submerged arc welding process is used to weld the inner side weld of the steel plate, and a copper block is arranged at the position of the outer side weld of the steel plate to cool the weld and the heat-affected zone; after the inner side weld is welded, a double-wire submerged arc welding process is used to weld the outer side weld of the steel plate, and cold air is introduced into the inner side weld of the steel plate to cool the weld and the heat-affected zone.

[0008] In some embodiments of the present application, based on the foregoing scheme, when the X-shaped groove is opened on the steel plate along the rolling direction, the method further comprises: determining the preset thickness according to D=[d / 2-1], wherein D is the preset thickness, d is the thickness of the steel plate, unit: mm, and [] is the integer function; reserving a land on the X-shaped groove according to the preset thickness, and the deviation between the actual thickness of the land and the preset thickness is controlled within ±0.5 mm.

[0009] In some embodiments of the present application, based on the foregoing scheme, the groove angle of the outer welding side groove is 75°-105°, and the groove angle of the inner welding side groove is 65°-95°.

[0010] In some embodiments of the present application, based on the foregoing scheme, the size of the copper block is 15 cm*10 cm*3 cm.

[0011] In some embodiments of the present application, based on the foregoing scheme, when the double-wire submerged arc welding process is used to weld the outer weld of the steel plate, the method further comprises: controlling the interlayer welding temperature to be <100°C.

[0012] In some embodiments of the present application, based on the foregoing scheme, when the cold air is introduced into the inner weld of the steel plate, the method further comprises: controlling the cold air temperature to be <10°C, and the cold air covering the weld length is ≥40 cm.

[0013] In some embodiments of the present application, based on the foregoing scheme, the welding speed when welding the inner weld of the steel plate and when welding the outer weld of the steel plate is 1.25 m / min-1.5 m / min.

[0014] In some embodiments of the present application, based on the foregoing scheme, the welding material for welding includes H08Mn2Si welding wire with a diameter of 4.0 mm and SJ101 flux, wherein the main chemical components of the H08Mn2Si welding wire are C≤0.11%, Mn 1.7-2.1%, Si 0.65-0.95%, Cr≤0.20%, Ni≤0.30%, Cu≤0.20%, S≤0.035%, P≤0.035%, and the SJ101 flux meets the GB / T F4A2-H08MnA standard.

[0015] In some embodiments of the present application, based on the foregoing scheme, the welding wire for welding includes a first welding wire and a second welding wire, and the method further comprises: the current used by the first welding wire when welding the inner weld of the steel plate is I=8.3*d+510, and the voltage used is 32 V-34 V; the current used by the second welding wire when welding the inner weld of the steel plate is I=4.2*d+405, and the voltage used is 34 V-36 V.

[0016] Wherein, d is the thickness of the steel plate.

[0017] In some embodiments of the present application, based on the foregoing scheme, the method further comprises:

[0018] The current used by the first welding wire when welding the outer side weld of the steel plate is I = 20.8 * d + 585, and the voltage used is 34V-36V; the current used by the second welding wire when welding the outer side weld of the steel plate is I = 33.3 * d + 260, and the voltage used is 36V-38V; wherein, d is the thickness of the steel plate.

[0019] From the above technical scheme, the present application has at least the following advantages and positive effects:

[0020] By adopting the scheme of the present application, on the one hand, the present application can solve the problem that the width of the heat-affected zone increases when the thin-gauge pipeline steel plate is welded, and the risk of hydrogen embrittlement of the pipeline steel in the hydrogen environment, thereby greatly reducing the width of the heat-affected zone, and making the pipeline steel welded joint meet the mechanical performance requirements such as impact and tensile, thereby ensuring the quality of the pipeline steel plate welded joint; on the other hand, the present application adopts a double-wire submerged arc welding process to weld the outer side weld of the steel plate, which reduces the width of the heat-affected zone of the submerged arc welded joint by using reasonable welding materials and optimizing welding parameters, and greatly improves the efficiency of welding. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the present application, the following will briefly introduce the drawings needed to be used in the embodiments. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0022] Figure 1 A flow chart of the welding method of the thin-gauge pipeline steel plate in one embodiment of the present application is shown;

[0023] Figure 2 A side view of the X-shaped groove opened along the rolling direction of the steel plate in one embodiment of the present application is shown;

[0024] Figure 3 A schematic diagram of the outer welding side groove and the inner welding side groove of the X-shaped groove in one embodiment of the present application is shown;

[0025] Figure 4 A schematic diagram of the width of the heat-affected zone on both sides of the steel plate after welding in one embodiment of the present application is shown;

[0026] Figure 5A microstructure diagram of a heat-affected zone after welding by the welding method of the present application in one embodiment of the present application is shown. DETAILED DESCRIPTION

[0027] Example implementations will now be described more fully with reference to the accompanying drawings. Example implementations may, however, be implemented in many different forms and should not be construed as limited to the examples set forth herein; rather, these implementations are provided so that this disclosure will be thorough and complete, and will fully convey the scope of example implementations to those skilled in the art.

[0028] Moreover, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments of the application. One skilled in the relevant art will recognize, however, that the

[0029] The flow charts shown in the drawings are merely illustrative examples and do not necessarily include all content and operations / steps, nor are they necessarily executed in the order described. For example, some operations / steps can be further broken down, and some operations / steps can be combined or partially combined, so the actual execution order can be changed according to actual conditions.

[0030] It should be noted that the terms "first", "second", and the like in the description and in the claims of the present application and the above drawings are used to distinguish similar objects and are not necessarily used to describe a particular sequential or chronological order. It should be understood that the objects so designated can be interchanged, where appropriate, to facilitate the herein description of the embodiments of the present application.

[0031] The implementation details of the technical solutions of the embodiments of the present application are described in detail as follows:

[0032] Reference Figure 1 , Figure 1 A flow chart of a welding method for a thin-gauge pipeline steel plate in one embodiment of the present application.

[0033] In the present application, a welding method for a thin-gauge pipeline steel plate is proposed, which can be used to weld a pipeline steel for transporting hydrogen energy. The welded joint of the pipeline is the area with the largest composition fluctuation, uneven performance distribution, and the weakest of the pipeline steel, and the microstructure of the heat-affected zone, especially the coarse-grained zone, changes unevenly under the action of welding thermal cycle, the grain coarsens, the fracture toughness and fatigue performance decrease, and the service of the pipeline steel is seriously affected.

[0034] According to a typical embodiment of this application, a welding method for thin-gauge pipeline steel plates is provided, the method comprising the following steps S1 to S3:

[0035] Step S1: An X-shaped bevel is made in the steel plate along the rolling direction. The X-shaped bevel includes an outer welding side bevel and an inner welding side bevel.

[0036] In this application, as Figure 2 As shown, before welding the steel plate seams of the pipeline steel, an X-shaped bevel is first made on the steel plate along the rolling direction. This X-shaped bevel can be made mechanically, as shown in the reference. Figure 3 The X-shaped bevel may include an outer weld side bevel ( Figure 3 The β shown) and the inner weld side bevel ( Figure 3 As shown in α), the function of creating an X-shaped groove is to ensure that the weld root is fully penetrated, allowing the welding heat source to reach deep into the joint root, thus ensuring the quality of the weld joint. It can also improve welding productivity and save welding wire. The use of an X-shaped groove can also prevent the steel plate from deforming after welding, greatly improving the quality of the steel plate after welding.

[0037] Step S2: The inner weld of the steel plate is welded using a double-wire submerged arc welding process, and a copper block is added at the outer weld position of the steel plate to cool the weld and heat-affected zone.

[0038] In this application, the welding process used is the double-wire submerged arc welding process. Compared with single-wire welding, the production efficiency of double-wire welding can be increased by more than 100%. Moreover, double-wire welding results in a deeper weld thickness and a faster welding speed, which can reduce the weld bevel. The double-wire submerged arc welding flux has a good protective effect, and there will be no spatter or arc radiation, making the working environment of the workers more comfortable.

[0039] In this application, after the X-shaped bevel is cut into the steel plate, an angle grinder can be used to remove the oil and rust from the bevel and the area within 15mm on both sides of the bevel, and polish it to a metallic luster (other methods can also be used for polishing and removing oil or rust). If there is no oil or rust on the bevel and the area within 15mm on both sides of the bevel, polishing is not necessary. Removing the oil or rust from the bevel and the area within 15mm on both sides of the bevel before welding can improve the quality of the weld.

[0040] In the present application, after the X-shaped groove is opened on the steel plate, the double-wire submerged arc welding process can be used to weld the inner side weld of the steel plate. When the inner side weld of the steel plate is welded, a copper block can be arranged at the position of the outer side weld. Since the temperature of the weld and the surrounding area of the weld will rapidly increase when the outer side weld is welded again, when the temperature of the surrounding area of the weld is too high, the base metal at both ends of the weld will change obviously in structure and performance, and after cooling, the microcrystalline grains of the steel material will be coarse, and the mechanical properties, plasticity and toughness will obviously decrease (the area where the base metal on both sides of the weld changes obviously in structure and performance is called the heat-affected zone, and the width of the heat-affected zone will also affect the quality of the welded joint. The width of the heat-affected zone can indirectly judge the welding quality. The narrower the heat-affected zone, the greater the internal stress in the welded joint, and the more prone to cracks. The wider the heat-affected zone, the more detrimental to the mechanical properties of the joint, and the greater the welding deformation. Therefore, the process should ensure that the width of the heat-affected zone is as small as possible without causing cracks, so as to ensure the quality of the welded joint of the steel plate.

[0041] Step S3, after the inner side weld is welded, the outer side weld of the steel plate is welded by using the double-wire submerged arc welding process, and cold air is introduced into the inner side weld of the steel plate to cool the weld and the heat-affected zone.

[0042] In the present application, after the inner side weld of the steel plate is welded, the outer side weld of the steel plate is welded by using the double-wire submerged arc welding process, and cold air is introduced into the inner side weld of the steel plate to cool the weld and the heat-affected zone, thereby reducing the width of the heat-affected zone and ensuring the quality of the welded joint of the steel plate.

[0043] In an embodiment of the present application, when the X-shaped groove is opened on the steel plate in the rolling direction, the method further comprises:

[0044] The preset thickness is determined according to D=[d / 2-1], wherein D is the preset thickness, d is the thickness of the steel plate, unit: mm, and [] is the integer function.

[0045] According to the preset thickness, a land is reserved at the X-shaped groove, and the deviation between the actual thickness of the land and the preset thickness is controlled within ±0.5 mm.

[0046] In the present application, with reference to Figure 2 or Figure 3In the process of opening the X-shaped groove, a preset thickness of the land needs to be reserved, the preset thickness of the land can prevent the burn-through accident during the welding, and the preset thickness can be determined according to D=[d / 2-1], wherein D is the preset thickness, d is the thickness of the steel plate, unit: mm, and [] is the integer function; when the thickness d of the steel plate is 10.8 mm, the preset thickness D=[d / 2-1]=4 mm; it should be noted that the deviation between the actual thickness of the land and the preset thickness is controlled within ±0.5 mm, so when the thickness d of the steel plate is 10.8 mm, the preset thickness D can be 3.5 mm-4.5 mm.

[0047] In an embodiment of the present application, the groove angle of the outer welding side groove is 75°-105°, and the groove angle of the inner welding side groove is 65°-95°.

[0048] In the present application, with reference to Figure 3 , the groove angle of the outer welding side groove can be 75°-105°, and the groove angle of the inner welding side groove can be 65°-95°; the groove angle is used to make the electric arc penetrate into the root of the weld, so that the land is penetrated, and slag is easily removed, so that an aesthetic weld is obtained, and the quality of the steel plate welding joint can also be improved.

[0049] In an embodiment of the present application, the size of the copper block can be 15 cm*10 cm*3 cm.

[0050] In the present application, when the inner side weld of the steel plate and the outer side weld of the steel plate are welded, the welding equipment can remain stationary, and the steel plate is moved to complete the weld welding; when the inner side weld is welded, a copper block is arranged at the position of the outer side weld of the steel plate, the size of the copper block can be 15 cm*10 cm*3 cm, or other sizes, the present application does not make special limitation on this, the size can be selected according to the actual demand, the position of the copper block is fixed and does not move with the steel plate, the copper block is always the same as the position of the welding pool (when welding, the temperature of the welding pool is higher than that of other places, the copper block can absorb heat and play a role in reducing temperature, avoiding the burn-through phenomenon, and also reducing the width of the heat affected zone).

[0051] In an embodiment of the present application, when the double-wire submerged arc welding process is used to weld the outer side weld of the steel plate, the method further comprises: controlling the interlayer welding temperature to be less than 100℃.

[0052] In the application, when the double-wire submerged arc welding process is used to weld the outer weld of the steel plate, the inner weld of the steel plate needs to be welded and the temperature of the inner weld and the heat affected zone of the steel plate needs to be less than 100℃ before the outer weld of the steel plate is welded, so as to avoid the temperature of the welded part being too high when the outer weld of the steel plate is welded, and accidents such as burning through occur, thereby affecting the quality of the welded joint of the steel plate.

[0053] In an embodiment of the application, when cold air is introduced into the inner weld of the steel plate, the method further comprises: the temperature of the cold air can be controlled to be less than 10℃, and the cold air covers a weld length of greater than or equal to 40cm.

[0054] In the application, when the outer weld is welded, cold air can be introduced into the inner weld, which can cool the welded inner weld. The temperature of the cold air can be controlled to be less than 10℃, and the cold air covers a weld length of greater than or equal to 40cm, so as to reduce the width of the heat affected zone and ensure the quality of the welded joint of the steel plate.

[0055] In an embodiment of the application, the welding speed when welding the inner weld of the steel plate and the welding speed when welding the outer weld of the steel plate are 1.25m / min to 1.5m / min.

[0056] In the application, by using the scheme provided in the application, the welding speed when welding the inner weld of the steel plate and the welding speed when welding the outer weld of the steel plate can reach 1.25m / min to 1.5m / min, which greatly improves the welding efficiency.

[0057] In an embodiment of the application, the welding material for welding can include H08Mn2Si welding wire with a diameter of 4.0mm and SJ101 flux, wherein the main chemical components of the H08Mn2Si welding wire are C≤0.11%, Mn 1.7-2.1%, Si 0.65-0.95%, Cr≤0.20%, Ni≤0.30%, Cu≤0.20%, S≤0.035%, P≤0.035%, and the SJ101 flux meets the GB / T F4A2-H08MnA standard.

[0058] In an embodiment of the application, the welding wire for welding includes a first welding wire and a second welding wire, and the method further comprises: the current used by the first welding wire when welding the inner weld of the steel plate is I=8.3*d+510, and the voltage used is 32V-34V; the current used by the second welding wire when welding the inner weld of the steel plate is I=4.2*d+405, and the voltage used is 34V-36V; wherein d is the thickness of the steel plate.

[0059] In an embodiment of the application, the method further comprises:

[0060] The current used by the first welding wire when welding the outside weld of the steel plate is I = 20.8 * d + 585, and the voltage used is 34V-36V; the current used by the second welding wire when welding the outside weld of the steel plate is I = 33.3 * d + 260, and the voltage used is 36V-38V; wherein d is the thickness of the steel plate.

[0061] In the present application, a double-wire submerged arc welding process is used for welding, and the welding wire used for welding can include a first welding wire and a second welding wire, and the first welding wire and the second welding wire are used for welding at the same time, and the current and voltage used by the first welding wire and the second welding wire are different when welding the inside weld of the steel plate and the outside weld of the steel plate, and the voltage used by the first welding wire and the second welding wire is determined according to the thickness of the steel plate, thereby ensuring the quality of the steel plate welding joint.

[0062] In the present application, the current used by the first welding wire when welding the outside weld of the steel plate is I = 20.8 * d + 585, and the voltage used is 34V-36V; the current used by the second welding wire when welding the outside weld of the steel plate is I = 33.3 * d + 260, and the voltage used is 36V-38V; wherein d is the thickness of the steel plate.

[0063] It should be noted here that when welding the outside weld of the steel plate, the voltage used by the first welding wire is 2V (volts) higher than the voltage used by the second welding wire, for example, when welding the outside weld of the steel plate, the voltage used by the first welding wire is 34V, and the voltage used by the second welding wire is 36V.

[0064] In the present application, the current used by the first welding wire when welding the inside weld of the steel plate is I = 8.3 * d + 510, and the voltage used is 32V-34V; the current used by the second welding wire when welding the inside weld of the steel plate is I = 4.2 * d + 405, and the voltage used is 34V-36V; wherein d is the thickness of the steel plate.

[0065] It should be noted here that when welding the inside weld of the steel plate, the voltage used by the first welding wire is 2V (volts) higher than the voltage used by the second welding wire, for example, when welding the inside weld of the steel plate, the voltage used by the first welding wire is 33V, and the voltage used by the second welding wire is 35V.

[0066] The specific embodiments of the present application will be further illustrated by specific examples below, but the specific embodiments of the present application are not limited to the following examples.

[0067] In one embodiment of the present application, L360 grade pipeline steel is selected, the thickness is 10.8 mm, and the component composition mass percentage is: C 0.04%~0.06%; Si 0.1%~0.3%; Mn 0.5%~0.8%; P≤0.006%; S≤0.006%; Nb 0.02%~0.04%; Ti 0.01%~0.02%; V 0.02%~0.04%; Ni 0.1%~0.3%; Cu≤0.1%~0.2%; Cr≤0.1%~0.3%; carbon equivalent Ceq 0.23; cold cracking coefficient Pcm≤0.11.

[0068] The specific implementation method is shown in the following steps S11 to S33:

[0069] In step S11, the bevel of the pipeline steel plate is processed by a mechanical method, an X-shaped bevel is formed along the rolling direction of the steel plate, the bevel angle of the outer welding side bevel is 90°, the bevel angle of the inner welding side bevel is 80°, and the root face is 4 mm.

[0070] In step S22, the welding is cleaned before welding, the oil stains and rust layers within 15 mm of the bevel and both sides of the bevel are removed by an angle grinder, and the metal gloss is polished.

[0071] In step S33, the submerged arc connection pipe is welded, and the welding material selects H08Mn2Si welding wire with a diameter of 4.0 mm matched with SJ101 flux.

[0072] First, the inner side weld of the steel plate is welded, a copper block is arranged at the position of the outer side weld before welding to cool the weld and the heat affected zone, the length, width and thickness of the copper block are 15 cm*10 cm*3 cm, the copper plate is fixed and does not move with the steel plate. After the inner side welding is completed, the temperature of the steel plate welding position is measured, the interlayer temperature is controlled to be less than 100℃ (after the inner side welding of the steel plate is completed, the temperature of the inner side weld and the surrounding weld is less than 100℃), and then the outer side weld is welded. During the welding process, cold air with a temperature of less than 10℃ is used to cool the weld and the heat affected zone. The specific welding parameters are shown in Table 1.

[0073] Table 1 is the welding parameter of double-wire submerged arc welding.

[0074]

[0075] In the present application, it should be noted that, in order to verify that the scheme proposed in the present application has a large beneficial effect, after the inner and outer welding is completed, a metallographic sample is taken from the welded joint, the size of the sample is 30 mm*15 mm*10.8 mm, the sample can be polished by using 200 mesh and 800 mesh sandpaper, then polished on a polishing machine, and a 4% nitric acid alcohol is used to erode the metallographic phase, and the macroscopic morphology of the welded joint is photographed on a stereoscope, such as Figure 4Test the heat-affected width at 10 locations (upper and lower surfaces of the weld, one-quarter thickness from the upper and lower surfaces, and the core). Figure 4 The distance from the fusion line to the edge of the heat-affected zone (dashed line) was calculated as the average value. The average width of the heat-affected zone using conventional welding methods (where welding parameters are not precisely controlled and no cooling measures are taken) is 2.5 mm. The average width of the heat-affected zone obtained by the welding method of this invention is 0.8 mm, representing a 68% reduction in width. Observing the microstructure of the heat-affected zone under an optical microscope, the coarse-grained zone microstructure of the conventional welding method is coarse bainite, while the bainite microstructure obtained using the submerged arc welding process of this invention is finer. Figure 5 As shown.

[0076] The tensile, bending, and impact properties of the welded joints obtained by conventional welding methods and the welding method of this invention were tested. The results are shown in Table 2 below. The tensile and bending properties both meet the technical requirements. Compared with the conventional method, the method of this invention improves the absorption of impact energy at -10℃ in the weld center and heat-affected zone by an average of 3.9% and 19.6%, respectively. The specific comparison data are shown in Table 2 below.

[0077] Table 2 compares the tensile, bending, and impact properties of welded joints obtained by conventional welding methods and the welding method of this invention.

[0078]

[0079] As can be seen from the above technical solution, this application has at least the following advantages and positive effects:

[0080] Firstly, by adopting the solution proposed in this application, this application can solve the problem that the increased width of the heat-affected zone during welding of thin-gauge pipeline steel plates increases the risk of hydrogen embrittlement in the hydrogen transportation environment. It can significantly reduce the width of the heat-affected zone, enabling the welded joints of pipeline steel to meet the mechanical property requirements such as impact and tensile strength, thereby ensuring the quality of the welded joints of pipeline steel plates.

[0081] Secondly, the proposed solution employs a double-wire submerged arc welding process to weld the outer weld seam of the steel plate. By using appropriate welding materials and optimizing welding parameters, the width of the heat-affected zone of the submerged arc weld joint is reduced, which has a significant impact on improving the performance of pipeline steel welded joints and greatly improves welding efficiency.

[0082] Third, by adopting the scheme proposed in this application, the average width of the weld heat-affected zone is reduced by more than 50%, and the grains in the coarse-grained zone of the weld are refined, thereby improving the low-temperature impact performance of the weld heat-affected zone. This can greatly reduce the amount of pipeline steel scrap and equipment damage during welding, and significantly save resources and equipment maintenance funds.

[0083] While the application has been described with reference to several exemplary embodiments, it will be understood that the terms used are intended to be illustrative and not limiting. It will be appreciated that variations and modifications of the application can be effected without departing from the spirit or scope of the application. It will be appreciated that the above described embodiments are only illustrative of the application and not limiting. It will be understood that the above description is intended to be illustrative and not limiting. It will be appreciated that the above description is intended to be illustrative and not limiting. It will be understood that the above description is intended to be illustrative and not limiting. It will be understood that the above description is intended to be illustrative and not limiting. It will be understood that the above description is intended to be illustrative and not limiting. It will be understood that the above description is intended to be illustrative and not limiting. It will be understood that the above description is intended to be illustrative and not limiting. It will be understood that the above description is intended to be illustrative and not limiting. It will be understood that the above description is intended to be illustrative and not limiting. It will be understood that the

Claims

1. A welding method for thin-gauge pipeline steel plates, characterized in that, The method includes: An X-shaped bevel is formed in the steel plate along the rolling direction, the X-shaped bevel including an outer welding side bevel and an inner welding side bevel; The inner weld of the steel plate is welded using a double-wire submerged arc welding process, and a copper block is added at the outer weld position of the steel plate to cool the weld and heat-affected zone. After the inner weld is completed, the outer weld of the steel plate is welded using a double-wire submerged arc welding process, and cold air is introduced into the inner weld of the steel plate to cool the weld and the heat-affected zone. When opening an X-shaped bevel along the rolling direction of the steel plate, the preset thickness is determined according to D=[d / 2-1], where D is the preset thickness, d is the thickness of the steel plate in mm, and [] is a rounding function; according to the preset thickness, a blunt edge is reserved in the X-shaped bevel, and the deviation between the actual thickness of the blunt edge and the preset thickness is controlled within ±0.5mm; When using the aforementioned dual-wire submerged arc welding process, the welding wires used for welding include a first welding wire and a second welding wire; welding is performed simultaneously using the first welding wire and the second welding wire, with the voltage used for the first welding wire being 2V lower than that used for the second welding wire; the current and voltage used by the first welding wire and the second welding wire when welding the inner weld of the steel plate are different from the current and voltage used when welding the outer weld of the steel plate; The method further includes: The current used by the first welding wire when welding the inner side of the steel plate is I=8.3*d+510, and the voltage used is 32V~34V; The current used by the second welding wire when welding the inner side of the steel plate is I=4.2*d+405, and the voltage used is 34V~36V; Where d is the thickness of the steel plate; The current used by the first welding wire when welding the outer weld of the steel plate is I=20.8*d+585, and the voltage used is 34V~36V; The current used by the second welding wire when welding the outer weld of the steel plate is I=33.3*d+260, and the voltage used is 36V~38V; Where d is the thickness of the steel plate.

2. The method according to claim 1, characterized in that, The bevel angle of the outer welding side bevel is 75°~105°, and the bevel angle of the inner welding side bevel is 65°~95°.

3. The method according to claim 1, characterized in that, The copper block measures 15cm x 10cm x 3cm.

4. The method according to claim 1, characterized in that, When welding the outer weld seam of a steel plate using a double-wire submerged arc welding process, the method further includes: Control the interpass temperature during welding to be <100℃.

5. The method according to claim 1, characterized in that, When cold air is introduced into the weld seam on the inner side of the steel plate, the method further includes: Control the temperature of the cold air to be less than 10℃, and ensure that the length of the weld covered by the cold air is greater than or equal to 40cm.

6. The method according to claim 1, characterized in that, The welding speed for welding the inner weld seam and the outer weld seam of the steel plate is 1.25 m / min to 1.5 m / min.

7. The method according to claim 1, characterized in that, The welding materials used for welding include H08Mn2Si welding wire with a diameter of 4.0 mm and SJ101 flux. The main chemical composition of the H08Mn2Si welding wire is C≤0.11%, Mn1.7~2.1%, Si0.65~0.95%, Cr≤0.20%, Ni≤0.30%, Cu≤0.20%, S≤0.035%, and P≤0.035%. The SJ101 flux conforms to the GB / T F4A2-H08MnA standard.

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