A high-efficiency submerged arc welding method

Abstract

The application discloses a high-efficiency submerged-arc welding method, which comprises the following steps: butting welding plates to form a welding seam, wherein an outer side groove and an inner side groove are arranged on the welding seam, the outer side groove and the inner side groove are designed asymmetrically, the outer side groove is in a U shape, the inner side groove is in a V shape, the groove angle of the inner side groove is 70 DEG, the depth of the inner side groove is 8mm, and the root face is 2mm; bottoming the inner side groove; welding the outer side groove, wherein one single-wire submerged-arc welding, two double-wire submerged-arc weldings are adopted from inside to outside in the outer side groove, and three-wire submerged-arc welding is adopted for the remaining part; and welding the remaining part of the inner side groove. In the method, the X-shaped groove is changed into a U-shaped and V-shaped groove, the welding seam filling amount of steel plates with equal thickness is effectively reduced, and the problem of welding seam root defect rework of the X-shaped symmetric groove is avoided. In addition, the method has the advantages of good deslagging performance, beautiful welding seam forming, guaranteed welding quality of the welding seam root, and convenient automatic welding operation.

Description

Technical Field

[0001] This invention relates to the field of welding technology, specifically to a high-efficiency submerged arc welding method. Background Technology

[0002] Offshore wind power is a key area for renewable energy development. As wind turbine towers and foundations gradually move from nearshore to deep-sea areas, this places higher demands on welding technology. Traditional welding methods often suffer from low welding efficiency and difficulty in guaranteeing weld quality when dealing with thick-walled, large-sized offshore wind turbine towers and foundations.

[0003] Taking wind turbine towers as an example, the tower material has a yield strength of 355 MPa. All tower welds require full penetration, resulting in a large welding workload, post-weld ultrasonic testing, and a low weld tolerance. Furthermore, the current common practice for graded towers is to use X-groove single-wire submerged arc welding for plates thinner than 25mm, and X-groove double-wire longitudinal submerged arc welding for plates thicker than 25mm. The following problems exist when using these welding methods: 1) Taking a 50mm thick plate as an example, using an X-groove with both inner and outer bevel angles of 70°, the theoretically calculated cross-sectional area of ​​the weld is 806mm². When the plate thickness increases to 100mm, the X-groove angle remains unchanged at 70° on both the inner and outer sides, and the theoretically calculated cross-sectional area of ​​the weld increases to 3362mm². This shows that although the plate thickness only doubles, the weld metal filler volume triples. With the increasing demand for pipe piles, the number of pipe piles with plate thicknesses in the 60-120mm range is gradually increasing. The traditional X-groove combined with double-wire submerged arc welding process can no longer meet the requirements for high-efficiency welding, resulting in problems such as long welding time and waste of welding materials and energy.

[0004] 2) The X-shaped weld bevel design presents a sharp angle problem at the root weld bead, making slag removal during submerged arc welding (SAW) root pass difficult and often requiring the use of an air chisel for slag removal. Furthermore, the X-shaped bevel design results in poor accessibility of the cladding metal at the weld root, leading to frequent root welding defects. During repairs, these defects are concentrated at the weld root due to the bevel design, resulting in greater depth and further complicating the repair process.

[0005] 3) Currently, the filling amount of the X-shaped weld groove is relatively large. In order to reduce welding stress, the weld groove is generally processed symmetrically. When the plate thickness exceeds 80mm, the welding deformation increases significantly. Usually, it is necessary to repeatedly adjust the welding sequence and perform back-and-forth welding during the welding process.

[0006] 4) Thick plates often suffer from chemical composition segregation in the intermediate layer. Current symmetrical bevel designs for thick plates place the intermediate layer at the weld root, causing it to be repeatedly heated, which easily leads to hot cracking.

[0007] 5) It leads to a greater workload and generates additional working hours.

[0008] To address these issues, this invention proposes an efficient submerged arc welding method, aiming to improve welding efficiency and weld quality, and meet the welding technology requirements of offshore wind power equipment. Summary of the Invention

[0009] The purpose of this invention is to provide an efficient submerged arc welding method to solve one or more of the problems mentioned in the background art.

[0010] To achieve the above objectives, this invention discloses a high-efficiency submerged arc welding method, comprising the following steps: The butt-welded plates form a weld, which has an outer bevel and an inner bevel. The outer bevel and the inner bevel adopt an asymmetrical design, wherein the outer bevel is U-shaped and the inner bevel is V-shaped. The bevel angle of the inner bevel is 70° and the depth of the inner bevel is 8 mm; the blunt edge is 2 mm. Inner bevel base; Welding is performed on the outer bevel. From the inside to the outside of the outer bevel, one single-wire submerged arc weld and two double-wire submerged arc welds are used. The remaining part is welded with three-wire submerged arc welds. Weld the remaining portion of the inner bevel.

[0011] In some embodiments, the bevel angle of the outer bevel is 16°.

[0012] In some implementations, gas-shielded welding is used for the inner bevel root pass. The welding material used is Atlantic solid welding wire CHW-50C6SM, with a wire diameter of φ1.2mm; Welding current 280-300A, welding voltage 30-32V, welding speed 280-320mm / min; Protective gas: 100% carbon dioxide.

[0013] In some embodiments, a three-wire submerged arc welding machine is used for welding the outer bevel. The three-wire submerged arc welding machine is controlled by three independent power supplies and is equipped with three longitudinally arranged welding torches, which are used to weld the front wire, middle wire and rear wire respectively.

[0014] In some embodiments, the welding torch used for front wire welding among the three longitudinally arranged welding torches can be tilted forward by 5°±2°, and the welding torch used for back wire welding can be tilted backward by 30°±2°.

[0015] In some embodiments, when the welding wire extension length is 20mm, a gap of 5±0.5mm is left between the welding torch and both sides of the weld, so that the welding wire reaches the root of the weld.

[0016] In some implementations... The front wire is selected from welding wire containing manganese, and the middle and rear wires are selected from welding wire containing nickel. The manganese content in the middle and rear wires is less than that in the front wire. The diameter of the front and back filaments is φ4.0, and the diameter of the middle filament is φ5.0.

[0017] In some implementations... The first pass of the outer bevel is welded using a single wire, with a welding current of 650A, a welding voltage of 30V, and a welding speed of 400mm / min. The second and third passes of the outer bevel are welded using a double-wire welding method with a DC welding gun current of 700A and a voltage of 31V, an AC welding gun current of 650A and a voltage of 35V, and a welding speed of 810mm / min. The remaining outer welds are welded using a three-wire welding method. All three-wire welding is done in separate passes, with the width of a single weld not exceeding 25mm and the welding speed of each pass exceeding 1000mm / min.

[0018] In some embodiments, the outer remaining weld seam includes a filler layer and a capping layer, when performing three-wire welding. The parameters for welding the filler layer are as follows: the current of the middle wire is 90-95% of the current of the front wire, and the current of the rear wire is 80-85% of the current of the middle wire; the voltage of the rear wire is 2-4V higher than that of the front wire. The parameters for welding the cover layer are as follows: the current of the middle wire is 90-95% of the current of the front wire, and the current of the rear wire is 85-90% of the current of the middle wire; the voltage of the rear wire is 2-4V higher than that of the front wire.

[0019] In some implementations, single-wire submerged arc welding is used to weld the remaining portion of the inner bevel, forming a two-layer structure. The welding parameters for these two layers are as follows: First layer: Welding current 750A, welding voltage 31V, welding speed 360mm / min; Second layer: Welding current 680A, welding voltage 34V, welding speed 410mm / min.

[0020] Compared with the prior art, the beneficial effects of the present invention are: This method enables more efficient welding of steel plates with a thickness of 60 mm to 120 mm, and can also be used for welding longitudinal and circumferential seams. Save energy and reduce the amount of welding materials used; Solve the problem of difficult slag removal at the root of the weld and reduce welding defects at the root of the weld; Reduce workload and improve work efficiency; Reduce welding stress and improve the impact toughness of the weld root under high-speed, high-heat-input welding methods. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the weld joint bevel structure in some embodiments of the present invention; Figure 2 This is a cross-sectional view of the GMAW root pass weld in some embodiments of the present invention; Figure 3 This is a cross-sectional view of the outer root SAW monofilament underlayment in some embodiments of the present invention; Figure 4 This is a cross-sectional view of the double-wire filling at the outer root in some embodiments of the present invention; Figure 5 This is a cross-sectional view of the outer three-wire filling and cover surface in some embodiments of the present invention; Figure 6 This is a diagram showing the arrangement of welding torches in some embodiments of the present invention; Figure 7 This is a schematic diagram of the welding torch head structure in some embodiments of the present invention; Figure 8 This is a schematic diagram of the welding torch application structure in some embodiments of the present invention; Figure 9 This is a cross-sectional view of the inner monofilament filling in some embodiments of the present invention. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] This embodiment uses a 100mm thick plate as an example. (See attached image.) Figures 1 to 9 The invention discloses a high-efficiency submerged arc welding method, comprising the following steps: Step 1. Butt the steel plates to form a weld, such as... Figure 1As shown, the weld has an outer bevel and an inner bevel, which are asymmetrically designed. The outer bevel can be U-shaped with a bevel angle of 16°; the inner bevel can be V-shaped with a bevel angle of 70° and a depth of 8 mm; the blunt edge is 2 mm. The theoretically calculated cross-sectional area of ​​the weld is approximately 2406 m², about 70% of the weld metal filling volume of an X-type bevel for the same plate thickness. By changing from an X-shape to a U-shape + V-shape bevel, the weld metal filling volume for the same thickness steel plate is reduced by about 33%. This avoids the problem of repairing root defects in X-type symmetrical bevel welds. For example, with a 100 mm weld, to achieve root repair with an X-type bevel, 50 mm of weld metal needs to be removed to reach the root defect. With this bevel, only 8-10 mm of weld metal needs to be removed from the inside to remove the root defect.

[0024] Step 2. Apply the inner bevel base coat. GMAW can be used for this step. Figure 2 As shown, the specific parameters for using GMAW as a base coat are as follows: The welding material can be Atlantic solid welding wire CHW-50C6SM, with a wire diameter of φ1.2mm; Welding current 280-300A, welding voltage 30-32V, welding speed 280-320mm / min; Protective gas: 100% carbon dioxide.

[0025] Step 3. Weld the outer bevel. Submerged arc welding can be used at this stage. A Kaiyuan ACDC-1000G three-wire submerged arc welding machine can be used for this welding process. It employs three independent power supply controls (DC + AC + AC), with three welding torches arranged longitudinally (the specific arrangement of the welding torches can be seen as follows). Figure 6 As shown, by adjustment, the three welding torches can cooperate at specific angles to ensure uniform heating of the weld and a stable molten pool, thereby improving welding quality and efficiency. Specifically, the welding torch used for front-wire welding can tilt forward 5°±2° to increase the penetration depth during welding, while the welding torch used for rear-wire welding can tilt backward 30°±2° to obtain a smooth weld surface. (The torch head structure can be as follows...) Figure 7 (as shown in the structure) Figure 8As shown, when the welding wire extends 20mm beyond the welding torch, a 5mm gap can be left between the welding torch and both sides of the weld, allowing the welding wire to reach the root of the weld for welding. In this process, the front wire can be EH14 (1.70-2.20% Mn) welding wire with a high Mn content. The high manganese content helps deoxidize and desulfurize, reducing hot cracking and compensating for weld strength. Specifically, Atlantic welding wire CHW-EH14 (Mn: 1.70-2.20%, Si: ≤0.10%) with a diameter of φ4.0 can be used. The middle and rear wires can be welding wires with low manganese content but added Ni (1.50-1.90% Mn, 0.16-0.30% Ni). Due to the loss of alloying elements, weld strength and toughness decrease. Adding appropriate Ni to the middle wire ensures that the weld meets the low-temperature impact requirements at -40℃. Specifically, Atlantic CHW-S3A can be used for the middle wire with a diameter of φ5.0 (1.50-1.90%). Mn, 0.16-0.30%Ni); the rear wire uses Atlantic CHW-S3A with a diameter of φ4.0. The flux used can be Atlantic CHF-135 (CaF2≥20%). The front wire uses φ4.0 wire, which, with its small diameter, allows for higher current density and greater penetration at the same welding current. The middle wire uses φ5.0 wire, creating a three-wire fusion pool. The middle wire utilizes the heat from the front and rear wires, allowing for the use of a larger diameter wire without increasing the current, thus improving cladding efficiency. The welding parameters for the rear wire are mainly for weld surface formation. The front wire balances weld penetration and melting efficiency, while the middle wire cleverly utilizes the heat from the front and rear wire fusion pools, increasing the wire diameter and improving cladding efficiency without increasing weld heat input. For the high heat input three-wire submerged arc welding method, wires with different chemical elements are selected for the front, middle, and rear wires to ensure a weld center impact value of ≥70J at -40℃.

[0026] During this welding process: For the first pass of the outer bevel, only the welding torch with the front wire of a three-wire submerged arc welding machine can be used, i.e., DC power supply single-wire welding, with a welding current of 650A, welding voltage of 30V, and welding speed of 400mm / min. Figure 3 The diagram shows the weld arrangement. The parameters of 650A current ensure the weld penetration depth and 30V voltage ensure the appropriate weld width. The slag removal of the first weld was particularly smooth. For the second and third passes of the outer bevel, a welding torch on a three-wire submerged arc welding machine with both the front and middle wires can be used, i.e., AC / DC dual-power dual-wire welding. The front wire is powered by a DC welding torch with a current of 700A and a voltage of 31V, while the middle wire is powered by an AC welding torch with a current of 650A and a voltage of 35V, and the welding speed is 810mm / min. Figure 4 This is a schematic diagram of the weld arrangement. The two-layer weld uses a double-wire welding method, eliminating the need for separate passes, resulting in good weld formation and slag removal. The remaining outer welds are welded using three-wire welding, and each three-wire weld is welded in separate passes, with the width of a single weld not exceeding 25mm. Figure 5 This is a schematic diagram of the weld distribution; the welding speed of all three wires exceeds 1000 mm / min; The fill and capping parameters for the three-wire submerged arc welding process are shown in Tables 1 and 2 below: Filler layer parameters: (The current of the middle wire is 90-95% of the current of the front wire, and the current of the back wire is 80-85% of the current of the middle wire; the voltage of the back wire is 2-4V higher than that of the front wire).

[0027] Table 1 Cover layer parameters: (The current of the middle wire is 90-95% of the current of the front wire, and the current of the back wire is 85-90% of the current of the middle wire; the voltage of the back wire is 2-4V higher than that of the front wire).

[0028] Table 2 Step 3. Weld the remaining part of the inner bevel. Figure 9 The diagram shows the weld distribution. This welding process can be performed using a single-wire submerged arc welding torch on a three-wire submerged arc welding machine with only the front wire used for welding. The first layer has a welding current of 750A, a welding voltage of 31V, and a welding speed of 360mm / min. The second layer has a welding current of 680A, a welding voltage of 34V, and a welding speed of 410mm / min. The outer weld root bead uses one layer of single-wire submerged arc welding and two layers of double-wire submerged arc welding, with fixed welding parameters selected to ensure good slag removal and aesthetically pleasing weld formation. Similarly, the inner 70° bevel angle and 8mm depth also use fixed welding parameters. These fixed parameters prevent human error and ensure the welding quality at the weld root. The Kaiyuan ACDC-1000G three-wire submerged arc welding machine has a welding parameter retrieval function, allowing for direct retrieval of welding program parameters.

[0029] All of the above-mentioned undisclosed matters can be implemented using existing technologies, so they will not be elaborated here.

[0030] Finally, it should be noted that in the description of this invention, the terms "vertical," "upper," "lower," "horizontal," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0031] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set", "install", "connect", and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0032] The above description, in conjunction with specific embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all such deductions or substitutions should be considered to fall within the scope of protection defined by the claims submitted herein.

Claims

1. A high-efficiency submerged arc welding method, characterized in that, Includes the following steps: The butt-welded plates form a weld, which has an outer bevel and an inner bevel. The outer and inner bevels are asymmetrically designed. The outer bevel is U-shaped with a bevel angle of 16°. The inner bevel is V-shaped with a bevel angle of 70° and a depth of 8 mm. The blunt edge is 2 mm. Inner bevel base; Welding is performed on the outer bevel. From the inside to the outside of the outer bevel, one single-wire submerged arc welding and two double-wire submerged arc welding are used. The remaining part is welded using a three-wire submerged arc welding machine. The three-wire submerged arc welding machine is controlled by three independent power supplies. The three-wire submerged arc welding machine is equipped with three longitudinally arranged welding torches. The three welding torches are used to weld the front wire, the middle wire, and the rear wire, respectively. The diameter of the front wire and the rear wire is φ4.0, and the diameter of the middle wire is φ5.

0. Weld the remaining portion of the inner bevel; The first pass of the outer bevel is welded using a single wire, with a welding current of 650A, a welding voltage of 30V, and a welding speed of 400mm / min. The second and third passes of the outer bevel are welded using a double-wire welding method with a DC welding gun current of 700A and a voltage of 31V, an AC welding gun current of 650A and a voltage of 35V, and a welding speed of 810mm / min. The remaining outer weld seam is welded using a three-wire welding method, with each three-wire weld being multi-pass welding. The width of a single weld pass does not exceed 25mm, and the welding speed for each three-wire weld exceeds 1000mm / min. The remaining outer weld seam includes a filler layer and a capping layer. When performing three-wire welding... The parameters for welding the filler layer are as follows: the current of the middle wire is 90-95% of the current of the front wire, and the current of the rear wire is 80-85% of the current of the middle wire; the voltage of the rear wire is 2-4V higher than that of the front wire. The parameters for welding the cover layer are as follows: the current of the middle wire is 90-95% of the current of the front wire, and the current of the rear wire is 85-90% of the current of the middle wire; the voltage of the rear wire is 2-4V higher than that of the front wire.

2. The high-efficiency submerged arc welding method according to claim 1, characterized in that, When beveling the inner side, gas-shielded welding is used for the root pass. The welding material used is Atlantic solid welding wire CHW-50C6SM, with a wire diameter of φ1.2mm; Welding current 280-300A, welding voltage 30-32V, welding speed 280-320mm / min; Protective gas: 100% carbon dioxide.

3. The high-efficiency submerged arc welding method according to claim 1, characterized in that, The welding torches arranged longitudinally are tilted forward by 5°±2° for front wire welding and backward by 30°±2° for rear wire welding.

4. The high-efficiency submerged arc welding method according to claim 3, characterized in that, When the welding wire extension length is 20mm, the welding torch leaves a gap of 5±0.5mm between the welding torch and both sides of the weld, allowing the welding wire to reach the root of the weld.

5. The high-efficiency submerged arc welding method according to claim 1, characterized in that, The front wire is a welding wire containing manganese, and the middle and rear wires are welding wires containing nickel. The manganese content in the middle and rear wires is less than that in the front wire.

6. The high-efficiency submerged arc welding method according to claim 1, characterized in that, When welding the remaining part of the inner bevel, single-wire submerged arc welding is used to weld a two-layer structure. The parameters for welding these two layers are as follows: First layer: Welding current 750A, welding voltage 31V, welding speed 360mm / min; Second layer: Welding current 680A, welding voltage 34V, welding speed 410mm / min.

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