Non-columnar large-width three-wire submerged arc welding method

Abstract

The application discloses a non-longitudinal arrangement large-width-of-fusion three-wire submerged-arc welding method, which is suitable for multi-layer single-pass welding of wide-groove thick plates, and is especially suitable for steel structures with dynamic load fatigue requirements and prohibited multi-pass welding. The core of the method is to adopt differential non-longitudinal arrangement in stages. In the bottoming and filling welding stage, the first wire is arranged in the center, and the second and third wires are arranged in a left-right cross distribution mode, so that root penetration is ensured and a micro-concave weld is formed. In the surface welding stage, the first and second wires are arranged in a left-right cross distribution mode, and the third wire is arranged in the center, so that smooth transition of the weld toe is ensured. Meanwhile, a positive correlation matching relationship between the longitudinal spacing of the welding wires, heat input, lateral offset and the groove width and heat input is established, so that the heat of the molten pool is uniformly distributed in the lateral direction. The single-pass width of fusion can be increased by more than 30% by the method, and wide-groove single-pass forming can be realized without welding. The weld forming is excellent, the defect rate is low, the process adaptability is strong, and the method can be widely applied to the manufacture of thick plate structures such as bridges and pressure vessels with high fatigue requirements.

Description

Technical Field

[0001] This invention belongs to the field of submerged arc welding technology, specifically relating to a non-longitudinal arrangement of three-wire submerged arc welding with large weld width. It is suitable for multi-layer single-pass welding of thick plate wide groove structures, especially for the manufacture of large steel structure components with dynamic load fatigue requirements and prohibition of cover multi-pass welding. It can be widely used in industrial fields such as bridges, pressure vessels, energy equipment, and hoisting machinery. Background Technology

[0002] Submerged arc welding is the mainstream welding process for manufacturing large steel structures. It has advantages such as high welding efficiency, stable weld quality, good working conditions, and low overall cost in flat welding and ship-shaped welding positions. By matching different welding materials, it can meet various service performance requirements such as strength, toughness, fatigue, and corrosion resistance.

[0003] For thick steel plate structures, due to limitations in plate thickness and bevel filler volume, multi-layer multi-pass or multi-layer single-pass submerged arc welding processes are typically employed. Among these, multi-layer single-pass welding eliminates the need for transverse welding, resulting in continuous and complete weld beads, making it particularly suitable for structures with high requirements for dynamic fatigue performance. In contrast, multi-pass welding of the cap surface can create lap steps and stress concentrations between weld beads, significantly reducing the fatigue life of the joint. Therefore, many important fatigue load structures explicitly require the cap surface to be formed in a single pass.

[0004] Currently, multi-wire submerged arc welding in the industry generally adopts a longitudinal arrangement, that is, three welding wires are arranged one after the other along the welding direction and all located on the center line of the groove. This arrangement has strong penetration capability, but limited weld width. When performing multi-layer single-pass welding on wide grooves, there are three major technical challenges: First, the width of the weld pool is insufficient to cover the entire groove, and defects such as incomplete fusion, slag inclusions, and undercut are prone to occur on both sides of the groove; second, in order to ensure the filling amount, the heat input is forced to be increased, which will lead to excessive weld reinforcement and sharp weld toe transition, which will worsen fatigue performance; third, the heat of the weld pool is concentrated in the center of the groove, resulting in a large temperature gradient and poor weld formation and microstructure uniformity.

[0005] In existing publicly available technologies, most multi-wire submerged arc welding solutions are designed for single-pass welding or multi-layer, multi-pass welding of conventional X-grooves, employing traditional longitudinal wire arrangement and failing to address the issue of weld width expansion in single-pass welding of wide grooves. While some thick plate welding processes mention groove optimization, they still rely on multi-layer, multi-pass welding for filling, which cannot meet the requirements of dynamic fatigue structures for single-pass capping. In summary, existing technologies cannot achieve uniform single-pass filling and smooth capping of wide grooves without the need for multi-pass welding, necessitating the development of novel three-wire arrangement and process matching methods. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing a non-longitudinal arrangement method for large-weld-width three-wire submerged arc welding. This method breaks through the weld width limitations of traditional longitudinal arrangement, designs differentiated non-longitudinal cross arrangements to meet the different forming requirements of the root pass, fill pass, and cap pass stages, and establishes a quantitative correlation between welding wire position parameters, groove width, and welding heat input. Under the premise of a three-wire eutectic pool, it achieves a uniform lateral distribution of heat in the weld pool, significantly expands the coverage width of a single weld pass, ensures the fusion quality of the groove edge and a smooth transition of the weld toe, and ultimately achieves high-quality, multi-layer, single-pass welding with a wide groove without multi-pass welding, meeting the requirements of high dynamic fatigue structures.

[0007] To achieve the above-mentioned objectives, the technical solution of the present invention is as follows: A non-longitudinal arrangement three-wire submerged arc welding method for large weld width is proposed for multi-layer single-pass welding of thick plate wide-groove structures. In flat welding or ship-shaped welding positions, three welding wires are used to form a eutectic pool. The core lies in the phased use of differentiated non-longitudinal arrangement and the matching of longitudinal spacing, lateral offset, and process parameters in a related design. The specific details are as follows: 1. Non-longitudinal arrangement during the root pass and fill pass welding stages The core requirement for root pass welding is to ensure that the root blunt edge is fully penetrated, while forming a weld bead morphology with a slightly concave center and smooth sides, so as to avoid the central bulge causing edge inclusions in the subsequent filler weld; the filler weld, on the other hand, needs to ensure interlayer fusion and evenly cover the bevel width to provide a flat foundation for the cover pass weld.

[0008] To address the aforementioned requirements, this stage employs a non-longitudinal arrangement where the first welding wire is centered, and the second and third welding wires are positioned on either side of the bevel centerline, alternating between the two. Along the welding direction (longitudinal): Three welding wires are arranged one after the other. The first wire is the guide wire, and the second and third wires are the follow wires. A longitudinal spacing is set between adjacent welding wires to ensure the formation of a stable eutectic pool. Vertical welding direction (lateral, along the width of the bevel): The first welding wire coincides with the center line of the bevel, and the second and third welding wires are offset to the left and right sides of the center line respectively, forming a cross distribution structure.

[0009] The technical principle of this arrangement is as follows: the first guide wire in the center ensures the root penetration and interlayer fusion; the second and third follower wires distributed on both sides disperse the arc heat to both sides of the bevel, expand the width of the weld pool, ensure full fusion at the edge of the bevel, and avoid undercut and slag inclusion; at the same time, the heat of the three wires crosses and balances, naturally forming a weld bead morphology with a slightly concave center, providing a good interlayer bonding surface for subsequent filler welding and effectively reducing the risk of defects.

[0010] In the design of the welding wire tilt angle, the first guide wire is tilted forward in the welding direction to ensure penetration capability; the second and third follower wires are tilted backward in the opposite direction of welding to widen the molten pool and improve the spread; the tilt angle of the three welding wires relative to the normal of the steel plate surface is controlled within the range of 0°~15°.

[0011] 2. Non-longitudinal arrangement during the cover welding stage The core requirement for cover welding is to ensure a smooth transition between the weld toes on both sides of the bevel, while controlling the reinforcement height within a reasonable range to avoid stress concentration and meet fatigue performance requirements.

[0012] To address the aforementioned requirements, this stage employs a non-longitudinal arrangement where the first and second welding wires are positioned on either side of the bevel centerline, with the third welding wire centered in the middle. Along the welding direction (longitudinal): Three welding wires are arranged one after the other, with longitudinal spacing between adjacent welding wires; Vertical welding direction (lateral): The first and second welding wires are offset to the left and right sides of the center line respectively, directly corresponding to the welding toe areas on both sides of the bevel, and the third welding wire is located on the center line of the bevel.

[0013] The technical principle of this arrangement is as follows: the first and second welding wires arranged on both sides directly input heat to the edge of the bevel, ensuring full fusion and spread of liquid metal at the weld toe, avoiding undercut and sharp transition angles; the third welding wire in the middle supplements the filling amount of the central area, and in conjunction with the flow of liquid metal in the eutectic pool, forms a uniform and smooth micro-convex reinforcement; without performing multiple passes of welding, a wide bevel can be formed in one pass with a single-pass capping, the weld toe transition is smooth, and the fatigue performance of the joint is significantly improved.

[0014] In terms of the welding wire tilt angle design, all three welding wires are tilted backward in the opposite direction of welding to increase the width of the molten pool and improve the surface spreading quality; the tilt angle of the three welding wires relative to the normal direction of the steel plate surface is controlled within the range of 0°~15°.

[0015] 3. Correlation and matching between longitudinal spacing of welding wire and welding heat input The longitudinal spacing between adjacent welding wires is a key parameter to ensure the formation of a stable eutectic pool: if the spacing is too small, the heat will be concentrated, the molten pool will be overheated locally, and the microstructure and forming uniformity will be poor; if the spacing is too large, the eutectic pool cannot be formed, and slag inclusions and incomplete fusion defects are likely to occur.

[0016] This invention establishes a positive correlation between the longitudinal spacing and the average welding heat input of adjacent wires: the higher the heat input, the larger the molten pool size of a single welding wire, and the larger the longitudinal spacing it can withstand. The specific matching rule is as follows: When the average welding heat input of two adjacent welding wires is ≤15kJ / cm, the longitudinal spacing between adjacent welding wires is 20mm. When the average welding heat input of two adjacent welding wires is greater than 15 kJ / cm, the longitudinal spacing between the adjacent welding wires increases by 1 mm for every 2 kJ / cm increase in the average heat input.

[0017] The formula for calculating the welding heat input of a single welding wire is as follows:

[0018] In the formula, Let be the welding current (A) of the i-th welding wire. Let V be the welding voltage of the i-th welding wire. Welding speed (cm / min) The unit is kJ / cm.

[0019] 4. Correlation and matching between welding wire lateral offset and groove width and welding heat input Lateral offset is the core parameter that determines the coverage effect of the weld width: if the offset is too small, the weld width will not expand enough and defects will easily appear at the edge; if the offset is too large, it will destroy the effect of the three-wire eutectic pool and easily melt the parent material at the edge of the bevel and increase the dilution rate.

[0020] This invention establishes a positive correlation between the lateral offset and the remaining width of the bevel and the welding heat input: the wider the bevel and the higher the heat input, the greater the offset, ensuring that the edge of the molten pool always covers the sidewall of the bevel.

[0021] During the root pass and fill pass welding stages, the lateral offsets f2 and f3 of the second and third welding wires satisfy the following: When the remaining width of the bevel W ≤ 30mm, f2 and f3 are taken as 8~12mm, with the maximum value not exceeding 12mm, to ensure the stability of the eutectic pool; When the remaining groove width W > 30mm, f2 and f3 increase synchronously with the groove width and welding heat input, and the offset of the third wire is greater than that of the second wire, gradually widening the molten pool.

[0022] During the cover welding stage, the lateral offsets c1 and c2 of the first and second welding wires satisfy: When the remaining width of the bevel W ≤ 30mm, c1 and c2 are taken as 10~13mm, with the maximum value not exceeding 13mm; When the remaining bevel width W > 30mm, c1 and c2 increase synchronously with the bevel width and welding heat input to ensure full spread at the weld toe.

[0023] Furthermore, the first welding wire is connected to a DC welding power source to ensure arc stability and penetration capability; the second and third welding wires are connected to an AC welding power source to suppress magnetic blow and improve molten pool stability. The steel plate to be welded is low-alloy high-strength structural steel with an initial bevel width of 20 / 50mm; the welding wire diameter is 3.0 / 5.0mm, and it is equipped with a smelting or sintering submerged arc welding flux with performance matching the strength and toughness requirements of the base material.

[0024] Beneficial effects Compared with the prior art, the present invention has the following significant advantages: 1. Significantly expands the single-pass weld width, enabling wide-groove single-pass welding: By using a non-longitudinal cross arrangement, the arc heat is dispersed to both sides of the groove, increasing the single-pass weld coverage width by more than 30% compared to the traditional longitudinal arrangement. This allows for multi-layer single-pass welding of wide grooves without the need for multiple passes, meeting the mandatory requirements of dynamic fatigue structures for single-pass forming of the cover surface.

[0025] 2. Excellent weld formation and low defect rate: The phased and differentiated arrangement precisely matches the forming requirements of each weld bead. The undercut filler forms a central micro-concave weld bead, and the capping forms a smooth transition height. The heat is evenly distributed laterally, effectively avoiding common defects such as edge non-fusion, undercut, and slag inclusion. The weld toe transition is smooth, and the stress concentration coefficient is low.

[0026] 3. Quantitative matching of parameters and strong process adaptability: A quantitative correlation is established between longitudinal spacing, lateral offset and heat input, and bevel width. The parameters can be flexibly adjusted according to different plate thicknesses, bevel widths and steel grades. It has a wide range of applications and strong process replicability and field adaptability.

[0027] 4. High welding efficiency and low overall cost: The three-wire eutectic pool maintains the high deposition efficiency of multi-wire submerged arc welding, while eliminating the need for overlapping of multiple passes, reducing filler metal waste and welding time. The manufacturing efficiency and overall economic benefits are significantly better than traditional multi-layer and multi-pass processes. Attached Figure Description

[0028] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the non-longitudinal welding wire arrangement during the root pass and fill pass welding stages of the present invention. Figure 2 This is a schematic diagram of the non-longitudinal welding wire arrangement during the cover welding stage of the present invention.

[0029] Explanation of markings in the diagram: 1 - First welding wire; 2 - Second welding wire; 3 - Third welding wire; W - Remaining bevel width; d1 - Longitudinal spacing between the first and second welding wires; d2 - Longitudinal spacing between the second and third welding wires; f2 - Lateral offset of the second welding wire during the root pass / fill stage; f3 - Lateral offset of the third welding wire during the root pass / fill stage; c1 - Lateral offset of the first welding wire during the cover pass stage; c2 - Lateral offset of the second welding wire during the cover pass stage; The arrow direction indicates the welding direction. Detailed Implementation

[0030] The technical solution of the present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0031] This embodiment focuses on three sets of welding grooves of different widths for Q460M low-alloy high-strength structural steel thick plates, and conducts multi-layer single-pass welding tests using the non-longitudinal arrangement three-wire submerged arc welding process described in this invention. The tests use three 4.0mm diameter submerged arc welding wires, with wire type conforming to GB / T36034S55A4UFB-FUG requirements and matching flux conforming to GB / T36037SAFB1 requirements. During welding, the first welding wire is connected to a DC power supply, while the second and third welding wires are connected to an AC power supply. The welding position is a flat welding position.

[0032] Example 1: Narrow groove welding (initial groove width < 30mm) In this embodiment, the initial bevel width is less than 30mm, and the process is divided into three stages: root pass welding, fill pass welding, and cover pass welding. The specific process parameters are designed as follows: Root pass welding: The remaining width of the bevel W < 30mm, the heat input of the three wires are HI1=16kJ / cm, HI2=13kJ / cm, HI3=17kJ / cm respectively; the first wire is arranged in the center, with longitudinal spacing d1=20mm, d2=20mm; the lateral offset is f2=9mm, f3=10mm.

[0033] Filler weld: Remaining groove width W=16mm, heat input of the three wires HI1=18kJ / cm, HI2=14kJ / cm, HI3=18kJ / cm respectively; longitudinal spacing d1=20mm, d2=20mm; transverse offset f2=9mm, f3=10mm.

[0034] Cover weld: Remaining groove width W=27mm, heat input of the three wires HI1=21kJ / cm, HI2=24kJ / cm, HI3=14kJ / cm respectively; the wires on both sides and the center wire are arranged, with longitudinal spacing d1=22mm, d2=20mm; lateral offset c1=12mm, c2=12mm.

[0035] Example 2: Medium-width bevel welding (initial bevel width < 30mm, cap width approximately 32mm) In this embodiment, the initial bevel width is less than 30mm, and the bevel width increases to 32mm during the capping stage. The specific process parameters are designed as follows: Root pass welding: Remaining groove width W < 30mm, heat input of the three wires HI1 = 15kJ / cm, HI2 = 13kJ / cm, HI3 = 19kJ / cm respectively; longitudinal spacing d1 = 20mm, d2 = 20mm; transverse offset f2 = 9mm, f3 = 10mm.

[0036] Filler weld: Remaining groove width W=25mm, heat input of the three wires HI1=18kJ / cm, HI2=20kJ / cm, HI3=22kJ / cm respectively; longitudinal spacing d1=20mm, d2=23mm; transverse offset f2=9mm, f3=11.5mm.

[0037] Cover weld: Remaining bevel width W=32mm, heat input of the three wires HI1=23kJ / cm, HI2=24kJ / cm, HI3=15kJ / cm respectively; longitudinal spacing d1=22.5mm, d2=20mm; transverse offset c1=13.5mm, c2=13mm.

[0038] Example 3: Wide bevel welding (cap width 42mm) In this embodiment, the bevel width is larger, and the width of the capping stage reaches 42mm. The specific process parameters are designed as follows: For root pass welding: the remaining bevel width W < 30mm, the heat input of the three wires are HI1 = 14kJ / cm, HI2 = 16kJ / cm, and HI3 = 20kJ / cm respectively; the longitudinal spacing d1 = 20mm and d2 = 20mm; the transverse offset f2 = 9mm and f3 = 10mm.

[0039] Filler weld: Remaining groove width W=35mm, heat input of the three wires HI1=20kJ / cm, HI2=22kJ / cm, HI3=24kJ / cm respectively; longitudinal spacing d1=21.5mm, d2=24mm; transverse offset f2=12mm, f3=14.5mm.

[0040] Cover weld: Remaining bevel width W=42mm, heat input of the three wires HI1=25kJ / cm, HI2=27kJ / cm, HI3=16kJ / cm respectively; longitudinal spacing d1=23.5mm, d2=23.5mm; transverse offset c1=14mm, c2=15mm.

[0041] The core parameters of the three sets of embodiments are summarized in Table 1.

[0042] Table 1. Process parameters for non-longitudinal arrangement of three-wire submerged arc welding in the embodiment.

[0043] Welded joint quality inspection The welded joints of the three sets of embodiments were subjected to visual inspection and ultrasonic non-destructive testing, and the results are shown in Table 2.

[0044] Table 2. Quality inspection results of welded joints in the embodiments.

[0045] Test results show that the method of this invention can achieve stable multi-layer single-pass welding under different bevel widths. The weld bead completely covers the bevel width, with good edge formation and no defects such as undercut or lack of fusion. The welding quality meets the relevant standard requirements. For wider bevels, the offset and spacing can be adjusted synchronously according to the parameter matching principle of this invention to obtain stable welding results.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A non-longitudinal arrangement, wide-melt-width three-wire submerged arc welding method, for multi-layer single-pass submerged arc welding of thick plate wide-groove structural components, wherein three welding wires are used to form a eutectic pool for welding at flat welding or ship-shaped welding positions, characterized in that... Different non-column welding wire arrangements are adopted according to different welding stages, and corresponding parameter correlation designs are matched, specifically including: (1) Root pass and fill pass welding stage: The first welding wire is centered, and the second and third welding wires are arranged in a non-longitudinal arrangement on both sides of the groove center line; along the welding direction, the three welding wires are arranged in sequence with longitudinal spacing; perpendicular to the welding direction, the second and third welding wires have a lateral offset relative to the groove center line. (2) Cover welding stage: The first and second welding wires are arranged in a non-longitudinal pattern with the third welding wire in the center and the first and second welding wires on the opposite sides of the groove center line. Along the welding direction, the three welding wires are arranged in sequence with longitudinal spacing. Perpendicular to the welding direction, the first and second welding wires have a lateral offset relative to the groove center line. (3) Matching of longitudinal spacing of welding wires: The longitudinal spacing of adjacent welding wires is positively correlated with the average welding heat input of the two adjacent wires. The larger the average heat input, the larger the longitudinal spacing. (4) Matching of lateral offset of welding wire: The lateral offset of welding wires on both sides is positively correlated with the remaining width of the groove of the current weld bead and the welding heat input. The larger the groove width and the higher the heat input, the greater the lateral offset.

2. The non-longitudinal arrangement, large weld width three-wire submerged arc welding method according to claim 1, characterized in that, During the root pass and fill pass welding stages, the first welding wire is tilted forward in the welding direction, while the second and third welding wires are tilted backward in the opposite welding direction; the tilt angles of the three welding wires relative to the normal direction of the steel plate surface are all 0°~15°.

3. The non-longitudinal arrangement, large weld width three-wire submerged arc welding method according to claim 1, characterized in that, During the cover welding stage, all three welding wires are tilted backward in the opposite direction of welding; the tilt angle of the three welding wires relative to the normal direction of the steel plate surface is 0°~15°.

4. The non-longitudinal arrangement, large weld width three-wire submerged arc welding method according to claim 1, characterized in that, The matching rule for the longitudinal spacing of the welding wires is as follows: When the average welding heat input of two adjacent welding wires does not exceed 15kJ / cm, the longitudinal spacing between adjacent welding wires is 20mm. When the average welding heat input of two adjacent welding wires exceeds 15 kJ / cm, the longitudinal spacing between the adjacent welding wires increases by 1 mm for every 2 kJ / cm increase in the average heat input.

5. The non-longitudinal arrangement, large weld width three-wire submerged arc welding method according to claim 1, characterized in that, During the root pass and fill pass welding stages, the lateral offsets f2 and f3 of the second and third welding wires satisfy the following: When the remaining width of the bevel W ≤ 30mm, the values ​​of f2 and f3 are 8~12mm, and the maximum value does not exceed 12mm; When the remaining groove width W > 30mm, f2 and f3 increase synchronously with the increase of groove width and welding heat input, and f3 > f2.

6. The non-longitudinal arrangement, large weld width three-wire submerged arc welding method according to claim 1, characterized in that, During the cover welding stage, the lateral offsets c1 and c2 of the first and second welding wires satisfy the following: When the remaining width of the bevel W ≤ 30mm, the values ​​of c1 and c2 are 10~13mm, and the maximum value does not exceed 13mm; When the remaining groove width W > 30mm, c1 and c2 increase synchronously with the increase of groove width and welding heat input.

7. The non-longitudinal arrangement, large weld width three-wire submerged arc welding method according to claim 1, characterized in that, The first welding wire is connected to a DC welding power source, while the second and third welding wires are both connected to an AC welding power source.

8. The non-longitudinal arrangement, large weld width three-wire submerged arc welding method according to claim 1, characterized in that, The steel plate to be welded is low-alloy high-strength structural steel with an initial bevel width of 20 / 50mm; the welding wire diameter is 3.0 / 5.0mm, and it is equipped with smelting or sintering submerged arc welding flux.

9. The non-longitudinal arrangement, large weld width three-wire submerged arc welding method according to claim 1, characterized in that, After welding, the single weld bead completely covers the width of the bevel, the weld toe transitions smoothly, there are no undercuts or edge fusion defects, and ultrasonic non-destructive testing shows no internal defects exceeding the standard.

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