Ultra-narrow gap laser hybrid welding method

Abstract

According to the ultra-narrow gap laser hybrid welding method, laser beams are arranged in three rows, the middle row of laser beams is located in the center of a welding seam, the edges of grooves in the left side and the right side of the welding seam are each provided with a row of laser beams, in the welding process, the effective action width of the laser beams is controlled to be 6 mm, and two welding wires are symmetrically arranged on the left side and the right side of a narrow gap groove in a positive defocusing mode; the feeding position of a welding wire is located at the position 5-10 mm in front of a laser beam, and when the plate thickness T is smaller than or equal to 20 mm, the welding speed of 300-500 mm / min is adopted; and when the plate thickness T is larger than 20 mm, the welding speed of 100-300 mm / min is adopted, and a welding pool is protected through two paths of collaborative conveying protective gas. A multi-light-spot power-adjustable laser system, a double-wire cooperative feeding mechanism and a multi-path gas protection scheme are fused, and an efficient and stable narrow-gap welding technology system is constructed. And a series of problems such as incomplete fusion of the side wall of the welding groove, incomplete fusion of the center of the welding seam and defect of air holes of the welding seam which cause unqualified mechanical properties of the welding seam metal are effectively solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of offshore ship construction and design, and particularly relates to a super-narrow-gap laser composite welding method. BACKGROUND

[0002] In recent years, narrow-gap welding has been widely used in large equipment such as ships, pressure vessels, offshore platforms, etc. Narrow-gap welding has become the mainstream technology for thick plate welding due to its advantages of reducing the consumption of filler welding material, reducing welding heat input, and effectively suppressing the deformation of welded components. The existing laser composite welding technology has significant bottlenecks in practical application: 1. Traditional single-spot laser welding cannot adapt to the 6-10mm narrow-gap cladding requirement, and multiple problems such as side wall non-fusion, weld center non-penetration, and porosity often occur, affecting the performance of the welded structure; 2. The coordination between double-wire and laser is insufficient, and the position deviation and energy distribution imbalance of the welding wire lead to poor consistency of the weld formation, and defects such as undercut, non-fusion, and weld porosity are prone to occur; 3. The protective gas delivery path is single, and the whole process from the formation to the solidification of the weld pool cannot be effectively protected, resulting in frequent defects such as porosity and oxidation; 4. The laser beam power adjustment method is rigid, and it is difficult to match the different fusion requirements of the narrow-gap side wall, center, and other areas, and the adaptability is limited. SUMMARY

[0003] To solve the above problems, the present application provides a super-narrow-gap laser composite welding method, which aims to avoid the problems of weld slope side wall non-fusion, weld center non-penetration, and weld porosity defects leading to unqualified weld metal mechanical properties. The technical solution adopted is as follows: A super-narrow-gap laser composite welding method, the welding groove adopts an I-shaped groove, or the straight edge of the groove adopts a slight angle, and the width of the groove gap is 6mm-10mm.

[0004] The laser beam adopts a three-row layout, with 3 beams in each row, a total of 9 beams, the middle row of beams is located in the center of the weld, and one row of beams is arranged on each side of the weld, all 9 laser beams have independent power adjustment function, and different laser beam power is selected according to different welding layers of the backing welding or filler welding.

[0005] During the welding process, the effective action width of the laser beam is controlled to be 6mm, and the positive defocusing method is adopted, with a defocusing amount of 5mm-15mm, to adjust the defocusing amount to expand and reduce the action range of the laser beam.

[0006] A double-wire synchronous welding mode is adopted, and two welding wires are symmetrically arranged on the left and right sides of the narrow-gap groove, with a welding wire feeding position located 5mm-10mm in front of the laser beam, and a welding wire diameter of 1.2mm-1.6mm.

[0007] When the plate thickness T is ≤20mm, the welding speed of 300-500mm / min is adopted.

[0008] The protective gas is high-purity argon with purity ≥99.99%, and the two-way collaborative delivery of the protective gas is used to protect the welding pool, the first way of protective gas: the gas channel in the laser welding gun, the gas flow is 2-5L / min, the first way of protective gas mainly protects the laser lens and the instantaneous pool in the laser action area. The second way of protective gas: the gas feeding device on both sides of the groove is symmetrically arranged on both sides of the groove, and the action position lags behind the laser beam action point by 8-12mm area, the gas flow is 15-20L / min, and the second way of protective gas mainly protects the solidification area of the weld.

[0009] The above-mentioned ultra-narrow gap laser composite welding method is further, the width of the groove gap is 7mm-9mm.

[0010] The above-mentioned ultra-narrow gap laser composite welding method is further, the slight angle of the straight edge of the groove is not more than 5°.

[0011] The above-mentioned ultra-narrow gap laser composite welding method is further, the slight angle of the straight edge of the groove is 1°-3°.

[0012] The above-mentioned ultra-narrow gap laser composite welding method is further, the preheating needs to be carried out in advance before the welding wire feeding.

[0013] The above-mentioned ultra-narrow gap laser composite welding method is further, when the plate thickness T is ≤20mm, the welding speed of 300-400mm / min is adopted, and when the plate thickness T is >20mm, the welding speed of 200-300mm / min is adopted.

[0014] The above-mentioned ultra-narrow gap laser composite welding method is further, the gas flow of the gas channel in the laser welding gun is 3-4L / min.

[0015] The beneficial effects of the present application are: 1. The weld fusion quality is significantly improved. Through the scheme of independent adjustment of multiple light spot power, combined with the positive defocusing technology, the problem of non-fusion defect of the groove position on both sides of the narrow gap weld is completely solved.

[0016] 2. The thermal deformation is effectively controlled. The double-wire preheating design reduces the laser welding heat input, and the wide-range adjustable welding speed reduces the overall heat input accumulation of the welded component, and compared with the traditional welding method, the welding deformation amount is reduced by 30%-50%.

[0017] 3. Extremely low weld defect rate. The dual-path argon gas protection system, combined with the delayed protection effect of the shielding gas, isolates the weld pool from air interference throughout the welding process, reducing the probability of defects such as weld porosity and oxidation to below 0.5%.

[0018] 4. Wide range of applications. It can cover most narrow-gap welding scenarios for thick plates, and can perform high-quality welding with adjustable beam power for various base materials such as carbon steel, stainless steel, and high-strength steel. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the bevel of the present invention.

[0020] Figure 2 This is a schematic diagram of the laser beam distribution.

[0021] Figure 3 This is a schematic diagram of the beam power for drilling the bottom layer weld seam.

[0022] Figure 4 This is a schematic diagram of the beam power of the filler layer weld. Detailed Implementation

[0023] The invention will be further described with reference to the accompanying drawings.

[0024] A method for ultra-narrow gap laser hybrid welding includes: 1. Narrow gap bevel design: The welding bevel adopts an I-type bevel (or a slight angle on the straight edge of the bevel). The width of the bevel gap should be 6-10mm (7-9mm is the optimal welding gap). If a slight angle is used on the straight edge of the bevel, it should not exceed 5° (1°-3° is optimal). See details of the bevel design scheme. Figure 1 As shown, this bevel design significantly reduces the amount of welding material used and also lowers the cost of bevel processing. The narrow-gap bevel design provides a structural basis for subsequent welding process optimization.

[0025] 2. Multi-spot tunable laser system solution: The laser beams adopt a three-row layout, with a total of 9 beams (i.e., three rows of laser beams, 3 beams per row). See details. Figure 2 As shown, a row of laser beams is positioned at the center of the weld, with another row positioned along the bevel edges on both sides. All nine laser beams have independent power adjustment capabilities, allowing for the selection of different beam powers depending on the welding layer, such as the root pass or fill pass. During welding, the effective width of the laser beam is controlled at 6mm, employing a positive defocusing method. The defocusing amount is adjusted according to the plate thickness (typically within the range of 5-15mm). This adjustment expands and contracts the effective range of the laser beam, preventing incomplete fusion defects on both sides of the bevel and reducing the risk of porosity.

[0026] 3. Dual-wire collaborative feeding system: This system employs a dual-wire synchronous welding mode, with two welding wires symmetrically arranged on the left and right sides of a narrow-gap bevel. The welding wires are fed in 5-10mm in front of the laser beam. By preheating the welding wires, the laser heat input load is reduced. The welding wire diameter is selected based on the gap width, typically using 1.2-1.6mm welding wire to ensure compatibility between the welding wire and the bevel and high deposition efficiency.

[0027] 4. Welding process parameters: For detailed information on laser beam power selection, please refer to [link / reference]. Figure 3 As shown, during the actual welding process, fine adjustments can be made based on the weld pool deposition to achieve the optimal result of no welding defects. The welding speed range is 100-500 mm / min (in actual welding, a welding speed of 200-400 mm / min is more suitable). The welding speed adjustment range according to different plate thicknesses is as follows: when the plate thickness T≤20mm, a welding speed of 300-500 mm / min is used; when the plate thickness T>20mm, a welding speed of 100-300 mm / min is used.

[0028] 5. Multi-path gas protection system: High-purity argon gas with a purity ≥99.99% is used as the shielding gas. Two coordinating gas delivery paths protect the weld pool. The first shielding gas path is located within the laser welding torch, with a flow rate of 2-5 L / min (3-4 L / min provides optimal protection). This path primarily protects the laser lens and the instantaneous weld pool within the laser's effective area. The second shielding gas path consists of gas delivery devices symmetrically positioned on both sides of the bevel, acting 8-12 mm behind the laser beam's point of impact, with a flow rate of 15-20 L / min. This path focuses on protecting the solidification zone of the weld. This dual-path gas protection system achieves comprehensive protection of the weld pool from formation to solidification, eliminating blind spots throughout the entire process.

Claims

1. A method of ultra-narrow gap laser hybrid welding, characterized by, The welding groove adopts an I-shaped groove, or a slight angle is adopted for the straight edge of the groove, and the width of the groove gap is 6mm-10mm; The laser beams adopt a three-row layout, each row has three beams, a total of nine beams, the middle row of beams is located at the center of the weld, and one row of beams is arranged on each side of the groove edge, all nine laser beams have independent power adjustment function, and different laser beam powers are selected according to different welding layers of the backing welding or the filling welding; During the welding process, the effective action width of the laser beam is controlled to be 6mm, a positive defocusing mode is adopted, and the defocusing amount is 5mm-15mm, so as to expand and reduce the action range of the laser beam by adjusting the defocusing amount; A double-wire synchronous welding mode is adopted, and two welding wires are symmetrically arranged on the left and right sides of the narrow gap groove, the welding wire feeding position is located 5mm-10mm in front of the laser beam, and the welding wire diameter is 1.2mm-1.6mm; When the plate thickness T≤20mm, the welding speed of 300-500mm / min is adopted; when the plate thickness T>20mm, the welding speed of 100-300mm / min is adopted; The high-purity argon gas with a purity of ≥99.99% is selected as the protective gas, and the two-way collaborative delivery of the protective gas is adopted to protect the welding pool, the first way of protective gas: the laser welding gun is internally provided with a gas channel, the gas flow is 2-5L / min, and the first way of protective gas mainly protects the laser lens and the instantaneous molten pool in the laser action area; the second way of protective gas: the gas feeding device is symmetrically arranged on both sides of the groove, and the action position lags behind the laser beam action point by 8mm-12mm, the gas flow is 15-20L / min, and the second way of protective gas mainly protects the solidification area of the weld.

2. The method of ultra-narrow gap laser hybrid welding according to claim 1, characterized in that The width of the groove gap is 7mm-9mm.

3. The method of ultra-narrow gap laser hybrid welding according to claim 1, characterized in that, The slight angle adopted for the straight edge of the groove is not greater than 5°.

4. The method of ultra-narrow gap laser hybrid welding according to claim 3, characterized in that The slight angle adopted for the straight edge of the groove is 1°-3°.

5. The method of ultra-narrow gap laser hybrid welding according to claim 1, wherein Preheating is required before the welding wire feeding.

6. The method of ultra-narrow gap laser hybrid welding according to claim 1, wherein, When the plate thickness T≤20mm, the welding speed of 300-400mm / min is adopted; when the plate thickness T>20mm, the welding speed of 200-300mm / min is adopted.

7. The method of ultra-narrow gap laser hybrid welding according to claim 1, wherein The gas flow of the laser welding gun internal gas channel is 3-4L / min.

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