Double-beam laser and multistage indirect electric arc combined heat source efficient welding method

Abstract

The invention provides a double-beam laser and multi-stage indirect arc combined heat source efficient welding method, the combined heat source comprises a common single laser beam, a multi-stage indirect arc and a scanning laser beam which are arranged in sequence, and the welding method comprises the following steps that before welding, a groove with a certain angle and a penetrating gap is formed in a super-large thick-wall component; the groove of the component is sequentially divided into a truncated edge penetrating area and a filling and covering area from bottom to top in the thickness direction. During welding, one-time welding double-face forming of the ultra-large thick-wall component is achieved through the synergistic effect of multiple heat sources; wherein the common single laser beam is used for completely penetrating through the truncated edge penetrating area for penetrating welding; the multi-stage indirect arc is used for performing graded filling on the filling coverage area; and the scanning laser beam is used for fully stirring the molten pool in the filling and covering area, so that molten pool metal and the side wall of the groove are completely fused, and good surface forming is obtained. The technical problem of single-pass high-quality welding bottleneck of the ultra-large thick-wall component with the thickness being 30 mm or above is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of composite welding, and in particular to a high-efficiency welding method using a dual-beam laser and a multi-stage indirect arc combined heat source. Background Art

[0002] With the increasing demand for welding thick-walled components (over 20mm thick) in sectors such as large ships, nuclear power plants, oil pipelines, and boiler manufacturing, there is an urgent need to overcome the bottleneck of single-pass weldable thickness while ensuring good joint quality in laser welding. Indirect arc welding is a novel welding heat source that generates an indirect arc through discharge between multiple wires. In principle, this method, unlike traditional arc welding, which involves discharge between wires and the base material, effectively controls molten pool overheating and improves wire deposition efficiency. Therefore, combining a high-energy laser beam with an indirect arc welding method can achieve even better fill performance than conventional laser arc hybrid welding. Therefore, while maintaining constant laser power and blunt edge, indirect arc laser welding can completely fill a larger groove with a single weld, further increasing the maximum weldable thickness in a single pass.

[0003] However, when the thickness of a single-pass weld reaches 30mm or more, simply increasing the arc power between multiple wires to increase the amount of wire deposition to ensure a full weld also has its limits. For example, if the current between wires exceeds the limit, fuse instability or even discharge explosion will occur, seriously affecting the weld formation, joint performance and microstructure. If the filler metal requirement is reduced by reducing the groove angle, it may be difficult for the laser and arc heat sources to completely cover the groove, resulting in side wall unfused defects. If the groove size remains unchanged and the blunt edge thickness is increased, a higher laser line energy is required for single-pass welding to achieve a greater penetration effect. However, this means that the energy interaction in the keyhole is more intense, the thermal field gradient of the molten pool increases, and interfering substances such as plume, smoke, and spatter increase, thereby causing a series of welding manufacturing problems such as increased porosity tendency, decreased forming stability, reduced penetration conversion efficiency, increased welding deformation, and weakened joint performance. Summary of the Invention

[0004] The purpose of the present invention is to provide a dual-beam laser and multi-stage indirect arc combined heat source efficient welding method, which solves the technical problem of the bottleneck of single-pass high-quality welding of ultra-large thick-walled components with a thickness of more than 30 mm.

[0005] In order to solve the above technical problems, the technical solutions of the present invention are as follows: The present invention provides a high-efficiency welding method using a combined heat source of dual-beam laser and multi-stage indirect arc. The combined heat source comprises a common single laser beam, a multi-stage indirect arc, and a scanning laser beam arranged in sequence. The welding method comprises the following steps: before welding, a groove with a certain angle and a penetration gap is first opened on an ultra-large thick-walled component; the groove of the ultra-large thick-walled component is divided into a blunt edge penetration area and a filling coverage area from bottom to top along the thickness direction; during welding, double-sided forming of the ultra-large thick-walled component is achieved through the coordinated action of multiple heat sources in one welding; wherein the common single laser beam is used to completely penetrate the blunt edge penetration area to perform penetration welding on the gap at the blunt edge; the multi-stage indirect arc is used to perform graded filling of the filling coverage area; and the scanning laser beam is used to fully stir the molten pool in the filling coverage area to completely fuse the molten pool metal with the groove side wall and obtain good surface forming.

[0006] Furthermore, the scanning laser beam, the multi-stage indirect arc and the ordinary single laser beam are arranged in sequence along the welding direction.

[0007] Furthermore, the multi-stage indirect arc adopts two or more stages, and the respective positions of the multi-stage indirect arc are successively raised from the bottom of the groove.

[0008] Furthermore, the indirect arc uses double wires or multiple wires, and can discharge only between the welding wires, or can discharge simultaneously between the welding wires and between the welding wire and the base material.

[0009] Furthermore, the groove adopts a "Y"-shaped groove or a "U"-shaped groove with a penetration gap.

[0010] Furthermore, the gap width at the blunt edge of the groove is less than 1 mm.

[0011] Furthermore, the thickness of the blunt edge penetration area ranges from 10 to 20 mm.

[0012] Furthermore, the thickness of the filling covering area ranges from 10 to 30 mm.

[0013] Compared with the prior art, the present invention has at least the following beneficial effects: 1. The present invention uses three heat sources to weld three sections of the ultra-large thick-walled component in the thickness direction. This effectively breaks through the weldable thickness limit of laser arc hybrid welding without increasing the energy of a single laser beam line, and to a certain extent reduces the dependence on ultra-high power lasers when welding ultra-large thick-walled components.

[0014] 2. The present invention supports the use of multi-stage indirect arc joint filling and small-angle groove forms, which can effectively increase the metal filling amount and groove depth. Therefore, there is no need to increase the welding wire deposition amount by increasing the arc power, and effectively avoid the phenomenon of fuse instability caused by excessive inter-wire current, or even discharge explosion, which affects the weld formation, joint performance and microstructure.

[0015] 3. The present invention does not rely on simply increasing the energy of a single laser line to achieve greater penetration, so it will not intensify the energy interaction within the keyhole, and can effectively suppress the increase in the thermal field gradient of the molten pool and the large-scale production of interfering substances such as plume, smoke, and spatter. Therefore, it can solve a series of welding manufacturing problems caused by high-power laser welding, such as increased porosity tendency, decreased forming stability, reduced penetration conversion efficiency, increased welding deformation, and weakened joint performance.

[0016] 4. The scanning laser welding adopted in the present invention effectively stirs the indirect arc molten pool, which can solve the side wall unfused defects caused by the indirect arc molten pool temperature being too low, and can accelerate the precipitation of process-type bubbles and reduce the tendency of process-type porosity defects by stirring the molten pool. At the same time, the stirring of the molten pool can continuously break the newly generated dendrites at the solid-liquid interface, which plays a role in refining the grains, homogenizing the structure / composition, reducing the precipitation of brittle items, and thus effectively improving the mechanical properties of the joint.

[0017] The present invention supports the use of a small-angle "Y"-shaped groove or a small-gap "U"-shaped groove with a certain angle. During welding, the cross-section of the molten pool presents a uniform transition shape with a wide top and narrow bottom. This is beneficial for floating process-related pores during welding and reducing pore defects. In addition, since the keyhole tends to expand outward under the action of internal metal vapor pressure during welding, the "wide top and narrow bottom" uniform transition molten pool shape just creates a "trumpet" shape in the laser keyhole, which opens wider upward. This helps release the ejected material inside the keyhole during laser welding of thick-walled components, thereby reducing the loss and fluctuation of laser energy. Therefore, it has a good effect on improving the stability of laser welding of ultra-thick-walled components.

[0018] 6. The indirect arc of the present invention can be discharged only between the welding wires, or it can be discharged simultaneously between the welding wires and between the welding wires and the base material. Therefore, the indirect arc can better control the overheating of the molten pool and effectively improve the welding wire deposition amount and deposition efficiency.

[0019] 7. The positions of the multi-stage indirect arcs of the present invention are successively raised from the bottom of the groove, which can effectively reduce the impact of the falling molten droplets, reduce the breakage and splashing of the molten droplets, and thus make the welding process more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 Schematic diagram of the structure when welding using the welding method of the present invention; wherein the direction of the arrow indicates the welding direction; Figure 2 It is a right side view schematic diagram of welding using the welding method of the present invention.

[0022] mark: 1- Ordinary single laser beam; 2- Multi-level indirect arc; 3- Scanning laser beam; 4- Blunt edge penetration area; 5- Filling coverage area. DETAILED DESCRIPTION

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0024] This embodiment provides a dual-beam laser and multi-stage indirect arc combined heat source efficient welding method, please refer to Figure 1-2 As shown, the combined heat source includes a common single laser beam 1, a multi-stage indirect arc 2, and a scanning laser beam 3 arranged in sequence, and the welding method includes the following steps: Before welding, a groove with a certain angle and penetration gap is opened on the super thick wall component; The groove of the ultra-large thick-walled component is divided into a blunt edge penetration area 4 and a filling and covering area 5 from bottom to top along the thickness direction; During welding, the synergistic effect of multiple heat sources is used to achieve double-sided forming of ultra-large thick-walled components through one-time welding; Among them, the ordinary single laser beam 1 is used to completely penetrate the blunt edge penetration area 4 to perform penetrating welding on the gap at the blunt edge; the multi-stage indirect arc 2 is used to graded fill the filling coverage area 5; the scanning laser beam 3 is used to fully stir the molten pool in the filling coverage area 5 so that the molten pool metal is completely fused with the groove side wall and obtain good surface forming.

[0025] The gap width at the blunt edge of the groove is generally less than 1mm; the thickness of the blunt-edge penetration area 4 ranges from 10-20mm; and the thickness of the filling coverage area 5 ranges from 10-30mm. Furthermore, the gap width at the upper end of the groove is generally less than 10mm. The single-side angle of a "U"-shaped groove is 0-5°, and that of a small V (upper Y) groove is 4-15°. The single-side angle is the angle between the groove surface and the vertical. The thickness range of each area can be determined based on the laser spot diameter, the scanning laser's swing radius, and the arc's spread coverage.

[0026] In addition, it should be noted that the present invention limits the specific application scenarios of this method, that is, its application in scenarios of small angles, high depths (V parts) and narrow gap grooves of ultra-large thick-walled components (above 30 mm).

[0027] Specific example description: 1. Multi-heat source zoned welding process based on "Y" type groove 1. Arrangement order of composite heat sources Composite heat source: It is composed of 1 ordinary single laser beam, 1 set of multi-level indirect arc and 1 scanning laser beam; Along the welding direction, they are: scanning laser beam 3, multi-level indirect arc 2 and ordinary single laser beam 1.

[0028] 2. Slope opening and area division A small-angle "Y"-shaped groove is opened on a 30mm thick extra-thick-walled component, leaving a 0.6mm gap at the blunt edge, and ensuring that the corresponding groove cross-sectional area is smaller than the maximum fillable amount / area of the arc.

[0029] Along the groove thickness direction from bottom to top, it is divided into: Blunt edge penetration area (thickness 10mm), the penetration gap at the bottom of the groove; The filling covering area (thickness 20mm) is located in the filling fusion area in the middle and upper part of the groove.

[0030] 3.Multi-heat source collaborative welding Ordinary single laser beam: Focused on blunt edge penetration area 4, penetrating 10mm blunt edge to form penetrating welding; Multi-stage indirect arc: using two-stage indirect arc, and raising them in sequence, to perform graded filling of the filling coverage area 5; Scanning laser beam: fully stirs the molten pool in the filling coverage area 5 so that the molten pool metal is completely fused with the groove side wall and a good surface forming is obtained.

[0031] 2. Welding process based on “U” groove with gap 1. Arrangement order of composite heat sources Composite heat source: It is composed of 1 ordinary single laser beam, 1 group of multi-level indirect arc and 1 group of scanning laser beam; Along the welding direction, they are: scanning laser beam 3, multi-level indirect arc 2 and ordinary single laser beam 1.

[0032] 2. Slope opening and area division Processing a narrow-gap, small-angle "U"-shaped groove on a 45mm thick ultra-thick-walled component. The blunt edge gap is 0.7mm, and the corresponding groove cross-sectional area is smaller than the maximum fillable volume / area of the arc. Along the groove thickness direction from bottom to top, it is divided into: Blunt edge penetration area (thickness 15mm), the penetration gap at the bottom of the groove; Filling covering area (30mm thickness), located in the filling fusion area in the middle and upper part of the groove; 3.Multi-heat source collaborative welding Ordinary single laser beam: Focused on blunt edge penetration area 4, penetrating 15mm blunt edge to form penetrating welding; Multi-stage indirect arc: three-stage indirect arc is used and raised in sequence to fill the filling coverage area 5 in stages; Scanning laser beam: fully stirs the molten pool in the filling coverage area 5 so that the molten pool metal is completely fused with the groove side wall and a good surface forming is obtained.

[0033] The above method uses three heat sources: ordinary single laser beam 1, multi-level indirect arc 2 and scanning laser beam 3 to weld three sections in the thickness direction of ultra-large thick-walled components. Combined with the design of small-angle "Y"-shaped or narrow-gap "U"-shaped groove, without increasing the energy of a single laser beam line, it not only breaks through the weldable thickness limit of laser arc hybrid welding and reduces the dependence on ultra-high power lasers, but also avoids a system problem caused by overheating of the molten pool by controlling the metal filling amount.

[0034] At the same time, the scanning laser welding adopted in the present invention effectively stirs the indirect arc molten pool, which can solve the side wall unfused defects caused by the indirect arc molten pool temperature being too low, and can accelerate the precipitation of process-type bubbles and reduce the tendency of process-type porosity defects by stirring the molten pool. At the same time, the molten pool stirring can also continuously break the newly generated dendrites at the solid-liquid interface, which plays a role in refining the grains, homogenizing the structure / composition, reducing the precipitation of brittle items, and thus effectively improving the mechanical properties of the joint.

Claims

1. A high-efficiency welding method using a dual-beam laser and multi-stage indirect arc combined heat source, characterized in that: The combined heat source includes a conventional single laser beam, a multi-stage indirect arc, and a scanning laser beam arranged in sequence, and the welding method includes the following steps: Before welding, a groove with a certain angle and penetration gap is opened on the super thick wall component; Dividing the groove of the ultra-large thick-walled component into a blunt edge penetration area and a filling and covering area from bottom to top along the thickness direction; During welding, the synergistic effect of multiple heat sources is used to achieve double-sided forming of ultra-large thick-walled components through one-time welding; Among them, the ordinary single laser beam is used to completely penetrate the blunt edge penetration area to perform penetrating welding on the gap at the blunt edge; the multi-stage indirect arc is used to graded fill the filling coverage area; the scanning laser beam is used to fully stir the molten pool in the filling coverage area so that the molten pool metal is completely fused with the groove side wall and obtain good surface forming.

2. The high-efficiency welding method of dual-beam laser and multi-stage indirect arc combined heat source according to claim 1 is characterized in that: The scanning laser beam, the multi-stage indirect arc and the ordinary single laser beam are arranged in sequence along the welding direction.

3. The high-efficiency welding method of dual-beam laser and multi-stage indirect arc combined heat source according to claim 1 is characterized in that: The multi-stage indirect arc adopts two or more stages, and the respective positions of the multi-stage indirect arc are successively raised from the bottom of the groove.

4. The high-efficiency welding method of dual-beam laser and multi-stage indirect arc combined heat source according to claim 1 is characterized in that: The indirect arc uses double wires or multiple wires, and can discharge only between the welding wires, or can discharge simultaneously between the welding wires and between the welding wire and the base material.

5. The high-efficiency welding method of dual-beam laser and multi-stage indirect arc combined heat source according to claim 1 is characterized in that: The groove adopts a "Y"-shaped groove or a "U"-shaped groove with a penetration gap.

6. The high-efficiency welding method of dual-beam laser and multi-stage indirect arc combined heat source according to claim 1 is characterized in that: The gap width at the blunt edge of the groove is less than 1 mm.

7. The high-efficiency welding method of dual-beam laser and multi-stage indirect arc combined heat source according to claim 1 is characterized in that: The thickness of the blunt edge penetration area ranges from 10 to 20 mm.

8. The high-efficiency welding method of dual-beam laser and multi-stage indirect arc combined heat source according to claim 1 is characterized in that: The thickness of the filling covering area ranges from 10 to 30 mm.

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