A large heat input combined welding method applicable to thick-walled high-strength steel

Abstract

This application belongs to the field of welding technology, and specifically discloses a large heat input combined welding method applicable to thick-walled high-strength steel, specifically: the steel plate to be welded is processed into an asymmetric double-sided V-groove, where the depth of the front groove is 30 mm to 40 mm. Then, electro-gas vertical welding is used to fill and weld the front groove, and the single-pass heat input is controlled below 300 kJ / cm. Finally, the back groove is filled and welded, and it is ensured that the single-pass heat input of the back groove does not exceed that of the front groove. This application uses an asymmetric double-sided V-groove to divide the steel plate to be welded into the front and back parts. By restricting the depth of the groove, the heat input of the fill welding is restricted, thereby avoiding a significant deterioration in the toughness of the heat-affected zone of the welded joint, and then effectively improving the mechanical properties of the welded joint, ensuring the long-term safe service of the deepwater jacket platform.

Description

Technical Field

[0001] This application belongs to the field of welding technology, and more specifically, it relates to a large heat input combination welding method applicable to thick-walled high-strength steel. Background Art

[0002] The jacket platform is an important infrastructure in the process of offshore oil and gas resource exploitation. In recent years, with the gradual development of offshore oil and gas resource exploitation in China towards low-temperature and deep-water areas, the thickness of the steel used for offshore platform jackets has been increasing, and the requirement for welding efficiency has also been increasing. At present, electric-gas vertical welding (EGW), as an efficient large heat input welding technology, has received more and more attention from technicians in this field.

[0003] As an extension of single-wire electric-gas vertical welding, the heat input of double-wire electric-gas vertical welding can reach more than 700 kJ / cm at most, and single-pass forming of plate thickness from 42 mm to 85 mm can be achieved. However, the significant increase in heat input will lead to the coarsening of grains in the heat-affected zone of its welded joint, thus deteriorating the impact toughness of the welded joint.

[0004] Patent CN109047997A discloses a welding method for double-wire electric-gas vertical welding applicable to ultra-large welding heat input, and CN115338516A discloses a welding method for double-wire electric-gas vertical welding applicable to high-strength ultra-thick steel plates. The impact toughness of the heat-affected zone of its welded joint can meet the requirement that the impact energy is ≥70 J at -40°C. However, considering that the offshore platform jacket is subjected to the impact of typhoons and waves for a long time during service, and coupled with the increasingly harsh low-temperature and deep-water environment, it is now required that the impact toughness of the heat-affected zone of the welded joint is ≥50 J at -60°C. The lowest temperature for impact toughness testing in the above publicly disclosed literatures is -40°C. Although there has been a significant improvement in welding efficiency, there is still the deficiency of the overall low low-temperature impact toughness of the heat-affected zone of the welded joint, and it is unknown whether the requirement of impact toughness at -60°C can be met.

[0005] In order to reduce the heat input of electric-gas vertical welding and further improve the impact toughness of the welded joint, CN116890180A discloses a welding method for the weld groove of high-strength steel thick plates and double-wire electric-gas vertical welding, the essence of which is to reduce the groove angle. This method can effectively reduce the welding heat input. However, on the one hand, due to the limitation of the swing amplitude of the welding torch during electric-gas vertical welding, the degree of reduction of the groove angle is restricted; on the other hand, the smaller the groove angle, the smaller the swing amplitude of the welding torch, which is likely to cause incomplete penetration at the root of the weld. In addition, when the minimum groove angle is reached, the heat input will increase with the increase of the wall thickness. Therefore, the effect of restricting the heat input by reducing the groove angle is still very limited. Summary of the Invention

[0006] In view of the deficiencies of the prior art, the present application provides a large heat input combined welding method applicable to thick-walled high-strength steel, aiming to solve the problem of poor impact toughness of the existing large heat input welding methods.

[0007] A large heat input combined welding method applicable to thick-walled high-strength steel provided by the present application is specifically as follows: the steel plate to be welded is processed into an asymmetric double-sided V-groove, where the depth of the front groove is 30 mm to 40 mm, then gas-electric vertical welding is used to fill and weld the front groove, and the single-pass heat input is controlled below 300 kJ / cm, and finally the back groove is filled and welded, and it is ensured that the single-pass heat input of the back groove does not exceed that of the front groove.

[0008] Through the above technical solution conceived by the present application, compared with the prior art, since the present application uses an asymmetric double-sided V-groove to divide the steel plate to be welded into the front and back parts, the heat input of the gas-electric vertical welding is restricted by restricting the depth of the groove, thereby avoiding a large deterioration of the toughness of the heat-affected zone of the welded joint, and thus effectively improving the mechanical properties of the welded joint.

[0009] As a further preference, the front groove angle is 30° to 40°, the back groove angle is 30° to 50°, and the depth of the root face is 3 mm to 5 mm.

[0010] As a further preference, when using gas-electric vertical welding to fill and weld the front groove, the welding current is 380 A to 460 A, the welding voltage is 38 V to 45 V, the welding speed is 3.5 cm / min to 4.5 cm / min, and the single-pass heat input is 200 kJ / cm to 300 kJ / cm.

[0011] As a further preference, when using gas-electric vertical welding to fill and weld the front groove, the wire dry elongation is 30 mm to 35 mm, and the shielding gas flow rate is 30 L / min to 35 L / min.

[0012] As a further preference, when using gas-electric vertical welding to fill and weld the front groove, the swing amplitude of the welding torch is controlled at 10 mm to 15 mm, and the unilateral dwell time is 0.3 s to 0.5 s.

[0013] As a further preference, when the depth H of the back groove 2 ≤ 25 mm, flux-cored wire arc welding is used for filling and welding.

[0014] As a further preference, when the depth of the back groove 25 < H 2 ≤ 50 mm, first flux-cored wire arc welding is used for filling and welding, and when the remaining groove depth h satisfies the following formula, gas-electric vertical welding is used for filling and welding,

[0015]

[0016] In the formula, h is the remaining groove depth, and H 2 is the back groove depth, and H 1 is the front groove depth, and α 1 is the front groove angle, and α 2 is the back groove angle.

[0017] As a further preference, when the back groove depth H 2 > 50 mm, submerged arc welding with three wires is first used for filling welding. When the remaining groove depth h satisfies the following formula, electro-gas vertical welding is used for filling welding.

[0018]

[0019] In the formula, h is the remaining groove depth, and H 2 is the back groove depth, and H 1 is the front groove depth, and α 1 is the front groove angle, and α 2 is the back groove angle.

[0020] As a further preference, when flux-cored wire arc welding is used for filling welding, the welding current is 160 A - 220 A, the welding voltage is 20 V - 23 V, the welding speed is 10 cm / min - 16 cm / min, the heat input is 10 kJ / cm - 20 kJ / cm, the dry extension of the welding wire is 12 mm - 15 mm, and the flow rate of the shielding gas is 15 L / min - 25 L / min.

[0021] As a further preference, when submerged arc welding with three wires is used for filling welding, the welding current of the front wire is 1160 A - 1380 A, and the welding voltage of the front wire is 32 V - 35 V; the welding current of the middle wire is 1100 A - 1280 A, and the welding voltage of the middle wire is 40 V - 42 V; the welding current of the back wire is 950 A - 1200 A, and the welding voltage of the back wire is 42 V - 46 V; the welding speed of the submerged arc welding with three wires is 35 cm / min - 81 cm / min, and the heat input is 90 kJ / cm - 260 kJ / cm.

[0022] Generally speaking, compared with the prior art by the above technical solutions conceived in this application, the following technical advantages are mainly possessed:

[0023] 1. This application uses an asymmetric double-sided V-groove to divide the steel plate to be welded into a front part and a back part. By restricting the groove depth to limit the heat input of the filling welding, the toughness of the heat-affected zone of the welded joint is prevented from deteriorating significantly, thereby effectively improving the mechanical properties of the welded joint and ensuring the long-term safe service of the deep-water jacket platform;

[0024] 2. In particular, by optimizing the welding parameters of the front groove, the present application can avoid excessive welding heat input while ensuring the welding efficiency, thereby preventing the degradation of the performance of the welded joint.

[0025] 3. At the same time, by optimizing the selection of the welding process for the back groove, the present application can select an appropriate welding process according to the depth of the back groove, thus avoiding excessive heat input and preventing the degradation of mechanical properties while ensuring the welding efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic diagram of the welding groove and weld beads provided in Embodiment 1 of the present application, where weld bead 1 is electro-gas welding, and weld beads 2-4 are flux-cored arc welding;

[0027] Figure 2 is a schematic diagram of the welding groove and weld beads provided in Embodiment 2 of the present application, where weld bead 1 is electro-gas welding, weld beads 2-4 are flux-cored arc welding, and weld bead 5 is electro-gas welding;

[0028] Figure 3 is a schematic diagram of the welding groove and weld beads in Embodiment 3 of the present application, where weld bead 1 is electro-gas welding, weld beads 2-5 are three-wire submerged arc welding, and weld bead 6 is electro-gas welding. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] In order to make the objectives, technical solutions, and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0030] As Figure 1 ~ shown, the present application provides a high-energy line combination welding method applicable to thick-walled high-strength steel, specifically as follows:

[0031] S1 For thick-walled high-strength steel with a thickness of 50 mm to 120 mm, first process the steel plate to be welded. The welding groove form adopts an asymmetric double-sided V-groove. The front groove angle α 1 is 30° to 40°, the front groove depth H 1 is fixed at 30 mm to 40 mm, the back groove angle α 2 is 30° to 50°, and a root face with a depth of 3 mm to 5 mm is reserved to prevent root burn-through due to heat accumulation during electro-gas welding;

[0032] S2 Assemble the steel plate to be welded and reserve a fit-up gap of 2 mm to 3 mm. Use manual arc welding to weld three ribs on the back of the steel plate to be welded to prevent deformation of the steel plate to be welded during electro-gas welding;

[0033] In S3, electro-gas welding is used to perform single-pass filling welding on the front groove to form a front weld. By fixing the depth of the front groove to limit the heat input of electro-gas welding, the single-pass heat input can be controlled below 300 kJ / cm, and preferably 200 kJ / cm to 300 kJ / cm.

[0034] In S4, the back rib plate is removed and back groove welding is carried out. One or more of flux-cored wire arc welding, electro-gas welding, or three-wire submerged arc welding are used to perform multi-pass filling welding on the back groove to form a back weld, and it is ensured that the single-pass heat input of the back groove does not exceed that of the front groove.

[0035] In this application, an asymmetric double-sided V-groove is used to divide the steel plate to be welded into a front part and a back part. By restricting the depth of the groove to limit the heat input of electro-gas welding, on the premise of ensuring the welding efficiency, embrittlement of the heat-affected zone of welding is prevented, and a large deterioration in the toughness of the heat-affected zone of the welded joint is avoided, thereby effectively improving the mechanical properties of the welded joint and ensuring the long-term safe service of the deepwater jacket platform.

[0036] Further, when using electro-gas welding to perform filling welding on the front groove, the welding current is 380 A to 460 A, the welding voltage is 38 V to 45 V, the welding speed is 3.5 cm / min to 4.5 cm / min, and the single-pass heat input is 200 kJ / cm to 300 kJ / cm; the wire diameter is preferably 1.6 mm, the wire dry elongation is 30 mm to 35 mm, and the shielding gas during welding is 100% CO 2 , and the shielding gas flow rate is 30 L / min to 35 L / min. In order to prevent incomplete fusion and defects during welding, oscillation needs to be added to the welding torch, and the oscillation amplitude of the welding torch is controlled within 10 mm to 15 mm, and the unilateral dwell time is 0.3 s to 0.5 s. By optimizing the parameters of the filling welding, it is possible to avoid excessive heat input during welding while ensuring the welding efficiency, resulting in a decline in the performance of the welded joint.

[0037] Further, considering that electro-gas welding is a single-pass forming welding technology dedicated to thick plates, when the plate thickness is too small, electro-gas welding is not required, and when the plate thickness is too large, directly using electro-gas welding for single-pass filling will result in excessive heat input, causing a decline in mechanical properties. Therefore, as the plate thickness increases, it is necessary to first fill a part with other welding processes, and then directly fill the remaining part with electro-gas welding to finish. At the same time, the greater the plate thickness, the more parts need to be filled with other processes, and the greater the depth of the back groove, the use of a welding process with a greater heat input is to improve the welding efficiency.

[0038] When the depth H of the back groove 2 ≤ 25 mm, only flux-cored wire arc welding is used for filling welding.

[0039] When the back groove depth 25 < H2 When it is ≤ 50 mm, first use flux-cored wire arc welding for filling welding. When the remaining groove depth h meets the requirements, use electro-gas welding for filling welding. To ensure the performance of the welded joint, the heat input of the back electro-gas welding should not exceed that of the front electro-gas welding. Since the heat input of electro-gas welding is determined by the cross-sectional area of the groove, it is necessary to satisfy that the remaining cross-sectional area S of the back groove 2 ≤ the cross-sectional area S of the front groove 1 , that is:

[0040]

[0041] In the formula, h is the remaining groove depth, H 2 is the back groove depth, H 1 is the front groove depth, α 1 is the front groove angle, α 2 is the back groove angle. According to formula (1), formula (2) can be derived

[0042]

[0043] Therefore, when the remaining groove depth h meets formula (2), use electro-gas welding for filling welding.

[0044] When the back groove depth H 2 > 50 mm, first use three-wire submerged arc welding for filling welding. When the remaining groove depth h meets formula (2), use electro-gas welding for filling welding.

[0045] Furthermore, when using flux-cored wire arc welding for filling welding, the welding current is 160 A - 220 A, the welding voltage is 20 V - 23 V, the welding speed is 10 cm / min - 16 cm / min, the heat input is 10 kJ / cm - 20 kJ / cm, the wire diameter is preferably 1.2 mm, the wire dry elongation is 12 mm - 15 mm, and the shielding gas during welding is 82% Ar + 18% CO 2 , and the shielding gas flow rate is 15 L / min - 25 L / min. By optimizing the parameters of the filling welding, it is possible to avoid excessive welding heat input while ensuring the welding efficiency, resulting in a decline in the performance of the welded joint.

[0046] Further, when performing filling welding by three-wire submerged arc welding, the front wire is tilted forward, the welding current range of the front wire is 1160 A to 1380 A, the welding voltage range of the front wire is 32 V to 35 V, and the wire diameter of the front wire is preferably 4.8 mm; the middle wire is vertical, the welding current range of the middle wire is 1100 A to 1280 A, the welding voltage range of the middle wire is 40 V to 42 V, and the wire diameter of the middle wire is 4.8 mm; the rear wire is tilted backward, the welding current range of the rear wire is 950 A to 1200 A, the welding voltage range of the rear wire is 42 V to 46 V, and the wire diameter of the rear wire is 6.4 mm; the welding speed of the three-wire submerged arc welding is 35 cm / min to 81 cm / min, and the heat input is 90 kJ / cm to 260 kJ / cm. By optimizing the parameters of the filling welding, it is possible to avoid excessive welding heat input while ensuring the welding efficiency, which may lead to a decline in the performance of the welded joint.

[0047] The following further illustrates the technical solutions provided by this application according to specific embodiments.

[0048] Example 1

[0049] This example takes a 50-mm thick high-strength steel plate as an example, and the specific steps are as follows:

[0050] Step 1: Preparation of the steel plate to be welded. The welding groove form uses an asymmetric double-sided V-groove, the front groove angle is 35°, the front groove depth H 1 is 30 mm, the back groove angle is 40°, and a root face of 3 mm is reserved;

[0051] Step 2: Assemble the steel plate to be welded and leave a 2-mm assembly gap. Use manual arc welding to weld three rib plates on the back of the steel plate to be welded to prevent the test plate from deforming during the electro-gas vertical welding process. The groove schematic diagram after assembly is as Figure 1 shown;

[0052] Step 3: Perform electro-gas vertical welding on the front to form a front weld. The welding current is 380 A, the welding voltage is 38 V, the welding speed is 3.8 cm / min, the wire diameter of the electro-gas vertical welding wire used is 1.6 mm, the wire dry elongation is 30 mm, and the shielding gas during welding is 100% CO 2 , the gas flow rate is 30 L / min, the oscillation amplitude of the welding torch is 12 mm, the unilateral dwell time is 0.4 s, and the single-pass heat input is about 205 kJ / cm;

[0053] Step 4: Remove the back rib plates and perform back groove welding. Since H 2 ≤ 25 mm, only flux-cored wire arc welding is used for filling, as Figure 1As shown, the back bead 2-4 is welded by flux-cored arc welding. The welding current range is 160 A, the welding voltage is 23 V, the welding speed is 12 cm / min. The diameter of the flux-cored arc welding wire used is 1.2 mm, the wire dry extension is 12 mm. During welding, the shielding gas is 82% Ar + 18% CO 2 , and the gas flow rate is 25 L / min. The heat input is about 16 kJ / cm.

[0054] Example 2

[0055] Same as Example 1, only in Step 4, the welding current range is 200 A, the welding voltage is 20 V, the welding speed is 10 cm / min, the gas flow rate is 20 L / min, and the heat input is about 21 kJ / cm.

[0056] Example 3

[0057] Same as Example 1, only in Step 4, the welding current range is 220 A, the welding voltage is 21 V, the welding speed is 10 cm / min, the gas flow rate is 22 L / min, and the heat input is about 25 kJ / cm.

[0058] Example 4

[0059] In this example, an 80-mm thick high-strength steel plate is taken as an example. The specific steps are as follows:

[0060] Step 1: Preparation of the steel plate to be welded. The welding groove form is an asymmetric double-sided V-groove. The front groove angle is 30°, the front groove depth H 1 is 35 mm, the back groove angle is 30°, and a root face of 4 mm is reserved;

[0061] Step 2: The steel plate to be welded is assembled with a 2-mm assembly gap reserved. Manual arc welding is used to weld three rib plates on the back of the steel plate to be welded to prevent the test plate from deforming during electro-gas vertical welding. The schematic diagram of the groove after assembly is as Figure 2 shown;

[0062] Step 3: Perform electro-gas vertical welding on the front to form the front weld. The welding current is 400 A, the welding voltage is 42 V, the welding speed is 4 cm / min. The diameter of the electro-gas vertical welding wire used is 1.6 mm, the wire dry extension is 35 mm. During welding, the shielding gas is 100% CO 2 , the gas flow rate is 32 L / min, the oscillation amplitude of the welding torch is 10 mm, the unilateral dwell time is 0.3 s, and the single-pass heat input is about 226 kJ / cm;

[0063] Step 4: Remove the back rib plates and perform back groove welding. Since 25 < H 2When it is ≤ 50 mm, therefore, flux-cored arc welding is first used for filling. According to the calculation of formula (2), when the remaining groove depth h ≤ 19.6 mm, electro-gas welding is then used for filling. As Figure 2 shown, for weld beads 2 - 4, flux-cored arc welding is used. The welding current range is 220 A, the welding voltage is 22 V, the welding speed is 12 cm / min. The wire diameter of the flux-cored wire used for flux-cored arc welding is 1.2 mm, the wire dry extension is 12 mm. During welding, the shielding gas is 82% Ar + 18% CO 2 , the gas flow rate is 20 L / min, and the heat input is about 21 kJ / cm;

[0064] Measure the remaining groove depth. If it is less than 19.6 mm, then for weld bead 5, electro-gas welding is used. The welding current range is 380 A, the welding voltage is 40 V, the welding speed is 4.5 cm / min, and the other parameters are the same as those of the electro-gas welding for the front groove. If it is greater than 19.6 mm, continue to use flux-cored arc welding for filling until it is less than 19.6 mm and then use electro-gas welding for filling.

[0065] Example 5

[0066] Same as Example 4, only in step 3, when using flux-cored arc welding for filling, the welding current is 160 A, the welding voltage is 20 V, the welding speed is 12 cm / min, the gas flow rate is 25 L / min, and the heat input is about 14 kJ / cm.

[0067] Example 6

[0068] Same as Example 4, only in step 3, when using flux-cored arc welding for filling, the welding current is 220 A, the welding voltage is 23 V, the welding speed is 10 cm / min, the gas flow rate is 22 L / min, and the heat input is about 27 kJ / cm.

[0069] Example 7

[0070] Taking a 110 - mm thick high-strength steel plate as an example in this embodiment, the specific steps are as follows:

[0071] Step 1: Prepare the steel plate to be welded. The welding groove form adopts an asymmetric double-sided V-groove. The front groove angle is 40°, the front groove depth H 1 is 40 mm, the back groove angle is 50°, and the reserved root face is 5 mm;

[0072] Step 2: Assemble the steel plate to be welded and reserve a 3 - mm assembly gap. Use manual arc welding to weld three ribs on the back of the steel plate to be welded to prevent the test plate from deforming during the electro-gas welding process. The schematic diagram of the groove after assembly is as Figure 3 shown;

[0073] Step 3: Perform vertical electro-gas welding on the front side to form a front weld seam. The welding current is 450 A, the welding voltage is 44 V, and the welding speed is 4.2 cm / min. The diameter of the electro-gas welding wire used is 1.6 mm, the wire dry elongation is 30 mm, and the shielding gas during welding is 100% CO 2 , and the gas flow rate is 3.5 L / min. The amplitude of the welding torch oscillation is 15 mm, the dwell time on each side is 0.5 s, and the single-pass heat input is approximately 254 kJ / cm;

[0074] Step 4: Remove the back rib plate and perform back groove welding. Since H 2 > 50 mm, first, submerged arc welding with three wires is used for filling. According to the calculation of formula (2), when the remaining groove depth h ≤ 16.6 mm, electro-gas welding is then used for filling. As Figure 3 shown, the back weld beads 2 - 5 are welded by submerged arc welding with three wires. The welding current range of the front wire is 1280 A, the welding voltage of the front wire is 34 V, and the diameter of the electrode wire of the front wire is 4.8 mm; the welding current range of the middle wire is 1160 A, the welding voltage range of the middle wire is 42 V, and the diameter of the electrode wire of the middle wire is 4.8 mm; the electrode welding current of the back wire is 950 A, the welding voltage of the back wire is 2 V, and the diameter of the electrode wire of the back wire is 6.4 mm. The welding speed is 45 cm / min, and the heat input is approximately 160 kJ / cm;

[0075] Measure the remaining groove depth. If it is less than 16.6 mm, then weld bead 6 uses electro-gas welding. The welding current range is 380 A, the welding voltage is 45 V, the welding speed is 4.5 cm / min, and the other parameters are the same as those of the electro-gas welding for the front groove. If it is greater than 16.6 mm, continue to fill with submerged arc welding with three wires until it is less than 16.6 mm and then use electro-gas welding for filling.

[0076] Example 8

[0077] Same as Example 7, only in Step 4, when filling with submerged arc welding with three wires, the welding current range of the front wire is 1380 A, the welding voltage of the front wire is 35 V; the welding current range of the middle wire is 1100 A, the welding voltage range of the middle wire is 40 V; the electrode welding current of the back wire is 1200 A, the welding voltage of the back wire is 46 V, the welding speed is 60 cm / min, and the heat input is approximately 135 kJ / cm;

[0078] Example 9

[0079] Same as Example 7, only in Step 4, during the multi-wire submerged arc welding filling, the welding current range of the front wire is 1160 A, and the welding voltage of the front wire is 33 V; the welding current range of the middle wire is 1280 A, and the welding voltage range of the middle wire is 41 V; the electrode welding current of the rear wire is 1100 A, the welding voltage of the rear wire is 44 V, the welding speed is 50 cm / min, and the heat input is about 150 kJ / cm.

[0080] Those skilled in the art can easily understand that the above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A high-energy input combined welding method suitable for thick-walled high-strength steel, characterized in that: The high-energy input combined welding method is as follows: the steel plate to be welded is processed into an asymmetric double-sided V-shaped groove, wherein the depth of the front groove is 30 mm to 40 mm, and then the front groove is filled and welded by gas-electric vertical welding, and the single-pass heat input is controlled below 300 kJ / cm, and finally the back groove is filled and welded, and the single-pass heat input of the back groove is ensured not to exceed the single-pass heat input of the front groove, wherein: When the depth of the back groove H2≤25mm, flux-cored arc welding is used for filling welding; When the back groove depth is 25<H2≤50mm, flux-cored arc welding is first used for filling welding. When the remaining groove depth h satisfies the following formula, gas-electric vertical welding is used for filling welding. Where, h is the remaining groove depth, H2 is the back groove depth, H1 is the front groove depth, α1 is the front groove angle, and α2 is the back groove angle; When the back groove depth H2>50mm, three-wire submerged arc welding is first used for filling welding. When the remaining groove depth h satisfies the following formula, gas-electric vertical welding is used for filling welding. Where h is the remaining groove depth, H2 is the back groove depth, H1 is the front groove depth, α1 is the front groove angle, and α2 is the back groove angle.

2. The high-energy input combined welding method according to claim 1, characterized in that: The front bevel angle is 30°~40°, the back bevel angle is 30°~50°, and the depth of the blunt edge is 3mm~5mm.

3. The high-energy input combined welding method according to claim 1, characterized in that: When gas-electric vertical welding is used for filling welding of the front groove, the welding current is 380A~460A, the welding voltage is 38V~45V, the welding speed is 3.5cm / min~4.5cm / min, and the single-pass heat input is 200kJ / cm~300kJ / cm.

4. The high-energy input combined welding method according to claim 1, characterized in that: When gas-electric vertical welding is used for filling welding of the front groove, the dry extension length of the welding wire is 30mm~35mm, and the flow rate of the shielding gas is 30L / min~35L / min.

5. The high-energy input combined welding method according to claim 1, characterized in that: When using gas-electric vertical welding to fill the front groove, the swing amplitude of the welding gun is controlled at 10mm~15mm, and the single-side dwell time is 0.3s~0.5s.

6. The high-energy input combined welding method according to claim 1, characterized in that: When flux-cored arc welding is used for filling welding, the welding current is 160A~220A, the welding voltage is 20V~23V, the welding speed is 10cm / min~16cm / min, the heat input is 10kJ / cm~20kJ / cm, the wire dry extension length is 12mm~15mm, and the shielding gas flow rate is 15L / min~25L / min.

7. The high-energy input combined welding method according to claim 6, characterized in that: When three-wire submerged arc welding is used for filling welding, the welding current of the front wire is 1160A~1380A, and the welding voltage of the front wire is 32V~35V; the welding current of the middle wire is 1100A~1280A, and the welding voltage of the middle wire is 40V~42V; the welding current of the rear wire is 950A~1200A, and the welding voltage of the rear wire is 42V~46V; the welding speed of three-wire submerged arc welding is 35cm / min~81cm / min, and the heat input is 90kJ / cm~260kJ / cm.

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