A hot-wire TIG + submerged arc hybrid welding method for high-strength steel conical workpieces

Abstract

A hot-wire TIG + submerged arc welding hybrid method for high-strength steel conical workpieces is disclosed. This method employs hot-wire TIG welding for the root pass (higher wire filler efficiency) and submerged arc welding for the filler and cover pass, with optimizations in part beveling, diameter matching, and welding posture. The beveling is a small-angle butt joint beveling with a gap, the weld beveling is a 30° V-shape, and the back side is blunt, avoiding dimensional interference while ensuring an appropriate beveling angle. During part assembly, the weld joint diameter is matched, rejecting products that do not meet requirements, and the diameter matching effect is improved by adjusting the gap. By adjusting the welding posture of the conical workpiece, a stable molten pool is formed, and the weld bead formation is uniform and symmetrical on both sides. During submerged arc welding, maintaining the posture effectively protects the molten pool and avoids incomplete fusion defects. The weld quality obtained by this invention meets the usage requirements of the conical workpiece, with no cracks, porosity, or incomplete fusion defects, and improves welding efficiency.

Description

Technical Field

[0001] This invention relates to the field of high-strength steel welding manufacturing, and is a hot-wire TIG + submerged arc composite welding method for high-strength steel conical workpieces with a wall thickness of 10mm or more. Background Technology

[0002] A conical workpiece is assembled from multiple conical parts welded together. The material is high-strength steel, and the butt weld between the conical parts has a wall thickness ≥10mm and a diameter ≥Φ500mm. Due to the harsh operating environment of the workpiece, strict requirements are placed on the weld quality, prohibiting cracks, porosity, or lack of fusion defects. The original method used tungsten inert gas (TIG) welding, employing multiple layers and passes (more than 10 layers) until the weld was complete. This resulted in long overall welding time, high equipment load, and high process control costs. To improve welding efficiency while ensuring welding quality, a new method needs to be developed to achieve efficient and stable welding of the conical workpiece weld. Hot-wire TIG welding and submerged arc welding are suitable for welding thick-walled workpieces with large filler wire amounts, and offer good weld quality. A composite welding method using hot-wire TIG welding for the root pass and submerged arc welding for the filler and cover passes is suitable for welding the aforementioned thick-walled, large-diameter conical workpiece. Since the two methods are suitable for different weld bevels and thicknesses, designing the welding bevel and welding process becomes a key issue for this composite welding method.

[0003] This invention combines the adaptability range of hot-wire TIG welding and submerged arc welding to weld shape, designs a special welding groove, and controls the weld misalignment and molten pool position during assembly and welding, thereby ensuring the welding quality of high-strength steel conical workpieces and improving welding efficiency.

[0004] A plasma + TIG welding method for ultra-high strength steel cylindrical parts is disclosed in invention patent CN114043108A. This method utilizes the high energy density and deep penetration of plasma to improve welding efficiency, and sets requirements for the precision of the parts and the control of the positioning weld points necessary to achieve this welding method. However, this method is not suitable for conical parts that cannot meet the requirements for machining precision and assembly clearance. Furthermore, plasma + TIG welding is less efficient than hot-wire TIG + submerged arc welding for conical workpieces with a wall thickness ≥10mm and a diameter ≥Φ500mm.

[0005] In the invention patent with publication number CN118848173A, a method for vertical welding of high-strength steel penetration butt welds is described. The method involves aligning the weld bevels of two high-strength steel workpieces to be welded, placing them vertically, performing argon-rich gas shielded welding, vertical welding, and then root cleaning welding to ensure the welding quality of workpieces with a thickness <40mm. This method is suitable for butt longitudinal welds where there is space for root cleaning welding on the back of the weld; it is not applicable to circumferential welds on conical workpieces. Summary of the Invention

[0006] To overcome the problems of low welding efficiency and difficulty in stabilizing welding over long periods of time in existing welding methods, this invention proposes a hot-wire TIG + submerged arc composite welding method for high-strength steel conical workpieces.

[0007] The conical workpiece involved in this invention is formed by sequentially welding a head ring, a conical section, and a tail ring. The specific process of the hot-wire TIG + submerged arc composite welding is as follows:

[0008] Step 1, Processing and cleaning the welding bevel:

[0009] The welding bevel is processed at the welding points where the head ring and the cone section are welded, and at the welding points where the cone section and the tail ring are welded.

[0010] The welding bevel structures at the locations where the head ring is welded to the conical section and the locations where the conical section is welded to the tail ring are identical and mirror-symmetrical.

[0011] Step 2, assembly of the conical workpiece:

[0012] The assembly of the conical workpiece involves sequentially assembling and positioning the head ring, conical segment, and tail ring to complete the assembly of the conical workpiece.

[0013] The difference in axiality between the tail ring, the cone section, and the head ring is less than 1 mm.

[0014] During the assembly of the conical workpiece, the tail ring is placed on a stable platform to ensure it is free from wobbling and slippage. The conical segment is placed on the upper end face of the tail ring, with a gap L2 between the contact surfaces of the tail ring and the conical segment. Argon arc welding is used for positioning and bottom sealing to obtain the assembled conical workpiece consisting of the tail ring and the conical segment.

[0015] Place the head ring 1 on the upper end face of the conical section of the weldment assembly, so that the lower end face of the head ring contacts the upper end face of the conical section, and leave a gap L1 between the contact surfaces of the head ring and the conical section; perform argon arc welding for positioning and bottom sealing welding to obtain the weldment assembly of the conical workpiece.

[0016] When assembling the head ring and the tapered section, compare the diameters of the two end faces of the weld, select the parts that satisfy Formula 1 for pairing, and then adjust the assembly gap L1 according to Formula 2 to achieve accurate diameter matching:

[0017] |Φ2-Φ1|≤0.5 (1)

[0018] L1=L0+(Φ2 / Φ1-1)T1 (2)

[0019] Wherein: Φ1 is the measured diameter of the welded end face of head ring 1, in mm; Φ2 is the measured diameter of the end face of the welded side of cone segment 2 and head ring 1, in mm; L1 is the gap to be controlled when assembling the butt weld of head ring 1 and cone segment 2, in mm; L0 is the theoretical gap for assembling the above butt weld, in mm; T1 is the theoretical distance from the top of the cone to the welded end face of head ring 1 and cone segment 2, in mm.

[0020] When assembling the conical section 2 and the tail ring 3, formula 3 should be satisfied, and the assembly clearance should be controlled according to formula 4:

[0021] |Φ4-Φ3|≤0.5 (3)

[0022] L2=L0+(Φ4 / Φ3-1)T2 (4)

[0023] Wherein: Φ3 is the measured diameter of the end face of the welded side of the cone segment 2 and the tail ring 3, in mm; Φ4 is the measured diameter of the welded end face of the tail ring 3, in mm; L2 is the gap that should be controlled when assembling the butt weld of the cone segment 2 and the tail ring 3, in mm; L0 is the theoretical gap for assembling the above butt weld, in mm; T2 is the theoretical distance from the top of the cone to the welded end face of the cone segment 2 and the tail ring 3, in mm.

[0024] Step 3: Clamp the weldment and adjust its orientation:

[0025] Transfer the assembled tapered workpiece to the platform of the rotary positioner, ensuring that the misalignment between the axis of the assembled workpiece and the axis of the rotary positioner is less than 2mm. Adjust the posture of the assembled workpiece so that its posture and the welding torch 4 meet the workpiece welding posture requirements for hot-wire TIG + submerged arc welding.

[0026] When adjusting the posture of the weldment assembly, rotate the conical workpiece along its own axis, and ensure that the generatrix of the welding point remains parallel to the ground during the rotation. Adjust the position of the welding torch so that the tip of the tungsten electrode is aligned with the center of the weld width.

[0027] Step 4, Hot-wire TIG soldering:

[0028] The assembled component has two weld seams: the first weld seam 5 between the head ring and the cone section, and the second weld seam 6 between the cone section and the tail ring. The two weld seams are then welded sequentially using hot-wire TIG welding to complete the hot-wire tungsten inert gas welding of both seams.

[0029] The specific process of hot-wire tungsten inert gas welding is as follows:

[0030] Ⅰ. The second weld between the cone section and the tail ring is welded using hot-wire TIG welding, performing a full circumference of continuous welding. After the welding torch passes the welding starting point again, the welding parameters are kept constant and welding continues for 10mm. Then, the attenuation mode is activated, causing the welding current to linearly decrease to the arc extinguishing state within 3 seconds. The argon shielding gas is terminated 6 seconds after the arc extinguishing state. The hot-wire TIG welding of the second weld is completed.

[0031] II. Repeat the process of welding the second weld to complete the hot wire TIG welding of the first weld.

[0032] The welding current for hot-wire TIG welding is 220A, the welding voltage is 10V, the hot wire voltage is 5.0V, the wire feed speed is 120m / h, and the welding speed is 7m / h.

[0033] Step 5, submerged arc welding:

[0034] Before submerged arc welding, the surfaces of each weld seam completed by hot wire TIG welding are ground and cleaned.

[0035] After cleaning, the second weld between the conical section and the tail ring is applied using submerged arc welding. After completing the second weld, the first weld between the head ring and the conical section is then applied. At this point, the welding of the conical workpiece is complete.

[0036] The submerged arc welding uses a welding current of 310A, a welding voltage of 30V, and a welding speed of 20m / h.

[0037] This invention uses hot-wire tungsten inert gas welding (TIG) for the root pass and submerged arc welding (SAW) for the filler pass, which has higher welding wire filling efficiency, to replace TIG welding for welding conical workpieces.

[0038] To achieve the above welding method, the present invention proposes the following requirements regarding part beveling, diameter matching, and welding posture:

[0039] 1. Design and process the weld bevel for tapered workpieces based on the characteristics of weld penetration and width in composite welding methods. Because a small-angle bevel with thick walls interferes with the welding torch nozzle, while a large-angle bevel increases the weld cross-sectional area and prolongs welding time, the design incorporates extensive production experience with similar products. Figure 4 The small-angle butt joint bevel shown has a 30° V-shaped bevel on one side of the weld face and a 2mm deep blunt edge on the back side, avoiding dimensional interference while ensuring an appropriate bevel angle. The above-mentioned welding bevels are machined on the head ring 1, cone section 2, and tail ring 3 in their pre-welding condition for assembly welding.

[0040] 2. Compare and match the diameter of the weld joint when assembling parts. Misalignment in the weld joint increases the difficulty of welding quality control and reduces the product forming accuracy. Therefore, when designing the bevel, the theoretical diameter of the joint between the parts on both sides of the weld should be equal. However, due to the inherent errors of the parts and the machining errors of the bevel, the diameters at the joint between the parts on both sides of the weld may differ. Therefore, during assembly, the diameters must first be compared to eliminate products that do not meet the requirements. Then, the gaps are adjusted to further improve the diameter matching effect and achieve the desired result. Figure 5 The assembly effect shown.

[0041] 3. Use a rotary positioner to adjust the welding posture of the conical workpiece. Weld a circumferential weld on the assembled conical workpiece. To ensure a uniform and stable molten pool during hot-wire TIG welding, rotate the conical workpiece along its own axis, ensuring that the generatrix of the welding point remains parallel to the ground throughout the rotation. Adjust the welding torch position so that the tungsten electrode tip is aligned with the center of the weld width. Figure 6 As shown in b, this ensures the formation of a stable molten pool and uniform, symmetrical weld bead formation on both sides. Maintaining this posture during submerged arc welding maximizes the flux's protective effect on the molten pool and avoids defects such as incomplete fusion caused by the welding torch deviating from the center of the weld.

[0042] This invention employs a combined hot-wire TIG welding and submerged arc welding method, which boasts welding efficiency more than three times higher than TIG welding, for welding high-strength steel conical workpieces with a wall thickness ≥10mm. Specific requirements were set for weld bevel design, assembly diameter control, and welding posture. Welding was performed according to the aforementioned combined welding method and control requirements. Verification results show that this method improves welding efficiency while ensuring the weld quality meets the usage requirements of the conical workpiece, with no cracks, porosity, or lack of fusion defects observed. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the headband structure.

[0044] Figure 2 This is a schematic diagram of the conical segment.

[0045] Figure 3 This is a schematic diagram of the tail ring structure.

[0046] Figure 4 This is a cross-sectional schematic diagram of the welding bevel.

[0047] Figure 5 This is the front view of the conical workpiece assembly structure.

[0048] Figure 6 This is a schematic diagram of the welding posture of a conical workpiece; among which, Figure 6 'a' is the main view. Figure 6 b is Figure 6A magnified view of part A in diagram a.

[0049] Figure 7 This is a flowchart of the present invention.

[0050] In the diagram: 1. Head ring; 2. Conical section; 3. Tail ring; 4. Welding torch; 5. First weld; 6. Second weld. Detailed Implementation

[0051] This embodiment describes a welding method for a conical workpiece. The conical workpiece is formed by sequentially welding a head ring 1, a conical segment 2, and a tail ring 3. The specific process is as follows:

[0052] Step 1, Processing and cleaning the welding bevel:

[0053] Machining at each welding end of the head ring and the cone section, and the cone section and the tail ring Figure 4 The welding bevels shown are identical and mirror-symmetrical. Before assembly, the welding bevels of each part must be cleaned until no visible oil, iron filings, or oxide scale remain to ensure proper assembly and welding.

[0054] Step 2, assembly of the conical workpiece:

[0055] Place the tail ring 3 on a stable platform, ensuring it is free from wobbling and slippage. Place the cone segment 2 on the upper end face of the tail ring 3, leaving a gap L2 between the contact surfaces of the tail ring and the cone segment; perform argon arc welding for positioning and bottom sealing to obtain a welded assembly consisting of the tail ring 3 and the cone segment 2.

[0056] Place the head ring 1 on the upper end face of the conical section of the weldment assembly, so that the lower end face of the head ring contacts the upper end face of the conical section, and leave a gap L1 between the contact surfaces of the head ring and the conical section; perform argon arc welding for positioning and bottom sealing welding to obtain the weldment assembly of the conical workpiece, and complete the assembly of the conical workpiece.

[0057] When assembling the head ring 1 and the cone section 2, compare the diameters of the two end faces of the weld, select the parts that satisfy Formula 1 for pairing, and then adjust the assembly gap L1 according to Formula 2 to achieve accurate diameter matching:

[0058] |Φ2-Φ1|≤0.5 (1)

[0059] L1=L0+(Φ2 / Φ1-1)T1 (2)

[0060] Wherein: Φ1 is the measured diameter of the welded end face of head ring 1, in mm; Φ2 is the measured diameter of the end face of the welded side of cone segment 2 and head ring 1, in mm; L1 is the gap to be controlled when assembling the butt weld of head ring 1 and cone segment 2, in mm; L0 is the theoretical gap for assembling the above butt weld, in mm; T1 is the theoretical distance from the top of the cone to the welded end face of head ring 1 and cone segment 2, in mm.

[0061] When assembling the conical section 2 and the tail ring 3, formula 3 should be satisfied, and the assembly clearance should be controlled according to formula 4:

[0062] |Φ4-Φ3|≤0.5 (3)

[0063] L2=L0+(Φ4 / Φ3-1)T2 (4)

[0064] in:

[0065] Φ3 is the measured diameter of the end face of the welded side of the cone segment 2 and the tail ring 3, in mm; Φ4 is the measured diameter of the welded end face of the tail ring 3, in mm; L2 is the gap that should be controlled when assembling the butt weld of the cone segment 2 and the tail ring 3, in mm; L0 is the theoretical gap for assembling the above butt weld, in mm; T2 is the theoretical distance from the top of the cone to the welded end face of the cone segment 2 and the tail ring 3, in mm.

[0066] The difference in axiality between the tail ring, the cone section, and the head ring is less than 1 mm.

[0067] Step 3: Clamp the weldment and adjust its orientation:

[0068] Transfer the assembled tapered workpiece to the platform of the rotary positioner, ensuring that the misalignment between the axis of the assembled workpiece and the axis of the rotary positioner is less than 2mm. Adjust the posture of the assembled workpiece so that its posture and the welding torch 4 meet the workpiece welding posture requirements for hot-wire TIG + submerged arc welding, as described above. Figure 6 a, Figure 6 As shown in b.

[0069] Step 4, hot-wire tungsten inert gas welding:

[0070] The assembled component has two weld seams: the first weld 5 between the head ring and the conical section, and the second weld 6 between the conical section and the tail ring. The two weld seams are applied sequentially using hot-wire tungsten inert gas welding. Specifically:

[0071] Ⅰ. The second weld between the cone section and the tail ring is welded using hot-wire TIG welding, and a full circle of continuous welding is performed. After the welding torch passes the welding starting point again, the welding parameters are kept unchanged and welding continues for 10mm. After that, the attenuation mode is activated, so that the welding current linearly decreases to the arc extinguishing state within 3s. The argon shielding gas is terminated 6s after the arc extinguishing state.

[0072] II. The first weld between the cone segment and the tail ring is welded using the same method as in I.

[0073] This completes the hot-wire tungsten inert gas welding of the two weld seams.

[0074] Step 5, submerged arc welding:

[0075] Before starting submerged arc welding, use an elastic grinding disc to grind the weld surface of the hot wire TIG weld to remove oxides and other impurities, and grind the remaining weld bevel smooth to avoid slag inclusions or lack of fusion defects between the transition layers of the two methods.

[0076] After cleaning, the second weld between the conical section and the tail ring was first welded using submerged arc welding, followed by the first weld between the head ring and the conical section. At this point, the welding of the conical workpiece was complete.

Claims

1. A hot-wire TIG + submerged arc composite welding method for high-strength steel conical workpieces, wherein the conical workpiece is formed by sequentially welding a head ring, a conical section, and a tail ring; characterized in that, The specific process is as follows: Step 1, Processing and cleaning the welding bevel: The welding bevel is processed at the welding points where the head ring and the cone section are welded, and at the welding points where the cone section and the tail ring are welded. Step 2, assembly of the conical workpiece: The assembly of the conical workpiece involves sequentially assembling and positioning the head ring, conical section, and tail ring to complete the assembly of the conical workpiece. The difference in axiality between the tail ring, the cone section and the head ring is <1mm; When assembling the head ring and the tapered section, compare the diameters of the two end faces of the weld, select the parts that satisfy Formula 1 for pairing, and then adjust the assembly gap L1 according to Formula 2 to achieve accurate diameter matching: |Φ2-Φ1|≤0.5 (1) L1=L0+(Φ2 / Φ1-1)T1 (2) Wherein: Φ1 is the measured diameter of the welded end face of head ring 1, in mm; Φ2 is the measured diameter of the end face of the welded side of the cone segment and head ring, in mm; L1 is the gap to be controlled during the assembly of the butt weld when assembling the head ring and cone segment, in mm; L0 is the theoretical gap for assembling the above butt weld, in mm; T1 is the theoretical distance from the top of the cone to the welded end face of the head ring and cone segment, in mm; When assembling the tapered section and the tail ring, Formula 3 should be satisfied, and the assembly clearance should be controlled according to Formula 4: |Φ4-Φ3|≤0.5 (3) L2=L0=(Φ4 / Φ3-1)T2 (4) Where: Φ3 is the measured diameter of the end face of the cone section and the tail ring welded together, in mm; Φ4 is the measured diameter of the tail ring welded end face, in mm; L2 is the gap that should be controlled when assembling the cone section and the tail ring, in mm; L0 is the theoretical gap for assembling the above-mentioned butt weld, in mm; T2 is the theoretical distance from the top of the cone to the welded end face of the cone section and the tail ring, in mm; Step 3: Clamp the weldment and adjust its orientation: Transfer the welded assembly of the conical workpiece to the platform of the rotary positioner, and ensure that the difference between the axis of the welded assembly and the axis of the rotary positioner is less than 2mm; adjust the posture of the welded assembly so that its posture and the welding torch meet the workpiece welding posture requirements of hot wire TIG + submerged arc welding. Step 4, Hot-wire TIG soldering: The assembled component has two weld seams: the first weld seam between the head ring and the cone section and the second weld seam between the cone section and the tail ring. The two weld seams are welded sequentially by hot wire TIG welding to complete the hot wire tungsten inert gas welding of the two weld seams. Step 5, submerged arc welding: Before submerged arc welding, the surfaces of each weld seam completed by hot wire TIG welding are ground and cleaned. After cleaning, the second weld between the cone section and the tail ring is applied using submerged arc welding. After the second weld is completed, the first weld between the head ring and the cone section is applied. Thus, the welding of the cone-shaped workpiece is completed.

2. The hot-wire TIG + submerged arc hybrid welding method for high-strength steel conical workpieces as described in claim 1, characterized in that, The welding bevel structures at the locations where the head ring is welded to the conical section and the locations where the conical section is welded to the tail ring are identical and mirror-symmetrical.

3. The hot-wire TIG + submerged arc hybrid welding method for high-strength steel conical workpieces as described in claim 1, characterized in that, When assembling the conical workpiece, the tail ring is placed on a stable platform to ensure that it does not wobble or slip; the conical segment is placed on the upper end face of the tail ring, and a gap L2 is left between the contact surfaces of the tail ring and the conical segment; argon arc welding is used for positioning and bottom sealing welding to obtain the welded assembly consisting of the tail ring and the conical segment. Place the head ring on the upper end face of the conical section of the weldment, so that the lower end face of the head ring contacts the upper end face of the conical section, and leave a gap L1 between the contact surfaces of the head ring and the conical section; perform argon arc welding for positioning and bottom sealing welding to obtain the weldment of the conical workpiece.

4. The hot-wire TIG + submerged arc hybrid welding method for high-strength steel conical workpieces as described in claim 1, characterized in that, When adjusting the posture of the weldment assembly, rotate the conical workpiece along its own axis, and ensure that the generatrix of the welding point remains parallel to the ground during the rotation. Adjust the position of the welding torch so that the tip of the tungsten electrode is aligned with the center of the weld width.

5. The hot-wire TIG + submerged arc hybrid welding method for high-strength steel conical workpieces as described in claim 1, characterized in that, The specific process of hot-wire tungsten inert gas welding is as follows: Ⅰ. Use hot wire TIG welding to weld the second weld between the cone and the tail ring, and perform continuous welding around the entire circle; after the welding torch passes the welding starting point again, keep the welding parameters unchanged and continue welding for 10mm, then start the attenuation mode so that the welding current linearly decreases to the arc extinguishing within 3s, and the argon shielding gas is terminated 6s after the arc extinguishing; the hot wire TIG welding of the second weld is completed. II. Repeat the welding process for the second weld to complete the hot wire TIG welding of the first weld.

6. The hot-wire TIG + submerged arc hybrid welding method for high-strength steel conical workpieces as described in claim 1, characterized in that, The welding current for hot-wire TIG welding is 220A, the welding voltage is 10V, the hot wire voltage is 5.0V, the wire feed speed is 120m / h, and the welding speed is 7m / h.

7. The hot-wire TIG + submerged arc hybrid welding method for high-strength steel conical workpieces as described in claim 1, characterized in that, The submerged arc welding uses a welding current of 310A, a welding voltage of 30V, and a welding speed of 20m / h.

Images