Ultra-large type tube plate tailor-welding deformation control method based on positive and negative sequence welding

Abstract

The invention belongs to the technical field of pipe plate tailor-welding deformation control, and particularly discloses an ultra-large type pipe plate tailor-welding deformation control method based on positive and negative sequence welding, which is used for solving the problem that the ultra-large type pipe plate tailor-welding deformation is difficult to accurately control. Comprising the following steps that (1) a finite element model for tube plate tailor-welding is established, asymmetric double-U-shaped groove design is adopted, the depth of a forward groove is different from that of a reverse groove, the depth of an upper groove is 80 mm-100 mm larger than that of a lower groove, the total number of times of overturning is 10-50, and the number of welding beads in the whole welding process is 10-50; (2) checking the bearing strength; (3) respectively testing the influence of the turnover times and the number of welding beads on the angular deformation; and (4) fitting a relational expression of post-welding residual angular deformation about the number of times of overturning and the number of welding beads according to a data result, so as to form the tailor-welding deformation control process for the ultra-large tube plate. According to the invention, the maximum residual angular deformation after welding is obviously reduced, and the welding quality and the loading capacity of the tube plate are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of controlling the deformation of tube sheet welding, and particularly relates to a method for controlling the deformation of super-large tube sheet welding based on forward and reverse order welding. Background Art

[0002] Large reactors are key equipment in the production process. They have high design parameters and great manufacturing difficulties, and have extremely high requirements for the overall quality and safety of the equipment. As an important part of the reactor, the welding quality of the tube sheet directly affects the overall performance and operation safety of the equipment. However, during the manufacturing process of large reactors, the problem of tube sheet welding deformation has always been a difficult problem that plagues manufacturing enterprises.

[0003] At present, there are mainly three measures for controlling the deformation of tube sheet welding: one is the pre-deformation method, which applies appropriate bending to the tube sheet so that during the welding process, due to the action of thermal expansion and contraction, the deformation direction is opposite to the pre-deformation, thereby reducing the post-weld deformation. However, due to the difficulty in accurately predicting the deformation of super-large tube sheets during welding, the pre-deformation amount cannot accurately match the actual welding deformation, making it difficult to correct and affecting the subsequent assembly accuracy of the tube sheet and the cylinder; the second is the temperature control method, which reduces the heat input by adjusting parameters such as welding current, welding speed, and welding voltage, controls the local temperature field, and avoids deformation caused by local overheating. However, due to the large thickness and long weld length of super-large tube sheets, the heat transfer along the thickness direction is uneven, and it is difficult to stably control the local temperature field, resulting in the accumulation of asymmetric thermal deformation; the third is the fixture fixing method, which designs and uses special fixtures to fix the tube sheet at the welding position according to the structural characteristics of the tube sheet, and uses pressure tools to apply a certain pressure to the welding part to ensure that the tube sheet does not undergo excessive deformation during the welding process. However, it is difficult for the fixture to completely restrain the complex thermal deformation of super-large tube sheets, especially when there is high heat input and asymmetric deformation in the thickness direction, and large residual angular deformation will still occur.

[0004] It can be seen that the welding deformation of the tube sheet is affected by various factors of the welding process, such as the welding sequence, the number of weld beads, etc. How to formulate a scientific and reasonable welding process (the number of flips, the number of weld beads), reduce the deformation of tube sheet welding, and ensure the flatness of the tube sheet after welding is an important problem in the manufacturing process of the tube sheet. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for controlling the deformation of super-large tube sheet welding based on forward and reverse order welding, effectively solving the problem that it is difficult to accurately control the deformation of super-large tube sheet welding.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A method for controlling the deformation of super-large tube sheet butt welding based on forward and reverse order welding. The diameter of the super-large tube sheet is 5000mm - 10000mm, and the thickness is 60mm - 400mm. The material of the super-large tube sheet is the steel plate specified in GB150.2 "Pressure Vessels - Part 2: Materials", including the following steps: S1. Establish a finite element model for tube sheet butt welding: Establish a two-dimensional finite element model of the super-large tube sheet, and adopt an asymmetric double-U groove design. The groove radius is 10mm - 12mm, the groove angle is 3° - 5°, the depths of the forward groove and the reverse groove are different, the depth of the upper groove is 80mm - 100mm longer than the depth of the lower groove, the width of the groove is 24mm - 28mm, the root distance between the upper groove and the lower groove is 10mm - 12mm, the total number of flips is 10 - 50 times, and the number of weld beads in the whole welding process is 10 - 50.

[0008] S2. Check the bearing strength: Find the geometric centroid of the tube sheet and determine the peak position of the bending moment. Use the four-point bending method to calculate the peak bending moment of the tube sheet, check the bearing strength required for the tube sheet to flip, and determine the minimum thickness of the first pass welding.

[0009] S3. Influence of the number of flips on angular deformation: Change the number of weld beads for each forward and reverse alternating filling welding, keep the total number of weld beads the same, change the number of flips of the tube sheet, and compare the influence of the number of flips on the residual angular deformation after welding.

[0010] S4. Influence of the number of weld beads on angular deformation: Change the thickness of each forward and reverse filling welding, keep the number of flips the same, change the number of welding passes, and compare the influence of the number of welding passes on the residual angular deformation after welding.

[0011] S5. Fit the relationship between the residual angular deformation after welding and the number of flips and the number of weld beads according to the data results. Comprehensively consider the influence of the number of flips and the number of weld beads of the tube sheet on the residual angular deformation after welding, form a control process for the deformation of super-large tube sheet butt welding, and optimize the control of the maximum residual angular deformation after welding.

[0012] Further, in step S2, the geometric centroid x of the tube sheet: x = 4r / 3π; the peak position a of the bending moment: a = r - x; the peak bending moment M: The method for verifying the bearing strength is: ≤ yield strength; where b is the diameter of the tube sheet, r is the radius of the tube sheet, G is the gravity of the tube sheet, and h is the minimum thickness of the first pass welding.

[0013] Further, the welding process adopted in steps S3 and S4 is: Preheat treatment is carried out before welding (the preheating temperature is determined according to the material of the steel plate), and first use CO2 gas shielded welding or argon arc welding for backing to ensure full penetration at the root.

[0014] Then, submerged arc automatic welding is used to perform filling welding on the tube sheet alternately from the front and back, controlling the thickness of each layer to avoid slag inclusion and porosity; during the welding process, ensure that the weld bead penetrates completely to avoid lack of fusion. The two sides of the groove on the reverse side of the weld seam need to be continuously preheated and maintain a constant preheating temperature to avoid deformation caused by uneven local cooling rates.

[0015] Finally, perform one layer of capping weld on both the front and back sides to decorate the weld surface and control the reinforcement height ≤ 2 mm.

[0016] After welding is completed, place the tube sheet in a heat treatment furnace for leveling and heat treatment to further eliminate the welding deformation of the tube sheet. Finally, grind the weld seam flush with the base metal. During the welding process, perform UT / MT inspections every 10 weld passes to ensure no defects.

[0017] Furthermore, before welding, uniformly preheat the areas within 200 mm on both sides of the groove on the front and back sides of the tube sheet.

[0018] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0019] (1) By using the method of welding the tube sheet in a two-way sequence from the front and back, the present invention controls the residual angular deformation after welding, significantly reducing the maximum residual angular deformation after welding, reducing the risk of inaccurate joint positions and assembly errors after the tube sheet is welded, thereby improving the welding quality and pressure-bearing capacity of the tube sheet.

[0020] (2) By designing different groove depths on both sides, the present invention enables the heat to transfer towards the thick plate direction during the welding process, and the heat distribution is uniform along the thickness direction, thereby reducing the deformation after welding.

[0021] (3) By reasonably designing the number of welding passes and the number of welding flips, exploring the influence of the welding process on the angular deformation after welding, and forming a deformation control process for the welding of super-large tube sheets, the present invention effectively reduces the residual angular deformation after welding. Description of the Drawings

[0022] Figure 1 It is a schematic diagram of the welding groove structure of Embodiment 1.

[0023] Figure 2 It is the result of the residual angular deformation after welding corresponding to 10 flips in Embodiment 1, where U represents displacement and U2 represents the displacement in the Y direction.

[0024] Figure 3 It is the result of the residual angular deformation after welding corresponding to 20 flips in Embodiment 1, where U represents displacement and U2 represents the displacement in the Y direction.

[0025] Figure 4It is the post-weld residual angular deformation result corresponding to 30 weld beads in Example 1, where U represents displacement and U2 represents the displacement in the Y direction.

[0026] Figure 5 It is the post-weld residual angular deformation result corresponding to 20 weld beads in Example 1, where U represents displacement and U2 represents the displacement in the Y direction.

[0027] Figure 6 It is the two-dimensional cloud diagram of the post-weld residual angular deformation of different weld bead numbers and flipping times in Example 1.

[0028] Figure 7 It is the post-weld residual angular deformation under the optimal welding process of Example 1, where U represents displacement and U2 represents the displacement in the Y direction.

[0029] Figure 8 It is the schematic diagram of the welding groove structure of Example 2.

[0030] Figure 9 It is the two-dimensional cloud diagram of the post-weld residual angular deformation of different weld bead numbers and flipping times in Example 2.

[0031] Figure 10 It is the post-weld residual angular deformation result of Comparative Example 1, where U represents displacement and U2 represents the displacement in the Y direction. Specific implementation method

[0032] Example 1: A method for controlling the deformation of super-large tube-sheet butt welding based on forward and reverse sequence welding. In this example, the tube-sheet material is SA508 steel plate, the tube-sheet diameter is 8754 mm, the tube-sheet thickness is 290 mm, and the process steps are as follows.

[0033] S1. Establish a finite element model of tube-sheet butt welding: Establish a two-dimensional finite element model of a super-large tube-sheet, and adopt an asymmetric double-U groove design: the depth of the forward groove is 180 mm, the groove angle is 3°, the maximum groove width is 28 mm, the groove radius is 10 mm; the depth of the reverse groove is 100 mm, the groove angle is 3°, the maximum groove width is 24 mm, the groove radius is 10 mm; the root distance between the upper groove and the lower groove is 10 mm. The structure is as Figure 1 shown.

[0034] S2. Check the bearing strength: The diameter b of the tube-sheet is 8.754 m, the radius r of the tube-sheet is 4.377 m, the weight of the tube-sheet is 68473 kg, the gravity G of the tube-sheet is 671037 N, the yield strength of the material is 485 MPa, and the four-point bending method is used for calculation.

[0035] The geometric centroid x of the tube-sheet: x = 4r / 3π; the peak position a of the bending moment: a = r - x = 2.52 m; the peak bending moment M:

[0036] The bearing strength verification method is as follows: ≤yield strength; Solving gives that the thickness h of the minimum welding surface of the first weld is 35 mm.

[0037] S3. Influence of the number of flips on angular distortion: Change the number of weld beads filled alternately in each positive and negative cycle, keep the total number of weld beads the same, change the number of flips of the tube sheet, and compare the influence of the number of flips on the residual angular distortion after welding.

[0038] Before welding, within a range of 200 mm on both sides of the groove on the front and back of the steel plate, use gas to uniformly preheat to reduce welding residual stress and welding deformation. The preheating temperature ≥200 °C, the preheating time is 40 - 60 min to make the preheating uniform.

[0039] (1) First, use CO2 gas shielded welding to weld 6 mm of the backing layer on both the front and back to ensure full penetration at the root. (2) Then, use submerged arc automatic welding for alternate filling welding on both the front and back. Weld 3 passes in sequence on the front, each pass welding 5.8 mm thick. Flip the tube sheet, and weld 2 passes in sequence on the back, each pass welding 4.7 mm thick. Flip 20 times in sequence, and the total number of welding passes is 50. (3) Finally, weld 1 cover pass on both the front and back, with a thickness of 5 mm, to finish the surface of the weld and control the reinforcement ≤2 mm to complete the welding of the entire welded joint.

[0040] The welding process parameters of submerged arc automatic welding are: welding current 450 A - 600 A, arc voltage 32 V - 36 V, welding speed 50 - 55 cm / min, interpass temperature 150 - 260 °C.

[0041] After welding, perform heat treatment. The heat treatment process is: the furnace inlet temperature ≤350 °C, the heating rate 50 °C / h - 60 °C / h, the heat treatment temperature 620 °C ± 20 °C, hold for 4 hours, the cooling rate 50 °C - 60 °C / h, and when the furnace temperature ≤200 °C, take it out of the furnace and air cool. Finally, grind the weld flush with the base metal, and perform 100% ultrasonic testing, with Class I qualification.

[0042] Keep the total number of welding passes unchanged, reduce the number of flips, and increase the number of welding passes in each layer during welding. (1) First, use CO2 gas shielded welding to weld 6 mm of the backing layer on both the front and back to ensure full penetration at the root. (2) Then, use submerged arc automatic welding for alternate filling welding on both the front and back. Weld 6 passes in sequence on the front, each pass welding 5.8 mm thick. Flip the tube sheet, and weld 4 passes in sequence on the back, each pass welding 4.7 mm thick. Flip 10 times in sequence, and the total number of welding passes is 50. (3) Finally, weld 1 cover pass on both the front and back, with a thickness of 5 mm, to finish the surface of the weld and control the reinforcement ≤2 mm to complete the welding of the entire welded joint.

[0043] The maximum post-weld residual angular deformation after 10 flips is 53.6 mm, and the maximum post-weld residual angular deformation after 20 flips is 39.3 mm; the maximum residual angular deformation is reduced by 26.6%, as Figure 2 and Figure 3 shown. Therefore, increasing the number of flips can reduce the maximum post-weld residual angular deformation.

[0044] S4. Influence of the number of weld passes on angular deformation: Change the thickness of each forward and reverse filling weld, keep the number of flips the same, change the number of welding passes, and compare the influence of the number of welding passes on the post-weld residual angular deformation.

[0045] Before welding, within a range of 200 mm on both sides of the groove on the front and back of the steel plate, uniform preheating treatment is carried out with gas. (1) First, use CO2 gas shielded welding to weld a 6-mm backing layer on both the front and back to ensure full penetration at the root. (2) Then, use submerged arc automatic welding for alternating filling welding on both the front and back. Weld 2 passes in sequence in the forward direction, with each welding pass being 8.7 mm thick. Flip the tube sheet, and weld 1 pass in sequence in the reverse direction, with each welding pass being 9.4 mm thick; flip 20 times in sequence, and the total number of welding passes is 30.

[0046] Keep the number of flips unchanged and change the number of weld passes. (1) First, use CO2 gas shielded welding to weld a 6-mm backing layer on both the front and back to ensure full penetration at the root. (2) Then, use submerged arc automatic welding for alternating filling welding on both the front and back. Weld 1 pass in sequence in the forward direction, with each welding pass being 17.4 mm thick. Flip the tube sheet, and weld 1 pass in sequence in the reverse direction, with each welding pass being 9.4 mm thick; flip 20 times in sequence, and the total number of welding passes is 20.

[0047] When the number of weld passes is 30, the maximum post-weld residual angular deformation is 22.09 mm; when the number of weld passes is 20, the maximum post-weld residual angular deformation is 12.76 mm, and the maximum residual angular deformation is reduced by 42.2%, as Figure 4 and Figure 5 shown. Reducing the number of weld passes can reduce the maximum post-weld residual angular deformation.

[0048] S5. Tube sheet butt welding deformation control process: According to the above finite element simulation method for tube sheet butt welding, adjust the parameters of the number of flips and the number of weld passes for multiple simulations, and perform data fitting based on the simulation results to obtain the relationship formula of each factor with respect to angular deformation.

[0049] The relationship formula of the maximum post-weld residual angular deformation with respect to the number of flips and the number of weld passes is: d = 13.8 + 0.9n - 0.91N, where d is the maximum post-weld angular deformation, with the unit of mm; N is the number of flips, and n is the number of weld passes.

[0050] Considering the influence laws of the number of flips and the number of weld beads on angular distortion comprehensively, the post-weld residual angular distortion for each number of flips and the number of weld beads is represented in a two-dimensional contour map, as Figure 6 shown.

[0051] It is obtained through Figure 6 that: as the number of weld beads decreases, the maximum residual angular distortion decreases; as the number of flips increases, the maximum residual angular distortion decreases. For the two factors of the number of weld beads and the number of flips, they restrict and influence each other. At the same number of flips, the fewer the number of weld beads, the smaller the maximum residual angular distortion, and the number of weld beads is restricted by the number of flips. As the number of flips increases, the number of weld beads will increase. The optimal control process for large-scale tube-sheet butt welding is: select a smaller number of weld beads when choosing a moderate number of flips. In this embodiment, the optimal welding control process for residual angular distortion is determined as: 30 flips, 30 weld beads, and the maximum post-weld residual angular distortion is 5.82 mm, as Figure 7 shown.

[0052] Example 2: A deformation control method for super-large tube-sheet butt welding based on forward and reverse sequence welding. The tube-sheet material in this embodiment is SA508 steel plate, the tube-sheet diameter is 5100 mm, and the tube-sheet thickness is 200 mm. The difference between the process steps and those of Example 1 lies in

[0053] In step S1, an asymmetric double-U groove design is adopted: the depth of the forward groove is 110 mm, the groove angle is 3°, the maximum groove width is 25 mm, and the groove radius is 10 mm; the depth of the reverse groove is 80 mm, the groove angle is 3°, the maximum groove width is 22 mm, and the groove radius is 10 mm; the root distance between the upper groove and the lower groove is 10 mm. The structure is as Figure 8 shown.

[0054] In steps S3 and S4, (1) First, use CO2 gas shielded welding to weld a 5-mm backing layer on both the front and back sides to ensure full penetration at the root. (2) Then, use automatic submerged arc welding for alternating filling welding on both the front and back sides. Weld 2 passes in the forward direction successively, with each welding pass having a thickness of 10.5 mm. Flip the tube-sheet, weld 2 passes in the reverse direction successively, with each welding pass having a thickness of 7.5 mm, and flip 10 times successively. The total number of welding passes is 20. (3) Finally, perform 1 cover pass welding on both the front and back sides, with a thickness of 4 mm, to modify the weld surface and control the reinforcement height ≤ 2 mm to complete the welding of the entire welded joint. The post-weld residual angular distortion is 21.6 mm.

[0055] The welding process parameters for automatic submerged arc welding are as follows: welding current is 550A - 600A, arc voltage is 36V - 38V, welding speed is 55 - 58 cm / min, and interlayer temperature ≤ 200°C. After welding, heat treatment is carried out. The heat treatment process is as follows: furnace inlet temperature ≤ 350°C, heating rate is 50°C / h - 60°C / h, heat treatment temperature is 620°C ± 20°C, holding time is 4 hours, cooling rate is 50°C - 60°C / h, and when the furnace temperature ≤ 200°C, it is taken out of the furnace for air cooling. Finally, the weld seam is ground flush with the base metal, and 100% ultrasonic testing is carried out, with grade I being qualified.

[0056] Multiple simulations were carried out by changing the number of flips and the number of weld beads in the fill welding, and the residual angular deformation corresponding to the number of flips and the number of weld beads was obtained as Figure 9 shown.

[0057] The relationship between the maximum residual angular deformation after welding and the number of flips and the number of weld beads is: d = 2.56 + 1.46n - 1.1N.

[0058] From Figure 9 it can be seen that the residual angular deformation after welding is jointly affected by the number of flips and the number of weld beads, and the two restrict and balance each other. Considering the effects of the number of flips and the number of weld beads on angular deformation comprehensively, the optimal welding control process for residual angular deformation is: 16 flips, 16 weld beads, and the maximum residual angular deformation after welding is 3.2 mm.

[0059] Comparative example 1: The tube sheet material in this comparative example is SA508 steel plate, the diameter of the tube sheet is 8754 mm, and the thickness of the tube sheet is 290 mm.

[0060] This comparative example also adopts an asymmetric double U-groove design: the depth of the forward groove is 180 mm, the groove angle is 3°, the maximum groove width is 28 mm, and the groove radius is 10 mm; the depth of the reverse groove is 100 mm, the groove angle is 3°, the maximum groove width is 24 mm, and the groove radius is 10 mm; the root distance between the upper groove and the lower groove is 10 mm. The structure is as Figure 1 shown.

[0061] The difference between this comparative example and Example 1 is that in this comparative example, the deformation control method of welding in two-way order (forward and reverse) is not adopted during the welding of the super-large tube sheet. Therefore, there is no need to consider the problem of the minimum welding thickness of the first weld.

[0062] The tube sheet welding process in this comparative example is as follows: (1) Use automatic submerged arc welding in the forward direction to complete the welding of the forward groove in 30 weld beads in sequence, with the welding thickness of each bead being 6 mm.

[0063] (2) After the forward welding is completed, flip the tube sheet and carry out reverse welding for 20 times, with each welding thickness of 5 mm, and finally complete the welding of the entire welded joint.

[0064] After welding, heat treatment is carried out. The heat treatment process is as follows: the furnace inlet temperature ≤ 350 °C, the heating rate is 50 °C / h to 60 °C / h, the heat treatment temperature is 620 °C ± 20 °C, keep warm for 4 hours, the cooling rate is 50 °C to 60 °C / h, and when the furnace temperature ≤ 200 °C, take out and air-cool.

[0065] Finally, grind the weld seam flush with the base metal, conduct 100% ultrasonic testing, and the first grade is qualified. The maximum residual angular deformation after welding in this comparative example is 72.16 mm, as Figure 10 shown.

[0066] The maximum residual angular deformation after welding in Comparative Example 1 is larger than the results of any welding process in Example 1. By comparing Figure 10 and Figures 2 - 5 it is found that the maximum residual angular deformation after welding is reduced by up to 87%. By Figures 2 - 7 and Figure 10 it is concluded that during the welding of super-large tube sheets, the method of welding the tube sheet in a forward and reverse order can control the residual angular deformation after welding, significantly reducing the maximum residual angular deformation after welding, reducing the risk of inaccurate joint positions and assembly errors after the tube sheet welding, thereby improving the welding quality and pressure-bearing capacity of the tube sheet.

[0067] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by those skilled in the art within the scope of the essence of the present invention should also fall within the protection scope of the present invention.

Claims

1. A deformation control method for super-large tube sheet tailoring based on forward and reverse order welding, wherein the diameter of the super-large tube sheet is 5000mm-10000mm and the thickness is 60mm-400mm, characterized in that: The following steps are involved: S1. Establish the finite element model of tube-sheet welding; A two-dimensional finite element model of a super-large tube sheet was established, and an asymmetric double U-shaped groove design was adopted: the groove radius was 10mm-12mm, the groove angle was 3°-5°, the depth of the positive groove was different from that of the reverse groove, the depth of the upper groove was 80mm-100mm longer than that of the lower groove, the width of the groove was 24mm-28mm, the root distance between the upper groove and the lower groove was 10mm-12mm, the total number of flips was 10-50 times, and the number of welds in the entire welding process was 10-50; S2. Bearing strength verification; Calculate the geometric center of gravity of the tube sheet and determine the peak position of the bending moment. Use the four-point bending method to calculate the peak bending moment of the tube sheet, check the bearing strength required for the tube sheet to flip, and determine the minimum thickness of the first weld. S3, the effect of flipping times on angular deformation; Change the number of welds in each positive and negative alternating fill welding, keep the total number of welds the same, change the number of tube sheet flips, and compare the effect of the number of flips on the residual angle deformation after welding; S4. Effect of number of weld passes on angular deformation; Change the thickness of each forward and reverse fill welding, keep the same number of flips, change the welding pass, and compare the effect of the welding pass on the residual angle deformation after welding; S5. According to the data results, the relationship between the number of flipping times and the number of weld passes after welding is fitted, and the influence of the number of flipping times and the number of weld passes of the tube sheet on the residual angle deformation after welding is comprehensively considered to form a deformation control process for super-large tube sheet welding.

2. The deformation control method for super-large tube sheet tailoring based on forward and reverse order welding according to claim 1 is characterized in that: In step S2, the geometric center of gravity x of the tube sheet: x = 4r / 3π; Peak position of bending moment a: a = rx; Peak bending moment M: The bearing strength verification method is: Where b is the tube sheet diameter, r is the tube sheet radius, G is the tube sheet gravity, and h is the minimum thickness of the first weld.

3. The deformation control method for super-large tube sheet tailoring based on forward and reverse order welding according to claim 2 is characterized in that: The welding process used in step S3 and step S4 is: Preheating is performed before welding, and CO2 gas shielded welding or argon arc welding is used to prime the weld to ensure that the root is fully melted; Then, the tube sheet is filled and welded alternately in the positive and negative directions by automatic submerged arc welding to control the thickness of each layer and avoid slag inclusion and pores. During the welding process, the weld is ensured to be fully melted to avoid incomplete fusion. The groove on the reverse side of the weld needs to be preheated continuously and a constant preheating temperature is maintained to avoid deformation caused by uneven local cooling rate. Finally, perform a cover weld on both the front and back sides to modify the weld surface and control the excess height to ≤2mm; After welding is completed, the tube sheet is placed in a heat treatment furnace for leveling and heat treatment, and finally the weld is ground to be flush with the parent material. During the welding process, UT / MT testing is performed every 10 passes.

4. The deformation control method for super-large tube sheet tailoring based on forward and reverse order welding according to claim 3 is characterized in that: Before welding, evenly preheat the area within 200mm on both sides of the groove on the front and back sides of the tube sheet.

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