Container ship thick plate welding method
By determining the steel grade and welding parameters according to the location of the thick plate and adopting a specific welding method and sequence, the problems of low efficiency and poor quality in thick plate welding on large container ships were solved, and efficient and reliable welding results were achieved.
Patent Information
- Application Number
- CN202510830183.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-20
- Publication Date
- 2025-09-09
AI Technical Summary
The welding efficiency of thick plates in the torsion box area of large container ships is low and the quality is poor, which easily damages the steel plates and affects the quality and cycle of ship construction.
Determine the steel grade according to the location of the thick plate, select the appropriate welding method, welding material model and welding material grade, adopt a specific groove form and welding sequence, control the welding current, voltage and welding sequence, and use submerged arc welding and CO2 gas shielded welding for welding.
It improves the reliability and quality of thick plate welding on container ships, reduces welding difficulty, improves welding efficiency, and provides technical support for the efficient construction of container ships.
Smart Images
Figure CN120606143A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of welding, and in particular to a method for welding thick plates of container ships. Background Art
[0002] Container ships are one of the main types of ships in global shipping. With the continuous innovation of my country's shipbuilding technology and shipbuilding processes, my country has a significant position in the container ship construction market. Currently, the largest container has reached 24,000 TEUs. The torsion box area of a container ship is a key component in its structural design, primarily used to enhance the ship's torsional rigidity and lateral strength to cope with the torsional stresses generated by container loading and wave loads. The plate thickness of the torsion box area of large container ships is typically over 80mm, and the plate is typically made of high-strength crack-arresting steel. Existing technology for welding thick plates in the torsion box area of large container ships is prone to damage to the steel plates, and the welding efficiency is low, resulting in poor welding quality, which affects the quality and cycle time of ship construction. Summary of the Invention
[0003] In response to the defects in the existing technology, the present application provides a container ship thick plate welding method and ship to solve the technical problems of low efficiency and poor quality of thick plate welding in the torsion box area of large container ships in the existing technology, and easy counting of steel plates.
[0004] In order to achieve the purpose of the above invention, the technical solution provided by the present invention is as follows:
[0005] A method for welding thick plates for container ships, wherein the thickness of the thick plates is at least 80 mm, the welding method comprising:
[0006] S1. Determine the steel grade of the thick plate: Determine the steel grade of the thick plate according to its location
[0007] S2. Determine the welding mode, welding material type and welding material grade: Determine the welding mode, welding material type and welding material grade based on the thick plate steel determined in S1;
[0008] S3. Determine the weld groove form based on the welding style: When the welding style is plate welding, the groove of the plate weld adopts an X-shaped double-sided asymmetric groove, with a front groove angle of 50-60°, a back groove angle of 70-80°, a root of 6mm, and a root gap of 0-1mm. The welding method is submerged arc welding. When the welding style is fillet welding, the groove of the fillet weld adopts a double-sided 45° K-shaped symmetrical groove with a root of 1 / 3t-1 / 2t, where t is the thickness of the thick plate, and the fillet weld is deep penetration welding.
[0009] S4. Prepare before welding: clean the area around the groove to ensure there is no dirt within 20mm of the two edges of the groove, preheat the thick plate, and perform tack welding on the thick plate;
[0010] S5. Formal welding of thick plates: When welding the panels, weld the front weld first, then turn the panels over and clean the roots with carbon planers. When cleaning the roots with carbon planers, make the bottom opening of the weld groove as large as possible, and weld the back of the weld after polishing. When using submerged arc automatic welding, install arc starting and arc ending plates between the starting and ending ends of the weld. The thickness difference between the arc starting and arc ending plates of the panel weld and the weldment is plus or minus 2mm. The size of the arc starting and arc ending plates is 150×150mm. The arc starting length is not less than 80mm, and the arc extinction length is not less than 50mm. When using multi-pass and multi-layer welding, the welding should maintain continuity, the interlayer temperature should be above the preheating temperature, the welding slag and spatter should be removed after each weld, and the joints of each weld should be staggered to At least 30 to 50 mm; when welding longitudinal bones, heat while welding, and an even number of welders weld on both sides of the longitudinal bones at the same time, and use the step-by-step retreat welding method or the center welding method for welding; when the component and the plate seam intersect, if there are both butt joints and fillet welds, weld the butt welds first, then weld the fillet welds, and weld the vertical fillet welds first and then the flat fillet welds; when the weld height of the plate affects the tight installation of the component, grind the weld height, and the grinding length should not be less than the thickness of the component plate, or open a through welding hole; fill the arc crater at the end of the weld, and the through welding hole or the leak-proof hole has a good wrap angle; if the wind speed is greater than 2 meters per second during outdoor welding, windproof measures need to be taken around the weld, and do not weld in the open air when it rains.
[0011] In one embodiment, the steel grade of the thick plates at the hatch coaming in S1 is EH47 steel, the steel grade of the thick plates at the main deck is EH40 steel, the steel grade of the thick plates at the shell plating is EH40, DH32 or AH32 steel, the steel grade of the thick plates at the longitudinal bulkheads is EH40, DH32 or AH32 steel, and the steel grade of the thick plates at the longitudinals is AH40, AH32 or HP300*12AH type bulb flat steel.
[0012] In one embodiment, if the steel grades of the thick plates to be welded in S2 are EH47 and EH40 respectively, the welding method is CO2 gas shielded semi-automatic welding, CO2 automatic fillet welder or single-wire submerged arc automatic welding; if the steel grades of the thick plates to be welded are EH40 and AH40 respectively, the welding method is CO2 gas shielded semi-automatic welding or CO2 automatic fillet welder; if the steel grades of the thick plates to be welded are EH47 and EH40 respectively, the welding method is CO2 gas shielded semi-automatic welding, CO2 automatic fillet welder or single-wire submerged arc automatic welding; if the steel grades of the thick plates to be welded are EH47, EH40 and EH36 and below respectively, the welding method is CO2 gas shielded semi-automatic welding, CO2 automatic fillet welder or single-wire submerged arc automatic welding; if the steel grade of the thick plates to be welded is EH36 and below, the welding method is CO2 gas shielded semi-automatic welding, CO2 automatic fillet welder or single-wire submerged arc automatic welding.
[0013] In one embodiment, the length of the tack weld in S4 is not less than 50 mm, the spacing between the tack welds is 300-500 mm, and the welding materials used for the tack welds are of the same grade as those used for the formal welding. If there are welding defects in the tack welds, the tack welds with welding defects need to be removed and re-tack welded. All EH47 steel plates need to be preheated to above 100°C.
[0014] In one embodiment, in said S5, during the carbon dioxide gas shielded welding process, a welding wire with a diameter of 1.2 mm is selected; during the submerged arc welding process, a welding wire with a diameter of 4.0 mm is selected.
[0015] In one embodiment, in said S5, during the bottom welding: in the process of flat welding using submerged arc welding, the welding current is 600-700A; in the process of vertical welding using carbon dioxide gas shielded welding, the welding current is 230-260A; in the process of horizontal welding using carbon dioxide gas shielded welding, the welding current is 180-210A; in the process of overhead welding using carbon dioxide gas shielded welding, the welding current is 210-240A;
[0016] When welding the filler pass: in the process of submerged arc welding, the welding current is 610-710A; in the process of vertical welding with carbon dioxide gas shielded welding, the welding current is 235-265A; in the process of horizontal welding with carbon dioxide gas shielded welding, the welding current is 180-210A; in the process of overhead welding with carbon dioxide gas shielded welding, the welding current is 210-240A;
[0017] When welding the cap weld: in the process of submerged arc welding, the welding current is 600-690A; in the process of vertical welding with carbon dioxide gas shielded welding, the welding current is 210-240A; in the process of horizontal welding with carbon dioxide gas shielded welding, the welding current is 175-205A; in the process of overhead welding with carbon dioxide gas shielded welding, the welding current is 205-235A.
[0018] In one embodiment, in S5, the voltage during carbon dioxide gas shielded welding is controlled at 25-36V, when carbon dioxide gas shielded welding uses multi-layer welds, the swing width of each weld is controlled within 10 times the wire diameter, and the welding speed is controlled between 440-550mm / min; when submerged arc welding uses multi-layer welds, the welding speed is controlled between 450-550mm / min; when there are multi-layer welds, the thickness of each weld layer is controlled between 3-5mm; and the interlayer temperature is below 250°C during the entire welding process.
[0019] In one embodiment, S5 also includes the principle of welding sequence: longer butt welds should generally be welded from the middle to both ends; when butt welds and fillet welds exist in a component at the same time, the butt welds should be welded first and then the fillet welds; welds that do not form rigid constraints on the shrinkage of other welds should be welded first, and then the constraint welds should be welded, the main components should be welded first, and then the secondary components; when welding each weld, one end should be kept with room for free shrinkage; because the lateral shrinkage of the weld is greater than the longitudinal shrinkage, when welding the plate rows, the end joints should be welded first, then the side joints, and finally the flush transverse joints; when welding the frame and the plate seam, the plate seam should be welded first, then the butt welds between the frames, and finally the corner joints between the frame and the plate; the welding of the segments should be symmetrical by multiple people, starting from the center of the segment and expanding to the surrounding areas; when welding the large closing seam of the total segment, a symmetrical welding sequence should be adopted to make both sides of the neutral axis shrink evenly; flat fillet welds are not allowed to be excessively biased toward the plate.
[0020] Compared with the prior art, this application has at least the following beneficial effects:
[0021] This container ship thick plate welding method determines the steel grade of the thick plate based on its location, the welding method, welding material type, and welding material grade based on the steel grade, and the weld groove form based on the welding style. Furthermore, the welding current, voltage, and welding sequence are set during the actual welding of the thick plate. This method effectively prevents damage to the steel plate ruler during the container ship thick plate welding process, improves the welding reliability and quality of container ships, effectively reduces welding difficulty, and improves welding efficiency. This provides technical support for the efficient construction of container ships. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 This is a schematic diagram of the structure of the welding groove of the thick and thick plate in the embodiment of the present application;
[0023] Figure 2 This is a schematic diagram of the structure of the welding groove of the medium and thick plate fillet weld in the embodiment of the present application. DETAILED DESCRIPTION
[0024] To make the objectives, technical solutions, and advantages of the present invention more clearly apparent, the present invention is described below using specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely illustrative and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present invention.
[0025] The terms used in this disclosure are for the purpose of describing specific embodiments only and are not intended to limit the disclosure. As used in this disclosure and the appended claims, the singular forms "a," "an," "the," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.
[0026] It should be understood that although the terms first, second, third, etc. may be used in this disclosure to describe various information, such information should not be limited to these terms and should not be understood to indicate or imply relative importance. These terms are only used to distinguish information of the same type from each other. For example, first information may also be referred to as second information, and similarly, second information may also be referred to as first information without departing from the scope of this disclosure. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining."
[0027] In the description of the present invention, unless otherwise specified and limited, it should be noted that the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a mechanical connection or the internal communication between two components. It can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances.
[0028] In order to better understand the technical solution of the present invention, the present invention is described in detail below in conjunction with specific implementation methods.
[0029] A method for welding thick plates for container ships, wherein the thickness of the thick plates is at least 80 mm, the welding method comprising the following steps:
[0030] S1. Determine the steel grade of the thick plate: Determine the steel grade of the thick plate according to its location.
[0031] In this embodiment, the thick plates at the hatch coamings are made of EH47 steel, the thick plates at the main decks are made of EH40 steel, the thick plates at the shell plating are made of EH40, DH32 or AH32 steel, the thick plates at the longitudinal bulkheads are made of EH40, DH32 or AH32 steel, and the thick plates at the longitudinals are made of AH40, AH32 or HP300*12AH bulb flat steel.
[0032] S2. Determine the welding mode, welding material type and welding material grade: As shown in Table 1, determine the welding mode, welding material type and welding material grade based on the thick plate steel determined in S1.
[0033] Table 1:
[0034]
[0035] If the steel grades of the thick plates to be welded are EH47 and EH40 respectively, the welding method is CO2 gas shielded semi-automatic welding, CO2 automatic fillet welding machine or single-wire submerged arc automatic welding; if the steel grades of the thick plates to be welded are EH40 and AH40 respectively, the welding method is CO2 gas shielded semi-automatic welding or CO2 automatic fillet welding machine; if the steel grades of the thick plates to be welded are EH47 and EH40 respectively, the welding method is CO2 gas shielded semi-automatic welding, CO2 automatic fillet welding machine or single-wire submerged arc automatic welding; if the steel grades of the thick plates to be welded are EH47, EH40 and EH36 and below respectively, the welding method is CO2 gas shielded semi-automatic welding, CO2 automatic fillet welding machine or single-wire submerged arc automatic welding; if the steel grade of the thick plates to be welded is EH36 and below, the welding method is CO2 gas shielded semi-automatic welding, CO2 automatic fillet welding machine or single-wire submerged arc automatic welding.
[0036] S3. Determine the weld groove form according to the welding style: When the welding style is panel welding, the groove of the panel weld is as follows: Figure 1 The X-shaped double-sided asymmetric form is shown, with a front groove angle of 50-60° and a back groove angle of 70-80°. The root is 6mm and the root gap is 0-1mm. The welding method is submerged arc welding to prevent large deformation of the single-sided groove and reduce the amount of filling in the welding. When the welding style is fillet welding, the groove of the fillet weld is as follows: Figure 2 The figure shows a double-sided 45° K-type symmetrical groove with a root of 1 / 3t-1 / 2t, t is the thickness of the thick plate, the fillet welding is deep penetration welding, and the fillet welding areas are concentrated in the hatch coaming, longitudinal bulkhead and shell plate areas, during the welding stages of the small assembly, medium assembly and large assembly stages.
[0037] S4. Prepare before welding: clean the area around the groove to ensure that there is no rust, garbage or other dirt within 20mm of the two edges of the groove, preheat the thick plate, and perform positioning welding on the thick plate.
[0038] In this embodiment, the tack weld length is no less than 50 mm, and the spacing between tack welds is 300-500 mm. The welding consumables used for tack welds are of the same grade as those used for the main weld. If a tack weld contains a defect, the defective tack weld must be removed and re-tack welded. All EH47 steel plates must be preheated to above 100°C to ensure weld quality.
[0039] S5. Formal welding of thick plates: When welding the panels, weld the front weld first, then turn the panels over and clean the roots with carbon planers. When cleaning the roots with carbon planers, make the bottom opening of the weld groove as large as possible, and weld the reverse side of the weld after polishing it. When using submerged arc automatic welding, install arc starting and arc ending plates between the starting and ending ends (i.e., the free ends). The thickness difference between the arc starting and arc ending plates of the panel weld and the weldment is plus or minus 2mm. The size of the arc starting and arc ending plates is 150×150mm. The arc starting length is not less than 80mm, and the arc extinction length is not less than 50mm. When using multi-pass and multi-layer welding, the welding should maintain continuity, the interlayer temperature should be above the preheating temperature, the welding slag and spatter should be removed after each weld, and the joints of each weld should be mutually Stagger at least 30 to 50 mm; when welding longitudinal bones, heat while welding, and an even number of welders weld on both sides of the longitudinal bones at the same time, and use the step-by-step back welding method or center welding for welding; when the component and the plate seam intersect, if there are both butt welds and fillet welds, weld the butt welds first, then weld the fillet welds, and weld the vertical fillet welds first and then the flat fillet welds; when the weld height of the plate affects the tight installation of the component, grind the weld height, and the grinding length should not be less than the component plate thickness, or open a through welding hole; fill the arc crater at the end of the weld, and the through welding hole or leak-proof hole has a good wrap angle; if the wind speed is greater than 2 meters per second during outdoor welding, windproof measures need to be taken around the weld, and do not weld in the open air when it rains.
[0040] The choice of welding wire diameter significantly impacts both welding quality and production efficiency, often creating a conflict between these two. Excessive wire diameter and heat input can affect the weld and the internal structure of the base material. To improve production efficiency, a wire with a larger diameter should be selected. However, excessively thick wire can result in incomplete penetration or poor weld formation. In this embodiment, in S5, a 1.2 mm diameter wire is selected for CO2 gas shielded welding, citing its superior performance, more even heat input, and higher production efficiency. During submerged arc welding, a 4.0 mm diameter wire is selected to ensure the performance of the weld and heat-affected zone.
[0041] In this embodiment, the formal welding of thick plates also includes the selection of welding parameters as shown in Table 2: the welding current has a great influence on the quality and efficiency of welding. The number of layers of ultra-thick plates welded in the torsion box is very large. In order to ensure the quality of the back weld, during the bottom welding: in the process of flat welding using submerged arc welding, the welding current is 600-700A; in the process of vertical welding using carbon dioxide gas shielded welding, the welding current is 230-260A; in the process of horizontal welding using carbon dioxide gas shielded welding, the welding current is 180-210A; in the process of overhead welding using carbon dioxide gas shielded welding, the welding current is 210-240A.
[0042] In order to improve efficiency and ensure good fusion, when welding the filler weld: in the process of submerged arc welding, the welding current is 610-710A; in the process of vertical welding with carbon dioxide gas shielded welding, the welding current is 235-265A; in the process of horizontal welding with carbon dioxide gas shielded welding, the welding current is 180-210A; in the process of overhead welding with carbon dioxide gas shielded welding, the welding current is 210-240A.
[0043] In order to prevent undercuts and ensure beautiful weld formation, when welding the cover weld: in the process of submerged arc welding, the welding current is 600-690A; in the process of vertical welding using carbon dioxide gas shielded welding, the welding current is 210-240A; in the process of horizontal welding using carbon dioxide gas shielded welding, the welding current is 175-205A; in the process of overhead welding using carbon dioxide gas shielded welding, the welding current is 205-235A.
[0044] During CO2 gas shielded welding, excessive voltage or excessive arc duration can lead to unstable arc combustion, increased metal spatter, and defects such as porosity. In this embodiment, the voltage during CO2 gas shielded welding is controlled between 25-36V. Welding speed refers to the speed at which the welding wire moves along the welding direction during welding, i.e., the length of the weld completed per unit time. Because the base metal has a strong tendency to harden, welding speed directly determines the amount of heat input. When using multiple passes in CO2 gas shielded welding, the oscillation width of each weld should be controlled within 10 times the wire diameter, and the welding speed should be controlled between 440-550 mm / min. When using multiple passes in submerged arc welding, the welding speed should be controlled between 450-550 mm / min. The number and thickness of weld layers: For high-strength steel, the thickness of each weld layer affects the microstructure and mechanical properties. When welding thick plates, a small number of weld layers and excessive weld thickness can lead to decreased plasticity and toughness of the weld joint due to grain coarsening. If steel of the same thickness is welded using multiple passes or multiple layers, the weld joint microstructure becomes significantly finer and the heat-affected zone narrower. The previous weld preheats the subsequent weld, while the subsequent weld heat treats the previous weld, resulting in relatively good joint plasticity and toughness. To ensure the structural properties of the joint, the thickness of each weld layer should be controlled between 3-5mm when multiple welds are used. The interpass temperature should not be too high, as this will burn away beneficial metals in the weld and reduce its structural properties. The interpass temperature should be kept below 250°C throughout the welding process.
[0045] Table 2:
[0046]
[0047]
[0048] S5 also includes the welding sequence principle: longer butt joints should generally be welded from the middle to both ends; when butt welds and fillet welds exist in a component at the same time, the butt welds should be welded first and then the fillet welds; welds that will not form rigid constraints on the shrinkage of other welds should be welded first, and then the constraint welds should be welded. Weld the main components first, then the secondary components; keep one end of each weld to have room for free contraction when welding; because the lateral contraction of the weld is greater than the longitudinal contraction, weld the end joint first, then the side joint, and finally the flush transverse joint when welding the plate row; when welding the skeleton and the plate seam, the plate seam should be welded first, then the butt joint between the skeletons, and finally the corner joint between the skeleton and the plate; the welding of the segments should be done symmetrically by multiple people, starting from the center of the segment and expanding to the surrounding areas; when welding the large closed joints of the total segment, a symmetrical welding sequence should be adopted to make both sides of the neutral axis shrink evenly; vigorously promote high-efficiency welding, reduce welding stress and deformation such as CO2 gas shielded welding, vertical automatic welding, submerged arc automatic welding, argon arc welding, etc.; control the welding line energy, and the fillet welds are strictly carried out according to the specification table, and exceeding the standard is not allowed. High current, thick diameter electrodes and arc pulling and arc jumping welding methods are prohibited, and flat fillet welds are not allowed to be excessively biased towards the plate.
[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solutions of the present invention. They should all be included in the scope of the technical solutions for which protection is sought in the present invention.
Claims
1. A container ship thick plate welding method, characterized in that: The thickness of the thick plate is at least 80 mm, and the welding method comprises: S1. Determine the steel grade of the thick plate: Determine the steel grade of the thick plate according to its location S2. Determine the welding mode, welding material type and welding material grade: Determine the welding mode, welding material type and welding material grade based on the thick plate steel determined in S1; S3. Determine the weld groove form based on the welding style: When the welding style is plate welding, the groove of the plate weld adopts an X-shaped double-sided asymmetric groove, with a front groove angle of 50-60°, a back groove angle of 70-80°, a root of 6mm, and a root gap of 0-1mm. The welding method is submerged arc welding. When the welding style is fillet welding, the groove of the fillet weld adopts a double-sided 45° K-shaped symmetrical groove with a root of 1 / 3t-1 / 2t, where t is the thickness of the thick plate, and the fillet weld is deep penetration welding. S4. Prepare before welding: clean the area around the groove to ensure there is no dirt within 20mm of the two edges of the groove, preheat the thick plate, and perform tack welding on the thick plate; S5. Formal welding of thick plates: When welding the panels, weld the front weld first, then turn the panels over and clean the roots with carbon planers. When cleaning the roots with carbon planers, make the bottom opening of the weld groove as large as possible, and weld the back of the weld after polishing. When using submerged arc automatic welding, install arc starting and arc ending plates between the starting and ending ends of the weld. The thickness difference between the arc starting and arc ending plates of the panel weld and the weldment is plus or minus 2mm. The size of the arc starting and arc ending plates is 150×150mm. The arc starting length is not less than 80mm, and the arc extinction length is not less than 50mm. When using multi-pass and multi-layer welding, the welding should maintain continuity, the interlayer temperature should be above the preheating temperature, the welding slag and spatter should be removed after each weld, and the joints of each weld should be staggered to At least 30 to 50 mm; when welding longitudinal bones, heat while welding, and an even number of welders weld on both sides of the longitudinal bones at the same time, and use the step-by-step retreat welding method or the center welding method for welding; when the component and the plate seam intersect, if there are both butt joints and fillet welds, weld the butt welds first, then weld the fillet welds, and weld the vertical fillet welds first and then the flat fillet welds; when the weld height of the plate affects the tight installation of the component, grind the weld height, and the grinding length should not be less than the thickness of the component plate, or open a through welding hole; fill the arc crater at the end of the weld, and the through welding hole or the leak-proof hole has a good wrap angle; if the wind speed is greater than 2 meters per second during outdoor welding, windproof measures need to be taken around the weld, and do not weld in the open air when it rains.
2. The welding method according to claim 1, characterized in that The grade of the thick plates at the hatch coamings in S1 is EH47 steel, the grade of the thick plates at the main deck is EH40 steel, the grade of the thick plates at the shell plating is EH40, DH32 or AH32 steel, the grade of the thick plates at the longitudinal bulkheads is EH40, DH32 or AH32 steel, and the grade of the thick plates at the longitudinals is AH40, AH32 or HP300*12AH bulb flat steel.
3. The welding method according to claim 2, characterized in that In S2, if the steel grades of the thick plates to be welded are EH47 and EH40 respectively, the welding method is CO2 gas shielded semi-automatic welding, CO2 automatic fillet welding machine or single-wire submerged arc automatic welding; if the steel grades of the thick plates to be welded are EH40 and AH40 respectively, the welding method is CO2 gas shielded semi-automatic welding or CO2 automatic fillet welding machine; if the steel grades of the thick plates to be welded are EH47 and EH40 respectively, the welding method is CO2 gas shielded semi-automatic welding, CO2 automatic fillet welding machine or single-wire submerged arc automatic welding; if the steel grades of the thick plates to be welded are EH47, EH40 and EH36 and below respectively, the welding method is CO2 gas shielded semi-automatic welding, CO2 automatic fillet welding machine or single-wire submerged arc automatic welding; if the steel grade of the thick plates to be welded is EH36 and below, the welding method is CO2 gas shielded semi-automatic welding, CO2 automatic fillet welding machine or single-wire submerged arc automatic welding.
4. The welding method according to claim 1, wherein: The length of the tack weld in S4 is not less than 50mm, the spacing of the tack welds is 300-500mm, and the welding materials used for tack welding are of the same grade as those used for formal welding. If there are welding defects in the tack weld, the tack weld with welding defects needs to be removed and re-tack welded. All EH47 steel plates need to be preheated to above 100°C.
5. The welding method according to claim 1, wherein: In the S5, during the carbon dioxide gas shielded welding process, a welding wire with a diameter of 1.2 mm is selected; during the submerged arc welding process, a welding wire with a diameter of 4.0 mm is selected.
6. The welding method according to claim 5, characterized in that In said S5, during the bottom welding: in the process of flat welding with submerged arc welding, the welding current is 600-700A; in the process of vertical welding with carbon dioxide gas shielded welding, the welding current is 230-260A; in the process of horizontal welding with carbon dioxide gas shielded welding, the welding current is 180-210A; in the process of overhead welding with carbon dioxide gas shielded welding, the welding current is 210-240A; When welding the filler pass: in the process of submerged arc welding, the welding current is 610-710A; in the process of vertical welding with carbon dioxide gas shielded welding, the welding current is 235-265A; in the process of horizontal welding with carbon dioxide gas shielded welding, the welding current is 180-210A; in the process of overhead welding with carbon dioxide gas shielded welding, the welding current is 210-240A; When welding the cap weld: in the process of submerged arc welding, the welding current is 600-690A; in the process of vertical welding with carbon dioxide gas shielded welding, the welding current is 210-240A; in the process of horizontal welding with carbon dioxide gas shielded welding, the welding current is 175-205A; in the process of overhead welding with carbon dioxide gas shielded welding, the welding current is 205-235A.
7. The welding method according to claim 1, wherein: In the S5, the voltage is controlled at 25-36V during carbon dioxide gas shielded welding. When carbon dioxide gas shielded welding uses multi-layer welds, the swing width of each weld is controlled within 10 times the wire diameter, and the welding speed is controlled between 440-550mm / min. When submerged arc welding uses multi-layer welds, the welding speed is controlled between 450-550mm / min. When there are multi-layer welds, the thickness of each weld layer is controlled between 3-5mm. During the entire welding process, the interlayer temperature is below 250°C.
8. The welding method according to claim 1, wherein: S5 also includes the principles of welding sequence: longer butt welds should generally be welded from the middle to both ends; when butt welds and fillet welds exist in a component at the same time, the butt welds should be welded first and then the fillet welds; welds that do not form rigid constraints on the shrinkage of other welds should be welded first, then the constraint welds, and the main components should be welded first and then the secondary components; when welding each weld, keep one end of it with room for free shrinkage; because the lateral shrinkage of the weld is greater than the longitudinal shrinkage, when welding the plate row, the end joints should be welded first, then the side joints, and finally the flush transverse joints; when welding the frame and the plate seam, the plate seam should be welded first, then the butt welds between the frames, and finally the fillet joints between the frame and the plate; the welding of segments should be done symmetrically by multiple people, starting from the center of the segment and expanding to the surrounding areas; when welding the large closing seam of the total segment, a symmetrical welding sequence should be adopted to ensure uniform shrinkage on both sides of the neutral axis; flat fillet welds are not allowed to be excessively biased towards the plate.