A method of welding a plate
By forming X-shaped or K-shaped bevels on both sides of medium-thick plates, and combining CO2 gas shielded welding and submerged arc welding, assembly gaps are eliminated, and filler welds are directly performed. This solves the problems of deformation control difficulty and low efficiency in full penetration welding of medium-thick plates, and achieves efficient and precise welding.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- WUCHUAN HEAVY ENG
- Filing Date
- 2023-05-17
- Publication Date
- 2026-06-09
AI Technical Summary
When welding medium and thick plates with full penetration, existing technologies require carbon arc gouging and grinding to clean the root, which makes it difficult to control welding deformation, involves a large workload, and is inefficient.
The welding method employs an X-shaped or K-shaped bevel on both sides of the plate to perform root pass welding and penetration welding, eliminating assembly gaps and directly performing filler welds. It eliminates the need for carbon arc gouging and grinding, and combines CO2 gas shielded welding and submerged arc welding.
It simplifies the construction process, reduces the difficulty and cost of controlling welding deformation, improves welding efficiency, reduces slag generation, is suitable for fully automated robotic welding, and enables welding with higher precision and quality.
Smart Images
Figure CN116551123B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the technical field of welding processes, and in particular to a welding method for medium and thick plates. Background Technology
[0002] When full penetration welding is required on sheet metal, a combination of gas shielded welding (GSAW) and submerged arc welding (SAW) is commonly used. First, GSAW is used for the root pass on the front side, followed by SAW for the fill and cap passes. Then, carbon arc gouging and grinding are performed on the back side, followed by another GSAW root pass. Finally, SAW is used for the fill and cap passes. For medium to thick sheet metal, especially those thicker than 25mm, root cleaning is unavoidable. The weld bevel must be cleaned until the front weld is visible before welding the reverse side. This process presents challenges such as difficulty in controlling welding deformation, a large workload, numerous procedures, and low efficiency. Summary of the Invention
[0003] The purpose of this invention is to address the problems in related technologies regarding the welding process of medium and thick plates for full penetration, which requires carbon arc gouging and grinding, resulting in difficulties in controlling welding deformation, large welding workload, and low efficiency. This invention provides a welding method for medium and thick plates that eliminates the need for carbon arc gouging and grinding, thereby reducing the difficulty in controlling welding deformation, simplifying construction procedures, reducing welding workload, and effectively improving construction efficiency.
[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0005] A method for welding medium-thick plates includes the following steps: a bevel prefabrication step: processing the weldable portion of the plate into an X-shaped or K-shaped bevel; a root pass welding step: performing root pass welding in the bevels on the front and back sides of the plate respectively, forming a preset weld thickness; a penetration weld root step: performing penetration filler weld in the bevels on the front and / or back sides of the plate, so that the root pass weld root can be fully penetrated; and a filler weld step: performing filler weld in the bevels on the front and back sides of the plate until the weld is filled.
[0006] In some alternative embodiments, in the bevel prefabrication step, the bevel is not left with a blunt edge, and in the root pass welding step, the weld thickness on the front and back of the plate is 3mm to 4mm.
[0007] In some optional embodiments, in the root pass welding step, CO2 gas shielded welding is used to perform one root pass welding in the bevel on both the front and back sides of the plate. The welding wire used for the root pass welding has a diameter of 1.2 mm, a current of 250A to 280A, a voltage of 30V to 33V, and a welding speed of 440mm / min to 460mm / min.
[0008] In some alternative embodiments, during the penetration weld root step, a penetration filler weld is performed in the bevel on both the front and back sides of the plate using submerged arc welding.
[0009] In some optional embodiments, during the penetration welding root step, when performing the penetration filler welding on the front side of the plate, the submerged arc welding wire used has a diameter of 4 mm, a current of 710A to 730A, a voltage of 28V to 32V, and a welding speed of 600mm / min to 620mm / min.
[0010] In some alternative embodiments, during the penetration welding root step, when performing the penetration filler welding on the back side of the plate, the submerged arc welding wire used has a diameter of 4 mm, a current of 810A to 830A, a voltage of 28V to 32V, and a welding speed of 600mm / min to 620mm / min.
[0011] In some optional embodiments, in the beveling prefabrication step, the part of the plate to be welded is a T-joint, and the part of the plate to be welded is processed into a K-shaped bevel, and the angle of the bevel on the front and back of the plate is 45 degrees to 55 degrees.
[0012] In some alternative embodiments, during the beveling prefabrication step, the bevels on the front and back sides of the slab are symmetrical to each other.
[0013] In some optional embodiments, the assembly gap at the welded joint of the plate is 0 mm to 2 mm.
[0014] In some optional embodiments, in the filling weld step, the groove is filled by submerged arc welding with a current of 620A to 700A, a voltage of 32V to 34V, a welding speed of 480mm / min to 500mm / min, and a weld leg size of 5mm to 7mm.
[0015] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:
[0016] This invention discloses a welding method for medium-thick plates. By performing root pass welding on the bevels on both sides of the plate, the X-type or K-type bevel is transformed into a double U-type bevel. This eliminates assembly gaps before the root pass welding, ensuring a better weld penetration. The penetration allowance provided by the root pass welding allows for direct filling of the weld seam after the root pass welding, eliminating the need for carbon arc gouging and grinding. This method not only meets the requirement of full penetration welding for medium-thick plate joints but also simplifies the construction process, reduces the amount of welding materials used, effectively reduces the difficulty of controlling welding deformation and construction costs, and eliminates the need for manual carbon arc gouging, thus reducing slag generation, protecting the industrial environment, and providing feasibility for fully automated robotic welding. This enables higher precision and higher quality welding operations. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0018] Figure 1 This is a flowchart of the medium-thick plate welding method described in the embodiment;
[0019] Figure 2 This is a schematic diagram of the bevel of the I-beam described in the embodiment;
[0020] Figure 3 This is a schematic diagram of the bevels of the wing plate and the web plate described in the embodiment;
[0021] Figure 4 This is a schematic diagram of the root pass weld as described in the embodiment;
[0022] Figure 5 This is a schematic diagram of the structure where the bevel is filled with weld seam as described in the embodiment;
[0023] The markings in the diagram are: 110 - web, 120 - flange, 130 - bevel, 140 - root pass weld, 150 - front filler weld, and 160 - back filler weld. Detailed Implementation
[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0025] It should be noted that all directional indications in the embodiments of the present invention are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.
[0026] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.
[0027] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.
[0028] This application is described below with reference to the accompanying drawings and specific embodiments:
[0029] Example
[0030] Composite steel plate girders have the characteristics of large span and efficient construction, and are widely used. Among them, the weld of the T-joint at the connection between the flange and the web of the steel plate girder is extremely critical. Full penetration welding is usually required. The traditional welding method uses a combination of CO2 gas shielded welding and submerged arc welding. That is, CO2 gas shielded welding is used for the root pass on the front side, submerged arc welding is used for the fill and cover passes, carbon arc gouging is used for the back side, and after grinding with a grinding wheel, CO2 gas shielded welding is used for the root pass again, and then submerged arc welding is used for the fill and cover passes. The whole welding process has problems such as large welding workload, complicated welding procedures, and large welding deformation.
[0031] When the web thickness of a T-joint is relatively thin (generally less than 16mm), double-sided submerged arc welding can achieve root-cleaning-free full penetration welding. However, when the web thickness of a T-joint is relatively thick, especially when the web thickness is greater than 25mm, double-sided submerged arc welding cannot achieve root-cleaning-free full penetration welding. Therefore, full penetration welding of thick plate T-joints is a major technical challenge in the industry. To meet the requirements for full penetration welding of thick plate T-joints in steel plate beams, and at the same time simplify the construction process, effectively reduce the difficulty of welding deformation control, reduce procedures, and lower construction and manufacturing costs, [further details needed]. Figure 1 As shown, the present invention provides a welding method for medium-thick plates, comprising the following steps:
[0032] Beveling prefabrication steps: The part of the plate to be welded is processed into an X-shaped or K-shaped bevel;
[0033] Root pass welding step: Perform root pass welding in the bevels on the front and back of the plate respectively, and form the preset weld thickness;
[0034] Penetration weld root step: Perform penetration filler weld within the bevel on the front and / or back of the plate to ensure full penetration of the root of the root weld; and,
[0035] Filler weld procedure: Perform filler welds in the bevels on the front and back sides of the plate until the weld is filled.
[0036] In the beveling prefabrication step, medium-thick plates are plates with a thickness of 16mm or more. The choice between X-type or K-type beveling depends on the type of welded joint of the plates. For example, if the welded joint is a butt joint, the weldable parts of both plates can be processed according to the welding requirements and combined to form an X-type beveling. If the welded joint is a T-type joint, the weldable part of one plate can be beveled according to the welding requirements and then spliced with the other plate to form a K-type beveling.
[0037] In the root pass welding step, the weld thickness is mainly determined by two factors. First, if the weld thickness is too small, burn-through is likely to occur in the subsequent penetration filler weld, making it impossible to avoid root cleaning and grinding. Second, if the weld thickness is too large, penetration will be difficult to achieve during the penetration filler weld, which may lead to incomplete penetration at the weld root and fail to meet the requirements for full penetration. The predetermined weld thickness is determined based on the method of the penetration filler weld step for the weld thickness on the front and back of the plate. If full penetration is achieved by performing only one penetration filler weld on the front or back of the plate, the weld thickness of the root pass on the side where the penetration filler weld is performed cannot be too large, while the weld thickness of the root pass on the other side cannot be too small.
[0038] For example, in the root pass welding step, the preset weld thicknesses for the front and back sides of the plate can be designed to be different. The weld thickness on the front side is controlled to a level that facilitates penetration during the filler weld, while the weld thickness on the back side can be greater than that on the front side. In other words, the weld thickness on the back side does not need to consider whether it is easy to penetrate during the filler weld step, but rather ensures that the filler weld is not easily burned through. This allows for the option of performing only one filler weld on the front side during the root pass welding step. By controlling the penetration depth of the first filler weld on the front side, the root pass weld on the front side can be completely melted away. Due to the instability of the welding process, the design of the root pass weld on the back side can provide a larger margin, allowing the first filler weld on the front side to penetrate into the root pass weld on the back side without easily burning through it. This provides greater feasibility and practicality for achieving full penetration at the root of the root pass weld in actual working conditions.
[0039] This invention discloses a welding method for medium-thick plates. By performing root pass welding on the bevels on both sides of the plate, an X-type or K-type bevel is transformed into a double U-type bevel. Compared to directly machining the plate into a U-type bevel, this method eliminates assembly gaps before performing the full penetration weld, ensuring a better welding effect. It also eliminates the need for the stringent requirement of zero gaps during plate assembly, making it particularly suitable for welding large workpieces. Furthermore, it avoids the high cost of machining U-type bevels. The penetration allowance provided by the root pass welding allows for direct full penetration weld operation after the root pass welding, eliminating the need for carbon arc gouging and grinding. This method satisfies the requirement for full penetration welding of medium-thick plate joints, simplifies the construction process, effectively reduces the difficulty of controlling welding deformation and manufacturing costs, and eliminates the need for manual carbon arc gouging, reducing slag generation and protecting the industrial environment. It also provides feasibility for fully automated robotic welding, thereby achieving higher precision and higher quality welding operations.
[0040] In some alternative implementations, the bevel is not left with a blunt edge in the bevel prefabrication step, and the weld thickness on the front and back of the plate is 3mm to 4mm in the root pass welding step.
[0041] In the bevel prefabrication step, no blunt edge is left when prefabricating the bevel. This not only reduces the difficulty and requirements of bevel processing, but also forms an X-type or K-type bevel without a blunt edge. This can effectively reduce the depth required for penetration welding root, resulting in a smaller current required for penetration welding. It is also easier to precisely control the penetration depth during welding, thereby better achieving the purpose of not cleaning the root and grinding. In addition, a certain thickness is formed between the bevels on the front and back of the plate through the root pass welding, achieving an effect similar to a blunt edge. Therefore, no blunt edge is left when processing the plate, which also makes it easier to control the preset value of the weld thickness.
[0042] In the root pass welding step, the weld thickness of both the front and back passes is controlled within 3mm to 4mm. Controlling the weld thickness within this range balances the effects of excessively thin or thick welds, making it less prone to burn-through in subsequent penetration filler welds while still achieving full penetration. Designing the weld thicknesses of the front and back passes to be roughly equal is particularly suitable for the root pass welding step, where a single penetration filler weld is performed on both the front and back passes. This combination of two penetration filler welds ensures full penetration at the root of the root pass weld. Compared to achieving full penetration with only one penetration filler weld in the root pass welding step, the latter penetration filler weld can compensate for and eliminate incomplete penetration defects caused by operational errors in the previous penetration filler weld, reducing the difficulty of the penetration filler weld construction. This further improves the feasibility and practicality of the process, ensuring the stability of full penetration at the weld root along the entire length of the plate, and making it more suitable for in-workshop processing.
[0043] In some optional embodiments, in the root pass welding step, CO2 gas shielded welding is used to perform one root pass welding in the bevel on both the front and back sides of the plate. The welding wire used for the root pass welding has a diameter of 1.2mm, a current of 250A to 280A, a voltage of 30V to 33V, and a welding speed of 440mm / min to 460mm / min. CO2 gas shielded welding under these parameters can form a weld thickness of 3mm to 4mm. Using CO2 gas shielded welding as the root pass welding method has high welding efficiency and good cost performance.
[0044] In some alternative implementations, in the penetration weld root step, submerged arc welding is used to perform one penetration filler weld on each of the bevels on the front and back sides of the plate. If the penetration weld root step is completed by only one penetration filler weld, the welding accuracy requirements for this step are high and the difficulty is relatively large. Manual operation is bound to have errors or large errors. When the weld thickness on both the front and back sides of the plate is controlled at 3mm to 4mm, choosing to complete the penetration weld root step by combining two penetration filler welds can effectively reduce the welding difficulty and increase the error tolerance of full penetration welding. Using submerged arc welding as the welding method for penetration filler weld is especially suitable for medium and thick plates and has high welding efficiency.
[0045] In some optional embodiments, during the root penetration welding step, when performing a full penetration filler weld on the front side of the plate, the submerged arc welding wire used has a diameter of 4mm, a current of 710A to 730A, a voltage of 28V to 32V, and a welding speed of 600mm / min to 620mm / min. For the preset weld thickness of 3mm to 4mm for the root pass, this parameter is used to perform a submerged arc weld at one side of the plate bevel. This allows the submerged arc weld to penetrate the weld of the root pass on one side, making it easy to achieve full penetration of the root, while ensuring that the penetration depth does not burn through the weld of the root pass on the other side. That is, the penetration depth of this submerged arc weld is controlled to be approximately between 4mm and 6mm.
[0046] In some optional implementations, during the root penetration welding step, when performing a root penetration filler weld on the back side of the plate, the submerged arc welding wire diameter is 4mm, the current is 810A~830A, the voltage is 28V~32V, and the welding speed is 600mm / min~620mm / min. For the weld formed by a submerged arc weld on one side of the plate bevel, a second submerged arc weld is performed on the opposite side of the plate bevel using the same parameters, with a higher current and deeper penetration than the previous submerged arc weld. This further ensures full root penetration, greatly improving the reliability of the process. Furthermore, because the previous submerged arc weld increased the penetration allowance on one side of the plate, it ensures that when performing a root penetration weld on the other side of the plate bevel using these parameters, the previous submerged arc weld will not burn through, thus avoiding the need for root cleaning.
[0047] In some optional embodiments, in the beveling prefabrication step, the part of the plate to be welded is a T-joint, and the part of the plate to be welded is processed into a K-shaped bevele, and the beveling angles on the front and back of the plate are 45 degrees to 55 degrees; for the welding of T-joints, controlling the beveling angle within the range of 45 degrees to 55 degrees can effectively ensure the weld strength of medium and thick plates.
[0048] In some alternative implementations, the bevels on the front and back sides of the plate are symmetrical during the bevel prefabrication step. Compared to processing to form an asymmetrical bevel or performing staggered welding to form an asymmetrical bevel, welding with symmetrical bevels on the front and back sides can effectively reduce the generation of welding deformation and reduce the difficulty of controlling welding deformation.
[0049] In some optional embodiments, the assembly gap at the welded joint of the plate is 0mm to 2mm. Since a double U-shaped bevel is formed after the root pass weld on both the front and back sides of the plate, and there is no assembly gap when performing the penetration weld, the assembly gap of the plate can be determined according to the conventional process requirements before the root pass weld. There is no need to additionally require the plate to achieve zero gap during assembly, which ensures the effect of penetration welding. At the same time, it reduces the difficulty of assembly and makes it easier to weld large workpieces. Because the assembly gap of large workpieces is unavoidable, the difficult-to-eliminate assembly gap in the penetration welding of large workpieces greatly affects the effect of penetration welding and brings trouble to root cleaning and grinding.
[0050] In some alternative implementations, during the filler weld step, submerged arc welding is used to fill the groove with a current of 620A to 700A, a voltage of 32V to 34V, a welding speed of 480mm / min to 500mm / min, and a weld leg size of 5mm to 7mm. Submerged arc welding performed under these parameters can efficiently complete the filler weld and capping process.
[0051] In some practical working conditions, such as welding work for an I-beam formed by two side flanges 120 and a central web plate 110, for example... Figure 2 and Figure 3 As shown, the thickness of the web 110 is 36 mm. The web 110 and the flange 120 form a T-joint. When implementing the welding process of the present invention, certain combinations were made among various optional schemes, specifically:
[0052] The prefabrication steps for bevel 130 are as follows: the front and back sides of the web plate 110 are both machined to form 45-degree bevels 130 that are symmetrical to each other, without leaving blunt edges. The gap between the web plate 110 and the flange plate 120 is controlled at 0-2mm to form a K-type bevel 130.
[0053] Perform the root pass welding step: as follows Figure 4 As shown, for the bevels 130 on the front and back sides of the web 110, CO2 gas shielded welding is used to perform the root pass welding operation sequentially on the jig. The diameter of the flux-cored wire is 1.2mm, the welding current is 250A~280A, the arc voltage is 30V~33V, and the welding speed can be 440mm / min~460mm / min. For example, a welding speed of 440mm / min or 460mm / min can be selected, especially a welding speed of 450mm / min, which has a good welding effect. During the operation, the thickness of the root pass weld 140 on both sides is controlled to be 3mm~4mm.
[0054] The step of performing a full penetration weld root: Submerged arc welding is used on the flipping jig, such as... Figure 5As shown, a full penetration filler weld is sequentially performed on the root pass weld 140 on both the front and back sides of the plate using submerged arc welding with a wire diameter of 4.0 mm. When welding the root pass weld 140 on one side first, the welding current is 710A~730A, the arc voltage is 28V~32V, and the welding speed is 600mm / min~620mm / min, forming a front filler weld 150. Then, when welding the root pass weld 140 on the other side, the welding current is 810A~830A, the arc voltage is 28V~32V, and the welding speed is 600mm / min~620mm / min, forming a back filler weld 160. By performing a full penetration filler weld on each of the root pass welds 140 on both sides, the root of the weld is fully penetrated, and no burn-through occurs, while the slag removal performance is good.
[0055] The filling weld procedure is as follows: Based on the thickness of the web plate 110, the welds on both the front and back sides of the web plate 110 are performed using five layers and seven passes. Submerged arc welding is used to continue filling the remaining weld passes and performing the final cover weld. The welding current is 620A~700A, the arc voltage is 32V~34V, and the welding speed is 480mm / min~500mm / min. After welding, the weld leg size is ensured to be 5mm~7mm.
[0056] Similarly, the principle and steps of this process are also applicable to some other welding joint types of medium and thick plates. When applying it, the type of bevel can be selected according to the actual working conditions, and the bevel angle, as well as the number of weld passes and layers when filling the weld, can be adjusted.
[0057] One or more embodiments provide a medium-thick plate welding method that creatively uses CO2 gas shielded welding to prefabricate the bevel 130 for the root pass, transforming the K-type bevel 130 into a double U-type bevel 130. The two bevels 130 on the front and back are symmetrical to each other, and a certain blunt edge is re-formed between the two bevels 130 through the root pass welding. Compared with directly machining the plate into a U-type bevel 130, it can eliminate the assembly gap before performing the full penetration welding, which is conducive to ensuring the welding effect of full penetration. In addition, it does not require the harsh condition of zero gap during plate assembly. It is especially suitable for welding and assembling large workpieces, and also avoids the high cost of machining to open the U-type bevel 130, effectively reducing the consumption of welding materials and reducing processing costs.
[0058] Furthermore, by performing a high-current filler weld on each of the 130° bevels on both sides using submerged arc welding, the weld penetration effect can be effectively and stably guaranteed. This method is highly feasible and reliable in actual working conditions, providing excellent assurance for welding quality. The entire process utilizes the concentrated heat energy and deep penetration of the submerged arc welding arc, eliminating the need for existing carbon arc gouging and grinding processes. This not only meets the welding requirements for full penetration of medium and thick plate joints but also simplifies the construction process, effectively reducing the difficulty of controlling welding deformation and construction costs. Furthermore, eliminating the need for manual carbon arc gouging reduces slag generation, protects the industrial environment, and facilitates the integration with cutting-edge technologies, providing feasibility for fully automated robotic welding. This leads to higher precision and higher quality welding operations and has broad application prospects.
[0059] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.
Claims
1. A method for welding medium-thick plates, characterized in that, Includes the following steps: Beveling prefabrication steps: The part of the plate to be welded is processed into an X-shaped or K-shaped bevel; Root pass welding step: Perform root pass welding in the bevels on the front and back sides of the plate respectively, and form a preset weld thickness; Penetration weld root step: Perform penetration filler welds within the bevels on both the front and back sides of the plate to ensure full penetration of the root weld of the root pass; and, Filling weld step: Perform filler welds in the bevels on the front and back sides of the plate until the weld is filled; In the bevel prefabrication step, the bevel is not left with a blunt edge. In the root pass welding step, the weld thickness on the front and back of the plate is 3mm to 4mm.
2. The welding method for medium-thick plates according to claim 1, characterized in that, In the root pass welding step, CO2 gas shielded welding is used to perform one root pass welding in the bevel on both the front and back sides of the plate. The welding wire used for the root pass welding has a diameter of 1.2 mm, a current of 250A~280A, a voltage of 30V~33V, and a welding speed of 440mm / min~460mm / min.
3. The welding method for medium-thick plates according to claim 1, characterized in that, In the penetration welding root step, a penetration filler weld is performed in the bevel on both the front and back sides of the plate using submerged arc welding.
4. The welding method for medium-thick plates according to claim 3, characterized in that, In the penetration welding root step, when performing the penetration filler welding on the front side of the plate, the submerged arc welding wire used has a diameter of 4mm, a current of 710A~730A, a voltage of 28V~32V, and a welding speed of 600mm / min~620mm / min.
5. The welding method for medium-thick plates according to claim 4, characterized in that, In the penetration welding root step, when performing the penetration filler welding on the back side of the plate, the submerged arc welding wire used has a diameter of 4mm, a current of 810A~830A, a voltage of 28V~32V, and a welding speed of 600mm / min~620mm / min.
6. The welding method for medium-thick plates according to claim 1, characterized in that, In the beveling prefabrication step, the part of the plate to be welded is a T-joint. The part of the plate to be welded is processed into a K-shaped bevele, and the angle of the bevele on the front and back of the plate is 45 degrees to 55 degrees.
7. The welding method for medium-thick plates according to claim 1, characterized in that, In the beveling prefabrication step, the beveles on the front and back of the plate are symmetrical to each other.
8. The welding method for medium-thick plates according to claim 1, characterized in that, The assembly gap at the welded joint of the plate is 0mm~2mm.
9. The welding method for medium-thick plates according to any one of claims 1 to 8, characterized in that, In the filling weld step, the groove is filled by submerged arc welding with a current of 620A~700A, a voltage of 32V~34V, a welding speed of 480mm / min~500mm / min, and a weld leg size of 5mm~7mm.