Single-face submerged arc automatic welding method

Abstract

The invention discloses an automatic single-face submerged arc welding method. The automatic single-face submerged arc welding method comprises the following steps that S1, a steel plate is assembled; s2, positioning butt joints of the steel plates and mounting arc striking and extinguishing plates; s3, an FGB gasket is fixedly installed on the reverse side of the butt joint of the steel plates; s4, welding iron powder is locally laid in the large-gap area, the large-gap area is filled with the welding iron powder, and the welding iron powder is flush with the surface of the steel plate; s5, FGB single-face submerged arc automatic welding is carried out; carrying out FGB method single-side submerged arc automatic welding on the front side of the butt joint of the steel plate by adopting pulsed arc submerged arc automatic welding equipment; and S6, welding slag and an FGB gasket are removed. By means of the method, the splicing welding construction procedure of the butt joint of the steel plates can be simplified, groove-free single-face welding and double-face forming welding construction of the butt joint of the thin steel plates is achieved, the adaptability of submerged-arc welding to the gap of the spliced steel plates is improved, the welding quality and efficiency of the submerged-arc welding are improved, and the welding deformation and energy consumption of automatic submerged-arc welding of the spliced steel plates are reduced; welding material consumption is reduced, and comprehensive construction cost is saved.

Description

Technical Field

[0001] The invention relates to the technical field of ship welding, in particular to a single-sided submerged arc automatic welding method. Background Art

[0002] Currently, in the field of shipbuilding and other large steel structure construction, there is a lot of pre-welding work for steel plate splicing. During the steel plate welding construction process, submerged arc automatic welding is generally used for welding. There are two existing solutions, as follows: Solution 1: Double-sided submerged arc automatic welding: Figures 1 to 6 As shown, first weld all the butt joints of the first welded surface on a flat ground, then turn over the assembled multiple steel plates as a whole, and then weld all the butt joints of the subsequent welded surface. The specific process of Scheme 1 is as follows: (1) Steel plate assembly: On a flat ground or a welding platform, splice multiple first steel plates 100 together flatly, see Figure 1 (2) Fixing and welding the butt joints of the steel plates and installing the arc striking and extinguishing plates: Fix all the first butt joints of the steel plates 101 that are spliced together by positioning welding (using manual arc welding or semi-automatic CO2 gas shielded welding) and install the first arc striking and extinguishing plates 104, see Figure 2 As shown, all welding slags of the first positioning weld 103 need to be thoroughly cleaned; (3) Welding of the first large gap area 102: Pre-welding is performed on the area where the local assembly gap is greater than 1.5 mm, which is generally done by manual arc welding or semi-automatic CO2 gas shielded welding, see Figure 3 As shown, the welding slag of the large gap welding seam 105 needs to be completely cleaned; (4) Front submerged arc automatic welding: Submerged arc automatic welding is performed on each first steel plate butt joint 101. The front weld 106 does not penetrate the entire plate thickness. Figure 4 (5) Turning over the steel plate and cleaning the reverse side: Turn the first steel plate 100 180 degrees and place it flat; clean the first large gap area 102, which is prone to slag inclusion or weld defects, and may produce weld defects and slag inclusion areas 107. Figure 5 (6) Reverse side submerged arc automatic welding: perform submerged arc automatic welding on each first steel plate butt joint 101, and the reverse side weld 108 and the front side weld 106 penetrate the entire plate thickness, see Figure 6 shown.

[0003] The disadvantages and reasons of Scheme 1 are as follows: (1) Double-sided welding requires lifting equipment to cooperate with turning over, which occupies a large amount of lifting equipment resources; two pre-welding preparations (i.e. drawing lines, laying rails, installing welding trolleys, preparing welding wires and flux, etc.) and post-welding recovery work are required, and the preparation and completion workload is large; the welding time is long and the welding efficiency is low; during the first welding process, the first steel plate butt joint 101 has an asymmetric weld shape and asymmetric cooling shrinkage in the thickness direction, and the angular deformation on both sides of the weld is large, and the post-weld leveling workload and difficulty are large; (2) The first large gap area 102 needs to be pre-welded, and the welding construction efficiency is low. The welding is prone to slag inclusions or weld nodules, and the defect handling workload is large; (3) There is no padding support on the back of the first steel plate butt joint 101. When the front is submerged arc automatic welding, the first large gap area 102 is prone to weld nodules or burn-throughs, and the defect handling workload is large.

[0004] Option 2: Use single-sided FGB submerged arc automatic welding with groove opening: Figures 7 to 12 As shown, the welding groove of the area to be spliced is pre-processed on the steel plate, and then the steel plate is assembled and fixed on a special frame, and then FGB submerged arc automatic welding is performed. Among them, FGB single-sided submerged arc automatic welding is a high-efficiency submerged arc automatic welding method assisted by FGB pads (i.e. special ceramic pads with glass fiber cloth), which can achieve single-sided welding and double-sided forming. The specific process of scheme 2 is as follows: (1) Beveling the steel plate: Beveling 201 (i.e. processing the bevel) on all edges of the second steel plate 200 to be spliced according to the design requirements, see Figure 7 (2) Steel plate assembly: Assemble the second steel plate 200 with the groove 201 flatly together, see Figure 8 (3) Position welding and fixing of the steel plate butt joint and installation of the arc-extinguishing plate: Position welding is performed in the groove 201 of the second steel plate butt joint 202, and the second arc-extinguishing plate 204 is fixed at both ends of the second steel plate butt joint 202, see Figure 9 As shown, reference numeral 203 is the second positioning weld; (4) Installing the FGB gasket: Install and fix the first FGB gasket 205 on the reverse side of the second steel plate butt joint 202. The center of the first FGB gasket 205 corresponds to the center of the second steel plate butt joint 202. The two are tightly attached by self-adhesive glue. Figure 10 (5) Laying iron powder: Lay the first welding iron powder 206 in the groove 201 of the second steel plate butt joint 202. The laying thickness of the first welding iron powder 206 is flush with the surface of the second steel plate 200. Figure 11 As shown; (6) FGB single-sided submerged arc automatic welding is performed; FGB single-sided submerged arc automatic welding is performed on the front of the second steel plate butt joint 202, and the welding construction of the second steel plate butt joint 202 is completed by the single-sided welding and double-sided forming welding process, see Figure 12 As shown, reference numeral 207 is the first weld.

[0005] The disadvantages and reasons of the second solution are as follows: (1) The second steel plate 200 needs to be pre-cut with a groove 201: there are many construction processes and the construction efficiency is low; the groove 201 is generally cut by thermal cutting, which can easily cause the second steel plate 200 to deform during the thermal cutting process, especially in the cutting area. The deformed second steel plate 200 will increase the difficulty of subsequent assembly and leveling; the cross-sectional area of the second steel plate joint 202 that needs to be welded is large, which consumes more welding materials, slows the welding speed, takes a long time, consumes more electricity, and has a high welding heat input. (i.e. welding current × welding voltage ÷ welding speed) is large, the peak temperature at the center of the weld is high, the high-temperature residence time of the weld is long, the burn-off amount of beneficial alloy elements is large, and the mechanical properties of the weld are poor; the second steel plate butt joint 202 after the panel assembly is in a V-shaped cross-sectional shape, and the cross-sectional shape of the first weld 207 formed after FGB submerged arc automatic welding is also close to V-shaped, the cooling shrinkage of the first weld 207 on the front and back sides of the second steel plate 200 is asymmetric, and the upward angular deformation of the first weld 207 on both sides of the front side of the second steel plate 200 is large.

[0006] In addition, the welding current output by conventional submerged arc automatic welding equipment is generally DC or AC, and the welding current magnitude remains basically unchanged. The welding wire feed speed must match the welding current magnitude to maintain the relative stability of the wire dry extension length and welding voltage. When welding steel plate butt joints without grooves and gaps (i.e., I-type groove butt joints), in order to ensure the depth of weld penetration, the welding current needs to be increased (and the wire feed speed is increased simultaneously). Because the I-type groove does not have sufficient cross-sectional space to carry the weld metal like the V-type groove, excess weld metal can only accumulate on the surface of the steel plate. Excessive weld metal accumulation on the steel plate surface directly leads to excessive weld height and deterioration of the weld surface forming quality. In addition, the welding heat input of conventional submerged arc automatic welding is large, and the mechanical properties of the weld metal are poor. Summary of the Invention

[0007] The purpose of the present invention is to provide a single-sided submerged arc automatic welding method, which can simplify the splicing welding construction process of the third steel plate butt joint, realize the grooveless single-sided welding and double-sided forming welding construction of the butt joint of thinner steel plates (10 mm and below in thickness), improve the adaptability of submerged arc welding to the gap between the third steel plate splices, improve its welding quality and welding efficiency, reduce the welding deformation and welding energy consumption of the submerged arc automatic welding of the third steel plate splices, and at the same time reduce the consumption of welding materials and save comprehensive construction costs.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is: A single-sided submerged arc automatic welding method comprises the following steps: Step S1: Steel plate assembly: providing a plurality of third steel plates, and assembling the third steel plates flatly together, forming a third steel plate butt joint between two adjacent third steel plates, wherein the third steel plate butt joint includes a second largest gap area and a small gap area; Step S2: Positioning the steel plate butt joint and installing the arc striking and extinguishing plates: performing tack welding on the third steel plate butt joint, and installing and fixing the third arc striking and extinguishing plates at both ends of the third steel plate butt joint in the extending direction; Step S3: Installing the FGB gasket: Installing and fixing the second FGB gasket on the reverse side of the butt joint of the third steel plate, wherein the center line of the second FGB gasket corresponds to the center line of the butt joint of the third steel plate; Step S4: Locally laying iron powder: locally laying second welding iron powder in the second large gap area, wherein the second welding iron powder fills the second large gap area and is flush with the surface of the third steel plate; Step S5: performing FGB single-sided submerged arc automatic welding: performing FGB single-sided submerged arc automatic welding on the front side of the butt joint of the third steel plate using a pulsed arc submerged arc automatic welding device, wherein the pulsed arc submerged arc automatic welding device alternately outputs peak current and base current to complete the welding construction of the butt joint of the third steel plate through a single-sided welding and double-sided forming welding process, and maintaining a constant welding speed during the welding process; Step S6: Removing welding slag and FGB liner: After welding is completed, the welding slag on the front side of the second weld formed by the FGB single-sided submerged arc automatic welding in step S5 and the second FGB liner on the back side are removed to complete the welding construction of the entire second weld.

[0009] As a preferred embodiment of the present invention, in step S2, after the third steel plate butt joint is tack welded, the welding slag on the third tack weld is removed.

[0010] As a preferred embodiment of the present invention, in step S2, the tack welding process is performed by manual arc welding or semi-automatic CO2 gas shielded welding.

[0011] As a preferred solution of the present invention, in step S3, the second FGB gasket and the third steel plate are tightly adhered to each other by self-adhesive glue.

[0012] As a preferred solution of the present invention, the gap in the second largest gap area is greater than 1.5 mm.

[0013] As a preferred embodiment of the present invention, in step S5, the diameter of the welding wire used in the FGB single-sided submerged arc automatic welding is 4.0 mm, and the dry extension length of the welding wire is 20-25 mm.

[0014] As a preferred embodiment of the present invention, in step S5, the peak current of the pulse arc submerged arc automatic welding equipment is 700-800 A, the peak voltage is 28-29 V, and the peak time is 0.5-1 s.

[0015] As a preferred embodiment of the present invention, in step S5, the base current of the pulse arc submerged arc automatic welding equipment is 500-550A, the base voltage is 28-29V, and the base time is 0.5-1s.

[0016] As a preferred embodiment of the present invention, in step S5, the welding speed of the pulse arc submerged arc automatic welding equipment is 27-30 m / h.

[0017] The single-sided submerged arc automatic welding method provided by the present invention has the following beneficial effects compared with the prior art: The present invention can simplify the splicing welding construction process of the third steel plate butt joint, realize the grooveless single-sided welding and double-sided forming welding construction of the butt joint of thinner steel plates (10 mm and below in thickness), improve the adaptability of submerged arc welding to the gap between the third steel plate splices, improve its welding quality and welding efficiency, reduce the welding deformation and welding energy consumption of the submerged arc automatic welding of the third steel plate splices, and at the same time reduce the consumption of welding materials, saving comprehensive construction costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings of the embodiments are briefly introduced below.

[0019] Figure 1 This is a schematic diagram of steel plate assembly in the first existing technical solution; Figure 2 This is a schematic diagram of the tack welding of the steel plate butt joint and the installation of the arc striking and extinguishing plate in the first existing technical solution; Figure 3 This is a schematic diagram of pre-welding at a large gap position in the prior art solution 1; Figure 4 This is a schematic diagram of front submerged arc automatic welding in the first existing technical solution (the first arc striking and extinguishing plate is hidden); Figure 5 This is a schematic diagram of the area where weld bead and slag inclusion defects occur in the first prior art solution; Figure 6 This is a schematic diagram of submerged arc automatic welding on the reverse side of the steel plate after turning over in the first existing technical solution; Figure 7 This is a schematic diagram of the steel plate beveling in the second existing technical solution; Figure 8 This is a schematic diagram of steel plate assembly in the second existing technical solution; Figure 9 This is a schematic diagram of the steel plate butt joint tack welding and arc striking and extinguishing plate installation in the second existing technical solution; Figure 10 This is a schematic diagram of installing the FGB liner in the second prior art solution; Figure 11 This is a schematic diagram of laying iron powder in the second existing technical solution; Figure 12 This is a schematic diagram of FGB single-sided submerged arc automatic welding in the second existing technical solution; Figure 13 This is a schematic diagram of steel plate assembly in a single-sided submerged arc automatic welding method provided by an embodiment of the present invention; Figure 14 This is a schematic diagram of tack welding of steel plate butt joints and installation of arc striking and extinguishing plates in a single-sided submerged arc automatic welding method provided by an embodiment of the present invention; Figure 15 This is a schematic diagram of installing an FGB gasket in a single-sided submerged arc automatic welding method provided by an embodiment of the present invention (the third arc striking and extinguishing plate is hidden); Figure 16 This is a schematic diagram of locally laying iron powder in a single-sided submerged arc automatic welding method provided by an embodiment of the present invention; Figure 17 This is a schematic diagram of FGB single-sided submerged arc automatic welding in a single-sided submerged arc automatic welding method provided by an embodiment of the present invention; Figure 18 It is a schematic diagram of the FGB single-sided submerged arc automatic welding effect in a single-sided submerged arc automatic welding method provided by an embodiment of the present invention.

[0020] Markings in the figure: First steel plate 100; first steel plate butt joint 101; first large gap area 102; first tack weld 103; first arc ignition plate 104; large gap additional weld 105; front weld 106; area with weld bead and slag inclusion defects 107; back weld 108; Second steel plate 200; groove 201; second steel plate butt joint 202; second tack weld 203; second arc ignition plate 204; first FGB gasket 205; first welding iron powder 206; first weld 207; The third steel plate 300 ; the third steel plate joint 301 ; the second large gap area 302 ; the third tack weld 303 ; the third arc striking and extinguishing plate 304 ; the second FGB gasket 306 ; the second welding iron powder 307 ; and the second weld 308 . DETAILED DESCRIPTION

[0021] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0022] In the description of the present invention, it should be understood that the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. It should be understood that the terms "first", "second", etc. are used in the present invention to describe various information, but such information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of the present invention, "first" information may also be referred to as "second" information, and similarly, "second" information may also be referred to as "first" information.

[0023] See also Figures 13 to 18 The preferred embodiment of the present invention provides a single-sided submerged arc automatic welding method, which includes the following steps: Step S1: Steel plate assembly: Figure 13 As shown, a plurality of third steel plates 300 are provided and smoothly assembled together. A third steel plate joint 301 is formed between two adjacent third steel plates 300. The third steel plate joint 301 includes a second large gap region 302 and a small gap region. In this embodiment, the gap in the second large gap region 302 is greater than 1.5 mm.

[0024] Step S2: Positioning the steel plate joints and installing the arc-ignition plate: Figure 14 As shown, the third steel plate butt joint 301 is tack welded, and third arc-igniting plates 304 are fixed at both ends of the third steel plate butt joint 301 in the extending direction. In this step, after the third steel plate butt joint 301 is tack welded, the welding slag on the third tack weld 303 is removed; the tack welding method is preferably manual arc welding or semi-automatic CO2 gas shielded welding.

[0025] Step S3: Install FGB gasket: Figure 15 As shown, a second FGB gasket 306 is installed and fixed on the reverse side of the third steel plate butt joint 301, with the center line of the second FGB gasket 306 corresponding to the center line of the third steel plate butt joint 301. In this step, the second FGB gasket 306 is tightly attached to the third steel plate 300 by self-adhesive glue.

[0026] Step S4: Locally lay iron powder: Figure 16 As shown, the second welding iron powder 307 is partially laid in the second large gap area 302 , and the second welding iron powder 307 fills the second large gap area 302 and is flush with the surface of the third steel plate 300 .

[0027] Step S5: Perform FGB single-sided submerged arc automatic welding: Figure 17 As shown, pulse arc submerged arc automatic welding equipment is used to perform FGB single-sided submerged arc automatic welding on the front side of the third steel plate butt joint 301. The pulse arc submerged arc automatic welding equipment alternately outputs peak current and base current, and completes the welding construction of the third steel plate butt joint 301 through a single-sided welding and double-sided forming welding process, and maintains a constant welding speed during the welding process.

[0028] Step S6: Remove welding slag and FGB pad: Figure 18 As shown, after welding is completed, the welding slag on the front side of the second weld 308 formed by the FGB single-sided submerged arc automatic welding in step S5 and the second FGB liner 306 on the back side are removed to complete the welding construction of the entire second weld 308.

[0029] It should be noted that in step S5, the pulsed submerged arc automatic welding equipment is used to alternately output the peak current and the base current. The peak current and base current, the peak welding voltage and the base voltage, the peak current and base current dwell time, the welding speed and other welding parameters can be flexibly adjusted according to the thickness of the third steel plate 300 to be welded, and the welding wire feed speed is automatically matched with the welding current. When in the peak welding current range, a large current (i.e., fast wire feed speed) and a small voltage (i.e., relative to the conventional standard matching voltage) are set. The large current welding arc fully melts the thickness direction of the third steel plate butt joint 301. The small voltage reduces the welding arc diameter, improves the welding arc constraint (i.e., indirectly increases the penetration depth of the welding pool, i.e., the penetration depth), and at the same time reduces the welding pool width (i.e., the accumulation height of the molten wire metal increases); when in the base value welding current range, a small current (i.e., slow wire feed speed) and a large voltage (i.e., relative to the conventional standard matching voltage) are set. The small current welding arc maintains the welding arc continuously, reducing Low weld penetration prevents excessive weld penetration, which can lead to excessive weld formation on the reverse side, weld numbness, or even burn-through. This effectively reduces welding heat input, reduces wire feed speed, and reduces wire melt. High voltage increases the welding arc diameter, reducing arc constraint (indirectly reducing the depth of penetration, or penetration, of the weld pool). It also increases the weld pool width (i.e., reheating the excess weld pool metal at the peak stage, increasing the weld pool width during small wire feeds. This increases the weld surface width formed after the liquid metal pool solidifies, reduces the residual height, and creates a smooth transition between the weld edge and the steel plate, i.e., the weld toe area, where the weld edge contacts the steel plate. This improves the formation of the second weld 308). This shows that the rapid alternating switching between peak current and base current ensures full penetration of the third steel plate butt joint 301 and excellent formation on both the front and back sides.

[0030] The single-sided submerged arc automatic welding method of the present invention has the following advantages: 1. Single-sided welding: (1) No lifting equipment is required to turn over, which occupies less lifting equipment resources; (2) Only one pre-welding preparation (such as drawing lines, laying rails, installing welding trolleys, preparing welding wires and flux, etc.) and post-welding recovery work are required, and the preparation and finishing workload is small; (3) The welding time is short and the welding efficiency is high; (4) During the welding process, the shape of the second weld 308 in the thickness direction of the third steel plate butt joint 301 is nearly symmetrical, with small differences. The cooling shrinkage of the second weld 308 on the front and back sides of the third steel plate 300 is small, and the angular deformation of the two sides of the second weld 308 is small, and the workload and difficulty of post-weld leveling are small; Second, the second largest gap area 302 does not require pre-welding: construction efficiency is high, and welding defects and defect treatment work are avoided during pre-welding; 3. The reverse side of the third steel plate butt joint 301 is supported by a second FGB liner 306, and the second largest gap region 302 is filled with second welding iron powder 307. During submerged arc automatic welding, the second largest gap region 302 is less likely to produce weld bumps or burn-through, and the second weld seam 308 is well formed, thus avoiding welding defects and related processing work. 4. The third steel plate 300 does not need to be pre-grooved: (1) There are fewer construction steps and the construction efficiency is high; (2) The third steel plate 300 is prevented from being deformed during the thermal cutting process, which reduces the difficulty of subsequent panel assembly and leveling construction; (3) The cross-sectional area of the third steel plate joint 301 that needs to be welded is small, which consumes less welding materials, has a fast welding speed, a short welding time, and consumes less electricity; (4) The cross-sectional area of the third steel plate joint 301 that needs to be welded is small, which consumes less welding materials, has a fast welding speed, and a low welding heat input (i.e., welding current × welding voltage) (5) The third steel plate butt joint 301 after the third steel plate 300 is assembled has an I-shaped cross-sectional shape, and the cross-sectional shape of the second weld 308 formed after FGB submerged arc automatic welding is also close to the I-shaped shape. The cooling shrinkage of the second weld 308 on both sides of the third steel plate 300 is nearly symmetrical, and the angular deformation of the second weld 308 on both sides is small. 5. It is possible to flexibly choose whether to lay the second welding iron powder 307 according to the size of the assembly gap of the third steel plate butt joint 301 (an error in the assembly gap of the third steel plate 300 is a normal phenomenon in actual production). The welding process is stable, the second weld 308 is formed uniformly, and there is no need to adjust the welding parameters due to changes in the size of the assembly gap of the third steel plate 300 during the welding process. The welding operation is simple, and the assembly gap of the third steel plate 300 has little effect on the welding process and the formation of the second weld 308. The welding method has strong adaptability to the assembly gap of the third steel plate 300.

[0031] It can be seen that the present invention can simplify the splicing welding construction process of the third steel plate butt joint 301, realize the grooveless single-sided welding and double-sided forming welding construction of the butt joint of thinner steel plates (10 mm and below in thickness), improve the adaptability of submerged arc welding to the gap between the third steel plate 300 splices, improve its welding quality and welding efficiency, reduce the welding deformation and welding energy consumption of the submerged arc automatic welding of the third steel plate 300 splices, and at the same time reduce the consumption of welding materials, saving comprehensive construction costs.

[0032] Exemplarily, in step S5, the diameter of the welding wire used for the FGB method single-sided submerged arc automatic welding is preferably 4.0 mm, the dry extension length of the welding wire is preferably 20~25 mm, the peak current of the pulse arc submerged arc automatic welding equipment is preferably 700~800 A, the peak voltage is preferably 28~29 V, and the peak time is preferably 0.5~1 s; the base current of the pulse arc submerged arc automatic welding equipment is preferably 500~550 A, the base voltage is preferably 28~29 V, and the base time is preferably 0.5~1 s; the welding speed is preferably 27~30 m / h.

[0033] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integral connection; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0034] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A single-sided submerged arc automatic welding method, characterized in that: The steps include: Step S1: Steel plate assembly: providing a plurality of third steel plates, and assembling the third steel plates flatly together, forming a third steel plate butt joint between two adjacent third steel plates, wherein the third steel plate butt joint includes a second largest gap area and a small gap area; Step S2: Positioning the steel plate butt joint and installing the arc striking and extinguishing plates: performing tack welding on the third steel plate butt joint, and installing and fixing the third arc striking and extinguishing plates at both ends of the third steel plate butt joint in the extending direction; Step S3: Installing the FGB gasket: Installing and fixing the second FGB gasket on the reverse side of the butt joint of the third steel plate, wherein the center line of the second FGB gasket corresponds to the center line of the butt joint of the third steel plate; Step S4: Locally laying iron powder: locally laying second welding iron powder in the second large gap area, wherein the second welding iron powder fills the second large gap area and is flush with the surface of the third steel plate; Step S5: performing FGB single-sided submerged arc automatic welding: performing FGB single-sided submerged arc automatic welding on the front side of the butt joint of the third steel plate using a pulsed arc submerged arc automatic welding device, wherein the pulsed arc submerged arc automatic welding device alternately outputs peak current and base current to complete the welding construction of the butt joint of the third steel plate through a single-sided welding and double-sided forming welding process, and maintaining a constant welding speed during the welding process; Step S6: Removing welding slag and FGB liner: After welding is completed, the welding slag on the front side of the second weld formed by the FGB single-sided submerged arc automatic welding in step S5 and the second FGB liner on the back side are removed to complete the welding construction of the entire second weld.

2. The single-sided submerged arc automatic welding method according to claim 1, characterized in that: In the step S2, after the third steel plate butt joint is tack welded, welding slag on the third tack weld is removed.

3. The single-sided submerged arc automatic welding method according to claim 1, characterized in that: In step S2, the tack welding process is performed by manual arc welding or semi-automatic CO2 gas shielded welding.

4. The single-sided submerged arc automatic welding method according to claim 1, characterized in that: In step S3, the second FGB gasket and the third steel plate are tightly bonded by self-adhesive glue.

5. The single-sided submerged arc automatic welding method according to claim 1, characterized in that: The gap in the second largest gap area is greater than 1.5 mm.

6. The single-sided submerged arc automatic welding method according to claim 1, characterized in that: In step S5, the diameter of the welding wire used in the FGB single-sided submerged arc automatic welding is 4.0 mm, and the dry extension length of the welding wire is 20-25 mm.

7. The single-sided submerged arc automatic welding method according to claim 1, characterized in that: In step S5, the peak current of the pulse arc submerged arc automatic welding equipment is 700-800 A, the peak voltage is 28-29 V, and the peak time is 0.5-1 s.

8. The single-sided submerged arc automatic welding method according to claim 1, characterized in that: In step S5, the base current of the pulse arc submerged arc automatic welding equipment is 500-550A, the base voltage is 28-29V, and the base time is 0.5-1s.

9. The single-sided submerged arc automatic welding method according to claim 1, characterized in that: In step S5, the welding speed of the pulse arc submerged arc automatic welding equipment is 27-30 m / h.

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