Thick plate high heat input welding method and thick plate welding test plate

Abstract

The invention discloses a thick plate high heat input welding method and a thick plate welding test plate, and belongs to the technical field of ocean engineering equipment manufacturing. The thick plate high heat input welding method comprises the following steps that S100, a first plate and a second plate are assembled in pairs, a liner is laid on the back face, an assembly is formed, and a first groove face of the first plate and a second groove face of the second plate form a double-side groove of a butt joint groove weld zone; a first plating layer containing nickel is arranged on the first groove surface, and a second plating layer containing nickel is arranged on the second groove surface; and S200, the assembly is vertically arranged, high heat input vertical gas-electric welding is conducted on the butt joint groove welding seam area, and the first plate and the second plate are connected to form a thick plate welding test plate. According to the thick plate high heat input welding method and the thick plate welding test plate, the strength, low-temperature toughness and fatigue resistance of a welding joint are improved.

Description

Technical Field

[0001] This invention relates to the field of marine engineering equipment manufacturing technology, and in particular to a method for welding thick plates with high heat input and a test plate for welding thick plates. Background Technology

[0002] In marine engineering equipment manufacturing, high-energy vertical gas-electric high-efficiency welding employs a high-energy-density arc and forced forming process, using special welding wire with CO2 or mixed gas for protection. It achieves precise control of the molten pool through double-sided forming and dynamic cooling system. The weld front is equipped with a circulating water-cooled copper slider, and the back uses a high-temperature resistant ceramic pad or a fixed water-cooled copper pad. The welding heat input can reach 100kJ / cm~700kJ / cm, which is significantly more efficient than traditional welding methods such as manual welding or CO2 semi-automatic welding. However, due to its extremely large welding heat input, the quality and performance of the welded joint are often difficult to guarantee.

[0003] Vertical gas-electric welding typically uses a heat input of over 200 kJ / cm. Such a large heat input causes the temperature of the heat-affected zone of the weld joint to reach up to 1400℃. The weld joint remains in the high-temperature zone for a long time, which induces coarsening of austenite grains in the coarse-grained zone. After cooling, it forms coarse grain boundary ferrite, Widmanstätten, and upper bainite, which are low-impact toughness structures, reducing the strength, toughness, and fatigue resistance of the weld joint. Summary of the Invention

[0004] The purpose of this invention is to provide a method for welding thick plates with high heat input and a test plate for welding thick plates, thereby improving the strength, low-temperature toughness and fatigue resistance of the welded joint.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] A method for welding thick plates with high heat input includes:

[0007] S100. Assemble the first plate and the second plate together and lay a backing on the back to form an assembly. The first bevel surface of the first plate and the second bevel surface of the second plate form a double bevel of the butt weld area. The first bevel surface is provided with a first nickel plating layer and the second bevel surface is provided with a second nickel plating layer.

[0008] S200. The assembly is set vertically, and high-input vertical gas-electric welding is performed on the butt joint weld area to connect the first plate and the second plate to form a thick plate welding test plate.

[0009] In some embodiments, before step S100, which involves providing a first nickel-containing plating layer on the first bevel surface and a second nickel-containing plating layer on the second bevel surface, the following steps are included:

[0010] S110. The first bevel surface is machined on the side of the first plate used for welding, and the second bevel surface is machined on the side of the second plate used for welding.

[0011] In some embodiments, step S100 includes:

[0012] S120. Nickel plating is performed on the first bevel surface using nickel-containing welding material to form the first plating layer, and nickel plating is performed on the second bevel surface to form the second plating layer.

[0013] S130. Assemble the first plate and the second plate together.

[0014] In some embodiments, step S100 further includes:

[0015] Grind the first plating layer so that its surface is parallel to the surface of the first bevel before nickel plating; grind the second plating layer so that its surface is parallel to the surface of the second bevel before nickel plating.

[0016] In some embodiments, the nickel content of the first coating is 1%-40%, and the nickel content of the second coating is 1%-40%.

[0017] In some embodiments, the thickness of the first coating is 5mm-10mm, and the thickness of the second coating is 5mm-10mm.

[0018] In some embodiments, the root gap of the butt joint weld zone ranges from 3mm to 8mm, and the bevel angle ranges from 20° to 40°.

[0019] In some embodiments, the angle range of the first bevel surface is 10°-20°, and the angle range of the second bevel surface is 10°-20°.

[0020] In some embodiments, the thickness of the first plate is greater than or equal to 30 mm, and the thickness of the second plate is greater than or equal to 30 mm.

[0021] A thick plate welding test plate is welded using the thick plate high heat input welding method as described in any of the preceding claims.

[0022] The beneficial effects of this invention are:

[0023] This invention provides a method for high heat input welding of thick plates and a test plate for welding thick plates. During the welding operation, the welding torch moves along a preset welding path, and the electric arc at its end generates high temperature to melt the welding wire, forming a weld pool with a certain volume and fluidity. As the welding torch continues to move forward, the welding wire in front of the arc continuously melts and replenishes the weld pool, while the molten pool metal behind it gradually cools and solidifies under the action of the temperature gradient, forming a continuous weld deposited metal. The weld deposited metal combines with the first and second coatings on both sides, so that the weld deposited metal, the first coating, the second coating, the heat-affected zone of the first plate and the second plate form a welded joint. By applying a nickel-containing first plating layer to the first bevel surface and a nickel-containing second plating layer to the second bevel surface in the butt weld zone, a transition layer with good low-temperature impact toughness is formed between the first and second plating layers. This effectively isolates the molten pool temperature, prevents coarse microstructure and local softening in the heat-affected zone (HAZ), and improves the strength and low-temperature toughness of the welded joint. Under high-temperature conditions, the nickel element in the first plating layer penetrates into the HAZ of the first plate, while the nickel element in the second plating layer penetrates into the HAZ of the second plate, inhibiting grain growth in the HAZ, refining the grain structure, and generating fine equiaxed microstructure. This effectively improves the strength, low-temperature toughness, and fatigue resistance of the welded joint, thereby effectively mitigating the performance degradation problem of thick plate high heat input welded joints and ensuring reliable and stable welded joint quality. Thick plate welding test plates were welded using the aforementioned thick plate high heat input welding method, resulting in welded joints with improved strength, low-temperature toughness, and fatigue resistance, ensuring reliable and stable welded joint quality. Attached Figure Description

[0024] Figure 1 This is a flowchart of a high heat input welding method for thick plates provided by a specific embodiment of the present invention;

[0025] Figure 2 This is a flowchart of another thick plate high heat input welding method provided by a specific embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of the first and second plates provided in a specific embodiment of the present invention;

[0027] Figure 4 This is a schematic diagram of the first and second coating layers provided in a specific embodiment of the present invention;

[0028] Figure 5 This is a schematic diagram of the assembly provided in a specific embodiment of the present invention;

[0029] Figure 6 This is a side view of high-energy vertical gas-electric welding provided in a specific embodiment of the present invention;

[0030] Figure 7This is a top view of high-energy vertical gas-electric welding provided in a specific embodiment of the present invention;

[0031] Figure 8 This is a schematic diagram of a thick plate welding test plate formed after welding, provided by a specific embodiment of the present invention.

[0032] In the picture:

[0033] 100, First plate material; 110, First bevel face; 120, First coating; 200, Second plate material; 210, Second bevel face; 220, Second coating; 300, Gasket; 400, Butt joint weld zone; 500, Assembly; 600, Welding torch; 700, Weld pool; 800, Water-cooled copper slider; 910, Weld deposited metal; 920, Heat-affected zone of base material. Detailed Implementation

[0034] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0036] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0037] like Figures 1-8 As shown, this embodiment provides a method for welding thick plates with high heat input, including the following steps:

[0038] S100, the first plate 100 and the second plate 200 are assembled together and a backing 300 is laid on the back to form an assembly 500. The first bevel surface 110 of the first plate 100 and the second bevel surface 210 of the second plate 200 form a double bevel of the butt weld area 400. The first bevel surface 110 is provided with a first nickel plating layer 120 and the second bevel surface 210 is provided with a second nickel plating layer 220.

[0039] S200, set the assembly 500 vertically, and perform high-energy vertical gas-electric welding on the butt joint weld zone 400 to connect the first plate 100 and the second plate 200 to form a thick plate welding test plate.

[0040] During welding, the welding torch 600 moves along a preset welding path, and the electric arc at its end generates high temperature to melt the welding wire, forming a weld pool 700 with a certain volume and fluidity. As the welding torch 600 continues to move forward, the welding wire in front of the arc continuously melts and replenishes the weld pool, while the molten pool metal behind it gradually cools and solidifies under the action of the temperature gradient, forming a continuous weld deposited metal 910. The weld deposited metal 910 combines with the first coating 120 and the second coating 220 on both sides, so that the weld deposited metal 910, the first coating 120, the second coating 220, and the heat-affected zone 920 of the base material of the first plate 100 and the second plate 200 form a welded joint. By setting a nickel-containing first plating layer 120 on the first bevel surface 110 of the butt weld zone 400 and a nickel-containing second plating layer 220 on the second bevel surface 210, the first plating layer 120 and the second plating layer 220 form a transition layer with good low-temperature impact toughness, effectively isolating the molten pool temperature, avoiding coarse microstructure and local softening in the heat-affected zone, and improving the strength and low-temperature toughness of the welded joint. Under high-temperature conditions, the nickel element in the first plating layer 120 penetrates into the heat-affected zone 920 of the base material of the first plate 100, and the nickel element in the second plating layer 220 penetrates into the heat-affected zone 920 of the base material of the second plate 200, inhibiting grain growth in the heat-affected zone 920 of the base material, refining the microstructure grains, and generating fine equiaxed microstructure, the strength, low-temperature toughness and fatigue resistance of the welded joint are effectively improved. This effectively improves the performance degradation problem of thick plate high heat input welded joints, ensuring reliable quality and stable performance of the welded joint.

[0041] The high heat input welding method for thick plates is suitable for automated and efficient welding of large marine engineering equipment such as thick plates for crack arresting steel in large container ships and thick-walled structures for offshore wind turbine jackets, effectively improving the performance degradation problem of high heat input welded joints. Optionally, the thickness of the first plate 100 is B1, where B1 is greater than or equal to 30mm, and the thickness of the second plate 200 is B2, where B2 is greater than or equal to 30mm. The thicknesses of the first plate 100 and the second plate 200 can be the same or different. The high heat input welding method for thick plates can achieve one-pass welding of 30mm-80mm thick marine engineering high-strength steel plates, improving the quality and performance of high-efficiency welding of low-temperature high-strength steel.

[0042] In one embodiment, two high-strength steel plates are taken, namely the first plate 100 and the second plate 200, both with a thickness of 30mm. Step S100 further includes:

[0043] S110, a first bevel surface 110 is machined on the side of the first plate 100 used for welding, and a second bevel surface 210 is machined on the side of the second plate 200 used for welding.

[0044] S120. Nickel plating is performed on the first bevel surface 110 to form a first plating layer 120, and nickel plating is performed on the second bevel surface 210 to form a second plating layer 220.

[0045] S130, Assemble the first plate 100 and the second plate 200 together.

[0046] like Figure 3 As shown, in step S100, before the first nickel-containing first plating layer 120 is applied to the first bevel surface 110 and the second nickel-containing second plating layer 220 is applied to the second bevel surface 210, the first bevel surface 110 is processed on the welding side of the first plate 100, and the second bevel surface 210 is processed on the welding side of the second plate 200. The first bevel surface 110 and the second bevel surface 210 can be set according to requirements, and thus the bevel angle of the butt weld area 400 can be set according to requirements. Optionally, the angle of the first bevel surface 110 is A1, with a range of 10°-20°, and the angle of the second bevel surface 210 is A2, with a range of 10°-20°. The angles of the first bevel surface 110 and the second bevel surface 210 can be the same or different, and can be set according to requirements, which will not be elaborated further.

[0047] like Figure 4 and Figure 5 As shown, the first plating layer 120 and the second plating layer 220 are formed by welding before the first plate 100 and the second plate 200 are assembled, which facilitates nickel plating welding, makes the operation convenient, and achieves efficient welding.

[0048] Optionally, step S100 further includes: grinding the first plating layer 120 so that the surface of the first plating layer 120 is parallel to the surface of the first bevel surface 110 before nickel plating; grinding the second plating layer 220 so that the surface of the second plating layer 220 is parallel to the surface of the second bevel surface 210 before nickel plating, thereby facilitating control of the thickness of the first plating layer 120 and the second plating layer 220. Figure 5 As shown, optionally, the thickness of the first plating layer 120 is C1, and the range of C1 is 5mm-10mm. The thickness of the second plating layer 220 is C2, and the range of C2 is 5mm-10mm. The thickness of the first plating layer 120 and the thickness of the second plating layer 220 can be the same or different, and can be set according to the requirements, which will not be elaborated further.

[0049] The first plating layer 120 has a nickel content of 1%-40%, and the second plating layer 220 has a nickel content of 1%-40%. Specifically, in step S120, when welding the first bevel surface 110 and the second bevel surface 210, welding materials with a nickel content of 1%-40% are selected. The nickel content is selected according to the amount of welding heat input and is not limited. Optionally, recommended welding material chemical compositions are shown in Table 1.

[0050]

[0051] In step S130, when the first plate 100 and the second plate 200 are assembled together, the root gap of the butt joint weld zone 400 is L, which ranges from 3mm to 8mm, and the bevel angle is A, which ranges from 20° to 40°. As the set welding heat input increases, the root assembly gap and the bevel angle increase accordingly.

[0052] Optionally, the backing 300 is a ceramic backing or a water-cooled copper backing. The backing 300 is bonded to the root side of the butt joint weld zone 400 of the first plate 100 and the second plate 200. The backing 300 is used to constrain the molten pool, prevent burn-through, and ensure the formation of the back side of the butt joint weld zone 400. It can be removed after welding. Taking a ceramic backing as an example, on the one hand, it can accurately support the molten pool at the root of the butt joint weld zone 400. The ceramic material is resistant to high temperatures and is not easily damaged under the high temperature of the electric arc, which can effectively prevent root burn-through, especially solving the lack of fusion defects that are prone to occur at the lower end of the root weld. On the other hand, its low thermal conductivity and slow cooling rate can provide a stable solidification environment for the root molten pool, reduce defects such as porosity and slag inclusions, and ensure the metallurgical bonding quality of the root weld.

[0053] Optionally, a water-cooled copper slider 800 is provided on the surface of the first plate 100 and the second plate 200 on the opposite side of the butt joint weld area 400, which is opposite to the backing 300. This is a combination of a copper slider and a water-cooling system, as can be found in existing technologies. Copper has excellent thermal conductivity, and when combined with a water-cooling system, it can quickly remove a large amount of heat from the weld surface, accelerate the solidification of the weld surface, and make the weld surface smooth and full, reducing the amount of post-weld grinding work. At the same time, forced cooling can refine the weld surface grains, improve the hardness and strength of the weld surface, and the copper slider is not metallurgically bonded to the deposited metal, making subsequent removal convenient and preventing residual impurities from affecting the weld surface quality.

[0054] By simultaneously using a backing 300 and a water-cooled copper slider 800, the backing 300 stabilizes the weld root, while the water-cooled copper slider 800 constrains the weld surface, jointly limiting the flow range of molten metal and preventing burn-through or weld deformation. This allows for qualified weld formation on both sides in a single welding operation, significantly reducing the number of steps. This combination is suitable for welding scenarios with high heat input. The forced cooling of the water-cooled copper slider 800 prevents overheating and grain coarsening of the weld under high heat input, while the ceramic backing ensures stable root penetration. This achieves efficient one-time forming of thick steel plates while ensuring that the weld's tensile strength, hardness, and other mechanical properties meet industry standards, significantly improving welding efficiency.

[0055] like Figure 6 and Figure 7 As shown, in step S200, the assembly 500 is placed vertically and fixed, and then high-energy vertical gas electric welding is performed. Recommended welding parameters are shown in Table 2.

[0056]

[0057] This embodiment also provides a thick plate welding test plate, which is welded using the thick plate high heat input welding method described above. The welded joint formed by the weld deposited metal 910, the first coating 120, the second coating 220, the heat affected zone 920 of the base material of the first plate 100 and the second plate 200 has improved strength, low temperature toughness and fatigue resistance, and can ensure that the welded joint has reliable quality and stable performance.

[0058] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for welding thick plates with high heat input, characterized in that, include: S100. Assemble the first plate (100) and the second plate (200) and lay a backing (300) on the back to form an assembly (500). The first bevel surface (110) of the first plate (100) and the second bevel surface (210) of the second plate (200) form a double bevel of the double-sided butt weld area (400). The first bevel surface (110) is provided with a first nickel plating layer (120), and the second bevel surface (210) is provided with a second nickel plating layer (220). S200. The assembly (500) is set vertically, and high-energy vertical gas electric welding is performed on the butt joint groove weld area (400) to connect the first plate (100) and the second plate (200) to form a thick plate welding test plate.

2. The method for welding thick plates with high heat input according to claim 1, characterized in that, In step S100, before a first nickel-containing plating layer (120) is formed on the first bevel surface (110) and a second nickel-containing plating layer (220) is formed on the second bevel surface (210), the following steps are included: S110. The first bevel surface (110) is machined on the side of the first plate (100) used for welding, and the second bevel surface (210) is machined on the side of the second plate (200) used for welding.

3. The method for welding thick plates with high heat input according to claim 1, characterized in that, Step S100 includes: S120. Nickel plating is performed on the first bevel surface (110) using nickel-containing welding material to form the first plating layer (120), and nickel plating is performed on the second bevel surface (210) to form the second plating layer (220). S130. Assemble the first plate (100) and the second plate (200).

4. The method for welding thick plates with high heat input according to claim 3, characterized in that, Step S100 also includes: Polish the first plating layer (120) so that the surface of the first plating layer (120) is parallel to the surface of the first bevel surface (110) before nickel plating; polish the second plating layer (220) so that the surface of the second plating layer (220) is parallel to the surface of the second bevel surface (210) before nickel plating.

5. The method for welding thick plates with high heat input according to claim 1, characterized in that, The first plating layer (120) has a nickel content of 1%-40%, and the second plating layer (220) has a nickel content of 1%-40%.

6. The method for welding thick plates with high heat input according to claim 1, characterized in that, The thickness of the first coating (120) is 5mm-10mm, and the thickness of the second coating (220) is 5mm-10mm.

7. The method for welding thick plates with high heat input according to claim 1, characterized in that, The root gap of the butt joint groove weld zone (400) ranges from 3mm to 8mm, and the groove angle ranges from 20° to 40°.

8. The method for welding thick plates with high heat input according to claim 1, characterized in that, The angle range of the first bevel surface (110) is 10°-20°, and the angle range of the second bevel surface (210) is 10°-20°.

9. The method for welding thick plates with high heat input according to any one of claims 1-8, characterized in that, The thickness of the first plate (100) is greater than or equal to 30 mm, and the thickness of the second plate (200) is greater than or equal to 30 mm.

10. A thick plate welding test plate, characterized in that, Welding is performed using the high heat input welding method for thick plates as described in any one of claims 1-9.

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