A method of welding a composite panel

Abstract

The application discloses a composite plate welding method, comprising the following steps: groove processing; welding a base layer by adopting a submerged arc welding filling method; adopting hot wire TIG welding to build up a transition layer on the surface of the base layer weld; and adopting hot wire TIG welding to complete a composite layer filling and a cover surface. Thus, the base layer is welded by adopting the submerged arc welding, the protection characteristic of the flux is used to isolate air, and the high deposition advantage of the continuous wire feeding is used, so that the fast and continuous welding of the base layer weld is realized, and the problems of frequent interruption and low efficiency in the traditional process welding are solved; the transition layer and the composite layer are welded by adopting the hot wire TIG welding, the characteristic that the hot wire preheating reduces the arc heat load is used, the molten pool heat input and the base material dilution rate are accurately controlled, the component dilution of the base layer carbon steel element to the stainless steel composite layer is avoided, and the corrosion resistance of the composite layer is ensured.

Description

Technical Field

[0001] This application belongs to the field of composite material welding technology, and particularly relates to a composite plate welding method. Background Technology

[0002] Stainless steel composite plates combine the excellent mechanical strength and processing performance of carbon steel base layers with the corrosion resistance of stainless steel cladding layers, significantly reducing the cost of precious metal consumables. They are widely used in the manufacturing of large industrial equipment such as hot blast furnace shells. Welding these composite plates requires ensuring both the structural strength of the base layer and the corrosion resistance of the cladding layer, placing stringent demands on the matching of welding processes for the base layer, transition layer, and cladding layer. Summary of the Invention

[0003] This application aims to address, at least to some extent, the technical problems of low welding efficiency, poor weld quality stability, difficulty in controlling the dilution rate of the base material in the transition layer leading to cold cracking and decreased corrosion resistance of the cladding layer, and high overall welding costs in composite plates. To this end, this application provides a welding method for composite plates.

[0004] The present application provides a composite plate welding method, which includes the following steps: S1. Beveling; S2. Welding the base layer using submerged arc welding; S3. Depositing a transition layer on the surface of the base layer weld using hot wire TIG welding; S4. Completing the cladding and cover layer using hot wire TIG welding.

[0005] Therefore, submerged arc welding is used for the base layer, utilizing the protective properties of flux that isolate it from air and the high deposition rate of continuous wire feeding to achieve rapid and continuous welding of the base layer weld, solving the problems of frequent interruptions and low efficiency in traditional welding processes. Hot-wire TIG welding is used for the transition layer and cladding layer, utilizing the characteristic of hot wire preheating to reduce the arc heat load, precisely controlling the heat input of the molten pool and the dilution rate of the base material, avoiding the dilution of the stainless steel cladding layer by the carbon steel elements in the base layer, and ensuring the corrosion resistance of the cladding layer. The base layer, which bears the structural load, is welded first, then the transition layer provides a double buffer of composition and welding stress, and finally the cladding layer, which bears the corrosion resistance, is welded. The structural connection between processes avoids mutual interference between different welding processes. At the same time, through the complementary advantages of different processes, both the structural strength requirements of the base layer and the corrosion resistance requirements of the cladding layer are met, fully adapting to the dual working conditions of pressure bearing and corrosion resistance of the hot blast furnace shell.

[0006] In one possible implementation, the beveling process includes: machining a first bevel with an angle of 40°-45° on one of the composite plates to be welded, and machining a second bevel with an angle of 10°-15° on the other plate. Both the first and second bevels are symmetrical K-type bevels. Oil and oxide scale are cleaned from the bevels and within 20mm on both sides until a metallic luster is exposed. Thus, the angled structure of the first and second bevels achieves a synergistic effect between weld accessibility and penetration control. The large angle of the first bevel (40°-45°) provides ample operating space for the submerged arc welding torch, ensuring that the torch can penetrate deep into the root of the bevel, achieving full penetration welding of the base layer and avoiding root incomplete fusion defects. Simultaneously, the large angle bevel disperses the welding heat input, reducing welding stress during base layer welding and preventing peeling defects at the interface between the base layer and the cladding layer of the composite plate. The second bevel uses a small angle bevel of 10°-15°, which can strictly limit the bevel cross-sectional area during cladding welding, reduce the amount of filler metal in cladding welding, and at the same time reduce the range of the welding heat-affected zone, reduce the heat input during cladding welding, avoid carbide precipitation caused by overheating of the stainless steel cladding, and ensure the corrosion resistance of the cladding. At the same time, the small angle bevel can limit the penetration depth during cladding welding, prevent the welding arc from melting the base carbon steel, and reduce the dilution of carbon steel elements on the stainless steel cladding.

[0007] In one possible implementation, the submerged arc welding method for filling the base layer includes: a current intensity of 300A-350A, an arc voltage of 30V-34V, a welding speed of 25cm / min-30cm / min, a flux layer thickness of 8mm-12mm, an interpass temperature controlled at 150℃-200℃, and welding to a distance of 3mm-5mm from the cladding layer interface. This achieves a synergy between the deposition efficiency and the quality of the base layer weld: the high current of 300A-350A, matched with the arc voltage of 30V-34V, forms a stable welding arc, increasing the deposition rate of the welding wire and enabling efficient continuous welding of the base layer weld; the welding speed of 25cm / min-30cm / min matches the deposition rate, controlling the weld penetration and width, and avoiding common defects in horizontal weld positions such as weld run-down and undercut. A flux thickness of 8mm-12mm creates a stable protective barrier: the flux completely covers the welding arc and the molten pool, isolating harmful gases such as oxygen and nitrogen from the air and preventing oxidation and nitriding of the molten pool metal. Simultaneously, the slag formed after the flux melts refines the molten pool metal, removing impurities and improving the metallurgical quality of the weld. Within this thickness range, the flux completely covers the arc, preventing arc radiation and spatter, while avoiding poor weld formation and porosity defects due to excessive flux thickness. Interpass temperature control of 150℃-200℃ matches the welding characteristics of the base carbon steel, preventing welding defects: an interpass temperature not lower than 150℃ prevents rapid cooling of the weld metal, preventing the formation of hardened martensite and reducing the risk of cold cracking; an interpass temperature not higher than 200℃ avoids excessive welding heat input leading to increased residual stress and prevents heat transfer through the composite interface to the cladding layer, preventing overheating and sensitization of the cladding stainless steel. The structural design of stopping welding at 3mm-5mm from the cladding layer interface forms a buffer isolation layer between the base weld and the cladding layer: the reserved 3mm-5mm carbon steel layer can prevent the high current arc of the base submerged arc welding from melting the composite interface, prevent the carbon steel elements of the base layer from mixing into the stainless steel of the cladding layer, and at the same time reserve fusion space for subsequent transition layer welding, ensuring that the transition layer can form a good metallurgical bond with the base weld. At the same time, the penetration depth of the base layer during transition layer welding is strictly controlled to reduce the dilution rate of the base material.

[0008] In one possible implementation, hot-wire TIG welding is used to deposit a transition layer on the surface of the base weld, comprising: a current intensity of 180A-220A, an arc voltage of 12V-15V, a hot-wire current intensity of 80A-100A, a welding speed of 8cm / min-12cm / min, an interpass temperature ≤150℃, and a penetration depth controlled at 1mm-2mm. Thus, the parameters of the hot-wire current and the main welding current are coordinated to achieve synergistic control of the welding deposition efficiency and dilution rate of the transition layer. The main welding current of 180A-220A is responsible for melting the base metal to form a molten pool, ensuring the metallurgical bonding between the transition layer and the base weld; the 80A-100A hot-wire current preheats the filler wire through resistance heating, significantly reducing the arc heat required for wire melting. This allows for increased wire feeding speed and improved deposition efficiency without increasing the main arc heat input; simultaneously, the reduced main arc heat input enables precise control of the weld penetration depth, reducing the melting of the base carbon steel and lowering the base metal dilution rate. A welding speed of 8cm / min-12cm / min and an interpass temperature control of ≤150℃ enable precise control of the total welding heat input, preventing overheating of the cladding stainless steel. The welding speed is matched with the hot wire feed speed to ensure uniform weld formation and avoid defects such as incomplete fusion and weld beads. The interpass temperature of ≤150℃ allows control of the dwell time of the welding area within the sensitization temperature range of stainless steel, preventing the precipitation of chromium carbides and reducing residual welding stress to prevent delamination of the composite interface. The 1mm-2mm penetration depth control structure achieves a balance between bonding strength and dilution rate control: the 1mm-2mm penetration depth ensures sufficient metallurgical bonding between the transition layer weld and the base carbon steel, guaranteeing the weld bonding strength and avoiding defects such as incomplete fusion and delamination; at the same time, strictly controlling the penetration depth within 2mm minimizes the melting amount of the base carbon steel, keeping the base material dilution rate within 10%, preventing large amounts of iron and carbon elements from entering the transition layer weld, ensuring the alloy element content of the transition layer weld, and providing a corrosion-resistant foundation for the cladding weld.

[0009] In one possible implementation, the cladding and cover layers include: a current intensity of 160A-200A, an arc voltage of 11V-14V, a hot wire current intensity of 70A-90A, a welding speed of 10cm / min-15cm / min, an interpass temperature ≤100℃, and a reinforcement height controlled between 0mm and 1.5mm. Thus, the 160A-200A main welding current is matched with the 70A-90A hot wire current, reducing the arc heat load through hot wire preheating, significantly reducing the total welding heat input while ensuring deposition efficiency; the 10cm / min-15cm / min welding speed controls the heat input per unit length of weld, preventing overheating; and the strict control of the interpass temperature ≤100℃ completely prevents the weld area from entering the sensitization temperature range of 450℃-850℃, fundamentally inhibiting chromium carbide precipitation and ensuring the passivation capability and corrosion resistance of the cladding weld. The controlled weld reinforcement height of 0mm-1.5mm achieves a synergy between weld corrosion resistance and structural performance: Controlling the reinforcement height within 1.5mm avoids stress concentration on the weld surface, preventing fatigue cracks at the weld reinforcement height location under high temperature and pressure conditions in the hot blast furnace shell; simultaneously, a smooth weld surface ensures the uniformity of subsequent pickling and passivation treatment, forming a complete and dense passivation film, avoiding the risk of uneven passivation film and localized corrosion caused by excessive reinforcement height; a reinforcement height ≥0mm ensures the effective thickness of the weld cross-section, preventing weakening of the weld cross-section and guaranteeing the structural continuity and load-bearing capacity of the cladding weld. The argon shielding structure of hot-wire TIG welding provides a clean welding environment for cladding welds: argon, as an inert shielding gas, completely isolates harmful gases such as oxygen and nitrogen in the air, preventing easily oxidized alloying elements such as chromium and nickel in the molten pool from burning off, and ensuring the stability of the weld alloy composition; at the same time, the preheating of the hot wire ensures that the welding wire is at a uniform temperature when fed into the molten pool, the molten pool flows smoothly, the weld is aesthetically pleasing, and there are no spatter or porosity defects, thus improving the surface quality and metallurgical quality of the weld.

[0010] In one possible implementation, the submerged arc welding uses H10Mn welding wire with a diameter of 4.0 mm and HJ101 flux, and the flux is dried at 300°C for two hours; the hot wire TIG welding uses Φ1.2 mm filler wire with a composition of 385.

[0011] In one possible implementation, the composite plate is composed of a Q345R base layer and a 904L stainless steel cladding layer.

[0012] In one possible implementation, after step S2, the base weld is subjected to visual inspection and ultrasonic testing within 24 hours post-weld. This 24-hour post-weld inspection allows for timely detection of welding defects, preventing them from lingering in subsequent processes and causing quality risks. It ensures that all welding defects are detected promptly, avoiding the need to remove completed cladding and transition layer welds for rework after the transition and cladding layers are completed, which would significantly increase rework costs and the risk of project delays. In one possible implementation, a post-weld penetration test (PT) is performed after step S3. Therefore, the implementation of PT testing after the transition layer weld can promptly identify surface opening defects in the transition layer, preventing these defects from being covered by the cladding weld and leaving potential quality issues. The transition layer weld is the core structure connecting the base layer and the cladding layer. Opening defects such as cracks and pores on its surface, if not detected in time, will be covered by subsequent cladding welds, becoming internal defects. This not only reduces the weld's bonding strength but also becomes a penetration channel for corrosive media, leading to the failure of the cladding layer's corrosion resistance and even the risk of shell leakage. Completing the PT test before cladding welds can thoroughly identify surface opening defects in the transition layer, allowing for timely repairs and ensuring the surface quality and structural integrity of the transition layer weld.

[0013] In one possible implementation, after step S4, the overall weld is visually inspected, and ultrasonic and penetrant testing is performed 24 hours later. Spatter and slag on the weld surface are removed, and the cladding side undergoes pickling and passivation treatment. Thus, the combined UT+PT final inspection achieves closed-loop quality control of the entire weld process and cross-section. The cladding side pickling and passivation treatment can repair the passivation film damaged during welding, restoring and improving the corrosion resistance of the cladding weld. The combined process of post-weld cleaning and passivation treatment ensures the uniformity and stability of the passivation film. Attached Figure Description

[0014] 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.

[0015] Figure 1 This is a bevel type and welding schematic diagram provided in an embodiment of this application.

[0016] Figure label: 1-Base layer; 2-Multi-layer. Detailed Implementation

[0017] 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.

[0018] It should be noted that all directional indications in the embodiments of this 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 indication will also change accordingly. In this invention, unless otherwise explicitly specified and limited, the terms "connection" and "fixed" should be interpreted broadly. For example, "fixed" can be a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two components or the interaction relationship between two components, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances. In addition, the descriptions involving "first," "second," etc., in this invention 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. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Furthermore, the technical solutions of the various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0019] Currently, in composite plate welding operations, the base layer welding mostly uses shielded metal arc welding (SMAW) or gas shielded welding (GSAW), requiring multi-layer, multi-pass welding with strict control of interpass temperature. The welding process is frequently interrupted, making continuous and efficient operation difficult and unsuitable for large-scale production schedules. The welding of the cladding and transition layers often combines manual SMAW with conventional argon arc welding. Welding quality is significantly affected by the operator's skill level, resulting in poor weld quality consistency. Furthermore, it is impossible to accurately control the base material dilution rate, easily leading to alloy element loss, martensite formation, and defects such as cold cracking and reduced corrosion resistance. This also results in high material consumption and high labor and rework costs.

[0020] This application provides a composite plate welding method, which can at least partially solve the technical problems of low welding efficiency, poor weld quality stability, difficulty in controlling the dilution rate of the transition layer base material leading to cold cracking and decreased corrosion resistance of the cladding layer, and high overall welding cost of stainless steel composite plates.

[0021] This application is described below with reference to the accompanying drawings and specific embodiments: This application provides a composite plate welding method, including the following steps: S1. Beveling; S2. Welding the base layer 1 using submerged arc welding; S3. Depositing a transition layer on the weld surface of the base layer 1 using hot wire TIG welding; S4. Completing the filling and covering of the cladding layer 2 using hot wire TIG welding.

[0022] Therefore, the base layer 1 is welded using submerged arc welding, utilizing the protective properties of flux to isolate air and the high deposition rate of continuous wire feeding to achieve rapid and continuous welding of the base layer 1 weld, solving the problems of frequent interruptions and low efficiency in traditional welding processes. The transition layer and cladding layer 2 are welded using hot-wire TIG welding, utilizing the characteristics of hot wire preheating to reduce the arc heat load, precisely controlling the heat input of the molten pool and the dilution rate of the base material, avoiding the dilution of the stainless steel cladding layer 2 by the carbon steel elements of the base layer 1, and ensuring the corrosion resistance of the cladding layer 2. The welding of the base layer 1, which bears the structural load, is completed first, and then the transition layer achieves a double buffer of composition and welding stress, finally completing the welding of the cladding layer 2, which bears the corrosion resistance function. The structural connection between the processes avoids mutual interference between different welding processes. At the same time, through the complementary advantages of different processes, both the structural strength requirements of the base layer 1 and the corrosion resistance requirements of the cladding layer 2 are met, which is fully adaptable to the dual working conditions of pressure bearing and corrosion resistance of the hot blast furnace shell.

[0023] In this embodiment, the beveling process includes beveling the mating ends of two composite plates to be welded, removing the oxide layer from the bevel surface, and cleaning oil, rust, and other impurities from the bevel and surrounding area to ensure a smooth and defect-free bevel surface, providing a clean bonding interface for subsequent welding. Specifically, a first bevel is machined on one of the composite plates to be welded, with an angle R1 of 40°-45°, and a second bevel is machined on the other plate, with an angle R2 of 10°-15°. Both the first and second bevels are symmetrical K-type bevels. Oil and oxide scale within 20mm on both sides of the bevel are cleaned until a metallic luster is exposed. For example, as... Figure 1 As shown, the angle R1 of the first bevel is 45°, and the angle R2 of the second bevel is 15°.

[0024] Therefore, the angled structure of the first and second bevels achieves a synergy between weld accessibility and penetration control. The first bevel, with a large angle of 40°-45°, provides ample operating space for the submerged arc welding torch, ensuring that the torch can penetrate deep into the root of the bevel and achieve full penetration welding of the base layer 1 weld, avoiding root incomplete fusion defects. At the same time, the large angle bevel disperses the welding heat input, reduces welding stress during base layer 1 welding, and avoids peeling defects at the interface between the composite plate base layer 1 and cladding layer 2. The second bevel, with a small angle of 10°-15°, strictly limits the bevel cross-sectional area during cladding layer 2 welding, reduces the amount of filler metal in cladding layer 2 welding, and shrinks the welding heat-affected zone, reducing heat input during cladding layer 2 welding. This avoids carbide precipitation problems caused by overheating of the stainless steel cladding layer 2, ensuring the corrosion resistance of cladding layer 2. At the same time, the small angle bevel limits the penetration depth during cladding layer 2 welding, preventing the welding arc from melting the carbon steel of base layer 1 and reducing the dilution of carbon steel elements to the stainless steel cladding layer 2.

[0025] In this embodiment, the welding of the base layer 1 is performed on the carbon steel base layer 1 of the composite plate using submerged arc welding. Through continuous wire feeding and full flux coverage protection, multi-layer, multi-pass welding of the base layer 1 weld is completed, achieving efficient deposition of the base layer 1 weld. The welding process controls weld formation to avoid common defects in horizontal weld positions such as incomplete fusion, undercut, and weld sagging. Specific welding parameters are: current intensity of 300A-350A, arc voltage of 30V-34V, welding speed of 25cm / min-30cm / min, flux layer thickness of 8mm-12mm, interpass temperature controlled at 150℃-200℃, and welding to a distance of 3mm-5mm from the interface of the cladding layer 2.

[0026] This achieves a synergistic effect between the deposition efficiency and the weld quality of the base layer 1 weld: a high current of 300A-350A matched with an arc voltage of 30V-34V can form a stable welding arc, increasing the deposition rate of the welding wire and enabling efficient continuous welding of the base layer 1 weld; a welding speed of 25cm / min-30cm / min can match the deposition rate, control the weld penetration and width, and avoid common defects in horizontal welds such as weld run-down and undercut. A flux thickness of 8mm-12mm forms a stable protective barrier: the flux completely covers the welding arc and the molten pool, isolating harmful gases such as oxygen and nitrogen from the air, preventing oxidation and nitriding of the molten pool metal. Simultaneously, the slag formed after the flux melts can refine the molten pool metal, removing impurities and improving the metallurgical quality of the weld; within this flux thickness range, it ensures complete arc coverage, avoiding arc radiation and spatter, while preventing poor weld formation and porosity defects due to excessive flux thickness. Interpass temperature control of 150℃-200℃ matches the welding characteristics of the base layer 1 carbon steel, avoiding welding defects: an interpass temperature not lower than 150℃ prevents rapid cooling of the weld metal to form hardened martensite, reducing the risk of cold cracking; an interpass temperature not higher than 200℃ avoids excessive welding heat input leading to increased welding residual stress, and also prevents heat transfer to the cladding layer 2 through the composite interface, causing overheating and sensitization of the cladding layer 2 stainless steel. The structural design of stopping welding at 3mm-5mm from the cladding layer 2 interface forms a buffer isolation layer between the base layer 1 weld and the cladding layer 2: the reserved 3mm-5mm carbon steel layer avoids the high-current arc melting of the composite interface during the submerged arc welding of the base layer 1, prevents the carbon steel elements of the base layer 1 from mixing into the cladding layer 2 stainless steel, and also reserves fusion space for subsequent transition layer welding, ensuring that the transition layer can form a good metallurgical bond with the base layer 1 weld, while strictly controlling the penetration depth of the base layer 1 during transition layer welding to reduce the base metal dilution rate.

[0027] In this embodiment, a transition layer is deposited on the weld surface of the completed base layer 1 using hot-wire TIG welding. The filler wire is preheated by resistance before being fed into the molten pool, and the welding heat input and molten pool state are precisely controlled to complete the transition layer weld deposit, achieving compositional buffering and metallurgical bonding between the carbon steel base layer 1 and the stainless steel cladding layer 2. Specific welding parameters are: current intensity 180A-220A, arc voltage 12V-15V, hot-wire current intensity 80A-100A, welding speed 8cm / min-12cm / min, interpass temperature ≤150℃, and penetration depth controlled at 1mm-2mm.

[0028] Thus, the coordination of hot wire current and main welding current parameters achieves synergistic control of welding deposition efficiency and dilution rate in the transition layer. The main welding current of 180A-220A is responsible for melting the base metal to form a molten pool, ensuring the metallurgical bonding between the transition layer and the base layer 1 weld. The hot wire current of 80A-100A preheats the filler wire through resistance heating, significantly reducing the arc heat required for wire melting. This allows for increased wire feeding speed and improved deposition efficiency without increasing the main arc heat input. Simultaneously, the reduced main arc heat input enables precise control of weld penetration, reducing melting of the base layer 1 carbon steel and lowering the base metal dilution rate. A welding speed of 8cm / min-12cm / min and an interpass temperature control of ≤150℃ enable precise control of the total welding heat input, preventing overheating of the cladding stainless steel layer 2. The welding speed is matched with the hot wire feed speed to ensure uniform weld formation and avoid defects such as incomplete fusion and weld beads. The interpass temperature of ≤150℃ enables control of the residence time of the welding area within the sensitization temperature range of stainless steel, preventing the precipitation of chromium carbides and reducing residual welding stress to prevent delamination of the composite interface. The 1mm-2mm penetration depth control structure achieves a balance between bonding strength and dilution rate control: the 1mm-2mm penetration depth ensures sufficient metallurgical bonding between the transition layer weld and the base layer carbon steel 1, guaranteeing the weld bonding strength and avoiding defects such as incomplete fusion and delamination; at the same time, strictly controlling the penetration depth within 2mm can minimize the melting amount of the base layer carbon steel 1, control the base material dilution rate within 10%, prevent a large amount of iron and carbon elements in the carbon steel from entering the transition layer weld, ensure the alloy element content of the transition layer weld, and provide a corrosion-resistant foundation for the cladding layer 2 weld.

[0029] In this embodiment, the filling and cover layers of the cladding layer 2 are filled and covered using hot wire TIG welding. The welding parameters are set as follows: current intensity of 160A-200A, arc voltage of 11V-14V, hot wire current intensity of 70A-90A, welding speed of 10cm / min-15cm / min, interpass temperature ≤100℃, and reinforcement height controlled at 0mm-1.5mm.

[0030] Therefore, the main welding current of 160A-200A is matched with the hot wire current of 70A-90A. The preheating of the hot wire reduces the arc heat load, which significantly reduces the total welding heat input while ensuring the deposition efficiency. The welding speed of 10cm / min-15cm / min can control the heat input per unit length of weld and avoid overheating of the weld. The strict control of the interpass temperature ≤100℃ can completely prevent the weld area from entering the sensitization temperature range of 450℃-850℃, fundamentally inhibiting the precipitation of chromium carbides and ensuring the passivation ability and corrosion resistance of the cladding layer 2 weld. The formation control of weld reinforcement height from 0mm to 1.5mm achieves a synergy between weld corrosion resistance and structural performance: controlling the reinforcement height within 1.5mm avoids stress concentration on the weld surface, preventing fatigue cracks at the weld reinforcement height location under high temperature and pressure conditions in the hot blast furnace shell; at the same time, a smooth weld surface ensures the uniformity of subsequent pickling and passivation treatment, forming a complete and dense passivation film, avoiding the risk of uneven passivation film and localized corrosion caused by excessive reinforcement height; reinforcement height ≥0mm ensures the effective thickness of the weld cross-section, avoids weakening of the weld cross-section, and guarantees the structural continuity and load-bearing capacity of the cladding layer 2 weld. The argon shielding structure of hot-wire TIG welding provides a clean welding environment for the 2-layer weld: argon, as an inert shielding gas, completely isolates harmful gases such as oxygen and nitrogen in the air, preventing the burning of easily oxidized alloying elements such as chromium and nickel in the molten pool, and ensuring the stability of the alloy composition of the weld; at the same time, the preheating of the hot wire ensures that the temperature of the welding wire is uniform when it is fed into the molten pool, the molten pool flows smoothly, the weld formation is beautiful, and there are no spatter or porosity defects, thus improving the surface quality and metallurgical quality of the weld.

[0031] In this embodiment, H10Mn welding wire with a diameter of 4.0 mm and HJ101 flux are used for submerged arc welding, and the flux is dried at 300°C for two hours; Φ1.2 mm filler wire with 385 composition is used for hot wire TIG welding.

[0032] In this embodiment of the application, the composite plate is composed of a Q345R base layer 1 and a 904L stainless steel cladding layer 2.

[0033] In this embodiment of the application, after step S2, the weld of the base layer 1 is subjected to visual inspection and ultrasonic testing within 24 hours after welding. Specifically, after the base layer 1 welding is completed, the visual inspection and ultrasonic testing (UT) of the base layer 1 weld should be completed within 24 hours. The visual inspection checks for surface defects such as cracks, lack of fusion, undercut, weld beads, and porosity on the weld surface, and the weld surface formation must meet the design requirements. The ultrasonic testing performs a full-section inspection of the weld interior, and the test results must meet the qualification requirements with no defects exceeding the standard. For defects exceeding the standard found during the inspection, they should be removed by mechanical grinding. After removal, the same submerged arc welding process should be used for repair welding. After repair welding, the inspection should be carried out again until the inspection is qualified.

[0034] Therefore, inspection within 24 hours after welding can promptly detect welding defects, preventing defects from being left in subsequent processes and causing potential quality problems. It can ensure that all welding defects are detected in a timely manner, avoiding the discovery of defects in the base layer 1 only after the transition layer and the cladding layer 2 have been welded, which would require removing the completed cladding layer 2 and the transition layer weld for rework, significantly increasing rework costs and the risk of project delays.

[0035] In this embodiment of the application, after step S3, a penetrant test is performed after welding.

[0036] Specifically, after the transition layer welding is completed, the weld is cooled to room temperature, and a penetrant test (PT) is performed on the surface of the transition layer weld. Before the penetrant test, the weld surface is cleaned of slag, spatter, oil, and other impurities to ensure that the test surface is clean and dry. After the test, it is confirmed that there are no surface opening defects such as cracks, pores, pinholes, or lack of fusion on the weld surface, and the test results meet the qualification requirements. For defects that exceed the standard found in the test, they are removed by mechanical grinding. After removal, the same hot wire TIG welding process is used for repair welding. After repair welding, the penetrant test is performed again until the test is qualified and there are no defects. Only after this can the subsequent cladding layer 2 welding process be carried out.

[0037] Therefore, the implementation of post-weld PT testing for the transition layer can promptly identify surface opening defects in the transition layer, preventing these defects from being covered by the weld of the cladding layer 2 and leaving potential quality risks. The transition layer weld is the core structure connecting the base layer 1 and the cladding layer 2. If surface opening defects such as cracks and pores are not detected in time, they will be covered by the subsequent weld of the cladding layer 2, becoming internal defects. This will not only reduce the bonding strength of the weld but also become a penetration channel for corrosive media, leading to the failure of the corrosion resistance of the cladding layer 2 and even causing the risk of shell leakage. Completing PT testing before welding the cladding layer 2 can thoroughly identify surface opening defects in the transition layer, allowing for timely repairs and ensuring the surface quality and structural integrity of the transition layer weld.

[0038] In this embodiment of the application, after step S4, the overall weld is inspected for appearance and size, and ultrasonic testing and penetrant testing are performed after 24 hours; spatter and slag on the weld surface are removed, and pickling and passivation treatment is performed on both sides of the cladding layer.

[0039] After the specific cladding layer 2 welding is completed, the overall weld is immediately inspected for appearance and dimensions. The weld surface formation, reinforcement height, and weld width are checked to confirm the absence of surface defects such as undercut, cracks, spatter, and dents, and that the weld appearance and dimensions meet the design requirements. 24 hours after welding, the entire weld is subjected to UT and PT tests. The UT test inspects the entire cross-section of the weld, and the test results for the base layer 1 weld meet the requirements. The PT test inspects the entire surface of the cladding layer 2 weld, and the test results meet the requirements, with no surface opening defects. After passing the non-destructive testing, a stainless steel wire brush and organic solvent are used to remove spatter, slag, oil, and other impurities from the weld surface and surrounding area. Then, the welds on both sides of the cladding layer 2 and the heat-affected zone are pickled and passivated to form a uniform and dense passivation film on the weld surface. After the treatment, any remaining pickling solution is cleaned from the surface to ensure a clean and residue-free surface.

[0040] Therefore, the combined UT+PT final inspection achieves closed-loop quality control of the entire weld process and cross-section. The pickling and passivation treatment on both sides of the cladding layer can repair the passivation film damaged during welding, restoring and improving the corrosion resistance of the cladding layer 2 weld. The combined process of post-weld cleaning and passivation treatment ensures the uniformity and stability of the passivation film.

[0041] 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 this application. 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.

[0042] Furthermore, the technical solutions of the various embodiments can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0043] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for welding composite plates, characterized in that, Includes the following steps: S1. Beveling treatment; S2. The base layer is welded using submerged arc welding as a filler method; S3. A transition layer is deposited on the surface of the base weld using hot-wire TIG welding; S4. Hot wire TIG welding is used to complete the cladding and cover layer.

2. The composite plate welding method according to claim 1, characterized in that, Beveling includes: Process a first bevel on one of the composite plates to be welded, with an angle of 40°-45°. Process a second bevel on the other plate, with an angle of 10°-15°. Both the first and second bevels are symmetrical K-type bevels. Clean the bevels and the area within 20mm on both sides to expose the metallic luster.

3. The composite plate welding method according to claim 1, characterized in that, Welding of the base layer using submerged arc welding filler method includes: The current intensity is 300A-350A, the arc voltage is 30V-34V, the welding speed is 25cm / min-30cm / min, the flux layer thickness is 8mm-12mm, the interpass temperature is controlled at 150℃-200℃, and the welding is performed to a distance of 3mm-5mm from the cladding interface.

4. The composite plate welding method according to claim 1, characterized in that, The transition layer deposited on the surface of the base weld using hot-wire TIG welding includes: The current intensity is 180A-220A, the arc voltage is 12V-15V, the hot wire current intensity is 80A-100A, the welding speed is 8cm / min-12cm / min, the interpass temperature is ≤150℃, and the penetration depth is controlled at 1mm-2mm.

5. The composite plate welding method according to claim 1, characterized in that, Multilayer filling and cover include: The current intensity is 160A-200A, the arc voltage is 11V-14V, the hot wire current intensity is 70A-90A, the welding speed is 10cm / min-15cm / min, the interpass temperature is ≤100℃, and the reinforcement height is controlled between 0mm and 1.5mm.

6. The composite plate welding method according to claim 1, characterized in that, The submerged arc welding uses H10Mn welding wire with a diameter of 4.0mm and HJ101 flux, and the flux is dried at 300℃ for two hours; the hot wire TIG welding uses Φ1.2mm filler wire with 385 composition.

7. The composite plate welding method according to claim 1, characterized in that, The composite plate is composed of a Q345R base layer and a 904L stainless steel cladding.

8. The composite plate welding method according to claim 1, characterized in that, After step S2, visual inspection and ultrasonic testing of the base weld are carried out within 24 hours after welding.

9. The composite plate welding method according to claim 1, characterized in that, After step S3, a penetrant test is performed after welding.

10. The composite plate welding method according to claim 1, characterized in that, After step S4, the overall weld is inspected for appearance and dimensions, and ultrasonic testing and penetrant testing are performed after 24 hours; spatter and slag on the weld surface are removed, and pickling and passivation treatment is performed on the cladding side.

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