An arc welding method based on heat redistribution

Abstract

The present disclosure provides an arc welding method based on heat redistribution, relating to the field of welding, which specifically comprises the following steps: machining the butt edges of the first base material and the second base material respectively to obtain corresponding first grooves and second grooves; using welding material to deposit at the first groove to form a weld layer; assembling the first base material and the second base material to make the first groove and the second groove butt to form a groove to-be-welded area, and uniformly preheating the groove to-be-welded area; wherein the weld layer is located in the groove to-be-welded area; one welding is performed on the groove to-be-welded area to form an initial weld seam; then secondary welding and tertiary welding are sequentially performed on the initial weld seam to form a complete weld seam; and post-heat treatment is performed on the complete weld seam, and after the post-heat treatment is completed, a welded component is obtained. The present disclosure solves the problem of uneven distribution of arc heat input between the two base materials.

Description

Technical Field

[0001] This disclosure relates to the field of welding, and more particularly to an arc welding method based on heat redistribution. Background Technology

[0002] Arc welding is one of the most widely used joining processes in the manufacture of pressure vessels, storage tanks, pipelines, and other low-alloy steel welded structures. It utilizes the heat generated by an electric arc to locally melt the base material and the welding material, forming a welded joint upon cooling and solidification. For pressure vessels made of low-alloy steel, the actual manufacturing process often requires welding low-alloy steels of different strength grades to balance the load-bearing capacity, material utilization, and manufacturing costs of different parts of the equipment. Current processes typically involve machining bevels on both sides of the base material for assembly, followed by layer-by-layer root pass, fill pass, and cap pass welding to form a complete weld. This is combined with preheating, post-heat treatment, and welding parameter adjustments to obtain a welded joint that meets the strength and sealing performance requirements.

[0003] However, in existing processes for arc welding the grooved area formed by the base materials on both sides, there is an uneven distribution of arc heat input between the two base materials. Specifically, when the strength grades or weldability of the two base materials differ, their thermal conductivity, melting point range, chemical composition, and melting characteristics also differ. When the arc acts on the grooved area, the heat input is transferred to both base materials and the welding material separately. The heat distribution ratio within the grooved area continuously changes with the melting state of the base materials, resulting in the base materials not melting synchronously. One side of the base material may enter the melting state earlier, while the other side retains a higher proportion of solid structure, causing changes in the composition of the molten pool formed within the grooved area, continuous displacement of the molten pool boundary, and decreased molten pool stability. After the molten pool solidifies, defects such as localized incomplete fusion, incomplete penetration, or micro-shrinkage cavities are easily formed in the root region of the groove. Since subsequent filler and capping welds primarily work above the existing initial weld, the newly added weld metal mainly covers the upper layer of the weld. This makes it difficult to fully melt and eliminate localized defects already formed at the root, resulting in these defects remaining inside the weld joint. When the weld joint is used in structures with sealing requirements, such as pressure vessels, these residual micro-defects at the weld root can easily form channels for media penetration, thereby reducing the sealing performance and long-term service reliability of the weld joint.

[0004] Therefore, an arc welding method based on heat redistribution is proposed to solve the problem of uneven distribution of arc heat input between the two base materials. Summary of the Invention

[0005] The purpose of this disclosure is to provide an arc welding method based on heat redistribution to solve the problem of uneven distribution of arc heat input between the two base materials.

[0006] To achieve this objective, the present disclosure adopts the following technical solution: An arc welding method based on heat redistribution, the welding method specifically includes the following steps: Step S1: Machining is performed on the mating edges of the first and second base materials to obtain the corresponding first bevel and second bevel; Step S2: Use welding material to deposit a weld layer at the first bevel; Step S3: Assemble the first base material and the second base material so that the first bevel and the second bevel are joined to form a bevel welding area, and uniformly preheat the bevel welding area; wherein, the weld layer is located in the bevel welding area. Step S4: Perform a first weld on the bevel area to be welded to form an initial weld; then perform a second and third weld on the initial weld to form a complete weld; then perform post-heat treatment on the complete weld, and after the post-heat treatment is completed, the welded component is obtained.

[0007] The first bevel and the second bevel are obtained according to the following steps: First, fix the first and second base materials in the machining fixture, and make the mating edges of the first and second base materials face the cutting tool respectively; then, use milling to cut the mating edges of the first base material to form an inclined bevel surface and a blunt edge, thus obtaining the first bevel; use milling to cut the mating edges of the second base material to form an inclined bevel surface and a blunt edge, thus obtaining the second bevel.

[0008] In step S1, both the first base material and the second base material are any one of Q345R low alloy steel plate, Q355R low alloy steel plate, and Q370R low alloy steel plate, and the strength grade of the first base material is not lower than that of the second base material; the thickness of both the first base material and the second base material is 12-20mm; the welding material is a solid low alloy steel welding wire with a diameter of 1.0-1.2mm. Both the first and second bevels are single-sided V-shaped bevels; the bevel angles of both the first and second bevels are 55-65° and the blunt edges are 1.0-2.0mm.

[0009] Step S2 specifically includes the following steps: Step S21: Fix the first base material after the first bevel is formed onto the welding fixture, and make the side wall of the bevel root of the first bevel face the welding gun. Step S22: The welding material is fed to the end of the welding torch through the wire feeding mechanism, and the electric arc is ignited at the first bevel. Step S23: Use pulsed MAG welding to melt the welding material and deposit the molten welding material on the root sidewall of the first bevel. Step S24: Control the welding torch to move along the length of the first bevel, so that the molten welding material is continuously deposited along the length of the first bevel and forms a weld layer after solidification.

[0010] In step S24, the weld layer is continuously distributed along the length of the first bevel, and the weld layer is located on the side wall of the bevel root of the first bevel and is set close to the root of the first bevel; the thickness of the weld layer is 0.4-0.8mm and the width is 2.0-4.0mm.

[0011] In steps S23 to S24, the peak current for forming the weld layer is 220-280A, the base current is 40-80A, the pulse frequency is 80-120Hz, the pulse width is 2.0-4.0ms, the pulse duty cycle is 20-35%, the wire feed speed is 3.5-5.0m / min, the arc voltage is 19-23V, the welding speed is 180-260mm / min, and the shielding gas flow rate is 15-22L / min.

[0012] Step S3 specifically includes the following steps: Step S31: Place the first base material with the weld layer and the second base material with the second bevel on the assembly fixture, and set the first bevel and the second bevel opposite each other; Step S32: Adjust the relative position between the first base material and the second base material so that the first bevel and the second bevel are joined to form a bevel welding area, and make the weld layer located in the bevel welding area; Step S33: Position and fix the first base material and the second base material, and control the root gap of the bevel to be welded area and the misalignment between the first base material and the second base material; Step S34: Preheat the bevel area to be welded evenly.

[0013] In step S33, the root gap of the bevel welding area is 2.0-3.0mm, and the misalignment between the first base material and the second base material is 0.5-1.5mm. In step S34, the preheating temperature for uniform preheating is 100-140℃.

[0014] Step S4 specifically includes the following steps: Step S41: Perform a single welding operation on the root area of ​​the groove to be welded using pulsed MAG welding, so that the welding material melts and enters the groove to be welded, and at the same time the weld layer remelts and solidifies to form the initial weld. Step S42: Use MAG welding to perform secondary welding on the initial weld, so that the welding material melts and deposits on the initial weld to form an intermediate welding area; Step S43: Perform three welding operations on the intermediate welding area using MAG welding, so that the welding material melts and deposits on the intermediate welding area to form a complete weld. Step S44: Perform post-heat treatment on the complete weld and the base material areas on both sides of the complete weld. After the post-heat treatment is completed, the welded component is obtained.

[0015] In step S41, the peak current of the first welding operation is 300-380A, the base current is 80-120A, the pulse frequency is 90-150Hz, the pulse width is 3.0-5.0ms, the pulse duty cycle is 30-45%, the wire feed speed is 4.5-6.5m / min, the arc voltage is 22-26V, the welding speed is 180-260mm / min, and the shielding gas flow rate is 18-22L / min; the arc center of the first welding operation is offset by 0.3-0.5mm towards the first base material. In step S42, the welding current for the secondary welding is 200-260A, the arc voltage is 24-30V, the welding speed is 250-350mm / min, and the shielding gas flow rate is 18-22L / min. In step S43, the welding current for the three welding operations is 190-240A, the arc voltage is 23-28V, the welding speed is 260-360mm / min, and the shielding gas flow rate is 18-22L / min. In step S44, the temperature of the post-heat treatment is 200-240℃, and the time of the post-heat treatment is 0.5-1.5h.

[0016] Compared with the prior art, this disclosure has the following beneficial effects: This disclosure provides an arc welding method based on heat redistribution. After forming a first bevel and a second bevel with a first base material and a second base material, a weld layer is pre-formed at the first bevel. The first bevel and the second bevel are assembled to form a bevel welding area. After preheating, a single welding operation is performed, causing the weld layer to remelt during the welding process and participate in the initial weld formation. This allows the arc heat input to act not only on the first base material, the second base material, and the continuously fed welding material, but also on the weld layer, causing the weld layer to remelt. This adjusts the arc heat input transfer process within the bevel welding area, reducing the asynchronous melting phenomenon caused by the difference in welding performance between the first base material and the second base material. This makes the molten pool formed within the bevel welding area more stable, reducing changes in molten pool composition and molten pool boundary offset. Subsequently, a complete weld is formed through secondary and tertiary welding, and post-heat treatment is performed to keep the complete weld continuous and stable. This reduces the possibility of defects such as incomplete fusion, incomplete penetration, and micro-shrinkage cavities at the root of the bevel, and reduces the possibility of the welded joint forming a medium penetration channel. This is beneficial to improving the sealing performance and long-term service reliability of the welded joint. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0018] The structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which this disclosure can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size should still fall within the scope of the technical content disclosed herein, provided that they do not affect the effectiveness and purpose that this disclosure can achieve.

[0019] Figure 1 This is a flowchart of the welding method in an embodiment of this disclosure. Detailed Implementation

[0020] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be more thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art.

[0021] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a thorough understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure can be practiced without one or more of the specific details, or other methods, components, apparatuses, steps, etc., can be employed. In other instances, well-known methods, apparatuses, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of this disclosure.

[0022] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0023] The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0024] Please see Figure 1 An arc welding method based on heat redistribution, the welding method specifically includes the following steps: Step S1: Machining is performed on the mating edges of the first and second base materials to obtain the corresponding first bevel and second bevel; Step S2: Use welding material to deposit a weld layer at the first bevel; Step S3: Assemble the first base material and the second base material so that the first bevel and the second bevel are joined to form a bevel welding area, and uniformly preheat the bevel welding area; wherein, the weld layer is located in the bevel welding area. Step S4: Perform a first weld on the bevel area to be welded to form an initial weld; then perform a second and third weld on the initial weld to form a complete weld; then perform post-heat treatment on the complete weld, and after the post-heat treatment is completed, the welded component is obtained.

[0025] Specifically, in step S1, the mating edges of the first base material and the second base material are machined to obtain the corresponding first bevel and second bevel; The first and second bevels are obtained according to the following steps: First, fix the first and second base materials in the machining fixture, and make the mating edges of the first and second base materials face the cutting tool respectively; then, use milling to cut the mating edges of the first base material to form an inclined bevel surface and a blunt edge, thus obtaining the first bevel; use milling to cut the mating edges of the second base material to form an inclined bevel surface and a blunt edge, thus obtaining the second bevel.

[0026] In step S1, both the first base material and the second base material are any one of Q345R low alloy steel plate, Q355R low alloy steel plate, and Q370R low alloy steel plate, and the strength grade of the first base material is not lower than that of the second base material; the thickness of both the first base material and the second base material is 12-20mm; the welding material is a solid low alloy steel welding wire with a diameter of 1.0-1.2mm; Both the first and second bevels are single-sided V-shaped bevels; the bevel angles of both the first and second bevels are 55-65°, and the blunt edges are both 1.0-2.0mm.

[0027] It should be noted that step S1 uses the first and second base materials as input objects, and performs machining processing on the mating edges of the first and second base materials respectively. Specifically, the first and second base materials are fixed on the clamping fixture of the machining equipment, so that the mating edges on both sides are in the predetermined machining position. Then, the mating edges of the first and second base materials are continuously cut by milling, so that part of the material at the mating edges is gradually removed according to the predetermined machining trajectory, forming the corresponding first and second bevels. The first and second bevels are both machined as single-sided V-shaped bevels with a bevel angle of 55-65° and a blunt edge of 1.0-2.0mm. After the beveling is completed, the first and second bevels are mechanically ground to remove burrs, attachments, and local oxide layers formed during the machining process, finally obtaining the first and second base materials that meet the assembly requirements. Throughout the entire processing, both the first and second base materials remain solid, with only localized material removal occurring. The melting and solidification processes are not involved, thus maintaining the overall structure of the first and second base materials. Meanwhile, the mating edges form a first bevel and a second bevel with predetermined geometric dimensions, providing a unified processing foundation for subsequent processes.

[0028] It is known that the first and second bevels use the same bevel structure and processing parameters, ensuring consistent geometric dimensions and correspondence between the two bevels. Specifically, a bevel angle of 55-65° is used to form a bevel opening that meets welding space requirements, and a 1.0-2.0mm blunt edge is used to retain a certain thickness of base material at the bevel root, maintaining stable structural strength at the bevel root. Simultaneously, milling the first and second bevels ensures a continuous machined surface, reducing geometric deviations caused by dimensional fluctuations and enabling the first and second bevels to form dimensionally stable welding areas during subsequent assembly. Because the first and second bevels have consistent spatial dimensions, the subsequent electric arc can always act on the predetermined welding area, providing a geometric boundary for maintaining a stable range of arc heat input within the welding area.

[0029] It is understandable that when base materials with different welding properties are welded, if there are differences in the bevel size or assembly boundary, the arc's position is prone to shift with changes in the bevel geometry, leading to changes in the arc heat input area and further affecting the melting state of the base materials on both sides. This disclosure firstly forms a first and second bevel of consistent size through machining, enabling the first and second base materials to form geometrically stable bevel welding areas during subsequent assembly. This ensures that the arc always acts within a relatively fixed area during subsequent welding, providing a geometric basis for the stable transfer of arc heat input along the bevel welding area. It should be noted that this step does not directly change the way arc heat input is transferred, but rather creates a stable bevel structure to establish unified boundary conditions for adjusting the arc heat input path in subsequent steps. Therefore, step S1 is a fundamental step in the entire heat redistribution process.

[0030] It is worth noting that this step uses machining to form the first and second bevels, rather than flame cutting or plasma cutting to directly form the bevels. This avoids the formation of a significant remelted layer or slag adhesion layer at the bevel edges, which helps maintain the dimensional accuracy and surface consistency of the first and second bevels. Simultaneously, by controlling the bevel angle and blunt edge dimensions, the first and second bevels ensure that, while meeting subsequent assembly requirements, they reserve stable mounting positions for the formation of the weld layer in subsequent steps, and allow the first and second bevels to form a dimensionally stable bevel area to be welded after assembly. Therefore, step S1 not only completes the machining of the first and second bevels but also establishes a unified geometric boundary required for subsequent weld layer formation and arc heat input, enabling the entire welding process to be implemented progressively around the same bevel area to be welded.

[0031] It should also be noted that the machining method is CNC milling, which is a technical means well known to those skilled in the art, and will not be described in detail in this disclosure.

[0032] Specifically, in step S2, welding material is deposited at the first bevel to form a weld layer; Step S2 specifically includes the following steps: Step S21: Fix the first base material after the first bevel is formed onto the welding fixture, and make the side wall of the bevel root of the first bevel face the welding gun. Step S22: The welding material is fed to the end of the welding torch through the wire feeding mechanism, and the electric arc is ignited at the first bevel. Step S23: Use pulsed MAG welding to melt the welding material and deposit the molten welding material on the root sidewall of the first bevel. Step S24: Control the welding torch to move along the length of the first bevel, so that the molten welding material is continuously deposited along the length of the first bevel and forms a weld layer after solidification.

[0033] In step S24, the weld layer is continuously distributed along the length of the first bevel. The weld layer is located on the side wall of the root of the first bevel and is set close to the root of the first bevel. The thickness of the weld layer is 0.4-0.8 mm and the width is 2.0-4.0 mm.

[0034] In steps S23 to S24, the peak current during weld formation is 220-280A, the base current is 40-80A, the pulse frequency is 80-120Hz, the pulse width is 2.0-4.0ms, the pulse duty cycle is 20-35%, the wire feed speed is 3.5-5.0m / min, the arc voltage is 19-23V, the welding speed is 180-260mm / min, and the shielding gas flow rate is 15-22L / min.

[0035] It should be noted that step S2 uses the first base material as the input object. After completing the first beveling process, the first base material is fixed on the welding fixture to keep the first beveling stably positioned along the welding direction, and to ensure that the root sidewall of the first beveling is within the welding action range of the welding torch. Subsequently, the welding material is continuously fed to the end of the welding torch via the wire feeding mechanism, and a stable arc is established at the first beveling using pulsed MAG welding. The welding material gradually melts under the heat of the arc to form molten droplets, which continuously transition to the root sidewall of the first beveling along the arc action direction. As the welding torch moves at a uniform speed along the length of the first beve, the molten welding material spreads out and gradually solidifies, forming a continuously distributed weld layer on the root sidewall of the first beveling. The weld layer is continuously arranged along the length of the first beve, with a thickness of 0.4-0.8 mm and a width of 2.0-4.0 mm, and is formed close to the root of the first beve. After the weld layer is formed, the overall structure of the first base material remains unchanged. Only the surface of the first bevel is added with a continuous weld layer, that is, a weld layer that is continuously formed along the length of the first bevel, thus obtaining the first base material with the weld layer, providing a pre-treated component for subsequent assembly.

[0036] It should also be noted that the weld layer is a continuous metal layer formed on the surface of the first bevel by fusion deposition, and it maintains a fixed spatial positional relationship with the first bevel during subsequent assembly and welding processes.

[0037] It is known that step S2 uses pulsed MAG welding to form the weld layer, controlling the peak current to be 220-280A, the base current to be 40-80A, the pulse frequency to be 80-120Hz, the pulse width to be 2.0-4.0ms, the wire feed speed to be 3.5-5.0m / min, the welding speed to be 180-260mm / min, and the shielding gas flow rate to be 15-22L / min. This allows the welding material to be deposited on the root sidewall of the first bevel in a stable droplet transfer manner. The peak current ensures sufficient melting of the welding material, the base current maintains continuous arc combustion, the pulse frequency and pulse width jointly control the droplet transfer rhythm, and the wire feed speed and welding speed jointly control the continuous formation of the weld layer along the length of the first bevel. This ensures that the weld layer maintains a uniform size and remains attached to the surface of the first bevel without altering its original geometry.

[0038] Understandably, existing welding processes typically begin welding directly after the first and second base materials are assembled. The welding materials used in the bevel area are mainly derived from the continuously fed materials during the welding process, and there is no pre-formed welding material layer in the bevel area before welding begins. In this disclosure, after the first base material is beveled, a continuous weld layer is pre-formed on the first bevel, so that the first base material has a stable weld layer structure attached to the surface of the first bevel before entering the assembly process. Since the weld layer is always fixed to the first bevel, it can enter the bevel area along with the first bevel during subsequent assembly without needing to be repositioned or re-formed. This results in an initial welding material distribution state in the bevel area before welding begins that differs from conventional welding processes, establishing a stable material basis for subsequent welding processes.

[0039] It is worth noting that the purpose of forming the weld layer in step S2 is not to pre-form the weld, but to form a weld layer with a predetermined size and fixed spatial position on the surface of the first bevel, ensuring that the weld layer maintains a consistent positional relationship with the first bevel and enters the bevel-to-weld area formed in step S3 along with the first bevel. Therefore, after step S2 is completed, the position of the weld layer no longer changes due to the assembly process, nor does it need to be adjusted again after assembly. When step S3 completes the assembly of the first and second base materials, the weld layer can be stably positioned within the bevel-to-weld area, providing stable initial welding material distribution conditions for the welding process in step S4. It should be noted that this step does not directly change the arc heat input transfer method in the welding process, but rather, by forming the weld layer, it provides the necessary material basis for the subsequent arc heat input transfer process in the bevel-to-weld area to form a transfer process different from conventional welding processes, making the entire welding method a continuous process flow from bevel processing, weld layer formation, assembly positioning to welding implementation.

[0040] Specifically, in step S3, the first base material and the second base material are assembled so that the first bevel and the second bevel are joined to form a bevel welding area, and the bevel welding area is uniformly preheated; wherein, the weld layer is located in the bevel welding area. Step S3 specifically includes the following steps: Step S31: Place the first base material with the weld layer and the second base material with the second bevel on the assembly fixture, and set the first bevel and the second bevel opposite each other; Step S32: Adjust the relative position between the first base material and the second base material so that the first bevel and the second bevel are joined to form a bevel welding area, and make the weld layer located in the bevel welding area; Step S33: Position and fix the first base material and the second base material, and control the root gap of the bevel to be welded area and the misalignment between the first base material and the second base material; Step S34: Preheat the bevel area to be welded evenly.

[0041] In step S33, the root gap of the groove to be welded area is 2.0-3.0mm, and the misalignment between the first base material and the second base material is 0.5-1.5mm; In step S34, the preheating temperature for uniform preheating is 100-140℃.

[0042] It should be noted that step S3 uses a first base material and a second base material with a weld layer as input objects. First, the first and second base materials are placed on the assembly fixture, with the first and second bevels aligned symmetrically along the butt joint direction. Then, the relative positions of the first and second base materials are slowly adjusted, bringing the first and second bevels closer together until butt joint is completed, forming a bevel-to-weld area between the two bevels. The weld layer remains attached to the root sidewall of the first bevel and enters the bevel-to-weld area synchronously with the first bevel without any change in relative position. After butt joint is completed, the first and second base materials are positioned and fixed, and the root gap of the bevel-to-weld area is adjusted to 2.0-3.0 mm, and the misalignment between the first and second base materials is adjusted to 0.5-1.5 mm. Subsequently, the entire bevel area to be welded is uniformly preheated, raising the temperature of the first base material, the second base material, and the weld layer to 100-140℃ and maintaining this temperature for a predetermined time, so that the assembly to be welded forms a uniform initial thermal state before welding. After completing this step, the assembled and preheated assembly to be welded is obtained, providing the welding object for the first welding operation in step S4.

[0043] It is understood that this step controls the assembly position of the first and second bevels to form a dimensionally stable bevel welding area on both sides. By adjusting the root gap and misalignment, the spatial dimensions of the bevel welding area are kept consistent along the entire welding direction. Specifically, the root gap defines the space for welding material to fill within the bevel welding area, and the misalignment ensures a stable correspondence between the first and second base materials, allowing the weld layer to always be positioned at a predetermined location within the bevel welding area closer to the first base material. Simultaneously, by uniformly preheating the entire bevel welding area, a relatively consistent pre-welding temperature field is established among the first and second base materials and the weld layer, reducing the initial temperature differences between different locations within the bevel welding area at the start of welding and providing a stable initial thermal state for subsequent welding.

[0044] Understandably, existing welding processes typically involve direct welding after assembling the first and second base materials. Due to differences in thermal conductivity and weldability between the base materials, the responses of the two base materials to arc heat input are asynchronous at the start of welding, causing localized areas within the bevel welding region to preferentially enter a melting state. This disclosure, after forming the weld layer in step S2, uses step S3 to stably introduce the weld layer into the bevel welding region, maintaining a fixed spatial correspondence between the weld layer and the first bevel. Simultaneously, a consistent pre-welding temperature field is established through unified preheating, ensuring that the weld layer, the first base material, and the second base material are in similar initial thermal states before welding begins. Therefore, this step does not directly alter the arc heat input transfer path during welding. Instead, by fixing the position of the weld layer and establishing a unified pre-welding thermal environment, it creates stable conditions for the arc heat input to act on the bevel welding region along a predetermined path in the subsequent step S4, ensuring a consistent initial state for the subsequent arc heat input control process.

[0045] It is worth noting that this step adopts a process sequence of completing assembly first and then preheating the whole, rather than preheating the first and second base materials separately before completing assembly. This is because after the weld layer is formed, it has already formed a fixed integral structure with the first bevel. If preheating is performed separately before assembly, there may still be local temperature differences between the first bevel, the second bevel, and the weld layer during the assembly process, which is not conducive to establishing a unified pre-welding thermal state for the assembly to be welded. This disclosure preheats the entire bevel area to be welded after assembly, so that the first base material, the second base material, and the weld layer gradually form a continuous and uniform temperature distribution under the same assembly state, and keep the weld layer always within the subsequent arc action area. After completing this step, the assembly to be welded has a stable geometric boundary, a stable weld layer position, and a unified pre-welding initial thermal state, so that step S4 can directly perform welding under stable and consistent initial welding conditions, providing a unified initial basis for the subsequent arc heat input to form a transfer process different from conventional welding processes.

[0046] It should also be noted that the uniform preheating of the bevel area to be welded is carried out by electric heating. The specific electric heating method is a technical means well known to those skilled in the art, and will not be described in detail in this disclosure.

[0047] Specifically, in step S4, the bevel area to be welded is welded once to form an initial weld; then, a second and third weld are performed on the initial weld to form a complete weld; the complete weld is then subjected to post-heat treatment, and after the post-heat treatment is completed, the welded component is obtained.

[0048] Step S4 specifically includes the following steps: Step S41: Perform a single welding operation on the root area of ​​the groove to be welded using pulsed MAG welding, so that the welding material melts and enters the groove to be welded, and at the same time the weld layer remelts and solidifies to form the initial weld. Step S42: Use MAG welding to perform secondary welding on the initial weld, so that the welding material melts and deposits on the initial weld to form an intermediate welding area; Step S43: Perform three welding operations on the intermediate welding area using MAG welding, so that the welding material melts and deposits on the intermediate welding area to form a complete weld. Step S44: Perform post-heat treatment on the complete weld and the base material areas on both sides of the complete weld. After the post-heat treatment is completed, a welded component is obtained, which refers to the integral workpiece formed by the connection of the first base material and the second base material through the complete weld, including the welded joint and the base material on both sides of the welded joint.

[0049] In step S41, the peak current of a single welding operation is 300-380A, the base current is 80-120A, the pulse frequency is 90-150Hz, the pulse width is 3.0-5.0ms, the pulse duty cycle is 30-45%, the wire feed speed is 4.5-6.5m / min, the arc voltage is 22-26V, the welding speed is 180-260mm / min, and the shielding gas flow rate is 18-22L / min; the arc center of the single welding operation is offset by 0.3-0.5mm towards the first base material. In step S42, the welding current for the secondary welding is 200-260A, the arc voltage is 24-30V, the welding speed is 250-350mm / min, and the shielding gas flow rate is 18-22L / min; In step S43, the welding current for the three welding operations is 190-240A, the arc voltage is 23-28V, the welding speed is 260-360mm / min, and the shielding gas flow rate is 18-22L / min. In step S44, the temperature of the post-heat treatment is 200-240℃, and the time of the post-heat treatment is 0.5-1.5h.

[0050] It should be noted that step S4 uses the assembly to be welded as the input object, and welding begins when the first base material, the second base material, and the weld layer are all in a uniform initial thermal state before welding. First, a welding arc is established in the bevel area to be welded, and welding materials are continuously fed, causing the welding materials to gradually melt and form droplets under the heat of the arc. At the same time, the arc is controlled to move continuously along the length of the bevel area to be welded, so that the arc always acts on the bevel area to be welded. During one welding process, the continuously fed welding materials and the weld layer are both within the arc's range of action. The weld layer gradually remelts and participates in the formation of the initial molten pool together with the continuously fed welding materials. As the welding torch moves continuously along the welding direction, the initial molten pool gradually solidifies to form the initial weld. After completing one welding, a second welding is performed on the basis of the initial weld, so that the continuously fed welding materials continuously fill the space above the initial weld to form an intermediate welding area. Then, a third welding is performed, so that the continuously fed welding materials further cover the intermediate welding area, gradually completing the filling of the upper space of the bevel area to be welded, and finally forming a complete weld covering the entire bevel area to be welded. After welding is completed, post-heat treatment is performed on the complete weld and its adjacent base material area to gradually complete the post-weld stabilization treatment of the welded joint and obtain the welded component.

[0051] It should also be noted that, because the weld layer is located on the sidewall of the root of the first bevel, it comes into contact with the arc heat input first during a single welding process. This causes the arc heat input to preferentially act on the weld layer before entering the base metal on both sides, triggering its phase change, heat absorption, and melting behavior. This alters the initial absorption path of the arc heat input within the bevel welding area, causing a redistribution of the subsequent arc heat input among the weld layer, molten welding material, and base metal. Simultaneously, because the weld layer is located within the initial arc action area, it melts first during a single welding process, thus preferentially acting on the weld layer before entering the base metal.

[0052] Compared with the prior art, this disclosure achieves the retransmission of heat input in the bevel welding area by forming a weld layer at the first bevel and having the weld layer participate in a welding process, thereby reducing the influence of base materials with different welding properties on the heat input process.

[0053] It is understood that the welding in this disclosure employs pulsed MAG welding, with peak current controlled at 300-380A, base current controlled at 80-120A, pulse frequency controlled at 90-150Hz, pulse width controlled at 3.0-5.0ms, pulse duty cycle controlled at 30-45%, wire feed speed controlled at 4.5-6.5m / min, welding speed controlled at 180-260mm / min, shielding gas flow rate controlled at 18-22L / min, and the arc center offset towards the first base material side by 0.3-0.5mm. These parameters ensure that the arc heat input first fully acts on the area where the weld layer is located, enabling the weld layer to stably remelt and participate in the initial molten pool formation. Furthermore, since the weld layer is located on the first bevel side, and the arc center is offset towards the first base material side, the arc first acts on the area where the weld layer is located, which is beneficial for the stable remelting of the weld layer. Both the secondary and tertiary welding processes employed MAG welding. The secondary welding primarily filled the central portion of the bevel area to be welded, while the tertiary welding filled the upper portion and formed the weld surface. Both welding processes maintained continuous wire feeding and continuous welding, ensuring a continuous weld along the entire bevel area. The post-weld heat treatment temperature was controlled at 200-240℃, with a holding time of 0.5-1.5 hours, to complete the post-weld heat treatment process.

[0054] Understandably, existing welding processes typically involve direct welding in the bevel area, with the arc heat input primarily acting directly on the base materials on both sides and the continuously fed welding material. When there are differences in the weldability of the base materials on both sides, their responses to the arc heat input are asynchronous, easily leading to insufficient melting in the bevel root area, causing continuous changes in the molten pool composition, and further resulting in defects such as incomplete fusion and incomplete penetration. In this disclosure, a weld layer is pre-formed in step S2, and in step S3, the weld layer is stabilized within the bevel area. When a welding operation begins in step S4, the arc heat input, in addition to acting on the continuously fed welding material and the base materials on both sides, first acts on the weld layer, causing it to remelt and participate in the initial molten pool formation. Since the weld bead is fixed to the first bevel side before welding begins, a portion of the arc heat input is first used for the remelting of the weld bead. Subsequently, the remelted weld bead, together with the continuously fed welding material, participates in the formation of the molten pool. This transforms the arc heat input, which originally acted primarily on the base materials on both sides, into an arc heat input process that simultaneously acts on the weld bead, welding material, and base materials. Thus, the arc heat input transfer method within the bevel welding area changes from direct transfer in conventional welding processes to a re-transfer process involving the weld bead. This redistributes the arc heat input within the bevel welding area and reduces the impact of differences in the welding performance of the base materials on the melting state at the bevel root, making the initial molten pool formation process more stable. Subsequently, secondary and tertiary welding ensures continuous filling of the weld along the entire bevel welding area, further maintaining and extending the arc heat input effect from the first welding into the complete weld formation process, ultimately forming a continuous and complete welded joint. In addition, since the weld layer melts first in the initial stage of the electric arc, its remelting process consumes part of the electric arc heat input and changes the initial molten pool formation process in the groove waiting area. This causes part of the heat input that originally acted directly on the first base material and the second base material to act on the weld layer first and then participate in the formation of the molten pool, thereby changing the heat input transmission sequence in the groove waiting area and thus affecting the melting process of the first base material and the second base material.

[0055] It is worth noting that in this disclosure, the weld layer is not retained as an independent weld within the welded joint. Instead, it remelts during a single welding process and, together with the continuously fed welding materials, forms the initial weld. Therefore, the weld layer ultimately becomes part of the complete weld, rather than forming an independent interface. Furthermore, the primary, secondary, and tertiary welding processes are performed sequentially in a continuous process order, allowing the bevel area to be welded to be gradually completed along the thickness direction, rather than forming separate, independent weld layers. After the complete weld is formed, an overall post-heat treatment is performed, allowing the weld and adjacent base metal areas to undergo post-weld microstructure stabilization, reducing residual welding stress, and resulting in a continuous and stable microstructure in the welded joint. After the complete weld is formed and post-heat treated, a continuous weld structure is formed within the bevel area, reducing the possibility of root defects forming through channels, thereby improving the sealing reliability of the welded joint. Therefore, step S4, based on the establishment of a unified geometric boundary, the formation of a weld layer, and the establishment of a unified initial thermal state before welding, achieves the retransmission of arc heat input in the bevel welding area through the participation of the weld layer in a welding process. Combined with subsequent continuous welding and post-weld treatment, the entire welded joint is formed, thus forming a complete and continuous process flow for the entire technical solution.

[0056] It should also be noted that the shielding gas used in steps 2 and 4 for MAG welding and pulsed MAG welding is a mixture of Ar and CO2 shielding gas; MAG welding is a gas metal arc welding; and pulsed MAG welding is MAG welding using pulsed current control.

[0057] This disclosure describes a method for obtaining welded components using an arc welding method based on heat redistribution, as detailed in Examples 1, 2, and 3.

[0058] Example 1: This embodiment provides an arc welding method based on heat redistribution, and its specific implementation process is as follows.

[0059] First, two base materials were selected. The first base material was made of Q370R low-alloy steel plate, and the second base material was made of Q345R low-alloy steel plate, both with a thickness of 16mm. Then, the mating edges of the first and second base materials were CNC milled to form a first bevel and a second bevel, respectively. Both bevels were machined as single-sided V-shaped bevels with a bevel angle of 60° and a blunt edge of 1.5mm. After beveling, the bevel surfaces were mechanically ground to remove burrs and oxide layers, and then cleaned with anhydrous ethanol to complete the bevel pretreatment.

[0060] Subsequently, a 1.2mm diameter low-alloy steel solid welding wire was selected as the welding material, and pulsed MAG welding was used to form a weld layer on the root sidewall of the first bevel. The weld layer was continuously deposited along the length of the first bevel, with a thickness controlled at 0.6mm and a width controlled at 3.0mm. During the welding process, the peak current was 250A, the base current was 60A, the pulse frequency was 100Hz, the pulse width was 3.0ms, the pulse duty cycle was 30%, the wire feed speed was 4.2m / min, the welding speed was 220mm / min, the arc voltage was 21V, and the shielding gas flow rate was 18L / min, so that the weld layer was uniformly adhered to the root sidewall of the first bevel, forming a continuous weld layer.

[0061] After the weld layer is formed, the first and second base materials are installed in the assembly fixture, so that the first and second bevels are aligned and joined to form the bevel welding area. The root gap of the bevel welding area is controlled at 2.5 mm, and the misalignment is controlled at 1.0 mm. Then, the entire bevel welding area is uniformly preheated by electric heating, so that the first base material, the second base material, and the weld layer are heated to 120°C and held at that temperature for 15 minutes to establish a uniform initial thermal state before welding.

[0062] After preheating, the bevel area to be welded is subjected to a single welding operation. The single welding operation uses pulsed MAG welding with a peak current of 340A, a base current of 100A, a pulse frequency of 120Hz, a pulse width of 4.0ms, a pulse duty cycle of 35%, a wire feed speed of 5.5m / min, a welding speed of 220mm / min, an arc voltage of 24V, and a shielding gas flow rate of 20L / min. The arc center is offset by 0.4mm towards the first base material. During welding, the weld layer first remelts and, together with the continuously fed welding material, participates in the initial molten pool formation, forming a continuous initial weld.

[0063] A second welding operation was then performed using MAG welding at a welding current of 230A, an arc voltage of 27V, a welding speed of 300mm / min, and a shielding gas flow rate of 20L / min. This continuously filled the initial weld seam, forming the intermediate welding area. A third welding operation was then performed using MAG welding at a welding current of 210A, an arc voltage of 25V, a welding speed of 320mm / min, and a shielding gas flow rate of 20L / min. This completed the capping welding of the bevel area, ultimately forming a complete weld seam.

[0064] After welding, post-heat treatment is performed on the complete weld and the adjacent base material area. The post-heat treatment temperature is 220℃ and the holding time is 1.0h. Then, it is naturally cooled to room temperature to obtain the welded component.

[0065] Example 2: The basic content is the same as in Example 1, except that: The first base material is Q355R low alloy steel plate, and the second base material is Q345R low alloy steel plate, both with a thickness of 14mm; the bevel angle of the first and second bevels is 58°; the weld layer thickness is 0.5mm; the root gap of the bevel to be welded area is 2.2mm; the uniform preheating temperature is 110℃; the peak current of the first welding is 320A, the base current is 90A, and the arc center offset is 0.3mm; the second welding current is 220A; the third welding current is 200A; the post-heat treatment temperature is 210℃, and the holding time is 0.8h.

[0066] The remaining process steps are the same as in Example 1.

[0067] Example 3: The basic content is the same as in Example 1, except that: The first base material is Q370R low alloy steel plate, and the second base material is Q355R low alloy steel plate, both with a thickness of 20mm. The bevel angle of the first and second bevels is 62°, and the blunt edge is 2.0mm. The weld layer thickness is 0.8mm and the width is 3.5mm. The root gap of the bevel to be welded area is 2.8mm, and the misalignment is 1.2mm. The uniform preheating temperature is 135℃. The peak current of the first welding is 360A, the base current is 110A, and the wire feed speed is 6.0m / min. The second welding current is 250A. The third welding current is 230A. The post-heat treatment temperature is 235℃, and the holding time is 1.3h. The remaining process steps are the same as in Example 1.

[0068] Comparative Example 1: The basic content is the same as in Example 1, except that: In Comparative Example 1, step S2 is not performed. That is, after the first base material completes the first bevel processing, a weld layer is not formed on the first bevel. Instead, after the first base material and the second base material are assembled and preheated, the bevel area to be welded is directly subjected to first welding, second welding and third welding in sequence. All other process parameters are consistent with those in Example 1.

[0069] Comparative Example 2: The basic content is the same as in Example 1, except that: In Comparative Example 2, when forming the weld layer in step S2, ordinary MAG welding was used instead of pulsed MAG welding. Ordinary MAG welding was also used for the first welding. The remaining steps and process parameters were consistent with those in Example 1.

[0070] The following is a comparison of the data for Examples 1, 2, and 3, Comparative Example 1 and Comparative Example 2. Please refer to Table 1 for details.

[0071] Table 1 As shown in Table 1, the welded joints formed in Examples 1-3 all had a non-fusion length at the root of the groove controlled between 0.16-0.21 mm and a non-penetration depth controlled between 0.04-0.06 mm. In contrast, the non-fusion lengths of Comparative Examples 1 and 2 reached 0.86 mm and 0.53 mm, respectively, and the non-penetration depths reached 0.29 mm and 0.17 mm, respectively. This indicates that after adopting the welding method of this disclosure, the fusion state in the root region of the groove is more uniform, and the defects at the root of the groove are reduced.

[0072] Furthermore, as shown in Table 1, the airtightness leakage rates of the welded joints formed in Examples 1-3 are 7.6 × 10⁻⁶, respectively. -8 Pa·m 3 / s, 8.4×10 -8 Pa·m 3 / s and 6.8×10 -8 Pa·m 3 The leakage rates of Examples 1-3 were all lower than those of Comparative Examples 1 and 2. Furthermore, the airtightness test pass rates of Examples 1-3 were all 100%, higher than those of Comparative Examples 1 and 2. This indicates that by pre-forming a weld layer and allowing it to remelt during a single welding process to participate in the initial molten pool formation, the heat input process within the bevel welding area becomes more stable, reducing the possibility of continuous leakage channels forming at the bevel root, thus resulting in a lower leakage rate in the welded joint.

[0073] The comprehensive embodiments and comparative examples illustrate that, by pre-forming a weld layer and cooperating with the subsequent welding process, the bevel area to be welded forms an arc heat input process that differs from conventional welding processes. This is beneficial for improving the fusion state of the root region of the bevel, reducing root defects, and further improving the sealing reliability and welding stability of the welded joint.

[0074] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the following claims.

[0075] It should be understood that this disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims.

Claims

1. An arc welding method based on heat redistribution, characterized in that, The welding method specifically includes the following steps: Step S1: Machining is performed on the mating edges of the first and second base materials to obtain the corresponding first bevel and second bevel; Step S2: Use welding material to deposit a weld layer at the first bevel; Step S3: Assemble the first base material and the second base material so that the first bevel and the second bevel are joined to form a bevel welding area, and uniformly preheat the bevel welding area; wherein, the weld layer is located in the bevel welding area. Step S4: Perform a first weld on the bevel area to be welded to form an initial weld; then perform a second and third weld on the initial weld to form a complete weld; then perform post-heat treatment on the complete weld, and after the post-heat treatment is completed, the welded component is obtained.

2. The arc welding method based on heat redistribution according to claim 1, characterized in that, The first bevel and the second bevel are obtained according to the following steps: First, fix the first and second base materials in the machining fixture, and make the mating edges of the first and second base materials face the cutting tool respectively; then, use milling to cut the mating edges of the first base material to form an inclined bevel surface and a blunt edge, thus obtaining the first bevel; use milling to cut the mating edges of the second base material to form an inclined bevel surface and a blunt edge, thus obtaining the second bevel.

3. The arc welding method based on heat redistribution according to claim 1, characterized in that, In step S1, both the first base material and the second base material are any one of Q345R low alloy steel plate, Q355R low alloy steel plate, and Q370R low alloy steel plate, and the strength grade of the first base material is not lower than that of the second base material; the thickness of both the first base material and the second base material is 12-20mm; the welding material is a solid low alloy steel welding wire with a diameter of 1.0-1.2mm. Both the first and second bevels are single-sided V-shaped bevels; the bevel angles of both the first and second bevels are 55-65° and the blunt edges are 1.0-2.0mm.

4. The arc welding method based on heat redistribution according to claim 1, characterized in that, Step S2 specifically includes the following steps: Step S21: Fix the first base material after the first bevel is formed onto the welding fixture, and make the side wall of the bevel root of the first bevel face the welding gun. Step S22: The welding material is fed to the end of the welding torch through the wire feeding mechanism, and the electric arc is ignited at the first bevel. Step S23: Use pulsed MAG welding to melt the welding material and deposit the molten welding material on the root sidewall of the first bevel. Step S24: Control the welding torch to move along the length of the first bevel so that the molten welding material is continuously deposited along the length of the first bevel and forms a weld layer after solidification.

5. The arc welding method based on heat redistribution according to claim 4, characterized in that, In step S24, the weld layer is continuously distributed along the length of the first bevel, and the weld layer is located on the side wall of the bevel root of the first bevel and is set close to the root of the first bevel; the thickness of the weld layer is 0.4-0.8mm and the width is 2.0-4.0mm.

6. The arc welding method based on heat redistribution according to claim 4, characterized in that, In steps S23 to S24, the peak current for forming the weld layer is 220-280A, the base current is 40-80A, the pulse frequency is 80-120Hz, the pulse width is 2.0-4.0ms, the pulse duty cycle is 20-35%, the wire feed speed is 3.5-5.0m / min, the arc voltage is 19-23V, the welding speed is 180-260mm / min, and the shielding gas flow rate is 15-22L / min.

7. The arc welding method based on heat redistribution according to claim 1, characterized in that, Step S3 specifically includes the following steps: Step S31: Place the first base material with the weld layer and the second base material with the second bevel on the assembly fixture, and set the first bevel and the second bevel opposite each other; Step S32: Adjust the relative position between the first base material and the second base material so that the first bevel and the second bevel are joined to form a bevel welding area, and make the weld layer located in the bevel welding area; Step S33: Position and fix the first base material and the second base material, and control the root gap of the bevel welding area and the misalignment between the first base material and the second base material; Step S34: Preheat the bevel area to be welded evenly.

8. The arc welding method based on heat redistribution according to claim 7, characterized in that, In step S33, the root gap of the bevel welding area is 2.0-3.0mm, and the misalignment between the first base material and the second base material is 0.5-1.5mm. In step S34, the preheating temperature for uniform preheating is 100-140℃.

9. The arc welding method based on heat redistribution according to claim 1, characterized in that, Step S4 specifically includes the following steps: Step S41: Perform a single welding operation on the root area of ​​the groove to be welded using pulsed MAG welding, so that the welding material melts and enters the groove to be welded, and at the same time the weld layer remelts and solidifies to form the initial weld. Step S42: Use MAG welding to perform secondary welding on the initial weld, so that the welding material melts and deposits on the initial weld to form an intermediate welding area; Step S43: Perform three welding operations on the intermediate welding area using MAG welding, so that the welding material melts and deposits on the intermediate welding area to form a complete weld. Step S44: Perform post-heat treatment on the complete weld and the base material areas on both sides of the complete weld. After the post-heat treatment is completed, the welded component is obtained.

10. The arc welding method based on heat redistribution according to claim 9, characterized in that, In step S41, the peak current of the first welding operation is 300-380A, the base current is 80-120A, the pulse frequency is 90-150Hz, the pulse width is 3.0-5.0ms, the pulse duty cycle is 30-45%, the wire feed speed is 4.5-6.5m / min, the arc voltage is 22-26V, the welding speed is 180-260mm / min, and the shielding gas flow rate is 18-22L / min; the arc center of the first welding operation is offset by 0.3-0.5mm towards the first base material. In step S42, the welding current for the secondary welding is 200-260A, the arc voltage is 24-30V, the welding speed is 250-350mm / min, and the shielding gas flow rate is 18-22L / min. In step S43, the welding current for the three welding operations is 190-240A, the arc voltage is 23-28V, the welding speed is 260-360mm / min, and the shielding gas flow rate is 18-22L / min. In step S44, the temperature of the post-heat treatment is 200-240℃, and the time of the post-heat treatment is 0.5-1.5h.

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