Double-layer, double-pass GMAW welding method to suppress hot cracking defects in nickel-based welding wire

Abstract

This invention discloses a double-layer, double-pass GMAW welding method for suppressing hot cracking defects in nickel-based welding wire. The method involves creating a 60° V-groove between two weldments using a butt joint, with a 1.5mm-2mm gap between them. A GMAW arc is used as the welding heat source, with a welding wire diameter of 1.2mm and a wire extension of 12mm-15mm. The welding is performed in a double-layer, double-pass manner. Specifically, during the root pass welding, the welding current is 110A-120A, the welding voltage is 17V, and the welding speed is 0.15m / min-0.2m / min. For the cap pass welding, the welding current is 190A-200A, the welding voltage is 24V, and the welding speed is 0.3m / min-0.35m / min. The aforementioned welding current ensures sufficient penetration and prevents weld overheating, while the aforementioned welding voltage achieves good weld morphology and reduces spatter. Combined with the aforementioned welding speed, the corresponding welding heat input effectively prevents the formation of low-melting-point eutectics in the nickel-based welding wire molten pool, suppressing the initiation of welding hot cracks. This effectively inhibits the formation of hot cracks during nickel-based welding, improving weld formation quality and joint mechanical properties.

Description

Technical Field

[0001] This invention relates to the field of welding technology, and in particular to a double-layer, double-pass GMAW welding method for suppressing hot cracking defects in nickel-based welding wire. Background Technology

[0002] Nickel-based alloy welding wire has excellent corrosion resistance, cold crack resistance, and good low-temperature and high-temperature performance. It contains abundant high-quality metallurgical elements and can adapt to different base materials dilution rates. It can be used for welding nickel-based alloys, stainless steel, carbon steel, and dissimilar materials. Therefore, it has wide applications in aerospace, petrochemical, vehicle and shipbuilding and other fields.

[0003] However, nickel-based alloys have a single-phase austenitic structure. Impurities and low-melting-point substances in the weld tend to segregate and accumulate at grain boundaries, forming intergranular liquid films that cause cracking during solidification of the molten pool. Therefore, nickel-based welding wires have a high sensitivity to hot cracking. At the same time, due to the small temperature gradient between the solid and liquid phases of nickel-based alloys, solidification is faster and fluidity is lower. When welding medium and thick plates, incomplete penetration defects are prone to occur, resulting in greater stress at the weld toe and exacerbating crack propagation. In practical applications of nickel-based welding wires for butt welding of medium and thick plates, improper selection and handling of welding parameters, welding procedures, reserved gaps, and pre-weld preparations often lead to significant defects in the weld, failing to meet quality inspection requirements and ultimately affecting the production efficiency and economic benefits of the manufacturing unit.

[0004] To address the above issues, high-energy-density welding processes such as laser welding and electron beam welding are mainly used domestically and internationally. These processes utilize nickel-based welding wire for butt welding of medium-thick plates, effectively controlling the welding heat input to suppress hot cracking and ensuring complete penetration to avoid stress concentration, thus effectively suppressing hot cracking defects when welding nickel-based alloys. However, these high-energy-density welding processes are complex, the equipment is expensive, and their adaptability to actual automated welding production lines in enterprises is low, making large-scale promotion difficult. Summary of the Invention

[0005] To address some or all of the technical problems existing in the prior art, this invention provides a double-layer, double-pass GMAW welding method for suppressing hot cracking defects in nickel-based welding wire. During the welding process, it can prevent overheating of the weld, facilitate penetration, effectively suppress the generation of weld cracks, avoid the formation of large stress at the weld toe, and result in good product performance after welding.

[0006] The technical solution of the present invention is as follows:

[0007] This invention provides a double-layer, double-pass GMAW welding method for suppressing hot cracking defects in nickel-based welding wire. During welding, a butt joint is used with a 60° V-groove and a 1.5mm-2mm gap. A GMAW arc is used as the welding heat source. The welding wire diameter is 1.2mm, and the wire extension is 12mm-15mm. A double-layer, double-pass welding method is employed. Specifically, during the root pass welding, the welding current is 110A-120A, the welding voltage is 17V, and the welding speed is 0.15m / min-0.2m / min. For the cap pass welding, the welding current is 190A-200A, the welding voltage is 24V, and the welding speed is 0.3m / min-0.35m / min.

[0008] Furthermore, a shielding gas is introduced during the welding process, and the flow rate of the shielding gas is 20L / min-25L / min.

[0009] Furthermore, the protective gas is a mixture of 80% Ar and 20% CO2.

[0010] Furthermore, the material being welded is a 5mm-6mm thick plate of low-alloy high-strength steel.

[0011] Furthermore, spot welding is performed at both ends of the test plate to prevent incomplete penetration and defects caused by thermal expansion of the test plate, reduce stress concentration at the weld toe, and avoid the formation of weld crack sources.

[0012] The main advantages of the technical solution of this invention are as follows:

[0013] This invention discloses a double-layer, double-pass GMAW welding method for suppressing hot cracking defects in nickel-based welding wire. During welding, a butt joint is used, and a GMAW arc is employed as the welding heat source. For the root pass, the welding current is 110A-120A, the welding voltage is 17V, and the welding speed is 0.15m / min-0.2m / min. For the cap pass, the welding current is 190A-200A, the welding voltage is 24V, and the welding speed is 0.3m / min-0.35m / min. The double-layer, double-pass welding method employs different welding currents, voltages, and speeds for the root and cap passes. Within a certain range, the welding current achieves sufficient penetration and prevents weld overheating. Within a certain range, the welding voltage achieves good weld morphology and reduces spatter. Combined with a certain range of welding speeds, the corresponding heat input effectively avoids the formation of low-melting-point eutectics in the nickel-based welding wire molten pool, thus suppressing the formation of welding hot cracks. This effectively suppresses the generation of hot cracks during the welding process of nickel-based welding wire, and significantly improves the weld formation quality and the mechanical properties of the joint.

[0014] Furthermore, the double-layer double-pass GMAW welding method of the present invention for suppressing hot cracking defects of nickel-based welding wire can prevent incomplete penetration and defects caused by thermal expansion of the test plate by reserving a certain gap and fixing it by spot welding. It can effectively reduce stress concentration at the weld toe and avoid the formation of weld crack sources. Attached Figure Description

[0015] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and constitute a part of this invention, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0016] Figure 1 This is a schematic diagram of a double-layer, double-pass GMAW welding method for suppressing hot cracking defects in nickel-based welding wire according to an embodiment of the present invention.

[0017] Figure 2 This is a magnified schematic diagram of the welded surface of a sample after welding, provided by an embodiment of the present invention, using a double-layer, double-pass GMAW welding method to suppress hot cracking defects in nickel-based welding wire.

[0018] Figure 3 This is a magnified schematic diagram of the weld surface of a sample after welding, provided by an embodiment of the present invention, using a double-layer, double-pass GMAW welding method to suppress hot cracking defects in nickel-based welding wire.

[0019] Figure 4 The image shows the actual tensile test results of the specimens after welding using a double-layer double-pass GMAW welding method that suppresses hot cracking defects of nickel-based welding wire, as provided in an embodiment of the present invention, and a conventional welding method.

[0020] Figure 5 The image shows the actual tensile effect of a welded specimen and the original specimen after a tensile test, provided as an embodiment of the present invention.

[0021] Explanation of reference numerals in the attached figures:

[0022] 1. Sample; 2. Tooling fixture; 3. MAG welding torch; 4. Butt joint; 5. Bevel; 6. Horizontal pad. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0024] The technical solutions provided by the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0025] GMAW is an abbreviation for gas metal arc welding, which refers to gas metal arc welding. This welding process is one of the most widely used welding methods in various manufacturing industries due to its wide applicability, low cost, and high degree of automation. It effectively ensures product quality and production efficiency. It refers to a welding method that uses an electric arc generated between the welding wire and the workpiece as a heat source to melt metal. During the welding process, the molten pool formed by the arc melting the welding wire and the base metal, as well as the welding area, are protected by inert or reactive gases, effectively preventing the harmful effects of the surrounding ambient air.

[0026] As attached Figure 1-5 As shown, this embodiment of the invention provides a double-layer, double-pass GMAW welding method for suppressing hot cracking defects in nickel-based welding wires. The method includes:

[0027] Example 1

[0028] During welding, a butt joint is used, with a 60° V-groove cut between the two weldments, leaving a gap of 1.5mm-2mm between them. A GMAW arc is used as the welding heat source, with a welding wire diameter of 1.2mm and a wire extension of 12mm-15mm. A double-layer, double-pass welding method is adopted. Specifically, for the root pass welding, the welding current is 110A-120A, the welding voltage is 17V, and the welding speed is 0.15m / min-0.2m / min; for the cover pass welding, the welding current is 190A-200A, the welding voltage is 24V, and the welding speed is 0.3m / min-0.35m / min.

[0029] With this configuration, the double-layer, double-pass GMAW welding method of the present invention for suppressing hot cracking defects in nickel-based welding wire adopts different welding currents, welding voltages, and welding speeds for the root pass and the cover pass during welding. By setting the welding current within a certain range for the root pass and the cover pass in the above welding process, sufficient penetration depth can be obtained and overheating of the weld can be prevented. Setting the welding voltage within a certain range can obtain a good macroscopic weld morphology and reduce spatter. Combined with a welding speed within a certain range, the corresponding welding heat input can effectively avoid the generation of low-melting-point eutectic in the nickel-based welding wire molten pool and suppress the generation of welding hot cracks.

[0030] In some optional implementations of this embodiment, the welding current range is 110A-200A, the welding voltage is 17V-24V, and the welding flow rate is 0.15m / min-0.35m / min. To ensure welding effect and have wider application, the welding current can also be set to 80A-300A, the welding voltage can also be set to 10V-30V, and the welding flow rate can be 0.08m / min-0.5m / min, so that the welding parameters of the root pass and the top pass during the welding process are within the above parameter range, and the target welding effect is achieved.

[0031] It should also be noted that: before welding, a bevel is processed at the joint of the workpiece to be welded, and the area around the joint after processing is cleaned or ground. After the workpiece to be welded is cleaned, a certain gap is left before clamping it on the worktable.

[0032] Specifically, a shielding gas is introduced during the above welding process, and the flow rate of the shielding gas is 20L / min-25L / min.

[0033] Specifically, the protective gas is a mixture of 80% Ar and 20% CO2.

[0034] During welding, the use of 80% Ar gas serves several purposes. First, since metals readily react with oxygen in the air to form metal oxides, leading to a decline in weld quality, the introduction of Ar gas creates a protective atmosphere in the welding area, excluding oxygen from the air and effectively preventing oxidation. Simultaneously, the Ar gas envelops the welding area, forming a protective layer that protects the weld from environmental contaminants, resulting in higher weld purity and better weld quality. Second, the introduction of Ar gas effectively lowers the melting temperature in the welding area, reducing the influence of oxygen in the air and thus minimizing metal oxidation and deformation, thereby improving welding stability and precision. Furthermore, the introduction of Ar gas can enhance the arc... Stability is improved, spatter and jetting are reduced, making the welding process more controllable and stable. The use of 20% CO2 offers several advantages: firstly, CO2 is low-cost, reducing overall welding costs; secondly, carbon dioxide forms a protective layer during welding, isolating the weld and arc from the outside air and preventing oxidation and contamination from gases like oxygen and nitrogen; thirdly, CO2 gas is inexpensive and does not produce toxic gases or harmful substances, thus reducing environmental impact and minimizing weld porosity and slag inclusions; and fourthly, CO2 gas provides a higher energy density arc, resulting in faster welding speeds, which improves welding efficiency and shortens welding cycles for production lines with high welding volumes.

[0035] Using the above-mentioned 80%Ar+20%CO2 mixture as a shielding gas can ensure welding effect, prevent weld oxidation, reduce weld porosity, slag inclusions and other defects, reduce spatter and jetting, lower melting temperature, improve arc stability, and form an arc with higher energy density, making the welding process more reliable and efficient, reducing costs, enabling mass production, and shortening the welding cycle.

[0036] Specifically, the material being welded is a 5mm-6mm thick plate of low-alloy high-strength steel.

[0037] Specifically, spot welding is performed at both ends of the test plate to prevent incomplete penetration and defects caused by thermal expansion of the test plate, reduce stress concentration at the weld toe, and avoid the formation of weld crack sources.

[0038] In some optional implementations of this embodiment, the thickness of the welding material can also be 3mm-10mm, with different thicknesses of welding material...

[0039] In the above-mentioned spot welding process, the welding parameters within the above-mentioned root pass welding range are used to ensure the stability of welding heat input and weld metal filling amount, and to suppress the formation of welding hot cracks.

[0040] In some optional implementations of this embodiment, the GMAW welding equipment used in the welding process is a Panasonic YD-ABD35 digital welding machine and a Panasonic TAWERS-1400G3 welding robot. The welding torch's operating posture, welding torch movement trajectory, and welding parameters during the welding process are all directly set through the robot's panel.

[0041] In some optional implementations of this embodiment, after welding, a DK77 EDM CNC wire cutting machine is used to prepare a metallographic tensile specimen of the joint, and the macroscopic and metallographic cross-sectional morphology of the weld is photographed. The tensile properties of the specimen are then tested using a KY-100KNW universal testing machine.

[0042] Example 2

[0043] In some optional implementations of this embodiment, taking a 5mm Q345 low-alloy high-strength steel plate as an example, the welding is performed using the method described in Embodiment 1 above.

[0044] Specifically, when welding 5mm thick Q345 plates, first process a 60° V-shaped bevel at the joint of the workpiece to be welded, and then clean or grind the area around the joint after processing. After cleaning, clamp the workpiece to be welded on the workbench with a 1.5mm gap in mind and then perform the welding operation.

[0045] When performing welding, such as Figure 1As shown, the bevel 5 on the side of the butt joint 4 is pre-trimmed, and then the sample 1 is placed on the horizontal pad 6 and fixed with the tooling fixture 2. GMAW arc is used as the welding heat source, the welding wire diameter is 1.2mm and the wire extension is 12mm. MAG welding gun 3 is used for welding in a double-layer, double-pass welding method. During the root pass welding, the welding current is 110A, the welding voltage is 17V, and the welding speed is 0.15m / min; the cover pass welding current is 190A, the welding voltage is 24V, and the welding speed is 0.3m / min. During the welding process, a shielding gas mixture of 80% Ar + 20% CO2 is introduced at a flow rate of 20L / min. Spot welding is performed at both ends of the test plate to prevent incomplete penetration and defects caused by thermal expansion, reduce stress concentration at the weld toe, and avoid the formation of weld crack sources.

[0046] Example 3

[0047] In some optional implementations of this embodiment, taking a 6mm Q345 low-alloy high-strength steel plate as an example, the welding is performed using the method described in Embodiment 1 above.

[0048] Specifically, when welding 6mm thick Q345 plates, first process a 60° V-shaped bevel at the joint of the workpiece to be welded, and then clean or grind the area around the joint after processing. After cleaning, clamp the workpiece to be welded on the workbench with a 2mm gap in mind and then perform the welding operation.

[0049] When performing welding, such as Figure 1 As shown, the bevel 5 on the side of the butt joint 4 is pre-trimmed, and then the sample 1 is placed on the horizontal pad 6 and fixed with the tooling fixture 2. GMAW arc is used as the welding heat source, the welding wire diameter is 1.2mm and the wire extension is 12mm. MAG welding gun 3 is used for welding in a double-layer, double-pass welding method. During the root pass welding, the welding current is 120A, the welding voltage is 17V, and the welding speed is 0.2m / min; the cover pass welding current is 200A, the welding voltage is 24V, and the welding speed is 0.35m / min. During the welding process, a shielding gas mixture of 80% Ar + 20% CO2 is introduced at a flow rate of 25L / min. Spot welding is performed at both ends of the test plate to prevent incomplete penetration and defects caused by thermal expansion of the test plate, reduce stress concentration at the weld toe, and avoid the formation of weld crack sources.

[0050] In comparison, such as Figure 4 As shown, in Figure 4Two groups of samples marked L1 and two groups of samples marked L2 are shown in the figure. The first sample in the L1 group is a control sample (the first sample marked L1 from top to bottom in the figure), and the second sample is a tensile test performed after ordinary welding. The performance of the sample after ordinary welding is tested, and the tensile test results are shown in the figure. The first sample marked L2 (the first sample marked L2 from top to bottom in the figure) is another control sample. The second sample marked L2 is a sample welded using the method of this embodiment and subjected to the same tensile force as the sample marked L1. Tensile tests were performed on both groups of samples. Comparing the two groups of samples in Example 1 and the two groups of samples in Example 2, the samples welded by ordinary means showed no significant elongation in the tensile region during tensile testing, and no obvious necking phenomenon during the tensile process, resulting in direct fracture. However, the samples welded using the method described in Example 1 showed a significant increase in the length of the tensile region during tensile testing, and exhibited obvious necking phenomenon during the tensile process. Furthermore, the samples did not fracture under the same tensile force. Therefore, compared to the two methods, the samples welded using the method of this invention have better tensile properties and are superior to the overall performance of the samples welded by ordinary means.

[0051] In comparison, such as Figure 5 As shown, in Figure 5 Two groups of samples marked L1 and two groups of samples marked L2 are shown in the figure. The first sample in the L1 group is a control sample (the first sample marked L1 from top to bottom in the figure), and the second sample is a tensile test performed after ordinary welding to test the performance of the sample after ordinary welding. The first sample marked L2 (the first sample marked L2 from top to bottom in the figure) is another control sample, and the other sample marked L2 is the original sample. After being stretched with the same tensile force as the samples marked L1, both groups of samples were stretched. The two groups of samples with L1 and the two groups of samples with L2 were compared. The sample after ordinary welding showed no obvious elongation in the tensile region and no obvious necking phenomenon during the tensile process, and it broke directly. The tensile results of the original sample were basically consistent with the cross-section of the sample after ordinary welding.

[0052] Overall, through Figure 4 and Figure 5 After tensile testing, the specimen was welded using the double-layer, double-pass GMAW welding method of the present invention to suppress hot cracking defects in nickel-based welding wire. The welded surface was as follows: Figure 2 As shown, the weld fusion line after welding is as follows: Figure 3As shown, the surface after welding is smooth, the contact between the weld and the sample is good, flat, and without cracks; thus, the performance of the welded sample is better than that of the original sample and the ordinary sample, indicating that the method of the present invention can easily penetrate the weld, effectively suppress the generation of weld cracks, avoid the formation of large stress at the weld toe, and result in good product performance after welding.

[0053] A butt joint was adopted, using a GMAW arc as the welding heat source. For the root pass, the welding current was 110A-120A, the welding voltage was 17V, and the welding speed was 0.15m / min-0.2m / min. For the cap pass, the welding current was 190A-200A, the welding voltage was 24V, and the welding speed was 0.3m / min-0.35m / min. A double-pass, double-layer welding method was used for the root and cap passes, employing different welding currents, voltages, and speeds. Within a certain range, the welding current achieved sufficient penetration and prevented weld overheating. Within a certain range, the welding voltage achieved good weld morphology and reduced spatter. Combined with a certain range of welding speeds, the corresponding heat input effectively avoided the formation of low-melting-point eutectics in the nickel-based welding wire molten pool, suppressing the initiation of welding hot cracks. This effectively suppressed the formation of hot cracks during the welding process of nickel-based welding wire, significantly improving weld formation quality and joint mechanical properties.

[0054] Furthermore, the double-layer double-pass GMAW welding method of the present invention for suppressing hot cracking defects of nickel-based welding wire can prevent incomplete penetration and defects caused by thermal expansion of the test plate by reserving a certain gap and fixing it by spot welding. It can effectively reduce stress concentration at the weld toe and avoid the formation of weld crack sources.

[0055] In summary, the present invention provides a double-layer, double-pass GMAW welding method for suppressing hot cracking defects in nickel-based welding wire. During welding, a butt joint is used, and a GMAW arc is employed as the welding heat source. For the root pass, the welding current is 110A-120A, the welding voltage is 17V, and the welding speed is 0.15m / min-0.2m / min. For the cap pass, the welding current is 190A-200A, the welding voltage is 24V, and the welding speed is 0.3m / min-0.35m / min. By employing different welding currents, voltages, and speeds for the root and cap passes, a double-layer, double-pass welding method is used. Within a certain range, the welding current achieves sufficient penetration and prevents weld overheating. Within a certain range, the welding voltage achieves good weld morphology and reduces spatter. Combined with a certain range of welding speeds, the corresponding welding heat input effectively avoids the formation of low-melting-point eutectics in the nickel-based welding wire molten pool, thus suppressing the formation of welding hot cracks. This effectively suppresses the formation of hot cracks during the welding process of nickel-based welding wire, significantly improving the weld formation quality and the mechanical properties of the joint. Simultaneously, by reserving a certain gap and fixing it using spot welding, it prevents incomplete penetration and other defects caused by thermal expansion of the test plate, effectively reducing stress concentration at the weld toe and avoiding the formation of weld crack initiation points.

[0056] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Additionally, the terms "front," "back," "left," "right," "upper," and "lower" in this document refer to the placement shown in the accompanying drawings.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A double-layer, double-pass GMAW welding method for suppressing hot cracking defects in nickel-based welding wire, characterized in that, During welding, a butt joint is used, with a 60° V-groove cut between the two weldments, leaving a gap of 1.5mm-2mm between them. A GMAW arc is used as the welding heat source, with a welding wire diameter of 1.2mm and a wire extension of 12mm-15mm. A double-layer, double-pass welding method is employed. For the root pass, the welding current is 110A-120A, the welding voltage is 17V, and the welding speed is 0.15m / min-0.2m / min. For the cover pass, the welding current is 190A-200A, the welding voltage is 24V, and the welding speed is 0.3m / min-0.35m / min. The material being welded is a 5mm-6mm thick plate of low-alloy high-strength steel; The two-layer, two-pass welding method, using different welding currents, welding voltages, and welding speeds for the base layer and the cover layer, effectively avoids the formation of low-melting-point eutectics in the nickel-based welding wire molten pool and suppresses the generation of welding hot cracks.

2. The double-layer, double-pass GMAW welding method for suppressing hot cracking defects in nickel-based welding wire according to claim 1, characterized in that, During the welding process, a shielding gas is introduced, and the flow rate of the shielding gas is 20L / min-25L / min.

3. The double-layer, double-pass GMAW welding method for suppressing hot cracking defects in nickel-based welding wire according to claim 1, characterized in that, The protective gas is a mixture of 80% Ar and 20% CO2.

4. The double-layer, double-pass GMAW welding method for suppressing hot cracking defects in nickel-based welding wire according to claim 1, characterized in that, Spot welding is performed at both ends of the test plate to prevent incomplete penetration and defects caused by thermal expansion of the test plate, reduce stress concentration at the weld toe, and avoid the formation of weld crack sources.

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