Method for eliminating carbon enrichment in transition zone of dissimilar metal argon arc welding joint and application

Abstract

The application discloses a method for eliminating carbon enrichment in a transition zone of a welded joint of dissimilar metal argon arc welding and application, and belongs to the technical field of dissimilar metal welding. The method comprises the following steps: processing and cleaning a base metal groove, welding 617 nickel-based alloy welding wire on the surface of a 321 austenitic stainless steel plate with a processed groove through a manual argon arc welding process; processing and cleaning the 321 austenitic stainless steel plate, assembling the 321 austenitic stainless steel plate and a 617 nickel-based alloy plate, and fixing the two ends; and finally, assembling and welding the assembled and fixed alloy plates by adopting a tungsten inert gas argon arc welding process. The selected 617 nickel-based alloy welding wire is ERNiCrCoMo-1, and the diameter is 0.8mm-2.4mm. The application can effectively eliminate the carbon enrichment phenomenon in the transition zone of the welded joint of the 321 austenitic stainless steel and the 617 nickel-based alloy dissimilar metal, thereby improving the performance of the welded joint of the dissimilar metal; and the application is simple to operate, low in cost and convenient and flexible.

Description

Technical Field

[0001] This invention belongs to the field of dissimilar metal welding technology, specifically relating to a method and application for eliminating carbon enrichment in the transition zone of dissimilar metal argon arc welding joints. Background Technology

[0002] With the rapid development of my country's nuclear industry, the amount of spent fuel accumulating is becoming increasingly large, and the development and application of spent fuel reprocessing technology has gradually become a research hotspot in the nuclear energy field. The wet reprocessing process (PULEX process) is one of the spent fuel reprocessing technologies that my country is currently focusing on developing. The high-carbon material combustion system, as one of the key pieces of equipment, converts carbon in high-carbon materials into gas through combustion, achieving fuel volume reduction and thus recovering metal oxides from the fuel. 617 nickel-based alloy is a key material for the main equipment manufacturing; however, considering economic factors, some internal components, cyclone separators, pumps, valves, and other process equipment and pipelines are made of 321 austenitic stainless steel. The two materials differ significantly in composition, microstructure, and physicochemical properties, making the dissimilar metal welded joint a weak point in the structure. In particular, carbon migration and the formation of carbon-rich areas in the transition zone occur during welding, posing a significant risk to the long-term safe operation of the equipment.

[0003] The formation of a carbon-enriched transition zone in dissimilar metal weld joints is caused by the difference in carbon activity between the base metal and the weld metal. Studies have shown that when the carbon activity in the base metal is greater than that in the weld metal, carbon atoms will spontaneously diffuse and migrate from the base metal side to the weld side at the high temperature stage of welding, even if the time is short, forming a carbon-rich layer of a certain width. Compared with 321 austenitic stainless steel, 617 nickel-based alloy has a slightly lower carbon activity, thus resulting in a carbon-enriched region in the weld joint. Chinese patent CN117415489A discloses an ultrasonic-assisted welding method for thin plates of dissimilar metals such as nickel-based alloys and stainless steel. By adjusting the ultrasonic power and current to control the intensity of molten pool vibration and the size of the arc, the flow of the molten pool is enhanced, allowing for more thorough element mixing and reducing the sharp rise and fall of element content at the joint. However, this method is only suitable for thin plates with a thickness of 1mm-2mm. When the plate is thicker, it will hinder the propagation of ultrasonic energy and will not have a beneficial effect. Chinese patent CN115255599A discloses a welding method for nickel-based superalloys and austenitic stainless steel, but this method requires pressurization and heat preservation under vacuum conditions, making it difficult to widely use in the connection of large-scale engineering structures. Furthermore, while the aforementioned prior art can achieve the welding of nickel-based alloys and austenitic stainless steel, it does not address how to solve the problem of carbon enrichment in the transition zone. Summary of the Invention

[0004] To address the problem of carbon enrichment in the transition zone of dissimilar metal welded joints of 321 austenitic stainless steel and 617 nickel-based alloy, which affects the performance of the welded joint, this invention aims to provide a method for eliminating carbon enrichment in the transition zone of dissimilar metal argon arc welding joints. By selecting appropriate 617 nickel-based alloy welding wire and welding process conditions, and employing an argon arc welding process with low welding heat input, a 617 nickel-based alloy isolation layer is prepared on the bevel surface of the 321 austenitic stainless steel, and then welded to the 617 nickel-based alloy joint. This eliminates the carbon enrichment phenomenon in the transition zone, improves the performance of the welded joint, and extends its service life.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] In a first aspect, the present invention provides a method for eliminating carbon enrichment in the transition zone of a dissimilar metal argon arc welding joint, comprising the following steps:

[0007] Beveling of base material: Beveling is performed on the base material 321 austenitic stainless steel plate and 617 nickel-based alloy plate respectively, and the bevel surface is cleaned to remove oil stains;

[0008] 617 nickel-based alloy isolation layer: By adjusting the welding process parameters of manual argon arc welding, 617 nickel-based alloy welding wire is deposited on the surface of 321 austenitic stainless steel plate with a pre-grooved groove to form a 617 nickel-based alloy isolation layer.

[0009] Re-beveling, assembly and spot welding: After overlaying the 617 nickel-based alloy isolation layer, the 321 austenitic stainless steel plate is beveled again, the thickness of the 617 nickel-based alloy isolation layer is controlled, the bevel surface is cleaned to remove oil stains, and then it is assembled with the 617 nickel-based alloy plate and spot welded at both ends for fixation.

[0010] Assembled welding: The 321 austenitic stainless steel plate and 617 nickel-based alloy plate are assembled and tack-welded using tungsten inert gas (TIG) welding. The TIG welding process parameters are adjusted to complete the welding.

[0011] Furthermore, in the beveling process of the base material, the 321 austenitic stainless steel plate and the 617 nickel-based alloy plate are processed into a single-sided V-shaped bevel with a bevel angle of 27.5°, and the bevel surface is cleaned with acetone and alcohol.

[0012] Furthermore, in the 617 nickel-based alloy isolation layer, the 617 nickel-based alloy welding wire is grade ERNiCrCoMo-1 with a diameter of 0.8mm-2.4mm.

[0013] Furthermore, in the 617 nickel-based alloy isolation layer, the welding process parameters for manual argon arc welding are: current 80A-120A, voltage 8V-12V, welding speed 1.5mm / s-2.0mm / s, shielding gas argon purity ≥99.999%, and gas flow rate 10L / min-20L / min.

[0014] Furthermore, during the re-beveling, assembly, and spot welding, the 321 austenitic stainless steel plate was re-processed into a single-sided V-shaped bevel with a bevel angle of 27.5°. After re-beveling, the thickness of the 617 nickel-based alloy isolation layer was controlled to be ≥3mm. The bevel surface was cleaned with acetone and alcohol.

[0015] Furthermore, in the assembly welding, the process parameters for tungsten inert gas (TIG) argon arc welding are: current 120A-125A, voltage 12V-13V, welding speed 120mm / min-125mm / min, shielding gas argon purity ≥99.999%, and gas flow rate 10L / min-20L / min.

[0016] Secondly, this invention provides an application of a method for eliminating carbon enrichment in the transition zone of dissimilar metal argon arc welding joints, used for dissimilar metal welding of 617 nickel-based alloy and 321 austenitic stainless steel in the fields of nuclear power and chemical industry.

[0017] Advantages and effects of the present invention:

[0018] This invention employs a low-heat-input argon arc welding process, pre-preparing a 617 nickel-based alloy isolation layer on the bevel surface of 321 austenitic stainless steel. Combined with the ERNiCrCoMo-1 welding wire selected in this invention, it effectively eliminates carbon enrichment in the transition zone of the dissimilar metal weld joint between 321 austenitic stainless steel and 617 nickel-based alloy, thereby improving the performance of the weld joint. This invention is simple to operate, low in cost, convenient and flexible, and has a wide range of applications, particularly in the fields of nuclear power and chemical engineering. Attached Figure Description

[0019] Figure 1 The images are electron probe microscopy images of the transition zone of a dissimilar metal welded joint after the carbon enrichment in the transition zone was eliminated using the method described in Example 1. (a) is a microstructure diagram, and (b) is a carbon element distribution diagram.

[0020] Figure 2 The images are electron probe microscopy images of the transition zone of a dissimilar metal welded joint after the carbon enrichment in the transition zone was eliminated using the method described in Example 2. (a) is a microstructure diagram, and (b) is a carbon element distribution diagram.

[0021] Figure 3The images are electron probe microscopy images of the transition zone of the dissimilar metal welded joint after the carbon enrichment in the transition zone was eliminated using the method described in Example 3. (a) is a microstructure diagram, and (b) is a carbon element distribution diagram.

[0022] Figure 4 The images are electron probe microscopy images of the transition zone of a dissimilar metal welded joint after the carbon enrichment in the transition zone was eliminated using the method described in Example 4. (a) is a microstructure diagram, and (b) is a carbon element distribution diagram.

[0023] Figure 5 The images are electron probe microscopy images of the transition zone of a dissimilar metal welded joint after the carbon enrichment in the transition zone was eliminated using the method described in Example 5. (a) is a microstructure diagram, and (b) is a carbon element distribution diagram.

[0024] Figure 6 The images are electron probe microscopy images of the transition zone of a dissimilar metal welded joint after the carbon enrichment in the transition zone was eliminated using the method described in Example 6. (a) is a microstructure diagram, and (b) is a carbon element distribution diagram.

[0025] Figure 7 The images are electron probe microscopy images of the transition zone of a dissimilar metal welded joint after the carbon enrichment in the transition zone was eliminated using the method described in Example 7. (a) is a microstructure diagram, and (b) is a carbon element distribution diagram.

[0026] Figure 8 The images are electron probe microscopy images of the transition zone of a dissimilar metal welded joint after the carbon enrichment in the transition zone was eliminated using the method described in Example 8. (a) is a microstructure diagram, and (b) is a carbon element distribution diagram.

[0027] Figure 9 The images shown are electron probe microscopy images of the transition zone of the dissimilar metal welded joint in Comparative Example 1, where (a) is a microstructure diagram and (b) is a carbon element distribution diagram. Detailed Implementation

[0028] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples.

[0029] A method for eliminating carbon enrichment in the transition zone of a dissimilar metal argon arc welding joint includes the following steps:

[0030] Base material beveling: Beveling is performed on the 321 austenitic stainless steel plate and 617 nickel-based alloy plate respectively to form a single-sided V-shaped bevel with a bevel angle of 27.5°. The bevel surface is cleaned with acetone and alcohol to remove oil stains.

[0031] 617 nickel-based alloy isolation layer: The welding process parameters of manual TIG welding are controlled as follows: current 80A-120A, voltage 8V-12V, welding speed 1.5mm / s-2.0mm / s, shielding gas argon purity ≥99.999%, gas flow rate 10L / min-20L / min. 617 nickel-based alloy welding wire of grade ERNiCrCoMo-1 is welded onto the surface of a beveled 321 austenitic stainless steel plate. The diameter of the welding wire is 0.8mm-2.4mm to form a 617 nickel-based alloy isolation layer.

[0032] Second beveling, assembly and spot welding: After the 617 nickel-based alloy isolation layer is overlaid, the 321 austenitic stainless steel plate is beveled again to form a single-sided V-shaped bevel with a bevel angle of 27.5°. The thickness of the 617 nickel-based alloy isolation layer is controlled to be ≥3mm. The bevel surface is cleaned with acetone and alcohol to remove oil stains. Then it is assembled with the 617 nickel-based alloy plate and spot welded at both ends for fixation.

[0033] Assembled welding: Using tungsten inert gas (TIG) welding, the assembled and tack-bonded 321 austenitic stainless steel plate and 617 nickel-based alloy plate are assembled and welded. The TIG welding process parameters are adjusted as follows: current 120A-125A, voltage 12V-13V, welding speed 120mm / min-125mm / min, shielding gas argon purity ≥99.999%, and gas flow rate 10L / min-20L / min to complete the welding.

[0034] Example 1

[0035] A method for eliminating carbon enrichment in the transition zone of a dissimilar metal argon arc welding joint includes the following steps:

[0036] Beveling of base material: Beveling is performed on the base material 321 austenitic stainless steel plate (material size 250mm×150mm×12mm) and 617 nickel-based alloy plate (material size 250mm×150mm×12mm) to form a single-sided V-shaped bevel with a bevel angle of 27.5°. The bevel surface is cleaned with acetone and alcohol to remove oil stains.

[0037] 617 nickel-based alloy isolation layer: The manual argon arc welding method is adopted. The welding process parameters of manual argon arc welding are: current 90A, voltage 8V-10V, welding speed 1.6mm / s, shielding gas argon purity 99.999%, gas flow rate 15L / min. 617 nickel-based alloy welding wire (1mm in diameter) of grade ERNiCrCoMo-1 is welded onto the surface of 321 austenitic stainless steel plate with a bevel to form a 617 nickel-based alloy isolation layer.

[0038] Second beveling, assembly and spot welding: After the 617 nickel-based alloy isolation layer is overlaid, the 321 austenitic stainless steel plate is beveled again to form a single-sided V-shaped bevel with a bevel angle of 27.5°. The thickness of the 617 nickel-based alloy isolation layer is controlled to be ≥3mm. The bevel surface is cleaned with acetone and alcohol to remove oil stains. Then it is assembled with the 617 nickel-based alloy plate and spot welded at both ends for fixation.

[0039] Assembled welding: The 321 austenitic stainless steel plate and 617 nickel-based alloy plate were assembled and tack-welded using tungsten inert gas (TIG) welding. The TIG welding process parameters were: current 120A, voltage 12V, welding speed 120mm / min, shielding gas argon purity 99.999%, and gas flow rate 10L / min.

[0040] After welding, the cross-section of the weld joint was cut using an electric discharge wire cutter. After electrolytic etching with aqua regia and oxalic acid, a metallographic sample of the weld joint cross-section was prepared. The microstructure and carbon element distribution were characterized using a field emission electron probe microanalyzer (model JXA-iHP200F). Four locations were randomly tested, such as... Figure 1 The microstructure shown in (a) indicates that a transition zone (the area indicated by the dashed line in the figure) still exists in the dissimilar metal welded joint, but no carbon enrichment is observed in the transition zone. Figure 1 (b) The carbon element distribution diagram is shown.

[0041] Example 2

[0042] A method for eliminating carbon enrichment in the transition zone of a dissimilar metal argon arc welding joint includes the following steps:

[0043] Beveling of base material: Beveling is performed on the base material 321 austenitic stainless steel plate (material size 250mm×150mm×12mm) and 617 nickel-based alloy plate (material size 250mm×150mm×12mm) to form a single-sided V-shaped bevel with a bevel angle of 27.5°. The bevel surface is cleaned with acetone and alcohol to remove oil stains.

[0044] 617 nickel-based alloy isolation layer: The manual argon arc welding method is adopted. The welding process parameters of manual argon arc welding are: current 105A, voltage 9V-10V, welding speed 1.8mm / s, shielding gas argon purity 99.999%, gas flow rate 15L / min. 617 nickel-based alloy welding wire (1mm in diameter) of grade ERNiCrCoMo-1 is welded onto the surface of 321 austenitic stainless steel plate with a bevel to form a 617 nickel-based alloy isolation layer.

[0045] Second beveling, assembly and spot welding: After the 617 nickel-based alloy isolation layer is overlaid, the 321 austenitic stainless steel plate is beveled again to form a single-sided V-shaped bevel with a bevel angle of 27.5°. The thickness of the 617 nickel-based alloy isolation layer is controlled to be ≥3mm. The bevel surface is cleaned with acetone and alcohol to remove oil stains. Then it is assembled with the 617 nickel-based alloy plate and spot welded at both ends for fixation.

[0046] Assembled welding: The 321 austenitic stainless steel plate and 617 nickel-based alloy plate were assembled and tack-welded using tungsten inert gas (TIG) welding. The TIG welding process parameters were: current 123A, voltage 12.5V, welding speed 123mm / min, shielding gas argon purity 99.999%, and gas flow rate 15L / min.

[0047] After welding, the cross-section of the weld joint was cut using an electric discharge wire cutter. After electrolytic etching with aqua regia and oxalic acid, a metallographic sample of the weld joint cross-section was prepared. The microstructure and carbon element distribution were characterized using a field emission electron probe microanalyzer (model JXA-iHP200F). Four locations were randomly tested, such as... Figure 2 The microstructure shown in (a) indicates that a transition zone (the area indicated by the dashed line in the figure) still exists in the dissimilar metal welded joint, but no carbon enrichment is observed in the transition zone. Figure 2 (b) The carbon element distribution diagram is shown.

[0048] Example 3

[0049] A method for eliminating carbon enrichment in the transition zone of a dissimilar metal argon arc welding joint includes the following steps:

[0050] Beveling of base material: Beveling is performed on the base material 321 austenitic stainless steel plate (material size 250mm×150mm×12mm) and 617 nickel-based alloy plate (material size 250mm×150mm×12mm) to form a single-sided V-shaped bevel with a bevel angle of 27.5°. The bevel surface is cleaned with acetone and alcohol to remove oil stains.

[0051] 617 nickel-based alloy isolation layer: The manual argon arc welding method is adopted. The welding process parameters of manual argon arc welding are: current 120A, voltage 10V-11V, welding speed 1.6mm / s, shielding gas argon purity 99.999%, gas flow rate 15L / min. 617 nickel-based alloy welding wire (1mm in diameter) of grade ERNiCrCoMo-1 is welded onto the surface of 321 austenitic stainless steel plate with a bevel to form a 617 nickel-based alloy isolation layer.

[0052] Second beveling, assembly and spot welding: After the 617 nickel-based alloy isolation layer is overlaid, the 321 austenitic stainless steel plate is beveled again to form a single-sided V-shaped bevel with a bevel angle of 27.5°. The thickness of the 617 nickel-based alloy isolation layer is controlled to be ≥3mm. The bevel surface is cleaned with acetone and alcohol to remove oil stains. Then it is assembled with the 617 nickel-based alloy plate and spot welded at both ends for fixation.

[0053] Assembled welding: The 321 austenitic stainless steel plate and 617 nickel-based alloy plate were assembled and tack-welded using tungsten inert gas (TIG) welding. The TIG welding process parameters were: current 125A, voltage 13V, welding speed 125mm / min, shielding gas argon purity 99.999%, and gas flow rate 20L / min.

[0054] After welding, the cross-section of the weld joint was cut using an electric discharge wire cutter. After electrolytic etching with aqua regia and oxalic acid, a metallographic sample of the weld joint cross-section was prepared. The microstructure and carbon element distribution were characterized using a field emission electron probe microanalyzer (model JXA-iHP200F). Four locations were randomly tested, such as... Figure 3 The microstructure shown in (a) indicates that a transition zone (the area indicated by the dashed line in the figure) still exists in the dissimilar metal welded joint, but no carbon enrichment is observed in the transition zone. Figure 3 (b) The carbon element distribution diagram is shown.

[0055] Example 4

[0056] A method for eliminating carbon enrichment in the transition zone of a dissimilar metal argon arc welding joint includes the following steps:

[0057] Beveling of base material: Beveling is performed on the base material 321 austenitic stainless steel plate (material size 250mm×150mm×12mm) and 617 nickel-based alloy plate (material size 250mm×150mm×12mm) to form a single-sided V-shaped bevel with a bevel angle of 27.5°. The bevel surface is cleaned with acetone and alcohol to remove oil stains.

[0058] 617 nickel-based alloy isolation layer: The manual argon arc welding method is adopted. The welding process parameters of manual argon arc welding are: current 80A, voltage 8V-10V, welding speed 1.6mm / s, shielding gas argon purity 99.999%, gas flow rate 10L / min. 617 nickel-based alloy welding wire (1mm in diameter) of grade ERNiCrCoMo-1 is welded onto the surface of 321 austenitic stainless steel plate with a bevel to form a 617 nickel-based alloy isolation layer.

[0059] Second beveling, assembly and spot welding: After the 617 nickel-based alloy isolation layer is overlaid, the 321 austenitic stainless steel plate is beveled again to form a single-sided V-shaped bevel with a bevel angle of 27.5°. The thickness of the 617 nickel-based alloy isolation layer is controlled to be ≥3mm. The bevel surface is cleaned with acetone and alcohol to remove oil stains. Then it is assembled with the 617 nickel-based alloy plate and spot welded at both ends for fixation.

[0060] Assembled welding: The 321 austenitic stainless steel plate and 617 nickel-based alloy plate were assembled and tack-welded using tungsten inert gas (TIG) welding. The TIG welding process parameters were: current 121A, voltage 12.1V, welding speed 120mm / min, shielding gas argon purity 99.999%, and gas flow rate 15L / min.

[0061] After welding, the cross-section of the weld joint was cut using an electric discharge wire cutter. After electrolytic etching with aqua regia and oxalic acid, a metallographic sample of the weld joint cross-section was prepared. The microstructure and carbon element distribution were characterized using a field emission electron probe microanalyzer (model JXA-iHP200F). Four locations were randomly tested, such as... Figure 4 The microstructure shown in (a) indicates that a transition zone (the area indicated by the dashed line in the figure) still exists in the dissimilar metal welded joint, but no carbon enrichment is observed in the transition zone. Figure 4 (b) The carbon element distribution diagram is shown.

[0062] Example 5

[0063] A method for eliminating carbon enrichment in the transition zone of a dissimilar metal argon arc welding joint includes the following steps:

[0064] Beveling of base material: Beveling is performed on the base material 321 austenitic stainless steel plate (material size 250mm×150mm×12mm) and 617 nickel-based alloy plate (material size 250mm×150mm×12mm) to form a single-sided V-shaped bevel with a bevel angle of 27.5°. The bevel surface is cleaned with acetone and alcohol to remove oil stains.

[0065] 617 nickel-based alloy isolation layer: The manual argon arc welding method is adopted. The welding process parameters of manual argon arc welding are: current 120A, voltage 12V, welding speed 1.6mm / s, shielding gas argon purity 99.999%, gas flow rate 15L / min. 617 nickel-based alloy welding wire (1mm in diameter) of grade ERNiCrCoMo-1 is welded onto the surface of 321 austenitic stainless steel plate with a bevel to form a 617 nickel-based alloy isolation layer.

[0066] Second beveling, assembly and spot welding: After the 617 nickel-based alloy isolation layer is overlaid, the 321 austenitic stainless steel plate is beveled again to form a single-sided V-shaped bevel with a bevel angle of 27.5°. The thickness of the 617 nickel-based alloy isolation layer is controlled to be ≥3mm. The bevel surface is cleaned with acetone and alcohol to remove oil stains. Then it is assembled with the 617 nickel-based alloy plate and spot welded at both ends for fixation.

[0067] Assembled welding: The 321 austenitic stainless steel plate and 617 nickel-based alloy plate were assembled and tack-welded using tungsten inert gas (TIG) welding. The TIG welding process parameters were: current 125A, voltage 13V, welding speed 121mm / min, shielding gas argon purity 99.999%, and gas flow rate 15L / min.

[0068] After welding, the cross-section of the weld joint was cut using an electric discharge wire cutter. After electrolytic etching with aqua regia and oxalic acid, a metallographic sample of the weld joint cross-section was prepared. The microstructure and carbon element distribution were characterized using a field emission electron probe microanalyzer (model JXA-iHP200F). Four locations were randomly tested, such as... Figure 5 The microstructure shown in (a) indicates that a transition zone (the area indicated by the dashed line in the figure) still exists in the dissimilar metal welded joint, but no carbon enrichment is observed in the transition zone. Figure 5 (b) The carbon element distribution diagram is shown.

[0069] Example 6

[0070] A method for eliminating carbon enrichment in the transition zone of a dissimilar metal argon arc welding joint includes the following steps:

[0071] Beveling of base material: Beveling is performed on the base material 321 austenitic stainless steel plate (material size 250mm×150mm×12mm) and 617 nickel-based alloy plate (material size 250mm×150mm×12mm) to form a single-sided V-shaped bevel with a bevel angle of 27.5°. The bevel surface is cleaned with acetone and alcohol to remove oil stains.

[0072] 617 nickel-based alloy isolation layer: The manual argon arc welding method is adopted. The welding process parameters of manual argon arc welding are: current 90A, voltage 8V-10V, welding speed 1.5mm / s, shielding gas argon purity 99.999%, gas flow rate 20L / min. 617 nickel-based alloy welding wire (1mm in diameter) of grade ERNiCrCoMo-1 is welded onto the surface of 321 austenitic stainless steel plate with a bevel to form a 617 nickel-based alloy isolation layer.

[0073] Second beveling, assembly and spot welding: After the 617 nickel-based alloy isolation layer is overlaid, the 321 austenitic stainless steel plate is beveled again to form a single-sided V-shaped bevel with a bevel angle of 27.5°. The thickness of the 617 nickel-based alloy isolation layer is controlled to be ≥3mm. The bevel surface is cleaned with acetone and alcohol to remove oil stains. Then it is assembled with the 617 nickel-based alloy plate and spot welded at both ends for fixation.

[0074] Assembled welding: The 321 austenitic stainless steel plate and 617 nickel-based alloy plate were assembled and tack-welded using tungsten inert gas (TIG) welding. The TIG welding process parameters were: current 124A, voltage 12.8V, welding speed 122mm / min, shielding gas argon purity 99.999%, and gas flow rate 20L / min.

[0075] After welding, the cross-section of the weld joint was cut using an electric discharge wire cutter. After electrolytic etching with aqua regia and oxalic acid, a metallographic sample of the weld joint cross-section was prepared. The microstructure and carbon element distribution were characterized using a field emission electron probe microanalyzer (model JXA-iHP200F). Four locations were randomly tested, such as... Figure 6 The microstructure shown in (a) indicates that a transition zone (the area indicated by the dashed line in the figure) still exists in the dissimilar metal welded joint, but no carbon enrichment is observed in the transition zone. Figure 6 (b) The carbon element distribution diagram is shown.

[0076] Example 7

[0077] A method for eliminating carbon enrichment in the transition zone of a dissimilar metal argon arc welding joint includes the following steps:

[0078] Beveling of base material: Beveling is performed on the base material 321 austenitic stainless steel plate (material size 250mm×150mm×12mm) and 617 nickel-based alloy plate (material size 250mm×150mm×12mm) to form a single-sided V-shaped bevel with a bevel angle of 27.5°. The bevel surface is cleaned with acetone and alcohol to remove oil stains.

[0079] 617 nickel-based alloy isolation layer: The manual argon arc welding method is adopted. The welding process parameters of manual argon arc welding are: current 105A, voltage 9V-10V, welding speed 2.0mm / s, shielding gas argon purity 99.999%, gas flow rate 15L / min. 617 nickel-based alloy welding wire (0.8mm in diameter) of grade ERNiCrCoMo-1 is welded onto the surface of 321 austenitic stainless steel plate with a bevel to form a 617 nickel-based alloy isolation layer.

[0080] Second beveling, assembly and spot welding: After the 617 nickel-based alloy isolation layer is overlaid, the 321 austenitic stainless steel plate is beveled again to form a single-sided V-shaped bevel with a bevel angle of 27.5°. The thickness of the 617 nickel-based alloy isolation layer is controlled to be ≥3mm. The bevel surface is cleaned with acetone and alcohol to remove oil stains. Then it is assembled with the 617 nickel-based alloy plate and spot welded at both ends for fixation.

[0081] Assembled welding: The 321 austenitic stainless steel plate and 617 nickel-based alloy plate were assembled and tack-welded using tungsten inert gas (TIG) welding. The TIG welding process parameters were: current 122A, voltage 12.3V, welding speed 124mm / min, shielding gas argon purity 99.999%, and gas flow rate 15L / min.

[0082] After welding, the cross-section of the weld joint was cut using an electric discharge wire cutter. After electrolytic etching with aqua regia and oxalic acid, a metallographic sample of the weld joint cross-section was prepared. The microstructure and carbon element distribution were characterized using a field emission electron probe microanalyzer (model JXA-iHP200F). Four locations were randomly tested, such as... Figure 7 The microstructure shown in (a) indicates that a transition zone (the area indicated by the dashed line in the figure) still exists in the dissimilar metal welded joint, but no carbon enrichment is observed in the transition zone. Figure 7 (b) The carbon element distribution diagram is shown.

[0083] Example 8

[0084] A method for eliminating carbon enrichment in the transition zone of a dissimilar metal argon arc welding joint includes the following steps:

[0085] Beveling of base material: Beveling is performed on the base material 321 austenitic stainless steel plate (material size 250mm×150mm×12mm) and 617 nickel-based alloy plate (material size 250mm×150mm×12mm) to form a single-sided V-shaped bevel with a bevel angle of 27.5°. Acetone and alcohol are used to remove oil stains from the bevel surface.

[0086] 617 nickel-based alloy isolation layer: The manual argon arc welding method is adopted. The welding process parameters of manual argon arc welding are: current 120A, voltage 10V-11V, welding speed 2.0mm / s, shielding gas argon purity 99.999%, gas flow rate 15L / min. 617 nickel-based alloy welding wire (diameter 2.4mm) of grade ERNiCrCoMo-1 is welded onto the surface of 321 austenitic stainless steel plate with a bevel to form a 617 nickel-based alloy isolation layer.

[0087] Second beveling, assembly and spot welding: After the 617 nickel-based alloy isolation layer is overlaid, the 321 austenitic stainless steel plate is beveled again to form a single-sided V-shaped bevel with a bevel angle of 27.5°. The thickness of the 617 nickel-based alloy isolation layer is controlled to be ≥3mm. The bevel surface is cleaned with acetone and alcohol to remove oil stains. Then it is assembled with the 617 nickel-based alloy plate and spot welded at both ends for fixation.

[0088] Assembled welding: The 321 austenitic stainless steel plate and 617 nickel-based alloy plate were assembled and tack-welded using tungsten inert gas (TIG) welding. The TIG welding process parameters were: current 122A, voltage 12.3V, welding speed 125mm / min, shielding gas argon purity 99.999%, and gas flow rate 15L / min.

[0089] After welding, the cross-section of the weld joint was cut using an electric discharge wire cutter. After electrolytic etching with aqua regia and oxalic acid, a metallographic sample of the weld joint cross-section was prepared. The microstructure and carbon element distribution were characterized using a field emission electron probe microanalyzer (model JXA-iHP200F). Four locations were randomly tested, such as... Figure 8 The microstructure shown in (a) indicates that a transition zone (the area indicated by the dashed line in the figure) still exists in the dissimilar metal welded joint, but no carbon enrichment is observed in the transition zone. Figure 8 (b) The carbon element distribution diagram is shown.

[0090] Comparative Example 1

[0091] Both the 321 austenitic stainless steel plate (250mm×150mm×12mm) and the 617 nickel-based alloy plate (250mm×150mm×12mm) were beveled to form a single-sided V-shaped bevel with a bevel angle of 27.5°. The bevel surfaces were cleaned with acetone and alcohol to remove oil. The two plates were then assembled and spot-welded at both ends. The assembly was performed using manual argon arc welding with ERNiCrCoMo welding wire. 1 (diameter 2.4mm), the assembly welding process parameters are: current: 120A, voltage 12V-12.5V, welding speed 120mm / min, shielding gas is 99.999% pure argon, gas flow rate 10L / min; after welding, the cross-section of the welded joint was cut using an electric spark wire cutter, and after electrolytic etching with aqua regia and oxalic acid, the microstructure and carbon element distribution in the transition zone and its vicinity were observed and analyzed using a field emission electron probe microanalysis system (model JXA-iHP200F). Four locations were randomly tested, such as... Figure 9 (a) shows the microstructure and Figure 9 (b) shows the carbon element distribution, and it can be seen that there is obvious carbon enrichment in the transition zone of the dashed line area.

Claims

1. A method for eliminating carbon enrichment in the transition zone of a dissimilar metal argon arc welding joint, characterized in that, Includes the following steps: Beveling of base material: Beveling is performed on the base material 321 austenitic stainless steel plate and 617 nickel-based alloy plate respectively, and the bevel surface is cleaned to remove oil stains; 617 nickel-based alloy isolation layer: By adjusting the welding process parameters of manual argon arc welding, 617 nickel-based alloy welding wire is deposited on the surface of 321 austenitic stainless steel plate with a pre-grooved groove to form a 617 nickel-based alloy isolation layer. Second beveling, assembly and spot welding: After the 617 nickel-based alloy isolation layer is overlaid, the 321 austenitic stainless steel plate is beveling again, the thickness of the 617 nickel-based alloy isolation layer is controlled, the bevel surface is cleaned to remove oil stains, and then it is assembled with the 617 nickel-based alloy plate and spot welded at both ends for fixation. Assembled welding: The 321 austenitic stainless steel plate and 617 nickel-based alloy plate are assembled and tack-welded using tungsten inert gas (TIG) welding. The TIG welding process parameters are adjusted to complete the welding.

2. The method for eliminating carbon enrichment in the transition zone of dissimilar metal argon arc welding joints as described in claim 1, characterized in that, In the beveling process of the base material, 321 austenitic stainless steel plate and 617 nickel-based alloy plate are processed into a single-sided V-shaped bevel with a bevel angle of 27.5°. The bevel surface is cleaned with acetone and alcohol.

3. The method for eliminating carbon enrichment in the transition zone of dissimilar metal argon arc welding joints as described in claim 1, characterized in that, In the surfacing of the 617 nickel-based alloy isolation layer, the 617 nickel-based alloy welding wire is grade ERNiCrCoMo-1 with a diameter of 0.8mm-2.4mm.

4. The method for eliminating carbon enrichment in the transition zone of dissimilar metal argon arc welding joints as described in claim 1, characterized in that, The welding process parameters for manual argon arc welding in the surfacing of 617 nickel-based alloy isolation layer are: current 80A-120A, voltage 8V-12V, welding speed 1.5mm / s-2.0mm / s, shielding gas argon purity ≥99.999%, and gas flow rate 10L / min-20L / min.

5. The method for eliminating carbon enrichment in the transition zone of dissimilar metal argon arc welding joints as described in claim 1, characterized in that, During the re-beveling, assembly, and spot welding, the 321 austenitic stainless steel plate was re-processed into a single-sided V-shaped bevel with a bevel angle of 27.5°. After re-beveling, the thickness of the 617 nickel-based alloy isolation layer was controlled to be ≥3mm. The bevel surface was cleaned with acetone and alcohol.

6. The method for eliminating carbon enrichment in the transition zone of dissimilar metal argon arc welding joints as described in claim 1, characterized in that, In the assembly welding, the process parameters for tungsten inert gas (TIG) argon arc welding are: current 120A-125A, voltage 12V-13V, welding speed 120mm / min-125mm / min, shielding gas argon purity ≥99.999%, and gas flow rate 10L / min-20L / min.

7. The application of the method for eliminating carbon enrichment in the transition zone of a dissimilar metal argon arc welded joint as described in claim 1, characterized in that, Dissimilar metal welding of 617 nickel-based alloy and 321 austenitic stainless steel for use in nuclear power and chemical industries.

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