A welding method for optimizing the weld microstructure of nickel-based alloy composite plates

Abstract

This invention discloses a welding method for optimizing the weld microstructure of a nickel-based alloy composite plate. The nickel-based alloy composite plate includes a base material layer and a nickel-based alloy composite layer, with a transition layer at the interface between the base material layer and the nickel-based alloy composite layer. The welding method includes the following steps: machining a trapezoidal bevel on the welding section of the nickel-based alloy composite plate corresponding to the position of the base material layer; machining a U-shaped bevel on the welding section of the nickel-based alloy composite plate corresponding to the position of the transition layer; not machining a bevel on the welding section of the nickel-based alloy composite plate corresponding to the position of the nickel-based alloy composite layer, retaining a blunt edge; welding the nickel-based alloy composite layer using single tungsten inert gas (TIG) welding; welding the transition layer using single TIG welding; and welding the base material layer using single TIG welding.

Description

Technical Field

[0001] This invention relates to a welding method, and more particularly to a welding method for composite plates. Background Technology

[0002] Nickel-based alloy composite plates are a type of metal composite structural material that combines corrosion resistance with good mechanical properties. Because its base material has two component metals, the connection process requires multi-layer, multi-pass welding, which divides the composite plate weld into three layers: the nickel-based alloy weld of the composite layer, the transition layer weld, and the carbon steel weld of the base layer.

[0003] In the manufacturing of some composite plate components, due to limited operating space, a welding sequence of composite layer-transition layer-substrate layer must be adopted. Since the content of Cr and Ni alloying elements in nickel-based alloys is very high, if conventional welding processes are used under this welding sequence, the carbon steel weld bead adjacent to the transition layer can easily melt into excessive alloying elements, resulting in martensitic structure, which in turn causes hardening and embrittlement, significantly reducing the mechanical properties of the joint.

[0004] Currently, the existing technology addresses this problem in the welding process of bimetallic composite plates by using corrosion-resistant alloy welding materials for the entire weld seam. For example, the national standard "Technical Requirements for Welding of Stainless Steel Composite Plates" (GB / T 13148—2008) specifies the welding of composite plates under this welding sequence. In this case, the welding of the base layer weld seam should preferably use corrosion-resistant alloy welding wire with performance matching that of the composite layer.

[0005] However, this method has several drawbacks when used on nickel-based alloy composite plates. First, the material cost of nickel-based alloys is often several times that of stainless steel. Significantly increasing the amount of nickel-based alloy filler metal will reduce welding efficiency and significantly increase welding costs. Second, the yield strength of nickel-based alloys is lower than that of carbon steel. If nickel-based alloy welding material is used to fill the entire weld, the yield strength of the joint will also decrease, increasing the risk of failure of the nickel-based alloy composite plate joint under heavy loads.

[0006] In addition, Chinese patent document CN112122783A, published on December 25, 2020, entitled "A Laser Butt Welding Method for Carbon Steel-Nickel Alloy Composite Plate", proposes to achieve the connection of composite layers by using laser self-fusion or filler wire welding under the condition of limited construction space and the requirement to weld the composite layer first. However, it focuses on the problem that the composite plate cannot be welded on one side under this welding sequence, without paying attention to the performance changes of the mixed weld bead of nickel-based alloy and carbon steel.

[0007] In addition, Chinese patent document CN113042895B, published on April 26, 2022, entitled "A Welding Method for a Nickel-Steel Composite Structure", proposes to complete the connection of the composite layer by laser self-fusion welding when the composite layer is welded first, and then to weld the adjacent weld bead by cold metal transfer welding, thereby completing the connection of the nickel-based alloy composite plate under this welding sequence. However, it mainly addresses the problem of reduced corrosion resistance of the composite layer caused by element migration at the interface between the composite layer and the substrate layer, and does not solve the problem of reduced toughness of the mixed weld bead of nickel-based alloy and carbon steel.

[0008] In addition, the above methods all use laser autofusion or filler wire welding when welding composite plates. These welding methods have very high requirements for the assembly accuracy of components, and the equipment is expensive, the operation is cumbersome, and the maintenance is difficult. Summary of the Invention

[0009] The purpose of this invention is to provide a welding method for optimizing the weld microstructure of nickel-based alloy composite plates. This method is based on the welding sequence of composite layer-transition layer-substrate layer and adopts the common tungsten inert gas welding method. Through bevel design, the excessive melting of alloying elements of nickel-based alloys by the first weld layer of the substrate layer can be effectively reduced, thereby effectively controlling the dilution rate of the weld layer, improving the microstructure, and achieving a reliable connection of the composite plate.

[0010] To achieve the above objectives, the present invention provides a welding method for optimizing the weld microstructure of a nickel-based alloy composite plate. The nickel-based alloy composite plate comprises a substrate layer and a nickel-based alloy composite layer, wherein a transition layer is provided at the interface between the substrate layer and the nickel-based alloy composite layer. The welding method includes the following steps:

[0011] A trapezoidal bevel is machined on the welding section of the nickel-based alloy composite plate at the position corresponding to the base material layer; a U-shaped bevel is machined on the welding section of the nickel-based alloy at the position corresponding to the transition layer; no bevel is machined on the welding section of the nickel-based alloy composite plate at the position corresponding to the nickel-based alloy composite layer, and the blunt edge is retained.

[0012] The nickel-based alloy composite layer was welded using single tungsten inert gas welding.

[0013] The transition layer was welded using single tungsten inert gas welding;

[0014] The substrate layer was welded using single tungsten inert gas welding.

[0015] Furthermore, in the welding method for optimizing the weld structure of nickel-based alloy composite plates described in this invention, the angle α between the inclined portion of the trapezoidal bevel and the vertical direction is 15-25°.

[0016] In this implementation, in order to balance the operability of the argon arc welding torch and the filling efficiency, the angle α between the inclined part of the trapezoidal bevel and the vertical direction can be controlled between 15-25°.

[0017] Furthermore, in the welding method for optimizing the weld structure of nickel-based alloy composite plates described in this invention, the single-side width w1 of the trapezoidal groove step is ≥ 2(w2+2r) / 3, where w2 represents the assembly gap and r represents the radius of the transition arc of the U-shaped groove, and the unit parameter is mm.

[0018] In this implementation, by controlling the single-side width w1 of the trapezoidal bevel step to be greater than 2(w2+2r) / 3, the ratio of the width of the first weld bead and the transition layer in direct contact with the subsequent substrate layer to its weld width is less than 35%, which will help control the low dilution rate of each weld bead in this layer.

[0019] Furthermore, in the welding method for optimizing the weld structure of nickel-based alloy composite plates described in this invention, the distance b4 between the step of the trapezoidal groove and the interface between the substrate layer and the nickel-based alloy composite layer is 0.5-1.5 mm.

[0020] In this implementation, steps can be machined within the weld seam of the substrate layer to facilitate the forming control of the first weld bead of the substrate layer. To ensure that this weld bead is in direct contact with the base material of the composite layer during welding, the distance b4 between the step of the trapezoidal bevel and the interface between the substrate layer and the nickel-based alloy composite layer can be controlled to be between 0.5 and 1.5 mm.

[0021] Furthermore, in the welding method for optimizing the weld structure of nickel-based alloy composite plates described in this invention, the thickness b3 of the blunt edge is 0.5-2 mm.

[0022] In this implementation, to facilitate single-sided welding and double-sided forming of the nickel-based alloy weld seam in the composite layer, a bevel can be left unprocessed on the welding section of the nickel-based alloy composite plate corresponding to the position of the nickel-based alloy composite layer; instead, a blunt edge can be retained. The thickness of the blunt edge, b3, can be controlled within the range of 0.5-2 mm.

[0023] Furthermore, in the welding method for optimizing the weld structure of nickel-based alloy composite plates described in this invention, the assembly gap w2 is 1-3 mm.

[0024] In this implementation, by controlling the assembly gap w2 between 1-3mm, welding can be facilitated.

[0025] Furthermore, in the welding method for optimizing the weld structure of nickel-based alloy composite plates described in this invention, the radius r of the transition arc of the U-shaped groove is (b2-b3) / 2, where b2 represents the distance from the surface of the nickel-based alloy composite layer to its interface with the substrate layer, and b3 is the thickness of the blunt edge, with each parameter in mm.

[0026] In this implementation, due to the poor fluidity of the nickel-based alloy molten pool, in order to ensure good forming and avoid the generation of unfused defects at the bottom of the molten pool, the bottom position of the transition layer weld can be processed into a U-shaped bevel, and the radius of the transition arc of the U-shaped bevel is controlled as r = (b2-b3) / 2.

[0027] Furthermore, in the welding method for optimizing the weld structure of nickel-based alloy composite plates described in this invention, in the step of welding the nickel-based alloy composite layer using single tungsten inert gas welding: pure argon gas (purity not less than 99%) is used as the shielding gas, a nickel-based alloy solid welding wire matching the nickel-based alloy composite layer is used, the welding voltage is controlled at 10-13V, the welding current at 80-110A, the welding speed at 80-110mm / min, and the wire feed speed at 0.3-0.8m / min.

[0028] In this implementation, the above process can ensure that the weld beads on the surface of the composite layer have sufficiently good weld formation under the premise of single-sided operation on the substrate layer side.

[0029] Furthermore, in the welding method for optimizing the weld structure of nickel-based alloy composite plates described in this invention, in the step of welding the transition layer using single tungsten inert gas welding: pure argon gas (purity not less than 99%) is used as the shielding gas, a nickel-based alloy solid welding wire matching the nickel-based alloy composite layer is used, the welding voltage is controlled at 9-13V, the welding current at 80-130A, the welding speed at 100-120mm / min, and the wire feed speed at 0.6-1.0m / min.

[0030] In this implementation, the above process can ensure good fusion between the transition layer weld and the composite layer weld and the base material, while the surface has good weld formation. The flat surface to be welded will be beneficial to the forming control of the subsequent carbon steel weld of the base layer, especially the first weld bead of the base layer.

[0031] Furthermore, in the welding method for optimizing the weld structure of nickel-based alloy composite plates described in this invention, in the step of welding the substrate layer using single tungsten inert gas welding:

[0032] First, the first weld bead of the substrate layer that is in direct contact with the transition layer is welded: the shielding gas is a mixture of argon and CO2, and the flux-cored welding wire is matched with the substrate layer.

[0033] Complete the welding of other weld passes in the base layer: use pure argon gas (purity not less than 99%) as the shielding gas, and use solid carbon steel welding wire that matches the base layer.

[0034] Furthermore, in the welding method for optimizing the weld structure of nickel-based alloy composite plates described in this invention, when welding the first layer of the substrate layer, it is divided into three passes. The welding sequence is to weld the two side passes first, followed by the middle pass. When welding the two side passes, the distance in the width direction between the center of the welding torch and the edge of the trapezoidal bevel step is controlled as (w1+2((w2+2r) / 3) / 2, where w1 represents the single-side width of the trapezoidal bevel step, w2 represents the assembly gap, and r represents the radius of the transition arc of the U-shaped bevel. All parameters are in mm. In this embodiment, the overlap rate between each weld and the transition layer weld can be controlled to 33%.

[0035] Furthermore, in the welding method for optimizing the weld structure of nickel-based alloy composite plates described in this invention, when welding the first weld bead of the substrate layer: the welding voltage is controlled at 14-16V, the welding current at 150-180A, the welding speed at 120-150mm / min, and the wire feeding speed at 2.7-3.0m / min.

[0036] In this implementation, the transition layer weld obtained by combining the bevel design and the aforementioned weld optimization process can ensure that the dilution level of the carbon steel weld layer relative to the composite layer weld is less than 3.0%, thereby preventing the microstructure of the weld layer from being transformed into martensite as a whole and maintaining good plasticity and toughness.

[0037] Furthermore, in the welding method for optimizing the weld structure of nickel-based alloy composite plates described in this invention, when welding other weld passes of the substrate layer: the welding voltage is controlled at 14-16V, the welding current at 250-280A, the welding speed at 150-180mm / min, and the wire feeding speed at 2.6-3.0m / min.

[0038] The welding method for optimizing the weld microstructure of nickel-based alloy composite plates described in this invention has the following advantages and beneficial effects compared to the prior art:

[0039] The welding method described in this invention can effectively control the dilution rate of the first layer of carbon steel weld that is in direct contact with the transition layer weld, avoid the overall hardening and embrittlement transformation of the microstructure, and achieve a reliable connection of the composite plate joint.

[0040] Furthermore, compared to existing technologies that require the use of all-nickel-based alloy welding materials in this welding scenario, the welding method described in this invention improves the structural strength of the joint, significantly reduces welding costs, increases welding efficiency, and enhances economic benefits.

[0041] In addition, the welding method described in this invention requires simple equipment, has low assembly accuracy requirements, and is easy to operate, making it highly scalable for engineering sites. Attached Figure Description

[0042] Figure 1 The diagram schematically illustrates the bevel used in the welding method for optimizing the weld structure of nickel-based alloy composite plates according to the present invention.

[0043] Figure 2 The image shows a microstructure of the first weld interface between the transition layer and the carbon steel substrate layer in the welded joint of the optimized nickel-based alloy composite plate weld structure according to Example 1 of the present invention. Detailed Implementation

[0044] The welding method for optimizing the weld structure of nickel-based alloy composite plates according to the present invention will be further explained and described below with reference to specific embodiments and accompanying drawings. However, this explanation and description do not constitute an undue limitation on the technical solution of the present invention.

[0045] Figure 1 The image shows two spliced ​​nickel-based alloy composite plates, A and B. Figure 1 The dashed line O in the figure represents the splicing seam. The nickel-based alloy composite plate includes a carbon steel substrate layer 1 and a nickel-based alloy composite layer 2, with a transition layer at the interface between the carbon steel substrate layer 1 and the nickel-based alloy composite layer 2. Figure 1 The designation “b1” indicates the distance between the surface of the carbon steel substrate layer and the interface between it and the nickel-based alloy composite layer, and the designation “b2” indicates the distance between the surface of the nickel-based alloy composite layer and the interface between it and the carbon steel substrate layer.

[0046] In one specific embodiment, a nickel-based alloy composite plate with the grade Incoloy 825 / X52 can be used, i.e., the substrate layer material is X52 and the nickel-based alloy composite layer material is Incoloy 825. The thickness of the nickel-based alloy composite plate is 13mm, wherein b1 of the nickel-based alloy composite plate is 10mm and b2 is 3mm.

[0047] In some embodiments, the optimized welding method for nickel-based alloy composite plates may include the steps of:

[0048] 100: Processing at the welding position of the two spliced ​​nickel-based alloy composite plates A and B as follows Figure 1 The bevel is shown. Specifically, a trapezoidal bevel is machined on the welding section of the nickel-based alloy composite plate at the position corresponding to the carbon steel substrate layer. This trapezoidal bevel includes a sequentially arranged inclined portion 7 and a step 8 of the trapezoidal bevel, wherein the width of one side of the step 8 of the trapezoidal bevel is represented by w1. In some more specific embodiments, the width of one side of the step 8 of the trapezoidal bevel, w1, is ≥ 2(w2 + 2r) / 3.

[0049] By controlling the single-sided width w1 of the trapezoidal bevel step, it can be ensured that the ratio of the width of the first weld bead and the transition layer in direct contact with the subsequent substrate layer to its weld width is less than 35%, which will help control the low dilution rate of each weld bead in this layer.

[0050] The distance between the plane of step 8 of the trapezoidal bevel and the interface between the substrate layer and the nickel-based alloy composite layer is... Figure 1 The designation is "b4". In some more specific embodiments, the distance b4 between the step 8 plane of the trapezoidal bevel and the interface between the substrate layer and the nickel-based alloy composite layer can be controlled between 0.5 and 1.5 mm.

[0051] By controlling the distance between the step 8 plane of the trapezoidal bevel and the interface between the substrate layer and the nickel-based alloy composite layer, the formation of the first weld bead of the substrate layer can be coordinated and the weld bead of this layer can be ensured to be in direct contact with the base material of the composite layer during welding.

[0052] In some more specific implementations, the angle α between the inclined portion of the trapezoidal bevel and the vertical direction can be controlled between 15-25°, which helps to balance the operability of the argon arc welding torch and the filling efficiency.

[0053] A U-shaped bevel is made on the welding section of the nickel-based alloy composite plate at the positions corresponding to the transition layer and the nickel-based alloy composite layer. This U-shaped bevel has a transition arc 9, where r represents the radius of the transition arc of the U-shaped bevel. In some more specific embodiments, due to the poor fluidity of the molten pool of the nickel-based alloy, in order to ensure good forming and avoid the generation of unfused defects at the bottom of the molten pool, the radius of the transition arc of the U-shaped bevel can be controlled as r = (b2-b3) / 2.

[0054] On the welding section of the nickel-based alloy composite plate, at the position corresponding to the nickel-based alloy composite layer, no beveling is performed; a blunt edge of 10 is retained, and the thickness of the blunt edge is... Figure 1 The designation is "b3". In some more specific embodiments, the blunt edge thickness b3 can be controlled within the range of 0.5-2mm, which facilitates single-sided welding and double-sided forming of the nickel-based alloy weld in the composite layer.

[0055] Assembly gap at Figure 1 The gap is indicated by "w2". In some more specific implementations, the assembly gap w2 can be 1-3mm to facilitate welding.

[0056] 200: The nickel-based alloy composite layer 2 is welded using single tungsten inert gas (TIG) welding to obtain the composite layer weld 3. The shielding gas used for welding is pure argon gas with a purity of not less than 99%. The welding uses nickel-based alloy solid welding wire that matches the nickel-based alloy composite layer. The welding process parameters can be controlled as follows: the welding voltage is controlled at 10-13V, the welding current is controlled at 80-110A, the welding speed is controlled at 80-110mm / min, and the wire feed speed is controlled at 0.3-0.8m / min.

[0057] By using the above welding process, it is possible to ensure that the weld beads on the surface of the composite layer have sufficiently good weld formation under the premise of single-sided operation on the substrate layer side.

[0058] 300: The transition layer is welded using single tungsten inert gas welding to obtain transition layer weld 4. The shielding gas used during welding is pure argon gas with a purity of not less than 99%, and the welding material is nickel-based alloy solid welding wire that matches the nickel-based alloy composite layer. The welding process parameters can be controlled as follows: welding voltage is 9-13V, welding current is 80-130A, welding speed is 100-120mm / min, and wire feed speed is 0.6-1.0m / min.

[0059] By adopting the above welding process, it is possible to ensure good fusion between the transition layer weld and the composite layer weld and the base material, while the surface has good weld formation. The flat surface to be welded will be beneficial to the formation control of the subsequent carbon steel weld of the base layer, especially the first weld bead of the base layer.

[0060] 400: The substrate layer is welded using single tungsten inert gas welding, wherein:

[0061] First, weld bead 5, which contacts the transition layer, is welded. This layer is welded in three passes, with the two side passes welded first, followed by the middle pass. The shielding gas is an argon + CO2 mixture, such as 78% Ar + 18% CO2, and the welding material is a flux-cored wire that matches the carbon steel base layer.

[0062] Then, complete the welding of the other weld passes 6 of the base layer: the shielding gas is pure argon gas with a purity of not less than 99%, and the welding wire is solid carbon steel welding wire that matches the carbon steel base layer.

[0063] In some more specific embodiments, when welding the first weld bead 5, the welding voltage can be controlled to be 14-16V, the welding current to be 150-180A, the welding speed to be 120-150mm / min, and the wire feed speed to be 2.7-3.0m / min.

[0064] Furthermore, in some more specific embodiments, when welding the first weld bead 5: the distance between the center of the welding torch and the edge of the trapezoidal bevel step can be controlled as (w1+2((w2+2r) / 3) / 2. Using this embodiment, the overlap rate between each weld bead and the transition layer weld bead can be controlled to 33%.

[0065] In this embodiment, the transition layer weld obtained by combining the bevel design and the aforementioned weld optimization process can ensure that the dilution level of the carbon steel weld layer relative to the composite layer weld is less than 3.0%, thereby preventing the microstructure of the weld layer from being transformed into martensite as a whole and maintaining good plasticity and toughness.

[0066] In some more specific embodiments, when welding other weld passes 6 of the carbon steel substrate layer, the welding voltage can be controlled to be 14-16V, the welding current to be 250-280A, the welding speed to be 150-180mm / min, and the wire feed speed to be 2.6-3.0m / min.

[0067] To further demonstrate the technical effects of the preferred embodiments of this invention, Table 1 lists the characteristic parameters of the bevel used in the preferred embodiments 1-5 of this invention.

[0068] Table 1.

[0069]

[0070] Table 2 lists the welding process parameters used in the step of forming the nickel-based alloy composite layer weld in the preferred embodiments 1-5 of the present invention.

[0071] Table 2.

[0072]

[0073] Table 3 lists the welding process parameters used in the step of forming the transition layer weld in the preferred embodiments 1-5 of the present invention.

[0074] Table 3.

[0075]

[0076] Table 4 lists the welding process parameters used in the step of forming the first weld bead of the carbon steel substrate layer in the preferred embodiments 1-5 of the present invention.

[0077] Table 4.

[0078]

[0079] Table 5 lists the welding process parameters used in the steps of forming other weld passes in the carbon steel substrate layer in the preferred embodiments 1-5 of the present invention.

[0080] Table 5.

[0081]

[0082] Furthermore, to demonstrate the effectiveness of the preferred embodiment, Table 6 lists the Cr content of each base material layer and weld in the welded joint of the nickel-based alloy composite plate obtained by welding according to Embodiment 1 of the present invention. Calculations show that the dilution rate of the first carbon steel weld bead 5, which is in direct contact with the transition layer, is 1.81%. Therefore, the formation of martensitic structure in the carbon steel base material layer weld can be avoided.

[0083] Table 6.

[0084]

[0085] Figure 2 The image shows a microstructure of the first weld interface between the transition layer and the carbon steel substrate layer in the welded joint of the optimized nickel-based alloy composite plate weld structure according to Example 1 of the present invention.

[0086] from Figure 2 The images show the microstructure of the transition layer / substrate layer carbon steel first layer weld interface after corrosion with nitric acid alcohol solution in the optimized welded joint of the nickel-based alloy composite plate prepared by the method of this invention. It can be seen that the transition layer weld was not corroded, indicating that the weld microstructure of this layer remains a fully austenitic corrosion-resistant microstructure of the parent phase. Meanwhile, the adjacent carbon steel weld retains a ferrite grain structure, indicating that the weld layer did not undergo overall martensitic hardening and embrittlement. This confirms that the weld microstructure has been effectively optimized.

[0087] It should be noted that the combination of the technical features in this case is not limited to the combination methods described in the claims of this case or the combination methods described in the specific embodiments. All technical features described in this case can be freely combined or combined in any way, unless they contradict each other.

[0088] It should also be noted that the embodiments listed above are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and similar changes or modifications made thereto are those that can be directly derived or easily conceived by those skilled in the art from the content disclosed in the present invention, and should all fall within the protection scope of the present invention.

Claims

1. A welding method for optimizing the weld microstructure of a nickel-based alloy composite plate, wherein the nickel-based alloy composite plate comprises a substrate layer and a nickel-based alloy composite layer, and a transition layer is provided at the interface between the substrate layer and the nickel-based alloy composite layer; characterized in that, The welding method includes the following steps: A trapezoidal bevel is machined on the welding section of the nickel-based alloy composite plate at the position corresponding to the base material layer; a U-shaped bevel is machined on the welding section of the nickel-based alloy at the position corresponding to the transition layer; no bevel is machined on the welding section of the nickel-based alloy composite plate at the position corresponding to the nickel-based alloy composite layer, and the blunt edge is retained. The nickel-based alloy composite layer was welded using single tungsten inert gas welding. The transition layer was welded using single tungsten inert gas welding; The substrate layer was welded using single tungsten inert gas welding.

2. The welding method as described in claim 1, characterized in that, The angle α between the inclined part of the trapezoidal bevel and the vertical direction is 15-25°.

3. The welding method as described in claim 1, characterized in that, The single-side width w1 of the trapezoidal bevel step is greater than or equal to 2(w2+2r) / 3, where w2 represents the assembly gap and r represents the radius of the transition arc of the U-shaped bevel. The unit parameters are all mm.

4. The welding method as described in claim 1, characterized in that, The distance b4 between the step of the trapezoidal bevel and the interface between the substrate layer and the nickel-based alloy composite layer is 0.5-1.5 mm.

5. The welding method as described in claim 1, characterized in that, The thickness b3 of the blunt edge is 0.5-2 mm.

6. The welding method as described in claim 1, characterized in that, The assembly clearance w2 is 1-3mm.

7. The welding method as described in claim 1, characterized in that, The radius of the transition arc of the U-shaped bevel is r = (b2-b3) / 2, where b2 represents the distance from the surface of the nickel-based alloy composite layer to its interface with the substrate layer, and b3 is the thickness of the blunt edge. The unit parameter is mm.

8. The welding method as described in claim 1, characterized in that, In the steps of welding nickel-based alloy composite layers using single tungsten inert gas welding: pure argon is used as the shielding gas, a nickel-based alloy solid welding wire that matches the nickel-based alloy composite layer is used, the welding voltage is controlled at 10-13V, the welding current is 80-110A, the welding speed is 80-110mm / min, and the wire feed speed is 0.3-0.8m / min.

9. The welding method as described in claim 1, characterized in that, In the step of welding the transition layer using single tungsten inert gas welding: pure argon is used as the shielding gas, and a nickel-based alloy solid welding wire that matches the nickel-based alloy composite layer is used. The welding voltage is controlled at 9-13V, the welding current at 80-130A, the welding speed at 100-120mm / min, and the wire feed speed at 0.6-1.0m / min.

10. The welding method as described in claim 1, characterized in that, In the step of welding the substrate layer using tungsten inert gas welding: First, the first weld bead of the substrate layer that is in direct contact with the transition layer is welded: the shielding gas is a mixture of argon and CO2, and the flux-cored welding wire is matched with the substrate layer. Complete the welding of other weld passes in the base layer: use pure argon as the shielding gas and solid carbon steel welding wire that matches the base layer.

11. The welding method as described in claim 10, characterized in that, When welding the first layer of the substrate layer, it is divided into three passes. The welding sequence is to weld the two side passes first, and then weld the middle pass. When welding the two side passes, the distance between the center of the welding gun and the edge of the trapezoidal bevel step in the width direction is controlled as (w1+2((w2+2r) / 3) / 2, where w1 represents the single-side width of the trapezoidal bevel step, w2 represents the assembly gap, and r represents the radius of the transition arc of the U-shaped bevel. All parameters are in mm.

12. The welding method as described in claim 10, characterized in that, When welding the first weld bead of the substrate layer: control the welding voltage to be 14-16V, the welding current to be 150-180A, the welding speed to be 120-150mm / min, and the wire feed speed to be 2.7-3.0m / min.

13. The welding method as described in claim 10, characterized in that, When welding other weld passes of the substrate layer: control the welding voltage to be 14-16V, the welding current to be 250-280A, the welding speed to be 150-180mm / min, and the wire feed speed to be 2.6-3.0m / min.

Images