A welding method for nickel-based alloy composite plates

Abstract

This invention discloses a welding method for a nickel-based alloy composite plate, the nickel-based alloy composite plate comprising 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: machining a composite bevel on the welding cross-section of the nickel-based alloy composite plate at a position corresponding to the substrate layer, the composite bevel comprising a vertically inclined portion, a horizontal portion, and a transition arc provided between the vertically inclined portion and the horizontal portion; opening a rectangular bevel on the welding cross-section of the nickel-based alloy at a position corresponding to the transition layer; not machining a bevel on the welding cross-section of the nickel-based alloy composite plate at a position corresponding to the nickel-based alloy composite layer; performing self-fusion welding of the nickel-based alloy composite layer using laser welding; using carbon steel welding wire matched with the substrate layer, performing filler wire welding of the transition layer using laser welding; and welding the substrate layer using hot-wire pulsed tungsten inert gas 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] Because it contains a large number of precious metal elements, the unit price of nickel-based alloys is dozens of times that of low-alloy carbon steel. Therefore, in engineering construction that requires the use of nickel-based alloys (with high corrosion resistance requirements), material cost is a very important consideration. In this case, using nickel-based alloy composite plates can meet the construction requirements to a certain extent.

[0003] However, because the base material of nickel-based alloy composite plates contains two different metals—nickel-based alloy and carbon steel—different welding materials are required for welding the cladding layer and the base material layer separately, with a transition layer added between them; this is known as multi-layer, multi-pass welding. The base material layer is typically welded using carbon steel welding wire, which is less expensive, while the transition layer and cladding layer use nickel-based alloy welding materials, which are dozens of times more expensive than carbon steel welding materials. Thus, as the weld length increases, the amount of nickel-based alloy welding materials used also increases significantly, representing a substantial construction cost for large-scale projects.

[0004] Chinese patent document CN113042895A, published on June 29, 2021, entitled "A Welding Method for a Nickel-Steel Composite Structure," discloses that: when the composite layer is welded first, laser self-fusion welding is used to complete the connection of the composite layer. Then, carbon steel welding wire is used in conjunction with arc welding to complete the connection of the nickel-based alloy composite plate in this welding sequence. The entire connection process can also be completed without the use of carbon steel welding wire. 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. It does not take measures to control the problem of martensitization of the microstructure of the carbon steel weld. Summary of the Invention

[0005] One of the objectives of this invention is to provide a welding method for nickel-based alloy composite plates. This method can reliably connect nickel-based alloy composite plates throughout the entire process using only carbon steel welding materials. In particular, it can use carbon steel welding materials to weld a transition layer weld, completing the compositional transition from the nickel-based alloy to the substrate layer. Thus, reliable connection of nickel-based alloy composite plates can be achieved without the use of nickel-based alloy welding materials, reducing the welding cost of nickel-based alloy composite plates and generating considerable economic benefits.

[0006] To achieve the above objectives, the present invention provides a welding method for 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; wherein the welding method includes the following steps:

[0007] A composite bevel is machined on the welding section of the nickel-based alloy composite plate at the position corresponding to the base material layer. The composite bevel includes a vertically inclined portion, a horizontal portion, and a transition arc between the vertically inclined portion and the horizontal portion. A rectangular bevel is opened 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.

[0008] Laser welding was used to perform self-fusion welding on nickel-based alloy composite layers;

[0009] Using carbon steel welding wire that matches the base layer, laser welding is used to filler wire welding the transition layer;

[0010] The substrate layer was welded using hot-wire pulsed tungsten inert gas welding.

[0011] The welding method described in this invention avoids the overall martensite formation of carbon steel welds caused by excessive melting of weld alloy elements in the transition layer. This allows for the use of carbon steel welding materials to fill the transition layer weld, achieving a smooth transition of the microstructure from nickel-based alloy to carbon steel and enabling reliable connection of nickel-based alloy composite plates. Applying this invention to the welding process of nickel-based alloy composite plate components in engineering can significantly reduce the amount of nickel-based alloy welding materials used, resulting in considerable economic benefits.

[0012] Furthermore, in the welding method for nickel-based alloy composite plates described in this invention, the single-side width w1 / 2 of the rectangular groove is greater than or equal to the laser spot radius of the laser weld.

[0013] In this implementation, rectangular bevels are opened on both sides at the transition layer weld position. When the two nickel-based alloy composite plates are welded together, the sum of the widths of the two rectangular bevels, w1, is greater than the diameter of the laser spot. This ensures that the laser self-fusion welding of the composite layer weld is completed smoothly without melting the carbon steel substrate.

[0014] Furthermore, in the welding method for nickel-based alloy composite plates described in this invention, the thickness b3 of the rectangular groove satisfies 0.2mm≤b3≤0.5b2, where b2 represents the distance from the surface of the nickel-based alloy composite layer to its interface with the substrate layer, and its unit parameter is mm.

[0015] In this implementation, the thickness b3 of the rectangular groove, i.e., the distance between the weld step of the base layer and the interface between the base layer and the nickel-based alloy composite layer, can be controlled within a certain range and should be as small as possible. However, if b3 is too small, the base layer weld, especially several weld passes in the first layer, will require very shallow penetration to avoid melting through the base layer to the nickel-based alloy composite layer. Therefore, the range of b3 can be limited to 0.2mm ≤ b3 ≤ 0.5b2mm.

[0016] Furthermore, in the welding method for nickel-based alloy composite plates described in this invention, the angle α between the vertically inclined portion and the vertical direction is ≥ (1.5b1)°, where b1 represents the distance from the surface of the substrate layer to its interface with the nickel-based alloy composite layer, and its unit parameter is mm.

[0017] Furthermore, in the welding method for nickel-based alloy composite plates described in this invention, the extension length w2 of the horizontal portion is ≥ (5 + 0.1b1), where b1 represents the distance from the surface of the substrate layer to its interface with the nickel-based alloy composite layer, and its unit parameter is mm.

[0018] In this implementation, to facilitate subsequent hot-wire pulse tungsten inert gas welding operations, the extension length w2 of the horizontal section is controlled to be greater than or equal to (5 + 0.1b1).

[0019] Furthermore, in the welding method for nickel-based alloy composite plates described in this invention, the radius r of the transition arc is ≥ 0.2w2, where w2 represents the extension length of the horizontal portion, and its unit parameter is mm.

[0020] For implementations with a smaller rectangular bevel thickness b3 (e.g., the implementation described above where b3 is 0.2mm ≤ b3 ≤ 0.5b2), since this implementation would result in a significant limitation on the heat input during carbon steel weld application, it is preferable to control the radius r of the transition arc to be ≥ 0.2w2 in order to avoid incomplete fusion welding defects under these conditions.

[0021] Furthermore, in the welding method for nickel-based alloy composite plates described in this invention, in the step of performing self-fusion welding of the nickel-based alloy composite layer using laser welding: the laser spot diameter is ≤1mm, the laser power is controlled at 4.0-5.0KW, the welding speed is 2.5-3.0m / min, and the positive defocusing amount is 0-5mm.

[0022] Furthermore, in the welding method for nickel-based alloy composite plates described in this invention, in the step of using laser welding to perform filler wire welding on the transition layer, the diameter of the laser spot used is ≤1mm.

[0023] Furthermore, in the welding method for nickel-based alloy composite plates described in this invention, in the step of using laser welding to perform filler wire welding on the transition layer: the laser power is controlled to be 5.0-6.0KW, the welding speed is 4.0-5.0m / min, the positive defocusing amount is 5-10mm, the wire feeding speed is 0.5-1.0m / min, and the wire feeding angle is 30-45°.

[0024] In this implementation, with the specially designed bevel shape, the transition layer weld will melt down part of the composite layer weld, which can ultimately ensure that the ratio of carbon steel components (including carbon steel base material and carbon steel welding wire) and nickel-based alloy components melted into the transition layer weld does not exceed 1:1, and the transition layer weld can still maintain the parent phase full austenitic structure.

[0025] Furthermore, in the welding method for nickel-based alloy composite plates described in this invention, in the step of welding the substrate layer using hot-wire pulsed tungsten inert gas welding: the welding voltage is controlled at 13.0-15.0V, the peak current at 160-200A, the base current at 80-120A, the duty cycle at 50-80%, the pulse frequency at 5-10Hz, the hot-wire current at 80-100A, the welding speed at 150-180mm / min, and the wire feed speed at 2.6-3.2m / min.

[0026] In this implementation, the transition layer weld obtained by using a special process can ensure that the dilution rate of the carbon steel weld, especially the carbon steel weld bead in direct contact with the transition layer, is less than 2.0% relative to the composite layer weld, and the microstructure will not be transformed into martensitic microstructure as a whole.

[0027] The welding method for nickel-based alloy composite plates described in this invention has the following advantages and beneficial effects compared to the prior art:

[0028] The welding method described in this invention achieves composite layer weld connection through laser self-fusion welding. At the same time, through special groove design and welding process, carbon steel welding materials can be used to achieve a good transition from nickel-based alloy to the substrate layer structure, resulting in a reliable transition layer weld.

[0029] The welding method described in this invention avoids overall martensite formation in carbon steel welds caused by excessive melting of weld metal elements in the transition layer. This allows for reliable connection of nickel-based alloy composite plates without the need for nickel-based alloy welding materials, reducing welding costs and generating considerable economic benefits. Attached Figure Description

[0030] Figure 1 The diagram schematically illustrates the bevel used in the welding method of the nickel-based alloy composite plate described in this invention.

[0031] Figure 2 The image shows the morphology of the welded joint of a nickel-based alloy composite plate prepared by the welding method of Example 1 of the present invention after being etched with nitric acid alcohol.

[0032] Figure 3 The image shows a metallographic photograph of the weld joint of a nickel-based alloy composite plate prepared by the welding method of Example 1 of the present invention, after etching with nitric acid alcohol, at the weld joint interface of the transition layer / carbon steel substrate layer. Detailed Implementation

[0033] The welding method of the nickel-based alloy composite plate of the present invention will be further explained and described below with reference to specific embodiments and accompanying drawings. However, such explanation and description do not constitute an improper limitation on the technical solution of the present invention.

[0034] The purpose of this invention is to provide a welding method for nickel-based alloy composite plates. 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 substrate layer 1 and a nickel-based alloy composite layer 2, and a transition layer is provided at the interface between the 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.

[0035] In one specific embodiment, a nickel-based alloy composite plate with the grade Incoloy825 / X52 can be used, i.e., the substrate layer material is X52 and the nickel-based alloy composite layer material is Incoloy825. 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.

[0036] In some embodiments, the welding method for nickel-based alloy composite plates includes the steps of:

[0037] 100: Processing at the welding position of the two spliced ​​nickel-based alloy composite plates A and B as follows Figure 1 The bevel shown is described. Specifically, a composite bevel is machined on the welding section of the nickel-based alloy composite plate at a position corresponding to the substrate layer. This composite bevel includes a vertically inclined portion 6, a horizontal portion 8, and a transition arc 7 located between the vertically inclined portion and the horizontal portion, wherein the extension length of the horizontal portion is... Figure 1 In this context, "w2" is used to represent the shape. A rectangular bevel is made on the weld section of the nickel-based alloy corresponding to the transition layer. The width of one side of this rectangular bevel is within... Figure 1 In the diagram, w1 / 2 represents the thickness of a rectangular bevel. Figure 1 The term b3 indicates that no bevel is machined on the welding section of the nickel-based alloy composite plate corresponding to the position of the nickel-based alloy composite layer, meaning that the welding surface of the nickel-based alloy composite layer is a vertical plane.

[0038] 200: Laser welding is used to perform self-fusion welding on the nickel-based alloy composite layer to form the composite layer weld 3.

[0039] 300: Using carbon steel welding wire that matches the base layer, laser welding is used to filler wire welding the transition layer to form the transition layer weld 4.

[0040] 400: Using carbon steel welding wire that matches the carbon steel substrate layer, hot wire pulse tungsten inert gas welding is used to filler wire welding of the carbon steel substrate layer to form substrate layer weld 5.

[0041] Preferably, in some embodiments, the width of one side of the rectangular groove w1 / 2 is greater than or equal to the laser spot radius of the laser welding, that is, the total width w1 of the two rectangular grooves formed by the two spliced ​​nickel-based alloy composite plates A and B is greater than or equal to the laser spot diameter of the laser welding. This design can ensure that the laser self-fusion welding of the nickel-based alloy composite layer weld is successfully completed without melting the carbon steel substrate.

[0042] Preferably, in some embodiments, the range of b3, i.e. the thickness of the rectangular bevel, can be limited to 0.2mm ≤ b3 ≤ 0.5b2, where b2 represents the distance from the surface of the nickel-based alloy composite layer to its bonding interface with the substrate layer, and its unit parameter is mm.

[0043] Preferably, in some embodiments, the angle α between the vertically inclined portion and the vertical direction is ≥ (1.5b1)°, where b1 represents the distance from the surface of the substrate layer to its interface with the nickel-based alloy composite layer, with the unit parameter being mm. In this embodiment, controlling the angle α facilitates the subsequent hot-wire pulse tungsten inert gas welding operation.

[0044] Preferably, in some embodiments, the extension length w2 of the horizontal portion is greater than or equal to (5 + 0.1b1), where b1 represents the distance from the surface of the substrate layer to the interface between it and the nickel-based alloy composite layer, and the unit parameter is mm.

[0045] Preferably, in some embodiments, the radius r of the transition arc is ≥ 0.2w², where w² represents the extension length of the horizontal portion, with units of mm. This embodiment avoids defects caused by incomplete fusion welding.

[0046] Preferably, in some embodiments, in step 200, laser autofusion welding is used to form the composite layer weld 3. The laser spot diameter is ≤1mm, the laser power can be controlled to be 4.0-5.0KW, the welding speed is 2.5-3.0m / min, and the positive defocusing amount is 0-5mm.

[0047] In step 300, laser filler wire welding is used to weld the transition layer weld 4. The filler metal can be carbon steel welding material that matches the properties of the base material of the substrate layer, such as ER50-6. The laser spot diameter is ≤1mm, the laser power can be controlled at 5.0-6.0KW, the welding speed is 4.0-5.0m / min, the positive defocusing amount is 5-10mm, the wire feeding speed is 0.5-1.0m / min, and the wire feeding angle is 30-45°.

[0048] By employing this preferred embodiment and in conjunction with a specially designed bevel, the transition layer weld will melt down part of the composite layer weld, ultimately ensuring that the ratio of carbon steel components (including carbon steel base metal and carbon steel welding wire) to nickel-based alloy components melted into the transition layer weld does not exceed 1:1, and the transition layer weld can still maintain a fully austenitic microstructure.

[0049] In step 400, carbon steel weld wire ER50-6, which is matched with the base material of the substrate layer, is used to weld the carbon steel weld 5. The welding method is hot wire pulse tungsten inert gas welding, and the welding voltage is controlled at 13.0-15.0V, the peak current is 160-200A, the base current is 80-120A, the duty cycle is 50-80%, the pulse frequency is 5-10Hz, the hot wire current is 80-100A, the welding speed is 150-180mm / min, and the wire feed speed is 2.6-3.2m / min.

[0050] By employing this preferred embodiment, the transition layer weld obtained through a special process ensures that the dilution rate of the carbon steel weld, especially the carbon steel weld bead in direct contact with the transition layer, relative to the composite layer weld is less than 2.0%, and the microstructure does not transform into martensitic microstructure as a whole.

[0051] To further illustrate 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.

[0052] Table 1.

[0053]

[0054] Table 2 lists the welding process parameters used in step 200 of forming the composite layer weld in preferred embodiments 1-5 of the present invention.

[0055] Table 2.

[0056] serial number Laser spot diameter (mm) Laser power (KW) Welding speed (m / min) Defocusing amount (mm) Example 1 0.5 4.5 2.6 0 Example 2 0.8 4.0 2.5 +3 Example 3 0.5 5.0 3.0 0 Example 4 0.8 4.8 2.6 +5 Example 5 1.0 4.6 2.8 0

[0057] Table 3 lists the welding process parameters used in step 300 of forming the transition layer weld in preferred embodiments 1-5 of the present invention.

[0058] Table 3.

[0059]

[0060]

[0061] Table 4 lists the welding process parameters used in step 400 of forming the substrate layer weld in preferred embodiments 1-5 of the present invention.

[0062] Table 4.

[0063]

[0064] In addition, to demonstrate the implementation effect of the preferred embodiment, Table 5 lists the Cr content of each layer of the base material and weld of the nickel-based alloy composite plate obtained by welding according to Embodiment 1 of the present invention. By calculation, it can be found that the dilution rate of the transition layer weld bead relative to the composite layer weld bead is 58.96%, and the dilution rate of the carbon steel weld bead in direct contact with the transition layer relative to the composite layer weld bead is 1.86% (less than 2.0%). Therefore, the formation of martensitic structure in the carbon steel weld bead can be avoided.

[0065] Table 5.

[0066]

[0067]

[0068] Figure 2 The image shows the morphology of the welded joint of the composite plate prepared by the welding method of Embodiment 1 of the present invention after being etched by nitric acid alcohol.

[0069] from Figure 2 As can be seen from the data, the welded joint is well bonded, indicating that the method of the present invention can achieve effective connection of nickel-based alloy composite plates.

[0070] Figure 3 The image shows a metallographic photograph of the transition layer / carbon steel weld joint of the composite plate prepared by the welding method of Embodiment 1 of the present invention after etching with nitric acid alcohol.

[0071] from Figure 3 It can be seen that the transition layer weld cannot be corroded by nitric acid alcohol, indicating that it still retains the austenitic corrosion-resistant structure of the base material. However, a large number of ferrite grains are visible in the carbon steel weld adjacent to the transition layer, and no obvious martensite structure is observed. This indicates that the invention objective has been achieved, that is, the transition of the microstructure / composition of the transition layer weld to the carbon steel weld in the nickel-based alloy composite plate is completed using carbon steel welding materials, and the joint connection of the composite plate is reliable.

[0072] 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.

[0073] 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 a nickel-based alloy composite plate, the nickel-based alloy composite plate comprising 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; characterized in that, The welding method includes the following steps: A composite bevel is machined on the welding section of the nickel-based alloy composite plate at the position corresponding to the base material layer. The composite bevel includes a vertically inclined portion, a horizontal portion, and a transition arc between the vertically inclined portion and the horizontal portion. A rectangular bevel is opened 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. The single-side width w1 / 2 of the rectangular bevel is greater than or equal to the laser spot radius of the laser welding. The thickness b3 of the rectangular bevel satisfies 0.2mm≤b3≤0.5b2, where b2 represents the distance from the surface of the nickel-based alloy composite layer to its interface with the base material layer, and its unit parameter is mm. The extension length w2 of the horizontal portion is greater than or equal to (5+0.1b1), where b1 represents the distance from the surface of the base material layer to its interface with the nickel-based alloy composite layer, and its unit parameter is mm. Laser welding was used to perform self-fusion welding on nickel-based alloy composite layers; Using carbon steel welding wire that matches the base layer, laser welding is used to filler wire welding the transition layer; The substrate layer was welded using hot-wire pulsed tungsten inert gas welding.

2. The welding method for nickel-based alloy composite plates as described in claim 1, characterized in that, The angle α between the vertically inclined portion and the vertical direction is ≥ (1.5b1)°, where b1 represents the distance from the surface of the substrate layer to the interface between it and the nickel-based alloy composite layer, and its unit parameter is mm.

3. The welding method for nickel-based alloy composite plates as described in claim 1, characterized in that, The radius r of the transition arc is greater than or equal to 0.2w2, where w2 represents the extension length of the horizontal part, and its unit parameter is mm.

4. The welding method for nickel-based alloy composite plates as described in claim 1, characterized in that, In the step of self-fusion welding of nickel-based alloy composite layers using laser welding: the laser spot diameter is ≤1mm, the laser power is controlled at 4.0-5.0KW, the welding speed is 2.5-3.0m / min, and the positive defocusing amount is 0-5mm.

5. The welding method for nickel-based alloy composite plates as described in claim 1, characterized in that, In the step of using laser welding to perform filler wire welding on the transition layer, the diameter of the laser spot used is ≤1mm.

6. The welding method for nickel-based alloy composite plates as described in claim 1, characterized in that, In the step of using laser welding to perform filler wire welding on the transition layer: the laser power is controlled at 5.0-6.0KW, the welding speed is 4.0-5.0m / min, the positive defocusing amount is 5-10mm, the wire feeding speed is 0.5-1.0m / min, and the wire feeding angle is 30-45°.

7. The welding method for nickel-based alloy composite plates as described in claim 1, characterized in that, In the step of welding the substrate layer using hot-wire pulsed tungsten inert gas welding: the welding voltage is controlled at 13.0-15.0V, the peak current is 160-200A, the base current is 80-120A, the duty cycle is 50-80%, the pulse frequency is 5-10Hz, the hot wire current is 80-100A, the welding speed is 150-180mm / min, and the wire feed speed is 2.6-3.2m / min.

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