Precipitation strengthening type cast high-temperature alloy stack-welded joint and hybrid welding manufacturing method for reducing liquidation crack sensitivity

Abstract

The invention discloses a precipitation strengthening type cast high-temperature alloy heap-welded joint and a composite welding manufacturing method for reducing liquidation crack sensitivity, and belongs to the technical field of welding, and the method comprises the following steps: firstly, carrying out solid solution slow cooling and heating treatment on a casting alloy, and then, carrying out brazing on the casting alloy by using nickel-based brazing filler metal, and finally, surfacing welding is conducted on the brazing layer through a welding material, and the precipitation strengthening type cast high-temperature alloy surfacing welding joint is obtained. The structure and the performance of the surface layer / secondary surface layer of the welding part of the casting can be effectively improved through brazing and melting surfacing, double isolation layers of a brazing layer and a surfacing layer are formed, and the resistance of the brazing layer and the surfacing layer to welding hot cracks is improved; meanwhile, due to the fact that the brazing temperature is low, the residual stress of the formed brazed / surfaced joint is small, the sensitivity of welding liquefaction cracks is finally reduced, and a fusion welding joint with good quality is formed.

Description

Technical Field

[0001] This invention belongs to the field of welding technology, specifically relating to a precipitation-strengthened cast high-temperature alloy welded joint and a composite welding manufacturing method for reducing liquefaction crack sensitivity. Background Technology

[0002] With the development of 700℃ ultra-supercritical coal-fired power generation technology, the service temperature of key high-temperature components in boilers has reached 700-750℃. Solid solution-strengthened high-temperature alloys are difficult to use at this temperature, necessitating the selection of precipitation-strengthened high-temperature alloys. Precipitation-strengthened nickel-based / nickel-iron-based high-temperature alloys, due to their excellent high-temperature performance and oxidation resistance, are considered as manufacturing materials for large-size, heavy-tonnage, and complex-thickness castings such as valve bodies and cylinders in advanced 650℃-class ultra-supercritical thermal power generating units. These high-temperature alloys maintain stable mechanical properties and corrosion resistance under extreme high-temperature environments, thus ensuring the long-term stable operation of the generating units. However, due to the numerous difficulties in the fusion welding process of precipitation-strengthened cast nickel-based / nickel-iron-based high-temperature alloys, existing techniques mainly rely on specific welding structure designs and optimized welding parameters. Traditional welding methods often suffer from complex processes and high costs when dealing with fusion welding cracks in these high-temperature alloys. Although advanced welding technologies such as laser welding and electron beam welding have been adopted, while reducing welding heat input, these methods still struggle to effectively solve the problem of welding hot cracking.

[0003] Furthermore, most post-weld heat treatments used in existing technologies involve aging the γ' phase to allow the heat-affected zone (HAZ) to re-precipitate strengthening phases. This method easily leads to cracks in the HAZ of thick-walled, large-sized components. Simultaneously, due to the high coefficient of thermal expansion and low thermal conductivity of these high-temperature alloys, the cast microstructure exhibits coarse grains and a significant tendency for compositional segregation, resulting in a high susceptibility to hot cracking at the fusion line and in the HAZ during welding, severely impacting the quality and performance of the welded joint.

[0004] Several invention patents have been issued to address the issues of reducing the hot cracking tendency of precipitation-strengthened cast superalloy welded joints, improving the joint's mechanical properties, and extending its service life. CN112872652A discloses a Ni-based superalloy welding wire with high Al, Ti, and Ta content, its preparation method, and its application. This invention, by adding high levels of these three strengthening elements to the welding wire, obtains a sufficient amount of strengthening phases, significantly improving the strength of the welded joint. Simultaneously, through the synergistic effect with other elements, it ensures a small difference in the coefficient of thermal expansion between the welding wire and the nickel-based cast superalloy, reducing crack sensitivity and thus obtaining a welded joint with no cracks or a low number of cracks. However, this invention still requires further optimization in terms of the welding wire's composition and preparation process to improve the performance and durability of the welded joint. CN107470766A discloses a method for improving the weldability of iron-nickel-based precipitation-strengthened austenitic alloys through grain boundary serration treatment. This method employs controlled-cold heat treatment to induce serration of high-energy grain boundaries, altering the distribution of boron and titanium elements segregated at these boundaries, increasing resistance to grain boundary liquefaction crack formation, and improving the weldability of the alloy. However, the process parameters of the controlled-cold heat treatment still require further optimization to obtain a superior serrated grain boundary structure and better weldability.

[0005] Therefore, in the surfacing and fusion welding of precipitation-strengthened cast nickel-based / nickel-iron-based superalloys, there is an urgent need for a welding method that can provide a strong connection and effectively reduce the susceptibility of the joint to liquefaction cracking, in order to overcome the relevant welding technical challenges. Summary of the Invention

[0006] In order to overcome the shortcomings of the prior art, the present invention aims to provide a precipitation-strengthened cast high-temperature alloy weld joint and a composite welding manufacturing method to reduce the sensitivity to liquefaction cracking, so as to solve the technical problems of the high hot cracking tendency of existing cast nickel-iron-based high-temperature alloy casting weld joints, and the large shrinkage, deformation and residual stress generated in the joint after welding thermal cycle.

[0007] To achieve the above objectives, the present invention employs the following technical solution:

[0008] This invention discloses a composite welding manufacturing method for reducing the sensitivity to liquefaction cracking of precipitation-strengthened cast high-temperature alloy welded joints, comprising: firstly performing solution cooling heat treatment on the cast alloy, then brazing the cast alloy using a nickel-based brazing filler metal, and finally using welding material to deposit welds on the brazing layer to obtain a precipitation-strengthened cast high-temperature alloy welded joint.

[0009] Preferably, the casting alloy is a precipitation-strengthened nickel-iron-based superalloy, comprising, by mass percentage: Fe: 40%-48%, Cr: 14%-18%, Mo: 0.2%-1.0%, W: 0.3%-1.0%, 0.5%≤Mo+W≤1.4%, Ti: 1.0%-2.1%, Al: 1.0%-1.8%, Nb≤0.1%, Zr≤0.03%, C: 0.03%-0.1%, B: ≤0.007%, P: ≤0.01%, with the remainder being Ni.

[0010] More preferably, the Fe+Ni content is greater than 50% by mass percentage.

[0011] More preferably, the Al+Ti content is ≥2.0% by mass percentage.

[0012] More preferably, the strengthening phase of the precipitation-strengthened nickel-iron-based superalloy is mainly γ'-Ni3(Al,Ti).

[0013] Preferably, the solution cooling heat treatment temperature is 1000-1050℃ and the time is 1-3h.

[0014] Preferably, the cooling method for the solution cooling heat treatment is furnace cooling; after the solution cooling heat treatment, the casting alloy is in a sub-aged or aged state.

[0015] Preferably, the solidus of the nickel-based brazing filler metal is 970°C and the liquidus is 1000°C; the nickel-based brazing filler metal is in the form of foil or transfer tape; and the brazing method is furnace brazing or flame brazing.

[0016] Preferably, the welding method is at least one of tungsten inert gas welding, hot wire tungsten inert gas welding, cold metal transfer welding, gas shielded welding, and laser welding.

[0017] The present invention also discloses a precipitation-strengthened cast high-temperature alloy welded joint prepared by the above-mentioned composite welding manufacturing method for reducing the sensitivity to liquefaction cracking, comprising a casting alloy, a brazing layer at the welding part of the casting alloy, and a weld overlay layer welded on the brazing layer.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] This invention discloses a composite welding manufacturing method for reducing the susceptibility to liquefaction cracking in precipitation-strengthened cast high-temperature alloy welded joints. First, the cast alloy undergoes solution cooling heat treatment. This treatment eliminates internal stress and segregation in the casting, ensuring a more uniform distribution of alloying elements and providing a stable microstructure for subsequent brazing and weld overlay, thus reducing crack susceptibility during welding. Next, the surface of the welded area of ​​the cast alloy is brazed. The casting body at the welded area does not melt; the molten brazing filler metal wets the casting alloy through element diffusion, forming a firmly bonded brazed layer. This brazed layer effectively isolates the casting body from the weld overlay, thereby enhancing resistance to welding hot cracking. Finally, weld overlay is performed on the brazed layer to form a welded joint. By using appropriate welding materials and welding processes, precipitation-strengthened cast high-temperature alloy welded joints with excellent mechanical properties and crack resistance can be obtained. This invention improves the elemental distribution at the surface / subsurface grain boundaries of the welded area of ​​the casting body, forming a double isolation layer of brazed and weld overlay layers, thereby reducing the liquefaction crack susceptibility of the precipitation-strengthened cast high-temperature alloy welded joint.

[0020] Furthermore, the casting alloy is a precipitation-strengthened nickel-iron-based high-temperature alloy, which can fully utilize its high-temperature strength, toughness, and creep resistance to improve the performance of the welded joint at high temperatures.

[0021] Furthermore, the solution heat treatment temperature is 1000-1050℃; the time is 1-3h; and the cooling method is furnace cooling. Using this temperature, time range, and cooling method for solution heat treatment can ensure that the internal stress and segregation in the casting alloy are effectively eliminated, while avoiding overheating that would lead to a decline in alloy performance.

[0022] Furthermore, the brazing method is a method that can wet the alloy surface of the welding part of the casting, form a brazing isolation layer with a thickness of <1mm and be firmly connected to the casting body; it can effectively improve the microstructure and properties of the surface / subsurface layer of the welding part and enhance its resistance to welding hot cracking.

[0023] Furthermore, the welding method is a fusion welding method with low welding heat input; this can reduce the thermal impact on the casting alloy and reduce the crack sensitivity of the weld joint.

[0024] Furthermore, the welding methods include tungsten inert gas welding (TIG), hot-wire TIG welding, cold metal transfer welding, gas shielded welding, and laser welding; these welding methods can all achieve high-quality welded joints with stable welding processes and good joint performance.

[0025] This invention also discloses a precipitation-strengthened cast high-temperature alloy welded joint prepared by the aforementioned composite welding manufacturing method for reducing liquefaction crack sensitivity. This welded joint exhibits excellent resistance to hot cracking and can meet the requirements for use in harsh environments such as high temperature and high pressure. It effectively reduces the tendency of the precipitation-strengthened cast high-temperature alloy welded joint to hot crack, improving the mechanical properties and service life of the joint. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the precipitation-strengthened cast high-temperature alloy welded joint disclosed in this invention;

[0027] Figure 2 The image shows a metallographic photograph of the precipitation-strengthened cast high-temperature alloy disclosed in Embodiment 3 of this invention after brazing.

[0028] Figure 3 This is a metallographic photograph of the TIG weld joint of the precipitation-strengthened cast high-temperature alloy disclosed in Embodiment 3 of the present invention after brazing. Detailed Implementation

[0029] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined to form new technical solutions.

[0031] Unless otherwise specified, all the technical features and preferred features mentioned herein can be combined to form new technical solutions.

[0032] In this invention, unless otherwise specified, percentage (%) or parts refer to weight percentage or parts relative to the composition.

[0033] Unless otherwise specified, the components or preferred components involved in this invention can be combined with each other to form new technical solutions.

[0034] In this invention, unless otherwise specified, the numerical range "a~b" represents an abbreviation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "6~22" means that all real numbers between "6~22" have been listed in this document, and "6~22" is simply an abbreviation of these numerical combinations.

[0035] The "scope" disclosed in this invention can be in the form of a lower limit and an upper limit, and can be one or more lower limits and one or more upper limits, respectively.

[0036] In this invention, the term "and / or" as used herein refers to any combination of one or more of the associated listed items, as well as all possible combinations, and includes such combinations.

[0037] In this invention, unless otherwise stated, the various reaction or operation steps may be performed sequentially or in a particular order. Preferably, the reaction methods described herein are performed sequentially.

[0038] Unless otherwise stated, the technical and scientific terms used herein have the same meanings as those familiar to those skilled in the art. Furthermore, any methods or materials similar to or equivalent to those described herein may also be used in this invention.

[0039] This invention provides a composite welding manufacturing method for reducing the sensitivity to liquefaction cracking in precipitation-strengthened cast high-temperature alloy welded joints, comprising: first performing a solution cooling heat treatment on the cast alloy, then brazing the cast alloy with a brazing filler metal, and finally using welding material to deposit welds on the brazing layer to obtain a precipitation-strengthened cast high-temperature alloy welded joint.

[0040] Solution cooling is a crucial step in the manufacturing process of cast high-temperature alloys. Through solution cooling, internal stresses in the casting alloy can be eliminated, segregation reduced, and alloying elements more uniformly distributed, providing a stable microstructure for subsequent machining and welding. Furthermore, solution cooling improves the corrosion resistance and high-temperature strength of the casting alloy, ensuring the long-term performance of welded joints.

[0041] Brazing is an important step in further improving the weldability of alloy welded parts in castings. Through brazing, the molten filler metal wets and improves the surface quality of the alloy at the welded part of the casting through element diffusion, forming a brazing layer with a thickness of <1mm that is firmly connected to the casting body. This brazing layer effectively isolates the casting body from the weld overlay. At the same time, due to the low brazing temperature, the residual stress of the joint is small, thereby enhancing the resistance to welding hot cracking and further reducing the tendency to crack.

[0042] Nickel-based brazing filler metal is a commonly used nickel-based brazing filler metal for precipitation-strengthened high-temperature alloys. The grade is BNi2. The solidus and liquidus of the filler metal are 970℃ and 1000℃, respectively. The filler metal can be in the form of foil or transfer tape. The brazing methods are commonly used furnace brazing or flame brazing.

[0043] Overlay welding is the process of forming one or more layers of welding material with excellent properties on a brazed layer. By using appropriate welding materials and welding processes, overlay welding can be performed on a brazed layer to produce welded joints with high strength, high toughness, and good corrosion resistance, which can meet the requirements for use in harsh environments such as high temperature and high pressure.

[0044] The casting alloy is a precipitation-strengthened nickel-iron-based superalloy, comprising, by mass percentage: Fe: 40%-48%, Cr: 14%-18%, Mo: 0.2%-1.0%, W: 0.3%-1.0%, 0.5%≤Mo+W≤1.4%, Ti: 1.0%-2.1%, Al: 1.0%-1.8%, Nb≤0.1%, Zr≤0.03%, C: 0.03%-0.1%, B: ≤0.007%, P: ≤0.01%, with the remainder being Ni.

[0045] Precipitation-strengthened nickel-iron-based superalloys were chosen as the casting alloy because these alloys possess excellent high-temperature strength, toughness, and creep resistance. Through rational composition design and heat treatment processes, the potential properties of these alloys can be further utilized, improving the overall quality and service life of the welded joints.

[0046] By precisely controlling the content of each element, casting alloys with excellent properties can be obtained. For example, Fe and Ni are the main components of the alloy, and they together determine the basic properties of the alloy. The addition of Cr can improve the alloy's corrosion resistance and oxidation resistance. Ti and Al are key elements in the formation of the γ' strengthening phase, which can significantly improve the alloy's high-temperature strength and creep resistance. The addition of trace elements such as W, Si, C, and B can further adjust the microstructure and properties of the alloy to meet specific application requirements.

[0047] By mass percentage, Fe+Ni > 50%.

[0048] By ensuring that the total Fe and Ni content exceeds 50%, sufficient high-temperature strength and toughness of the alloy can be guaranteed. Simultaneously, this compositional design also improves the alloy's corrosion resistance and oxidation resistance, ensuring the long-term performance of the welded joint.

[0049] By mass percentage, Al + Ti ≥ 2.0%.

[0050] Al and Ti are key elements for the formation of the γ' strengthening phase, which can significantly improve the high-temperature strength and creep properties of the alloy. By ensuring that the total content of Al and Ti is not less than 2.0%, the alloy can be guaranteed to have excellent precipitation strengthening effect, further improving the overall performance of the welded joint.

[0051] The strengthening phase of precipitation-strengthened nickel-iron-based superalloys is mainly γ'-Ni3(Al,Ti).

[0052] γ'-Ni3(Al,Ti) is a precipitated strengthening phase with excellent high-temperature strength. By ensuring that the main strengthening phase in the casting alloy is γ'-Ni3(Al,Ti), the high-temperature strength and creep properties of the alloy can be significantly improved, ensuring the long-term performance of the welded joint.

[0053] The solution heat treatment temperature for the casting alloy is 1000-1050℃; the time is 1-3h; the cooling method is furnace cooling; after solution slow cooling heat treatment, the casting alloy is in a sub-aged / aged state.

[0054] By precisely controlling the temperature and time of solution heat treatment, casting alloys with stable microstructure and properties can be obtained. Solution heat treatment within this temperature, time range, and cooling method ensures a uniform distribution of alloying elements in the casting alloy, eliminates internal stress and segregation, and provides a good foundation for subsequent surface modification and welding.

[0055] After solution cooling, the alloy element distribution of under-aged / aged castings is more uniform, and the elimination of internal stress and segregation is more effective, which is beneficial to reducing the susceptibility to cracking during the welding process.

[0056] Brazing of the welded parts is a method that wets the alloy surface of the welded part of the casting, forms a brazing isolation layer with a thickness of <1mm and can be firmly connected to the casting body; it can effectively improve the microstructure and properties of the surface / subsurface layer of the welded part, reduce the residual stress of the joint, and further improve its resistance to welding hot cracking.

[0057] The surfacing welding method is a fusion welding method with low welding heat input, such as tungsten inert gas welding, hot wire tungsten inert gas welding, cold metal transfer welding, gas shielded welding, laser welding, etc.

[0058] Choosing a fusion welding method with lower heat input for surfacing can reduce the thermal impact on the casting alloy and decrease the susceptibility of the weld joint to cracking. At the same time, lower heat input can preserve the original microstructure and properties of the casting alloy, ensuring the overall quality of the weld joint.

[0059] TIG welding, hot-wire TIG welding, cold metal transfer welding, gas shielded welding, and laser welding are all commonly used fusion welding methods that can form high-quality weld joints. Choosing these welding methods for weld joints ensures the strength and toughness of the weld joints, meeting the requirements for use in harsh environments such as high temperature and high pressure.

[0060] This invention also discloses the aforementioned composite welding method for reducing the liquefaction crack sensitivity of precipitation-strengthened cast high-temperature alloy welded joints. This welded joint exhibits excellent resistance to hot cracking and can meet the requirements for use in harsh environments such as high temperature and high pressure. It effectively reduces the tendency for hot cracking in precipitation-strengthened cast high-temperature alloy welded joints, improving the mechanical properties and service life of the joint.

[0061] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0062] Example 1

[0063] (1) The under-aged 45Fe-33.91Ni-16Cr-1.5Al-2.1Ti-0.5Mo-0.5W-0.3Si-0.1Nb-0.03Zr-0.05C-0.005B-0.005P (wt.%) alloy test plate was used as the welding test material. The test plate specifications were 200mm in length, 150mm in width, and 20mm in thickness. The solution heat treatment temperature was 1000±10℃, and the heat treatment time was 3h before furnace cooling.

[0064] (2) Then, in-furnace brazing was performed on the surface of the test plate. The brazing material was foil strip nickel-based brazing material (grade BNi2, BNi82CrSiBFe). The brazing temperature was 1020℃, the brazing time was 5min, and the cooling method was furnace cooling.

[0065] (3) Next, surfacing is performed on the brazing layer. The first surfacing layer is welded using tungsten inert gas welding with ERNiCrCoMo-1 welding wire of Φ2.4mm diameter; the parameters are: current 90A, voltage 10V, and surfacing speed 8cm / min. The second surfacing layer is welded using cold metal transfer welding with ERNiCrCoMo-1 welding wire of Φ1.2mm diameter; the parameters are: current 250A, voltage 25V, welding speed 25cm / min, and interlayer / pass temperature 50℃.

[0066] Example 2

[0067] (1) The under-aged 45Fe-31.91Ni-18Cr-1.5Al-2.1Ti-0.5Mo-0.5W-0.3Si-0.1Nb-0.03Zr-0.05C-0.005B-0.005P (wt.%) alloy test plate was used as the welding test material. The test plate specifications were 200mm in length, 150mm in width, and 20mm in thickness. The solution heat treatment temperature was 1050±10℃, and the heat treatment time was 3h before cooling with the furnace.

[0068] (2) Subsequently, flame brazing was performed on the surface of the test plate. The brazing filler metal was nickel-based transfer adhesive brazing filler metal (grade BNi2, BNi82CrSiBFe). The brazing temperature was 1050℃, the brazing time was 10min, and the cooling method was furnace cooling.

[0069] (3) Next, surfacing is performed on the brazing layer. The first surfacing layer is surfacing using automatic wire feeding tungsten inert gas welding with ERNiCrCoMo-1 wire and a diameter of Φ1.2mm. The parameters are: current 140A, voltage 12V, and surfacing speed 12cm / min. The second surfacing layer is surfacing using hot wire tungsten inert gas welding with ERNiCrCoMo-1 wire and a diameter of Φ1.0mm. The parameters are: current 250A, voltage 25V, welding speed 25cm / min, and interlayer / pass temperature 50℃.

[0070] Example 3

[0071] (1) The under-aged 48Fe-32.91Ni-14Cr-1.5Al-2.1Ti-0.5Mo-0.5W-0.3Si-0.1Nb-0.03Zr-0.05C-0.005B-0.005P (wt.%) alloy test plate was used as the welding test material. The test plate specifications were 200mm in length, 150mm in width, and 20mm in thickness. The solution heat treatment temperature was 1020±10℃, and the heat treatment time was 3h before cooling with the furnace.

[0072] (2) Subsequently, in-furnace brazing was performed on the surface of the test plate. The brazing filler metal was nickel-based transfer adhesive brazing filler metal (grade BNi2, BNi82CrSiBFe). The brazing temperature was 1020℃, the brazing time was 5min, and the cooling method was furnace cooling.

[0073] (3) Next, welding is carried out on the brazing layer. The entire welding layer is welded by automatic wire feeding tungsten inert gas welding. The welding wire is ERNiCrCoMo-1 with a diameter of Φ1.2mm. The parameters are: current 140A, voltage 12V, welding speed 12cm / min, and layer / pass temperature 40℃.

[0074] See Figure 1This is a schematic diagram of the precipitation-strengthened cast high-temperature alloy weld joint disclosed in this invention. As shown in the diagram, the precipitation-strengthened cast high-temperature alloy weld joint includes a casting body at the bottom, a brazing layer welded to the casting body, and a weld overlay layer welded to the brazing layer. This invention effectively improves the microstructure and properties of the surface / subsurface layers of the casting weld area through brazing and fusion welding, enhancing its resistance to welding hot cracking. Simultaneously, due to the low brazing temperature, the resulting brazed and welded joints have low residual stress, ultimately reducing the susceptibility to welding liquefaction cracking and forming a high-quality fusion weld joint.

[0075] See Figure 2 The image shown is a metallographic photograph of the precipitation-strengthened cast high-temperature alloy after brazing, as disclosed in Embodiment 3 of this invention; see also Figure 3 The image shows a metallographic photograph of the TIG-bonded joint of the precipitation-strengthened cast high-temperature alloy disclosed in Embodiment 3 of this invention after brazing; from Figure 2 and Figure 3 As can be seen, no welding hot cracks were found in the fusion line and heat-affected zone of the weld joints obtained after brazing and subsequent fusion welding.

[0076] Example 4

[0077] (1) The under-aged 40Fe-38.91Ni-16Cr-1.5Al-2.1Ti-0.5Mo-0.5W-0.3Si-0.1Nb-0.03Zr-0.05C-0.005B-0.005P (wt.%) alloy test plate was used as the welding test material. The test plate specifications were 200mm in length, 150mm in width, and 20mm in thickness. The solution heat treatment temperature was 1000±10℃, and the heat treatment time was 2h before furnace cooling.

[0078] (2) Then, in-furnace brazing was performed on the surface of the test plate. The brazing filler metal was nickel-based transfer adhesive brazing filler metal (grade BNi2, BNi82CrSiBFe). The brazing temperature was 1000℃, the brazing time was 10min, and the cooling method was furnace cooling.

[0079] (3) Next, surfacing is performed on the brazing layer. The first surfacing layer is surfacing using tungsten inert gas welding with ERNiCrCoMo-1 welding wire, diameter Φ2.4mm, current 90A, voltage 10V, and surfacing speed 8cm / min. The second surfacing layer is surfacing using inert gas shielded welding with ERNiCrCoMo-1 welding wire, diameter Φ1.2mm, current 260A, voltage 23V, surfacing speed 50cm / min, and layer / pass temperature 50℃.

[0080] Example 5

[0081] (1) The under-aged 48Fe-32.91Ni-14Cr-1.5Al-2.1Ti-0.5Mo-0.5W-0.3Si-0.1Nb-0.03Zr-0.05C-0.005B-0.005P (wt.%) alloy test plate was used as the welding test material. The test plate specifications were 200mm in length, 150mm in width, and 20mm in thickness. The solution heat treatment temperature was 1000±10℃, and the heat treatment time was 3h before cooling with the furnace.

[0082] (2) Then flame brazing was performed on the surface of the test plate. The brazing filler metal was a foil strip nickel-based brazing filler metal (grade BNi2, BNi82CrSiBFe). The brazing temperature was 1100℃, the brazing time was 5min, and the cooling method was furnace cooling.

[0083] (3) Next, cladding is performed on the brazing layer. The first layer of cladding is laser welded with ERNiCrCoMo-1 welding wire, diameter Φ1.0mm, laser power 1kW, spot size 2.0mm, and cladding layer thickness 1.5mm. The second layer of cladding is hot wire tungsten inert gas welding with ERNiCrCoMo-1 welding wire, diameter Φ1.0mm, current 250A, voltage 25V, welding speed 25cm / min, and interlayer / pass temperature 50℃.

[0084] Example 6

[0085] (1) The under-aged 45Fe-31.91Ni-18Cr-1.5Al-2.1Ti-0.5Mo-0.5W-0.3Si-0.1Nb-0.03Zr-0.05C-0.005B-0.005P (wt.%) alloy test plate was used as the welding test material. The test plate specifications were 200mm in length, 150mm in width, and 20mm in thickness. The solution heat treatment temperature was 1050±10℃, and the heat treatment time was 3h before cooling with the furnace.

[0086] (2) Then, in-furnace brazing was performed on the test plate. The brazing filler metal was nickel-based transfer tape brazing filler metal (grade BNi2, BNi82CrSiBFe). The brazing temperature was 1100℃, the brazing time was 10min, and the cooling method was furnace cooling.

[0087] (3) Next, surfacing is performed on the brazing layer. The first surfacing layer is surfacing using automatic wire feeding tungsten inert gas welding with ERNiCrCoMo-1 wire of diameter Φ1.2mm, current 140A, voltage 12V, and surfacing speed 12cm / min. The second surfacing layer is surfacing using cold metal transfer welding with ERNiCrCoMo-1 wire of diameter Φ1.2mm, current 250A, voltage 25V, welding speed 25cm / min, and interlayer / pass temperature 50℃.

[0088] In summary, the present invention provides a precipitation-strengthened cast high-temperature alloy weld joint and a composite welding manufacturing method for reducing liquefaction crack sensitivity. By performing solution cooling heat treatment on the casting alloy, internal stress and segregation in the casting are eliminated, resulting in a more uniform distribution of alloying elements. This provides a stable microstructure for subsequent brazing and surfacing, helping to reduce crack sensitivity during welding and effectively solving the problem of high hot cracking tendency in the heat-affected zone of traditional welding techniques. Brazing the casting alloy with brazing filler metal forms a brazing isolation layer <1mm thick. This brazing layer is firmly connected to the casting body, effectively isolating the casting body from the weld layer and reducing the probability of welding hot cracking. Furthermore, due to the low brazing temperature, the resulting joint has low residual stress, further enhancing the joint's resistance to hot cracking. The brazing layer is overlaid with welding using various methods such as tungsten inert gas (TIG) welding, hot-wire TIG welding, cold metal transfer welding, and gas shielded welding to form a welded joint with excellent mechanical properties and crack resistance. This avoids the cracking problems caused by post-weld heat treatment in traditional welding techniques. Through reasonable welding materials and overlay processes, the resulting welded joint exhibits high strength, high toughness, and good corrosion resistance, meeting the requirements for use in harsh environments such as high temperature and high pressure, significantly improving the mechanical properties and service life of the welded joint. The solution cooling heat treatment process, with parameters of 1000-1050℃, 1-3h, and furnace cooling, ensures effective elimination of internal stress and segregation in the casting alloy, while avoiding overheating that could degrade alloy properties, providing a good foundation for subsequent processes. The composite welding method of this invention is simple, easy to operate, has good controllability and repeatability, reduces production costs, and has good potential for widespread application.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composite welding manufacturing method for reducing the susceptibility to liquefaction cracking in precipitation-strengthened cast high-temperature alloy welded joints, characterized in that, include: First, the casting alloy is subjected to solution cooling heat treatment, then the casting alloy is brazed using nickel-based brazing filler metal, and finally, welding material is used to build up the brazed layer to obtain a precipitation-strengthened casting high-temperature alloy welded joint.

2. The composite welding manufacturing method for reducing liquefaction crack sensitivity of precipitation-strengthened cast high-temperature alloy welded joints according to claim 1, characterized in that, The casting alloy is a precipitation-strengthened nickel-iron-based superalloy, comprising, by mass percentage: Fe: 40%-48%, Cr: 14%-18%, Mo: 0.2%-1.0%, W: 0.3%-1.0%, 0.5%≤Mo+W≤1.4%, Ti: 1.0%-2.1%, Al: 1.0%-1.8%, Nb≤0.1%, Zr≤0.03%, C: 0.03%-0.1%, B: ≤0.007%, P: ≤0.01%, with the remainder being Ni.

3. The composite welding manufacturing method for reducing liquefaction crack sensitivity of precipitation-strengthened cast high-temperature alloy welded joints according to claim 2, characterized in that, The Fe+Ni content is greater than 50% by mass percentage.

4. The composite welding manufacturing method for reducing liquefaction crack sensitivity of precipitation-strengthened cast high-temperature alloy welded joints according to claim 2, characterized in that, The Al+Ti content is ≥2.0% by mass percentage.

5. The composite welding manufacturing method for reducing liquefaction crack sensitivity of precipitation-strengthened cast high-temperature alloy welded joints according to claim 2, characterized in that, The strengthening phase of the precipitation-strengthened nickel-iron-based superalloy is mainly γ'-Ni3(Al,Ti).

6. The composite welding manufacturing method for reducing liquefaction crack sensitivity of precipitation-strengthened cast high-temperature alloy welded joints according to claim 1, characterized in that, The solution cooling heat treatment is performed at a temperature of 1000-1050℃ for 1-3 hours.

7. The composite welding manufacturing method for reducing liquefaction crack sensitivity of precipitation-strengthened cast high-temperature alloy welded joints according to claim 1, characterized in that, The cooling method for the solution cooling heat treatment is furnace cooling; after the solution cooling heat treatment, the casting alloy is in a sub-aged or aged state.

8. The composite welding manufacturing method for reducing liquefaction crack sensitivity of precipitation-strengthened cast high-temperature alloy welded joints according to claim 1, characterized in that, The nickel-based brazing filler metal has a solidus of 970°C and a liquidus of 1000°C; the nickel-based brazing filler metal is in the form of foil or transfer tape; the brazing method is furnace brazing or flame brazing.

9. The composite welding manufacturing method for reducing liquefaction crack sensitivity of precipitation-strengthened cast high-temperature alloy welded joints according to claim 1, characterized in that, The welding method is at least one of tungsten inert gas welding, hot wire tungsten inert gas welding, cold metal transfer welding, gas shielded welding, and laser welding.

10. The precipitation-strengthened cast high-temperature alloy welded joint prepared by the composite welding manufacturing method for reducing liquefaction crack sensitivity of the precipitation-strengthened cast high-temperature alloy welded joint according to any one of claims 1-9, characterized in that, This includes casting alloys, brazing layers at the welded parts of casting alloys, and weld overlays welded onto the brazing layers.

Images