A powder solder and method of making, method of welding additive manufactured high temperature alloys

Abstract

The application relates to a powder solder and a preparation method and a welding method for additive manufacturing of high-temperature alloy, and relates to the technical field of welding material products for high-temperature alloy, and mainly adopts the technical scheme that the chemical components of the powder solder include Ni, Cr, Co, W, Al, Ti, Mo, B and Hf; wherein, in the powder solder, the weight content percentage of Ni is greater than or equal to 55 wt%; the sum of the weight content percentages of Cr, Co and W is 20-30 wt%; the weight content percentage of Mo is 1-4 wt%; the weight content percentage of B is 0.5-3.5 wt%; the weight content percentage of Hf is 0.5-3.5 wt%; and the sum of the weight content percentages of Al and Ti is 3-8 wt%. The application mainly provides a powder solder which is matched with an additive manufacturing high-temperature alloy with a high content of precipitation strengthening elements, solves the manufacturing problem of the additive manufacturing high-temperature alloy in the case that a large size or a complex structure is difficult to be formed, and has important application value.

Description

Technical Field

[0001] This invention relates to the technical field of welding materials for high-temperature alloys and the technical field of welding additive manufacturing high-temperature alloys, and particularly to a powder solder and its preparation method, and a welding method for additive manufacturing high-temperature alloys. Background Technology

[0002] Additive manufacturing of high-temperature alloys refers to the production of high-temperature alloy powders using additive manufacturing processes, such as selective laser melting or coaxial laser powder feeding. Compared to traditional cast or wrought high-temperature alloys, additively manufactured high-temperature alloys offer faster production cycles, lower raw material consumption, finer grain structure, and higher room temperature and high-temperature strength, and are increasingly widely used in aerospace, shipbuilding, and nuclear energy fields.

[0003] Compared to coaxial laser powder feeding, high-temperature alloys printed using selective laser melting (SLM) have better surface precision and higher mechanical properties. However, due to limitations of current technology, although it has a high yield rate when printing small, simple traditional wrought high-temperature alloys (such as Inconel 718), it is prone to cracking during printing large or complex high-temperature alloy parts, especially for cast high-temperature alloys with high precipitation strengthening element content (such as Mar-Mar 247, Inconel 738, etc.).

[0004] When manufacturing large-sized or complex alloy parts with high precipitation-strengthening element content, breaking them down into smaller or simpler parts and printing them separately can significantly improve the printing yield. Then, vacuum brazing technology can be used to connect the simpler parts, enabling the manufacture of large-sized or complex parts. This manufacturing method greatly reduces the difficulty of additive manufacturing processes, significantly improves the yield rate, and lowers production costs. Therefore, the development of high-temperature alloy brazing joining technology in additive manufacturing will help further expand the application range of additive manufactured parts and has broad development prospects.

[0005] However, due to the high content of precipitation strengthening elements (Al, Ti, Ta, etc.) in the composition of additive manufacturing high-temperature alloys, even when printed into small-sized individuals, they still have high residual stress. During subsequent brazing, the rapid release of stress can lead to cracking of the weld or the base material. If soft solder is used for brazing, although it can alleviate the tendency of stress cracking to some extent, the lower joint strength is not matched with the high strength of the base material, thus losing the advantage of high mechanical properties of additive manufacturing high-temperature alloys.

[0006] Therefore, there is an urgent need to develop high-performance solders that can match additive manufacturing high-temperature alloys with high precipitation strengthening element content, as well as brazing processes that can slowly release stress in conjunction with the base material. Summary of the Invention

[0007] In view of this, the present invention provides a powder solder and its preparation method, and a welding method for additive manufacturing high-temperature alloys. The main purpose is to provide a powder solder that is well matched with additive manufacturing high-temperature alloys with high precipitation strengthening element content.

[0008] To achieve the above objectives, the present invention mainly provides the following technical solutions:

[0009] On one hand, embodiments of the present invention provide a powder solder, wherein the chemical composition of the powder solder includes Ni, Cr, Co, W, Al, Ti, Mo, B, and Hf; wherein,

[0010] In the powder solder: Ni has a weight percentage of ≥55wt%; the sum of the weight percentages of Cr, Co, and W is 20-30wt%; Mo has a weight percentage of 1-4wt%; B has a weight percentage of 0.5-3.5wt%; Hf has a weight percentage of 0.5-3.5wt%; and the sum of the weight percentages of Al and Ti is 3-8wt%.

[0011] Preferably, the chemical composition of the powder solder further includes silicon; wherein, in the powder solder: the weight percentage of silicon is less than or equal to 4.5 wt%; and / or

[0012] The chemical composition of the powder solder also includes Fe element; wherein, in the powder solder: the weight percentage of Fe element is less than or equal to 2 wt%; and / or

[0013] In the powder solder: the weight percentage of Cr is 7-14 wt%, the weight percentage of Co is 6-12 wt%, and the weight percentage of W is 3.5-8 wt%; and / or

[0014] In the powder solder: the weight percentage of Al is 1.5 to 6 wt%, and the weight percentage of Ti is 0 to 3 wt%.

[0015] Preferably, the powder solder is a powder solder for additive manufacturing high-temperature alloy welding;

[0016] Preferably, the chemical composition of the additive manufacturing high-temperature alloy includes Ni, Cr, Co, W, Ta, Al, Ti, and Mo; wherein, in the additive manufacturing high-temperature alloy: the weight percentage of Ni is ≥55wt%; the sum of the weight percentages of Cr, Co, and W is 20-30wt%; the weight percentage of Mo is 1-4wt%; the sum of the weight percentages of Al and Ti is 3-8wt%; and the weight percentage of Ta is 4.5-7.5wt%.

[0017] Preferably, in the additively manufactured high-temperature alloy: the weight percentage of Cr is 6-10 wt%, the weight percentage of Co is 6-10 wt%, and the weight percentage of W is 6-10 wt%.

[0018] Preferably, in the additive manufacturing high-temperature alloy: the weight percentage of Al is 3-6 wt%, and the weight percentage of Ti is 0-2 wt%.

[0019] Preferably, the chemical composition of the additively manufactured high-temperature alloy further includes grain boundary strengthening elements; preferably, the grain boundary strengthening elements include one or more of C, B, Hf, and Zr; more preferably, in the additively manufactured high-temperature alloy, C≤0.2wt%, B≤0.1wt%, Hf≤2wt%, and Zr≤3wt%.

[0020] Preferably, the powder solder is spherical and / or near-spherical; and / or the particle size of the powder solder is not greater than 100 μm.

[0021] On the other hand, embodiments of the present invention provide a method for preparing the powder solder according to any of the above claims, wherein the method for preparing the powder solder includes the following steps:

[0022] The alloy raw materials are subjected to gas atomization treatment to obtain alloy powder;

[0023] The alloy powder is subjected to particle sieving to obtain powder solder with a set particle size;

[0024] Preferably, the process parameters for the gas atomization treatment are set as follows: melting temperature is 1400-1600℃; powder spraying temperature is 1420-1580℃; the atomizing gas is an inert gas, preferably argon; and the atomization pressure is 4-10 MPa.

[0025] Furthermore, embodiments of the present invention also provide a welding method for additive manufacturing of high-temperature alloys, wherein the welding method includes the following steps:

[0026] Step 1): Fix the first additively manufactured high-temperature alloy part and the second additively manufactured high-temperature alloy part to obtain the part to be welded;

[0027] Step 2): Apply the solder paste, which is a mixture of powder solder and binder, to the designated area of ​​the workpiece to be soldered; wherein the powder solder is the powder solder according to any one of claims 1-5;

[0028] Step 3): Apply a flow-blocking agent to the outside of the area where the solder paste is applied to prevent the solder paste from flowing during the soldering process;

[0029] Step 4): Dry the solder paste and flow inhibitor applied to the workpiece to be welded; preferably, the drying temperature is 70-120°C and the drying time is 20-120 min.

[0030] Step 5): After the drying process, the workpiece is brazed to obtain the welded additive manufacturing high-temperature alloy.

[0031] Preferably, in step 1), the maximum welding gap between the parts to be welded does not exceed 0.1 mm; wherein the welding gap is the gap between the first additively manufactured high-temperature alloy part and the second additively manufactured high-temperature alloy part; and / or

[0032] Before fixing the first additively manufactured high-temperature alloy part and the second additively manufactured high-temperature alloy part, the surfaces to be welded on both parts need to be cleaned. Preferably, the oxide film on the surfaces to be welded is removed by machining or grinding, and the surfaces are cleaned with a cleaning agent. Preferably, the cleaning agent includes one or more of alcohol, acetone, gasoline, and petroleum ether. More preferably, step 2) must be completed within 24 hours after the cleaning treatment; step 5) must be performed within 24 hours after completing step 2) to avoid oxidation of the surfaces to be welded; and / or

[0033] In step 2), the set area is the area on the workpiece to be welded that is within 3 mm of the welding gap.

[0034] Preferably, in step 2): the solder paste applied to the designated area has an average width of 0.5-3 mm and an average height of 0.5-2 mm; and / or

[0035] In step 2): the adhesive is an oil-based adhesive or a water-based adhesive; and / or

[0036] In the solder paste: the binder content is 7-16 wt%; and / or

[0037] In step 3), the distance between the area where the flow-blocking agent is applied and the area where the solder paste is applied does not exceed 2 mm.

[0038] Preferably, in step 5): the equipment used for the brazing process is a vacuum heat treatment furnace or a vacuum brazing furnace; and / or the atmosphere for the brazing process is vacuum or argon; if the atmosphere for the brazing process is vacuum, then when the temperature is above 350°C, the vacuum pressure is not greater than 0.02 Pa; if the atmosphere for the brazing process is argon, then the argon pressure is 70–2000 Pa; preferably, the dew point of argon is not higher than -53°C; and / or the process parameters for the brazing process are set as follows: the brazing temperature is 1150–1230°C, and the holding time at the brazing temperature is 10–240 minutes; preferably, during the process of heating to the brazing temperature: when the temperature is not higher than 550°C, the heating rate is not more than 4°C / min, and when the temperature is higher than 550°C, the heating rate is not more than 17°C / min.

[0039] In another aspect, embodiments of the present invention also provide a welded additive manufacturing high-temperature alloy, wherein the welded additive manufacturing high-temperature alloy is welded by the welding method of any of the above-mentioned additive manufacturing high-temperature alloys;

[0040] Preferably, the joint of the additively manufactured high-temperature alloy after welding is free of cracks and defects, the weld matrix is ​​γ-Ni solid solution, and there is no low-melting-point eutectic structure in the weld.

[0041] Preferably, the tensile strength of the welded additive manufacturing high-temperature alloy joint is not less than 900 MPa.

[0042] Compared with the prior art, the powder solder and its preparation method, and the welding method for additive manufacturing of high-temperature alloys of the present invention have at least the following beneficial effects:

[0043] On one hand, embodiments of the present invention provide a powder solder, wherein the chemical composition of the powder solder includes Ni, Cr, Co, W, Al, Ti, Mo, B, and Hf; wherein, in the powder solder: the weight percentage of Ni is ≥55wt%; the sum of the weight percentages of Cr, Co, and W is 20-30wt%; the weight percentage of Mo is 1-4wt%; the weight percentage of B is 0.5-3.5wt%; the weight percentage of Hf is 0.5-3.5wt%; and the sum of the weight percentages of Al and Ti is 3-8wt%. The powder solder is a powder solder for welding high-temperature alloys in additive manufacturing. It should be noted that, in order to improve the compatibility between the powder solder and the high-temperature alloy (base material) in additive manufacturing, and to ensure the overall strength and process performance of the parts, solid solution strengthening elements such as Cr, Co, W, and Mo are added to the powder solder of the present invention to strengthen the weld matrix, and the total amount added is similar to that of the base material. The addition of Cr, Co, and W elements can increase the γ / γ′ mismatch, reduce the stacking fault energy of the matrix, and improve the matrix strength. However, if the content is too high, it will lead to a decrease in plasticity and an increase in the tendency to crack. In this embodiment of the invention, the total amount of Cr+Co+W elements is controlled at (20-30) wt%. Appropriate amounts of W and Mo elements can consume melting point depletion elements and form stable high-temperature phases in the early stage of the welding process, thereby avoiding the appearance of metastable brittle phases in the later stage of welding cooling. In addition, compared with W, although Mo has a more significant effect on increasing the γ / γ′ mismatch and a better strengthening effect, it also has a greater tendency to induce the formation of topologically close-packed phases (TCP phases). If the amount of Mo added is too high, it will be detrimental to the service performance of the joint. Therefore, this embodiment of the invention limits the content of Mo elements. This embodiment of the invention adds solid solution strengthening elements with a content similar to that in the additive manufacturing high-temperature alloy base material to the powder solder, thereby reducing the difference in lattice constant between the weld matrix and the base alloy matrix, reducing the risk of cracking caused by stress abrupt changes during brazing, and improving the weld strength. Based on the above, the powder solder of the present invention uses boron (B) and hydroxyl radical (Hf) as melting point reducing elements. The addition of Hf can further lower the melting point of the solder while purifying grain boundaries and strengthening the weld, and simultaneously reduce the element diffusion rate, effectively reducing excessive diffusion of boron into the base material to avoid deteriorating the base material's properties. Preferably, the powder solder of the present invention can appropriately add silicon (Si) to improve fluidity and wettability. However, excessive Si can increase matrix brittleness, and excessive Si addition can even lead to the formation of silicides, not only reducing joint strength but also increasing the risk of cracking. Therefore, the Si content is limited in the embodiments of the present invention. Preferably, a certain amount of iron (Fe) is introduced into the powder solder of the present invention. Appropriate amounts of Fe can also play a certain role in solid solution strengthening, but excessive content can also deteriorate the weld's service performance. Therefore, its content is limited in the present invention.In addition, the present invention adds precipitation strengthening element Al to the powder solder, and optionally adds precipitation strengthening element Ti. By controlling the total amount of Al+Ti elements, an appropriate amount of γ′ precipitation strengthening phase is obtained, which can play a sufficient precipitation strengthening role while avoiding stress cracking tendency caused by excessive γ′ content.

[0044] On the other hand, embodiments of the present invention also provide a welding method for additive manufacturing of high-temperature alloys, wherein the aforementioned powder solder is used to weld the additively manufactured high-temperature alloys. Here, the powder solder of the present invention has a high degree of alloying, good elemental compatibility with the high-temperature alloy base material, and, with the help of a smaller welding gap, further enhances the mutual solubility between the solder and the base material during welding, reduces compositional differences, coordinates stress and micro-deformation, and the original added alloying elements and the alloying elements introduced through interdiffusion together increase the mixing entropy of the system, increase lattice distortion, and make the mismatch more negative, thus achieving a synergistic improvement in joint strength and crack resistance.

[0045] Furthermore, to achieve high-performance bonding of additively manufactured high-temperature alloys, this invention utilizes a suitable welding process to heat the powder solder while simultaneously releasing residual stress in the base material. The molten solder then wets and fills the surfaces to be welded between the additively manufactured high-temperature alloy base materials, thereby achieving a metallurgical bond between them. Here, because the additively manufactured high-temperature alloy generates significant stress concentration during the printing process, subsequent vacuum brazing can easily lead to cracking due to rapid stress release. Therefore, this invention strictly controls the heating rate in the temperature range where stress release is significant, ensuring slow stress release and preventing crack formation.

[0046] Furthermore, the powder solder provided in this embodiment of the invention introduces Hf element, which places higher demands on the cleanliness of the wetting interface for additively manufactured high-temperature alloy parts. Based on this, this embodiment of the invention improves the cleanliness of the wetting interface in the following ways to ensure welding quality, as detailed below:

[0047] (1) Remove the oxide film on the surface to be welded on the additive manufacturing high temperature alloy parts by machining or grinding, and clean the surface to be welded with alcohol, acetone, gasoline or petroleum ether. After cleaning, the powder brazing filler metal should be applied within 24 hours. The surface to be brazed should be placed in the furnace within 24 hours after the coating to prevent secondary oxidation of the surface to be welded.

[0048] (2) If brazing is performed under vacuum conditions, the vacuum pressure must meet the following requirements: from 350°C to the end of the brazing heat preservation, the vacuum pressure must not exceed 0.02Pa to ensure the cleanliness of the atmosphere.

[0049] If brazing is performed under argon atmosphere, the argon dew point must not exceed -53°C to ensure a clean atmosphere. It should be noted that the argon dew point can be measured using a dew point meter. The dew point is related to the moisture content; if the dew point is above -53°C, the moisture content is high. High atmospheric moisture content will affect the wetting effect, thus reducing the welding quality.

[0050] In summary, for additive manufacturing of high-temperature alloys, especially when the content of precipitation strengthening elements is high, significant internal stress is generated during the printing process due to the preparation process and alloy composition, increasing the risk of cracking. It is often difficult to directly print complex structures or large-sized components without cracking, but it is relatively easy to manufacture simple structures or small-sized components. The solution of this invention allows simple structures or small-sized components to be joined into complete complex structures or large-sized components via vacuum brazing. Furthermore, due to the good compatibility between the powder solder and the base material, the resulting joint exhibits excellent mechanical properties. Therefore, this invention can solve the manufacturing challenges of complex structures and large-sized additively manufactured high-temperature alloy components, reduce manufacturing costs, and improve the manufacturing yield. In conclusion, this invention has significant economic and application value.

[0051] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0052] Figure 1 This is the metallographic structure of the welded additive manufacturing high-temperature alloy joint obtained in Example 1.

[0053] Figure 2 This is the metallographic structure of the welded additive manufacturing high-temperature alloy joint obtained in Example 2.

[0054] Figure 3 This is the metallographic structure of the welded additive manufacturing high-temperature alloy joint obtained in Example 3.

[0055] Figure 4 This is a photograph of the workpiece to be soldered before the solder paste is applied in Example 4.

[0056] Figure 5 This is a photograph of the workpiece to be soldered after the solder paste and flow barrier agent have been applied in Example 4.

[0057] Figure 6 This is a photograph of the joint of the additively manufactured high-temperature alloy obtained in Example 4 after welding.

[0058] Figure 7 This is the metallographic structure of the welded additive manufacturing high-temperature alloy joint obtained in Comparative Example 1.

[0059] Figure 8 This is the metallographic structure of the welded additive manufacturing high-temperature alloy joint obtained in Comparative Example 2.

[0060] Figure 9 This is the metallographic structure of the welded additive manufacturing high-temperature alloy joint obtained in Comparative Example 3.

[0061] Figure 10 This is the metallographic structure of the welded additive manufacturing high-temperature alloy joint obtained in Comparative Example 4.

[0062] Figure 11 The metallographic structure of the welded additive manufacturing high-temperature alloy joint obtained in Comparative Example 5.

[0063] Figure 12 This is the metallographic structure of the welded additive manufacturing high-temperature alloy joint obtained in Comparative Example 6. Detailed Implementation

[0064] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the specific embodiments, structures, features, and effects according to the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments. In the following description, different "an embodiment" or "an embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0065] On one hand, embodiments of the present invention provide a powder solder, wherein the chemical composition of the powder solder includes Ni, Cr, Co, W, Al, Ti, Mo, B, and Hf; wherein, in the powder solder: the weight percentage of Ni is ≥55wt%; the sum of the weight percentages of Cr, Co, and W is 20-30wt%; the weight percentage of Mo is 1-4wt%; the weight percentage of B is 0.5-3.5wt%; the weight percentage of Hf is 0.5-3.5wt%; and the sum of the weight percentages of Al and Ti is 3-8wt%.

[0066] Preferably, the chemical composition of the powder solder further includes silicon (Si); wherein, in the powder solder, the weight percentage of Si is less than or equal to 4.5 wt%. Preferably, the chemical composition of the powder solder further includes iron (Fe); wherein, in the powder solder, the weight percentage of Fe is less than or equal to 2 wt%.

[0067] Preferably, in the powder solder: the weight percentage of Cr is 7-14 wt%, the weight percentage of Co is 6-12 wt%, and the weight percentage of W is 3.5-8 wt%.

[0068] Preferably, in the powder solder: the weight percentage of Al is 1.5 to 6 wt%, and the weight percentage of Ti is 0 to 3 wt%.

[0069] Furthermore, embodiments of the present invention also provide a method for preparing the above-mentioned powder solder, comprising the following steps:

[0070] Atomization treatment: The alloy raw material is subjected to gas atomization treatment to obtain alloy powder; preferably, the process parameters of the gas atomization treatment are set as follows: melting temperature is 1400~1600℃, powder spraying temperature is 1420~1580℃, atomizing gas is argon, and atomization pressure is 4~10MPa.

[0071] Sieving process: The alloy powder is subjected to particle sieving to obtain powder solder with a set particle size; preferably, the powder solder is spherical and / or near-spherical. The particle size of the powder solder is not greater than 100 μm.

[0072] Furthermore, embodiments of the present invention also provide a welding method for additive manufacturing of high-temperature alloys, wherein the welding method includes the following steps:

[0073] Step 1): Fix the first additively manufactured high-temperature alloy part and the second additively manufactured high-temperature alloy part to obtain the part to be welded. Preferably, the welding gap of the part to be welded (see...) Figure 4 (As shown) The maximum value shall not exceed 0.1 mm; wherein, the welding gap is the gap between the first additively manufactured high-temperature alloy part and the second additively manufactured high-temperature alloy part.

[0074] Step 2): Apply the solder paste, a mixture of powdered solder and binder, to the designated area of ​​the workpiece to be soldered; wherein the powdered solder is any of the powdered solders described above. The designated area is the region on the workpiece to be soldered within 3 mm of the solder gap (see [reference]). Figure 4 and Figure 5 (As shown). The solder paste applied to the designated area has an average width of 0.5-3 mm and an average height of 0.5-2 mm.

[0075] Preferably, the binder is an oil-based binder or a water-based binder (e.g., Nicrobraz s-binder binder manufactured by Wall Colmonoy); the binder content in the solder paste is 7-16 wt%.

[0076] Step 3): Apply a flow-blocking agent to the outside of the solder paste application area to prevent the solder paste from flowing during soldering (see...). Figure 5 (As shown). The distance between the flow inhibitor and the solder must not exceed 2mm, and the flow inhibitor must not cover the surface of the solder.

[0077] Step 4): Dry the solder paste and flow barrier applied to the workpiece to be welded.

[0078] Step 5): After the drying process, the workpiece is brazed to obtain the welded additive manufacturing high-temperature alloy.

[0079] In this step, the brazing process is performed using a vacuum heat treatment furnace or a vacuum brazing furnace. The atmosphere for the brazing process is vacuum or argon. If the brazing process is performed in vacuum, the vacuum pressure is no greater than 0.02 Pa when the temperature is above 350°C; if the brazing process is performed in argon, the argon pressure is 70–2000 Pa; preferably, the dew point of argon is no higher than -53°C.

[0080] The process parameters for the brazing process are set as follows: the brazing temperature is 1150-1230℃, and the brazing holding time is 10-240 minutes; preferably, during the process of heating to the brazing temperature: when the temperature is not higher than 550℃, the heating rate is not more than 4℃ / min, and when the temperature is higher than 550℃, the heating rate is not more than 17℃ / min, so as to avoid excessive heating power, thereby affecting the life of the power supply and the heating element.

[0081] The present invention will be further illustrated below with specific embodiments:

[0082] Example 1

[0083] This embodiment demonstrates the welding of additively manufactured high-temperature alloys; wherein...

[0084] The additive manufacturing high-temperature alloy (base material) is an additive manufacturing high-temperature alloy part with high precipitation strengthening element (Al, Ti, Ta) content prepared by laser selective melting process. Its chemical composition is as follows (wt%): Ni-8Cr-8Co-7.85W-6.03Ta-5.5Al-0.68Ti-2.03Mo-0.08C-0.014B.

[0085] The selected powder solder is a spherical alloy powder with a particle size of no more than 100 μm, prepared by a gas atomization process (the process parameters for gas atomization are as follows: melting temperature 1540℃, powder spraying temperature 1520℃, atomizing gas argon, and atomization pressure 9 MPa). The chemical composition of this powder solder is as follows (wt%): Ni-10Cr-10Co-4W-2.8Mo-2.5Al-3.5Si-1Ti-1.8B-0.5Hf.

[0086] The welding method mainly includes the following steps:

[0087] Step 1): Machin the welding surfaces of the two additively manufactured high-temperature alloy specimens to Ra0.4 (removing the oxide film during machining). Ultrasonically clean the specimens with anhydrous ethanol for 5 minutes. Using a storage-energy spot welding machine, align the welding surfaces of the two additively manufactured high-temperature alloy specimens, leaving a 0.03mm gap, and then spot weld to obtain the weldable parts. After spot welding, use a feeler gauge to recheck the gap, confirming that the gap at any point on the welding surface does not exceed 0.1mm (i.e., the maximum welding gap does not exceed 0.1mm).

[0088] Step 2): Mix the powdered solder with Nicorobraz s-binder adhesive (manufactured by Wall Colmonoy) at a weight ratio of 90 wt%: 10 wt% to form a paste, thus obtaining solder paste. Apply the solder paste to the designated area on the workpiece to be soldered, where the designated area is the area on the workpiece within 2 mm of the solder gap; the average height of the applied solder paste is 0.9 mm, and the average width is 1.5 mm. Step 2) must be completed within 24 hours after the cleaning in Step 1).

[0089] Step 3): Apply Nicrobraz White stop-off TYPE II resist agent manufactured by Wall Colmonoy to the outside of the solder paste. The distance between the resist agent and the solder paste should not exceed 1.5 mm at the widest point, and the resist agent should not cover the surface of the solder paste.

[0090] Step 4): Place the workpieces coated with solder and flow inhibitor into a drying oven for drying. The drying process parameters are: drying temperature 80℃ and drying time 30min.

[0091] Step 5): Place the assembled parts into a furnace for brazing. The furnace is a vacuum environment with a pressure not exceeding 0.02 Pa. The brazing process is as follows: during the heating process, the heating rate is 3℃ / min below 550℃ and 10℃ / min above 550℃. The brazing temperature is 1220℃, and the holding time at the brazing temperature is 25 minutes. After brazing, grind and polish the surface of the part to remove excess solder, obtaining the welded additive manufacturing high-temperature alloy. Step 5) must be completed within 24 hours after step 2).

[0092] Tensile tests were conducted on samples of the welded additive manufacturing high-temperature alloy joints, and the tensile strength of the joints was 1020 MPa.

[0093] Figure 1The image shows the metallographic structure of the welded additive manufacturing high-temperature alloy joint obtained in Example 1. It can be seen that this example successfully achieved the brazing connection of the additive manufacturing high-temperature alloy. The joint has no crack defects, and the weld matrix is ​​γ-Ni solid solution with no low-melting-point eutectic structure in the weld.

[0094] Example 2

[0095] This embodiment demonstrates the welding of additively manufactured high-temperature alloys; wherein...

[0096] The additive manufacturing high-temperature alloy (base material) is an additive manufacturing high-temperature alloy part with high precipitation strengthening element (Al, Ti, Ta) content prepared by laser selective melting process. Its chemical composition is as follows (wt%): Ni-9Cr-8.5Co-7.7W-5.5Ta-5.7Al-1Ti-2.2Mo-0.05C-0.015B-0.5Hf.

[0097] The selected powder solder is a spherical alloy powder with a particle size of no more than 100 μm, prepared by a gas atomization process (the process parameters for gas atomization are as follows: melting temperature 1570℃, powder spraying temperature 1550℃, atomizing gas argon, and atomization pressure 9 MPa). The chemical composition of this powder solder is as follows (wt%): Ni-14Cr-10Co-4W-2.9Mo-4.1Al-3.4Ti-1.25B-0.8Hf.

[0098] The welding method mainly includes the following steps:

[0099] Step 1): Machin the welding surfaces of the two additively manufactured high-temperature alloy specimens to Ra0.4 (removing the oxide film during machining). Ultrasonically clean the specimens with anhydrous ethanol for 5 minutes. Using a storage-energy spot welding machine, align the welding surfaces of the two additively manufactured high-temperature alloy specimens, leaving a 0.09mm gap, and then spot weld to obtain the weldable parts. After spot welding, use a feeler gauge to recheck the gap, confirming that the gap at any point on the welding surface does not exceed 0.1mm (i.e., the maximum welding gap does not exceed 0.1mm).

[0100] Step 2): Mix the powdered solder with Nicorobraz s-binder adhesive (manufactured by Wall Colmonoy) at a weight ratio of 92 wt% to 8 wt% to form a paste, thus obtaining solder paste. Apply the solder paste to the designated area on the workpiece to be soldered, wherein the designated area is the area on the workpiece within 1.5 mm of the solder gap; the average height of the applied solder paste is 1 mm and the average width is 1.7 mm. Step 2) must be completed within 24 hours after the cleaning in Step 1).

[0101] Step 3): Apply Nicrobraz White stop-off TYPE II resist agent manufactured by Wall Colmonoy to the outside of the solder paste. The distance between the resist agent and the solder paste should not exceed 1.5 mm at the widest point, and the resist agent should not cover the surface of the solder paste.

[0102] Step 4): Place the workpieces coated with solder and flow inhibitor into a drying oven for drying. The drying process parameters are: drying temperature 100℃ and drying time 40min.

[0103] Step 5): Place the assembled parts into a furnace for brazing. The furnace is a vacuum environment with a vacuum pressure not exceeding 0.02 Pa. The brazing process is as follows: the heating rate is 3.5℃ / min below 550℃, and the heating rate is 10℃ / min above 550℃. The brazing temperature is 1230℃, and the holding time at the brazing temperature is 10 minutes. After brazing, grind and polish the surface of the part to remove excess solder, obtaining the welded additive manufacturing high-temperature alloy. Step 5 must be completed within 24 hours after step 2).

[0104] Tensile tests were performed on samples of the welded additive manufacturing high-temperature alloy joints, and the tensile strength of the joints was 1115 MPa.

[0105] Figure 2 The image shows the metallographic structure of the welded additive manufacturing high-temperature alloy joint obtained in Example 2. It can be seen that this example successfully achieved the brazing connection of the additive manufacturing high-temperature alloy. The joint has no crack defects, the weld matrix is ​​γ-Ni solid solution, and there is no low-melting-point eutectic structure in the weld.

[0106] Example 3

[0107] This embodiment demonstrates the welding of additively manufactured high-temperature alloys; wherein...

[0108] The additive manufacturing high-temperature alloy (base material) is an additive manufacturing high-temperature alloy part with high precipitation strengthening element (Al, Ti, Ta) content prepared by laser selective melting process. Its chemical composition is as follows (wt%): Ni-8Cr-8Co-7.85W-6.03Ta-5.5Al-0.68Ti-2.03Mo-0.08C-0.014B.

[0109] The selected powder solder is a spherical alloy powder with a particle size of no more than 100 μm, prepared by a gas atomization process (the process parameters for gas atomization are as follows: melting temperature 1530℃, powder spraying temperature 1510℃, atomizing gas argon, and atomization pressure 9 MPa). The chemical composition of this powder solder is as follows (wt%): Ni-12Cr-6Co-4W-1.2Mo-2.2Al-3.3Si-1Ti-2B-0.5Hf.

[0110] The welding method mainly includes the following steps:

[0111] Step 1): Machin the welding surfaces of the two additively manufactured high-temperature alloy specimens to Ra0.4 (removing the oxide film during machining). Ultrasonically clean the specimens with anhydrous ethanol for 5 minutes. Using a storage-energy spot welding machine, align the welding surfaces of the two additively manufactured high-temperature alloy specimens, leaving a 0.09mm gap, and then spot weld to obtain the weldable parts. After spot welding, use a feeler gauge to recheck the gap, confirming that the gap at any point on the welding surface does not exceed 0.1mm (i.e., the maximum welding gap does not exceed 0.1mm).

[0112] Step 2): Mix the powdered solder with Nicorobraz s-binder adhesive (manufactured by Wall Colmonoy) at a weight ratio of 90 wt%: 10 wt% to form a paste, thus obtaining solder paste. Apply the solder paste to the designated area on the workpiece to be soldered, where the designated area is the area on the workpiece within 2 mm of the solder gap; the average height of the applied solder paste is 1 mm, and the average width is 1.6 mm. Step 2) must be completed within 24 hours after the cleaning in Step 1).

[0113] Step 3): Apply Nicrobraz White stop-off TYPE II resist agent manufactured by Wall Colmonoy to the outside of the solder paste. The distance between the resist agent and the solder paste should not exceed 1.5 mm at the widest point, and the resist agent should not cover the surface of the solder paste.

[0114] Step 4): Place the workpieces coated with solder and flow inhibitor into a drying oven for drying. The drying process parameters are: drying temperature 80℃ and drying time 30min.

[0115] Step 5): Place the assembled parts into a furnace for brazing. The furnace should be in a vacuum environment with a pressure not exceeding 0.02 Pa. The brazing process is as follows: the heating rate is 3℃ / min below 550℃ and 10℃ / min above 550℃. The brazing temperature is 1200℃, and the holding time at the brazing temperature is 240 minutes. After brazing, grind and polish the surface of the part to remove excess solder, obtaining the welded additive manufacturing high-temperature alloy. Step 5 must be completed within 24 hours after step 2).

[0116] Tensile tests were performed on samples of the welded additive manufacturing high-temperature alloy joints, and the tensile strength of the joints was 1150 MPa.

[0117] Figure 3 The image shows the metallographic structure of the welded additive manufacturing high-temperature alloy joint obtained in Example 3. It can be seen that this example successfully achieved the brazing connection of the additive manufacturing high-temperature alloy. The joint has no crack defects, and the weld matrix is ​​a γ-Ni solid solution with fine γ′ precipitate strengthening phases precipitated in the matrix. There is no low-melting-point eutectic structure in the weld.

[0118] Example 4

[0119] This embodiment demonstrates the welding of additively manufactured high-temperature alloys; wherein...

[0120] The additive manufacturing high-temperature alloy (base material) is an additive manufacturing high-temperature alloy part with high precipitation strengthening element (Al, Ti, Ta) content prepared by laser selective melting process. Its chemical composition is as follows (wt%): Ni-7Cr-7Co-7W-5Ta-5.3Al-0.8Ti-2.4Mo-0.07C-0.01B-0.8Hf-0.2Zr.

[0121] The selected powder solder is a spherical alloy powder with a particle size of no more than 100 μm, prepared by a gas atomization process (the process parameters for gas atomization are as follows: melting temperature 1520℃, powder spraying temperature 1500℃, atomizing gas argon, and atomization pressure 9 MPa). The chemical composition of this powder solder is as follows (wt%): Ni-14Cr-6Co-4W-1.2Mo-2Al-1.5Si-1Ti-2.6B-1.8Hf-0.8Fe.

[0122] The welding method mainly includes the following steps:

[0123] Step 1): Machin the welding surfaces of the two additively manufactured high-temperature alloy specimens to Ra0.4 (removing the oxide film during machining). Ultrasonically clean the specimens with anhydrous ethanol for 5 minutes. Using a storage-energy spot welding machine, align the welding surfaces of the two additively manufactured high-temperature alloy specimens, leaving a 0.04mm gap, and then spot weld to position them, obtaining the parts to be welded (see...). Figure 4 (As shown). After spot welding, the gap is checked again with a feeler gauge to confirm that the gap at any part of the surface to be welded does not exceed 0.1mm (that is, the maximum welding gap does not exceed 0.1mm).

[0124] Step 2): Mix the powdered solder with Nicorobraz s-binder adhesive (manufactured by Wall Colmonoy) at a weight ratio of 87 wt% to 13 wt% to form a paste, thus obtaining solder paste. Apply the solder paste to the designated area on the workpiece to be soldered, wherein the designated area is the area on the workpiece within 1.5 mm of the solder gap; the average height of the applied solder paste is 1.1 mm and the average width is 1.8 mm. Step 2) must be completed within 24 hours after the cleaning in Step 1).

[0125] Step 3): Apply Nicrobraz White stop-off TYPE II resist agent manufactured by Wall Colmonoy to the outside of the solder paste. The distance between the resist agent and the solder paste should not exceed 1.5 mm at the widest point, and the resist agent should not cover the surface of the solder paste.

[0126] For details on solder paste and anti-flow agent application, please refer to [link / reference]. Figure 5 As shown.

[0127] Step 4): Place the workpieces coated with solder and flow inhibitor into a drying oven for drying. The drying process parameters are: drying temperature 80℃ and drying time 30min.

[0128] Step 5): Place the assembled parts into a furnace for brazing. The furnace is slightly padded with argon gas at 200 Pa as a protective gas, and the dew point of the argon gas should not exceed -53℃. The brazing process is as follows: the heating rate is 4℃ / min below 550℃, and the heating rate is 10℃ / min above 550℃. The brazing temperature is 1180℃, and the holding time at the brazing temperature is 12 minutes. After brazing, grind and polish the surface of the part to remove excess solder, obtaining the welded additive manufacturing high-temperature alloy. Step 5) must be completed within 24 hours after step 2).

[0129] Tensile tests were performed on samples of the welded additive manufacturing high-temperature alloy joints, and the tensile strength of the joints was 945 MPa.

[0130] Figure 6 This is a physical image of the joint of the additively manufactured high-temperature alloy obtained in Example 4 after welding. It can be seen that this example successfully achieved the brazing connection of the additively manufactured high-temperature alloy. The joint has no crack defects, and the weld matrix is ​​γ-Ni solid solution with fine γ′ precipitate strengthening phase precipitated in the matrix. There is no low-melting-point eutectic structure in the weld.

[0131] Comparative Example 1

[0132] Comparative Example 1 involves welding additively manufactured high-temperature alloys; among which,

[0133] The additive manufacturing high-temperature alloy (base material) is an additive manufacturing high-temperature alloy part with high precipitation strengthening element (Al, Ti, Ta) content prepared by laser selective melting process. Its chemical composition is as follows (wt%): Ni-8Cr-8Co-7.85W-6.03Ta-5.5Al-0.68Ti-2.03Mo-0.08C-0.014B.

[0134] The selected powder solder is a spherical alloy powder with a particle size of no more than 100 μm, prepared by a gas atomization process (the process parameters for gas atomization are as follows: melting temperature 1540℃, powder spraying temperature 1520℃, atomizing gas argon, and atomization pressure 9 MPa). The chemical composition of this powder solder is as follows (wt%): Ni-10Cr-10Co-4W-2.8Mo-2.5Al-5.5Si-1Ti-1.6B-0.5Hf.

[0135] The welding method mainly includes the following steps:

[0136] Step 1): Machin the welding surfaces of the two additively manufactured high-temperature alloy specimens to Ra0.4 (removing the oxide film during machining). Ultrasonically clean the specimens with anhydrous ethanol for 5 minutes. Using a storage-energy spot welding machine, align the welding surfaces of the two additively manufactured high-temperature alloy specimens, leaving a 0.02mm gap, and then spot weld to obtain the weldable parts. After spot welding, use a feeler gauge to recheck the gap, confirming that the gap at any point on the welding surface does not exceed 0.1mm (i.e., the maximum welding gap does not exceed 0.1mm).

[0137] Step 2): Mix the powdered solder with Nicorobraz s-binder adhesive (manufactured by Wall Colmonoy) at a weight ratio of 90 wt%: 10 wt% to form a paste, thus obtaining solder paste. Apply the solder paste to the designated area on the workpiece to be soldered, where the designated area is the area on the workpiece within 2 mm of the solder gap; the average height of the applied solder paste is 0.9 mm, and the average width is 1.5 mm. Step 2) must be completed within 24 hours after the cleaning in Step 1).

[0138] Step 3): Apply Nicrobraz White stop-off TYPE II resist agent manufactured by Wall Colmonoy to the outside of the solder paste. The distance between the resist agent and the solder paste should not exceed 1.5 mm at the widest point, and the resist agent should not cover the surface of the solder paste.

[0139] Step 4): Place the workpieces coated with solder and flow inhibitor into a drying oven for drying. The drying process parameters are: drying temperature 80℃ and drying time 30min.

[0140] Step 5): Place the assembled parts into a furnace for brazing. The furnace should be in a vacuum environment with a pressure not exceeding 0.02 Pa. The brazing process is as follows: the heating rate is 3℃ / min below 550℃ and 10℃ / min above 550℃. The brazing temperature is 1220℃, and the holding time at the brazing temperature is 25 minutes. After brazing, grind and polish the surface of the part to remove excess solder, obtaining the welded additive manufacturing high-temperature alloy. Step 5 must be completed within 24 hours after step 2).

[0141] Tensile tests were performed on samples of the welded additive manufacturing high-temperature alloy joints, and the tensile strength of the joints was 525 MPa.

[0142] Figure 7 The metallographic structure of the additively manufactured high-temperature alloy joint obtained in Comparative Example 1 shows that intermittent microcracks appear in the weld of this comparative example. A statistical analysis of all locations along the entire weld reveals that the total length of microcracks accounts for 12% of the weld. Excessive Si in the solder degrades the weld performance and increases its brittleness. Furthermore, the high hardness of the base alloy makes it difficult for the weld and base alloy to release stress through coordinated deformation during brazing, leading to stress accumulation and the appearance of microcracks in the weld. This results in a joint strength of only 525 MPa.

[0143] Comparative Example 2

[0144] Comparative Example 2 involves welding additively manufactured high-temperature alloys; among which,

[0145] The additive manufacturing high-temperature alloy (base material) is an additive manufacturing high-temperature alloy part with high precipitation strengthening element (Al, Ti, Ta) content prepared by laser selective melting process. Its chemical composition is as follows (wt%): Ni-8Cr-8Co-7.85W-6.03Ta-5.5Al-0.68Ti-2.03Mo-0.08C-0.014B.

[0146] The selected powder solder is a spherical alloy powder with a particle size of no more than 100 μm, prepared by a gas atomization process (the process parameters for gas atomization are as follows: melting temperature 1540℃, powder spraying temperature 1520℃, atomizing gas argon, and atomization pressure 9 MPa). The chemical composition of this powder solder is as follows (wt%): Ni-11Cr-11Co-10W-2.8Mo-2.5Al-3.5Si-1Ti-1.8B-0.5Hf.

[0147] The welding method mainly includes the following steps:

[0148] Step 1): Machin the welding surfaces of the two additively manufactured high-temperature alloy specimens to Ra0.4 (removing the oxide film during machining). Ultrasonically clean the specimens with anhydrous ethanol for 5 minutes. Using a storage-energy spot welding machine, align the welding surfaces of the two additively manufactured high-temperature alloy specimens, leaving a 0.03mm gap, and then spot weld to obtain the weldable parts. After spot welding, use a feeler gauge to recheck the gap, confirming that the gap at any point on the welding surface does not exceed 0.1mm (i.e., the maximum welding gap does not exceed 0.1mm).

[0149] Step 2): Mix the powdered solder with Nicorobraz s-binder adhesive (manufactured by Wall Colmonoy) at a weight ratio of 90 wt%: 10 wt% to form a paste, thus obtaining solder paste. Apply the solder paste to the designated area on the workpiece to be soldered, where the designated area is the area on the workpiece within 2 mm of the solder gap; the average height of the applied solder paste is 0.9 mm, and the average width is 1.5 mm. Step 2) must be completed within 24 hours after the cleaning in Step 1).

[0150] Step 3): Apply Nicrobraz White stop-off TYPE II resist agent manufactured by Wall Colmonoy to the outside of the solder paste. The distance between the resist agent and the solder paste should not exceed 1.5 mm at the widest point, and the resist agent should not cover the surface of the solder paste.

[0151] Step 4): Place the workpieces coated with solder and flow inhibitor into a drying oven for drying. The drying process parameters are: drying temperature 80℃ and drying time 30min.

[0152] Step 5): Place the assembled parts into a furnace for brazing. The furnace should be in a vacuum environment with a pressure not exceeding 0.02 Pa. The brazing process is as follows: the heating rate is 3℃ / min below 550℃ and 10℃ / min above 550℃. The brazing temperature is 1220℃, and the holding time at the brazing temperature is 25 minutes. After brazing, grind and polish the surface of the part to remove excess solder, obtaining the welded additive manufacturing high-temperature alloy. Step 5 must be completed within 24 hours after step 2).

[0153] Tensile tests were performed on samples of the welded additive manufacturing high-temperature alloy joints, and the tensile strength of the joints was 560 MPa.

[0154] Figure 8 The metallographic structure of the additively manufactured high-temperature alloy joint obtained in Comparative Example 2 after welding is shown. It can be seen that discontinuous microcracks appear in the weld of this comparative example. A statistical analysis of all locations along the entire weld revealed that the total length of microcracks accounts for 9% of the weld length. Due to the excessive total addition of Cr+Co+W elements in the powder solder, the weld plasticity is reduced. During solder solidification, the large local stress is released through localized cracking, thus reducing the joint strength to below 900 MPa.

[0155] Comparative Example 3

[0156] This embodiment demonstrates the welding of additively manufactured high-temperature alloys; wherein...

[0157] The additive manufacturing high-temperature alloy (base material) is an additive manufacturing high-temperature alloy part with high precipitation strengthening element (Al, Ti, Ta) content prepared by laser selective melting process. Its chemical composition is as follows (wt%): Ni-9Cr-8.5Co-7.7W-5.5Ta-5.7Al-1Ti-2.2Mo-0.05C-0.015B-0.5Hf.

[0158] The selected powder solder is a spherical alloy powder with a particle size of no more than 100 μm, prepared by a gas atomization process (the process parameters for gas atomization are as follows: melting temperature 1570℃, powder spraying temperature 1550℃, atomizing gas argon, and atomization pressure 9 MPa). The chemical composition of this powder solder is as follows (wt%): Ni-14Cr-10Co-4W-2.9Mo-5Al-5Ti-1.25B-0.8Hf.

[0159] The welding method mainly includes the following steps:

[0160] Step 1): Machin the welding surfaces of the two additively manufactured high-temperature alloy specimens to Ra0.4 (removing the oxide film during machining). Ultrasonically clean the specimens with anhydrous ethanol for 5 minutes. Using a storage-energy spot welding machine, align the welding surfaces of the two additively manufactured high-temperature alloy specimens, leaving a 0.09mm gap, and then spot weld to obtain the weldable parts. After spot welding, use a feeler gauge to recheck the gap, confirming that the gap at any point on the welding surface does not exceed 0.1mm (i.e., the maximum welding gap does not exceed 0.1mm).

[0161] Step 2): Mix the powdered solder with Nicorobraz s-binder adhesive (manufactured by Wall Colmonoy) at a weight ratio of 92 wt% to 8 wt% to form a paste, thus obtaining solder paste. Apply the solder paste to the designated area on the workpiece to be soldered, where the designated area is the area on the workpiece within 2 mm of the solder gap; the average height of the applied solder paste is 1 mm, and the average width is 1.7 mm. Step 2) must be completed within 24 hours after the cleaning in Step 1).

[0162] Step 3): Apply Nicrobraz White stop-off TYPE II resist agent manufactured by Wall Colmonoy to the outside of the solder paste. The distance between the resist agent and the solder paste should not exceed 1.5 mm at the widest point, and the resist agent should not cover the surface of the solder paste.

[0163] Step 4): Place the workpieces coated with solder and flow inhibitor into a drying oven for drying. The drying process parameters are: drying temperature 100℃ and drying time 40min.

[0164] Step 5): Place the assembled parts into a furnace for brazing. The furnace should be in a vacuum environment with a pressure not exceeding 0.02 Pa. The brazing process is as follows: the heating rate is 3.5℃ / min below 550℃, and 10℃ / min above 550℃. The brazing temperature is 1230℃, and the holding time at that temperature is 10 minutes. After brazing, grind and polish the surface of the part to remove excess solder, obtaining the welded additive manufacturing high-temperature alloy. Step 5 must be completed within 24 hours after step 2).

[0165] Tensile tests were performed on samples of the welded additive manufacturing high-temperature alloy joints, and the tensile strength of the joints was 255 MPa.

[0166] Figure 9The metallographic structure of the additively manufactured high-temperature alloy joint obtained in Example 3 after welding shows a continuous crack in the center of the weld. A statistical analysis of all locations along the entire weld revealed that the total crack length reached 50% of the weld length. Excessive addition of Al and Ti elements in the solder leads to increased hardness but decreased plastic deformation capacity. During brazing, as the solder cools and solidifies, the post-crystallized areas are fed by the residual liquid phase with high Al and Ti content, causing the liquid film to tear and resulting in solidification cracks. This significantly reduces the joint performance, with a tensile strength of only 255 MPa.

[0167] Comparative Example 4

[0168] Comparative Example 4 involved welding additively manufactured high-temperature alloys; among which,

[0169] The additive manufacturing high-temperature alloy (base material) is an additive manufacturing high-temperature alloy part with high precipitation strengthening element (Al, Ti, Ta) content prepared by laser selective melting process. Its chemical composition is as follows (wt%): Ni-8Cr-8Co-7.85W-6.03Ta-5.5Al-0.68Ti-2.03Mo-0.08C-0.014B.

[0170] The selected powder solder is a spherical alloy powder with a particle size of no more than 100 μm, prepared by a gas atomization process (the process parameters for gas atomization are as follows: melting temperature 1530℃, powder spraying temperature 1510℃, atomizing gas argon, and atomization pressure 9 MPa). The chemical composition of this powder solder is as follows (wt%): Ni-12Cr-5Co-4W-1.2Mo-2.2Al-3.3Si-1Ti-2B-0.5Hf.

[0171] The welding method mainly includes the following steps:

[0172] Step 1): Machin the welding surfaces of the two additively manufactured high-temperature alloy specimens to Ra0.4 (removing the oxide film during machining). Ultrasonically clean the specimens with anhydrous ethanol for 5 minutes. Using a storage-energy spot welding machine, align the welding surfaces of the two additively manufactured high-temperature alloy specimens, leaving a 0.09mm gap, and then spot weld to obtain the weldable parts. After spot welding, use a feeler gauge to recheck the gap, confirming that the gap at any point on the welding surface does not exceed 0.1mm (i.e., the maximum welding gap does not exceed 0.1mm).

[0173] Step 2): Mix the powdered solder with Nicorobraz s-binder adhesive (manufactured by Wall Colmonoy) at a weight ratio of 90 wt%: 10 wt% to form a paste, thus obtaining solder paste. Apply the solder paste to the designated area on the workpiece to be soldered, where the designated area is the area on the workpiece within 2 mm of the solder gap; the average height of the applied solder paste is 1 mm, and the average width is 1.6 mm. Step 2) must be completed within 24 hours after the cleaning in Step 1).

[0174] Step 3): Apply Nicrobraz White stop-off TYPE II resist agent manufactured by Wall Colmonoy to the outside of the solder paste. The distance between the resist agent and the solder paste should not exceed 1.5 mm at the widest point, and the resist agent should not cover the surface of the solder paste.

[0175] Step 4): Place the workpieces coated with solder and flow inhibitor into a drying oven for drying. The drying process parameters are: drying temperature 80℃ and drying time 30min.

[0176] Step 5): Place the assembled parts into a furnace for brazing. The furnace is a vacuum environment with a pressure not exceeding 0.02 Pa. The brazing process is as follows: the heating rate is 6.5℃ / min below 550℃, and the heating rate is 10℃ / min above 550℃. The brazing temperature is 1200℃, and the holding time at the brazing temperature is 240 minutes. After brazing, grind and polish the surface of the part to remove excess solder, obtaining the welded additive manufacturing high-temperature alloy. Step 5) must be completed within 24 hours after step 2).

[0177] Tensile tests were performed on samples of the welded additive manufacturing high-temperature alloy joints, and the tensile strength of the joints was 735 MPa.

[0178] Figure 10 The image shows the metallographic structure of the welded additive-manufactured high-temperature alloy joint obtained in Comparative Example 4. It can be seen that numerous cracks appeared in the base material portion of the joint in this comparative example. During the brazing process in this comparative example, the heating rate was rapid. Due to the extremely high residual tensile stress within the additive-manufactured high-temperature alloy base material, the rapid release of this residual internal stress at the high heating rate caused cracking in the base material, reducing the joint performance and preventing it from reaching 900 MPa.

[0179] Comparative Example 5

[0180] This embodiment demonstrates the welding of additively manufactured high-temperature alloys; wherein...

[0181] The additive manufacturing high-temperature alloy (base material) is an additive manufacturing high-temperature alloy part with high precipitation strengthening element (Al, Ti, Ta) content prepared by laser selective melting process. Its chemical composition is as follows (wt%): Ni-8Cr-8Co-7.85W-6.03Ta-5.5Al-0.68Ti-2.03Mo-0.08C-0.014B.

[0182] The selected powder solder is a spherical alloy powder with a particle size of no more than 100 μm, prepared by a gas atomization process (the process parameters for gas atomization are as follows: melting temperature 1540℃, powder spraying temperature 1520℃, atomizing gas argon, and atomization pressure 9 MPa). The chemical composition of this powder solder is as follows (wt%): Ni-10Cr-10Co-4W-2.8Mo-2.5Al-3.5Si-1Ti-1.8B-0.5Hf.

[0183] The welding method mainly includes the following steps:

[0184] Step 1): Machin the welding surfaces of the two additively manufactured high-temperature alloy specimens to Ra0.4 (removing the oxide film during machining). Ultrasonically clean the specimens with anhydrous ethanol for 5 minutes. Using a storage-energy spot welding machine, align the welding surfaces of the two specimens, leaving a 0.16mm gap, and then spot weld to position them, obtaining the parts to be welded. After spot welding, verify the gap using a feeler gauge; the maximum weld gap is 0.18mm.

[0185] Step 2): Mix the powdered solder with Nicorobraz s-binder adhesive (manufactured by Wall Colmonoy) at a weight ratio of 90 wt%: 10 wt% to form a paste, thus obtaining solder paste. Apply the solder paste to the designated area on the workpiece to be soldered, where the designated area is the area on the workpiece within 2 mm of the solder gap; the average height of the applied solder paste is 1.2 mm, and the average width is 1.8 mm. Step 2) must be completed within 24 hours after the cleaning in Step 1).

[0186] Step 3): Apply Nicrobraz White stop-off TYPE II resist agent manufactured by Wall Colmonoy to the outside of the solder paste. The distance between the resist agent and the solder paste should not exceed 1.5 mm at the widest point, and the resist agent should not cover the surface of the solder paste.

[0187] Step 4): Place the workpieces coated with solder and flow inhibitor into a drying oven for drying. The drying process parameters are: drying temperature 80℃ and drying time 30min.

[0188] Step 5): Place the assembled parts into a furnace for brazing. The furnace should be in a vacuum environment with a pressure not exceeding 0.02 Pa. The brazing process is as follows: the heating rate is 3℃ / min below 550℃ and 10℃ / min above 550℃. The brazing temperature is 1220℃, and the holding time at that temperature is 25 minutes. After brazing, grind and polish the surface of the part to remove excess solder, obtaining the welded additive manufacturing high-temperature alloy. Step 5 must be completed within 24 hours after step 2).

[0189] Tensile tests were performed on samples of the welded additive manufacturing high-temperature alloy joints, and the tensile strength of the joints was 855 MPa.

[0190] Figure 11 The metallographic structure of the additively manufactured high-temperature alloy joint obtained in Comparative Example 5 is shown. It can be seen that although there are no cracks in the weld of this comparative example, the weld width is relatively wide, and the tensile strength of the joint does not reach 900 MPa. Because the maximum gap to be welded in this comparative example is too large, the volume of the solder in the gap increases. Since the amount of base metal dissolved during brazing remains essentially constant, the proportion of solder increases and the proportion of base metal decreases during mutual dissolution. The solder does not obtain sufficient strengthening elements from the dissolved base metal. As the weakest area in the entire joint, the weld not only has an excessively wide width, thus increasing the volume of the weak zone, but also suffers from insufficient interdiffusion, resulting in insufficient improvement in the strength of the weld matrix, ultimately leading to a joint strength of less than 900 MPa.

[0191] Comparative Example 6

[0192] This comparative example demonstrates the welding of additively manufactured high-temperature alloys; the difference between Comparative Example 6 and Example 2 is that the powder brazing filler metal in Comparative Example 6 does not contain Hf element, while the rest is the same as Example 2.

[0193] Tensile tests were performed on samples of the additive manufacturing high-temperature alloy joint after welding in Comparative Example 6. The tensile strength of the joint was 875 MPa.

[0194] Figure 12 The metallographic structure of the additively manufactured high-temperature alloy joint obtained in Comparative Example 6 is shown. It can be seen that although there are no cracks in this comparative example joint, a light gray, network-like low-melting-point eutectic structure exists locally in the weld, and the tensile strength of the joint does not reach 900 MPa. Because the powder solder in this comparative example did not contain Hf, it not only failed to achieve sufficient weld purification and strengthening effects, but also exhibited a low-melting-point eutectic structure in the weld, deteriorating the joint's performance.

[0195] As can be seen from Examples 1-4 above, the additive manufacturing high-temperature alloys have all been successfully brazed, with no cracks or defects in the joints and a tensile strength of not less than 900 MPa. This shows that the vacuum brazing connection method of the present invention can achieve high-performance connection of additive manufacturing high-temperature alloys.

[0196] As can be seen from the above Comparative Examples 1-6, the tensile strength of the joints is less than 900 MPa, and the joints of Comparative Examples 1-4 have crack defects of varying degrees. This indicates that if the solder composition exceeds the specified range, the heating rate exceeds the specified range, or the gap to be welded exceeds the specified range, it is impossible to successfully achieve high-performance connection of additive manufacturing high-temperature alloys.

[0197] Comparative Example 7

[0198] This comparative example demonstrates the welding of additively manufactured high-temperature alloys; the only difference between Comparative Example 7 and Example 4 is that:

[0199] In step 5), the dew point of argon gas is -37°C.

[0200] Everything else is the same as in Example 1.

[0201] The joint of the additive manufacturing high-temperature alloy after welding was sampled and processed for tensile testing. However, during the machining process, the joint broke into two pieces of the base material. It was found that the solder only covered its original stacking area and failed to successfully wet the gap to be welded. This was because the argon dew point was high and the solder oxidized under the action of water vapor during the welding process, causing the solder to lose its ability to wet the base material, thus resulting in failure to weld.

[0202] Comparative Example 8

[0203] This comparative example demonstrates the welding of additively manufactured high-temperature alloys; the difference between Comparative Example 8 and Example 1 is as follows:

[0204] In step 5), the vacuum pressure fluctuates between 0.06 Pa and 0.1 Pa.

[0205] Everything else is the same as in Example 1.

[0206] Samples were taken from the joint of the additively manufactured high-temperature alloy after welding in this comparative example for tensile testing. However, during machining, the joint broke into two pieces of base material. It was found that the solder failed to fill the entire gap to be welded. This was because the vacuum pressure was too high, and an oxide film formed on the surface to be welded during the welding process, which hindered the solder from wetting and filling the gap on the base material surface to be welded. Therefore, it would break directly from the weld during machining.

[0207] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A welding method for additive manufacturing of high-temperature alloys, characterized in that, The welding method includes the following steps: Step 1): Fix the first additively manufactured high-temperature alloy part and the second additively manufactured high-temperature alloy part to obtain the part to be welded; Step 2): Apply the solder paste, which is a mixture of powdered solder and binder, to the designated area of ​​the workpiece to be soldered; Step 3): Apply a flow-blocking agent to the outside of the area where the solder paste is applied to prevent the solder paste from flowing during the soldering process; Step 4): Dry the solder paste and flow barrier agent applied to the workpiece to be welded; Step 5): After the drying process, the workpiece is brazed to obtain the welded additive manufacturing high-temperature alloy. The chemical composition of the powder solder includes Ni, Cr, Co, W, Al, Ti, Mo, B, and Hf; wherein, In the powder solder: Ni has a weight percentage ≥ 55 wt%; the sum of the weight percentages of Cr, Co, and W is 20-30 wt%; Mo has a weight percentage of 1-4 wt%; B has a weight percentage of 0.5-3.5 wt%; Hf has a weight percentage of 0.5-3.5 wt%; and the sum of the weight percentages of Al and Ti is 3-8 wt%. Wherein, the maximum welding gap of the parts to be welded does not exceed 0.1 mm; wherein, the welding gap is the gap between the first additively manufactured high-temperature alloy part and the second additively manufactured high-temperature alloy part; The process parameters for the brazing process are set as follows: the brazing temperature is 1150-1230℃, and the holding time at the brazing temperature is 10-240 minutes; wherein, during the process of heating to the brazing temperature: when the temperature is not higher than 550℃, the heating rate is not more than 4℃ / min, and when the temperature is higher than 550℃, the heating rate is not more than 17℃ / min.

2. The welding method for additive manufacturing of high-temperature alloys according to claim 1, characterized in that, The chemical composition of the powder solder also includes silicon (Si); wherein, in the powder solder: the weight percentage of Si is less than or equal to 4.5 wt%; and / or The chemical composition of the powder solder also includes Fe element; wherein, in the powder solder: the weight percentage of Fe element is less than or equal to 2 wt%; and / or In the powder solder: the weight percentage of Cr is 7-14 wt%, the weight percentage of Co is 6-12 wt%, and the weight percentage of W is 3.5-8 wt%; and / or In the powder solder: the weight percentage of Al is 1.5~6wt%, and the weight percentage of Ti is 0~3wt%.

3. The welding method for additive manufacturing of high-temperature alloys according to claim 1, characterized in that, The powder solder is a powder solder for welding additive manufacturing high-temperature alloys; wherein the chemical composition of the additive manufacturing high-temperature alloy includes Ni, Cr, Co, W, Ta, Al, Ti, and Mo; wherein in the additive manufacturing high-temperature alloy: the weight percentage of Ni is ≥55wt%; the sum of the weight percentages of Cr, Co, and W is 20~30wt%; the weight percentage of Mo is 1~4wt%; the sum of the weight percentages of Al and Ti is 3~8wt%; and the weight percentage of Ta is 4.5~7.5wt%.

4. The welding method for additive manufacturing of high-temperature alloys according to claim 3, characterized in that, In the additive manufacturing high-temperature alloy: the weight percentage of Cr is 6~10wt%, the weight percentage of Co is 6~10wt%, and the weight percentage of W is 6~10wt%.

5. The welding method for additive manufacturing of high-temperature alloys according to claim 3, characterized in that, In the additive manufacturing high-temperature alloy: the weight percentage of Al is 3~6wt%, and the weight percentage of Ti is 0~2wt%.

6. The welding method for additive manufacturing of high-temperature alloys according to claim 3, characterized in that, The chemical composition of the additively manufactured high-temperature alloy also includes grain boundary strengthening elements.

7. The welding method for additive manufacturing of high-temperature alloys according to claim 6, characterized in that, The grain boundary strengthening element includes one or more of C, B, Hf, and Zr; wherein, in the additive manufacturing high-temperature alloy, C≤0.2wt%, B≤0.1wt%, Hf≤2wt%, and Zr≤3wt%.

8. The welding method for additive manufacturing of high-temperature alloys according to claim 1, characterized in that, The powder solder is spherical and / or near-spherical; and / or The particle size of the powder solder is no greater than 100 μm.

9. The welding method for additive manufacturing of high-temperature alloys according to claim 1, characterized in that, The method for preparing the powder solder includes the following steps: The alloy raw materials are subjected to gas atomization treatment to obtain alloy powder; The alloy powder is subjected to particle sieving to obtain powder solder with a set particle size.

10. The welding method for additive manufacturing of high-temperature alloys according to claim 9, characterized in that, The process parameters for the gas atomization treatment are set as follows: melting temperature is 1400~1600℃; powder spraying temperature is 1420~1580℃; atomizing gas is inert gas; atomization pressure is 4~10MPa.

11. The welding method for additive manufacturing of high-temperature alloys according to claim 1, characterized in that, The welding method includes the following steps: In step 4), the drying temperature is 70~120℃ and the drying time is 20~120min.

12. The welding method for additive manufacturing of high-temperature alloys according to claim 1, characterized in that, Before fixing the first additively manufactured high-temperature alloy part and the second additively manufactured high-temperature alloy part, the surfaces of the first additively manufactured high-temperature alloy part and the second additively manufactured high-temperature alloy part to be welded need to be cleaned.

13. The welding method for additive manufacturing of high-temperature alloys according to claim 12, characterized in that, Remove the oxide film from the surface to be welded by machining or grinding, and clean the surface with a cleaning agent.

14. The welding method for additive manufacturing of high-temperature alloys according to claim 13, characterized in that, The cleaning agent includes one or more of alcohol, acetone, gasoline, and petroleum ether.

15. The welding method for additive manufacturing of high-temperature alloys according to claim 12, characterized in that, After the cleaning process, step 2 must be completed within 24 hours; after completing step 2), step 5 must be performed within 24 hours to avoid oxidation of the surface to be welded.

16. The welding method for additive manufacturing of high-temperature alloys according to claim 1, characterized in that, In step 2), the set area is the area on the workpiece to be welded that is within 3 mm of the welding gap.

17. The welding method for additive manufacturing of high-temperature alloys according to claim 1, characterized in that, In step 2), the solder paste applied to the designated area has an average width of 0.5-3 mm and an average height of 0.5-2 mm. and / or In step 2): the adhesive is an oil-based adhesive or a water-based adhesive; and / or In the solder paste: the binder content is 7-16 wt%; and / or In step 3), the distance between the area where the flow-blocking agent is applied and the area where the solder paste is applied does not exceed 2 mm.

18. The welding method for additive manufacturing of high-temperature alloys according to claim 1, characterized in that, In step 5): The equipment used for the brazing process is a vacuum heat treatment furnace or a vacuum brazing furnace.

19. The welding method for additive manufacturing of high-temperature alloys according to claim 1, characterized in that, In step 5): The brazing atmosphere is a vacuum or argon; if the brazing atmosphere is a vacuum, the vacuum pressure is no greater than 0.02 Pa when the temperature is above 350°C; if the brazing atmosphere is argon, the argon pressure is 70~2000 Pa; wherein the dew point of argon is no higher than -53°C.

20. A welded additive manufacturing high-temperature alloy, characterized in that, The welded additive manufacturing high-temperature alloy is welded by the welding method of the additive manufacturing high-temperature alloy according to any one of claims 1-19.

21. The additive manufacturing high-temperature alloy after welding according to claim 20, characterized in that, The welded additive manufacturing high-temperature alloy has no crack defects at the joint, the weld matrix is ​​γ-Ni solid solution, and there is no low-melting-point eutectic structure in the weld.

22. The additive manufacturing high-temperature alloy after welding according to claim 20, characterized in that, The tensile strength of the welded additive manufacturing high-temperature alloy joint is not less than 900 MPa.

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