Powder solder, preparation method and welding method of additive manufacturing high-temperature alloy

Abstract

The invention relates to a powder solder, a preparation method and a welding method for additive manufacturing of a high-temperature alloy, and relates to the technical field of welding material products for the high-temperature alloy, and mainly adopts the technical scheme that the chemical components of the powder solder comprise Ni, Cr, Co, W, Al, Ti, Mo, B and Hf; in the powder solder, the weight content percentage of Ni is larger than or equal to 55 wt%; the sum of the weight percentage of Cr, Co and W is 20-30 wt%; the weight content percentage of Mo is 1-4 wt%; the weight content percentage of the B is 0.5-3.5 wt%; the weight content percentage of Hf is 0.5 to 3.5 wt%; the sum of the weight percentage of Al and the weight percentage of Ti is 3-8 wt%. The powder solder is mainly used for providing the powder solder which is well matched with the additive manufacturing high-temperature alloy with the high precipitation strengthening element content, the manufacturing problem of the additive manufacturing high-temperature alloy under the condition that a large-size or complex structure is difficult to form is solved, and the powder solder has important application value.

Description

Technical Field

[0001] The present invention relates to the technical field of welding material products for high-temperature alloys and the technical field of welding of high-temperature alloys manufactured by additive manufacturing, and in particular to a powder solder and a preparation method, and a welding method for high-temperature alloys manufactured by additive manufacturing. Background Art

[0002] Additive manufacturing high temperature alloy refers to the high temperature alloy prepared by high temperature alloy powder with the help of additive manufacturing process, such as laser selective melting process or laser coaxial powder feeding process. Compared with traditional cast high temperature alloy or deformed high temperature alloy, additive manufacturing high temperature alloy has faster production cycle, less raw material consumption, finer grain structure and higher room temperature and high temperature strength. At present, it is more and more widely used in aerospace, shipbuilding, nuclear energy and other fields.

[0003] Compared with the laser coaxial powder feeding process, the high-temperature alloy printed by the laser selective melting process has better surface accuracy and higher mechanical properties. However, due to the limitations of existing technologies, although it has a high pass rate when printing parts of traditional deformed high-temperature alloy grades (such as Inconel718) with small size and simple structure, when printing high-temperature alloy parts with large size or complex structure, especially for cast high-temperature alloy grades with high precipitation strengthening element content (such as Mar-Mar247, Inconel738, etc.), it is very easy to crack due to stress accumulation during printing.

[0004] When it is necessary to manufacture alloy parts with large size or complex structure and high precipitation strengthening element content, if it is divided into smaller or simpler parts and printed separately, the printing pass rate can be greatly improved, and then the simple parts that have been manufactured are connected by vacuum brazing technology, so that large-sized or complex structure parts can be manufactured. The above manufacturing method can greatly reduce the difficulty of the additive manufacturing process of parts, greatly improve the additive manufacturing pass rate, and reduce production costs. Therefore, the development of additive manufacturing high-temperature alloy brazing connection technology will help to further expand the application scope of additive manufacturing parts and has broad development prospects.

[0005] However, due to the high content of precipitation strengthening elements (Al, Ti, Ta, etc.) in the additively manufactured high-temperature alloy composition, even if it is printed into a small-sized individual, it still has a high residual stress inside. During the subsequent brazing connection, the weld or parent material will crack due to the rapid release of stress. If soft solder is used for brazing, although the tendency of stress cracking can be alleviated to a certain extent, the lower joint strength does not match the high-strength parent material, thereby losing the advantage of high mechanical properties of additively manufactured high-temperature alloys.

[0006] Therefore, there is an urgent need to develop high-performance solders that can match additively manufactured 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 a preparation method, and a welding method for additively manufactured high-temperature alloys. The main purpose is to provide a powder solder that has good matching properties with additively manufactured high-temperature alloys with high precipitation strengthening element content.

[0008] In order to achieve the above object, the present invention mainly provides the following technical solutions:

[0009] On the one hand, an embodiment of the present invention provides 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: the weight content percentage of Ni is ≥55wt%; the sum of the weight content percentages of Cr, Co and W is 20-30wt%; the weight content percentage of Mo is 1-4wt%; the weight content percentage of B is 0.5-3.5wt%; the weight content percentage of Hf is 0.5-3.5wt%; the sum of the weight content percentages of Al and Ti is 3-8wt%.

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

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

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

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

[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 content percentage of Ni is ≥55wt%; the sum of the weight content percentages of Cr, Co, and W is 20-30wt%; the weight content percentage of Mo is 1-4wt%; the sum of the weight content percentages of Al and Ti is 3-8wt%; the weight content percentage of Ta is 4.5-7.5wt%;

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

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

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

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

[0021] On the other hand, an embodiment of the present invention provides a method for preparing the powder solder as described in any one of the above, wherein the method for preparing the powder solder comprises the following steps:

[0022] Performing gas atomization treatment on the alloy raw material to obtain alloy powder;

[0023] Performing particle screening on the alloy powder to obtain powder solder with a set particle size;

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

[0025] On the other hand, an embodiment of the present invention further provides a welding method for additively manufacturing a high-temperature alloy, wherein the welding method comprises the following steps:

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

[0027] Step 2): applying a solder paste formed by mixing powder solder and a binder to a set area of ​​the workpiece to be welded; wherein the powder solder is the powder solder according to any one of claims 1 to 5;

[0028] Step 3): applying a flow barrier to the outside of the solder paste application area to prevent the solder paste from overflowing during the soldering process;

[0029] Step 4): drying the solder paste and the flow barrier applied on the parts to be welded; preferably, the drying temperature is 70 to 120° C., and the drying time is 20 to 120 minutes;

[0030] Step 5): After the drying step, the parts to be welded are brazed to obtain the welded additively manufactured high-temperature alloy.

[0031] Preferably, in the step 1), 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; 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 of the first additively manufactured high-temperature alloy part and the second additively manufactured high-temperature alloy part need to be cleaned; preferably, the oxide film on the surface to be welded is removed by machining or grinding, and the surface to be welded is cleaned with a cleaning agent; preferably, the cleaning agent includes one or more of alcohol, acetone, gasoline, and petroleum ether; further preferably, after the cleaning treatment, step 2) needs to be completed within 24 hours; after completing step 2), step 5) needs to be performed within 24 hours to avoid oxidation of the surface to be welded; and / or

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

[0034] Preferably, in step 2), the average pile width of the solder paste applied on the set area is 0.5-3 mm, and the average pile height is 0.5-2 mm; and / or

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

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

[0037] In the step 3), the distance between the area of ​​the applied flow resist and the area of ​​the solder paste is no more than 2 mm.

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

[0039] In another aspect, an embodiment of the present invention further provides a welded additively manufactured high-temperature alloy, wherein the welded additively manufactured high-temperature alloy is welded by any of the above-mentioned additively manufactured high-temperature alloy welding methods;

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

[0041] Preferably, the tensile strength of the joint of the additively manufactured high-temperature alloy after welding is not less than 900 MPa.

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

[0043] On the one hand, an embodiment of the present invention provides 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 content percentage of Ni is ≥55wt%; the sum of the weight content percentages of Cr, Co, and W is 20-30wt%; the weight content percentage of Mo is 1-4wt%; the weight content percentage of B is 0.5-3.5wt%; the weight content percentage of Hf is 0.5-3.5wt%; the sum of the weight content percentages of Al and Ti is 3-8wt%. Wherein, the powder solder is a powder solder for additive manufacturing of high-temperature alloy welding. It should be noted here that: in order to improve the compatibility of the powder solder and the additive manufacturing high-temperature alloy (parent material) in the embodiment of the present invention, so as to ensure the overall strength and process performance of the parts, the powder solder of the present invention adds solid solution strengthening elements such as Cr, Co, W, and Mo to strengthen the weld matrix, and the total addition amount is similar to that of the parent material. The addition of Cr, Co, and W elements can expand 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 reduced plasticity and increased cracking tendency. The embodiment of the present invention controls the total amount of Cr+Co+W elements to (20-30)wt%. The appropriate amount of W and Mo elements can consume the melting elements and form a stable high-temperature phase in the early stage of the welding process, thereby avoiding the appearance of the metastable brittle phase in the later stage of welding cooling. In addition, compared with the W element, although the Mo element has a more significant effect on expanding the γ / γ′ mismatch and a better strengthening effect, it has a greater tendency to induce the formation of a topological close-packed phase (TCP phase). If the Mo addition amount is too high, it is not conducive to the service performance of the joint. Therefore, the embodiment of the present invention limits the Mo element content. The embodiment of the present invention reduces the gap between the lattice constant of the weld matrix and the matrix of the matrix alloy by adding various solid solution strengthening elements with a content similar to that in the additive manufacturing high-temperature alloy base material in the powder solder, and improves the weld strength while reducing the risk of cracking caused by stress mutation during brazing. On the basis of the above, the powder solder of the present invention uses B and Hf elements as melting point reducing elements, wherein the addition of Hf element can further reduce the melting point of the solder on the basis of purifying the grain boundary and strengthening the weld, while reducing the element diffusion rate, which can effectively reduce the excessive diffusion of B element to the base material, so as to avoid deteriorating the performance of the base material. Preferably, the powder solder of the present invention can appropriately add Si element as needed to improve fluidity and wettability, but too high Si element will also increase the brittleness of the matrix, and excessive addition of Si element may even lead to the formation of silicide, which not only reduces the joint strength, but also increases the risk of cracking, so the embodiment of the present invention limits the content of Si element. Preferably, a certain amount of Fe element will be introduced into the powder solder of the present invention, and an appropriate amount of Fe element can also play a certain role in solid solution strengthening, but too high content will also deteriorate the service performance of the weld, and the present invention limits its content.In addition, the present invention also 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 not only plays a sufficient precipitation strengthening role, but also avoids the stress cracking tendency caused by excessive γ′ content.

[0044] On the other hand, an embodiment of the present invention also provides a welding method for additively manufactured high-temperature alloys, in which the above-mentioned powder solder is used to weld the additively manufactured high-temperature alloys. Here, the above-mentioned powder solder of the present invention has a high degree of alloying, and has good element matching with the high-temperature alloy parent material. With the help of a smaller welding gap, the mutual solubility of the solder and the parent material during the welding process is further improved, the composition gap is narrowed, and stress and micro-deformation are coordinated. The originally added alloying elements and the alloying elements introduced by mutual diffusion jointly increase the mixing entropy of the system, increase the lattice distortion, and make the mismatch more negative, thereby achieving a synergistic improvement in joint strength and crack resistance.

[0045] Furthermore, in order to achieve high-performance connection of additively manufactured high-temperature alloys, the present invention heats the powder solder with the help of a suitable welding process while releasing the residual stress of the parent material, and wets and fills the surfaces to be welded between the additively manufactured high-temperature alloy parent materials with the molten solder after heating, thereby achieving metallurgical bonding between additively manufactured high-temperature alloys. Here, since additively manufactured high-temperature alloys will produce a large stress concentration during the printing process, if they are to undergo a subsequent thermal process of vacuum brazing, they are very likely to crack due to the rapid release of stress. Therefore, the present invention strictly controls the heating rate in the temperature range where the stress release effect is obvious, ensures that the internal stress is slowly released, and avoids the generation of cracks.

[0046] Furthermore, since the Hf element is introduced into the powder solder provided by the embodiment of the present invention, the cleanliness of the wetted interface of the additively manufactured high-temperature alloy parts will be higher. Based on this, the embodiment of the present invention improves the cleanliness of the wetted interface from the following aspects to ensure the welding quality, as follows:

[0047] (1) Use machining or grinding to remove the oxide film on the surface to be welded on the additively manufactured high-temperature alloy parts, and use alcohol, acetone, gasoline or petroleum ether to clean the surface to be welded. After cleaning, the powder brazing material must be applied within 24 hours, and the brazing must be carried out in the furnace within 24 hours after coating to avoid 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 brazing insulation, the vacuum pressure must not exceed 0.02 Pa to ensure the cleanliness of the atmosphere.

[0049] If brazing is performed under argon conditions, the argon dew point must be no higher than -53°C to ensure a clean atmosphere. It should be noted here that the argon dew point can be tested by a dew point meter. The dew point is related to the water content. If the dew point is higher than -53°C, the water content is high. The high atmosphere water content will affect the wetting effect, thereby reducing the welding quality.

[0050] In summary, for additively manufactured high-temperature alloys, especially when the content of precipitation strengthening elements is high, due to the preparation process and alloy composition, large internal stress will be generated during the printing process, thereby increasing the risk of cracking. It is often difficult to directly print complex structures or large-sized components without cracking, but simple structures or small-sized components can be manufactured relatively easily. With the help of the solution of the present invention, simple structures or small-sized components can be connected into complete complex structures or large-sized components through vacuum brazing, and because the powder solder used has good matching with the parent material, the obtained joint has excellent mechanical properties. Therefore, the present invention can solve the manufacturing problems of complex structures and large-sized additively manufactured high-temperature alloy components, reduce manufacturing costs, and improve manufacturing qualification rates. In summary, the present invention has huge economic value and application value.

[0051] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 This is the metallographic structure of the additively manufactured high-temperature alloy joint after welding obtained in Example 1.

[0053] Figure 2 This is the metallographic structure of the additively manufactured high-temperature alloy joint after welding obtained in Example 2.

[0054] Figure 3 This is the metallographic structure of the additively manufactured high-temperature alloy joint after welding obtained in Example 3.

[0055] Figure 4 This is a physical picture of the parts to be welded before the solder paste is applied in Example 4.

[0056] Figure 5 This is a physical picture of the parts to be welded after the solder paste and the flow barrier are applied in Example 4.

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

[0058] Figure 7 This is the metallographic structure of the additively manufactured high-temperature alloy joint after welding obtained in Example 1.

[0059] Figure 8 This is the metallographic structure of the additively manufactured high-temperature alloy joint after welding obtained in Example 2.

[0060] Fig. 9 This is the metallographic structure of the additively manufactured high-temperature alloy joint after welding obtained in Example 3.

[0061] Fig.10 This is the metallographic structure of the additively manufactured high-temperature alloy joint after welding obtained in Example 4.

[0062] Fig.11 This is the metallographic structure of the additively manufactured high-temperature alloy joint after welding obtained in Comparative Example 5.

[0063] Fig.12 This is the metallographic structure of the additively manufactured high-temperature alloy joint after welding obtained in Example 6. DETAILED DESCRIPTION

[0064] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention application are described in detail below in conjunction with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures, or characteristics in one or more embodiments may be combined in any suitable form.

[0065] On the one hand, an embodiment of the present invention provides 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 content percentage of Ni is ≥55wt%; the sum of the weight content percentages of Cr, Co, and W is 20-30wt%; the weight content percentage of Mo is 1-4wt%; the weight content percentage of B is 0.5-3.5wt%; the weight content percentage of Hf is 0.5-3.5wt%; and the sum of the weight content percentages of Al and Ti is 3-8wt%.

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

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

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

[0069] On the other hand, an embodiment of the present invention further provides 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: the melting temperature is 1400-1600°C, the powder spraying temperature is 1420-1580°C, the atomizing gas is argon, and the atomizing pressure is 4-10MPa.

[0071] Screening treatment: the alloy powder is screened to obtain a powder solder of a set particle size; preferably, the powder solder is spherical and / or nearly spherical. The particle size of the powder solder is not greater than 100 μm.

[0072] On the other hand, an embodiment of the present invention further provides a welding method for additively manufacturing a high-temperature alloy, wherein the welding method comprises 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 a part to be welded. Preferably, the welding gap of the parts to be welded (see Figure 4 As shown), the maximum value 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.

[0074] Step 2): Apply a solder paste made of a mixture of powder solder and a binder to a set area of ​​the workpiece to be welded; wherein the powder solder is any of the above-mentioned powder solders. The set area is an area on the workpiece to be welded within 3 mm of the welding gap (see Figure 4 and Figure 5 The average pile width of the solder paste applied on the set area is 0.5-3 mm, and the average pile height is 0.5-2 mm.

[0075] Preferably, the binder is an oily binder or a water-based binder (eg, Nicobraz s-binder produced by Wall Colmonoy Company); in the solder paste: the content of the binder is 7-16wt%.

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

[0077] Step 4): Drying the solder paste and flow-blocking agent coated on the parts to be welded.

[0078] Step 5): After the drying step, the parts to be welded are brazed to obtain the welded additively manufactured high-temperature alloy.

[0079] Wherein, in this step, the equipment used for the brazing treatment is a vacuum heat treatment furnace or a vacuum brazing furnace. The atmosphere of the brazing treatment is vacuum or argon. If the brazing treatment is vacuum, when the temperature is above 350°C, the vacuum pressure is not greater than 0.02Pa; if the brazing treatment is argon, the pressure of argon is 70 to 2000Pa; preferably, the dew point of argon is not higher than -53°C.

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

[0081] The present invention is further described below by specific embodiments:

[0082] Example 1

[0083] This embodiment welds additively manufactured high-temperature alloys; wherein,

[0084] The additively manufactured high-temperature alloy (parent material) is an additively manufactured high-temperature alloy part with a high content of precipitation strengthening elements (Al, Ti, Ta) prepared by a laser selective melting process, and 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 powder solder used is a spherical alloy powder with a particle size of no more than 100 μm prepared by a gas atomization process (the process parameters of the gas atomization process are set as follows: melting temperature is 1540°C, powder spraying temperature is 1520°C, atomization gas is argon, and atomization pressure is 9 MPa). The chemical composition of the powder solder is as follows (wt%): Ni-10Cr-10Co-4W-2.8Mo-2.5Al-3.5Si-1Ti-1.8B-0.5Hf.

[0086] Among them, the welding method mainly includes the following steps:

[0087] Step 1): The surfaces to be welded of the two additively manufactured high-temperature alloy specimens were processed to Ra0.4 (the oxide film was removed during the processing), and the specimens were ultrasonically cleaned with anhydrous ethanol for 5 minutes. The surfaces to be welded of the two additively manufactured high-temperature alloy specimens were aligned with a gap of 0.03mm using an energy storage spot welding machine, and then spot welded to obtain the welded parts. After spot welding, the gap was checked with a feeler gauge to confirm that the gap at any part of the surface to be welded did not exceed 0.1mm (i.e., the maximum welding gap did not exceed 0.1mm).

[0088] Step 2): Powdered solder and Nicrobraz s-binder produced by Wall Colmonoy are uniformly mixed into a paste at a weight ratio of 90wt%:10wt% to obtain solder paste. The solder paste is applied to a set area of ​​the workpiece to be welded, wherein the set area is an area on the workpiece to be welded within 2mm of the welding gap; wherein the average pile height of the applied solder paste is 0.9mm and the average pile width is 1.5mm. wherein, after the cleaning in step 1), step 2) must be completed within 24 hours.

[0089] Step 3): Nicrobraz White stop-off TYPE II stopper produced by Wall Colmonoy is applied on the outside of the solder paste. The distance between the stopper and the solder paste does not exceed 1.5 mm at the widest point, and the stopper does not cover the surface of the solder paste.

[0090] Step 4): The solder and flow-blocking agent coated parts to be welded are placed in a drying oven for drying. The drying process parameters are: drying temperature of 80° C. and drying time of 30 min.

[0091] Step 5): Put the parts to be welded that have completed the above assembly process into a furnace for brazing treatment. The furnace is a vacuum environment with a vacuum pressure not higher than 0.02Pa. The brazing process is as follows: during the heating process, the heating rate below 550°C is 3°C / min, the heating rate above 550°C is 10°C / min, the brazing treatment temperature is 1220°C, and the holding time at the brazing treatment temperature is 25 minutes. After brazing, the excess solder on the surface of the specimen is polished and polished to obtain the additively manufactured high-temperature alloy after welding. Among them, after step 2), step 5) must be completed within 24 hours.

[0092] The joint samples of the additively manufactured high-temperature alloy after welding were subjected to tensile testing, where the tensile strength of the joint was 1020MPa.

[0093] Figure 1This is the metallographic structure of the joint of the additively manufactured high-temperature alloy after welding obtained in Example 1. It can be seen that this example successfully achieves the brazing connection of the additively manufactured high-temperature alloy, the joint has no crack defects, the weld matrix is ​​a γ-Ni solid solution, and there is no low-melting point eutectic structure in the weld.

[0094] Example 2

[0095] This embodiment welds additively manufactured high-temperature alloys; wherein,

[0096] The additively manufactured high-temperature alloy (parent material) is an additively manufactured high-temperature alloy part with a high content of precipitation strengthening elements (Al, Ti, Ta) prepared by a laser selective melting process, and 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 powder solder used is a spherical alloy powder with a particle size of no more than 100 μm prepared by a gas atomization process (the process parameters of the gas atomization process are set as follows: melting temperature is 1570°C, powder spraying temperature is 1550°C, atomization gas is argon, and atomization pressure is 9 MPa). The chemical composition of the powder solder is as follows (wt%): Ni-14Cr-10Co-4W-2.9Mo-4.1Al-3.4Ti-1.25B-0.8Hf.

[0098] Among them, the welding method mainly includes the following steps:

[0099] Step 1): The surfaces to be welded of the two additively manufactured high-temperature alloy specimens were processed to Ra0.4 (the oxide film was removed during the processing), and the specimens were ultrasonically cleaned with anhydrous ethanol for 5 minutes. The surfaces to be welded of the two additively manufactured high-temperature alloy specimens were aligned with a gap of 0.09 mm using an energy storage spot welding machine, and then spot welded to obtain the welded parts. After spot welding, the gap was checked with a feeler gauge to confirm that the gap at any part of the surface to be welded did not exceed 0.1 mm (i.e., the maximum welding gap did not exceed 0.1 mm).

[0100] Step 2): Powdered solder and Nicrobraz s-binder produced by Wall Colmonoy are uniformly mixed into a paste at a weight ratio of 92wt%:8wt% to obtain solder paste. The solder paste is applied to a set area of ​​the workpiece to be welded, wherein the set area is an area on the workpiece to be welded within 1.5mm of the welding gap; wherein the average pile height of the applied solder paste is 1mm and the average pile width is 1.7mm. wherein, after the cleaning in step 1), step 2) must be completed within 24 hours.

[0101] Step 3): Nicrobraz White stop-off TYPE II stopper produced by Wall Colmonoy is applied on the outside of the solder paste. The distance between the stopper and the solder paste does not exceed 1.5 mm at the widest point, and the stopper does not cover the surface of the solder paste.

[0102] Step 4): The solder and the flow-blocking agent coated parts to be welded are placed in a drying oven for drying. The drying process parameters are: drying temperature is 100° C. and drying time is 40 minutes.

[0103] Step 5): Put the parts to be welded that have completed the above assembly process into a furnace for brazing treatment. The furnace is a vacuum environment with a vacuum pressure not higher than 0.02Pa. The brazing process is as follows: the heating rate below 550°C is 3.5°C / min, the heating rate above 550°C is 10°C / min, the brazing treatment temperature is 1230°C, and the holding time at the brazing treatment temperature is 10 minutes. After brazing, the excess solder on the surface of the specimen is polished and polished to obtain the additively manufactured high-temperature alloy after welding. Among them, after step 2), step 5) must be completed within 24 hours.

[0104] The joint samples of the additively manufactured high-temperature alloy after welding were subjected to tensile testing, where the tensile strength of the joint was 1115MPa.

[0105] Figure 2 This is the metallographic structure of the joint of the additively manufactured high-temperature alloy after welding obtained in Example 2. It can be seen that this example successfully achieves the brazing connection of the additively manufactured high-temperature alloy, the joint has no crack defects, the weld matrix is ​​a γ-Ni solid solution, and there is no low-melting point eutectic structure in the weld.

[0106] Example 3

[0107] This embodiment welds additively manufactured high-temperature alloys; wherein,

[0108] The additively manufactured high-temperature alloy (parent material) is an additively manufactured high-temperature alloy part with a high content of precipitation strengthening elements (Al, Ti, Ta) prepared by a laser selective melting process, and 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 powder solder used is a spherical alloy powder with a particle size of no more than 100 μm prepared by a gas atomization process (the process parameters of the gas atomization process are set as follows: melting temperature is 1530°C, powder spraying temperature is 1510°C, atomization gas is argon, and atomization pressure is 9 MPa). The chemical composition of the powder solder is as follows (wt%): Ni-12Cr-6Co-4W-1.2Mo-2.2Al-3.3Si-1Ti-2B-0.5Hf.

[0110] Among them, the welding method mainly includes the following steps:

[0111] Step 1): The surfaces to be welded of the two additively manufactured high-temperature alloy specimens were processed to Ra0.4 (the oxide film was removed during the processing), and the specimens were ultrasonically cleaned with anhydrous ethanol for 5 minutes. The surfaces to be welded of the two additively manufactured high-temperature alloy specimens were aligned with a gap of 0.09 mm using an energy storage spot welding machine, and then spot welded to obtain the welded parts. After spot welding, the gap was checked with a feeler gauge to confirm that the gap at any part of the surface to be welded did not exceed 0.1 mm (i.e., the maximum welding gap did not exceed 0.1 mm).

[0112] Step 2): Powdered solder and Nicrobraz s-binder produced by Wall Colmonoy are uniformly mixed into a paste at a weight ratio of 90wt%:10wt% to obtain solder paste. The solder paste is applied to a set area of ​​the workpiece to be welded, wherein the set area is an area on the workpiece to be welded within 2mm of the welding gap; wherein the average pile height of the applied solder paste is 1mm and the average pile width is 1.6mm. wherein, after the cleaning in step 1), step 2) must be completed within 24 hours.

[0113] Step 3): Nicrobraz White stop-off TYPE II stopper produced by Wall Colmonoy is applied on the outside of the solder paste. The distance between the stopper and the solder paste does not exceed 1.5 mm at the widest point, and the stopper does not cover the surface of the solder paste.

[0114] Step 4): The solder and flow-blocking agent coated parts to be welded are placed in a drying oven for drying. The drying process parameters are: drying temperature of 80° C. and drying time of 30 min.

[0115] Step 5): Put the parts to be welded that have completed the above assembly process into a furnace for brazing treatment. The furnace is a vacuum environment with a vacuum pressure not higher than 0.02Pa. The brazing process is as follows: the heating rate below 550°C is 3°C / min, the heating rate above 550°C is 10°C / min, the brazing treatment temperature is 1200°C, and the holding time at the brazing treatment temperature is 240 minutes. After brazing, the excess solder on the surface of the specimen is polished and polished to obtain the additively manufactured high-temperature alloy after welding. Among them, after step 2), step 5) must be completed within 24 hours.

[0116] The joint samples of the additively manufactured high-temperature alloy after welding were subjected to tensile testing, where the tensile strength of the joint was 1150MPa.

[0117] Figure 3 This is the metallographic structure of the joint of the additively manufactured high-temperature alloy after welding obtained in Example 3. It can be seen that this example successfully achieves the brazing connection of the additively manufactured high-temperature alloy, the joint has no crack defects, and the weld matrix is ​​a γ-Ni solid solution, fine γ′ precipitation strengthening phase is precipitated in the matrix, and there is no low-melting point eutectic structure in the weld.

[0118] Example 4

[0119] This embodiment welds additively manufactured high-temperature alloys; wherein,

[0120] The additively manufactured high-temperature alloy (parent material) is an additively manufactured high-temperature alloy part with a high content of precipitation strengthening elements (Al, Ti, Ta) prepared by a laser selective melting process, and 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 powder solder used is a spherical alloy powder with a particle size of no more than 100 μm prepared by a gas atomization process (the process parameters of the gas atomization process are set as follows: melting temperature is 1520°C, powder spraying temperature is 1500°C, atomization gas is argon, and atomization pressure is 9 MPa). The chemical composition of the powder solder is as follows (wt%): Ni-14Cr-6Co-4W-1.2Mo-2Al-1.5Si-1Ti-2.6B-1.8Hf-0.8Fe.

[0122] Among them, the welding method mainly includes the following steps:

[0123] Step 1): The surfaces to be welded of the two additively manufactured high-temperature alloy specimens were processed to Ra0.4 (the oxide film was removed during the processing), and the specimens were ultrasonically cleaned with anhydrous ethanol for 5 minutes. The surfaces to be welded of the two additively manufactured high-temperature alloy specimens were aligned with a gap of 0.04 mm by means of an energy storage spot welding machine, and spot welding was performed to obtain the welded parts (see Figure 4 After spot welding, check the gap with a feeler gauge to confirm that the gap at any part of the surface to be welded does not exceed 0.1 mm (i.e., the maximum welding gap does not exceed 0.1 mm).

[0124] Step 2): Powdered solder and Nicrobraz s-binder produced by Wall Colmonoy are uniformly mixed into a paste at a weight ratio of 87wt%:13wt% to obtain solder paste. The solder paste is applied to a set area of ​​the workpiece to be welded, wherein the set area is an area on the workpiece to be welded within 1.5mm of the welding gap; wherein the average pile height of the applied solder paste is 1.1mm and the average pile width is 1.8mm. wherein, after the cleaning in step 1), step 2) must be completed within 24 hours.

[0125] Step 3): Nicrobraz White stop-off TYPE II stopper produced by Wall Colmonoy is applied on the outside of the solder paste. The distance between the stopper and the solder paste does not exceed 1.5 mm at the widest point, and the stopper does not cover the surface of the solder paste.

[0126] Among them, solder paste and resist coating, see Figure 5 shown.

[0127] Step 4): The solder and flow-blocking agent coated parts to be welded are placed in a drying oven for drying. The drying process parameters are: drying temperature of 80° C. and drying time of 30 min.

[0128] Step 5): Put the parts to be welded that have completed the above assembly process into a furnace for brazing treatment. The furnace is slightly filled with 200Pa of argon as a protective gas, and the dew point of argon is not higher than -53°C. The brazing process is as follows: the heating rate below 550°C is 4°C / min, the heating rate above 550°C is 10°C / min, the brazing treatment temperature is 1180°C, and the insulation time at the brazing treatment temperature is 12 minutes. After brazing, the excess solder on the surface of the specimen is polished and polished to obtain the additively manufactured high-temperature alloy after welding. Among them, after step 2), step 5) must be completed within 24 hours.

[0129] The joint samples of the additively manufactured high-temperature alloy after welding were subjected to tensile testing, and the tensile strength of the joint was 945MPa.

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

[0131] Comparative Example 1

[0132] Comparative Example 1: welding of additively manufactured high-temperature alloy; wherein,

[0133] The additively manufactured high-temperature alloy (parent material) is an additively manufactured high-temperature alloy part with a high content of precipitation strengthening elements (Al, Ti, Ta) prepared by a laser selective melting process, and 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 powder solder used is a spherical alloy powder with a particle size of no more than 100 μm prepared by a gas atomization process (the process parameters of the gas atomization process are set as follows: melting temperature is 1540°C, powder spraying temperature is 1520°C, atomization gas is argon, and atomization pressure is 9 MPa). The chemical composition of the powder solder is as follows (wt%): Ni-10Cr-10Co-4W-2.8Mo-2.5Al-5.5Si-1Ti-1.6B-0.5Hf.

[0135] Among them, the welding method mainly includes the following steps:

[0136] Step 1): The surfaces to be welded of the two additively manufactured high-temperature alloy specimens were processed to Ra0.4 (the oxide film was removed during the processing), and the specimens were ultrasonically cleaned with anhydrous ethanol for 5 minutes. The surfaces to be welded of the two additively manufactured high-temperature alloy specimens were aligned with a gap of 0.02 mm using an energy storage spot welding machine, and then spot welded to obtain the welded parts. After spot welding, the gap was checked with a feeler gauge to confirm that the gap at any part of the surface to be welded did not exceed 0.1 mm (i.e., the maximum welding gap did not exceed 0.1 mm).

[0137] Step 2): Powdered solder and Nicrobraz s-binder produced by Wall Colmonoy are uniformly mixed into a paste at a weight ratio of 90wt%:10wt% to obtain solder paste. The solder paste is applied to a set area of ​​the workpiece to be welded, wherein the set area is an area on the workpiece to be welded within 2mm of the welding gap; wherein the average pile height of the applied solder paste is 0.9mm and the average pile width is 1.5mm. wherein, after the cleaning in step 1), step 2) must be completed within 24 hours.

[0138] Step 3): Nicrobraz White stop-off TYPE II stopper produced by Wall Colmonoy is applied on the outside of the solder paste. The distance between the stopper and the solder paste does not exceed 1.5 mm at the widest point, and the stopper does not cover the surface of the solder paste.

[0139] Step 4): The solder and flow-blocking agent coated parts to be welded are placed in a drying oven for drying. The drying process parameters are: drying temperature of 80° C. and drying time of 30 min.

[0140] Step 5): Put the parts to be welded that have completed the above assembly process into a furnace for brazing treatment. The furnace is a vacuum environment with a vacuum pressure not higher than 0.02Pa. The brazing process is as follows: the heating rate below 550°C is 3°C / min, the heating rate above 550°C is 10°C / min, the brazing temperature is 1220°C, and the holding time at the brazing temperature is 25 minutes. After brazing, the excess solder on the surface of the specimen is polished and polished to obtain the additively manufactured high-temperature alloy after welding. Among them, after step 2), step 5) must be completed within 24 hours.

[0141] The joint samples of the additively manufactured high-temperature alloy after welding were subjected to tensile testing, where the tensile strength of the joint was 525MPa.

[0142] Figure 7 This is the metallographic structure of the joint of the additively manufactured high-temperature alloy after welding obtained in Example 1. It can be seen that: the weld of this comparative example has discontinuously distributed microcracks locally. By counting all positions of the entire weld in sequence, the total length of the microcracks accounts for 12% of the weld. Due to the excessive Si element in the solder, the weld performance deteriorates and the weld brittleness increases. In addition, the hardness of the parent alloy is high. During the brazing process, it is difficult for the weld and the parent material to release stress through coordinated deformation, resulting in stress accumulation and microcracks in the weld, resulting in a joint strength of only 525MPa.

[0143] Comparative Example 2

[0144] Comparative Example 2: welding of additively manufactured high-temperature alloy; wherein,

[0145] The additively manufactured high-temperature alloy (parent material) is an additively manufactured high-temperature alloy part with a high content of precipitation strengthening elements (Al, Ti, Ta) prepared by a laser selective melting process, and 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 powder solder used is a spherical alloy powder with a particle size of no more than 100 μm prepared by a gas atomization process (the process parameters of the gas atomization process are set as follows: melting temperature is 1540°C, powder spraying temperature is 1520°C, atomization gas is argon, and atomization pressure is 9 MPa). The chemical composition of the powder solder is as follows (wt%): Ni-11Cr-11Co-10W-2.8Mo-2.5Al-3.5Si-1Ti-1.8B-0.5Hf.

[0147] Among them, the welding method mainly includes the following steps:

[0148] Step 1): The surfaces to be welded of the two additively manufactured high-temperature alloy specimens were processed to Ra0.4 (the oxide film was removed during the processing), and the specimens were ultrasonically cleaned with anhydrous ethanol for 5 minutes. The surfaces to be welded of the two additively manufactured high-temperature alloy specimens were aligned with a gap of 0.03mm using an energy storage spot welding machine, and then spot welded to obtain the welded parts. After spot welding, the gap was checked with a feeler gauge to confirm that the gap at any part of the surface to be welded did not exceed 0.1mm (i.e., the maximum welding gap did not exceed 0.1mm).

[0149] Step 2): Powdered solder and Nicrobraz s-binder produced by Wall Colmonoy are uniformly mixed into a paste at a weight ratio of 90wt%:10wt% to obtain solder paste. The solder paste is applied to a set area of ​​the workpiece to be welded, wherein the set area is an area on the workpiece to be welded within 2mm of the welding gap; wherein the average pile height of the applied solder paste is 0.9mm and the average pile width is 1.5mm. wherein, after the cleaning in step 1), step 2) must be completed within 24 hours.

[0150] Step 3): Nicrobraz White stop-off TYPE II stopper produced by Wall Colmonoy is applied on the outside of the solder paste. The distance between the stopper and the solder paste does not exceed 1.5 mm at the widest point, and the stopper does not cover the surface of the solder paste.

[0151] Step 4): The solder and flow-blocking agent coated parts to be welded are placed in a drying oven for drying. The drying process parameters are: drying temperature of 80° C. and drying time of 30 min.

[0152] Step 5): Put the parts to be welded that have completed the above assembly process into a furnace for brazing treatment. The furnace is a vacuum environment with a vacuum pressure not higher than 0.02Pa. The brazing process is as follows: the heating rate below 550°C is 3°C / min, the heating rate above 550°C is 10°C / min, the brazing treatment temperature is 1220°C, and the insulation time at the brazing treatment temperature is 25 minutes. After brazing, the excess solder on the surface of the specimen is polished and polished to obtain the additively manufactured high-temperature alloy after welding. Among them, after step 2), step 5) must be completed within 24 hours.

[0153] The joint samples of the additively manufactured high-temperature alloy after welding were subjected to tensile testing, where the tensile strength of the joint was 560MPa.

[0154] Figure 8 This is the metallographic structure of the joint of the additively manufactured high-temperature alloy after welding obtained in Example 2. It can be seen that intermittently distributed microcracks appear locally in the weld of this comparative example. By counting all positions of the entire weld in sequence, the total length of the microcracks accounts for 9% of the weld. Due to the excessive total addition of Cr+Co+W elements in the powder solder, the plasticity of the weld is reduced, and the larger local stress during the solidification of the solder is released in the form of local cracking, thereby reducing the joint strength and failing to reach 900MPa.

[0155] Comparative Example 3

[0156] This embodiment welds additively manufactured high-temperature alloys; wherein,

[0157] The additively manufactured high-temperature alloy (parent material) is an additively manufactured high-temperature alloy part with a high content of precipitation strengthening elements (Al, Ti, Ta) prepared by a laser selective melting process, and 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 powder solder used is a spherical alloy powder with a particle size of no more than 100 μm prepared by a gas atomization process (the process parameters of the gas atomization process are set as follows: melting temperature is 1570°C, powder spraying temperature is 1550°C, atomization gas is argon, and atomization pressure is 9 MPa). The chemical composition of the powder solder is as follows (wt%): Ni-14Cr-10Co-4W-2.9Mo-5Al-5Ti-1.25B-0.8Hf.

[0159] Among them, the welding method mainly includes the following steps:

[0160] Step 1): The surfaces to be welded of the two additively manufactured high-temperature alloy specimens were processed to Ra0.4 (the oxide film was removed during the processing), and the specimens were ultrasonically cleaned with anhydrous ethanol for 5 minutes. The surfaces to be welded of the two additively manufactured high-temperature alloy specimens were aligned with a gap of 0.09 mm using an energy storage spot welding machine, and then spot welded to obtain the welded parts. After spot welding, the gap was checked with a feeler gauge to confirm that the gap at any part of the surface to be welded did not exceed 0.1 mm (i.e., the maximum welding gap did not exceed 0.1 mm).

[0161] Step 2): Powdered solder and Nicrobraz s-binder produced by Wall Colmonoy are uniformly mixed into a paste at a weight ratio of 92wt%:8wt% to obtain solder paste. The solder paste is applied to a set area of ​​the workpiece to be welded, wherein the set area is an area on the workpiece to be welded within 2mm of the welding gap; wherein the average pile height of the applied solder paste is 1mm and the average pile width is 1.7mm. wherein, after the cleaning in step 1), step 2) must be completed within 24 hours.

[0162] Step 3): Nicrobraz White stop-off TYPE II stopper produced by Wall Colmonoy is applied on the outside of the solder paste. The distance between the stopper and the solder paste does not exceed 1.5 mm at the widest point, and the stopper does not cover the surface of the solder paste.

[0163] Step 4): The solder and the flow-blocking agent coated parts to be welded are placed in a drying oven for drying. The drying process parameters are: drying temperature is 100° C. and drying time is 40 minutes.

[0164] Step 5): Put the parts to be welded that have completed the above assembly process into a furnace for brazing treatment. The furnace is a vacuum environment with a vacuum pressure not higher than 0.02Pa. The brazing process is as follows: the heating rate below 550°C is 3.5°C / min, the heating rate above 550°C is 10°C / min, the brazing treatment temperature is 1230°C, and the holding time at the brazing treatment temperature is 10 minutes. After brazing, the excess solder on the surface of the specimen is polished and polished to obtain the additively manufactured high-temperature alloy after welding. Among them, after step 2), step 5) must be completed within 24 hours.

[0165] The joint samples of the additively manufactured high-temperature alloy after welding were subjected to tensile testing, where the tensile strength of the joint was 255MPa.

[0166] Fig. 9This is the metallographic structure of the joint of the additively manufactured high-temperature alloy after welding obtained in Example 3. It can be seen that there is a continuous crack in the center of the weld. By counting all positions of the entire weld in sequence, the total length of the cracks reaches 50% of the weld. Due to the excessive addition of Al and Ti elements in the solder, this will increase the hardness while reducing the plastic deformation ability. During the brazing process, as the solder cools and solidifies, the liquid film in some areas of the post-crystallization is torn when the residual liquid phase with high Al and Ti content is shrinked, resulting in solidification cracks, thereby greatly reducing the performance of the joint, and the tensile strength is only 255MPa.

[0167] Comparative Example 4

[0168] Comparative Example 4: welding of additively manufactured high-temperature alloy; wherein,

[0169] The additively manufactured high-temperature alloy (parent material) is an additively manufactured high-temperature alloy part with a high content of precipitation strengthening elements (Al, Ti, Ta) prepared by a laser selective melting process, and 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 powder solder used is a spherical alloy powder with a particle size of no more than 100 μm prepared by a gas atomization process (the process parameters of the gas atomization process are set as follows: melting temperature is 1530°C, powder spraying temperature is 1510°C, atomization gas is argon, and atomization pressure is 9 MPa). The chemical composition of the powder solder is as follows (wt%): Ni-12Cr-5Co-4W-1.2Mo-2.2Al-3.3Si-1Ti-2B-0.5Hf.

[0171] Among them, the welding method mainly includes the following steps:

[0172] Step 1): The surfaces to be welded of the two additively manufactured high-temperature alloy specimens were processed to Ra0.4 (the oxide film was removed during the processing), and the specimens were ultrasonically cleaned with anhydrous ethanol for 5 minutes. The surfaces to be welded of the two additively manufactured high-temperature alloy specimens were aligned with a gap of 0.09 mm using an energy storage spot welding machine, and then spot welded to obtain the welded parts. After spot welding, the gap was checked with a feeler gauge to confirm that the gap at any part of the surface to be welded did not exceed 0.1 mm (i.e., the maximum welding gap did not exceed 0.1 mm).

[0173] Step 2): Powdered solder and Nicrobraz s-binder produced by Wall Colmonoy are uniformly mixed into a paste at a weight ratio of 90wt%:10wt% to obtain solder paste. The solder paste is applied to a set area of ​​the workpiece to be welded, wherein the set area is an area on the workpiece to be welded within 2mm of the welding gap; wherein the average pile height of the applied solder paste is 1mm and the average pile width is 1.6mm. wherein, after the cleaning in step 1), step 2) must be completed within 24 hours.

[0174] Step 3): Nicrobraz White stop-off TYPE II stopper produced by Wall Colmonoy is applied on the outside of the solder paste. The distance between the stopper and the solder paste does not exceed 1.5 mm at the widest point, and the stopper does not cover the surface of the solder paste.

[0175] Step 4): The solder and flow-blocking agent coated parts to be welded are placed in a drying oven for drying. The drying process parameters are: drying temperature of 80° C. and drying time of 30 min.

[0176] Step 5): Put the parts to be welded that have completed the above assembly process into a furnace for brazing treatment. The furnace is a vacuum environment with a vacuum pressure not higher than 0.02Pa. The brazing process is as follows: the heating rate below 550°C is 6.5°C / min, the heating rate above 550°C is 10°C / min, the brazing treatment temperature is 1200°C, and the holding time at the brazing treatment temperature is 240 minutes. After brazing, the excess solder on the surface of the specimen is polished and polished to obtain the additively manufactured high-temperature alloy after welding. Among them, after step 2), step 5) must be completed within 24 hours.

[0177] The joint samples of the additively manufactured high-temperature alloy after welding were subjected to tensile testing, where the tensile strength of the joint was 735MPa.

[0178] Fig.10 This is the metallographic structure of the joint of the additively manufactured high-temperature alloy after welding obtained in Comparative Example 4. It can be seen that a large number of cracks appeared in the parent material of the joint in this comparative example. The heating rate in this comparative example was fast during the brazing process. Since the additively manufactured high-temperature alloy parent material had extremely high residual tensile stress inside, the residual internal stress of the parent material was quickly released at a faster heating rate, causing the parent material to crack, which reduced the joint performance and did not reach 900MPa.

[0179] Comparative Example 5

[0180] This embodiment welds additively manufactured high-temperature alloys; wherein,

[0181] The additively manufactured high-temperature alloy (parent material) is an additively manufactured high-temperature alloy part with a high content of precipitation strengthening elements (Al, Ti, Ta) prepared by a laser selective melting process, and 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 powder solder used is a spherical alloy powder with a particle size of no more than 100 μm prepared by a gas atomization process (the process parameters of the gas atomization process are set as follows: melting temperature is 1540°C, powder spraying temperature is 1520°C, atomization gas is argon, and atomization pressure is 9 MPa). The chemical composition of the powder solder is as follows (wt%): Ni-10Cr-10Co-4W-2.8Mo-2.5Al-3.5Si-1Ti-1.8B-0.5Hf.

[0183] Among them, the welding method mainly includes the following steps:

[0184] Step 1): The surfaces to be welded of the two additively manufactured high-temperature alloy specimens were processed to Ra0.4 (the oxide film was removed during the processing), and the specimens were ultrasonically cleaned with anhydrous ethanol for 5 minutes. The surfaces to be welded of the two additively manufactured high-temperature alloy specimens were aligned with a gap of 0.16 mm using an energy storage spot welding machine, and then spot welded to obtain the welded parts. After spot welding, the gap was checked with a feeler gauge, and the maximum welding gap was 0.18 mm.

[0185] Step 2): Powdered solder and Nicrobraz s-binder produced by Wall Colmonoy are uniformly mixed into a paste at a weight ratio of 90wt%:10wt% to obtain solder paste. The solder paste is applied to a set area of ​​the workpiece to be welded, wherein the set area is an area on the workpiece to be welded within 2mm of the welding gap; wherein the average pile height of the applied solder paste is 1.2mm and the average pile width is 1.8mm. wherein, after the cleaning in step 1), step 2) must be completed within 24h.

[0186] Step 3): Nicrobraz White stop-off TYPE II stopper produced by Wall Colmonoy is applied on the outside of the solder paste. The distance between the stopper and the solder paste does not exceed 1.5 mm at the widest point, and the stopper does not cover the surface of the solder paste.

[0187] Step 4): The solder and flow-blocking agent coated parts to be welded are placed in a drying oven for drying. The drying process parameters are: drying temperature of 80° C. and drying time of 30 min.

[0188] Step 5): Put the parts to be welded that have completed the above assembly process into a furnace for brazing treatment. The furnace is a vacuum environment with a vacuum pressure not higher than 0.02Pa. The brazing process is as follows: the heating rate below 550°C is 3°C / min, the heating rate above 550°C is 10°C / min, the brazing treatment temperature is 1220°C, and the holding time at the brazing treatment temperature is 25 minutes. After brazing, the excess solder on the surface of the specimen is polished and polished to obtain the additively manufactured high-temperature alloy after welding. Among them, after step 2), step 5) must be completed within 24 hours.

[0189] The joint samples of the additively manufactured high-temperature alloy after welding were subjected to tensile testing, and the tensile strength of the joint was 855MPa.

[0190] Fig.11 This is the metallographic structure of the joint of the additively manufactured high-temperature alloy after welding obtained in Example 5. It can be seen that although there are no crack defects in the weld of this comparative example, the weld width is wide and the tensile strength of the joint does not reach 900MPa. Since the maximum gap to be welded in this comparative example is too large, the volume of the solder in the gap increases, while the amount of the parent material dissolved during the brazing process is basically unchanged, so the proportion of the solder increases and the proportion of the parent material decreases during the mutual dissolution process, and the solder does not obtain enough strengthening elements from the dissolved parent material. As the weld area with the weakest performance in the entire joint, not only the volume of the weak area is increased due to its excessive width, but also the strength of the weld matrix is ​​not sufficiently improved due to insufficient mutual diffusion, which ultimately makes the strength of the joint less than 900MPa.

[0191] Comparative Example 6

[0192] This comparative example welds an additively manufactured high-temperature alloy; the difference between comparative example 6 and example 2 is that the powder solder in comparative example 6 does not contain the Hf element, and the rest is consistent with example 2.

[0193] The joint samples of the additively manufactured high-temperature alloy after welding in Comparative Example 6 were subjected to a tensile test, wherein the tensile strength of the joint was 875 MPa.

[0194] Fig.12 This is the metallographic structure of the additively manufactured high-temperature alloy joint after welding obtained in Comparative Example 6. It can be seen that although there are no cracks in the joint of this comparative example, a light gray mesh low-melting eutectic structure exists locally in the weld, and the tensile strength of the joint does not reach 900 MPa. Since the powder solder of this comparative example does not add the Hf element, not only can sufficient weld purification and strengthening effects not be obtained, but a low-melting eutectic structure appears in the weld, which deteriorates the performance of the joint.

[0195] It can be seen from the above embodiments 1-4 that the additively manufactured high-temperature alloys have all successfully achieved brazing connections, the joints have no crack defects, and the tensile strength of the joints is not less than 900 MPa, which shows that the vacuum brazing connection method of the present invention can achieve high-performance connection of additively manufactured high-temperature alloys.

[0196] It can be seen from the above-mentioned comparative examples 1-6 that the tensile strength of the joints is lower than 900 MPa, and the joints of comparative examples 1-4 have crack defects of varying degrees, which indicates that the solder composition exceeds the prescribed range, the heating rate exceeds the prescribed range, or the gap to be welded exceeds the prescribed range, and high-performance connection of additively manufactured high-temperature alloys cannot be successfully achieved.

[0197] Comparative Example 7

[0198] In this comparative example, the additively manufactured high-temperature alloy is welded; wherein, the difference between comparative example 7 and embodiment 4 is only that:

[0199] The dew point of argon in step 5) is -37°C.

[0200] The rest is consistent with Example 1.

[0201] The joint of the additively manufactured high-temperature alloy after welding in this comparative example was sampled and processed in order to perform a tensile test. However, the joint was broken into two sections of parent material during the machining process, and it was found that the solder only covered its original stacking area and failed to successfully wet into the gap to be welded. This is because the argon gas dew point is relatively high, and it is oxidized under the action of water vapor during the welding process, causing the solder to lose its wetting ability on the parent material, resulting in failure to weld.

[0202] Comparative Example 8

[0203] This comparative example welds the additively manufactured high-temperature alloy; wherein the difference between comparative example 8 and embodiment 1 is that:

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

[0205] Others are consistent with Example 1

[0206] The joint of the additively manufactured high-temperature alloy after welding in this comparative example was sampled for tensile testing. However, the joint broke into two sections of parent material during the machining process, and 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 was formed on the surface to be welded during the welding process, which hindered the wetting and filling of the solder on the surface to be welded of the parent material, and thus it broke directly from the weld during the machining process.

[0207] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A powder solder, characterized in that: 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 content percentage of Ni is ≥55wt%; the sum of the weight content percentages of Cr, Co and W is 20-30wt%; the weight content percentage of Mo is 1-4wt%; the weight content percentage of B is 0.5-3.5wt%; the weight content percentage of Hf is 0.5-3.5wt%; the sum of the weight content percentages of Al and Ti is 3-8wt%.

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

3. The powder solder according to claim 1 or 2, characterized in that: The powder solder is powder solder for additive manufacturing of high-temperature alloy welding; 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 content percentage of Ni is ≥55wt%; the sum of the weight content percentages of Cr, Co, and W is 20-30wt%; the weight content percentage of Mo is 1-4wt%; the sum of the weight content percentages of Al and Ti is 3-8wt%; the weight content percentage of Ta is 4.5-7.5wt%; Preferably, in the additively manufactured high-temperature alloy: the weight content percentage of Cr is 6-10wt%, the weight content percentage of Co is 6-10wt%, and the weight content percentage of W is 6-10wt%; Preferably, in the additively manufactured high-temperature alloy: the weight percentage of Al is 3-6wt%, and the weight percentage of Ti is 0-2wt%; Preferably, the chemical composition of the additively manufactured high-temperature alloy also includes grain boundary strengthening elements; preferably, the grain boundary strengthening elements include one or more of C, B, Hf, and Zr; further preferably, in the additively manufactured high-temperature alloy, C≤0.2wt%, B≤0.1w%, Hf≤2w%, and Zr≤3w%.

4. The powder solder according to any one of claims 1 to 3, characterized in that: The powder solder is spherical and / or nearly spherical; and / or The particle size of the powder solder is not greater than 100 μm.

5. The method for preparing the powder solder according to any one of claims 1 to 4, characterized in that: The method for preparing the powder solder comprises the following steps: Performing gas atomization treatment on the alloy raw material to obtain alloy powder; Performing particle screening on the alloy powder to obtain powder solder with a set particle size; Preferably, the process parameters of the gas atomization treatment are set as follows: the melting temperature is 1400-1600° C.; the powder spraying temperature is 1420-1580° C.; the atomizing gas is an inert gas, preferably argon; and the atomizing pressure is 4-10 MPa.

6. A welding method for additively manufacturing a high-temperature alloy, characterized in that: The welding method comprises the following steps: Step 1): Fixing the first additively manufactured high-temperature alloy part and the second additively manufactured high-temperature alloy part to obtain a part to be welded; Step 2): applying a solder paste formed by mixing powder solder and a binder to a set area of ​​the workpiece to be welded; wherein the powder solder is the powder solder according to any one of claims 1 to 5; Step 3): applying a flow barrier to the outside of the solder paste application area to prevent the solder paste from overflowing during the soldering process; Step 4): drying the solder paste and the flow barrier applied on the parts to be welded; preferably, the drying temperature is 70 to 120° C., and the drying time is 20 to 120 minutes; Step 5): After the drying step, the parts to be welded are brazed to obtain the welded additively manufactured high-temperature alloy.

7. The welding method for additively manufacturing high-temperature alloy according to claim 6, characterized in that: In the step 1), 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; and / or Before fixing the first additively manufactured high-temperature alloy part and the second additively manufactured high-temperature alloy part, the surfaces to be welded of the first additively manufactured high-temperature alloy part and the second additively manufactured high-temperature alloy part need to be cleaned; preferably, the oxide film on the surface to be welded is removed by machining or grinding, and the surface to be welded is cleaned with a cleaning agent; preferably, the cleaning agent includes one or more of alcohol, acetone, gasoline, and petroleum ether; further preferably, after the cleaning treatment, step 2) needs to be completed within 24 hours; after completing step 2), step 5) needs to be performed within 24 hours to avoid oxidation of the surface to be welded; and / or In the step 2), the set area is an area on the workpiece to be welded that is within 3 mm of the welding gap.

8. The welding method for additively manufacturing high-temperature alloy according to claim 6 or 7, characterized in that: In the step 2), the average pile width of the solder paste applied on the set area is 0.5-3 mm, and the average pile height is 0.5-2 mm; and / or In the step 2): the binder is an oily binder or a water-based binder; and / or In the solder paste: the content of the binder is 7-16wt%; and / or In the step 3), the distance between the area of ​​the applied flow resist and the area of ​​the solder paste is no more than 2 mm.

9. The welding method for additively manufacturing a high-temperature alloy according to any one of claims 6 to 8, characterized in that: In the step 5): The equipment used for the brazing process is a vacuum heat treatment furnace or a vacuum brazing furnace; and / or The brazing atmosphere is vacuum or argon; if the brazing atmosphere is vacuum, the vacuum pressure is not greater than 0.02 Pa when the temperature is above 350°C; if the brazing atmosphere is argon, the argon pressure is 70 to 2000 Pa; preferably, the dew point of argon is not higher than -53°C; and / or The process parameters of the brazing treatment are set as follows: the brazing treatment temperature is 1150-1230°C, and the holding time at the brazing treatment temperature is 10-240 minutes; preferably, in the process of heating to the brazing treatment temperature: when the temperature is not higher than 550°C, the heating rate does not exceed 4°C / min, and when the temperature is higher than 550°C, the heating rate does not exceed 17°C / min.

10. A welded additively manufactured high temperature alloy, characterized in that: The welded additively manufactured high-temperature alloy is welded by the additively manufactured high-temperature alloy welding method according to any one of claims 6 to 9; Preferably, the joint of the additively manufactured high-temperature alloy after welding has no crack defects, the weld matrix is ​​a γ-Ni solid solution, and there is no low-melting-point eutectic structure in the weld; Preferably, the tensile strength of the joint of the additively manufactured high-temperature alloy after welding is not less than 900 MPa.

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