A method for remelting of powder superalloy coarse powder return

Abstract

The application provides a method for remelting powder superalloy coarse powder return material, and relates to the technical field of nickel-based superalloy refining. The method for remelting powder superalloy coarse powder return material comprises the process steps of coarse powder return material forming, alloy powder ingot smelting, alloy powder ingot refining, alloy powder ingot strengthening refining and coarse powder return material ingot pouring. The binder is at least one of pectin, dextrin, fructose, amylopectin and potato starch. The application realizes the aggregation and dissolution of small-particle oxide inclusions by reasonable binder and coarse powder return material ratio, alloy powder ingot and alloy new material ingot ratio, twice refining process selection, high-temperature melt treatment and strong electromagnetic stirring, so that the size and quantity of inclusions are reduced; then, [O], [N] and [H] are deeply removed by improving the vacuum degree and prolonging the refining time, and the content of [H] is the lowest and can reach zero point several ppm.

Description

Technical Field

[0001] This invention relates to the technical field of nickel-based superalloy refining, and more particularly to a method for remelting recycled powder superalloy coarse powder. Background Technology

[0002] With the rapid development of my country's aerospace industry, the demand for powder metallurgy superalloys, a key material for manufacturing core components of powder turbine disks, is constantly increasing. However, the yield of powder with a particle size smaller than 60μm, prepared by argon atomization, is less than 70%. Furthermore, due to the increased content of oxygen, nitrogen, and other gases and non-metallic inclusions in the recycled coarse powder compared to virgin material, over 30% of the coarse powder is unusable, resulting in significant resource waste and high costs for powder turbine disks. This research aims to develop a technology for the remelting and reuse of coarse high-temperature alloy powder, which will significantly reduce the cost of powder metallurgy superalloys and enhance the competitiveness and resource utilization efficiency of my country's powder metallurgy superalloy turbine disks.

[0003] In addition, because vacuum induction melting furnaces operate in a vacuum environment, directly using powder as raw material for melting presents challenges such as severe powder adsorption and difficulty in heat conduction and transfer. Therefore, powder shaping before melting is a crucial step. For example, Chinese patent CN101440436A discloses a purification smelting process for high-temperature alloy return materials. The return materials are not the coarse powder (over 30%) found in high-temperature alloy powders prepared by argon atomization. Although the smelting method is vacuum melting, if coarse powder is being used, problems such as severe powder adsorption and difficulty in heat conduction and transfer will arise.

[0004] However, the blanks obtained by traditional pressing and forming have low strength and weak adhesion between particles, making them very easy to break during operation, resulting in secondary pulverization and subsequent powder absorption in the vacuum. Therefore, it is particularly important to develop a new, high-strength powder forming method to provide high-quality raw materials for the subsequent purification and melting of high-temperature alloys containing coarse powder return materials.

[0005] Chinese patent CN114318022A discloses a smelting process for nickel-based high-temperature alloys, but there are very few patents concerning powder forming.

[0006] For example, Chinese patent CN113652564A discloses a method for smelting high-temperature alloys using recycled materials. This method involves the selection of raw materials, including high-temperature alloy ingots fixed to electrodes, recycled materials in a recycled material feeder, and alloy slag in a crystallizer. Obviously, the alloy slag has a complex composition, the slag temperature is not high enough to melt the recycled materials, and inclusions are difficult to remove effectively. Moreover, the smelting time is long, the energy consumption is high, the operation process is complicated, the operation is difficult, and the range of high-temperature alloy compositions to be prepared is not the same.

[0007] Chinese patent CN111621675A discloses a method for smelting K452 high-temperature alloy containing recycled material. This method requires chemical composition analysis of the recycled material and, through surface pretreatment, reveals that the recycled material is not coarse powder. Therefore, it cannot solve the technical problems of severe vacuum powder adsorption and poor thermal conductivity and transfer in the smelting of high-temperature alloys from coarse powder. CN115948657A discloses a purification and recycling method for high-temperature alloy recycled material. This method is similar to the aforementioned method, but it does not target coarse powder recycled material and also faces the same technical challenges.

[0008] Chinese patent CN111534713A discloses a purification treatment method for recycled high-temperature alloy castings and a high-temperature alloy. It requires adding a covering slag to the surface of the molten steel during the high-temperature refining process for slag removal. Not only does it not target coarse powder recycled materials, but the method for removing inclusions is to select a covering slag with specific components for treatment and electromagnetic stirring. The method of adding slag is also not simple, all of which increase production costs. Summary of the Invention

[0009] The technical problem to be solved by this invention is that there are very few technologies for reusing coarse powder with a current efficiency of over 30%, and the existing technologies for reusing coarse powder have technical difficulties such as difficulty in forming powder before smelting, serious vacuum powder suction, difficulty in powder heat conduction and transfer, difficulty in removing oxide inclusions and deep removal of [O] and [N]. In addition, the existing technologies for reusing large amounts of waste such as gating channels and risers generated during casting and processing all require pretreatment of the waste before smelting. This obviously gives the technical inspiration of first forming blanks from coarse powder return materials and then smelting them. Therefore, the aforementioned technical problems are difficult to solve.

[0010] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0011] A method for remelting recycled powder superalloy coarse powder, the method being as follows:

[0012] S1. Coarse powder return material forming

[0013] The binder and coarse powder return material are mixed, then water is added and stirred to make it into dough-like coarse powder. The dough-like coarse powder return material is then shaped and dried to obtain alloy powder ingots.

[0014] S2, Alloy powder ingot smelting

[0015] The new alloy ingot and the S1 alloy powder ingot are placed together in a vacuum induction melting furnace for melting to obtain the alloy powder ingot melt;

[0016] S3, Alloy Powder Refining

[0017] The alloy powder ingot melt of S2 is heated and the vacuum degree is increased to carry out refining treatment to obtain a refined melt;

[0018] S4, Alloy Powder Ingot Enhancement and Refining

[0019] The S3 refined melt is further heated and the vacuum degree is increased to extend the refining time. The electromagnetic stirring state is turned on to carry out high-temperature melt strengthening and refining treatment to obtain a strengthened refined melt.

[0020] S5, Coarse Powder Return Ingot Casting

[0021] First, the enhanced and refined melt of S4 is heated to the casting temperature; then the enhanced and refined melt is cast through an Al2O3 ceramic filter to obtain coarse powder return ingots.

[0022] Preferably, the binder in S1 is pectin [C5H] 10 O5], dextrin [(C6H] 10 O5) n ], fructose [C6H 12 O6], amylopectin [(C6H 10 O5) n ·xH2O], potato starch [(C6H 10 At least one of O5)n].

[0023] Preferably, in S1, the weight ratio of binder to coarse powder return material during molding is 1:1000-1:200; and the weight fraction of water added is 2-6 wt.%, the stirring time is 10-20 min, the heating temperature during drying is 100-150℃, and the drying time is 4-8 h.

[0024] Preferably, in S1, the forming is carried out in a mold, and the drying is carried out in a drying oven. The drying process requires that the moisture in the dough-like coarse powder return material be completely evaporated.

[0025] Preferably, the compressive strength of the alloy powder ingot in S1 is 5-50 MPa, and the elongation is 0.1-1%.

[0026] Preferably, the new alloy ingot in S2 is a new alloy ingot of FGH96; and the smelting process is applicable to the smelting of recycled high-temperature alloy coarse powder of FGH95, FGH96, and FGH97.

[0027] Preferably, the vacuum degree of melting in S2 is <8 Pa.

[0028] Preferably, the refining temperature in S3 is 1500-1650℃, the vacuum degree is <1Pa, and the refining time is 15-30min.

[0029] Preferably, the further heating in the enhanced refining process in S4 needs to reach a superheat of 200-350℃. The electromagnetic stirring adopts a three-phase power frequency stirring method with a frequency of 40-70Hz, the refining time is 10-15min, and the casting temperature is 1550-1700℃.

[0030] Preferably, the enhanced refining process in S4 is achieved by using high-temperature melt treatment and strong electromagnetic stirring to enhance the refining process, which causes small particulate oxide inclusions to aggregate and dissolve. This is further enhanced by increasing the vacuum level and extending the refining time to achieve deep removal of [O], [N], and [H].

[0031] Preferably, the amount of coarse powder recycled material added to the coarse powder recycled material ingot in S5 reaches 30-70 wt.%, and the inclusion number density is 1-6 inclusions / mm. 2 The average size of the inclusions is 1-4 μm.

[0032] Preferably, the composition of the coarse powder return ingot in S5, by mass percentage, is: C 0.035-0.065%, Co 12.5-13.5%, Cr 15.5-16.5%, W 3.8-4.2%, Mo 3.8-4.2%, Al 1.95-2.30%, Ti 3.55-3.90%, Zr 0.03-0.06%, Nb 0.6-0.8%, Si≤0.1%, S≤0.0012%, N≤0.005%, O≤0.003%, H≤0.001%, with the balance being Ni.

[0033] Preferably, the room temperature mechanical properties of the coarse powder return ingot in S5 are: tensile strength of 1550-1620 MPa, yield strength of 1100-1250 MPa, and elongation of 20-29%; and the high temperature mechanical properties at 600-700℃ are: tensile strength of 1450-1520 MPa, yield strength of 1000-1150 MPa, and elongation of 25-45%.

[0034] The above technical solution has at least the following advantages compared with the existing technology:

[0035] The above-mentioned solution proposes a method for remelting recycled high-temperature alloy coarse powder, which can solve the technical problems in the prior art, such as difficulty in forming high-temperature alloy coarse powder before melting, severe vacuum powder suction, difficulty in powder heat conduction and transfer, difficulty in removing oxide inclusions and deep removal of [O] and [N]. This makes the size and content of oxygen, nitrogen, sulfur, hydrogen and inclusions in the prepared high-temperature alloy ingots very low, and the hydrogen content can be very low.

[0036] The binder of this invention uses pectin and other components that have strong adhesion to metal powder. A small amount of pectin can achieve the effect of forming metal powder ingots, achieving powder forming before melting and solving technical problems such as vacuum powder suction. Moreover, the C:O ratio in the binder is 1:1, and the introduced C is consumed internally, providing high-quality raw materials for subsequent melting, saving production costs, simplifying process steps, and eliminating the need for additional refining and adding raw materials.

[0037] This invention achieves the aggregation and dissolution of small-particle oxide inclusions by using a reasonable ratio of binder to coarse powder return material, a ratio of alloy powder ingots to new alloy ingots, a two-stage refining process, high-temperature melt treatment, and strong electromagnetic stirring, thereby reducing the size and quantity of inclusions. Then, by increasing the vacuum degree and extending the refining time, [O], [N], and [H] are deeply removed, with the [H] content reaching as low as a few tenths of a ppm.

[0038] The present invention has a relatively short smelting time, can process a large amount of coarse powder return material per furnace, and has a similar technical solution to industrial production. The obstacles to technology transfer can be anticipated and solved. The process steps are convenient, and the composition of the prepared high-temperature alloy, except for [C], [O] and [N], meets the alloy standard requirements of new alloy ingots.

[0039] In summary, compared with other traditional methods, the method of the present invention, through the selection of binder composition content, avoids technical problems such as difficulty in forming high-temperature alloy coarse powder, severe vacuum powder suction, difficulty in powder heat conduction and transfer, difficulty in removing oxide inclusions, and difficulty in deep removal of [O] and [N] during the forming and melting process of alloy powder ingots. It is simple to operate, has low production cost, high efficiency, and is conducive to large-scale industrial production and promotion. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a process flow diagram of a method for remelting recycled powder of high-temperature alloy coarse powder according to the present invention.

[0042] Figure 2 This is a comparison of the macroscopic morphology of metal powder ingots with different binder contents in a method for remelting recycled powder of high-temperature alloy powder according to the present invention.

[0043] Figure 3The present invention relates to a method for remelting recycled coarse powder of a high-temperature alloy, which shows the effect of different binder contents in 50% of the recycled coarse powder on the microstructure of the master alloy ingot; wherein: Figure (a) shows the low-magnification microstructure when the pectin content is 0.1 wt.%, Figure (b) shows the low-magnification microstructure when the pectin content is 0.5 wt.%, Figure (c) shows the high-magnification microstructure when the pectin content is 0.1 wt.%, and Figure (d) shows the high-magnification microstructure when the pectin content is 0.5 wt.%. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0045] This invention proposes a method for remelting recycled powder high-temperature alloy coarse powder, wherein the method for remelting recycled powder high-temperature alloy coarse powder combines... Figure 1 As shown below:

[0046] S1. Coarse powder return material forming

[0047] The binder and recycled coarse powder are mixed, then water is added and stirred to form a dough-like coarse powder. This dough-like coarse powder is then shaped and dried to obtain alloy powder ingots. Figure 2 Comparison of macroscopic morphologies of metal powder ingots with different binder contents in the purification and smelting method of high-temperature alloy containing coarse powder return material is presented;

[0048] S2, Alloy powder ingot smelting

[0049] The new alloy ingot and the S1 alloy powder ingot are placed together in a vacuum induction melting furnace for melting to obtain the alloy powder ingot melt;

[0050] S3, Alloy Powder Refining

[0051] The alloy powder ingot melt of S2 is heated and the vacuum degree is increased to carry out refining treatment to obtain a refined melt;

[0052] S4, Alloy Powder Ingot Enhancement and Refining

[0053] The S3 refined melt is further heated and the vacuum degree is increased to extend the refining time. The electromagnetic stirring state is turned on to carry out high-temperature melt strengthening and refining treatment to obtain a strengthened refined melt.

[0054] S5, Coarse Powder Return Ingot Casting

[0055] First, the enhanced and refined melt of S4 is heated to the casting temperature; then the enhanced and refined melt is cast through an Al2O3 ceramic filter to obtain coarse powder return ingots.

[0056] Specifically, the binder in S1 is pectin [C5H] 10 O5], dextrin [(C6H] 10 O5) n ], fructose [C6H 12 O6], amylopectin [(C6H 10 O5) n ·xH2O], potato starch [(C6H 10 At least one of O5)n].

[0057] Specifically, in S1, the weight ratio of binder to coarse powder return material during molding is 1:1000-1:200; and the weight fraction of water added is 2-6 wt.%, the stirring time is 10-20 min, the heating temperature during drying is 100-150℃, and the drying time is 4-8 h.

[0058] Specifically, in S1, forming takes place in a mold, and drying takes place in a drying oven. Drying requires that the moisture in the dough-like coarse powder return material be completely evaporated.

[0059] Specifically, the compressive strength of the alloy powder ingot in S1 is 5-50 MPa, and the elongation is 0.1-1%.

[0060] Specifically, the new alloy ingot in S2 is a new alloy ingot of FGH96; and this smelting process is applicable to the smelting of recycled high-temperature alloy coarse powder of FGH95, FGH96, and FGH97.

[0061] Specifically, the vacuum level during melting in S2 is <8 Pa.

[0062] Specifically, the refining process in S3 is carried out at a temperature of 1500-1650℃, a vacuum degree of <1Pa, and a refining time of 15-30min.

[0063] Specifically, the further heating of the enhanced refining process in S4 needs to reach a superheat of 200-350℃. The electromagnetic stirring adopts a three-phase power frequency stirring method with a frequency of 40-70Hz, the refining time is 10-15min, and the casting temperature is 1550-1700℃.

[0064] In particular, the enhanced refining process in S4 is achieved by using high-temperature melt treatment and strong electromagnetic stirring to enhance the refining process, which causes small particulate oxide inclusions to aggregate and dissolve. This is further enhanced by increasing the vacuum level and extending the refining time to achieve deep removal of [O], [N], and [H].

[0065] Specifically, the amount of coarse powder recycled material added to the S5 coarse powder recycled material ingot reaches 30-70 wt.%, and the inclusion number density is 1-6 inclusions / mm. 2 The average size of the inclusions is 1-4 μm.

[0066] Specifically, the composition of the coarse powder return ingot in S5, by mass percentage, is: C 0.035-0.065%, Co 12.5-13.5%, Cr 15.5-16.5%, W 3.8-4.2%, Mo 3.8-4.2%, Al 1.95-2.30%, Ti 3.55-3.90%, Zr 0.03-0.06%, Nb 0.6-0.8%, Si≤0.1%, S≤0.0012%, N≤0.005%, O≤0.003%, H≤0.001%, with the balance being Ni.

[0067] Specifically, the room temperature mechanical properties of the coarse powder return ingot in S5 are: tensile strength of 1550-1620 MPa, yield strength of 1100-1250 MPa, and elongation of 20-29%; the high temperature mechanical properties at 600-700℃ are: tensile strength of 1450-1520 MPa, yield strength of 1000-1150 MPa, and elongation of 25-45%.

[0068] In Examples 1-3, a 10kg vacuum induction melting furnace was used to test the FGH96 alloy, with 4kg melted per furnace. The binder content was 0.1wt.%; the recycled coarse powder contained [%C]=0.03wt.%, [%O]=0.0245wt.%, and [%N]=0.003wt.%, with the remaining elements meeting the FGH96 alloy standard requirements.

[0069] Example 1

[0070] A method for remelting recycled powder superalloy coarse powder, the method being as follows:

[0071] S1. Coarse powder return material forming

[0072] Add 2g of pectin binder to 2000g of coarse powder recycled material, add water, and mix manually until the coarse powder recycled material containing binder becomes dough-like coarse powder recycled material; then shape the dough-like coarse powder recycled material in a mold to obtain a metal powder ingot blank; heat the shaped metal powder ingot to 100℃ in a drying oven and dry for 4 hours until the moisture is completely evaporated to obtain an alloy powder ingot; wherein, the compressive strength of the alloy powder ingot is 1.3MPa;

[0073] S2, Alloy powder ingot smelting

[0074] The prepared alloy powder ingot and 2000g of new material were placed in a vacuum induction melting furnace, and the vacuum degree was increased to <8 Pa and the power was increased to 30 kW to melt the alloy powder ingot and obtain the alloy powder ingot melt.

[0075] S3, Alloy Powder Refining

[0076] When there are no obvious floating objects on the surface of the S2 alloy powder ingot melt, the temperature is raised to 1500℃ and the vacuum degree is <1Pa. The refining is carried out for 25 minutes to remove gases such as [O], [N], and [H], and to promote the floating of non-metallic inclusions, thus obtaining a refined melt.

[0077] S4, Alloy Powder Ingot Enhancement and Refining

[0078] The S3 refined melt was heated to 1680℃, and then stirred with electromagnetic stirring at 50Hz for 15 minutes. Through high-temperature melt treatment and strong electromagnetic stirring to enhance refining, small particulate oxide inclusions were aggregated and dissolved. In addition, the vacuum degree was increased and the refining time was extended to achieve deep de-O, N and H removal, resulting in a strengthened refined melt.

[0079] S5, Coarse Powder Return Ingot Casting

[0080] First, the enhanced and refined melt of S4 is further heated until a casting temperature of 1600℃ is reached; then, the enhanced and refined melt is cast through an Al2O3 ceramic filter to obtain a coarse powder return ingot; wherein, the coarse powder return ingot has a coarse powder return material addition amount of 50wt.% and an inclusion number density of 2.38 inclusions / mm. 2 The average size of the inclusions is 1.3 μm; the composition of the coarse powder return ingot, by mass percentage, is C 0.046%, Co 13.13%, Cr 15.53%, W 4.02%, Mo 4.10%, Al 2.18%, Ti 3.76%, Zr 0.045%, Nb 0.7%, Si 0.0180%, S 0.00034%, N 0.0005%, O 0.0012%, H 0.00007%, with the balance being Ni.

[0081] The room temperature mechanical properties of the coarse powder return ingot are: tensile strength of 1618.2 MPa, yield strength of 1246.8 MPa, and elongation of 20.94%; the high temperature mechanical properties at 650℃ are: tensile strength of 1514.8 MPa, yield strength of 1121.3 MPa, and elongation of 35.64%.

[0082] Example 2

[0083] A method for remelting recycled powder superalloy coarse powder, the method being as follows:

[0084] S1. Coarse powder return material forming

[0085] Add 2g of dextrin binder to 2000g of coarse powder recycled material, add water, and mix manually until the coarse powder recycled material containing binder becomes dough-like coarse powder recycled material; then shape the dough-like coarse powder recycled material in a mold to obtain a metal powder ingot blank; heat the shaped metal powder ingot to 100℃ in a drying oven and dry for 4 hours until the moisture is completely evaporated to obtain an alloy powder ingot; wherein, the compressive strength of the alloy powder ingot is 1.1MPa;

[0086] S2, Alloy powder ingot smelting

[0087] The prepared alloy powder ingot and 2000g of new material were placed in a vacuum induction melting furnace, and the vacuum degree was increased to <8 Pa and the power was increased to 30 kW to melt the alloy powder ingot and obtain the alloy powder ingot melt.

[0088] S3, Alloy Powder Refining

[0089] When there are no obvious floating objects on the surface of the S2 alloy powder ingot melt, the temperature is raised to 1500℃ and the vacuum degree is <1Pa. The refining is carried out for 25 minutes to remove gases such as [O], [N], and [H], and to promote the floating of non-metallic inclusions, thus obtaining a refined melt.

[0090] S4, Alloy Powder Ingot Enhancement and Refining

[0091] The S3 refined melt was heated to 1680℃, and then stirred with electromagnetic stirring at 50Hz for 15 minutes. Through high-temperature melt treatment and strong electromagnetic stirring to enhance refining, small particulate oxide inclusions were aggregated and dissolved. In addition, the vacuum degree was increased and the refining time was extended to achieve deep de-O, N and H removal, resulting in a strengthened refined melt.

[0092] S5, Coarse Powder Return Ingot Casting

[0093] First, the enhanced and refined melt of S4 is further heated until a casting temperature of 1600℃ is reached; then, the enhanced and refined melt is cast through an Al2O3 ceramic filter to obtain coarse powder return ingots; wherein, the amount of coarse powder return material added to the coarse powder return ingots reaches 50 wt.%, and the inclusion number density is 2.32 inclusions / mm. 2 The average size of the inclusions is 1.4 μm; the composition of the coarse powder return ingot, by mass percentage, is C 0.048%, Co 13.12%, Cr 15.56%, W 4.08%, Mo 4.10%, Al 2.20%, Ti 3.72%, Zr 0.043%, Nb 0.7%, Si 0.0160%, S 0.00035%, N 0.0004%, O 0.0011%, H 0.00007%, with the balance being Ni.

[0094] The room temperature mechanical properties of the coarse powder return ingot are: tensile strength of 1610.8 MPa, yield strength of 1248.8 MPa, and elongation of 25.89%; the high temperature mechanical properties at 650 ℃ are: tensile strength of 1503.2 MPa, yield strength of 1114.0 MPa, and elongation of 31.21%.

[0095] Example 3

[0096] A method for remelting recycled powder superalloy coarse powder, the method being as follows:

[0097] S1. Coarse powder return material forming

[0098] 2.8g of pectin binder was added to 2800g of coarse powder recycled material, water was added, and the mixture was manually mixed until the coarse powder recycled material containing binder became dough-like. The dough-like coarse powder recycled material was then shaped in a mold to obtain a metal ingot blank. The shaped metal ingot was heated to 100℃ in a drying oven and dried for 4 hours until the moisture was completely evaporated to obtain an alloy ingot. The compressive strength of the alloy ingot was 1.4MPa.

[0099] S2, Alloy powder ingot smelting

[0100] The prepared alloy powder ingot and 1200g of new material were placed in a vacuum induction melting furnace, and the vacuum degree was increased to <8 Pa and the power was increased to 30 kW to melt the alloy powder ingot and obtain the alloy powder ingot melt.

[0101] S3, Alloy Powder Refining

[0102] When there are no obvious floating objects on the surface of the S2 alloy powder ingot melt, the temperature is raised to 1500℃ and the vacuum degree is <1Pa. The refining is carried out for 25 minutes to remove gases such as [O], [N], and [H], and to promote the floating of non-metallic inclusions, thus obtaining a refined melt.

[0103] S4, Alloy Powder Ingot Enhancement and Refining

[0104] The S3 refined melt was heated to 1680℃, and then stirred with electromagnetic stirring at 50Hz for 15 minutes. Through high-temperature melt treatment and strong electromagnetic stirring to enhance refining, small particulate oxide inclusions were aggregated and dissolved. In addition, the vacuum degree was increased and the refining time was extended to achieve deep de-O, N and H removal, resulting in a strengthened refined melt.

[0105] S5, Coarse Powder Return Ingot Casting

[0106] First, the enhanced and refined melt of S4 is further heated until a casting temperature of 1600℃ is reached; then, the enhanced and refined melt is cast through an Al2O3 ceramic filter to obtain coarse powder return ingots; wherein, the amount of coarse powder return material added to the coarse powder return ingots reaches 70 wt.%, and the inclusion number density is 2.52 inclusions / mm. 2 The average size of the inclusions was 1.26 μm. The composition of the coarse powder return ingot, by mass percentage, was C 0.045%, Co 13.06%, Cr 15.55%, W 3.99%, Mo 4.13%, Al 2.17%, Ti 3.82%, Zr 0.042%, Nb 0.7%, Si 0.03%, S 0.0004%, N 0.0007%, O 0.001%, H 0.00008%, with the balance being Ni.

[0107] The room temperature mechanical properties of the coarse powder return ingot are: tensile strength of 1619.8 MPa, yield strength of 1244.6 MPa, and elongation of 21.64%; the high temperature mechanical properties at 650℃ are: tensile strength of 1518.6 MPa, yield strength of 1123.5 MPa, and elongation of 34.61%.

[0108] Examples 4-6 use a 10kg vacuum induction melting furnace to test FGH96 alloy, melting 4kg per furnace; the binder content is 0.5wt.%; the recycled coarse powder contains [%C]=0.03wt.%, [%O]=0.0245wt.%, and [%N]=0.003wt.%, and the remaining elements meet the FGH96 alloy standard requirements.

[0109] like Figure 2 As shown, the macroscopic morphology of metal powder ingots with different binder contents of 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 1.0%, 3.0%, and 5.0% in the method of remelting recycled high-temperature alloy powder is shown.

[0110] Example 4

[0111] A method for remelting recycled powder superalloy coarse powder, the method being as follows:

[0112] S1. Coarse powder return material forming

[0113] 10g of pectin binder was added to 2000g of coarse powder recycled material, water was added, and the mixture was manually stirred until the coarse powder recycled material containing binder became dough-like. The dough-like coarse powder recycled material was then shaped in a mold to obtain a preliminary metal ingot blank. The shaped metal ingot was heated to 100℃ in a drying oven and dried for 4 hours until the moisture was completely evaporated to obtain an alloy ingot. The compressive strength of the alloy ingot was 23MPa.

[0114] S2, Alloy powder ingot smelting

[0115] The prepared alloy powder ingot and 2000g of new material were placed in a vacuum induction melting furnace, and the vacuum degree was increased to <8 Pa and the power was increased to 30 kW to melt the alloy powder ingot and obtain the alloy powder ingot melt.

[0116] S3, Alloy Powder Refining

[0117] When there are no obvious floating objects on the surface of the S2 alloy powder ingot melt, the temperature is raised to 1500℃ and the vacuum degree is <1Pa. The refining is carried out for 25 minutes to remove gases such as [O], [N], and [H], and to promote the floating of non-metallic inclusions, thus obtaining a refined melt.

[0118] S4, Alloy Powder Ingot Enhancement and Refining

[0119] The S3 refined melt was heated to 1680℃, and then stirred with electromagnetic stirring at 50Hz for 15 minutes. Through high-temperature melt treatment and strong electromagnetic stirring to enhance refining, small particulate oxide inclusions were aggregated and dissolved. In addition, the vacuum degree was increased and the refining time was extended to achieve deep de-O, N and H removal, resulting in a strengthened refined melt.

[0120] S5, Coarse Powder Return Ingot Casting

[0121] First, the enhanced and refined melt of S4 is further heated until a casting temperature of 1600℃ is reached; then, the enhanced and refined melt is cast through an Al2O3 ceramic filter to obtain a coarse powder return ingot; wherein, the amount of coarse powder return material added to the coarse powder return ingot reaches 50 wt.%, and the inclusion number density is 3.27 inclusions / mm. 2 The average size of the inclusions was 1.9 μm. The composition of the coarse powder return ingot, by mass percentage, was C 0.047%, Co 13.05%, Cr 16.13%, W 3.97%, Mo 3.92%, Al 2.03%, Ti 3.62%, Zr 0.043%, Nb 0.7%, Si 0.023%, S 0.00043%, N 0.00060%, O 0.0014%, H 0.00007%, with the balance being Ni.

[0122] The room temperature mechanical properties of the coarse powder return ingot are: tensile strength of 1615.1 MPa, yield strength of 1246.7 MPa, and elongation of 21.39%; the high temperature mechanical properties at 650℃ are: tensile strength of 1512.2 MPa, yield strength of 1115.3 MPa, and elongation of 32.79%.

[0123] Example 5

[0124] A method for remelting recycled powder superalloy coarse powder, the method being as follows:

[0125] S1. Coarse powder return material forming

[0126] 10g of dextrin binder was added to 2000g of coarse powder recycled material, water was added, and the mixture was manually mixed until the coarse powder recycled material containing binder became dough-like. The dough-like coarse powder recycled material was then shaped in a mold to obtain a metal ingot blank. The shaped metal ingot was heated to 100℃ in a drying oven and dried for 4 hours until the moisture was completely evaporated to obtain an alloy ingot. The strength of the alloy ingot was 19MPa.

[0127] S2, Alloy powder ingot smelting

[0128] The prepared alloy powder ingot and 2000g of new material were placed in a vacuum induction melting furnace, and the vacuum degree was increased to <8 Pa and the power was increased to 30 kW to melt the alloy powder ingot and obtain the alloy powder ingot melt.

[0129] S3, Alloy Powder Refining

[0130] When there are no obvious floating objects on the surface of the S2 alloy powder ingot melt, the temperature is raised to 1500℃ and the vacuum degree is <1Pa. The refining is carried out for 25 minutes to remove gases such as [O], [N], and [H], and to promote the floating of non-metallic inclusions, thus obtaining a refined melt.

[0131] S4, Alloy Powder Ingot Enhancement and Refining

[0132] The S3 refined melt was heated to 1680℃, and then stirred with electromagnetic stirring at 50Hz for 15 minutes. Through high-temperature melt treatment and strong electromagnetic stirring to enhance refining, small particulate oxide inclusions were aggregated and dissolved. In addition, the vacuum degree was increased and the refining time was extended to achieve deep de-O, N and H removal, resulting in a strengthened refined melt.

[0133] S5, Coarse Powder Return Ingot Casting

[0134] First, the enhanced and refined melt of S4 is further heated until a casting temperature of 1600℃ is reached; then, the enhanced and refined melt is cast through an Al2O3 ceramic filter to obtain a coarse powder return ingot; wherein, the amount of coarse powder return material added to the coarse powder return ingot reaches 50 wt.%, and the inclusion number density is 3.13 inclusions / mm. 2 The average size of the inclusions is 1.7 μm; the composition of the coarse powder return ingot, by mass percentage, is C 0.049%, Co 13.26%, Cr 15.85%, W 3.92%, Mo 3.98%, Al 2.14%, Ti 3.68%, Zr 0.051%, Nb 0.7%, Si 0.0260%, S 0.00038%, N 0.00050%, O 0.0014%, H 0.00006%, with the balance being Ni.

[0135] The room temperature mechanical properties of the coarse powder return ingot are: tensile strength of 1609.8 MPa, yield strength of 1248.6 MPa, and elongation of 23.81%; the high temperature mechanical properties at 650 ℃ are: tensile strength of 1517.2 MPa, yield strength of 1119.3 MPa, and elongation of 31.56%.

[0136] Example 6

[0137] A method for remelting recycled powder superalloy coarse powder, the method being as follows:

[0138] S1. Coarse powder return material forming

[0139] 14g of pectin binder was added to 2800g of coarse powder recycled material, water was added, and the mixture was manually mixed until the coarse powder recycled material containing binder became dough-like. The dough-like coarse powder recycled material was then shaped in a mold to obtain a preliminary metal ingot blank. The shaped metal ingot was heated to 100℃ in a drying oven and dried for 4 hours until the moisture was completely evaporated to obtain an alloy ingot. The strength of the alloy ingot was 27MPa.

[0140] S2, Alloy powder ingot smelting

[0141] The prepared alloy powder ingot and 1200g of new material were placed in a vacuum induction melting furnace, and the vacuum degree was increased to <8 Pa and the power was increased to 30 kW to melt the alloy powder ingot and obtain the alloy powder ingot melt.

[0142] S3, Alloy Powder Refining

[0143] When there are no obvious floating objects on the surface of the S2 alloy powder ingot melt, the temperature is raised to 1500℃ and the vacuum degree is <1Pa. The refining is carried out for 25 minutes to remove gases such as [O], [N], and [H], and to promote the floating of non-metallic inclusions, thus obtaining a refined melt.

[0144] S4, Alloy Powder Ingot Enhancement and Refining

[0145] The S3 refined melt was heated to 1680℃, and then stirred with electromagnetic stirring at 50Hz for 15 minutes. Through high-temperature melt treatment and strong electromagnetic stirring to enhance refining, small particulate oxide inclusions were aggregated and dissolved. In addition, the vacuum degree was increased and the refining time was extended to achieve deep de-O, N and H removal, resulting in a strengthened refined melt.

[0146] S5, Coarse Powder Return Ingot Casting

[0147] First, the enhanced and refined melt of S4 is further heated until a casting temperature of 1600℃ is reached; then, the enhanced and refined melt is cast through an Al2O3 ceramic filter to obtain coarse powder return ingots; wherein, the amount of coarse powder return material added to the coarse powder return ingots reaches 70 wt.%, and the inclusion number density is 2.98 inclusions / mm. 2 The average size of the inclusions was 1.42 μm. The composition of the coarse powder return ingot, by mass percentage, was C 0.051%, Co 13.18%, Cr 15.71%, W 4.12%, Mo 4.08%, Al 2.09%, Ti 3.71%, Zr 0.051%, Nb 0.7%, Si 0.028%, S 0.00036%, N 0.0006%, O 0.0015%, H 0.00007%, with the balance being Ni.

[0148] The room temperature mechanical properties of the coarse powder return ingot are: tensile strength of 1619.2 MPa, yield strength of 1246.7 MPa, and elongation of 21.6%; the high temperature mechanical properties at 650℃ are: tensile strength of 1516.4 MPa, yield strength of 1122.3 MPa, and elongation of 32.21%.

[0149] like Figure 3 As shown, by comparing the macroscopic morphology of metal powder ingots with pectin content of 0.1% and 0.5% in the method of remelting recycled high-temperature alloy coarse powder containing 50% powder, it can be found that as the binder content gradually increases, the dendrites and dendrite gaps decrease.

[0150] The above-mentioned solution proposes a method for remelting recycled high-temperature alloy coarse powder, which can solve the technical problems in the prior art, such as difficulty in forming high-temperature alloy coarse powder before melting, severe vacuum powder suction, difficulty in powder heat conduction and transfer, difficulty in removing oxide inclusions and deep removal of [O] and [N]. This makes the size and content of oxygen, nitrogen, sulfur, hydrogen and inclusions in the prepared high-temperature alloy ingots very low, and the hydrogen content can be very low.

[0151] The binder of this invention uses pectin and other components that have strong adhesion to metal powder. A small amount of pectin can achieve the effect of forming metal powder ingots, achieving powder forming before melting and solving technical problems such as vacuum powder suction. Moreover, the C:O ratio in the binder is 1:1, and the introduced C is consumed internally, providing high-quality raw materials for subsequent melting, saving production costs, simplifying process steps, and eliminating the need for additional refining and adding raw materials.

[0152] This invention achieves the aggregation and dissolution of small-particle oxide inclusions by using a reasonable ratio of binder to coarse powder return material, a ratio of alloy powder ingots to new alloy ingots, a two-stage refining process, high-temperature melt treatment, and strong electromagnetic stirring, thereby reducing the size and quantity of inclusions. Then, by increasing the vacuum degree and extending the refining time, [O], [N], and [H] are deeply removed, with the [H] content reaching as low as a few tenths of a ppm.

[0153] The present invention has a relatively short smelting time, can process a large amount of coarse powder return material per furnace, and has a similar technical solution to industrial production. The obstacles to technology transfer can be anticipated and solved. The process steps are convenient, and the composition of the prepared high-temperature alloy, except for [C], [O] and [N], meets the alloy standard requirements of new alloy ingots.

[0154] In summary, compared with other traditional methods, the method of the present invention, through the selection of binder composition content, avoids technical problems such as difficulty in forming high-temperature alloy coarse powder, severe vacuum powder suction, difficulty in powder heat conduction and transfer, difficulty in removing oxide inclusions, and difficulty in deep removal of [O] and [N] during the forming and melting process of alloy powder ingots. It is simple to operate, has low production cost, high efficiency, and is conducive to large-scale industrial production and promotion.

[0155] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for remelting recycled powder of high-temperature alloy coarse powder, characterized in that, The method for remelting the recycled high-temperature alloy powder coarse powder is as follows: S1. Coarse powder return material forming The binder and coarse powder return material are mixed, then water is added and stirred to make it into dough-like coarse powder. The dough-like coarse powder return material is then shaped and dried to obtain alloy powder ingots. The binder is at least one of pectin, dextrin, fructose, amylopectin, and potato starch. The weight ratio of binder to coarse powder return material during shaping is 1:1000-1:

200. S2, Alloy powder ingot smelting The new alloy ingot and the alloy powder ingot of S1 are placed together in a vacuum induction melting furnace for melting to obtain alloy powder ingot melt; the new alloy ingot is the new alloy ingot of FGH96; and this melting process is applicable to the melting of FGH95, FGH96 and FGH97 high temperature alloy coarse powder return materials. S3, Alloy Powder Refining The alloy powder ingot melt of S2 is heated and the vacuum degree is increased to carry out refining treatment to obtain a refined melt; S4, Alloy Powder Ingot Enhancement and Refining The S3 refined melt is further heated and the vacuum degree is increased to extend the refining time. The electromagnetic stirring state is turned on to carry out high-temperature melt strengthening and refining treatment to obtain a strengthened refined melt. S5, Coarse Powder Return Ingot Casting First, the enhanced and refined melt of S4 is heated to the casting temperature; then the enhanced and refined melt is cast through an Al2O3 ceramic filter to obtain coarse powder return ingots.

2. The method for remelting recycled high-temperature alloy powder according to claim 1, characterized in that, The water added to S1 has a weight fraction of 2-6 wt.%, the stirring time is 10-20 min, the heating temperature during drying is 100-150℃, and the drying time is 4-8 h.

3. The method for remelting recycled powder of high-temperature alloy coarse powder according to claim 1, characterized in that, The vacuum degree of smelting in S2 is <8Pa.

4. The method for remelting recycled powder of high-temperature alloy coarse powder according to claim 1, characterized in that, The refining process in S3 is carried out at a temperature of 1500-1650℃, a vacuum degree of <1Pa, and a refining time of 15-30min.

5. The method for remelting recycled powder of high-temperature alloy coarse powder according to claim 1, characterized in that, In S4, the further heating for enhanced refining requires a superheat of 200-350℃. The electromagnetic stirring adopts a three-phase power frequency stirring method with a frequency of 40-70Hz, the refining time is 10-15min, and the casting temperature is 1550-1700℃.

6. The method for remelting recycled powder of high-temperature alloy coarse powder according to claim 1, characterized in that, The amount of coarse powder recycled material added to the S5 coarse powder recycled material ingot reaches 30-70 wt.%, and the inclusion number density is 1-6 particles / mm. 2 .

7. The method for remelting recycled powder of high-temperature alloy coarse powder according to claim 1, characterized in that, The composition of the coarse powder return ingot in S5, by mass percentage, is: C 0.035-0.065%, Co 12.5-13.5%, Cr 15.5-16.5%, W 3.8-4.2%, Mo 3.8-4.2%, Al 1.95-2.30%, Ti 3.55-3.90%, Zr 0.03-0.06%, Nb 0.6-0.8%, Si≤0.1%, S≤0.0012%, N≤0.005%, O≤0.003%, H≤0.001%, with the balance being Ni.

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