A method for manufacturing high-temperature alloy powder remelting master alloy

Abstract

The invention discloses a method for manufacturing a high-temperature alloy powder remelting master alloy. Through a first furnace production method and a second furnace production method, block materials and waste alloy powder in the furnace are placed in an interlaced and stacked state. Then, the high-temperature alloy remelting master alloy is obtained by melting through electric heating under a low vacuum state and refining and pouring under a high vacuum state. The method solves the problem of difficulty in remelting high-temperature alloy powder under a vacuum state, avoids mixing with binders such as paraffin wax, rubber, polyethylene glycol and glycerol, and eliminates the problem of increased oxygen and nitrogen impurities in non-vacuum melting, thereby ensuring the composition and performance of the master alloy.

Description

Technical Field

[0001] The present invention relates to the technical field of high-temperature alloys, and in particular to a method for manufacturing a high-temperature alloy powder remelting master alloy. Background Art

[0002] High-temperature alloy 3D printing is a new technology that has flourished in recent years, primarily used in a variety of high-end industries, including heat-resistant, high-strength molds, medical devices, and aerospace. As my country's traditional industries upgrade and gradually catch up with advanced international standards, these high-end industries are increasingly demanding high-temperature alloy 3D printing. High-temperature alloy powder is one of the core technologies used in high-temperature alloy 3D printing. Conventional 3D printing uses powders with diameters ranging from 15μm to 53μm. Therefore, approximately 50% of high-temperature alloy powders smaller than 15 microns and larger than 53 microns cannot be directly used.

[0003] Furthermore, powder-coated superalloy turbine discs are the preferred material for aircraft engine discs with thrust-to-weight ratios exceeding 8. Controlling the size and quantity of non-metallic inclusions in superalloy powders is a global challenge. The current common approach is to use fine powder to reduce the maximum inclusion size, fundamentally limiting the potential size of non-metallic inclusions, thereby improving the inherent metallurgical quality of the powder-coated turbine discs. This is a key measure for ensuring disc reliability. Currently, the maximum size of powder particles must not exceed 106μm. Powder particles for critical components are ≤53μm, or even ≤45μm, and this size is expected to be further reduced in the future.

[0004] The particle size distribution of argon atomized superalloy powder follows a log-normal distribution. It's impossible to use all the powder within the entire particle size range, meaning some coarse powder will always be unused. Currently, the yield of argon atomized superalloy powder with a 270 mesh (≤53μm) fine powder is 60%, meaning approximately 40% of the coarse powder is unusable.

[0005] Currently, a large amount of coarse powder is left unused after powder screening, resulting in significant waste and keeping the manufacturing cost of powder turbine disks high. With the development and application of advanced aero-engines in my country, the demand for high-quality argon atomized superalloy powder will continue to grow. Currently, the annual demand for superalloy powder has reached over 100 tons, resulting in a large amount of unused and wasted superalloy coarse powder.

[0006] There are two existing methods for recycling superalloy powder. The first is compression molding (briquetting), as exemplified by Chinese patent CN201910810891.X, a method for recycling waste superalloy powder. Superalloy powders possess high hardness and yield strength, making conventional pressure unsustainable. Experiments with cold isostatic pressing at 200 MPa and compression at 400 MPa have shown that the briquettes loosen upon contact with the mold, and the mold deforms and damages during the pressing process. Therefore, alternative measures are typically required. Two solutions are often employed: One is to bond the powders with a binder followed by pressure molding. Commonly used binders include paraffin wax, rubber, polyethylene glycol, and glycerol. While these binders achieve the desired molding effect, they cannot be completely removed during the subsequent heating process. Consequently, their application in superalloy powder recycling inevitably increases the carbon and oxygen content of the powder or introduces other impurities, ultimately affecting the composition and properties of the resulting master alloy. The second method involves uniformly mixing high-temperature alloy powder with its own base pure metal powder before forming. This allows for high-hardness high-temperature alloy powder compression molding, but recycling costs are relatively high. Iron-based powders are reasonable, while nickel- and cobalt-based powders are more expensive. Furthermore, mold and press costs must be considered, resulting in low efficiency. To compact powders at room temperature, at least one of the following conditions must be met: either the pressure must exceed its yield strength by more than 20%, or the powder itself must be microscopically porous or even dendritic, allowing it to embed itself in the powder under excessive pressure. 3D printing waste high-temperature alloy spherical powder, due to its high tensile and yield strength, smooth spherical surface, and excellent fluidity, is not well suited for compression. Compacting requires either increasing the pressing force or reducing the size of the pressed block. Either method significantly impacts recycling efficiency.

[0007] The second method involves combining high-temperature alloy master alloy blocks of selected compositions with high-temperature alloy powder (direct remelting). For example, Chinese patent CN202110769613.1 describes a method for preparing high-temperature alloy powder using nickel-based high-temperature alloy powder return material. This method involves adding the return material in a single batch from a cold furnace, with the return material accounting for no more than 80% of the total weight. However, this method has limitations and cannot be used in continuous hot furnace production, resulting in low production efficiency. Direct remelting of high-temperature alloy powder is difficult. Non-vacuum melting increases oxygen and nitrogen content, and oxidizable elements in the high-temperature alloy oxidize and become impurities. Adding material under vacuum is also difficult, as the added powder is easily extracted under vacuum.

[0008] The large-scale use of 3D printing must solve the problem of reuse, and powders with non-compliant particle sizes must be directly remelted and recycled. Summary of the Invention

[0009] The present invention aims to address at least one of the technical problems existing in the prior art. To this end, the present invention provides a method for producing a master alloy by remelting high-temperature alloy powder. This method solves the difficulty of remelting high-temperature alloy powder in a vacuum state, avoids the presence of binders such as paraffin wax, rubber, polyethylene glycol, and glycerol, and eliminates the problem of increased oxygen and nitrogen impurities associated with non-vacuum melting, thereby ensuring the composition and properties of the master alloy.

[0010] A method for manufacturing a high-temperature alloy powder remelting master alloy according to an embodiment of the first aspect of the present invention is characterized by comprising the following steps:

[0011] a. First Furnace Production Method: The first furnace production is performed in a cold furnace. 20 parts by weight of bulk material is placed at the bottom of the furnace. 30 parts by weight of scrap alloy powder, 10 parts by weight of bulk material, 30 parts by weight of scrap alloy powder, and 10 parts by weight of bulk material are placed in this order from bottom to top. The cold furnace is heated and melted in a low vacuum state (less than 10Pa, with the slide valve vacuum pump and Roots vacuum pump turned on). After the bulk material is melted, the melting power is slightly reduced to prevent the powder return material from splashing. After the powder return material is completely melted, the original melting power is restored.

[0012] b. Refining under high vacuum (less than 0.1Pa, oil booster pump on), sampling and adjusting the composition to meet the requirements, pouring at the process temperature, leaving 20-30 parts by weight of molten metal in the pouring furnace;

[0013] c. Production method for the second furnace: After the molten metal in the second furnace is frozen, the feeding method is adopted. A 300-mesh filter bag (the size of the filter bag is selected according to the feeding bucket) is used to put the scrap alloy powder into the 300-mesh filter bag. A number of block materials are placed on the top of the 300-mesh filter bag. The scrap alloy powder is added into the furnace in several batches. After the weight reaches 80 parts by weight, 10-20 parts by weight of block materials are added on the top. The furnace is melted under low vacuum (less than 10Pa, with the slide valve vacuum pump and Roots vacuum pump turned on). After the block materials are melted, the melting power is slightly reduced to prevent the powder return materials from splashing. After the powder return materials are completely cleared, the original power is restored to melt.

[0014] d. Then, in a high vacuum state (less than 0.1Pa, open the oil booster pump) refining, sampling and adjusting the composition to meet the requirements, pouring at the process temperature, leaving 20-30 parts by weight of the molten metal in the pouring furnace;

[0015] e. For subsequent heats, refer to the production method of the second heat.

[0016] A method for manufacturing a high-temperature alloy powder remelting master alloy according to an embodiment of the present invention has at least the following beneficial effects: this embodiment uses the first furnace production method and the second furnace production method to place the block material and waste alloy powder in the furnace in an interlaced and stacked state, and then obtains the high-temperature alloy remelting master alloy through electric heating and melting under a low vacuum state and refining and pouring under a high vacuum state. This solves the problem of difficulty in remelting high-temperature alloy powder under a vacuum state, avoids the mixing of binders such as paraffin wax, rubber, polyethylene glycol and propylene glycol, and eliminates the problem of increased oxygen and nitrogen impurities in non-vacuum melting, thereby ensuring the composition and performance of the master alloy.

[0017] According to some embodiments of the present invention, the vacuum melting equipment used is a semi-continuous vacuum induction furnace, which includes at least three independent ingot mold chambers, a melting chamber, and an upper feeding chamber.

[0018] According to some embodiments of the present invention, the ingot mold chamber, the smelting chamber, and the upper feeding chamber are externally connected to a sliding valve vacuum pump and / or a Roots vacuum pump through a vacuum pipeline for achieving a low vacuum state in the chamber.

[0019] According to some embodiments of the present invention, the smelting chamber is externally connected to an oil booster pump via a vacuum pipe for achieving a high vacuum state in the chamber.

[0020] According to some embodiments of the present invention, an oil pool filter device capable of filtering powder is installed at one end of the vacuum pipe close to the smelting chamber.

[0021] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments with reference to the following drawings, in which:

[0023] Figure 1 Schematic diagram of the staggered stacking state of block materials and scrap alloy powder in the smelting chamber and the charging chamber according to an embodiment of the present invention;

[0024] Figure 2 Schematic diagram of vacuum melting equipment according to an embodiment of the present invention.

[0025] 100, bulk material; 200, scrap alloy powder; 300, smelting chamber; 400, upper feeding chamber; 410, feeding barrel; 420, filter bag. DETAILED DESCRIPTION

[0026] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0027] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0028] In the description of the present invention, "several" means one or more, "many" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0029] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0030] Reference Figure 1 According to the first embodiment of the present invention, a method for manufacturing a high-temperature alloy powder remelting master alloy comprises the following steps:

[0031] a. Production method for the first furnace: In the first cold furnace production, 20 parts by weight of a block material 100 are placed at the bottom of the furnace, followed by 30 parts by weight of scrap alloy powder 200, 10 parts by weight of the block material 100, 30 parts by weight of the scrap alloy powder 200, and 10 parts by weight of the block material 100 in order from bottom to top. The cold furnace is powered on and heated to melt the block material 100 in a low vacuum state (less than 10 Pa, with the slide valve vacuum pump and Roots vacuum pump turned on). After the block material 100 is melted, the melting power is slightly reduced to prevent the powder return material from splashing. After the powder return material is completely melted, the original power is restored to melt.

[0032] It is worth noting that the block material 100 and the scrap alloy powder 200 in the furnace are in a staggered stacking state, which can prevent the powder return material from splashing, so that the powder is not sucked into the vacuum pipe under the vacuum state to cause material waste;

[0033] b. Refining under high vacuum (less than 0.1Pa, oil booster pump on), sampling and adjusting the composition to meet the requirements, pouring at the process temperature, leaving 20-30 parts by weight of molten metal in the pouring furnace;

[0034] c. Production method for the second furnace: After the molten metal in the second furnace is frozen, the feeding method is adopted, using the feeding barrel 410, and using a 300-mesh filter bag 420 (the size of the filter bag 420 is selected according to the feeding barrel 410). The scrap alloy powder 200 is placed in the 300-mesh filter bag 420, and a number of block materials 100 are placed on the top of the 300-mesh filter bag 420. The scrap alloy powder 200 is added to the furnace in several batches. After reaching 80 parts by weight, 10-20 parts by weight of block materials 100 are added to the top. The furnace is powered down and melted in a low vacuum state (less than 10Pa, with a slide valve vacuum pump and a roots vacuum pump turned on). After the block materials 100 are melted, the melting power is slightly reduced to prevent the powder return material from splashing. After the powder return material is completely melted, the original power is restored to the melting state;

[0035] d. Then, in a high vacuum state (less than 0.1Pa, open the oil booster pump) refining, sampling and adjusting the composition to meet the requirements, pouring at the process temperature, leaving 20-30 parts by weight of the molten metal in the pouring furnace;

[0036] e. For subsequent heats, refer to the production method of the second heat.

[0037] A method for manufacturing a high-temperature alloy powder remelting master alloy according to an embodiment of the present invention has at least the following beneficial effects: in this embodiment, through the first furnace production method and the second furnace production method, the block material 100 and the scrap alloy powder 200 in the furnace are placed in an interlaced and stacked state, and then the high-temperature alloy remelting master alloy is obtained by melting through electric heating under a low vacuum state and refining and pouring under a high vacuum state. This solves the problem of difficult remelting of high-temperature alloy powder under a vacuum state, avoids the mixing of binders such as paraffin wax, rubber, polyethylene glycol and glycerol, and eliminates the problem of increased oxygen and nitrogen impurities in non-vacuum melting, thereby ensuring the composition and performance of the master alloy.

[0038] Reference Figure 2 According to some embodiments of the present invention, the vacuum melting equipment is a semi-continuous vacuum induction furnace, which includes at least three independent ingot mold chambers, a melting chamber 300, and an upper charging chamber 400.

[0039] According to some embodiments of the present invention, the ingot mold chamber, the smelting chamber 300 and the upper feeding chamber 400 are externally connected to a sliding valve vacuum pump and / or a Roots vacuum pump through a vacuum pipeline for achieving a low vacuum state in the chamber.

[0040] According to some embodiments of the present invention, the smelting chamber 300 is externally connected to an oil booster pump via a vacuum pipeline to achieve a high vacuum state within the chamber. The oil booster pump in this embodiment can be combined with valves, pipelines, and a mechanical pump to form a highly efficient medium-vacuum pumping system. Furthermore, the oil booster pump has a higher operating pressure range (10-10 Pa) than an oil diffusion pump. Therefore, in addition to serving as a main pump, the oil booster pump can also serve as a backing pump for sliding valve vacuum pumps and Roots vacuum pumps, providing a boosting effect and achieving ultra-high vacuum.

[0041] According to some embodiments of the present invention, an oil sump filter device capable of filtering powder is installed at one end of the vacuum pipe near the smelting chamber 300. The oil sump filter device filters powder from the vacuum pipe, protecting the subsequent sliding valve vacuum pump, Roots vacuum pump, and oil booster pump.

[0042] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the technical field without departing from the scope of the present invention.

Claims

1. A method for producing a high-temperature alloy powder remelting master alloy, characterized in that: The following steps are involved: a. The first furnace production method: The first furnace production is to place 20 parts by weight of a block material (100) at the bottom of the cold furnace, and then place 30 parts by weight of scrap alloy powder (200), 10 parts by weight of a block material (100), 30 parts by weight of a scrap alloy powder (200), and 10 parts by weight of a block material (100) in the order from bottom to top. The cold furnace is powered on and heated to melt under a low vacuum state. When the block material (100) is melted, the melting power is slightly reduced to prevent the powder return material from splashing. After the powder return material is completely melted, the original power is restored to melt. b. Refining under high vacuum, sampling and adjusting the composition, pouring at the process temperature, leaving 20-30 parts by weight of the molten metal in the pouring furnace; c. Second furnace production method: After the second furnace freezes the molten metal, a feeding barrel (410) is used for feeding, a 300-mesh filter bag (420) is used, and the scrap alloy powder (200) is placed in the 300-mesh filter bag (420). A plurality of block materials (100) are placed on the upper portion of the 300-mesh filter bag (420). The scrap alloy powder (200) is added to the furnace several times. After reaching 80 parts by weight, 10-20 parts by weight of block materials (100) are added to the upper portion. Electricity is supplied for melting under a low vacuum state. After the block materials (100) are melted, the melting power is slightly reduced to prevent the powder return material from splashing. After the powder return material is completely cleared, the original power is restored for melting. d. Then refined in a high vacuum state, sampling and adjusting the composition, pouring at the process temperature, leaving 20-30 parts by weight of the molten metal in the pouring furnace; e. For subsequent heats, refer to the production method of the second heat.

2. The method for manufacturing a high-temperature alloy powder remelting master alloy according to claim 1, characterized in that: The vacuum melting equipment used is a semi-continuous vacuum induction furnace, which comprises at least three mutually independent ingot mold chambers, a melting chamber (300), and an upper charging chamber (400).

3. The method for manufacturing a high-temperature alloy powder remelting master alloy according to claim 2, characterized in that: The ingot mold chamber, the smelting chamber (300), and the upper feeding chamber (400) are externally connected to a slide valve vacuum pump and / or a Roots vacuum pump via vacuum pipes for achieving a low vacuum state in the chambers.

4. The method for manufacturing a high-temperature alloy powder remelting master alloy according to claim 2, characterized in that: The smelting chamber (300) is externally connected to an oil booster pump via a vacuum pipe for achieving a high vacuum state in the chamber.

5. The method for manufacturing a high-temperature alloy powder remelting master alloy according to claim 3 or 4, characterized in that: An oil pool filter device capable of filtering powder is installed at one end of the vacuum pipe close to the smelting chamber (300).

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