A method for preparing a GH4169 alloy dirty white spot material by induction melting

Abstract

The present application relates to the technical field of aero-engine safety airworthiness evaluation, and discloses a method for preparing GH4169 alloy dirty white spot material by using induction melting, which comprises the following steps: on the basis of target GH4169 composition, the Nb content is reduced below the standard range, the reduced element mass is supplemented with Fe, and other elements are kept within the standard range to prepare alloy raw materials; according to the target dirty white spot impurity content requirement, the mass ratio of alloy raw materials to impurity raw materials is calculated to prepare impurity raw materials; by using induction melting technology, the alloy raw materials are heated and melted in a vacuum environment, and at the same time, the impurity raw materials are dispersed in the metal melt; the metal melt after melting is poured into a mold to cool and form dirty white spot ingot material; the present application provides a material basis for subsequent research on defect attribute detection, nondestructive testing of the detection capability of defects, and provides a theoretical and material basis for safety evaluation of aero-engine deformation high-temperature alloy life-limited parts.

Description

Technical Field

[0001] This invention relates to the field of airworthiness assessment technology for aircraft engines, and specifically to a method for preparing GH4169 alloy dirty white spot material using induction melting. Background Technology

[0002] Wrought superalloys are widely used in engine hot-end components due to their excellent performance at high temperatures. However, wrought superalloys may develop dirty white spots during the smelting process, which could lead to catastrophic consequences if left in engine components.

[0003] In 2016, AA383 aborted takeoff from Chicago due to a fracture of its second-stage high-pressure turbine disk. An investigation by the NTSB (National Transportation Safety Board) revealed a dirty white spot at the center of the fractured turbine disk. This defect contributed to fatigue cracking during engine operation, ultimately leading to the disk's rupture. Following the accident, the FAA (Federal Aviation Administration) and EASA (European Aviation Safety Agency) issued a series of emergency airworthiness directives requiring testing of the affected engines. The FAA also collaborated with the AIA (Aeronautical Industries Association) to conduct research on non-destructive testing of dirty white spots and their impact on material fatigue performance.

[0004] However, the number of naturally occurring dirty white spots is small, and their properties are uncontrollable, posing a significant challenge to research. GH4169, as one of the most widely used wrought superalloys, is highly representative in dirty white spot research. Therefore, a new source of defect acquisition is needed to provide materials that conform to the characteristics of dirty white spots, providing a material basis for subsequent research on defect material properties, non-destructive testing, and the impact of defects on material fatigue performance, thus supporting the safety and airworthiness technology of my country's engines. Summary of the Invention

[0005] In view of the above problems, the present invention provides a method for preparing GH4169 alloy dirty white spot material by induction melting, which solves the problem in the prior art of how to produce artificial dirty white spot material with low Nb content and non-metallic impurities.

[0006] This invention provides a method for preparing GH4169 alloy dirty white spot material using induction melting, comprising the following steps:

[0007] Step S1: Prepare alloy raw materials. The element ratio of the alloy raw materials is as follows: Nb < 5%, C 0.015-0.06%, Cr 17-21%, Ni 50-55%, Mo 2.8-3.3%, Al 0.3-0.7%, Ti 0.75-1.15%, B ≤ 0.006%, and Fe as the balance.

[0008] Step S2: Prepare impurity raw materials, the components of which include: silicon oxide, aluminum oxide and magnesium oxide; calculate the mass ratio of the alloy raw material and the impurity raw material according to the target dirty white spot impurity content requirement; Step S3: Use induction melting technology to heat and melt the alloy raw material and the impurity raw material in a vacuum environment, so that the impurity raw material is dispersed in the molten metal.

[0009] Step S4: Pour the molten metal obtained in step S3 into a mold to form a dirty white spot ingot. Preferably, in the alloy raw material element ratio, the Nb content is ≤4%.

[0010] Preferably, the impurity raw material specifically includes: magnesium oxide and mullite powder; the mass ratio of magnesium oxide and mullite is 1:1.

[0011] Preferably, the impurity content of the target dirty white spot is required to be 0.05% to 3%.

[0012] Preferably, the mass ratio of the alloy raw material and the impurity raw material is calculated using the following formula:

[0013] The mass fraction w of the target dirty white spot impurity is:

[0014]

[0015] Mass of dirty white spots m = Mass of alloy raw material m1 + Mass of impurities m2

[0016] m1:m2=(1-w):w

[0017] Where m1:m2 is the mass ratio of alloy raw materials to impurity raw materials.

[0018] Preferably, step S3 specifically includes:

[0019] Before smelting, the bottom of the crucible containing Ni, Fe, C, Mo, Cr, and Nb is loaded, and the vacuum is drawn to less than 7 Pa. The power is increased to 90-100 kW for melting.

[0020] The refining process was carried out at a power of 10 kW, a temperature of 1520 ± 10 ℃, and a time of 5 min, after which the power was turned off and the film was formed.

[0021] During the film-making process, Al, Ti, and B are loaded onto the substrate. After Al, Ti, and B are melted, the impurity raw material powder is loaded onto the substrate.

[0022] Preferably, step S4 specifically includes:

[0023] Keep the induction furnace powered on and pour the molten metal into the mold after melting. The process parameters for the electric casting are: casting temperature 1420±10℃ and casting speed 30-50s. After the molten metal solidifies, a dirty white spot ingot is obtained.

[0024] Preferably, the ingot produced by melting in step S4 weighs 4-5 kg, has a diameter of 75-85 mm, and a height of 110-130 mm.

[0025] This invention is used to prepare blemish-white defects in deformed high-temperature alloys with controllable solute elements, thereby increasing the content of non-metallic impurities. This provides a material basis for subsequent research on defect attribute detection and non-destructive testing capabilities, and provides a theoretical and material basis for the safety assessment of life-limited deformed high-temperature alloy components for aero-engines.

[0026] Compared with the prior art, the present invention has at least the following beneficial effects:

[0027] (1) The method provided by the present invention can control the Nb content and produce dirty white material with controllable composition;

[0028] (2) The method provided by the present invention increases the content of non-metallic impurities in metal ingots and the types of impurities are controllable;

[0029] (3) The method provided by the present invention can provide materials with a volume and mass much larger than those produced in industrial production, which facilitates the testing of various properties of defects. Attached Figure Description

[0030] The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention.

[0031] Figure 1 This is a flowchart of a method for preparing GH4169 alloy dirty white spot material using induction melting, provided in an embodiment of the present invention.

[0032] Figure 2 A flowchart of a method for preparing GH4169 alloy dirty white spot material using induction melting, provided in another embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of a casting ingot containing dirty white spots after casting, provided in an embodiment of the present invention.

[0034] Figure 4 This is a schematic diagram of the analysis results of impurity components in a certain natural dirty white spot provided by the present invention;

[0035] Figure 5 A metallographic microstructure of artificially prepared Nb content 4 wt% and impurity content 0.05 wt% with white spots, provided for an embodiment of the present invention;

[0036] Figure 6 The image shows a metallographic microstructure of a dirty white spot with a Nb content of 4wt% and an impurity content of 3wt%, prepared artificially for an embodiment of the present invention. Detailed Implementation

[0037] To better understand the above-described objectives, features, and advantages of the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other. Furthermore, the present invention can be implemented in other ways different from those described herein; therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0038] The design concept of this invention is as follows: Based on the characteristics that the Nb content of natural dirty white spots is lower than that of the matrix GH4169 material and contains non-metallic impurities, in the raw material preparation, the Nb element is artificially reduced and non-metallic impurity particles are added based on the elemental composition of GH4169. Artificial dirty white spot materials with the defect characteristics of natural dirty white spots are prepared by induction melting process.

[0039] Example 1

[0040] One specific embodiment of the present invention is as follows: Figure 2 As shown, a method for preparing GH4169 alloy dirty white spot material using induction melting is disclosed, including the following steps:

[0041] (1) Based on the target GH4169 composition, reduce the Nb content to below the standard range, fill the reduced element mass with Fe, and keep other elements within the standard range to prepare alloy raw materials;

[0042] (2) Determine the types of impurities to be added to the target dirty white spot, calculate the mass ratio of alloy raw materials and impurity raw materials according to the impurity content requirements of the target dirty white spot, and prepare the impurity raw materials;

[0043] (3) Using induction melting technology, the white spot component material is heated and melted in a vacuum environment, while the impurity raw materials are dispersed in the molten metal;

[0044] (4) Pour the molten metal obtained in step (3) into the mold to form dirty white spot casting material.

[0045] In some embodiments, in step (1) above, the alloy element content ratio is calculated by the following method:

[0046] Based on the target GH4169 composition, the Nb content is reduced to below the standard range, while the Ni, C, Mo, Cr, Al, Ti, and B elements remain unchanged, and the rest are Fe.

[0047] In some embodiments, in step (2) above: determining the type of added impurities should refer to the analysis results of natural dirty white spots.

[0048] In some embodiments, in step (2) above, the mass ratio of alloy raw materials and impurity raw materials is calculated using the following formula:

[0049] The mass fraction w of the target dirty white spot impurity is:

[0050]

[0051] in:

[0052] Mass of dirty white spots m = Mass of alloy raw material m1 + Mass of impurities m2

[0053] The mass ratio of alloy raw materials to impurity raw materials can be calculated as follows:

[0054] m1:m2=(1-w):w

[0055] After determining the mass fraction of impurities based on research needs, the ratio of the mass of alloy raw materials to the mass of impurity raw materials can be calculated using the above formula.

[0056] In some embodiments, in step (3) above, the loading method is as follows: before melting, Ni, Fe, C, Mo, Cr and Nb crucible bottom is loaded; during film forming, Al, Ti and B are loaded; after Al, Ti and B are melted, impurity raw materials are loaded.

[0057] In some embodiments, in step (3) above, the induction melting parameters are: vacuum degree less than 7 Pa, refining power of 10 kW, temperature of 1520 ± 10 ° C, and time of 5 min.

[0058] In some embodiments, the process parameters for casting the ingot in step (4) above are: casting temperature 1420±10℃, casting speed 30-50s.

[0059] The dirty white spot material prepared by the preparation method described in the embodiments of the present invention has a Nb content lower than the normal range of the target GH4169 in terms of elemental composition; non-metallic impurities can be observed in the microstructure observation image.

[0060] Based on the above technical solution, this invention achieves control over the element ratio in the alloy by adjusting the Nb content in the alloy raw material to below the standard range and filling the reduced element mass with Fe, thereby meeting the requirement of producing controllable dirty white spot materials in research or application; the optimization of the charging method helps to achieve uniformity of material composition and control of impurity distribution; through precise material proportioning and process control, the preparation of dirty white spot materials of GH4169 alloy is realized, which provides raw material support for testing various properties of defects in industrial applications.

[0061] Example 2

[0062] Another embodiment of the invention is as follows: Figure 1 As shown, a method for preparing GH4169 alloy dirty white spot material using induction melting is disclosed, including the following steps:

[0063] (1) Determine the Nb content of the target dirty white spot based on the elemental distribution of the target GH4169 and proportion the metal raw materials accordingly;

[0064] (2) Determine the types of impurities added to the target dirty white spot and formulate the impurity raw materials accordingly;

[0065] (3) The raw materials are smelted and processed using induction melting technology;

[0066] (4) Pour the molten metal into the mold to form dirty white spot casting material.

[0067] The specific steps include:

[0068] Step S1: Prepare alloy raw materials. The composition ratio of the alloy raw materials is: Nb < 5%, C 0.015-0.06%, Cr 17-21%, Ni 50-55%, Mo 2.8-3.3%, Al 0.3-0.7%, Ti 0.75-1.15%, B ≤ 0.006%, and Fe as the balance.

[0069] Step S2: Prepare impurity raw materials, the components of which include: silicon oxide, aluminum oxide and magnesium oxide; calculate the mass ratio of the alloy raw materials to the impurity raw materials according to the target dirty white spot impurity content requirements;

[0070] Step S3: Using induction melting technology, the alloy raw material and the impurity raw material are heated and melted in a vacuum environment, so that the impurity raw material is dispersed in the molten metal.

[0071] Step S4: Pour the molten metal obtained in step S3 into a mold to form a dirty white spot ingot material.

[0072] The steps in this embodiment will be explained in detail below through specific experimental examples:

[0073] Using a vacuum induction furnace, the smelted ingots weigh 4-5 kg, have a diameter of approximately 75-85 mm, and a height of 110-130 mm. Figure 3 As shown.

[0074] In some embodiments, the Nb content in the alloy raw material composition is ≤4%.

[0075] This embodiment prepares a dirty white spot material with a Nb content of 4% and an impurity content of 0.05%, including the following steps:

[0076] 1) The elemental distribution of the target GH4169 is shown in the table below:

[0077]

[0078] Based on the elemental distribution of the target GH4169, the Nb content was reduced to below the specified range. In this embodiment, the Nb content of the dirty white spots was determined to be 4%. Other elements: C-0.025, B-0.004, Nb-4.0, Mo-3.0, Al-0.5, Cr-18, Ti-1.0, Ni-53 were all within the standard range, and the remainder was Fe. Alloy raw materials were prepared according to the above element mass ratios.

[0079] 2) Based on the analysis of a certain natural blemish-white spot, such as Figure 4 As shown, the impurities include silicon oxide, aluminum oxide and magnesium oxide. Therefore, magnesium oxide and mullite powder were selected as the impurity additives, with a mass ratio of magnesium oxide to mullite of 1:1.

[0080] In some implementations, the target impurity content for dirty white spots is required to be 0.05% to 3%.

[0081] In some implementations, the mass ratio of the alloy raw material and the impurity raw material is calculated using the following formula:

[0082] The mass fraction w of impurities in the target dirty white spot is:

[0083]

[0084] Mass of dirty white spots m = Mass of alloy raw material m1 + Mass of impurities m2

[0085] m1:m2=(1-w):w

[0086] Where m1:m2 is the mass ratio of alloy raw materials to impurity raw materials.

[0087] In this embodiment, the target impurity content of dirty white spots is 0.05%, and the calculated mass ratio of alloy raw material to impurity raw material is 99.95:0.05.

[0088] 3) Load Ni, Fe, C, Mo, Cr and Nb, evacuate to less than 7 Pa, increase power to 90-100 kW for refining, power at 10 kW, temperature at 1520±10℃, time at 5 min, power off for film formation, load Al, Ti and B during film blasting, load impurity powder raw materials during refining.

[0089] 4) Keep the induction furnace powered on and pour the molten metal into the mold after melting. The electric casting process parameters are: casting temperature 1420±10℃, casting speed 30-50s. After the molten metal solidifies, a dirty white spot ingot is obtained.

[0090] Figure 5 The figure shows the microstructure of the dirty white spot material prepared in this example. As can be seen from the figure, the dirty white spot material prepared in this example has a dense structure and contains non-metallic oxides. In addition, according to the results of the chemical composition test of the sample, the Nb content of the ingot material is 3.98wt%, which is lower than the normal range of the target GH4169 and has the typical characteristics of dirty white spots.

[0091] Example 3

[0092] This embodiment uses the same vacuum induction furnace as Embodiment 2. The smelted ingot weighs 4-5 kg, has a diameter of about 75-85 mm, and a height of 110-130 mm.

[0093] This embodiment prepares a dirty white spot material with a Nb content of 4% and an impurity content of 3%, including the following steps:

[0094] 1) The elemental distribution of the target GH4169 is shown in the table below:

[0095]

[0096] Based on the elemental distribution of the target GH4169, the Nb content was reduced to below the specified range. In this example, the Nb content of the dirty white spots was determined to be 4%. Other elements: C-0.025, B-0.004, Nb-4.0, Mo-3.0, Al-0.5, Cr-18, Ti-1.0, Ni-53 were all within the standard range, and the remainder was Fe. Alloy raw materials were prepared according to the above element mass ratios.

[0097] 2) Based on the analysis of a certain natural blemish-white spot, such as Figure 4 As shown, the impurities include silicon oxide, aluminum oxide, and magnesium oxide. Therefore, magnesium oxide and mullite powder were selected as the impurity additives, with a mass ratio of magnesium oxide to mullite of 1:1. In this embodiment, the target dirty white spot impurity content is 3%, and the calculated mass ratio of alloy raw material to impurity raw material is 97:3.

[0098] 3) Load Ni, Fe, C, Mo, Cr and Nb, evacuate to less than 7 Pa, increase power to 90-100 kW for refining, power at 10 kW, temperature at 1520±10℃, time at 5 min, power off for film formation, load Al, Ti and B during film blasting, load impurity powder raw materials during refining.

[0099] 4) Keep the induction furnace powered on and pour the molten metal into the mold after melting. The electric casting process parameters are: casting temperature 1420±10℃, casting speed 30-50s. After the molten metal solidifies, a dirty white spot ingot is obtained.

[0100] Figure 6The image shows the microstructure of the dirty white spot material prepared in this example. As can be seen from the image, the dirty white spot material prepared in this example has a dense structure and contains non-metallic oxides. Furthermore, according to the results of the chemical composition testing, the Nb content of the ingot material is 4.24 wt%, which is lower than the normal range for the target GH4169, exhibiting typical characteristics of dirty white spots.

[0101] While the specific embodiments of the present invention depict actions or steps in a particular order, this should be understood as requiring such actions or steps to be performed in the specific order shown or in sequential order, or requiring all illustrated actions or steps to be performed to achieve the desired result. In certain environments, multitasking and parallel processing may be advantageous. Similarly, although several specific implementation details are included in the above discussion, these should not be construed as limiting the scope of this disclosure. Certain features described in the context of individual embodiments may also be implemented in combination in a single implementation. Conversely, various features described in the context of a single implementation may also be implemented individually or in any suitable sub-combination in multiple implementations.

[0102] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing GH4169 alloy dirty white spot material using induction melting, characterized in that, Includes the following steps: Step S1: Prepare alloy raw materials. The element ratio of the alloy raw materials is as follows: Nb < 5%, C 0.015-0.06%, Cr 17-21%, Ni 50-55%, Mo 2.8-3.3%, Al 0.3-0.7%, Ti 0.75-1.15%, B ≤ 0.006%, and Fe as the balance. Step S2: Prepare impurity raw materials, the components of which include: silicon oxide, aluminum oxide and magnesium oxide; calculate the mass ratio of the alloy raw materials to the impurity raw materials according to the target dirty white spot impurity content requirements; Step S3: Using induction melting technology, the alloy raw material and the impurity raw material are heated and melted in a vacuum environment, so that the impurity raw material is dispersed in the molten metal. Step S4: Pour the molten metal obtained in step S3 into a mold to form a dirty white spot ingot material.

2. The method for preparing GH4169 alloy dirty white spot material by induction melting according to claim 1, characterized in that: In the alloy raw material element ratio, the Nb content is ≤4%.

3. The method for preparing GH4169 alloy dirty white spot material by induction melting according to claim 1, characterized in that: The specific components of the impurity raw materials include: magnesium oxide and mullite powder; the mass ratio of magnesium oxide to mullite is 1:

1.

4. The method for preparing GH4169 alloy dirty white spot material by induction melting according to claim 1, characterized in that: The required impurity content of the target dirty white spots is greater than 0.05%.

5. The method for preparing GH4169 alloy dirty white spot material by induction melting according to claim 4, characterized in that: The mass ratio of the alloy raw material and the impurity raw material is calculated using the following formula: The mass fraction w of the target dirty white spot impurity is: Mass of dirty white spots m = Mass of alloy raw material m1 + Mass of impurities m2 m1:m2=(1-w):w Where m1:m2 is the mass ratio of alloy raw materials to impurity raw materials.

6. The method for preparing GH4169 alloy dirty white spot material by induction melting according to claim 1, characterized in that: Step S3 specifically includes: Before smelting, the bottom of the crucible containing Ni, Fe, C, Mo, Cr, and Nb is loaded, the vacuum is drawn to less than 7 Pa, and the power is increased to 90-100 kW for melting. The refining process was carried out at a power of 10 kW, a temperature of 1520 ± 10 ℃, and a time of 5 min, after which the power was turned off and the film was formed. During the film-making process, Al, Ti, and B are loaded onto the substrate. After Al, Ti, and B are melted, the impurity raw material powder is loaded onto the substrate.

7. The method for preparing GH4169 alloy dirty white spot material by induction melting according to claim 1, characterized in that: Step S4 specifically includes: Keep the induction furnace powered on and pour the molten metal into the mold after melting. The process parameters for the electric casting are: casting temperature 1420±10℃ and casting speed 30-50s. After the molten metal solidifies, a dirty white spot ingot is obtained.

8. The method for preparing GH4169 alloy dirty white spot material by induction melting according to claim 7, characterized in that: The ingot produced by melting in step S4 weighs 4-5 kg, has a diameter of 75-85 mm, and a height of 110-130 mm.

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