CN112746182B - Method for promoting electron beam refining nickel-based high-temperature alloy desulfurization by adding desulfurizer - Google Patents

Method for promoting electron beam refining nickel-based high-temperature alloy desulfurization by adding desulfurizer Download PDF

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CN112746182B
CN112746182B CN202011583239.8A CN202011583239A CN112746182B CN 112746182 B CN112746182 B CN 112746182B CN 202011583239 A CN202011583239 A CN 202011583239A CN 112746182 B CN112746182 B CN 112746182B
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electron beam
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CN112746182A (en
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谭毅
李毅
游小刚
李鹏廷
王轶农
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Dalian University of Technology
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    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
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    • C22B9/22—Remelting metals with heating by wave energy or particle radiation
    • C22B9/228—Remelting metals with heating by wave energy or particle radiation by particle radiation, e.g. electron beams
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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    • C22C1/00—Making non-ferrous alloys
    • C22C1/02—Making non-ferrous alloys by melting
    • C22C1/023—Alloys based on nickel
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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    • C22C1/00—Making non-ferrous alloys
    • C22C1/02—Making non-ferrous alloys by melting
    • C22C1/03—Making non-ferrous alloys by melting using master alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/06—Making non-ferrous alloys with the use of special agents for refining or deoxidising
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Abstract

The invention provides a method for promoting electron beam refining nickel-based superalloy desulfurization by adding a desulfurizing agent, which comprises the following steps: s1, preprocessing a high-temperature alloy raw material; and S2, refining and purifying the high-temperature alloy by using an electron beam to obtain a high-purity FGH4096 high-temperature alloy cast ingot. According to the invention, trace Ca element is added as a desulfurizer before electron beam refining of the nickel-based superalloy, so that the deep removal of S impurities in the process of electron beam refining of the nickel-based superalloy is promoted, and the problem of ultra-pure purification of the nickel-based superalloy base metal is solved.

Description

Method for promoting electron beam refining nickel-based high-temperature alloy desulfurization by adding desulfurizer
Technical Field
The invention relates to a method for promoting electron beam refining nickel-based high-temperature alloy desulfurization by adding a desulfurizing agent.
Background
The high-temperature alloy material is widely applied to the fields of aerospace and the like, and is an important material for manufacturing hot end parts in the field of aerospace. Because the material is in extreme working environments of high temperature, high rotating speed, high stress and the like for a long time, the material has extremely high requirements on high-temperature strength, creep deformation and fatigue performance, and the research and application level of the material is an important mark for measuring the comprehensive strength of national material science. And S impurity elements in the high-temperature alloy are easy to form low-melting-point eutectic, so that the plasticity of the material is reduced, segregation is easy to occur, and the sensitivity of crystal cracks is increased. Therefore, the control and reduction of the content of the S element are key to solve the problem of ultra-pure purification of the high-temperature alloy parent metal.
For the desulfurization of nickel-based superalloys, a generally feasible method is to melt the alloy by vacuum induction melting. At present, the mature vacuum induction melting technology in China can reduce the sulfur content in the alloy to about 10ppmw, the desulfurization effect is not obvious when the vacuum induction melting technology is used alone, and desulfurization is carried out by adding a desulfurizing agent in a matching way, namely, some desulfurizing agents with high affinity with sulfur are selected and used, and the desulfurizing agents can be generatedThe metallic element of the sulfide with high melting point and low density and easy floating is used as a desulfurizer. However, inclusions such as CaS and calcium aluminate, which are final products of desulfurization by means of the vacuum induction melting technology, can be removed only by means of floatation, and the method has a very limited effect on removal of small-sized inclusions, thereby having an adverse effect on high-purity production of the high-temperature alloy. In recent years, researches show that the effects of CaO crucible desulfurization and slag desulfurization are very obvious, but the calcium oxide crucible has short service life, high cost and great production difficulty, and the desulfurization effect is greatly reduced after a plurality of times of use, so that the industrial production is still unacceptable at present. In addition, a CaO crucible is adopted to smelt the high-temperature alloy, the desulfurization reaction is carried out at the interface between the crucible wall and the metal melt, and the generated 3CaO & Al2O3Although the low-melting-point slag is beneficial to deep deoxidation and desulfurization, the problem of corrosion of crucible refractory materials is serious, and the desulfurization products are difficult to remove, so that the preparation of the high-purity nickel-based high-temperature alloy is not facilitated.
Disclosure of Invention
According to the method, the effects of CaO crucible desulfurization and slag desulfurization are obvious, but the calcium oxide crucible has short service life, high cost and high production difficulty, and the desulfurization effect is greatly reduced after a plurality of times of use, so that the industrial production is not acceptable at present. In addition, a CaO crucible is adopted to smelt the high-temperature alloy, the desulfurization reaction is carried out at the interface between the crucible wall and the metal melt, and the generated 3CaO & Al2O3The low-melting-point slag is beneficial to deep deoxidation and desulfurization, but the problems of serious corrosion of crucible refractory materials, difficult removal of desulfurization products and inconvenience for the preparation of the high-purity nickel-based high-temperature alloy are solved, and the method for promoting the desulfurization of the electron beam refined nickel-based high-temperature alloy by adding the desulfurizer is provided. The method mainly utilizes the trace Ca element added before electron beam refining of the nickel-based superalloy as a desulfurizer to promote the deep removal of S impurities in the process of electron beam refining of the nickel-based superalloy and solve the problem of ultra-pure purification of the nickel-based superalloy base metal.
The technical means adopted by the invention are as follows:
a method for promoting electron beam refining nickel-based superalloy desulfurization by adding a desulfurizing agent comprises the following steps:
s1, pretreatment of the high-temperature alloy raw material:
s11, the raw material is FGH4096 master alloy prepared by vacuum induction melting;
s12, cutting the raw material into blocks with the length of 50mm, the width of 20mm and the height of 20mm on an online cutting lathe so as to be placed in a water-cooled copper crucible;
s13, grinding the surface of the cut raw material by using a grinder, and removing oxide skin and oil contamination impurities on the surface to ensure that the surface of the raw material is bright and clean;
s14, placing the polished raw materials in an ultrasonic cleaning machine, and respectively carrying out ultrasonic cleaning on the raw materials by using deionized water and alcohol for three times;
s15, after ultrasonic cleaning, putting the cleaned raw material into a beaker of a drying oven to prevent dust and other impurities from adhering, drying for 10min at the temperature of 80 ℃ until electron beams are refined for use;
s2, refining and purifying the high-temperature alloy by using an electron beam:
s21, cleaning the water-cooled copper crucible, the electron beam melting furnace body and the furnace wall;
s22, placing a calcium metal desulfurizer at the bottom of the water-cooled copper crucible, placing the pretreated raw material on the upper part of the calcium metal desulfurizer, preventing loss caused by bombardment volatilization of the calcium desulfurizer when an electron beam starts to heat and melt, promoting the calcium desulfurizer and an alloy melt to be fully mixed and react, and closing a furnace door for refining after the calcium metal desulfurizer is determined to be ready and a furnace body is cleaned;
s23, carrying out vacuum pre-pumping on the melting chamber and the electron gun chamber of the electron beam melting furnace to reach the target vacuum degree; preheating the electron gun after the target vacuum degree is reached;
s24, after preheating is finished, smelting the raw materials by an electron beam annular scanning path;
s25, observing whether the alloy is molten or not, and after the raw materials and the elemental calcium are completely molten and mixed in the water-cooled copper crucible, refining the raw materials for 20min to enable the elemental calcium in the high-temperature alloy melt to fully react with sulfur impurities;
s26, after the refining process is finished, controlling electron beam refining parameters to enable inclusions in the alloy to migrate to the edge of the upper surface of the ingot;
s27, turning off the high voltage of the electron gun, increasing the beam current to 60mA, and turning off the power supply of the electron gun after the high voltage value is reduced to 0kV, so that the cast ingot is fully solidified in the water-cooled copper crucible and cooled for 2 hours;
s28, taking out the electron beam refined FGH4096 alloy cast ingot after the furnace body and the cast ingot are cooled, and cutting off the impurity-enriched part of the final solidification region on the surface of the cast ingot to obtain the high-purity FGH4096 high-temperature alloy cast ingot.
Further, the specific steps of step S21 are as follows:
firstly, grinding and polishing the water-cooled copper crucible by using No. 1000 abrasive paper, then wiping the water-cooled copper crucible by using cotton cloth stained with alcohol, and drying the alcohol by using a blower after ensuring that the water-cooled copper crucible is clean and pollution-free, so as to ensure that the crucible is kept dry;
800# abrasive paper and a brush are used for cleaning pollutants on the furnace body and the furnace wall of the electron beam smelting furnace, the carbon felt covers the position which is easy to splash around the crucible, and the damage of alloy molten drop splashing to equipment in the electron beam refining process is prevented.
Further, in the step S22, the content of the calcium metal desulfurizing agent is 0.15 wt.%.
Further, the specific steps of step S23 are as follows:
connecting cooling water, air compressor, and power supply of electron beam refining equipment, determining that water-cooling devices of electron beam melting furnace have no water leakage, vacuumizing the melting chamber and electron gun chamber of electron beam melting furnace to target vacuum state, wherein the vacuum degree of electron gun chamber is required to be less than 5 × 10-3Pa, the vacuum degree of the smelting chamber is required to be less than 5 multiplied by 10-2Pa；
After the smelting chamber and the electron gun chamber reach the target vacuum degree, starting the electron gun, slowly adjusting the beam current to 120mA, and preheating for 12 minutes.
Further, the specific steps of step S24 are as follows:
and (3) immediately adjusting the beam current of the electron gun to 0 after preheating is finished, starting high voltage, slowly increasing the beam current of the electron gun to 450mA after the high voltage reaches 30kV and is stabilized for 1min, adjusting the radius of a beam spot to 20mm, keeping the parameters of the electron gun unchanged, and smelting the FGH4096 master alloy in an annular scanning path.
Further, the specific steps of step S25 are as follows:
observing whether the alloy is molten or not from an observation window, after the FGH4096 alloy and the metal calcium simple substance in the water-cooled copper crucible are completely molten and mixed, slowly reducing the beam current to 350mA at the speed of 30mA/min, continuously maintaining the parameters, and refining the FGH4096 mother alloy for 20min by using an electron beam annular scanning path, so that the metal calcium element in the high-temperature alloy melt and sulfur impurities fully react to generate desulfurization products such as calcium sulfide inclusion and the like, the desulfurization products are promoted to float up to the surface of the melt under the action of buoyancy and the Marangoni effect, the desulfurization products below the melt liquid level are dissolved under the local overheating condition of the melt, the desulfurization products above the melt liquid level are decomposed under the action of electron beam bombardment, and meanwhile, the volatile sulfur impurities are fully removed in the vacuum degassing reaction.
Compared with the prior art, the invention has the following advantages:
1. the invention provides a method for promoting desulfurization of electron beam refining nickel-based superalloy by adding a desulfurizing agent, and innovatively provides a method for promoting deep removal of S impurities in the process of electron beam refining nickel-based superalloy by adding trace Ca element as a desulfurizing agent before electron beam refining nickel-based superalloy. The desulfurizing method of the desulfurizing agent is combined with the electron beam refining technology, aiming at the characteristic that the electron beam slowly falls down and can induce and enrich the impurities, the desulfurizing efficiency of electron beam refining nickel-based high-temperature alloy is further improved by adding a trace amount of calcium desulfurizing agent; aiming at the problem of corrosion of refractory materials of the crucible, a pollution-free water-cooled copper crucible is adopted to improve the purity of the alloy; aiming at the problem that the final product of the vacuum induction melting technology for desulfurization is difficult to remove, the electron beam induced solidification technology is utilized to carry out induced removal on S-containing inclusions and desulfurization products, so that the S impurity content is further reduced, and the method has important significance for reducing the manufacturing cost of the high-temperature alloy in China and promoting the high-purification production of the high-temperature alloy in China.
2. According to the method for promoting the desulfurization of the electron beam refined nickel-based superalloy by adding the desulfurizer, S impurities and inclusions in the nickel-based superalloy are fully removed through the electron beam refined superalloy, and the evaporation removal of S impurity elements is enhanced by utilizing the characteristics of high vacuum degree and high temperature of a beam spot area in the electron beam refined superalloy; the problem of corrosion of refractory materials of the crucible is solved by utilizing the characteristic of no pollution of the water-cooled copper crucible in the refining process; by utilizing the revolutionary technology of electron beam induced solidification, the floating and aggregation of the inclusions in the smelting process are promoted according to the density difference of the inclusions and the melt and the Marangoni effect, the problem that the migration and removal mechanism of desulfurization products and inclusions containing S is single after desulfurization is solved, and the content of the S impurities in the high-temperature alloy is comprehensively reduced by combining the characteristics.
3. According to the method for promoting the desulfurization of the electron beam refining nickel-based superalloy by adding the desulfurizer, the S impurity content of the prepared FGH4096 superalloy cast ingot is less than 5ppm and lower than that of the superalloy prepared by the traditional process, and a new method is provided for the high-purity production of the superalloy.
In conclusion, the technical scheme of the invention can solve the problems that the desulfuration by adopting the CaO crucible and the desulfuration by the molten slag in the prior art have obvious effects, but the calcium oxide crucible has short service life, high cost and large production difficulty, and the desulfuration effect is greatly reduced after being used for a plurality of times, so that the industrial production is not acceptable at present. In addition, a CaO crucible is adopted to smelt the high-temperature alloy, the desulfurization reaction is carried out at the interface between the crucible wall and the metal melt, and the generated 3CaO & Al2O3Although the low-melting-point slag is beneficial to deep deoxidation and desulfurization, the problem of serious corrosion of crucible refractory materials, difficulty in removing desulfurization products and inconvenience in preparation of the high-purity nickel-based high-temperature alloy are solved.
Based on the reasons, the invention can be widely popularized in the fields of aerospace, industrial gas turbines and the like.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a schematic diagram of the process of removing sulfur-containing inclusions and volatilizing impurity elements in a melt by electron beam refining according to the present invention.
FIG. 2 is a schematic diagram of inclusion enrichment in the last solidification zone of the present invention.
In the figure: 1. an electron gun; 2. an oil diffusion pump; 3. a valve; 4. a mechanical pump; 5. an electron beam; 6. desulfurization products; 7. a roots pump; 8. an alloy molten pool; 9. water-cooling the copper crucible; 10. cooling water; 11. and an inclusion induction enrichment area.
Detailed Description
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
The relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. Any specific values in all examples shown and discussed herein are to be construed as exemplary only and not as limiting. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.
The high-temperature alloy is an important high-temperature structural material required by key hot-end components (such as turbine blades, turbine discs, combustion chambers and the like) of modern aeroengines, industrial gas turbines and the like, trace impurity elements in the alloy have great influence on the performance of the high-temperature alloy, and S is one of main impurity elements. As S impurities are easy to be segregated at the crystal boundary or phase boundary of the nickel-based high-temperature alloy and become channels for generating and expanding cracks, the high-temperature endurance life and the use stability of the alloy are reduced, and the tensile plasticity of the alloy is obviously reduced along with the increase of the S content. Therefore, the method has important significance for deeply removing the S element in the nickel-based superalloy. Ca element has low solid solubility in nickel-based superalloy, but has large affinity with elements such as S, O and the like, and calcium compounds such as CaS and CaO are easily generated, so Ca is often used as a purifying agent in the process of refining superalloy. In addition, in the nickel-base high-temperature alloy containing Al2O3 inclusions, CaO as a deoxidation product is easy to combine with the nickel-base high-temperature alloy to generate calcium aluminate slag, which further absorbs S impurities in the alloy melt. The desulfurization products such as CaS, calcium aluminate and the like which are desulfurized by using Ca element have low density and large interfacial tension with a high-temperature alloy melt under general conditions, so the desulfurization products are easy to float, enrich and remove in the process of electron beam slow beam falling induced solidification. By combining the above mechanisms, the invention considers the characteristic of low Ca content in the nickel-based superalloy FGH4096, and innovatively provides that trace Ca element is added as a desulfurizer before electron beam refining of the nickel-based superalloy, so that the deep removal of S impurities in the process of electron beam refining of the nickel-based superalloy is promoted, and the problem of ultra-pure purification of the nickel-based superalloy base metal is solved.
As shown in the figure, the invention provides a method for promoting electron beam refining nickel-based superalloy desulfurization by adding a desulfurizing agent, which comprises the following steps:
pretreatment of high-temperature alloy raw materials
1. The FGH4096 master alloy prepared by vacuum induction melting is selected as a raw material for electron beam refining desulphurization, and the FGH4096 master alloy is cut into small blocks with the length of 50mm, the width of 20mm and the height of 20mm on an online cutting lathe so as to be put into a water-cooled copper crucible.
2. And (3) polishing the cut master alloy surface by using a grinding machine, and removing impurities such as oxide skin, oil stains and the like on the surface, so that the master alloy surface is bright and clean.
3. And (3) placing the polished FGH4096 master alloy small blocks in an ultrasonic cleaning machine, and respectively carrying out ultrasonic cleaning on the FGH4096 master alloy small blocks by using deionized water and alcohol for three times.
4. And after the ultrasonic cleaning is finished, placing the glass into a beaker of a drying oven to prevent dust and other impurities from adhering, drying the glass at the temperature of 80 ℃ for 10min, and waiting for electron beam refining.
Second, refining and purifying high-temperature alloy by electron beam
1. Firstly, 1000# abrasive paper is used for polishing the water-cooled copper crucible, then the cotton cloth stained with alcohol is used for wiping the water-cooled copper crucible, after the water-cooled copper crucible is clean and pollution-free, the alcohol is dried by a blower, and the crucible is ensured to be kept dry.
2. 800# abrasive paper and a brush are used for cleaning pollutants on the furnace body and the furnace wall of the electron beam smelting furnace, the carbon felt covers the position which is easy to splash around the crucible, and the damage of alloy molten drop splashing to equipment in the electron beam refining process is prevented.
3. The calcium metal desulfurizer with the content of 0.15 wt.% is placed at the bottom of a water-cooled copper crucible (calcium is used as the desulfurizer, and the calcium can achieve the effect of deep desulfurization), and then the pretreated FGH4096 master alloy is placed at the upper part of the calcium metal desulfurizer, so that the loss caused by bombardment volatilization of the calcium desulfurizer when an electron beam starts to be heated and melted is prevented, the calcium desulfurizer and an alloy melt are fully mixed and react, the preparation is determined, and a furnace door is closed after a furnace body is cleaned and is ready for refining.
4. Connecting cooling water, air compressor, and power supply of electron beam refining equipment, determining that water-cooling devices of electron beam melting furnace have no water leakage, vacuumizing the melting chamber and electron gun chamber of electron beam melting furnace to target vacuum state, wherein the vacuum degree of electron gun chamber is required to be less than 5 × 10-3Pa, the vacuum degree of the smelting chamber is required to be less than 5 multiplied by 10-2Pa。
5. After the smelting chamber and the electron gun chamber reach the target vacuum degree, starting the electron gun, slowly adjusting the beam current to 120mA, and preheating for 12 minutes.
6. And (3) immediately adjusting the beam current of the electron gun to 0 after preheating is finished, starting high voltage, slowly increasing the beam current of the electron gun to 450mA after the high voltage reaches 30kV and is stabilized for 1min, adjusting the radius of a beam spot to 20mm, keeping the parameters of the electron gun unchanged, and smelting the FGH4096 master alloy in an annular scanning path.
7. Observing whether the alloy is molten or not from an observation window, after the FGH4096 alloy and the metal calcium simple substance in the water-cooled copper crucible are completely molten and mixed, slowly reducing the beam current to 350mA at the speed of 30mA/min, continuously maintaining the parameters, and refining the FGH4096 mother alloy for 20min by using an electron beam annular scanning path, so that the metal calcium element in the high-temperature alloy melt and the sulfur impurities fully react to generate desulfurization products such as calcium sulfide inclusion and the like, the desulfurization products are promoted to float up to the surface of the melt under the action of buoyancy and the Marangoni effect, the desulfurization products below the melt liquid level are dissolved under the local overheating condition of the melt, the desulfurization products above the melt liquid level are decomposed under the action of electron beam bombardment, and meanwhile, the volatile sulfur impurities are fully removed in the vacuum degassing reaction (figure 1).
8. After the refining process is finished, controlling the refining parameters of the electron beam to enable the beam spot of the electron beam to move slowly from left to right, and gradually reducing the size of the beam to 0mA at a speed of 70mA/min in the moving process of the beam spot so that impurities in the alloy are moved to the edge of the upper surface of the cast ingot (figure 2).
9. And (3) closing the high voltage of the electron gun, increasing the beam current to 60mA, and closing the power supply of the electron gun after the high voltage value is reduced to 0kV, so that the cast ingot is fully solidified in the water-cooled copper crucible and cooled for 2 hours.
10. And cooling the furnace body and the cast ingot, taking out the FGH4096 alloy cast ingot refined by the electron beam, and cutting off the impurity-enriched part in the final solidification region on the surface of the cast ingot so as to obtain the high-purity FGH4096 high-temperature alloy cast ingot.
FIG. 1 is a schematic diagram showing the electron beam melting process for dissolving small-sized inclusions in a melt by overheating and the volatilization process of impurity elements, and FIG. 2 is a schematic diagram showing the enrichment of inclusions in the final solidification zone. The invention adopts the equipment shown in figures 1 and 2 to carry out the desulfurization process of the high-temperature alloy. The electron gun 1 is fixed at the top side corner of the electron beam melting furnace, the water-cooled copper crucible 9 is placed at the bottom of the electron beam melting furnace, and cooling water 10 is introduced. The metallic calcium desulfurizer is placed in a water-cooled copper crucible 9, and the pretreated FGH4096 alloy block 5 is placed on the upper part of the metallic calcium desulfurizer and is within the scanning range of the electron beam 5. The oil diffusion pump 2 is adjacent to the mechanical pump 4, and the communication relationship between the oil diffusion pump and the mechanical pump is controlled by a valve 3; the roots pump 7 is adjacent to the furnace body mechanical pump 4, and the two are connected together. After the raw materials are melted, an alloy molten pool 8 is formed in a water-cooled copper crucible 9, metallic calcium in the high-temperature alloy molten pool and sulfur impurities fully react to generate desulfurization products 6 such as calcium sulfide inclusion and the like, and after the refining process is finished, an inclusion induction enrichment area 11 is formed.
The method fully removes S impurities and inclusions in the nickel-based superalloy by electron beam refining of the superalloy, and enhances the evaporation removal of S impurity elements by utilizing the characteristics of high vacuum degree and high temperature of beam spot areas in electron beam refining; the problem of corrosion of refractory materials of the crucible in the traditional processes such as vacuum induction melting and the like is solved by utilizing the characteristic of no pollution of the water-cooled copper crucible in the refining process; by utilizing the revolutionary technology of electron beam induced solidification, the floating and aggregation of the inclusions in the smelting process are promoted according to the density difference of the inclusions and the melt and the Marangoni effect, the problem that the migration and removal mechanism of desulfurization products and inclusions containing S is single after desulfurization is solved, and the content of the S impurities in the high-temperature alloy is comprehensively reduced by combining the characteristics. The content of S impurities in the FGH4096 high-temperature alloy cast ingot prepared by the method is less than 5ppm, which is lower than that of the high-temperature alloy prepared by the traditional process, and a new method is provided for the high-purity production of the high-temperature alloy.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (6)

1. A method for promoting electron beam refining nickel-based superalloy desulfurization by adding a desulfurizing agent is characterized in that a desulfurizing agent desulfurization method is combined with an electron beam refining technology, an electron beam is used for slowly descending a beam to perform induced enrichment on impurities, trace Ca element is added before the electron beam is used for refining the nickel-based superalloy as the desulfurizing agent, the deep removal of S impurities in the process of refining the nickel-based superalloy by the electron beam is promoted, and the problem of ultrapure purification of a nickel-based superalloy base metal is solved; the inclusion containing S and the desulfurization product are induced and removed by utilizing an electron beam induced solidification technology, and the floating and aggregation of the inclusion in the smelting process are promoted according to the density difference between the inclusion and the melt and the Marangoni effect, so that the content of S impurities is further reduced;
the method comprises the following steps:
s1, pretreatment of the high-temperature alloy raw material:
s11, the raw material is FGH4096 master alloy prepared by vacuum induction melting;
s12, cutting the raw material into blocks with the length of 50mm, the width of 20mm and the height of 20mm on an online cutting lathe so as to be placed in a water-cooled copper crucible;
s13, grinding the surface of the cut raw material by using a grinder, and removing oxide skin and oil contamination impurities on the surface to ensure that the surface of the raw material is bright and clean;
s14, placing the polished raw materials in an ultrasonic cleaning machine, and respectively carrying out ultrasonic cleaning on the raw materials by using deionized water and alcohol for three times;
s15, after ultrasonic cleaning, putting the cleaned raw material into a beaker of a drying oven to prevent dust and other impurities from adhering, drying for 10min at the temperature of 80 ℃ until electron beams are refined for use;
s2, refining and purifying the high-temperature alloy by using an electron beam:
s21, cleaning the water-cooled copper crucible, the electron beam melting furnace body and the furnace wall;
s22, placing a calcium metal desulfurizer at the bottom of the water-cooled copper crucible, placing the pretreated raw material on the upper part of the calcium metal desulfurizer, and closing a furnace door after the preparation is determined and the furnace body is cleaned for refining;
s23, carrying out vacuum pre-pumping on the melting chamber and the electron gun chamber of the electron beam melting furnace to reach the target vacuum degree; preheating the electron gun after the target vacuum degree is reached;
s24, after preheating is finished, smelting the raw materials by an electron beam annular scanning path;
s25, observing whether the alloy is molten or not, and after the raw materials and the elemental calcium are completely molten and mixed in the water-cooled copper crucible, refining the raw materials for 20min to enable the elemental calcium in the high-temperature alloy melt to fully react with sulfur impurities;
s26, after the refining process is finished, controlling electron beam refining parameters to enable inclusions in the alloy to migrate to the edge of the upper surface of the ingot;
s27, turning off the high voltage of the electron gun, increasing the beam current to 60mA, and turning off the power supply of the electron gun after the high voltage value is reduced to 0kV, so that the cast ingot is fully solidified in the water-cooled copper crucible and cooled for 2 hours;
s28, taking out the electron beam refined FGH4096 alloy cast ingot after the furnace body and the cast ingot are cooled, and cutting off the impurity-enriched part of the final solidification region on the surface of the cast ingot to obtain the high-purity FGH4096 high-temperature alloy cast ingot.
2. The method for promoting the desulfurization of the electron beam refined nickel-based superalloy by adding the desulfurizing agent according to claim 1, wherein the step S21 comprises the following steps:
firstly, grinding and polishing the water-cooled copper crucible by using No. 1000 abrasive paper, then wiping the water-cooled copper crucible by using cotton cloth stained with alcohol, and drying the alcohol by using a blower after ensuring that the water-cooled copper crucible is clean and pollution-free, so as to ensure that the crucible is kept dry;
800# abrasive paper and a brush are used for cleaning pollutants on the furnace body and the furnace wall of the electron beam smelting furnace, the carbon felt covers the position which is easy to splash around the crucible, and the damage of alloy molten drop splashing to equipment in the electron beam refining process is prevented.
3. The method for promoting desulfurization of electron beam refined nickel-base superalloy according to claim 1, wherein the amount of calcium metal desulfurization agent in step S22 is 0.15 wt.%.
4. The method for promoting the desulfurization of the electron beam refined nickel-based superalloy by adding the desulfurizing agent according to claim 1, wherein the step S23 comprises the following steps:
connecting cooling water, air compressor, and power supply of electron beam refining equipment, determining that water-cooling devices of electron beam melting furnace have no water leakage, vacuumizing the melting chamber and electron gun chamber of electron beam melting furnace to target vacuum state, wherein the vacuum degree of electron gun chamber is required to be less than 5 × 10-3Pa, the vacuum degree of the smelting chamber is required to be less than 5 multiplied by 10-2Pa；
After the smelting chamber and the electron gun chamber reach the target vacuum degree, starting the electron gun, slowly adjusting the beam current to 120mA, and preheating for 12 minutes.
5. The method for promoting the desulfurization of the electron beam refined nickel-based superalloy by adding the desulfurizing agent according to claim 1, wherein the step S24 comprises the following steps:
and (3) immediately adjusting the beam current of the electron gun to 0 after preheating is finished, starting high voltage, slowly increasing the beam current of the electron gun to 450mA after the high voltage reaches 30kV and is stabilized for 1min, adjusting the radius of a beam spot to 20mm, keeping the parameters of the electron gun unchanged, and smelting the FGH4096 master alloy in an annular scanning path.
6. The method for promoting the desulfurization of the electron beam refined nickel-based superalloy by adding the desulfurizing agent according to claim 1, wherein the step S25 comprises the following steps:
observing whether the alloy is molten or not from an observation window, after the FGH4096 alloy and the metal calcium simple substance in the water-cooled copper crucible are completely molten and mixed, slowly reducing the beam current to 350mA at the speed of 30mA/min, continuously maintaining the parameters, and refining the FGH4096 mother alloy for 20min by using an electron beam annular scanning path, so that the metal calcium element in the high-temperature alloy melt and sulfur impurities fully react to generate a desulfurization product mixed with calcium sulfide, the desulfurization product is promoted to float up to the surface of the melt under the action of buoyancy and the Marangoni effect, the desulfurization product below the melt liquid level is dissolved under the local overheating condition of the melt, the desulfurization product above the melt liquid level is decomposed under the action of electron beam bombardment, and meanwhile, the volatile sulfur impurities are fully removed in the vacuum degassing reaction.
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