Low-segregation nickel-based high-temperature alloy and preparation method thereof and segregation defect control method

Abstract

The present invention belongs to the field of high-temperature alloy manufacturing, and specifically discloses a low-segregation nickel-based high-temperature alloy and a preparation method thereof, as well as a segregation defect control method. The segregation defect control method comprises: determining the melting rate of the nickel-based high-temperature alloy in the steady-state smelting stage of vacuum consumable smelting based on the content of segregation-prone elements in the nickel-based high-temperature alloy; determining the filling ratio used in the vacuum consumable smelting of the nickel-based high-temperature alloy based on the determined melting rate in the steady-state smelting stage; and vacuum consumable smelting the nickel-based high-temperature alloy according to the determined filling ratio and the determined melting rate in the steady-state smelting stage. The segregation defect control method provided by the present invention can achieve effective control of black spots, white spots and surface quality of ingots during the vacuum consumable smelting process of nickel-based high-temperature alloys.

Description

Technical Field

[0001] The present invention belongs to the field of high-temperature alloy manufacturing, and specifically relates to a method for controlling segregation defects in vacuum consumable smelting of a nickel-based high-temperature alloy, a method for preparing a low-segregation nickel-based high-temperature alloy, and a low-segregation nickel-based high-temperature alloy prepared thereby. Background Art

[0002] High-temperature alloy refers to an alloy with iron, nickel and cobalt as the matrix that can be used under complex working stresses and long-term service at temperatures above 600°C. This alloy has good comprehensive mechanical properties under high temperature conditions and is widely used in aerospace, petroleum, chemical and other fields.

[0003] At present, some high-quality high-temperature alloys use vacuum consumable smelting as a secondary smelting process. A large number of studies have shown that vacuum consumable smelting has an important impact on the quality of high-temperature alloy products. At present, white spots and black spots in consumable ingots are the main problems in vacuum consumable smelting of high-temperature alloys. Studies have shown that black spots are a channel-type macro-segregation defect, which significantly reduces the toughness, yield strength and durability of the material, resulting in material waste, and severely restricting the development of high-temperature alloy varieties and properties. In addition, the generation of white spots will lead to differences in strengthening elements and precipitation phases between white spots and the matrix. Compared with the matrix, the strengthening elements and grain boundary precipitation phases in the white spot area are less. Generally, the generation of white spots will seriously affect the long-term creep and other properties of high-temperature alloy products. At the production site, once white spots are found in high-temperature alloy products, the products will be scrapped in serious cases. It can be seen that reducing or eliminating the generation of black spots and white spots in the vacuum consumable smelting process plays an important role in the manufacture and development of high-temperature alloys.

[0004] Existing studies have found that in the process of vacuum consumable smelting, black spots mainly depend on alloy composition, smelting parameters, etc. For alloys with high content of segregation elements such as W, Mo, Al, and Ti, it is necessary to control the smelting parameters to obtain a shallow and flat molten pool to avoid the formation of black spots. For white spots, studies have found that typical white spot defects are caused by the falling of the ingot crown without melting. Among them, the ingot crown refers to a layer of metal with a high inclusion content higher than the ingot body formed at the top of the high-temperature alloy vacuum arc remelting ingot, near the inner wall of the crystallizer around the annular periphery. This type of white spot is mainly affected by factors such as filling ratio and melting rate. Under a certain ingot shape, generally with the increase of the filling ratio, the electromagnetic force directed to the inside of the molten pool on the ingot crown increases significantly, increasing the ingot crown's lodging and breaking and falling into the molten pool, which will increase the formation of white spots. However, under a certain ingot shape, with the increase of the melting rate, the ingot crown drop is more likely to be melted in a deeper molten pool, which can reduce the formation of white spots. In addition, the filling ratio also affects the molten pool to the edge. Generally, increasing the filling ratio is conducive to the heat transfer from the molten pool to the side crystallizer, and the molten pool to the edge is better, resulting in good surface quality of the ingot, less peeling, and high yield rate. At present, relevant technologies and inventions have carried out some research work on improving the segregation of black spots and white spots in vacuum consumable ingots, but the research work and the results achieved are still somewhat insufficient. For example, the inherent optimization relationship between key parameters such as high-temperature alloy composition, melting rate, and filling ratio has not been clarified, which leads to the inability to effectively solve the problems of black spots, white spots, and poor surface quality in vacuum consumable smelting of high-temperature alloys.

[0005] In view of this, the existing high-temperature alloy preparation method needs to be improved. Summary of the invention

[0006] The main purpose of the present invention is to address the deficiencies in the above-mentioned prior art and to provide a method for controlling segregation defects in vacuum consumable smelting of nickel-based high-temperature alloys and a method for preparing low-segregation nickel-based high-temperature alloys, aiming to avoid black spots while reducing white spot segregation defects during vacuum consumable smelting to prepare low-segregation nickel-based high-temperature alloy ingots.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] According to a first aspect of the present invention, a method for controlling segregation defects in vacuum consumable smelting of a nickel-based high-temperature alloy is provided, which comprises the following steps:

[0009] Determining the melting rate of the nickel-based high-temperature alloy in a steady-state melting stage of vacuum consumable smelting based on the content of segregation-prone elements in the nickel-based high-temperature alloy;

[0010] Determining a filling ratio used in vacuum consumable smelting of the nickel-based high-temperature alloy based on the determined melting rate in the steady-state melting stage;

[0011] According to the determined filling ratio and the determined melting rate in the steady-state melting stage, the nickel-based high-temperature alloy is subjected to vacuum consumable smelting.

[0012] According to some embodiments of the present invention, the easily segregated element includes at least one of W, Mo, Al, and Ti.

[0013] According to some embodiments of the present invention, based on the content of segregation-prone elements in the nickel-based high-temperature alloy, determining the melting rate of the nickel-based high-temperature alloy in the steady-state melting stage of vacuum consumable smelting includes:

[0014] When the content of the segregation-prone element is within the specified range, the melting rate in the steady-state melting stage is set to 3.0-3.4 kg / min;

[0015] When the content of the segregation-prone element is lower than the specified range, the melting rate in the steady-state melting stage is set to 3.5-4.2 kg / min.

[0016] Wherein, the specified range is: W: 1.5~4.5%, Mo: 3.5~4.5%, Al: 1.0~2.5%, Ti: 2.0~3.0%.

[0017] According to some embodiments of the present invention, based on the determined melting rate in the steady-state melting stage, determining the filling ratio used in the vacuum consumable smelting of the nickel-based high-temperature alloy includes:

[0018] When the melting rate in the steady-state melting stage is 3.0-3.4 kg / min, the filling ratio is set to 0.65-0.72;

[0019] When the melting rate in the steady-state melting stage is 3.5-4.2 kg / min, the filling ratio is set to 0.73-0.80.

[0020] According to some embodiments of the present invention, based on the determined melting rate in the steady-state melting stage, determining the filling ratio used in the vacuum consumable smelting of the nickel-based high-temperature alloy includes:

[0021] When the melting rate in the steady-state melting stage is 3.0-3.4 kg / min, the filling ratio is determined based on the melting rate according to the following formula: y=0.175x+0.13, wherein y is the filling ratio and x is the melting rate;

[0022] When the melting rate in the steady-state melting stage is 3.5-4.2 kg / min, the filling ratio is determined based on the melting rate according to the following formula: y=0.1x+0.38, wherein y is the filling ratio and x is the melting rate.

[0023] According to some embodiments of the present invention, vacuum consumable smelting is performed on the nickel-based high-temperature alloy according to the determined filling ratio and the determined melting rate in the steady-state smelting stage, including:

[0024] determining a diameter of a nickel-based high-temperature alloy consumable electrode based on the determined filling ratio;

[0025] A consumable electrode of a required diameter is prepared and vacuum consumable smelting is performed using the consumable electrode to obtain a nickel-based high-temperature alloy consumable ingot.

[0026] According to some embodiments of the present invention, a consumable electrode of a desired diameter is prepared by controlling the size of the vacuum induction ingot and the amount of ingot stripping.

[0027] According to a second aspect of the present invention, there is provided a method for preparing a low-segregation nickel-based high-temperature alloy, comprising the following steps:

[0028] Preparation of nickel-based high-temperature alloy consumable electrodes;

[0029] The nickel-based high-temperature alloy consumable electrode is used to perform vacuum consumable smelting to obtain a nickel-based high-temperature alloy consumable ingot.

[0030] The melting rate in the steady-state melting stage of the vacuum consumable smelting is determined based on the content of the easily segregated elements in the nickel-based high-temperature alloy, and the filling ratio used in the vacuum consumable smelting is determined based on the melting rate in the steady-state melting stage.

[0031] According to some embodiments of the present invention, in the arc starting stage of the vacuum consumable smelting, the current is controlled to be 4.0~8.0kA, the voltage is controlled to be 22.0~24.0V, and the inert gas pressure is controlled to be 0Pa; in the steady-state smelting stage of the vacuum consumable smelting, the melting rate is controlled to be 3.0~4.2kg / min, the droplet is controlled to be 3~10 1 / s, and the inert gas pressure gradually increases from 0Pa to 400~800Pa; in the hot capping stage of the vacuum consumable smelting, the melting rate is controlled to be 1.5~4.0kg / min, and the droplet is controlled to be 10~18 1 / s.

[0032] According to a third aspect of the present invention, there is provided a low-segregation nickel-based high-temperature alloy, which is prepared by the method described in the second aspect of the present invention.

[0033] By adopting the above technical solution, the present invention has the following beneficial effects:

[0034] The method for controlling segregation defects in vacuum consumable smelting of nickel-based high-temperature alloys provided by the present invention first determines the smelting melting rate according to the alloy composition and segregation characteristics to avoid the formation of black spot defects by segregated elements during the smelting process; on this basis, the filling ratio is determined according to the melting rate to reduce the generation of white spots during the smelting process, while improving the surface quality of the ingot, reducing the amount of ingot surface peeling, and improving the yield rate. The method for controlling segregation defects provided by the present invention can achieve effective control of black spots, white spots, and surface quality of ingots during the vacuum consumable smelting process of nickel-based high-temperature alloys by optimizing the intrinsic relationship between key parameters such as nickel-based high-temperature alloy composition, melting rate, and filling ratio.

[0035] The preparation method of the low-segregation nickel-based high-temperature alloy provided by the present invention can avoid the formation of black spot defects by the easily segregated elements during the smelting process by determining the melting rate in the steady-state smelting stage of vacuum consumable smelting based on the content of the easily segregated elements in the nickel-based high-temperature alloy; and can reduce the generation of white spots during the smelting process by determining the filling ratio adopted by vacuum consumable smelting based on the melting rate in the steady-state smelting stage. The preparation method of the present invention can improve the surface quality of the ingot while effectively solving the white spots and black spots, reduce the amount of ingot peeling, and prepare high-quality and high-yield ingots. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The present invention provides a flow chart of the method for controlling segregation defects in vacuum consumable smelting of nickel-based high-temperature alloys.

[0037] Figure 2 The present invention provides a flow chart of a method for preparing a low-segregation nickel-based high-temperature alloy.

[0038] Figure 3 Figure 2 is the molten pool depth diagram at different melting rates.

[0039] Figure 4 These are low-magnification scanning electron microscope photos of nickel-based high-temperature alloy consumable ingots prepared in some embodiments and comparative examples.

[0040] Figure 5 The following are photos of consumable ingots of nickel-based high-temperature alloys prepared in some embodiments and comparative examples. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0042] As required, specific embodiments of the present invention are disclosed in the present specification; however, it should be understood that the embodiments disclosed herein are merely examples of the present invention that can be implemented in multiple, alternative forms. In the following description, multiple operating parameters and components are described in multiple embodiments contemplated. These specific parameters and components are only used as examples in this specification and are not meant to be limiting.

[0043] As mentioned in the background technology section, existing studies have found that in the vacuum consumable smelting process, black spots mainly depend on alloy composition, smelting parameters, etc. For alloys with high content of easily segregated elements such as W, Mo, Al, and Ti, it is necessary to control the smelting parameters to obtain a shallow molten pool to avoid the formation of black spots. The study also found that typical white spot defects will be produced by the unmelted ingot crown falling off, and this type of white spot defect is mainly affected by factors such as filling ratio and melting rate. Under a certain ingot shape, generally with the increase of the filling ratio, the electromagnetic force directed to the inside of the molten pool on the ingot crown is significantly increased, which increases the situation of the ingot crown falling and breaking and falling into the molten pool, which will increase the formation of white spots. However, under a certain ingot shape, with the increase of the melting rate, the ingot crown drops are more likely to melt in a deeper molten pool, which can reduce the formation of white spots. Not only that, the filling ratio also affects the molten pool to the edge. Generally, increasing the filling ratio is conducive to the heat transfer of the molten pool to the side crystallizer, and the molten pool to the edge is better, resulting in good surface quality of the ingot, less peeling, and high yield. In view of this, the present invention formulates different melting rate ranges according to the nickel-based alloy composition and segregation tendency, determines the smelting process of different alloy composition-melting rate-filling ratio according to the influence of melting rate and filling ratio on the white spots and surface quality of the ingot, and realizes the effective control of the black spots, white spots and surface quality of the ingot in the consumable smelting process. In the actual production site, under the condition of a certain ingot shape, different grades of high-temperature alloy components have different segregation tendencies and different smelting melting rate ranges. It is necessary to formulate a suitable filling ratio range to reduce the generation of white spots and black spots defects and obtain high-temperature alloy ingots with high surface quality.

[0044] According to a first aspect of the present invention, a method for controlling segregation defects in vacuum consumable smelting of nickel-based high-temperature alloy is provided. Figure 1As shown, the segregation defect control method includes the following steps: S1: based on the content of segregation-prone elements in the nickel-based high-temperature alloy, determine the melting rate of the nickel-based high-temperature alloy in the steady-state smelting stage of vacuum consumable smelting; S2: based on the determined melting rate in the steady-state smelting stage, determine the filling ratio used in the vacuum consumable smelting of the nickel-based high-temperature alloy; S3: vacuum consumable smelting the nickel-based high-temperature alloy according to the determined filling ratio and the determined melting rate in the steady-state smelting stage. The segregation defect control method provided by the present invention first determines the smelting melting rate according to the alloy composition and segregation characteristics to avoid the formation of black spot defects by segregation-prone elements during the smelting process; on this basis, the filling ratio is determined according to the melting rate to reduce the generation of white spots during the smelting process, while improving the surface quality of the ingot, reducing the amount of ingot surface peeling, and improving the yield rate. The segregation defect control method provided by the present invention can achieve effective control of black spots, white spots, and surface quality of the ingot during the vacuum consumable smelting process of the nickel-based high-temperature alloy by optimizing the intrinsic relationship between key parameters such as the composition, melting rate, and filling ratio of the nickel-based high-temperature alloy.

[0045] The "filling ratio used in vacuum consumable smelting" mentioned in this article refers to the ratio of the consumable electrode area to the crystallizer area used in the vacuum consumable smelting stage. The filling ratio has an important influence on the solidification quality of the smelting ingot.

[0046] In some embodiments, the easily segregated element in the nickel-based high-temperature alloy includes at least one of W, Mo, Al, and Ti. Specifically, the nickel-based high-temperature alloy may contain only one of W, Mo, Al, and Ti, or only two or three of them, or all of them.

[0047] In some embodiments, in step S1, based on the content of easily segregated elements in the nickel-based high-temperature alloy, the melting rate of the nickel-based high-temperature alloy in the steady-state melting stage of vacuum consumable smelting is determined, including: when the content of easily segregated elements is in a specified range, the melting rate in the steady-state melting stage is set to 3.0~3.4kg / min; when the content of easily segregated elements is lower than the specified range, the melting rate in the steady-state melting stage is set to 3.5~4.2kg / min, wherein the specified range is: W: 1.5~4.5%, Mo: 3.5~4.5%, Al: 1.0~2.5%, Ti: 2.0~3.0%. In the present invention, according to the segregation characteristics of nickel-based high-temperature alloy components, for alloys with high content of elements prone to segregation, in order to effectively avoid the typical defects of black spots during the smelting process, a low melting rate use range (3.0~3.4kg / min) is formulated; for alloys with low content of elements prone to segregation, in order to improve production efficiency, a high melting rate use range (3.5~4.2kg / min) is formulated to shorten the smelting cycle and reduce production costs.

[0048] In some embodiments, in step S2, based on the determined melting rate in the steady-state melting stage, the filling ratio used in the vacuum consumable smelting of the nickel-based high-temperature alloy is determined, including: when the melting rate in the steady-state melting stage is 3.0~3.4kg / min, the filling ratio is set to 0.65~0.72; when the melting rate in the steady-state melting stage is 3.5~4.2kg / min, the filling ratio is set to 0.73~0.80. In the present invention, for the low melting rate use range (3.0~3.4kg / min), a small filling ratio range (0.65~0.72) is adopted to avoid the ingot crown being subjected to a large electromagnetic force directed to the inside of the molten pool during the smelting process, causing the ingot crown to fall over and break, and fall into a shallow molten pool (low melting rate, shallow and flat molten pool) where it is difficult to completely ablate, resulting in white spot defects. In the case of exceeding the above filling ratio range, if the filling ratio is large, the ingot will be subjected to a large inward electromagnetic force, which will easily cause it to fall over and break, and increase the probability of white spots. If the filling ratio is small, the molten pool to the edge and the surface quality of the ingot are poor, the amount of peeling is large, and the yield rate is low. For the high melting rate range (3.5~4.2kg / min), a large filling ratio range (0.73~0.80) is adopted. On the one hand, with a large filling ratio, although the ingot crown is subjected to a large electromagnetic force directed to the inside of the molten pool, the ingot crown may fall over and break, but it can be completely melted when it falls into the deep molten pool (high melting rate, deep V-shaped molten pool), which can avoid the formation of white spots; on the other hand, a large filling ratio is conducive to the heat transfer of the molten pool to the side crystallizer and helium, the molten pool is good to the edge, the surface quality of the ingot is good, which is conducive to reducing the amount of ingot peeling and improving the yield rate. If the filling ratio is beyond the above range, the arc safety will be affected if the filling ratio is too large; if the filling ratio is too small, the molten pool will transfer less heat to the side mold and helium, and the molten pool will be poor to the edge, making it difficult to improve the surface quality of the ingot and reduce the amount of peeling on the ingot surface. At the same time, the molten pool formed when the filling ratio is small is deeper, which is easy to form black spot defects.

[0049] In some embodiments, in step S3, based on the determined melting rate in the steady-state melting stage, the filling ratio used in the vacuum consumable smelting of the nickel-based high-temperature alloy is determined, including: when the melting rate in the steady-state melting stage is 3.0~3.4kg / min, the filling ratio is determined based on the melting rate according to the following formula: y=0.175x+0.13, wherein y is the filling ratio and x is the melting rate; when the melting rate in the steady-state melting stage is 3.5~4.2kg / min, the filling ratio is determined based on the melting rate according to the following formula: y=0.1x+0.38, wherein y is the filling ratio and x is the melting rate.

[0050] In some embodiments, in step S3, vacuum consumable smelting is performed on the nickel-based high-temperature alloy according to the determined filling ratio and the determined melting rate in the steady-state smelting stage, including: determining the diameter of the nickel-based high-temperature alloy consumable electrode based on the determined filling ratio; preparing a consumable electrode of a required diameter and using the consumable electrode to perform vacuum consumable smelting to obtain a nickel-based high-temperature alloy consumable ingot.

[0051] In some embodiments, a consumable electrode of a desired diameter is prepared by controlling the size of the vacuum induction ingot and the amount of ingot stripping.

[0052] According to a second aspect of the present invention, a method for preparing a low-segregation nickel-based high-temperature alloy is provided, such as Figure 2 As shown, the preparation method includes the following steps: S10: preparing a nickel-based high-temperature alloy consumable electrode; S20: using the nickel-based high-temperature alloy consumable electrode to perform vacuum consumable smelting to obtain a nickel-based high-temperature alloy consumable ingot. Among them, the melting rate in the steady-state smelting stage of the vacuum consumable smelting is determined based on the content of the easily segregated elements in the nickel-based high-temperature alloy, and the filling ratio used in the vacuum consumable smelting is determined based on the melting rate in the steady-state smelting stage. The preparation method of the low-segregation nickel-based high-temperature alloy provided by the present invention can avoid the formation of black spot defects by the easily segregated elements during the smelting process by determining the melting rate in the steady-state smelting stage of the vacuum consumable smelting based on the content of the easily segregated elements in the nickel-based high-temperature alloy; by determining the filling ratio used in the vacuum consumable smelting based on the melting rate in the steady-state smelting stage, the generation of white spots during the smelting process can be reduced. The preparation method of the present invention can improve the surface quality of the ingot while effectively solving the white spots and black spots, reduce the amount of ingot peeling, and prepare an ingot with high quality and high yield.

[0053] The preparation of consumable electrodes mainly includes several processes such as vacuum induction ingot preparation-annealing-sawing-skinning-baking-welding, etc. Among these processes, the most important is to control the diameter, that is, the area, of the consumable electrode by controlling the size of the vacuum induction ingot and the amount of ingot skinning, and then control the smelting filling ratio.

[0054] Vacuum consumable smelting includes arc starting stage, steady-state melting stage and hot capping stage, among which the arc starting stage and hot capping stage are unstable smelting stages, and the corresponding bottom and head of the ingot must be cut off, while the steady-state melting stage plays an important role in the quality of the ingot. Therefore, the smelting melting rate concerned in this technology is the melting rate in the steady-state melting stage.

[0055] In some embodiments, in the arc starting stage of vacuum consumable smelting, the current is controlled to be 4.0~8.0kA, the voltage is controlled to be 22.0~24.0V, and the inert gas pressure is controlled to be 0Pa; in the steady-state smelting stage of vacuum consumable smelting, the melting rate is controlled to be 3.0~4.2kg / min, the droplet is controlled to be 3~10 1 / s, and the inert gas pressure gradually increases from 0Pa to 400~800Pa; in the hot capping stage of vacuum consumable smelting, the melting rate is controlled to be 1.5~4.0kg / min, and the droplet is controlled to be 10~18 1 / s.

[0056] In some embodiments, in step S20, using a nickel-based high-temperature alloy consumable electrode for vacuum consumable smelting to obtain a nickel-based high-temperature alloy consumable ingot includes: placing the consumable electrode in a consumable furnace, closing the furnace door, and starting to evacuate. When the vacuum degree and the leakage rate meet the requirements, that is, the vacuum degree is <0.10Pa and the leakage rate is <0.10Pa / min, power can be supplied to start smelting and enter the arc starting stage; the arc starting stage adopts current + voltage control, the current is 4.0~8.0kA, the voltage is 22.0~24.0V, and the inert gas pressure during the arc starting period is 0Pa; the steady-state smelting stage adopts droplet + melting rate control, the melting rate is 3.0~4.2kg / min, and the droplet is 3~10 1 / s, the inert gas pressure in the steady-state smelting stage gradually increases from 0Pa to the inert gas pressure used in the steady-state stage, and its pressure range is 400Pa~800Pa; the hot capping stage adopts the molten droplet + melting speed control, the melting speed is 1.5~4.0kg / min, the molten droplet is 10~18 1 / s, and the melting speed and inert gas pressure in the hot capping stage gradually decrease from the steady-state stage value and remain stable. The inert gas mentioned in the present invention can be helium.

[0057] According to the influence of the key parameters of alloy composition, melting rate and filling ratio on the white spots, black spots and surface quality of consumable ingots, the present invention formulates the control order of black spots, white spots and surface quality of ingots. First, according to the alloy composition and segregation characteristics, a smelting melting rate range is formulated to avoid the formation of black spot defects in the alloy that is easy to segregate during the smelting process. On this basis, according to the influence of the molten pool depth and filling ratio under different smelting melting rate ranges on the white spots and surface quality of the ingots, different filling ratio ranges are formulated to reduce the generation of white spots in the smelting process, while improving the surface quality of the ingots, reducing the amount of ingot surface peeling, and improving the yield rate. By optimizing the intrinsic relationship between the key parameters such as nickel-based high-temperature alloy composition, melting rate, filling ratio, etc., the black spots, white spots and surface quality problems of nickel-based high-temperature alloy vacuum consumable ingots can be effectively controlled, and high-quality high-temperature alloy products can be prepared.

[0058] According to a third aspect of the present invention, there is provided a low-segregation nickel-based high-temperature alloy, which is prepared by the method described in the second aspect of the present invention.

[0059] The present invention is further described below in conjunction with specific examples, but the present invention is not limited in any way. To avoid redundant description, the methods used are all conventional methods unless otherwise specified.

[0060] Embodiment 1:

[0061] 1) The chemical composition of the nickel-based high-temperature alloy used is: C≦0.08, Cr: 17~20%, W: 4~5%, Mo: 4~5%, Al: 1~1.5%, Ti: 2.2~2.8%, and the balance is Ni and some inevitable impurity elements. The consumable smelting electrode rod is prepared through vacuum induction smelting and pouring-annealing-sawing-skinning-baking-welding and other processes. Among them, the induction ingot diameter obtained in the induction ingot pouring process is 440mm, and the electrode rod with a diameter of 424mm is obtained after skinning, and the smelting filling ratio used is 0.7.

[0062] 2) The electrode rod in step 1) is placed in a Φ508mm ingot-shaped consumable furnace as a consumable electrode, the furnace door is closed, and vacuuming is started. When the vacuum degree and leakage rate meet the requirements, that is, the vacuum degree is <0.1Pa and the leakage rate is <0.1Pa / min, power can be supplied to start smelting. The arc starting stage of consumable smelting is from 0 to 20 minutes. The arc starting stage adopts current + voltage control. The current gradually increases from 4.5kA to 7.5kA and then stabilizes. The voltage gradually increases from 22V to 24V and then stabilizes. The helium pressure in the arc starting stage is 0Pa.

[0063] 3) The time from 21 to 720 minutes is the steady-state smelting stage of consumable smelting. The steady-state smelting stage adopts molten droplet + melting rate control, the number of molten droplets is 7.0 1 / s, the melting rate is 3.4 kg / min, and helium is filled when the smelting time reaches 100 minutes. When the smelting time reaches 150 minutes, the helium pressure increases to 500 Pa and then tends to be stable.

[0064] 4) The period from 721 to 800 minutes is the hot capping stage of consumable smelting. The hot capping stage adopts molten droplet + melting rate control, the number of molten droplets is 11~16 1 / s, and the melting rate is 1.5~3.4kg / min. The period from 721 to 750 minutes is the early stage of hot capping smelting. During this period, the melting rate gradually decreases from 3.4kg / min to 1.8 kg / min, and the helium pressure used is reduced from 500Pa to 350Pa. The period from 751 to 800 minutes is the late stage of hot capping smelting, that is, the low melting rate insulation smelting stage (smelting time is 50 minutes). During this period, the melting rate gradually decreases from 1.8kg / min to 1.5 kg / min, and the helium pressure used is maintained at 350Pa.

[0065] 5) After the hot capping is completed, the ingot is cooled in the crystallizer for 120 minutes and then removed from the mold, and a consumable ingot is obtained after air cooling.

[0066] Embodiment 2:

[0067] The only difference from Example 1 is that by controlling the size of the vacuum induction ingot and the amount of ingot peeling, an electrode rod with a diameter of Φ410 mm is prepared, and the filling ratio used is 0.65. In this case, the depth of the metal molten pool is small, the inward electromagnetic force on the ingot crown is small, and no black spots or white spots appear.

[0068] Embodiment 3:

[0069] The only difference from Example 1 is that by controlling the size of the vacuum induction ingot and the amount of ingot peeling, an electrode rod with a diameter of Φ430 mm is prepared, and the filling ratio used is 0.72. In this case, no white spots or black spots appear in the molten pool, and the surface quality of the ingot is good.

[0070] Embodiment 4:

[0071] The only difference from Example 1 is that the melting rate in the steady-state melting stage of the consumable smelting is 3.0 kg / min. In this case, no white spots or black spots appear in the molten pool.

[0072] Embodiment 5:

[0073] The only difference from Example 1 is that: (1) the chemical composition of the nickel-based high-temperature alloy used is: C≦0.08, Cr: 17~21%, Ni: 50~55%, Co≦1%, Mo: 2.8~3.3%, Al: 0.2~0.8%, Ti: 0.65~1.15%, Nb: 4.75~5.5%, and the balance is Fe and unavoidable impurity elements. (2) The melting rate in the steady-state melting stage of consumable smelting is 3.9kg / min; (3) The diameter of the electrode rod used is 440mm, and the filling ratio is 0.75. In this case, no black spots or white spots appear on the ingot, and the surface quality is good.

[0074] Embodiment 6:

[0075] The only difference from Example 5 is that by controlling the size of the vacuum induction ingot and the amount of ingot peeling, an electrode rod with a diameter of Φ433 mm is prepared, and the filling ratio used is 0.73. In this case, the ingot has no white spots or black spots, and the surface quality is good.

[0076] Embodiment 7:

[0077] The only difference from Example 5 is that by controlling the size of the vacuum induction ingot and the amount of ingot peeling, an electrode rod with a diameter of Φ454 mm is prepared, and the filling ratio used is 0.8. In this case, the ingot has no white spots or black spots, and the surface quality is good.

[0078] Embodiment 8:

[0079] The only difference from Example 5 is that the melting rate in the steady-state melting stage of the consumable smelting is 3.5 kg / min. In this case, no white spots or black spots appear in the molten pool.

[0080] Embodiment 9:

[0081] The only difference from Example 5 is that the melting rate in the steady-state melting stage of the consumable smelting is 4.2 kg / min. In this case, no white spots or black spots appear in the molten pool, and the surface quality of the ingot is good.

[0082] Comparative Example 1:

[0083] The only difference from Example 1 is that by controlling the size of the vacuum induction ingot and the amount of ingot peeling, an electrode rod with a diameter of Φ406 mm is prepared, and the filling ratio used is 0.64. In this case, the surface quality of the ingot is poor.

[0084] Comparative Example 2:

[0085] The only difference from Example 1 is that by controlling the size of the vacuum induction ingot and the amount of ingot peeling, an electrode rod with a diameter of Φ433 mm is prepared, and the filling ratio used is 0.73. In this case, the ingot crown is subjected to a large inward electromagnetic force, resulting in lodging and breaking, and the broken ingot crown falls into the shallow metal molten pool, which is difficult to completely melt, forming white spots.

[0086] Comparative Example 3:

[0087] The only difference from Example 1 is that the melting rate in the steady-state melting stage is 2.9 kg / min, that is, a relatively small melting rate is used for smelting. In this case, the molten pool does not reach the edge during the smelting process, the surface quality of the ingot is poor, and the amount of ingot peeling is large.

[0088] Comparative Example 4:

[0089] The only difference from Example 1 is that the melting rate in the steady-state melting stage is 3.5 kg / min, that is, a larger melting rate is used for smelting. In this case, the smelting pool depth and the mushy zone are large, the local solidification time of the alloy is long, and black spot defects appear in the ingot.

[0090] Comparative Example 5:

[0091] The only difference from Example 5 is that by controlling the size of the vacuum induction ingot and the amount of ingot peeling, an electrode rod with a diameter of Φ400 mm was prepared, and the filling ratio used was 0.72. In this case, the surface quality of the ingot was poor.

[0092] Comparative Example 6:

[0093] The only difference from Example 5 is that by controlling the size of the vacuum induction ingot and the amount of ingot peeling, an electrode rod with a diameter of Φ456 mm is prepared, and the filling ratio used is 0.81. In this case, the arc safety is poor.

[0094] Comparative Example 7:

[0095] The only difference from Example 5 is that the melting rate in the steady-state smelting stage is 3.4 kg / min, that is, a smaller melting rate is used for smelting. In this case, the molten pool during the smelting process is shallow and flat, and the ingot crown falls into the molten pool and is difficult to be completely melted, forming white spots.

[0096] The present invention firstly uses Meltflow to analyze the influence of melting rate on molten pool depth and white spot melting. Figure 3 As shown in the results, it is found that increasing the melting rate and increasing the molten pool depth are beneficial to the melting of white spots. Then, the influence of the filling ratio on the depth of the metal molten pool and the edge of the molten pool is analyzed. As shown in Table 1, with the increase of the filling ratio, the thickness of the mushy area at the edge of the molten pool gradually decreases, and the molten pool to the edge and the surface quality are better. In addition, by consulting relevant literature, the influence of the filling ratio on the electromagnetic force on the ingot crown is clarified. It is found that with the increase of the filling ratio, the electromagnetic force on the ingot crown increases, and the risk of white spots increases. According to the influence of melting rate and filling ratio on white spots and black spots, a reasonable range of alloy composition, smelting melting rate and filling ratio is formulated, which effectively reduces the black spots and white spots of the ingot and improves the surface quality of the ingot.

[0097] Table 1 Thickness of mushy zone at the edge of molten pool under different filling ratios

[0098]

[0099] At the same time, the low magnification and surface peeling conditions of some nickel-based high-temperature alloys prepared in the embodiments and comparative examples were obtained at the production site, such as Figure 4 As shown, the ingot of Example 1 has no black spots or white spots at low magnification, while the white spots appear in Comparative Example 2. Figure 5 It can be seen that the surface quality of Example 1 is good, and the amount of peeling on the surface of the ingot is 10mm, while the surface quality of the ingot of Comparative Example 1 is poor, and the amount of peeling on the surface is 15mm. The above results show that the technical solution proposed in the present invention can effectively control the white spots, black spots and surface quality of the ingot of consumable smelting, and prepare high-quality high-temperature alloy products.

[0100] Finally, it should be noted that the embodiments described above are only some embodiments of the present invention, not all embodiments. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but only represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. A method for controlling segregation defects in vacuum consumable smelting of nickel-based high-temperature alloys, characterized in that: The following steps are involved: Based on the content of segregation-prone elements in the nickel-based high-temperature alloy, the melting rate of the nickel-based high-temperature alloy in the steady-state melting stage of vacuum consumable smelting is determined, the segregation-prone elements include at least one of W, Mo, Al, and Ti, when the content of the segregation-prone elements is in a specified range, the melting rate in the steady-state melting stage is set to 3.0-3.4 kg / min, when the content of the segregation-prone elements is lower than the specified range, the melting rate in the steady-state melting stage is set to 3.5-4.2 kg / min, wherein the specified range is: W: 1.5-4.5%, Mo: 3.5-4.5%, Al: 1.0-2.5%, Ti: 2.0-3.0%; Based on the determined melting rate in the steady-state melting stage, the filling ratio used in the vacuum consumable smelting of the nickel-based high-temperature alloy is determined. When the melting rate in the steady-state melting stage is 3.0-3.4 kg / min, the filling ratio is set to 0.65-0.

72. When the melting rate in the steady-state melting stage is 3.5-4.2 kg / min, the filling ratio is set to 0.73-0.

80. According to the determined filling ratio and the determined melting rate in the steady-state melting stage, the nickel-based high-temperature alloy is subjected to vacuum consumable smelting.

2. The method for controlling segregation defects in vacuum consumable smelting of nickel-based high-temperature alloy according to claim 1, characterized in that: Based on the determined melting rate in the steady-state melting stage, the filling ratio used in the vacuum consumable smelting of the nickel-based high-temperature alloy is determined, including: When the melting rate in the steady-state melting stage is 3.0-3.4 kg / min, the filling ratio is determined based on the melting rate according to the following formula: y=0.175x+0.13, wherein y is the filling ratio and x is the melting rate; When the melting rate in the steady-state melting stage is 3.5-4.2 kg / min, the filling ratio is determined based on the melting rate according to the following formula: y=0.1x+0.38, wherein y is the filling ratio and x is the melting rate.

3. The method for controlling segregation defects in vacuum consumable smelting of nickel-based high-temperature alloy according to claim 1, characterized in that: According to the determined filling ratio and the determined melting rate in the steady-state melting stage, the nickel-based high-temperature alloy is subjected to vacuum consumable smelting, including: determining a diameter of a nickel-based high-temperature alloy consumable electrode based on the determined filling ratio; A consumable electrode of a required diameter is prepared and vacuum consumable smelting is performed using the consumable electrode to obtain a nickel-based high-temperature alloy consumable ingot.

4. The method for controlling segregation defects in vacuum consumable smelting of nickel-based high-temperature alloy according to claim 3, characterized in that: The consumable electrode with the required diameter can be prepared by controlling the size of the vacuum induction ingot and the amount of ingot peeling.

5. A method for preparing a low-segregation nickel-based high-temperature alloy, characterized in that: The following steps are involved: Preparation of nickel-based high-temperature alloy consumable electrodes; The nickel-based high-temperature alloy consumable electrode is used to perform vacuum consumable smelting to obtain a nickel-based high-temperature alloy consumable ingot. The melting rate in the steady-state melting stage of the vacuum consumable smelting is determined based on the content of the easily segregated elements in the nickel-based high-temperature alloy, and the filling ratio adopted by the vacuum consumable smelting is determined based on the melting rate in the steady-state melting stage. The easily segregated elements include at least one of W, Mo, Al, and Ti. When the content of the easily segregated elements is within a specified range, the melting rate in the steady-state melting stage is set to 3.0-3.4 kg / min. When the content of the easily segregated elements is lower than the specified range, the steady-state melting stage is set to 3.0-3.4 kg / min. The melting rate in the melting stage is set to 3.5~4.2kg / min, wherein the specified range is: W: 1.5~4.5%, Mo: 3.5~4.5%, Al: 1.0~2.5%, Ti: 2.0~3.0%, when the melting rate in the steady-state melting stage is 3.0~3.4kg / min, the filling ratio is set to 0.65~0.72, and when the melting rate in the steady-state melting stage is 3.5~4.2kg / min, the filling ratio is set to 0.73~0.

80.

6. The method for preparing a low-segregation nickel-based high-temperature alloy according to claim 5, characterized in that: In the arc starting stage of the vacuum consumable smelting, the current is controlled to be 4.0~8.0kA, the voltage is controlled to be 22.0~24.0V, and the inert gas pressure is controlled to be 0Pa; in the steady-state smelting stage of the vacuum consumable smelting, the melting rate is controlled to be 3.0~4.2kg / min, the molten droplet is controlled to be 3~101 / s, and the inert gas pressure gradually increases from 0Pa to 400~800Pa; in the hot capping stage of the vacuum consumable smelting, the melting rate is controlled to be 1.5~4.0kg / min, and the molten droplet is controlled to be 10~18 1 / s.

7. A low-segregation nickel-based high-temperature alloy, characterized in that: The method is prepared by any one of claims 5 to 6.

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