A low metallurgical defect high-temperature alloy and a preparation method thereof

Abstract

The present application relates to the technical field of high-temperature alloy, and provides a low-metallurgical defect high-temperature alloy and a preparation method thereof, the preparation method comprising the following steps: S1, preparing a high-temperature alloy consumable electrode; S2, vacuum consumable smelting the high-temperature alloy consumable electrode to obtain a low-metallurgical defect high-temperature alloy; in the process of vacuum consumable smelting, the filling ratio of the steady-state smelting stage is gradually reduced; according to the filling ratio of the steady-state smelting stage, the smelting melting speed and the smelting droplet number of the steady-state smelting stage are determined correspondingly. The preparation method of the low-metallurgical defect high-temperature alloy provided by the present application realizes the accurate control of white spots by mastering the internal relationship between the smelting filling ratio, the melting droplet number, the melting speed and the white spots; compared with the prior art, the present application does not have higher requirements for the diameter range of the electrode rod head and tail, does not increase the amount of electrode rod peeling, reduces the yield, and the operability of the method is stronger, which does not significantly affect the production cycle and cost.

Description

Technical Field

[0001] This invention relates to the field of high-temperature alloy technology, and in particular to a high-temperature alloy with low metallurgical defects and its preparation method. Background Technology

[0002] High-temperature alloys are a class of high-performance metallic materials that can operate stably for extended periods under high temperature (above 600℃), high pressure, corrosive environments, and high mechanical stress conditions. Due to their excellent properties, high-temperature alloys are widely used in aerospace, energy, chemical and other fields, becoming the cornerstone of modern industrial "high-precision" equipment.

[0003] Vacuum arc remelting (VAR) is a key metallurgical technology for preparing high-performance high-temperature alloys, primarily used for the purification and homogenization of high-end high-temperature alloy materials such as aero-engine turbine disks, blades, and nuclear industry components. However, white spot defects, a typical metallurgical defect, often appear in the vacuum arc remelting process of high-temperature alloys. This defect significantly reduces the fatigue performance of materials and can even lead to aero-engine disk fracture accidents. It is classified as a "high-risk" quality problem by the industry, and its discovery directly results in product scrapping. Therefore, mitigating the white spot problem in high-temperature alloy vacuum arc remelting ingots and preparing high-temperature alloy arc remelting ingots with low metallurgical defects plays a crucial role in ensuring the performance and use of high-temperature alloys.

[0004] Studies have shown that typical white spot defects are mainly caused by ingot crowns falling into the molten pool without melting. Ingot crowns refer to a layer of metal with a high content of inclusions that forms near the inner wall of the crystallizer around the top ring of a high-temperature alloy vacuum arc remelting ingot, higher than the ingot body. Currently, relevant technical personnel are conducting research on improving the metallurgical defect of white spots in vacuum arc remelting ingots.

[0005] Chinese patent CN119120962A, based on the intrinsic relationship between high-temperature alloy composition, smelting melting rate, and filling ratio, improves the white spot problem of consumable ingots by formulating appropriate melting rates and filling ratios. This patent mainly determines the filling ratio used in vacuum consumable smelting of nickel-based high-temperature alloys based on the determined melting rate in the steady-state smelting stage. Furthermore, this patented technology controls the diameter, i.e., area, of the consumable electrode by controlling the size of the vacuum induction ingot and the amount of ingot peeling, thereby controlling the smelting filling ratio. This ensures that the diameter of the entire consumable electrode is consistent, i.e., the filling ratio is consistent throughout the smelting process, and it has a good white spot control effect on ingots with a certain filling ratio. However, this patent fails to consider that in actual production, both vacuum induction casting ingots and electroslag remelting ingots used as consumable electrodes have a certain taper for demolding. Furthermore, considering the surface quality of the ingots, after peeling, the diameters of the ingots used as consumable electrodes exhibit significant differences between the head and tail. For example, for a Φ508mm ingot, if a Φ440mm vacuum induction or electroslag ingot is used as the consumable electrode, after sawing and peeling, the head and tail diameters can range from approximately 390 to 430mm, resulting in an electrode head-to-tail fill ratio of approximately 0.59 to 0.72 during the smelting process. If the electrodes are uniformly sized through peeling, the ingot yield will decrease significantly. If the electrodes are not uniformly sized through peeling, and constant smelting process parameters are used, white spot defects will appear in areas with larger fill ratios, hindering precise control of white spot defects. Chinese patent CN118086705A calculates the mass ratio of alloy raw materials and impurity raw materials according to the target dirty white spot impurity content requirements, and obtains the dirty white spot defect of GH4169 alloy through composition design and vacuum smelting. It laid the foundation for the research and analysis of dirty white spots, but the patent technology did not study and analyze the control of white spots.

[0006] In summary, current research and achievements regarding the white spot defect in high-temperature alloys still have certain shortcomings. For example, they haven't considered actual production conditions or the impact of significant variations in the filler ratio during the smelting process on white spot formation, particularly the difference in diameter between the head and tail of the consumable electrode. Furthermore, current research hasn't addressed optimizing other smelting process parameters to mitigate the impact of filler ratio variations on white spot formation, thus failing to effectively control white spot formation. Therefore, the aforementioned technologies ultimately cannot solve the white spot defect in high-temperature alloy consumable ingots without sacrificing the yield of consumable electrodes, and thus fail to produce high-temperature alloy products with low metallurgical defects. Summary of the Invention

[0007] The technical problem solved by this invention is to provide a method for preparing high-temperature alloys with low metallurgical defects, which can effectively control white spot defects in high-temperature alloy products.

[0008] In view of this, this application provides a method for preparing a high-temperature alloy with low metallurgical defects, comprising the following steps:

[0009] S1. Preparation of high-temperature alloy consumable electrodes;

[0010] S2. The high-temperature alloy consumable electrode is subjected to vacuum consumable smelting to obtain a high-temperature alloy with low metallurgical defects.

[0011] During the vacuum self-consumption smelting process, the filling ratio gradually decreases during the steady-state smelting stage.

[0012] Based on the filling ratio of the steady-state smelting stage, the smelting melting rate and the number of molten droplets in the steady-state smelting stage are determined accordingly.

[0013] In some specific embodiments, determining the smelting melting rate based on the filling ratio of vacuum consumable smelting specifically means that as the filling ratio gradually decreases from the initial stage to the end stage of the steady-state smelting stage, the smelting melting rate gradually decreases from the initial stage to the end stage of the steady-state smelting stage.

[0014] In some specific embodiments, in the steady-state smelting stage of the vacuum self-consuming smelting, the filling ratio is set as x, the smelting melting rate is set as y, and the numerical relationship between the filling ratio and the smelting melting rate satisfies: y = 4.615x + 0.4769.

[0015] In some specific embodiments, determining the number of molten droplets based on the filling ratio of vacuum consumable smelting specifically means that the filling ratio gradually decreases from the initial stage to the end stage of the steady-state smelting stage, and the number of molten droplets gradually decreases from the initial stage to the end stage of the steady-state smelting stage.

[0016] In some specific embodiments, in the steady-state smelting stage of the vacuum self-consuming smelting, the filling ratio is set as x, the number of smelting droplets is set as z, and the numerical relationship between the filling ratio and the number of smelting droplets satisfies: z = 46.154x - 22.231.

[0017] In some specific embodiments, based on the diameter of the high-temperature alloy consumable electrode with an ingot size of Φ508mm, the smelting filling ratio is 0.67~0.72 and the smelting melting rate is 3.6~3.8kg / min in the initial stage of steady-state smelting, and the smelting filling ratio is 0.59~0.66 and the smelting melting rate is 3.2~3.5kg / min in the final stage of steady-state smelting.

[0018] In some specific embodiments, based on the diameter of the high-temperature alloy consumable electrode with an ingot size of Φ508mm, the smelting filling ratio is 0.67~0.72 and the number of molten droplets is 8.7~11.0 1 / s in the initial stage of steady-state smelting, and the smelting filling ratio is 0.59~0.66 and the number of molten droplets is 5.0~8.2 1 / s in the final stage of steady-state smelting.

[0019] In some specific embodiments, the high-temperature alloy consumable electrode is prepared by vacuum induction smelting or vacuum induction smelting + electroslag remelting.

[0020] This application also provides a high-temperature alloy with low metallurgical defects, which is prepared by the following method:

[0021] S1. Preparation of high-temperature alloy consumable electrodes;

[0022] S2. The high-temperature alloy consumable electrode is subjected to vacuum consumable smelting to obtain a high-temperature alloy with low metallurgical defects.

[0023] During the vacuum self-consumption smelting process, the filling ratio gradually decreases during the steady-state smelting stage.

[0024] Based on the filling ratio of the steady-state smelting stage, the smelting melting rate and the number of molten droplets in the steady-state smelting stage are determined accordingly.

[0025] In some specific embodiments, the high-temperature alloy includes a nickel-based high-temperature alloy.

[0026] This application provides a method for preparing a high-temperature alloy with low metallurgical defects. First, a high-temperature alloy consumable electrode is prepared, and then the high-temperature alloy consumable electrode is subjected to vacuum consumable smelting to obtain a high-temperature alloy with low metallurgical defects. During the vacuum consumable smelting process, the intrinsic relationship between the filling ratio, melting rate, number of molten droplets, and white spots is studied. In actual vacuum consumable smelting processes, where the diameter difference between the head and tail of the high-temperature alloy consumable electrode is large and the filling ratio varies greatly, the method optimizes the number of molten droplets (i.e., the arc length) to control the ingot crown height, enhancing the ingot crown's resistance to inward electromagnetic forces and reducing the risk of ingot crown falling off, thus controlling the formation of white spots at its source. Furthermore, optimizing the melting rate enhances the melting of fallen ingot crowns, further reducing the probability of white spot formation. The preparation method provided in this application can achieve precise control of white spots through the above technical solutions. Compared with existing technologies, this application does not impose high requirements on the diameter range of the head and tail of the consumable electrode (i.e., the uniformity of the electrode rod), does not increase the amount of peeling of the electrode rod, and does not reduce the yield, thus having good practicality. Attached Figure Description

[0027] Figure 1 These are low-magnification photographs of the high-temperature alloys prepared in Example 1 and Comparative Example 1 of the present invention. Detailed Implementation

[0028] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0029] Given the current situation where existing technologies sacrifice the yield of consumable electrode materials to solve white spot defects, this application provides a method for preparing a high-temperature alloy with low metallurgical defects. This method solves the aforementioned problems through the following technical solutions: Based on the diameter of the high-temperature alloy consumable electrode under a certain ingot size, i.e., the smelting filler ratio, the smelting melting rate is determined during the smelting process; with a large filler ratio, a large smelting melting rate is used to enhance the melting of the detached ingot crown and reduce the formation of white spots; with a smaller filler ratio, the ingot crown is less likely to detach, and the probability of white spot formation is lower, so a smaller smelting melting rate is used to reduce the formation of segregation defects; based on the phenomenon of longitudinal heat accumulation in the ingot during vacuum consumable smelting, which easily leads to the formation of longitudinal segregation defects, the entire smelting process adopts a method of gradually decreasing the filler ratio from the initial stage to the end stage of the steady-state smelting phase. That is, the initial stage of steady-state smelting uses smelting at the large end of the consumable electrode, and at a higher melting rate... The smelting process is carried out at a rapid rate, gradually decreasing towards the end of the steady-state smelting stage. At the end of this stage, smelting is performed at the small end of the consumable electrode, with a lower melting rate. Based on the smelting fill ratio, the number of molten droplets (i.e., the smelting arc length) is determined. With a large fill ratio, a larger number of droplets (i.e., a smaller smelting arc length) is used to obtain a short ingot crown, increasing its resistance to inward-pointing electromagnetic forces and reducing the risk of white spots from the ingot crown falling off. With a smaller fill ratio, the ingot crown experiences less inward-pointing electromagnetic force, resulting in a lower risk of crown falling off, allowing for a smaller number of droplets (i.e., a larger smelting arc length) to avoid high molten pool temperatures under shorter arc lengths, which could lead to severe segregation at the A end of the ingot (i.e., the heat-sealed top). Based on the above research, the high-temperature alloy consumable electrode is subjected to vacuum consumable smelting to obtain a low-metallurgical-defect high-temperature alloy without white spot defects. Specifically, this application provides a method for preparing a low-metallurgical-defect high-temperature alloy, including the following steps:

[0030] S1. Preparation of high-temperature alloy consumable electrodes;

[0031] S2. The high-temperature alloy consumable electrode is subjected to vacuum consumable smelting to obtain a high-temperature alloy with low metallurgical defects.

[0032] During the vacuum self-consumption smelting process, the filling ratio gradually decreases during the steady-state smelting stage.

[0033] Based on the filling ratio of the steady-state smelting stage, the smelting melting rate and the number of molten droplets in the steady-state smelting stage are determined accordingly.

[0034] In the preparation method of high-temperature alloys with low metallurgical defects, in step S1, a high-temperature alloy consumable electrode is first prepared. The high-temperature alloy consumable electrode is prepared according to methods well-known to those skilled in the art, such as vacuum induction smelting or vacuum induction smelting combined with electroslag remelting. The above preparation process is carried out according to methods well-known to those skilled in the art, and this application does not impose any particular limitations on it. In the preparation process of the vacuum consumable electrode, the required diameter consumable electrode is prepared by controlling the size of the vacuum induction ingot or electroslag ingot and the amount of ingot peeling. Other relevant parameters can be those commonly used in the art, and this invention will not describe them in detail.

[0035] In step S2, the high-temperature alloy consumable electrode obtained above is subjected to vacuum consumable smelting to obtain a high-temperature alloy with low metallurgical defects, namely, a high-temperature alloy consumable ingot. Defects such as white spots in the vacuum consumable ingot are mainly formed during the vacuum consumable smelting stage, therefore, the process at this stage needs to be controlled.

[0036] Vacuum arc remelting comprises a sequential arc-starting stage, a steady-state remelting stage, and a hot capping stage. The parameters of the steady-state remelting stage significantly influence the metallurgical quality of the arc-remelting ingot. Therefore, this application primarily focuses on the impact of the steady-state remelting stage on metallurgical defects such as white spots during vacuum arc remelting. It should be noted that the steady-state remelting stage has the longest remelting cycle and corresponds to the longest arc-remelting ingot length, accounting for approximately 9 / 11 to 15 / 17 of the ingot length. Conversely, the arc-starting and hot capping stages correspond to the shortest ingot length regions, each accounting for approximately 1 / 17 to 1 / 11 of the ingot length. Because the arc-starting and hot capping stages of arc remelting have short remelting times and correspondingly short molten electrode rod lengths, the initial head-to-tail filling ratio of the arc-remelting electrode can be approximated as the filling ratio of the steady-state remelting stage.

[0037] In the vacuum consumable electrode smelting process, the smelting melting rate is determined based on the diameter of the high-temperature alloy consumable electrode (HTDE) for a specific ingot size (mainly Φ508mm ingot), i.e., the smelting fill ratio. Specifically, HTDEs of different sizes are prepared according to the ingot size of the high-temperature alloy HTDE, such as Φ406mm, Φ508mm, and Φ660mm ingots. During the steady-state smelting stage, the steady-state smelting melting rate is determined based on the diameter of the HTDE's head and tail, i.e., the smelting fill ratio. Specifically, as the smelting fill ratio gradually decreases, the smelting melting rate gradually decreases. More specifically, a large smelting melting rate is used with a large fill ratio to enhance the melting of the detached ingot crown and reduce the formation of white spots. With a smaller fill ratio, the ingot crown is less likely to detach, and the probability of white spot formation is lower, so a smaller smelting melting rate is used to reduce the formation of segregation defects.

[0038] For example, for a Φ508mm high-temperature alloy consumable ingot, when a Φ440mm vacuum induction ingot or electroslag ingot is used as the high-temperature alloy consumable electrode, that is, when the filling ratio of the prepared high-temperature alloy consumable electrode is in the range of 0.59~0.72, the steady-state smelting filling ratio range is 0.59~0.72. The filling ratio gradually decreases in the steady-state smelting stage, and the smelting melting rate range in the steady-state smelting stage decreases with the decrease of the filling ratio, and the smelting melting rate range is 3.2~3.8 kg / min. In some specific embodiments, when the filling ratio gradually decreases from 0.72 to 0.59 in the steady-state smelting stage, the smelting melting rate gradually decreases from 3.8 kg / min to 3.2 kg / min.

[0039] Research shows that during the steady-state smelting stage, the smelting melting rate and the filling ratio exhibit a linear relationship. Specifically, the smelting melting rate is y, and the filling ratio is x. The numerical relationship between the smelting melting rate y and the filling ratio x (regardless of units, considering only the numerical relationship) satisfies: y = 4.615x + 0.4769. The introduction of the above relationship has high accuracy and simplicity. Specifically, in the initial stage of steady-state smelting, the smelting fill ratio is 0.67~0.72, corresponding to a smelting melting rate of 3.6~3.8 kg / min; in the final stage of steady-state smelting, the smelting fill ratio is 0.59~0.66, corresponding to a smelting melting rate of 3.2~3.5 kg / min. More specifically, in the initial stage of steady-state smelting, the smelting fill ratio is 0.72, corresponding to a smelting melting rate of 3.8 kg / min; in the final stage of steady-state smelting, the smelting fill ratio is 0.59, corresponding to a smelting melting rate of 3.2 kg / min. Alternatively, in the initial stage of steady-state smelting, the smelting fill ratio is 0.67, corresponding to a smelting melting rate of 3.6 kg / min; in the final stage of steady-state smelting, the smelting fill ratio is 0.62, corresponding to a smelting melting rate of 3.3 kg / min. It should be noted that during the steady-state smelting stage, the fill ratio gradually decreases from the initial stage to the final stage.

[0040] Studies have found that increasing the smelting rate and enhancing the melting of the ingot crown within the molten pool can reduce white spot defects. Within different smelting filling ratio ranges, if the smelting rate exceeds the upper limit, it will cause the molten pool to become too active, affecting the cleanliness of the ingot. However, when the smelting rate is below the lower limit, the effect on improving white spots is not significant.

[0041] Furthermore, given the longitudinal heat accumulation phenomenon in the ingot during vacuum consumable metallurgy, which easily leads to longitudinal segregation defects, the steady-state smelting stage of the entire process adopts a smelting method where the filling ratio gradually decreases from the initial stage to the final stage. Specifically, the arc-starting stage uses the large end of the consumable electrode for smelting at a higher melting rate, while the hot-sealing stage uses the small end of the consumable electrode for smelting at a lower melting rate to reduce segregation at the ingot head. If the entire smelting process were to use a smelting method where the filling ratio gradually increases from the arc-starting stage to the hot-sealing stage, it would lead to an increased probability of white spots in the later stages of ingot smelting.

[0042] Furthermore, based on the diameter of the consumable electrode of the high-temperature alloy under a certain ingot size, i.e., the smelting fill ratio, the corresponding number of molten droplets (i.e., the arc length) in the smelting process is determined. Specifically, under a large fill ratio, a larger number of molten droplets is used, i.e., a smaller smelting arc length, to obtain a short ingot crown, increase the ingot crown's resistance to inward electromagnetic forces, and reduce the risk of white spots caused by ingot crown falling off; under a small fill ratio, a smaller number of molten droplets is used, i.e., a larger smelting arc length, to avoid high molten pool temperature under small arc length conditions, which would lead to severe segregation at the A end of the ingot (i.e., the heat-sealed top); that is, in the steady-state smelting stage, as the fill ratio gradually decreases, the number of molten droplets also gradually decreases. Through the above technical solutions, precise and effective control of white spots is achieved.

[0043] For example, for a high-temperature alloy consumable ingot with a diameter of Φ508mm, when the filling ratio is in the range of 0.59 to 0.72, from the initial stage to the end stage of steady-state smelting, as the filling ratio gradually decreases, the number of molten droplets used also gradually decreases, and the corresponding number of molten droplets used is 5.0 to 11.0 1 / s; in some specific embodiments, in the steady-state smelting stage, when the filling ratio gradually decreases from 0.72 to 0.59, the number of molten droplets gradually decreases from 11.0 1 / s (shorter arc length) to 5.0 1 / s (longer arc length).

[0044] Research shows that during the steady-state smelting stage, the number of smelting droplets and the filling ratio have a linear relationship. Specifically, the number of smelting droplets is denoted as z, and the filling ratio is denoted as x. The numerical relationship between the number of sub-unit droplets z and the filling ratio x (regardless of units, considering only the numerical relationship) satisfies: z = 46.154x - 22.231. The introduction of the above relationship has high accuracy and simplicity. Specifically, in the initial stage of steady-state smelting, the smelting filling ratio is 0.67~0.72, corresponding to a droplet count of 8.7~11.0 1 / s; in the final stage of steady-state smelting, the smelting filling ratio is 0.59~0.66, corresponding to a droplet count of 5.0~8.21 / s. More specifically, in the initial stage of steady-state smelting, the smelting filling ratio is 0.72, corresponding to a droplet count of 11.0 1 / s; in the final stage of steady-state smelting, the smelting filling ratio is 0.59, corresponding to a droplet count of 5.0 1 / s. Alternatively, in the initial stage of steady-state smelting, the smelting filling ratio is 0.67, corresponding to a droplet count of 8.7 1 / s; in the final stage of steady-state smelting, the smelting filling ratio is 0.62, corresponding to a droplet count of 6.4 1 / s.

[0045] The smelting process provided by this invention adopts a technical solution of gradually decreasing the filling ratio. On this basis, the number of molten droplets is gradually reduced (the arc length is gradually increased). In the early stage of steady-state smelting, a short ingot crown is obtained with a smaller smelting arc length, which enhances the resistance of the ingot crown to electromagnetic forces pointing into the molten pool and reduces the probability of white spot formation. At the same time, in the later stage of steady-state smelting, the molten pool temperature is reduced with a larger arc length, which reduces longitudinal segregation of the ingot. When the number of molten droplets exceeds the upper limit, the risk of droplet short circuit will increase, affecting the smelting stability. When the number of molten droplets exceeds the lower limit, the arc length is larger, which will increase the problem of arc instability.

[0046] It is important to note that during the steady-state smelting stage, the filling ratio gradually decreases from the initial stage to the final stage. The initial stage and the final stage are time points within the steady-state smelting stage. This can be understood as follows: in the vacuum self-consuming smelting process, the arc initiation stage is 0~n min, and the steady-state smelting stage is n+1~m min. Therefore, the initial stage is n+1 min, and the final stage is mmin. During the above steady-state smelting stage, the filling ratio gradually decreases, and correspondingly, the smelting melting rate and the number of molten droplets also gradually decrease.

[0047] In some embodiments, high-temperature alloys (high-temperature alloy consumable ingots) are obtained by vacuum consumable electrode smelting. The specific process includes: placing the consumable electrode into a consumable furnace, closing the furnace door, and starting vacuum evacuation. When the vacuum level and leakage rate meet the requirements (vacuum level < 0.10 Pa, leakage rate < 0.10 Pa / min), power can be supplied to begin melting, entering the arc ignition stage. The arc ignition stage uses current + voltage control, with a current of 4.0 kA to 8.0 kA and a voltage of 21 V to 26 V. The inert gas pressure during the arc ignition period is 0 Pa. The steady-state melting stage uses droplet + melting rate control, with a melting rate range of 3.2 to 3.8 kg / min and a droplet count range of 5.0 to 11.0. During the steady-state melting stage, the inert gas pressure gradually increases from 0 Pa to the pressure used in the steady-state stage, ranging from 400 Pa to 800 Pa. In the hot capping stage, droplet and melting rate control is employed, with a melting rate of 1.4–3.2 kg / min and a droplet size of 11–19 1 / s. During the hot capping stage, both the melting rate and the inert gas pressure gradually decrease from their steady-state values ​​and then remain stable. The inert gas mentioned in this invention can be helium.

[0048] In the vacuum consumable metallurgy process of this application, the smelting rate and the number of molten droplets are optimized according to the change of the filling ratio in the steady-state smelting stage. While avoiding segregation defects, the white spots of high-temperature alloys can be effectively controlled.

[0049] The present invention provides a method for preparing high-temperature alloys with low metallurgical defects. This method includes obtaining high-temperature alloys with low metallurgical defects by using a duplex or triple melting process. For example, high-temperature alloy consumable ingots are obtained by using vacuum induction smelting + vacuum arc remelting; or high-temperature alloy consumable ingots are obtained by using vacuum induction smelting + electroslag remelting + vacuum arc remelting. In the process of vacuum arc remelting, by mastering the intrinsic relationship between the filling ratio, the number of molten droplets (i.e., arc length), the melting rate and white spot defects, the white spot defects in the ingots can be effectively controlled in the vacuum arc remelting process of high-temperature alloys without imposing high requirements on the consistency of the head and tail of the consumable electrode or sacrificing the electrode yield.

[0050] This application also provides a high-temperature alloy with low metallurgical defects, which is prepared by the following method:

[0051] S1. Preparation of high-temperature alloy consumable electrodes;

[0052] S2. The high-temperature alloy consumable electrode is subjected to vacuum consumable smelting to obtain a high-temperature alloy with low metallurgical defects.

[0053] During the vacuum self-consumable smelting process, from the arc initiation stage to the hot capping stage, the filling ratio gradually decreases.

[0054] Based on the filling ratio of vacuum consumable metallurgy, the smelting rate and the number of molten droplets are determined accordingly.

[0055] The high-temperature alloys involved in this application are well known to those skilled in the art; for example, the high-temperature alloys include nickel-based high-temperature alloys.

[0056] To further understand the present invention, the following detailed description of the low-metallurgical-defect high-temperature alloy and its preparation method provided by the present invention is provided in conjunction with the embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0057] Example 1

[0058] ① The chemical composition of the nickel-based high-temperature alloy used, in mass percentage, is as follows: C: 0.03~0.08%, Cr: 19~22%, Al: 0.6~1.0%, Ti: 2.4~2.8%, Fe≤4.0%, with the balance being Ni and unavoidable impurity elements and trace amounts of Mn, Si, P, B, etc. For the Φ508mm consumable ingot shape, a Φ440mm vacuum induction ingot is used as the consumable electrode. The vacuum induction ingot is processed through several steps such as sawing, peeling, baking and welding to obtain a consumable electrode rod with a filling ratio of 0.59~0.72. The diameter of the smelting electrode rod gradually decreases from the large end to the small end, that is, the filling ratio gradually decreases from 0.72 at the large end to 0.59 at the small end.

[0059] ② The electrode rod from step ① is placed into a Φ508mm ingot-shaped consumable furnace as a consumable electrode. The furnace door is closed, and vacuuming begins. When the vacuum degree and leakage rate meet the requirements (vacuum degree < 0.1 Pa, leakage rate < 0.1 Pa / min), power can be supplied to start melting. The entire smelting process is carried out with the large end of the electrode facing down, that is, the filling ratio gradually decreases during the smelting process. The arc-starting stage of consumable smelting is from 0 to 25 minutes. The arc-starting stage is controlled by current and voltage. The current range of the arc-starting stage is 5.0kA to 8.0kA, and the voltage range is 22V to 26V. The helium pressure during the arc-starting stage is 0Pa.

[0060] ③ The steady-state smelting stage of self-consumption smelting is from 26 to 490 minutes. During the steady-state smelting stage, droplet and melting rate control is adopted. The melting rate ranges from 3.2 to 3.8 kg / min, and the number of droplets ranges from 5 to 11 1 / s. As the smelting filling ratio gradually decreases from 0.72 in the initial stage of steady state to 0.59 in the final stage of steady state, the smelting melting rate gradually decreases from 3.8 kg / min in the initial stage of steady state to 3.2 kg / min in the final stage of steady state, and the number of droplets gradually decreases from 11.0 1 / s in the initial stage of steady state to 5.0 1 / s in the final stage of steady state.

[0061] Helium was introduced when the steady-state smelting time reached 100 min, and the helium pressure increased to 500 Pa after the smelting time reached 150 min and then tended to stabilize.

[0062] ④ The period from 491 to 550 minutes is the hot capping stage of self-consumption smelting. The hot capping stage adopts droplet + melting rate control, with the number of droplets being 11~17 1 / s and the melting rate being 1.4~3.2 kg / min;

[0063] The period from 491 to 510 minutes is the early stage of hot capping smelting, during which the melting rate gradually decreases from 3.2 kg / min to 1.7 kg / min, and the helium pressure used decreases from 500 Pa to 200 Pa. The period from 511 to 550 minutes is the late stage of hot capping smelting, during which the melting rate gradually decreases from 1.7 kg / min to 1.4 kg / min, and the helium pressure used is 200 Pa.

[0064] ⑤ After the hot capping is completed, the ingot is cooled in the crystallizer for 90 minutes and then removed from the ingot. After air cooling, a consumable ingot is obtained.

[0065] The high-temperature alloy consumable ingots obtained by the above method are free of white spot defects.

[0066] Example 2

[0067] The only difference from Example 1 is that a consumable electrode with a smelting filling ratio of 0.62~0.67 was prepared. The filling ratio gradually decreased from 0.67 in the initial stage to 0.62 in the final stage during the entire steady-state smelting process. The smelting melting rate gradually decreased from 3.6 kg / min in the initial stage to 3.3 kg / min in the final stage. The number of smelting droplets gradually decreased from 8.7 1 / s in the initial stage to 6.4 1 / s in the final stage.

[0068] No white spot defects were observed in the high-temperature alloy consumable ingots obtained using the above method.

[0069] Example 3

[0070] The only difference from Example 1 is that the high-temperature alloy consumable electrode prepared has the following composition: C: 0.03~0.1%, Cr: 18~21%, Co: 12~15%, Mo: 3.5~5%, Al: 1.2~1.6%, Ti: 2.75~3.25%, Fe≤2.0%, B: 0.003~0.01%, Zr: 0.02~0.08%, with the balance being Ni and unavoidable impurity elements;

[0071] The filling ratio of the high-temperature alloy consumable electrode is 0.59~0.67. During the entire steady-state smelting process, the filling ratio gradually decreases from 0.67 in the initial stage to 0.59 in the final stage. The smelting melting rate gradually decreases from 3.6 kg / min in the initial stage to 3.2 kg / min in the final stage. The number of molten droplets gradually decreases from 8.7 / s in the initial stage to 5.0 / s in the final stage.

[0072] No white spot defects were observed in the high-temperature alloy consumable ingots obtained using the above method.

[0073] Comparative Example 1

[0074] The only difference from Example 1 is that the arc initiation stage of the self-consumable smelting process uses the small end of the self-consumable electrode for smelting, the hot capping stage uses the large end of the self-consumable electrode for smelting, the smelting filling ratio gradually increases from 0.59 to 0.72 throughout the smelting process, the smelting melting rate used in the steady-state smelting stage is 3.2 kg / min, and the smelting droplet number is 6 1 / s.

[0075] In this comparative example, as vacuum consumable metallurgy proceeds, white spot defects are generated under constant smelting rate and number of molten droplets.

[0076] This invention analyzes the low-magnification properties of the high-temperature alloys prepared in Example 1 and Comparative Example 1, such as... Figure 1 As shown, by Figure 1 It can be seen that, compared with Comparative Example 1, the high-temperature alloy obtained in Example 1 has no white spot defects at low magnification.

[0077] Comparative Example 2

[0078] The only difference from Example 1 is that the melting rate in the initial stage of steady-state smelting is 4.0 kg / min.

[0079] During the preparation of the aforementioned consumable ingots, the molten pool was too active in the initial stage of smelting, which affected the cleanliness of the molten pool.

[0080] Comparative Example 3

[0081] The only difference from Example 1 is that the melting rate at the end of the steady-state smelting stage is 3.0 kg / min.

[0082] During the preparation of the aforementioned consumable ingot, the molten pool did not reach the edge at the end of the steady-state smelting process, resulting in poor surface quality of the ingot. At the same time, the molten pool was shallow, making it difficult to melt off the electrode and ingot crown, and white spots formed.

[0083] Comparative Example 4

[0084] The only difference from Example 1 is that the number of molten droplets in the initial stage of steady-state smelting is 12 1 / s.

[0085] In the above-mentioned process of preparing consumable ingots, the initial process of steady-state smelting carries a high risk of arc short circuit, which affects the stability of the smelting process and leads to the formation of white spots.

[0086] Comparative Example 5

[0087] The only difference from Example 1 is that the number of molten droplets in the final stage of steady-state smelting is 4 1 / s.

[0088] During the preparation of the aforementioned consumable ingot, the arc length of the electric arc increases significantly at the end of the steady-state smelting process, and the electric arc is prone to instability, resulting in significant white spot defects.

[0089] Comparative Example 6

[0090] The only difference from Example 1 is that the steady-state smelting droplet number range is 7~9 1 / s, that is, the droplet number gradually decreases from 9 1 / s to 7 1 / s from the initial stage of steady-state smelting to the end of steady-state smelting.

[0091] In the above-mentioned process of preparing consumable ingots, the number of molten droplets is relatively small and the smelting arc length is large in the initial stage of smelting, which leads to an increase in the electromagnetic force on the ingot crown pointing into the molten pool, making the ingot crown easy to fall off and produce white spots; in the final stage of smelting, the number of molten droplets is relatively large and the smelting arc length is small, which results in a higher molten pool temperature, which is not conducive to the control of segregation at the head of the consumable ingot.

[0092] Comparative Example 7

[0093] The only difference from Example 1 is that the steady-state smelting melting rate range is 3.4~3.6 kg / min, that is, the melting rate used from the initial stage of steady-state smelting to the end of steady-state smelting gradually decreases from 3.6 kg / min to 3.4 kg / min.

[0094] In the above-mentioned process of preparing consumable ingots, the melting rate is relatively low in the initial stage of smelting, resulting in a shallow smelting pool, which is not conducive to the melting of the ingot crown falling into the smelting pool. Under this condition, white spot defects appear at the end of the obtained consumable ingot. At the same time, the melting rate is relatively high in the final stage of smelting, resulting in a deeper smelting pool, which will cause the formation of segregation at the head of the consumable ingot.

[0095] As can be seen from the above embodiments, the high-temperature alloy with low metallurgical defects and its preparation method provided by the present invention, by studying the intrinsic relationship between filling ratio, arc length, melting rate and white spot defects, can prepare high-temperature alloy products without white spot metallurgical defects without imposing high requirements on the consistency of the self-consumable electrode head and tail or sacrificing the electrode yield, thereby reducing the risk of high-temperature alloy products being scrapped.

[0096] Since the formation of white spots on high-temperature alloy consumable ingots mainly occurs during the smelting stage, and is primarily affected by the filling ratio, arc length, and melting rate, other relevant parameters for vacuum consumable smelting can be those commonly used in the field, and this invention does not impose any special limitations on them.

[0097] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0098] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a high-temperature alloy with low metallurgical defects, comprising the following steps: S1. Preparation of high-temperature alloy consumable electrodes; S2. The high-temperature alloy consumable electrode is subjected to vacuum consumable smelting to obtain a low-metallurgical-defect high-temperature alloy with controlled white spot defects. During the vacuum self-consumption smelting process, the filling ratio gradually decreases during the steady-state smelting stage. Based on the filling ratio of the steady-state smelting stage, the smelting melting rate and the number of molten droplets in the steady-state smelting stage are determined accordingly. In the steady-state smelting stage of the vacuum self-consumable smelting, the filling ratio is set as x, the smelting melting rate is set as y, and the numerical relationship between the filling ratio and the smelting melting rate satisfies: y = 4.615x + 0.4769. In the steady-state smelting stage of the vacuum self-consuming smelting, the filling ratio is set as x, the number of smelting droplets is set as z, and the numerical relationship between the filling ratio and the number of smelting droplets satisfies: z = 46.154x - 22.

231.

2. The preparation method according to claim 1, characterized in that, The determination of the smelting melting rate based on the filling ratio of vacuum self-consumable smelting is specifically as follows: if the filling ratio gradually decreases from the initial stage to the end stage of the steady-state smelting stage, then the smelting melting rate gradually decreases from the initial stage to the end stage of the steady-state smelting stage.

3. The preparation method according to claim 1 or 2, characterized in that, The determination of the number of molten droplets in the vacuum self-consumable smelting process based on the filling ratio is specifically as follows: the filling ratio gradually decreases from the initial stage to the end stage of the steady-state smelting process, and the number of molten droplets in the process gradually decreases from the initial stage to the end stage of the steady-state smelting process.

4. The preparation method according to claim 1, characterized in that, Based on the diameter of the consumable electrode for high-temperature alloys with an ingot size of Φ508mm, the smelting filling ratio is 0.67~0.72 and the smelting melting rate is 3.6~3.8kg / min in the initial stage of steady-state smelting, and the smelting filling ratio is 0.59~0.66 and the smelting melting rate is 3.2~3.5kg / min in the final stage of steady-state smelting.

5. The preparation method according to claim 1, characterized in that, Based on the diameter of the consumable electrode for high-temperature alloys with an ingot size of Φ508mm, the smelting filling ratio is 0.67~0.72 and the number of molten droplets is 8.7~11.0 1 / s in the initial stage of steady-state smelting, and the smelting filling ratio is 0.59~0.66 and the number of molten droplets is 5.0~8.2 1 / s in the final stage of steady-state smelting.

6. The preparation method according to any one of claims 1 to 2, characterized in that, The high-temperature alloy consumable electrode is prepared by vacuum induction smelting or vacuum induction smelting + electroslag remelting.

7. A high-temperature alloy with low metallurgical defects for controlling white spot defects, prepared according to the following method: S1. Preparation of high-temperature alloy consumable electrodes; S2. The high-temperature alloy consumable electrode is subjected to vacuum consumable smelting to obtain a high-temperature alloy with low metallurgical defects. During the vacuum self-consumption smelting process, the filling ratio gradually decreases during the steady-state smelting stage. Based on the filling ratio of the steady-state smelting stage, the smelting melting rate and the number of molten droplets in the steady-state smelting stage are determined accordingly. In the steady-state smelting stage of the vacuum self-consumable smelting, the filling ratio is set as x, the smelting melting rate is set as y, and the numerical relationship between the filling ratio and the smelting melting rate satisfies: y = 4.615x + 0.4769. In the steady-state smelting stage of the vacuum self-consuming smelting, the filling ratio is set as x, the number of smelting droplets is set as z, and the numerical relationship between the filling ratio and the number of smelting droplets satisfies: z = 46.154x - 22.

231.

8. The high-temperature alloy according to claim 7, characterized in that, The high-temperature alloy includes nickel-based high-temperature alloys.

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