A high-density high-temperature alloy and its preparation method

Abstract

This invention relates to the field of high-temperature alloy technology, and provides a highly dense high-temperature alloy and its preparation method. The preparation method of the highly dense high-temperature alloy includes the following steps: S1 preparing a high-temperature alloy vacuum consumable electrode rod; S2 subjecting the high-temperature alloy vacuum consumable electrode rod to vacuum consumable smelting; during the vacuum consumable smelting process, determining the range of melting rate reduction in the later stage of steady-state smelting based on the ingot size and alloy type of the high-temperature alloy; determining the range of melting rate reduction in the early stage of hot-sealing smelting based on the ingot size of the high-temperature alloy; and determining the smelting time in the later stage of hot-sealing smelting based on the size and alloy type of the high-temperature alloy. The preparation method provided by this application solves the problem of controlling shrinkage cavities in high-temperature alloys with different ingot sizes and alloy types, and prepares highly dense high-temperature alloy products.

Description

Technical Field

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

[0002] High-temperature alloys are a class of metallic materials that can operate stably for extended periods in high-temperature (typically above 600°C) environments, under severe stress, corrosion, and oxidation. Due to their excellent overall performance, high-temperature alloys are widely used in key fields such as aerospace, energy, and chemical engineering, for example, in aircraft engine turbine blades, gas turbine hot-end components, and nuclear reactor materials.

[0003] Currently, high-quality high-temperature alloys all employ vacuum arc remelting (VAR) as a secondary smelting process. Numerous studies have found that VAR has a significant impact on the quality and yield of high-temperature alloy products. For example, after VAR remelting, the ingots are prone to shrinkage cavities. Large shrinkage cavities can lead to cracking during subsequent hot working, severely affecting product quality and yield. Furthermore, deeper and larger shrinkage cavities result in larger material removal during subsequent hot working, significantly reducing yield and increasing production costs. Therefore, mitigating or eliminating shrinkage defects in vacuum arc remelting ingots to obtain highly dense high-temperature alloy products is crucial for the manufacturing and development of high-temperature alloys.

[0004] To address the shrinkage cavity problem in vacuum consumable ingots, Chinese patent CN116851667A proposes determining the weight and time of the feeding electrode based on the feeding requirements of titanium alloys. Setting the feeding electrode weight to 10%~20% of the total weight of the melting electrode and the feeding time to 25%~35% of the total melting time can significantly reduce the shrinkage cavity size. Chinese patent CN117892371A provides a hot-air blasting process and method for reducing the depth of shrinkage cavities in vacuum consumable ingot melting, and also optimizes the smelting rate and time in the hot capping process to alleviate the shrinkage cavity problem. However, the above patents' solutions to the shrinkage cavity problem only focus on optimizing the process parameters in the hot capping stage. This results in a long hot capping process time, a large amount of alloy used for feeding, and a longer unstable microstructure region in the hot capping stage. For high-quality high-temperature alloys, it is necessary to remove these unstable microstructure regions.

[0005] In summary, current technologies have been used to improve the shrinkage cavity problem of vacuum consumable ingots, but the research and results are still insufficient, and the control of shrinkage cavity in high-temperature alloy consumable ingots of different ingot types and alloy types has not been addressed. Summary of the Invention

[0006] The technical problem solved by this invention is to provide a method for preparing a highly dense high-temperature alloy. The high-temperature alloy prepared by this application can achieve effective control of shrinkage cavities.

[0007] In view of this, this application provides a method for preparing a highly dense high-temperature alloy, comprising the following steps:

[0008] S1. Preparation of high-temperature alloy vacuum consumable electrode rod;

[0009] S2. The high-temperature alloy vacuum consumable electrode rod is subjected to vacuum consumable smelting.

[0010] During the vacuum arc remelting process, the range of melting rate reduction in the later stage of steady-state smelting is determined based on the ingot size and alloy type of the high-temperature alloy.

[0011] Based on the ingot dimensions of the high-temperature alloy, determine the range of melting rate reduction during the early stage of hot capping smelting;

[0012] The smelting time in the later stage of hot capping smelting is determined based on the ingot size and alloy type of the high-temperature alloy.

[0013] In some specific embodiments, the dimensions of the high-temperature alloy include at least one of Φ406mm, Φ508mm, and Φ660mm.

[0014] In some specific embodiments, the alloy type of the high-temperature alloy includes low-expansion high-temperature alloys and other high-temperature alloys, wherein the low-expansion high-temperature alloy is selected from one or more of GH2907, GH2909 and GH6387.

[0015] In some specific embodiments, the ingot size of the high-temperature alloy is Φ406mm. During the later stage of steady-state smelting, the melting rate decreases by (0~0.2] kg / min 40~80min before the hot capping smelting; during the early stage of hot capping smelting, the melting rate decreases by 1.2~1.5 kg / min 20~30min; and during the later stage of hot capping smelting, the low melting rate smelting time is 15~30min.

[0016] In some specific embodiments, the high-temperature alloy is a low-expansion high-temperature alloy, and the melting rate is reduced by (0~0.1] kg / min in the first 40~80 min of the deheating capping smelting, and the low melting rate smelting time in the later stage of the hot capping smelting is [15~20) min; the high-temperature alloy is other types of high-temperature alloy, and the melting rate is reduced by 0.1~0.2 kg / min in the first 40~80 min of the deheating capping smelting, and the low melting rate smelting time in the later stage of the hot capping smelting is 20~30 min.

[0017] In some specific embodiments, the ingot size of the high-temperature alloy is Φ508mm. During the later stage of steady-state smelting, the melting rate decreases by 0.2-0.5 kg / min 90-180 min before the hot capping smelting; during the early stage of hot capping smelting, the melting rate decreases by 1.5-1.8 kg / min 20-30 min; and during the later stage of hot capping smelting, the low melting rate smelting time is 25-40 min.

[0018] In some specific embodiments, the high-temperature alloy is a low-expansion high-temperature alloy, the melting rate is reduced by [0.2~0.3) kg / min in the first 90~180 min of the deheating capping smelting, and the low melting rate smelting time in the later stage of the hot capping smelting is [25~30) min; the high-temperature alloy is other types of high-temperature alloy, the melting rate is reduced by 0.3~0.5 kg / min in the first 90~180 min of the deheating capping smelting, and the low melting rate smelting time in the later stage of the hot capping smelting is 30~40 min.

[0019] In some specific embodiments, the high-temperature alloy has a size of Φ660mm. During the later stage of steady-state smelting, the melting rate decreases by 0.4-0.7 kg / min in the 190-300 min before the hot capping smelting; during the early stage of hot capping smelting, the melting rate decreases by 1.7-2.0 kg / min in the 20-30 min; and during the later stage of hot capping smelting, the low melting rate smelting time is 35-65 min.

[0020] In some specific embodiments, the high-temperature alloy is a low-expansion high-temperature alloy, and the melting rate is reduced by [0.4~0.5) kg / min in the first 190~300 min of the deheating capping smelting, and the low melting rate smelting time in the later stage of the hot capping smelting is [35~45) min; the high-temperature alloy is other types of high-temperature alloy, and the melting rate is reduced by 0.5~0.7 kg / min in the first 190~300 min of the deheating capping smelting, and the low melting rate smelting time in the later stage of the hot capping smelting is 45~65 min.

[0021] This application provides a high-density high-temperature alloy prepared by the aforementioned preparation method, wherein the shrinkage depth of the high-density high-temperature alloy is 30~80mm.

[0022] This application provides a method for preparing a highly dense high-temperature alloy. First, a high-temperature alloy vacuum consumable electrode rod is prepared. Then, the high-temperature alloy vacuum consumable electrode rod is subjected to vacuum consumable smelting. During the vacuum consumable smelting process, by studying and controlling the intrinsic relationship between the ingot size, alloy type, steady-state smelting, hot capping smelting, and shrinkage cavity of the high-temperature alloy consumable ingot in stages, effective control of shrinkage cavities for different ingot sizes and types of high-temperature alloys is achieved, resulting in a highly dense high-temperature alloy product. Furthermore, by simultaneously optimizing the steady-state smelting and hot capping smelting processes, this application effectively reduces the shrinkage cavity size without increasing the amount of alloy used for feeding, without increasing the length of the unstable microstructure region in the hot capping smelting, and without increasing the amount of material cut off from the high-temperature alloy product. Attached Figure Description

[0023] Figure 1 Photographs showing the shrinkage cavities of the high-temperature alloy consumable ingots prepared in Example 2(a) and Comparative Example 1(b) of the present invention;

[0024] Figure 2 Photograph (a) shows the location and depth of the shrinkage cavity center obtained from the experimental dissection of the high-temperature alloy consumable ingot prepared in Example 2 of the present invention, and photograph (b) shows the location and depth of the shrinkage cavity center obtained from the simulation prediction of the high-temperature alloy consumable ingot prepared in Example 2. Detailed Implementation

[0025] 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.

[0026] Given the existing technology's need for controlling shrinkage cavities in high-temperature alloy vacuum consumable ingots to obtain highly dense high-temperature alloy consumable ingot products, this application studies shrinkage cavity control in vacuum consumable smelting. Generally, hot-sealing smelting differs significantly from steady-state smelting. Compared to steady-state smelting, hot-sealing smelting involves greater variations in key parameters such as melting rate, leading to unstable hot-sealing microstructures. These unstable microstructures affect the performance of subsequently hot-processed products. Therefore, it is necessary to remove these unstable hot-sealing consumable ingot microstructures as much as possible on the production site. Thus, in actual vacuum consumable smelting, the shrinkage cavity size of the consumable ingot should be minimized during hot-sealing smelting, while simultaneously avoiding increasing the length of unstable microstructure regions; that is, the amount of alloy kilograms used for feeding must be controlled. Therefore, in the vacuum consumable smelting process, the shrinkage cavity of the consumable ingot is mainly related to the ingot shape, alloy type, and melting parameters. Therefore, this invention, based on the ingot size and alloy type of different high-temperature alloy consumable ingots, determines the range of melting rate reduction in the later stage of steady-state smelting in vacuum consumable smelting. Simultaneously, based on the ingot size of the high-temperature alloy, it determines the range of melting rate reduction in the early stage of hot capping smelting in vacuum consumable smelting. Furthermore, based on the above, and considering the ingot size and alloy type of the high-temperature alloy consumable ingot, it determines the low-melting-rate smelting time in the later stage of hot capping smelting in vacuum consumable smelting. This effectively controls the shrinkage cavity of high-temperature alloy consumable ingots, solving the problem of shrinkage cavity control for high-temperature alloy consumable ingots of different sizes and alloy types, and producing highly dense high-temperature alloy products. Specifically, this invention discloses a method for preparing highly dense high-temperature alloys, including the following steps:

[0027] S1. Preparation of high-temperature alloy vacuum consumable electrode rod;

[0028] S2. The high-temperature alloy vacuum consumable electrode rod is subjected to vacuum consumable smelting.

[0029] In the vacuum arc remelting process, the range of melting rate reduction in the later stage of steady-state smelting is determined based on the ingot size and alloy type of the high-temperature alloy.

[0030] Based on the ingot dimensions of the high-temperature alloy, determine the range of melting rate reduction during the early stage of hot capping smelting;

[0031] The smelting time in the later stage of hot capping smelting is determined based on the ingot size and alloy type of the high-temperature alloy.

[0032] In this application, the high-temperature alloy vacuum consumable electrode rod can be obtained by vacuum induction smelting casting or electroslag remelting smelting, and the high-temperature alloy consumable ingot obtained by vacuum consumable smelting is the high-temperature alloy product described in this application.

[0033] First, based on the ingot size and alloy type of the high-temperature alloy consumable ingot, the range of melting rate reduction in the later stages of steady-state smelting in vacuum consumable smelting is determined. This avoids excessive melting rate reduction in small ingots, which increases the smelting cycle and production costs; while insufficient melting rate reduction in large ingots makes it difficult to effectively reduce the molten pool size before the hot capping period. Simultaneously, for the same ingot size, the problem of increased smelting cycle due to a small tendency for shrinkage cavities in low-expansion high-temperature alloys being less susceptible to this issue, while the problem of increased shrinkage cavities due to a large melting rate reduction in other high-temperature alloys being less susceptible to this issue, makes it difficult to reduce the molten pool size before the hot capping period. Furthermore, based on different ingot sizes, the range of melting rate reduction in the early stages of hot capping smelting for the aforementioned high-temperature alloy is determined. This avoids the problem of a large and rapid melting rate reduction in the early stages of hot capping for small ingots, which reduces arc stability; and also avoids the problem of a small and slow melting rate reduction in the early stages of hot capping for large ingots, resulting in small molten pool shrinkage and unsatisfactory feeding effects. Finally, based on the ingot size and alloy type of the consumable ingot, the low melting rate smelting time of the high-temperature alloy in the later stage of hot capping smelting in vacuum consumable smelting is determined. This avoids the problems of long feeding time, long production cycle and long unstable microstructure region of small ingots and low expansion high-temperature alloys; at the same time, it avoids the problems of short feeding time, poor feeding effect and large shrinkage cavity size of large ingots and other high-temperature alloys.

[0034] Therefore, this invention provides a method for preparing highly dense high-temperature alloys (high-temperature alloy consumable ingots). By clarifying the intrinsic relationship between ingot size, alloy type, steady-state smelting process, hot capping smelting process and shrinkage cavity of consumable ingots, it achieves effective control of shrinkage cavity defects in vacuum consumable ingots of different ingot types and types, and prepares highly dense high-temperature alloy consumable ingot products.

[0035] In the vacuum consumable smelting production site, different ingot sizes and different types of high-temperature alloys tend to form shrinkage cavities of different sizes. The corresponding smelting processes should be different. It is necessary to formulate reasonable steady-state smelting processes and hot capping smelting processes to achieve effective control of shrinkage cavities in consumable ingots of different sizes and alloy types.

[0036] Based on the above, the preparation method is explained in detail below:

[0037] This application first prepares a high-temperature alloy vacuum consumable metallurgical electrode rod. The preparation method of the high-temperature alloy vacuum consumable metallurgical electrode rod can be carried out in accordance with the methods known to those skilled in the art, and this application does not impose any special restrictions on it.

[0038] According to the present invention, the prepared high-temperature alloy vacuum consumable metallization electrode rod is then subjected to vacuum consumable metallization. In this application, the vacuum consumable metallization includes an arc-starting stage, a steady-state metallization stage, and a hot-sealing metallization stage performed sequentially. Except for the following process adjustments, other process methods are carried out in a manner known to those skilled in the art, and this application does not impose any special restrictions on them.

[0039] In the process of vacuum consumable metallurgy, the high-temperature alloy vacuum consumable electrode rod is first brought into the arc-starting stage. The arc-starting stage is carried out in a manner known to those skilled in the art, and this application does not impose any special restrictions on it.

[0040] During the steady-state smelting stage, the range of melting rate reduction in the later stages of steady-state smelting is determined based on the ingot size and alloy type of the high-temperature alloy. Specifically, the high-temperature alloy consumable ingots of different sizes include at least one of Φ406mm, Φ508mm, and Φ660mm. In a specific embodiment, the high-temperature alloy consumable ingots of different sizes include Φ406mm, Φ508mm, or Φ660mm. In this application, the ingot size of the high-temperature alloy refers to different diameter dimensions of the consumable ingot. The type of high-temperature alloy includes low-expansion high-temperature alloys and other high-temperature alloys, wherein the low-expansion high-temperature alloys include at least one of GH2907, GH2909, and GH6387.

[0041] Based on the determination of the ingot size and alloy type of the aforementioned high-temperature alloy, the range of melting rate reduction during the later stage of steady-state smelting in vacuum consumable smelting is determined. The early-stage steady-state smelting process is carried out in a manner well known to those skilled in the art, and this application does not impose any special restrictions on it. Specifically, when the ingot size is Φ406mm, the melting rate reduction range during the later stage of steady-state smelting (the melting rate begins to decrease 40-80 minutes before the capping stage) is (0-0.2] g / min; when the alloy type is a low-expansion high-temperature alloy, the melting rate reduction range during the later stage of steady-state smelting is (0-0.1] kg / min; when the alloy type is other high-temperature alloys, the melting rate reduction range during the later stage of steady-state smelting is 0.1-0.2 kg / min.

[0042] When the ingot size is Φ508mm, the melting rate decreases by 0.2~0.5 kg / min during the later stages of self-consumption steady-state smelting (90~180 min before the final capping smelting). Specifically, when the alloy type is a low-expansion high-temperature alloy, the melting rate decreases by [0.2~0.3] kg / min during the later stages of self-consumption steady-state smelting; when the alloy type is another high-temperature alloy, the melting rate decreases by 0.3~0.5 kg / min during the later stages of self-consumption steady-state smelting. Specifically, the melting rate decreases at 100, 110, 120, 130, 140, 150, 160, or 170 min before the final capping smelting; when the alloy type is another high-temperature alloy, the melting rate decreases by 0.3 kg / min, 0.4 kg / min, or 0.5 kg / min during the later stages of self-consumption steady-state smelting.

[0043] When the ingot shape is Φ660mm, the melting rate decreases by 0.4~0.7 kg / min during the later stages of self-consumption steady-state smelting (the melting rate begins to decrease 190~300 min before the capping process). Specifically, when the alloy type is a low-expansion high-temperature alloy, the melting rate decreases by [0.4~0.5] kg / min during the later stages of self-consumption steady-state smelting; when the alloy type is another high-temperature alloy, the melting rate decreases by 0.5~0.7 kg / min during the later stages of self-consumption steady-state smelting. Specifically, the melting rate decreases at 200, 210, 230, 250, 260, 270, 280, or 290 min before the capping process; when the alloy type is another high-temperature alloy, the melting rate decreases by 0.5 kg / min, 0.6 kg / min, or 0.7 kg / min during the later stages of self-consumption steady-state smelting.

[0044] In the later stages of vacuum consumable solid-state smelting, reducing the melting rate effectively decreases the molten pool volume at the start of hot capping smelting, laying a good foundation for shortening the hot capping time and reducing the amount of alloy required for replenishment. Simultaneously, considering that larger ingot sizes result in larger molten pool sizes, longer hot capping molten pool shrinkage times, and larger replenishment quantities, the invention proposes that the melting rate reduction range should increase with increasing ingot size. Furthermore, this invention considers that, for a given ingot size, the type of high-temperature alloy affects shrinkage cavities. For example, generally, low-expansion high-temperature alloys experience less alloy shrinkage during cooling, resulting in smaller shrinkage cavities, while other high-temperature alloys generally experience greater alloy shrinkage during cooling, resulting in larger shrinkage cavities. Therefore, for the same ingot size, a smaller melting rate reduction range is used for low-expansion high-temperature alloys to avoid significantly affecting the smelting cycle; while a larger melting rate reduction range is used for other alloys to effectively reduce the melting rate in the early stages of hot capping, laying the foundation for effective molten pool shrinkage during hot capping and controlling the amount of alloy required for replenishment. If the melting rate decreases beyond the specified range for different ingot shapes and different types of high-temperature alloys, it will result in a long smelting cycle; while if the melting rate decreases below the specified range, it will be difficult to effectively reduce the volume of the molten pool at the beginning of hot capping and reduce the feeding effect.

[0045] According to some embodiments of the present invention, based on different consumable ingot sizes, the range of melting rate decrease in the high-temperature alloy during the early stage of vacuum consumable capping smelting includes:

[0046] When the self-consumable ingot is Φ406mm, during the vacuum self-consumable smelting and hot capping process, the smelting rate is reduced by 1.2-1.5 kg / min within 20-30 minutes, i.e., in the early stage of hot capping smelting; specifically, the smelting rate is reduced by 1.3 kg / min, 1.4 kg / min, or 1.5 kg / min in the first 21, 23, 24, 26, 28, or 29 minutes of hot capping smelting.

[0047] When the self-consumable ingot is Φ508mm, during the vacuum self-consumable smelting hot capping period, the smelting melting rate is reduced by 1.5-1.8 kg / min within 20-30 minutes, i.e., the early stage of hot capping smelting; specifically, the smelting melting rate is reduced by 1.6 kg / min, 1.7 kg / min, or 1.8 kg / min in the first 21, 23, 24, 26, 28, or 29 minutes of hot capping smelting.

[0048] When the self-consumable ingot is Φ660mm, during the vacuum self-consumable smelting hot capping period, the smelting melting rate is reduced by 1.7-2.0 kg / min within 20-30 minutes, i.e., the early stage of hot capping smelting; specifically, the smelting melting rate is reduced by 1.8 kg / min, 1.9 kg / min, or 2.0 kg / min in the first 21, 23, 24, 26, 28, or 29 minutes of hot capping smelting.

[0049] In this invention, as the ingot size increases, the rate of decrease in melting speed during the early stage of hot capping smelting is appropriately increased. This solves the problems of large and rapid melting speed decrease in the early stage of hot capping for small consumable ingots, which reduces arc stability. Simultaneously, it addresses the problems of small and slow melting speed decrease in the early stage of hot capping for large consumable ingots, resulting in small molten pool shrinkage and unsatisfactory feeding effect. If the melting speed decrease range exceeds the specified range during the early stage of hot capping smelting of high-temperature alloys of different ingot sizes, it may lead to problems such as arc instability; while if the melting speed decrease range is below the specified range, it is difficult to effectively control molten pool shrinkage and feeding effect.

[0050] Furthermore, based on the ingot size and alloy type of the high-temperature alloy consumable ingot, the low-melting-rate smelting time in the later stage of hot capping smelting for the high-temperature alloy vacuum consumable smelting is determined to include:

[0051] When the ingot shape is Φ406mm, the low-melting-rate smelting time for hot capping is 15~30min; wherein, when the alloy type is a low-expansion high-temperature alloy, the low-melting-rate smelting time is [15~20)min; when the alloy type is other high-temperature alloys, the low-melting-rate smelting time is 20~30min. Specifically, when the alloy type is a low-expansion high-temperature alloy, the low-melting-rate smelting time is 15min, 16min, 17min, 18min, 19min; when the alloy type is other high-temperature alloys, the low-melting-rate smelting time is 20min, 21min, 22min, 23min, 24min, 25min, 26min, 27min, 28min, 29min, 30min.

[0052] When the ingot shape is Φ508mm, the low-melting-rate smelting time for hot capping is 25~40min; wherein, when the alloy type is a low-expansion high-temperature alloy, the low-melting-rate smelting time is [25~30)min; when the alloy type is other high-temperature alloys, the low-melting-rate smelting time is 30~40min. Specifically, when the alloy type is a low-expansion high-temperature alloy, the low-melting-rate smelting time is 25min, 26min, 27min, 28min, 29min; when the alloy type is other high-temperature alloys, the low-melting-rate smelting time is 30min, 31min, 32min, 33min, 34min, 35min, 36min, 37min, 38min, 39min, 40min.

[0053] When the ingot shape is Φ660mm, the low melting rate smelting time for hot capping smelting is 35~65min; wherein, when the alloy type is a low expansion high-temperature alloy, the low melting rate smelting time is [35~45)min; when the alloy type is other high-temperature alloys, the low melting rate smelting time is 45~65min. Specifically, when the alloy type is a low expansion high-temperature alloy, the low melting rate smelting time is 35min, 36min, 37min, 38min, 39min, 40min, 41min, 42min, 43min, 44min; when the alloy type is other high-temperature alloys, the low melting rate smelting time is 45min, 46min, 47min, 48min, 49min, 50min, 51min, 52min, 53min, 54min, 56min, 57min, 59min, 60min, 61min, 61min, 62min, 63min, 64min, 65min.

[0054] The aforementioned limitation on the low-melting-rate smelting time in the later stage of hot capping avoids the problems of long feeding time, long production cycle, and long unstable microstructure region in the low-melting-rate smelting of small ingots and low-expansion high-temperature alloys. It also avoids the problems of short feeding time, poor feeding effect, and large shrinkage cavity size in large ingots and other high-temperature alloys. If the low-melting-rate smelting time in the later stage of hot capping for different ingot types and types of high-temperature alloys exceeds the specified range, it will lead to problems such as long smelting cycle and large alloy feeding kilograms; while if the low-melting-rate smelting time is below the specified range, it is difficult to effectively control the feeding effect and reduce the shrinkage cavity size.

[0055] This application also provides a high-temperature alloy prepared by the above method, with a shrinkage depth of 30~80mm.

[0056] The method for preparing highly dense high-temperature alloys provided by this invention addresses the shrinkage problem in high-temperature alloy products of different ingot shapes and alloy types. Firstly, the larger the ingot size, the higher the steady-state smelting rate and the deeper the molten pool. This results in a longer smelting time for effective molten pool shrinkage during hot capping, leading to a large quantity of alloy used for hot capping and unstable arc shrinkage. This application reduces the smelting rate in the later stages of vacuum consumable steady-state smelting, and the larger the ingot size, the greater the range of smelting rate reduction. This effectively reduces the molten pool volume at the beginning of hot capping, laying the foundation for shortening the hot capping time and reducing the quantity of alloy used for shrinkage during the hot capping stage. Simultaneously, by reducing the smelting rate in the later stages of steady-state smelting in advance, the range of smelting rate reduction during hot capping can be reduced, avoiding arc instability caused by a rapid decrease in smelting rate.

[0057] The influence of high-temperature alloy type on shrinkage cavities is also considered. For example, low-expansion high-temperature alloys generally experience less alloy shrinkage during cooling, resulting in smaller shrinkage cavities, while other high-temperature alloys generally experience greater alloy shrinkage during cooling, leading to larger shrinkage cavities. Based on this, for a given ingot size, a smaller melting rate reduction range is adopted for low-expansion high-temperature alloys to avoid significantly affecting the production cycle; a larger melting rate reduction range is adopted for other alloys to effectively reduce the melting rate during the early stage of hot capping, laying the foundation for effective shrinkage of the molten pool during hot capping and controlling the amount of alloy kilograms used for feeding.

[0058] Furthermore, based on the fact that the larger the size of the high-temperature alloy consumable ingot, the deeper the smelting pool, and the greater the volume shrinkage of the alloy during the hot capping and feeding stage of the consumable ingot, it is proposed that as the size of the consumable ingot increases, the melting rate decreases more significantly in the early stage of hot capping, so as to reduce the volume of the molten pool during the low melting rate smelting in the later stage of hot capping.

[0059] Based on the above, considering that larger alloy consumable ingots have deeper molten pools, greater pool shrinkage, and a greater tendency to form large shrinkage cavities, it is proposed that as the ingot size increases, the low-melting-rate smelting time during hot capping needs to be extended to further promote pool shrinkage in larger consumable ingots and reduce shrinkage cavity size. Simultaneously, considering the influence of alloy type on shrinkage cavities, it is suggested that for the same ingot size, for low-expansion high-temperature alloys, a shorter low-melting-rate smelting time should be used in the later stages of hot capping smelting to avoid increasing the amount of alloy kilograms used for feeding and the length of unstable microstructure regions, while also avoiding increasing the smelting cycle and cost. For other high-temperature alloys, a longer low-melting-rate smelting time should be used in the later stages of hot capping smelting to enhance the alloy feeding effect and significantly reduce shrinkage cavity size.

[0060] The high-density high-temperature alloy and its preparation method provided by this invention clarify the intrinsic relationship between the ingot shape and size of the consumable ingot, alloy type, steady-state smelting process, hot capping smelting process and the shrinkage cavity of the consumable ingot. This enables effective control of the shrinkage cavity of vacuum consumable ingots of different ingot shapes and types, and produces high-density high-temperature alloy products. Furthermore, compared with the prior art that only optimizes the hot blast top process to control the shrinkage cavity size of the consumable ingot, this application effectively reduces the shrinkage cavity size by simultaneously optimizing steady-state smelting and hot capping smelting. While controlling the shrinkage cavity size, it does not increase the amount of alloy kilograms used for feeding, does not increase the length of the unstable microstructure region during the hot capping period, and does not increase the amount of consumable ingot cut.

[0061] In this application, the range values ​​refer to () and [], where () indicates that its left and right endpoint values ​​are not included, and [] indicates that its left and right endpoint values ​​are included; for example, in the above description, (] indicates that its left endpoint value is not included but its right endpoint value is included.

[0062] To further understand the present invention, the preparation method of the high-density high-temperature alloy provided by the present invention will be described in detail below with reference to the embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0063] Example 1

[0064] 1) The chemical composition of the high-temperature alloy 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%, with the balance being Ni and some unavoidable impurity elements. Vacuum self-consumable metallurgical electrode rods are prepared through vacuum induction smelting and processes such as casting-annealing-sawing-peeling-baking-welding.

[0065] 2) The electrode rod prepared in step 1) is placed into a Φ406mm ingot-shaped consumable furnace as a consumable electrode. The furnace door is closed and a vacuum is started. When the vacuum degree and leakage rate meet the requirements, i.e., vacuum degree <0.1Pa and leakage rate <0.1Pa / min, the power can be supplied to start melting.

[0066] The arc initiation stage of the self-consumable smelting process is from 0 to 20 minutes. The arc initiation stage is controlled by current and voltage. The current range of the arc initiation stage is 3.0kA to 7.0kA, and the voltage range is 21V to 25V.

[0067] 3) The steady-state smelting stage of self-consumption smelting is from 21 to 500 minutes. During the steady-state smelting stage, droplet and melting rate control is adopted. The number of droplets is 8 1 / s and the melting rate is 3.2 kg / min. The smelting melting rate is reduced starting 60 minutes before the hot capping smelting period in order to reduce the volume of the molten pool at the hot capping. That is, the melting rate is gradually reduced from 3.2 kg / min in the steady-state smelting stage to 3.0 kg / min in the hot capping stage.

[0068] 4) The period from 501 to 551 minutes is the hot capping smelting stage of self-consumption smelting. The hot capping smelting adopts droplet + melting rate control. The number of droplets is 11~16 1 / s, and the melting rate is 1.2~3.0 kg / min. The period from 501 to 520 minutes is the early stage of hot capping smelting. During this period, the melting rate gradually decreases from 3.0 kg / min to 1.5 kg / min. The period from 521 to 551 minutes is the late stage of hot capping smelting, that is, the low melting rate smelting stage. During this period, the melting rate gradually decreases from 1.5 kg / min to 1.2 kg / min. The smelting time is 30 minutes.

[0069] 5) After the hot capping is completed, the consumable ingot is cooled in the crystallizer for 60 minutes and then removed from the ingot. After air cooling, the consumable ingot is obtained.

[0070] The smelting consumable ingot prepared in this embodiment has a small shrinkage cavity size, with a shrinkage cavity depth of approximately 35 mm.

[0071] Example 2

[0072] The preparation method is basically the same as in Example 1, except that:

[0073] 1) For the smelting of Φ508mm vacuum consumable ingot, the arc-starting stage of the consumable smelting takes place within 0~30min. The arc-starting stage is controlled by current + voltage. The current range of the arc-starting stage is 4.0kA~8.0kA, and the voltage range is 21V~25V.

[0074] 3) The period from 31 to 670 minutes is the steady-state smelting stage of self-consumption smelting. The steady-state droplet count is 8 1 / s and the melting rate is 3.9 kg / min. 120 minutes before the hot capping period, the smelting melting rate is reduced to reduce the volume of the molten pool at the hot capping stage. That is, the melting rate is gradually reduced from 3.9 kg / min in the steady-state smelting stage to 3.4 kg / min in the hot capping stage.

[0075] 4) The period from 671 to 730 minutes is the hot capping smelting stage of self-consumption smelting, with a droplet count of 11 to 16 1 / s and a melting rate of 1.3 to 3.4 kg / min. The period from 671 to 690 minutes is the early stage of hot capping smelting, during which the melting rate gradually decreases from 3.4 kg / min to 1.6 kg / min. The period from 691 to 730 minutes is the late stage of hot capping smelting, i.e., the low melting rate smelting stage, during which the melting rate gradually decreases from 1.6 kg / min to 1.3 kg / min, and the smelting time is 40 minutes.

[0076] 5) After the hot capping is completed, the consumable ingot is cooled in the crystallizer for 90 minutes and then removed from the ingot. After air cooling, the consumable ingot is obtained.

[0077] Testing revealed that the smelting consumable ingot prepared in this embodiment has a small shrinkage cavity size, with a shrinkage cavity depth of approximately 55 mm.

[0078] Example 3

[0079] The preparation method is basically the same as that in Example 1, except that:

[0080] 1) For the smelting of Φ660mm vacuum consumable ingot, the arc-starting stage of the consumable smelting takes place within 0~65min. The arc-starting stage is controlled by current + voltage. The current range of the arc-starting stage is 5.0kA~9.5kA, and the voltage range is 21V~25V.

[0081] 3) The steady-state smelting stage of self-consumption smelting is from 66 to 1000 min. The steady-state droplet count is 8 1 / s and the melting rate is 4.6 kg / min. The smelting rate is reduced starting 300 min before the hot capping stage to reduce the volume of the molten pool at the hot capping stage. That is, the melting rate is gradually reduced from 4.6 kg / min in the steady-state smelting stage to 3.9 kg / min in the hot capping stage.

[0082] 4) The period from 1001 to 1090 min is the hot capping smelting stage of self-consumption smelting, with a droplet count of 11 to 16 1 / s and a melting rate of 1.6 to 3.9 kg / min. The period from 1001 to 1030 min is the early stage of hot capping smelting, during which the melting rate gradually decreases from 3.9 kg / min to 1.9 kg / min. The period from 1031 to 1090 min is the late stage of hot capping smelting, i.e., the low melting rate smelting stage, during which the melting rate gradually decreases from 1.9 kg / min to 1.6 kg / min, and the smelting time is 60 min.

[0083] 5) After the hot capping is completed, the consumable ingot is cooled in the crystallizer for 120 minutes and then removed from the ingot. After air cooling, the consumable ingot is obtained.

[0084] The smelting consumable ingot prepared in this embodiment has a small shrinkage cavity size, with a shrinkage cavity depth of approximately 73 mm.

[0085] Example 4

[0086] The preparation method is basically the same as in Example 2, except that a low-expansion high-temperature alloy is used, and its chemical composition is: C≤0.06, Ni: 35~40%, Cu: 12~16%, Si: 0.25~0.5%, Ti: 1.3~1.8%, Al: C≤0.2, Nb+Ta: 4.3~5.2%, with the balance being Fe and some unavoidable impurity elements;

[0087] The steady-state melting rate of the low-expansion high-temperature alloy is 3.6 kg / min. The melting rate is reduced starting 120 minutes before the hot capping stage, gradually decreasing from 3.6 kg / min in the steady-state melting stage to 3.4 kg / min in the hot capping stage. The low melting rate melting time in the later stage of hot capping is 25 minutes.

[0088] The smelting consumable ingot prepared in this embodiment has a small shrinkage cavity size, with a shrinkage cavity depth of approximately 58 mm.

[0089] Example 5

[0090] The preparation method is basically the same as that in Example 2, except that:

[0091] In the later stage of steady-state smelting, the smelting melting rate is reduced starting 120 minutes before the hot capping smelting, that is, the melting rate is gradually reduced from 3.9 kg / min in the steady-state smelting stage to 3.6 kg / min in the hot capping stage; in the early stage of subsequent hot capping smelting, the smelting melting rate is gradually reduced from 3.6 kg / min to 1.8 kg / min, and in the later stage of hot capping smelting, the smelting melting rate is gradually reduced from 1.8 kg / min to 1.5 kg / min.

[0092] The smelting consumable ingot prepared in this embodiment has a small shrinkage cavity size, with a shrinkage cavity depth of approximately 61 mm.

[0093] Example 6

[0094] The preparation method is basically the same as that in Example 2, except that:

[0095] In the early stage of hot capping smelting, the smelting melting rate decreased from 3.4 kg / min to 1.9 kg / min. In the later stage of hot capping smelting, the smelting melting rate gradually decreased from 1.9 kg / min to 1.6 kg / min.

[0096] The smelting consumable ingot prepared in this embodiment has a small shrinkage cavity size, with a shrinkage cavity depth of approximately 63 mm.

[0097] Example 7

[0098] The preparation method is basically the same as in Example 2, except that:

[0099] In the later stage of hot capping smelting, the smelting melting rate gradually decreased from 1.6 kg / min to 1.3 kg / min, and the low melting rate smelting time was 30 min.

[0100] The smelting consumable ingot prepared in this embodiment has a small shrinkage cavity size, with a shrinkage cavity depth of approximately 60 mm.

[0101] Comparative Example 1

[0102] The preparation method is basically the same as in Example 2, except that:

[0103] The entire steady-state smelting process uses a constant smelting rate of 3.9 kg / min. In the early stage of the self-consumption smelting process, the smelting rate gradually decreases from 3.9 kg / min to 2.1 kg / min. In the later stage of the self-consumption smelting process, the smelting rate gradually decreases from 2.1 kg / min to 1.8 kg / min.

[0104] In this comparative example, the shrinkage and feeding effect of the hot-sealed smelting pool is poor, the size of the self-consuming ingot shrinkage cavity is obvious, and the shrinkage cavity depth reaches about 86mm; at the same time, the amount of alloy used for feeding is about 20kg more, which will increase the cut length of the unstable structure area of ​​the hot-sealed area by about 13mm.

[0105] Comparative Example 2

[0106] The preparation method is basically the same as in Example 2, except that:

[0107] In the later stage of steady-state smelting, the smelting melting rate gradually decreased from 3.9 kg / min in the steady-state smelting stage to 3.7 kg / min in the hot capping stage; in the early stage of subsequent hot capping smelting, the smelting melting rate gradually decreased from 3.7 kg / min to 1.8 kg / min.

[0108] In this comparative example, the melting rate drops rapidly in the early stage of hot capping smelting, which can easily lead to instability of the smelting arc and ultimately affect the quality of the consumable ingot.

[0109] Comparative Example 3

[0110] The preparation method is basically the same as in Example 2, except that:

[0111] In the later stage of steady-state smelting, the smelting melting rate gradually decreased from 3.9 kg / min in the steady-state smelting stage to 3.3 kg / min in the hot capping stage; in the early stage of subsequent hot capping smelting, the smelting melting rate gradually decreased from 3.3 kg / min to 1.5 kg / min.

[0112] In this comparative example, the excessive decrease in melting rate during the later stages of steady-state smelting resulted in a longer smelting cycle and increased production costs.

[0113] Comparative Example 4

[0114] The preparation method is basically the same as in Example 2, except that:

[0115] In the early stage of hot capping smelting, the smelting melting rate decreased from 3.4 kg / min to 1.5 kg / min. In the later stage of hot capping smelting, the smelting melting rate gradually decreased from 1.5 kg / min to 1.2 kg / min.

[0116] In this comparative example, the melting rate dropped rapidly in the early stage of hot capping smelting, and the electric arc was obviously unstable. At the same time, when the melting rate dropped to 1.2 kg / min, the molten pool was significantly not at the edge, and the helium and electric arc were unstable, which ultimately affected the quality of the consumable ingot.

[0117] Comparative Example 5

[0118] The preparation method is basically the same as in Example 2, except that:

[0119] In the later stage of hot capping smelting, the smelting melting rate gradually decreased from 1.6 kg / min to 1.3 kg / min, and the low melting rate smelting time was 20 min.

[0120] In this comparative example, the shrinkage depth of the prepared smelting consumable ingot is approximately 84 mm.

[0121] Comparative Example 6

[0122] The preparation method is basically the same as in Example 2, except that:

[0123] The low-melting-rate smelting time in the later stage of hot capping smelting is 50 minutes.

[0124] In this comparative example, the prepared consumable ingot has a shrinkage depth of about 52 mm. Compared with Example 2, the improvement effect on the shrinkage depth of the consumable ingot is not very significant, but the smelting cycle is increased, which is not conducive to reducing production costs.

[0125] The present invention obtained the shrinkage cavity at the head of the high-temperature alloy consumable ingot prepared in Example 2 and Comparative Example 1 at the production site, such as... Figure 1 As shown, the high-temperature alloy consumable ingot prepared in Example 2 has a small head shrinkage cavity size, with a shrinkage cavity depth of only 55 mm. Figure 1 a), while the high-temperature alloy consumable ingot prepared in Comparative Example 1 showed a large shrinkage cavity at the head, with a shrinkage cavity depth of 86 mm (a). Figure 1 b).

[0126] Meanwhile, this application analyzed the location and depth of the shrinkage cavity center obtained from experimental dissection and simulation prediction of the high-temperature alloy consumable ingot prepared in Example 2, such as... Figure 2As shown, in Example 2, the cavity depth of the consumable ingot obtained from experimental dissection was 55 mm, and the center of the cavity was approximately 40 mm; the simulated predicted cavity depth was 61 mm, and the center of the cavity was approximately 45 mm. The error between the simulated prediction and the experimental results was approximately 10%, indicating that the consumable ingot cavity prediction model established by Meltflow and the analysis results of consumable ingot cavity under different process parameters (i.e., different examples and comparative examples) have a certain degree of reliability.

[0127] 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.

[0128] 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-density high-temperature alloy, comprising the following steps: S1, preparing a high-temperature alloy vacuum consumable electrode rod; S2, vacuum consumable smelting the high-temperature alloy vacuum consumable electrode rod; During the vacuum consumable smelting process, according to the ingot size and alloy type of the high-temperature alloy, the melting rate reduction range in the middle and late stages of stable smelting is determined; According to the ingot size of the high-temperature alloy, the melting rate reduction range in the early stage of hot sealing top smelting is determined; According to the ingot size and alloy type of the high-temperature alloy, the smelting time in the late stage of hot sealing top smelting is determined; When the ingot size of the high-temperature alloy is Φ406mm, the melting rate reduction is greater than 0 and less than or equal to 0.2kg / min 40-80min before the hot sealing top smelting in the middle and late stages of stable smelting; the melting rate reduction is 1.2-1.5kg / min 20-30min before the hot sealing top smelting in the early stage; the low melting rate smelting time in the late stage of hot sealing top smelting is 15-30min; When the high-temperature alloy is a low-expansion high-temperature alloy, the melting rate reduction is greater than 0 and less than or equal to 0.1kg / min 40-80min before the hot sealing top smelting, and the low melting rate smelting time in the late stage of hot sealing top smelting is greater than or equal to 15min and less than 20min; when the high-temperature alloy is other types of high-temperature alloy, the melting rate reduction is 0.1-0.2kg / min 40-80min before the hot sealing top smelting, and the low melting rate smelting time in the late stage of hot sealing top smelting is 20-30min; When the ingot size of the high-temperature alloy is Φ508mm, the melting rate reduction is 0.2-0.5kg / min 90-180min before the hot sealing top smelting in the middle and late stages of stable smelting; the melting rate reduction is 1.5-1.8kg / min 20-30min before the hot sealing top smelting in the early stage; the low melting rate smelting time in the late stage of hot sealing top smelting is 25-40min; When the high-temperature alloy is a low-expansion high-temperature alloy, the melting rate reduction is greater than or equal to 0.2 and less than 0.3kg / min 90-180min before the hot sealing top smelting, and the low melting rate smelting time in the late stage of hot sealing top smelting is greater than or equal to 25min and less than 30min; when the high-temperature alloy is other types of high-temperature alloy, the melting rate reduction is 0.3-0.5kg / min 90-180min before the hot sealing top smelting, and the low melting rate smelting time in the late stage of hot sealing top smelting is 30-40min; When the ingot size of the high-temperature alloy is Φ660mm, the melting rate reduction is 0.4-0.7kg / min 190-300min before the hot sealing top smelting in the middle and late stages of stable smelting; the melting rate reduction is 1.7-2.0kg / min 20-30min before the hot sealing top smelting in the early stage; the low melting rate smelting time in the late stage of hot sealing top smelting is 35-65min; When the high-temperature alloy is a low-expansion high-temperature alloy, the melting rate reduction of the low-expansion high-temperature alloy before the heat capping is greater than or equal to 0.4 kg / min and less than 0.5 kg / min, and the low-melting rate smelting time of the low-expansion high-temperature alloy in the later stage of the heat capping is greater than or equal to 35 min and less than 45 min; when the high-temperature alloy is other types of high-temperature alloy, the melting rate reduction of the low-expansion high-temperature alloy before the heat capping is 0.5-0.7 kg / min, and the low-melting rate smelting time of the low-expansion high-temperature alloy in the later stage of the heat capping is 45-65 min.

2. The production method according to claim 1, characterized by, The low-expansion high-temperature alloy is selected from one or more of GH2907, GH2909 and GH6387.

3. The high-temperature alloy prepared by the preparation method of any one of claims 1-2, wherein the high-temperature alloy has a shrinkage cavity depth of 30-80 mm.

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