A large-aspect-ratio nickel-based heat-resistant alloy electrode ingot and a preparation method thereof

Abstract

This invention relates to a high aspect ratio nickel-based heat-resistant alloy electrode ingot and its preparation method, belonging to the field of electrode ingot preparation technology. The preparation method involves installing an electrode ingot mold on the bottom pad of a vacuum induction furnace casting chamber, with an insulating riser at the top of the mold. A designated area of ​​the mold is preheated using electromagnetic induction heating. During the pouring of molten nickel-based heat-resistant alloy into the mold under vacuum, the superheat of the alloy liquid is increased. After solidification, a nickel-based heat-resistant alloy electrode ingot is obtained. The ratio of the preheating section length to the height of the electrode ingot mold is 0.1-0.5, and the preheating section is located at more than half the height of the electrode ingot mold. The aspect ratio of the electrode ingot mold is 3-12. The resulting high aspect ratio nickel-based heat-resistant alloy electrode ingot exhibits primary shrinkage cavities controlled within the riser section, effectively eliminating secondary shrinkage cavities.

Description

Technical Field

[0001] This invention relates to the field of electrode ingot preparation technology, and in particular to a nickel-based heat-resistant alloy electrode ingot with a high aspect ratio and its preparation method. Background Technology

[0002] High-quality nickel-based heat-resistant, corrosion-resistant, and high-temperature alloys are fundamental guarantees in energy and power engineering. Due to the complex composition and high purity requirements of nickel-based heat-resistant alloys, special smelting processes are commonly used in their production. This involves first melting the raw materials in a vacuum induction furnace, casting them into electrode ingots, and then remelting them in an electroslag remelting furnace or a vacuum arc remelting furnace to improve the purity and density of the alloy ingot. However, the solidification process of nickel-based heat-resistant alloys is prone to segregation and large-sized primary precipitates. The larger the remelted alloy ingot, the more likely it is to develop defects such as black spots and internal cracks. Therefore, the crystallizer size for electroslag remelting or vacuum arc remelting is typically within 1200 mm. To match the crystallizer size during the remelting process and improve the solidification quality of the alloy ingot, the ratio of the diameter of the electrode ingot (filling ratio) to the inner diameter of the crystallizer is usually designed to be between 0.7 and 0.9. Depending on the ingot weight, the height-to-diameter ratio of the electrode ingot is typically above 3:1, and can reach up to 12:1, far exceeding that of general die-cast steel ingots. During solidification, the large height-to-diameter ratio exacerbates defects such as shrinkage cavities and porosity in the electrode ingot. In severe cases, the depth of a primary shrinkage cavity can reach more than 1 / 3 of the ingot's height, and large-sized (millimeters-level) secondary shrinkage cavities penetrate the entire ingot, with the largest shrinkage cavity diameter reaching the centimeter level. This causes instability in the subsequent remelting process, resulting in defects such as black spots, white spots, and inclusion enrichment, which affect the performance of the final product.

[0003] To improve the internal quality of electrode ingots, adding insulating risers or heating the entire ingot mold typically yields limited results, especially for vacuum electrode ingots with large aspect ratios, where the impact on secondary shrinkage cavities is minimal. Alternatively, a water-cooling structure can be installed in the lower half of the ingot mold to enhance bottom cooling; however, the casting chamber is under vacuum during pouring, requiring high equipment sealing, and modifying or adding water-cooling equipment carries risks.

[0004] Therefore, there is an urgent need for a preparation method that can produce high-quality nickel-based heat-resistant alloy vacuum induction electrode ingots with a large aspect ratio. Summary of the Invention

[0005] Based on the above analysis, the present invention aims to provide a high aspect ratio nickel-based heat-resistant alloy electrode ingot and its preparation method, in order to solve the problems of shrinkage cavities and porosity in existing high aspect ratio nickel-based heat-resistant alloy vacuum induction electrode ingots, and improve their internal quality.

[0006] On one hand, the present invention provides a method for preparing a nickel-based heat-resistant alloy electrode ingot with a large aspect ratio, comprising the following steps:

[0007] S1: During the preparation of the vacuum induction furnace casting process, the electrode ingot mold is installed on the bottom pad of the vacuum induction furnace casting chamber, and an insulating riser is provided on the top of the electrode ingot mold.

[0008] S2: Using electromagnetic induction heating, an external electromagnetic coil is used to preheat a designated area of ​​the electrode ingot mold. After preheating, the external electromagnetic coil is removed, and the vacuum induction furnace casting chamber is closed to wait for casting.

[0009] S3: Nickel-based heat-resistant alloy liquid is poured into an electrode ingot mold under vacuum, and the superheat of the alloy liquid is increased during the pouring process. After solidification, nickel-based heat-resistant alloy electrode ingot is obtained.

[0010] The ratio of the length of the preheating section to the height of the electrode ingot mold is 0.1-0.5, the preheating section is located at more than 1 / 2 of the height of the electrode ingot mold, and the height-to-diameter ratio of the electrode ingot mold is 3-12.

[0011] Furthermore, the inner diameter of the electrode ingot mold is

[0012] Furthermore, the inner diameter of the electrode ingot mold is

[0013] Furthermore, the preheating temperature of the electrode ingot mold is 400-1000℃.

[0014] Furthermore, the preheating temperature of the electrode ingot mold is 700-900℃.

[0015] Furthermore, the superheat of the vacuum induction melting casting is 30-150°C.

[0016] Furthermore, the superheat of the vacuum induction melting casting is 30-80°C.

[0017] Furthermore, the ratio of the height of the insulating riser to the height of the electrode ingot mold is 0.02-0.2.

[0018] On the other hand, the present invention provides a nickel-based heat-resistant alloy electrode ingot with a large aspect ratio, which is prepared by the preparation method described in the present invention.

[0019] Furthermore, the primary shrinkage cavity depth of the high aspect ratio nickel-based heat-resistant alloy electrode ingot is less than 100 mm, controlled within the riser section, effectively eliminating secondary shrinkage cavity defects.

[0020] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0021] 1. The electrode ingot preparation method of this invention controls primary shrinkage cavities by placing an insulating riser at the upper end of the electrode ingot mold and locally preheating the electrode ingot mold. By controlling the preheating position, the molten metal at the upper end of the electrode ingot mold is kept at a low cooling intensity during solidification, maintaining the unobstructed feeding channel in the core of the electrode ingot, thus achieving sequential solidification from bottom to top. This preparation method effectively reduces the primary shrinkage cavity depth and secondary shrinkage cavity volume of nickel-based heat-resistant alloy electrode ingots with a height-to-diameter ratio in the range of 3–12. The resulting high-height-ratio nickel-based heat-resistant alloy electrode ingot has its primary shrinkage cavity controlled within the riser section, and the volume of millimeter-level secondary shrinkage cavity defects is controlled below 0.008%.

[0022] 2. In this invention, the electrode ingot mold is preheated and the preheating temperature is controlled at 400-1000℃, so that the nickel-based heat-resistant alloy liquid in the upper part of the electrode ingot mold is still at a relatively slow cooling rate. By utilizing the sequential solidification of the nickel-based heat-resistant alloy liquid, the internal quality of the obtained nickel-based heat-resistant alloy electrode ingot is guaranteed, and the defects of primary shrinkage cavity and secondary shrinkage cavity (millimeter level) are effectively improved.

[0023] 3. In this invention, an electromagnetic induction heating device is installed in the electrode ingot mold. The electrode ingot mold is preheated via electromagnetic heating. The electromagnetic induction heating device does not contact the electrode ingot mold, eliminating the need to modify the original electrode ingot mold. Furthermore, electromagnetic induction heating provides rapid heating, high temperature control precision, and uniform temperature distribution on the inner and outer surfaces of the mold. This invention, with its electromagnetic induction heating device, allows for flexible adjustment of process parameters such as preheating temperature and preheating section position, making it suitable for various nickel-based heat-resistant alloy materials.

[0024] 4. The present invention also proposes to gradually increase the superheat of the alloy liquid during the casting process. On the one hand, this greatly reduces the risk of casting stoppage caused by the low temperature of the alloy liquid and improves the solidification quality of the bottom of the electrode ingot. On the other hand, as the superheat increases, the dendrite bridging phenomenon in the upper part of the electrode ingot can be delayed, the feeding channel can be maintained at all times, and the volume of millimeter-level secondary shrinkage defects inside the electrode ingot can be effectively reduced.

[0025] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0026] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0027] Figure 1This is a schematic diagram of the electrode ingot mold and device used in this invention;

[0028] Figure 2 This is a simulation result diagram of Example 1;

[0029] Figure 3 This is a simulation result of the solid fraction distribution during the solidification process in Example 1;

[0030] Figure 4 This is a simulation result diagram for Example 3;

[0031] Figure 5 The simulation results are shown in Figure 1.

[0032] Figure 6 This is a simulation result of the solid fraction distribution during the solidification process in Comparative Example 1.

[0033] Figure 7 The simulation results are shown in Figure 2 for Comparative Example 2;

[0034] Figure 8 The simulation results are shown in Comparative Example 4.

[0035] Figure 9 This is a simulation result of the solid fraction distribution during the solidification process in Comparative Example 4;

[0036] In the diagram, 1 is the electrode ingot mold; 2 is the heat-insulating riser; 3 is the electromagnetic induction heating device; and 4 is the base pad. Detailed Implementation

[0037] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0038] Nickel-based heat-resistant alloys are widely used in supercritical thermal power plants, high-temperature nuclear reactors, solar thermal power generation, and gas turbines. Generally, nickel-based heat-resistant alloys are prepared through duplex or triple smelting processes. The duplex process refers to melting in a vacuum induction furnace followed by electroslag remelting or vacuum arc remelting, while the triple process refers to melting in a vacuum induction furnace followed by both electroslag remelting and vacuum arc remelting.

[0039] However, the nickel-based heat-resistant alloy electrode ingots obtained after vacuum induction furnace melting have numerous defects such as shrinkage cavities and porosity, directly affecting subsequent smelting or use. Conventional measures such as installing heat-insulating risers on the upper end of the electrode ingot mold cannot effectively reduce defects such as shrinkage cavities and porosity, especially in the preparation of nickel-based heat-resistant alloy electrode ingots with large aspect ratios, where the effect on internal secondary shrinkage cavity defects is even less significant.

[0040] Therefore, the present invention provides a method for preparing a nickel-based heat-resistant alloy electrode ingot with a high aspect ratio, comprising the following steps:

[0041] S1: During the preparation of the vacuum induction furnace casting process, the electrode ingot mold is installed on the bottom pad of the vacuum induction furnace casting chamber, and an insulating riser is provided on the top of the electrode ingot mold.

[0042] S2: Using electromagnetic induction heating, an external electromagnetic coil is used to preheat a designated area of ​​the electrode ingot mold. After preheating, the external electromagnetic coil is removed, and the vacuum induction furnace casting chamber is closed to wait for casting.

[0043] S3: Nickel-based heat-resistant alloy liquid is poured into an electrode ingot mold under vacuum, and the superheat of the alloy liquid is increased during the pouring process. After solidification, nickel-based heat-resistant alloy electrode ingot is obtained.

[0044] The ratio of the length of the preheating section to the height of the electrode ingot mold is 0.1-0.5, the preheating section is located at more than 1 / 2 of the height of the electrode ingot mold, and the height-to-diameter ratio of the electrode ingot mold is 3-12.

[0045] Compared with existing technologies, the electrode ingot preparation method of this invention involves placing an insulating riser at the top of the electrode ingot mold, preheating the mold, controlling the preheating position, and gradually increasing the superheat of the alloy liquid during casting. During solidification, the molten metal at the top of the electrode ingot mold remains at a relatively high temperature, and solidification proceeds sequentially upwards from the bottom of the mold, achieving bottom-up solidification. This preparation method effectively reduces the primary shrinkage depth and secondary shrinkage volume of nickel-based heat-resistant alloy electrode ingots with aspect ratios in the range of 3–12.

[0046] Typically, nickel-based heat-resistant alloys require one or two remeltings after being cast into induction electrode ingots to improve the purity and density of the alloy ingot. However, due to the high degree of alloying in nickel-based heat-resistant alloys, segregation and large-sized primary precipitates are prone to occur during solidification. The larger the remelted alloy ingot, the more likely it is to develop defects such as black spots and internal cracks, which can lead to the scrapping of the entire ingot in severe cases. Therefore, the crystallizer size for electroslag remelting or vacuum arc remelting of nickel-based heat-resistant alloys is usually within 1200 mm. To match the crystallizer size during the remelting process and improve the solidification quality of the alloy ingot, the ratio of the diameter of the vacuum induction electrode ingot to the inner diameter of the crystallizer (filling ratio) is usually designed to be between 0.7 and 0.9. Depending on the ingot weight, the height-to-diameter ratio of the electrode ingot can reach up to 12:1, which is much larger than that of general die-cast steel ingots.

[0047] For example, the height-to-diameter ratio of the electrode ingot mold can be 3, 4.9, 6.3, 9.5, or 12. Furthermore, the height-to-diameter ratio gradually decreases as the inner diameter increases.

[0048] The electromagnetic induction preheating method employed in this invention differs from traditional whole-piece preheating or riser preheating techniques. Based on the problem of secondary shrinkage cavities caused by rapid local cooling and premature dendrite bridging in the core of the electrode ingot during solidification with a large aspect ratio, this invention preheats specific areas of the mold to delay dendrite bridging, achieving "sequential solidification." However, on the one hand, the dendrite bridging area is significantly affected by process factors; a preheating section that is too small may not be able to heat the original bridging location. On the other hand, a preheating section that is too long will reduce the overall cooling rate, weakening the effect of delaying local dendrite bridging and increasing the difficulty of equipment processing. Therefore, a length of 0.1-0.5 is adopted. In this invention, the preheating section is located above 1 / 2 of the electrode ingot mold height, with its center at 3 / 4 of the mold height, to delay the effect of local dendrite bridging.

[0049] For example, the ratio of the length of the preheating section to the height of the electrode ingot mold can be 0.1, 0.2, 0.3, 0.4 or 0.5.

[0050] Preferably, the ratio of the preheating section length to the electrode ingot mold height is 0.2-0.4.

[0051] Specifically, the inner diameter of the electrode ingot mold

[0052] Preferably, the inner diameter of the electrode ingot mold is

[0053] Specifically, the preheating temperature of the electrode ingot mold is 400-1000℃.

[0054] This invention preheats the electrode ingot mold using electromagnetic heating. By controlling the temperature and height of the preheating section, sequential solidification can be achieved, effectively reducing the depth of primary shrinkage cavities and the volume of secondary shrinkage cavities in the nickel-based heat-resistant alloy electrode ingot. When the preheating temperature is below 400°C, the defect improvement effect in the nickel-based heat-resistant alloy electrode ingot is not significant. However, when the preheating temperature is too high, the strength of the electrode ingot mold decreases, posing a significant safety risk.

[0055] For example, the preheating temperature of the electrode ingot mold can be 400℃, 430℃, 450℃, 480℃, 500℃, 520℃, 550℃, 580℃, 600℃, 630℃, 650℃, 680℃, 700℃, 720℃, 750℃, 780℃, 800℃, 850℃, 900℃, 930℃, 950℃, 980℃, or 1000℃.

[0056] Preferably, the preheating temperature of the electrode ingot mold is 700-900℃.

[0057] Specifically, the superheat of the vacuum induction melting casting is 30-150℃.

[0058] The superheat control method employed in this invention differs from conventional low-superheat casting processes. During casting, the superheat of the alloy melt is gradually increased by altering the output power of the vacuum induction furnace, further delaying dendrite bridging in the upper part of the electrode ingot. When the superheat of vacuum induction melting casting is too low, it may lead to solidification and casting stoppage; when the superheat of vacuum induction melting casting is too high, it exacerbates the reaction between the nickel-based heat-resistant alloy melt and the crucible refractory material in the vacuum induction furnace during the melting process, affecting the purity of the nickel-based heat-resistant alloy melt; furthermore, it affects the solidification structure, increasing the probability of shrinkage cavities and porosity defects.

[0059] For example, the superheat of the vacuum induction melting casting can be 30°C, 50°C, 80°C, 100°C, 130°C or 150°C.

[0060] The present invention preferably uses a vacuum induction melting casting superheat of 30-80°C, which improves the internal solidification quality while avoiding the formation of secondary shrinkage cavities.

[0061] The process of increasing the superheat during casting can be continuous, for example, the superheat can be gradually increased from 30°C to 150°C, or from 30°C to 80°C, or from 80°C to 150°C.

[0062] The process of increasing the superheat during casting can also be discontinuous. For example, during the initial casting, the alloy superheat is maintained at 50°C and casting continues. When the alloy liquid in the crucible of the melting furnace is poured to 1 / 2 full, the holding power of the vacuum induction furnace is increased to rapidly raise the superheat from the initial casting temperature of 50°C to 80°C until casting is complete. Similarly, when the alloy liquid in the crucible is poured to 2 / 3 full, the holding power of the vacuum induction furnace is increased to raise the superheat from 60°C to 100°C.

[0063] Specifically, the ratio of the height of the insulating riser to the height of the electrode ingot mold is 0.02-0.2.

[0064] The riser is located at the last solidification point during the solidification process, and it can compensate for the shrinkage of the nickel-based heat-resistant alloy liquid in the electrode ingot mold. When the ratio of the height of the insulating riser to the height of the electrode ingot mold is less than 0.02, the height of the insulating riser is too short, making it difficult to control the final liquid level within the riser area during the pouring process, thus failing to achieve the purpose of shrinkage compensation. When the ratio of the height of the insulating riser to the height of the electrode ingot mold is greater than 0.2, the weight of the riser location accounts for a large proportion of the entire nickel-based heat-resistant alloy electrode ingot, which is not conducive to subsequent cutting and reduces the yield of the product.

[0065] A high aspect ratio nickel-based heat-resistant alloy electrode ingot was obtained by the preparation method of the present invention. The aspect ratio of the electrode ingot mold is 3-12, and the inner diameter of the electrode ingot mold is φ80-920mm. After performance testing, the primary shrinkage depth of the obtained high aspect ratio nickel-based heat-resistant alloy electrode ingot is less than 100mm, and the secondary shrinkage volume is less than 0.008%.

[0066] To more clearly describe the present invention, Example 1 is further illustrated by the following embodiments and comparative examples.

[0067] A method for preparing a nickel-based heat-resistant alloy electrode ingot with a high aspect ratio includes the following steps:

[0068] Reference Figure 1 S1: The electrode ingot mold 1 is installed on the bottom pad 4 of the casting chamber of the vacuum induction furnace, and an insulating riser 2 is provided on the top of the electrode ingot mold 1.

[0069] The inner diameter of the electrode ingot mold 1 is... The height of electrode ingot mold 1 is 2580mm, and the height-to-diameter ratio is 6:1; the ratio of the height of the heat-insulating riser 2 to the height of electrode ingot mold 1 is 0.1.

[0070] S2: The electrode ingot mold 1 is preheated using an electromagnetic induction heating device 3, which is an external electromagnetic coil; the ratio of the length of the preheating section to the height of the electrode ingot mold 1 is 0.3, the length of the preheating section is 774mm, the center of the preheating section is located at 3 / 4 of the electrode ingot mold (from bottom to top), and the preheating temperature is 700℃.

[0071] S3: Finally, the nickel-based heat-resistant alloy liquid is poured into the electrode ingot mold 1 under vacuum. After solidification, the nickel-based heat-resistant alloy electrode ingot is obtained.

[0072] The superheat of the nickel-based heat-resistant alloy liquid in the initial casting stage is 35°C. During the casting process, the output power of the vacuum induction furnace is increased to gradually increase the superheat, reaching 65°C at the end of the casting. The grade of the nickel-based heat-resistant alloy is C-HRA-3.

[0073] Example 2

[0074] The preparation process of Example 2 is largely the same as that of Example 1, except that in step S1 of Example 2, the inner diameter of the electrode ingot mold is... The height-to-diameter ratio is 4.9:1; the ratio of the height of the insulating riser to the height of the electrode ingot mold is 0.14.

[0075] In step S2, the preheating temperature is 800℃, and the ratio of the length of the preheating section to the height of the electrode ingot mold is 0.5.

[0076] In step S3, the superheat of the nickel-based heat-resistant alloy liquid during the initial casting stage is 35°C. During the casting process, the output power of the vacuum induction furnace is increased to gradually increase the superheat, reaching 50°C at the end of the casting. The grade of the nickel-based heat-resistant alloy is Inconel X750.

[0077] Example 3

[0078] The preparation process of Example 3 is largely the same as that of Example 2, except that the nickel-based heat-resistant alloy in step S3 of Example 3 is grade C650R.

[0079] Example 4

[0080] The preparation process of Example 4 is largely the same as that of Example 1, except that in step S1 of Example 4, the inner diameter of the electrode ingot mold is... The height-to-diameter ratio is 9.5:1.

[0081] Example 5

[0082] The preparation process of Example 5 is largely the same as that of Example 1, except that in step S2 of Example 5, the ratio of the length of the preheating section to the height of the electrode ingot mold is 0.1.

[0083] Example 6

[0084] The preparation process of Example 6 is largely the same as that of Example 1, except that the preheating temperature in step S2 of Example 6 is 900°C.

[0085] Example 7

[0086] The preparation process of Example 7 is largely the same as that of Example 1, except that the preheating temperature in step S2 of Example 7 is 400°C.

[0087] Example 8

[0088] The preparation process of Example 8 is largely the same as that of Example 1, except that in step S3 of Example 8, the superheat of the nickel-based heat-resistant alloy liquid is 120°C.

[0089] Example 9

[0090] The preparation process of Example 9 is largely the same as that of Example 1. The difference is that in step S3 of Example 9, the superheat of the alloy liquid is 35°C at the beginning of casting. After half of the alloy liquid is poured into the crucible, the output power of the vacuum induction furnace is increased to gradually increase the superheat to 70°C until the casting is completed.

[0091] Comparative Example 1

[0092] The preparation process of Comparative Example 1 is largely the same as that of Example 1, except that Comparative Example 1 does not have an insulating riser installed and is not preheated.

[0093] Comparative Example 2

[0094] The preparation process of Comparative Example 2 is largely the same as that of Example 1, except that Comparative Example 2 is equipped with an insulating riser and is not preheated.

[0095] Comparative Example 3

[0096] The preparation process of Comparative Example 3 is largely the same as that of Example 1, except that the ratio of the length of the preheating section to the height of the electrode ingot mold in Comparative Example 3 is 0.7.

[0097] Comparative Example 4

[0098] The preparation process of Comparative Example 4 is largely the same as that of Example 1. The difference is that the superheat of the alloy liquid at the beginning of casting in Comparative Example 4 is 65°C. During the casting process, the superheat of the alloy liquid is gradually reduced by controlling the output power of the vacuum induction furnace, and reaches 35°C at the end of casting.

[0099] Comparative Example 5

[0100] The preparation process of Comparative Example 5 is largely the same as that of Example 1, except that the electrode ingot mold in Comparative Example 5 is heated as a whole.

[0101] Performance testing

[0102] Nickel-based heat-resistant alloy electrode ingots were prepared according to the preparation methods of Examples 1-9 and Comparative Examples 1-5. The depth of the primary shrinkage cavity and the volume of the secondary shrinkage cavity (in millimeters) of the nickel-based heat-resistant alloy electrode ingots were measured. The specific test results are shown in Table 1, and the simulation results are shown in the figure below. Figure 2-9 As shown.

[0103] Table 1 Test Results

[0104]

[0105]

[0106] Referring to Examples 1-9 and Comparative Examples 1-5, and in conjunction with Table 1, Figure 2-9 As can be seen, by using the preparation method provided by the present invention, preheating the electrode ingot mold, controlling the preheating position, and increasing the superheat of the alloy liquid, the resulting nickel-based heat-resistant alloy electrode ingot with a height-to-diameter ratio of 3 to 12 has a primary shrinkage depth of less than 100 mm and a secondary shrinkage volume of less than 0.008%.

[0107] Referring to Examples 1-9 and Comparative Examples 1-5 and in conjunction with Table 1, Figure 2 , Figure 5and Figure 7 When using the preparation method of Example 1, the upper part of the ingot mold is preheated and the superheat is gradually increased from 30°C to 50°C. The dendrite bridging in the upper part of the electrode ingot is significantly delayed, the solidification quality at the bottom is significantly improved, and the volume of the secondary shrinkage cavity is significantly reduced.

[0108] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method of producing a large aspect ratio nickel-base heat resistant alloy electrode ingot, characterized by, Includes the following steps: S1: During the preparation process of vacuum induction furnace casting, the electrode ingot mold is installed on the bottom pad of the vacuum induction furnace casting chamber. An insulating riser is provided on the top of the electrode ingot mold, and the insulating riser is located inside the electrode ingot mold; the ratio of the height of the insulating riser to the height of the electrode ingot mold is 0.02-0.

2. S2: Using electromagnetic induction heating, an external electromagnetic coil is used to preheat a designated area of ​​the electrode ingot mold at a temperature of 680-1000℃. After preheating, the external electromagnetic coil is removed and the vacuum induction furnace casting chamber is closed to wait for casting. S3: In a vacuum environment, nickel-based heat-resistant alloy liquid is poured into an electrode ingot mold, and the superheat of the alloy liquid is increased during the pouring process. The superheat is 30-150℃. After solidification, nickel-based heat-resistant alloy electrode ingot is obtained. The primary shrinkage cavity depth of the nickel-based heat-resistant alloy electrode ingot is less than 100mm, and the secondary shrinkage cavity volume is less than 0.008%. The ratio of the length of the preheating section to the height of the electrode ingot mold is 0.1-0.5, the preheating section is located at more than 1 / 2 of the height of the electrode ingot mold, and the height-to-diameter ratio of the electrode ingot mold is 3-12.

2. The method of claim 1, wherein the high aspect ratio nickel-based heat- resistant alloy electrode ingot is prepared by the steps of: The inner diameter of the electrode ingot mold is φ80~920mm.

3. The method of claim 2, wherein the electrode ingot is prepared by the steps of: The inner diameter of the electrode ingot mold is φ430-920mm.

4. The method of claim 1, wherein the electrode ingot has a high aspect ratio. The preheating temperature of the electrode ingot mold is 700-1000℃.

5. The method for preparing the high aspect ratio nickel-based heat-resistant alloy electrode ingot according to claim 4, characterized in that, The preheating temperature of the electrode ingot mold is 700-900℃.

6. The method of claim 1, wherein the electrode ingot has a high aspect ratio. The superheat is 30-130℃.

7. The method of claim 6, wherein the electrode ingot is prepared by the steps of: The superheat is 30-80℃.

8. The method for preparing the high aspect ratio nickel-based heat-resistant alloy electrode ingot according to claim 1, characterized in that, The ratio of the height of the insulating riser to the height of the electrode ingot mold is 0.02-0.

14.

9. A nickel-based heat-resistant alloy electrode ingot with a high aspect ratio, characterized in that, It is prepared by the preparation method according to any one of claims 1-8.

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