A consumable melting method for preparing an axially compositionally graded HT700P-HT700T ingot

Abstract

This invention belongs to the field of high-temperature alloy smelting technology and discloses a self-consumable melting method for preparing HT700P-HT700T ingots with axial compositional gradient. The method includes: reverse-engineering the axial dimensions and tenon-and-mortise interface geometry parameters of the transition section of a combined self-consumable electrode based on the target axial compositional gradient distribution of the ingot; preparing a first alloy electrode and a second alloy electrode with the aforementioned interface and connecting them to form a combined self-consumable electrode; remelting the electrode in a vacuum self-consumable arc furnace; adaptively adjusting the power supply regime and controlling the melting rate based on the mapping relationship between the electrode consumption position and the process parameter set when melting to the transition section; and obtaining an HT700P-HT700T alloy ingot with axial compositional gradient after furnace cooling. This invention achieves precise control over the compositional gradient distribution morphology and transition zone length of the ingot, resulting in a stable melting process, smooth compositional transition, and good metallurgical quality.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature alloy smelting technology, specifically relating to a self-consumable melting method for preparing axial composition gradient HT700P-HT700T ingots. Background Technology

[0002] As energy and power equipment develops towards extreme performance, the loads and environments experienced by its core hot-end components (such as rotors and pipes) vary significantly in different locations, thus posing differentiated requirements for material properties. Using a single homogeneous material is insufficient to simultaneously meet the performance requirements across the entire service range, while components composed of heterogeneous materials pose risks to interface reliability. Therefore, integrated materials with gradient variations in composition and properties have emerged as a new solution.

[0003] HT700P and HT700T are new iron-nickel-based high-temperature alloys independently developed for 650~700℃ ultra-supercritical generator sets. They are suitable for components such as pipes and valve bodies, as well as high-temperature heating surfaces such as superheaters and reheaters. They have advantages such as good high-temperature strength, corrosion and oxidation resistance, structural stability and controllable cost, making them ideal materials for manufacturing key components of generator sets.

[0004] In consumable metallurgy processes such as vacuum arc remelting (VAR), controlling the solidification process to regulate the composition of the ingot is a potential technological approach for preparing gradient materials. Currently, the relevant technologies mainly include the following three: (1) Timed addition of alloying elements method: Different alloying elements are added to the molten pool in sequence during the smelting process in order to achieve compositional changes. However, this method has low precision in controlling the composition and it is difficult to achieve a precise and continuous compositional gradient.

[0005] (2) Changing smelting electrical parameters: This involves influencing the molten pool morphology and solidification behavior by adjusting parameters such as smelting current. However, the adjustable range of a single parameter is limited, and large adjustments to the current can easily affect arc stability, making it difficult to balance composition control and metallurgical quality control.

[0006] (3) Heterogeneous electrode assembly welding method: Electrodes with different compositions are welded together and then melted to obtain an ingot with a gradient composition. Although this method can achieve macroscopic changes in composition, it lacks precise control over the solidification process. On the one hand, the solidification conditions change abruptly at the electrode transition, which can easily lead to metallurgical defects. On the other hand, the composition distribution range is limited and difficult to control precisely, making it impossible to form a stable and controllable composition gradient.

[0007] In summary, existing technologies for preparing gradient materials using consumable metallurgy generally suffer from problems such as low precision in composition control, limited control range, and poor interfacial metallurgical quality, making it difficult to achieve a smooth and controllable transition from one alloy composition to another. Therefore, there is an urgent need to develop a consumable metallurgy method capable of precisely controlling the composition gradient to meet the potential manufacturing requirements of integrated gradient materials for hot-end components. Summary of the Invention

[0008] The purpose of this invention is to provide a self-consumable melting method for preparing axial composition gradient HT700P-HT700T ingots, which solves the problems of low composition control accuracy, limited control range, and poor interfacial metallurgical quality that are commonly found in the prior art when preparing gradient materials using self-consumable melting.

[0009] This invention is achieved through the following technical solution: This invention discloses a self-consumable melting method for preparing axial composition gradient HT700P-HT700T ingots, comprising the following steps: S1. Based on the target composition gradient distribution along the ingot axis, and combined with the mathematical model relating the vacuum consumable arc melting process parameters to the depth of the molten pool, the interface of the combined consumable electrode is designed in reverse. The combined consumable electrode has a transition section. The axial dimensions and interface geometric parameters of the transition section are designed. The combined consumable electrode includes a first alloy electrode and a second alloy electrode. S2. According to the design results of S1, prepare a first alloy electrode and a second alloy electrode with the interface respectively, and connect the first alloy electrode and the second alloy electrode through the interface to obtain a combined consumable electrode. S3. The combined consumable electrode is placed in a vacuum consumable arc furnace for remelting. During the remelting process, the first alloy electrode is connected to the auxiliary electrode, and remelting begins from the end of the second alloy electrode. According to the preset mapping relationship between the electrode consumption position and the process parameter group, the power supply system is adaptively adjusted when melting reaches the transfer section to control the electrode melting rate. S4. After remelting, the furnace is cooled to obtain HT700P-HT700T ingots with axial composition gradient.

[0010] Furthermore, in step S1, the interface is a mortise and tenon structure, including a male end provided at the end of the first alloy electrode and a female end provided at the end of the second alloy electrode.

[0011] Furthermore, the male end is a truncated conical or cylindrical shape.

[0012] Furthermore, when the male end is a truncated conical shape, its minimum diameter D i With the maximum diameter D f The ratio ranges from 0.3 to 1, and the maximum diameter Df Not greater than the electrode diameter De.

[0013] Furthermore, in step S1, the axial dimension Z of the transition section is Z = L_target(z) - H S ; Where L_target(z) is the target length of the axial composition gradient segment of the ingot, and H S The steady-state molten pool depth is defined as that used in vacuum consumable arc melting with combined electrodes.

[0014] Furthermore, in step S3, the electrode melting rate is controlled according to the following formula: V e =6.273-15.13·0.996 De In the formula, V e D is the electrode melting rate. e The diameter is the electrode diameter.

[0015] Furthermore, the electrode diameter ranges from 260 to 840 mm.

[0016] Furthermore, in step S2, the first alloy electrode and the second alloy electrode have the same nominal outer diameter, and their actual outer diameter deviation is ≤30 mm.

[0017] Furthermore, the first alloy electrode is HT700P, and the second alloy electrode is HT700T.

[0018] The present invention also discloses an axial composition gradient HT700P-HT700T ingot, which is prepared by the method described above.

[0019] Compared with the prior art, the present invention has the following beneficial technical effects: This invention provides a consumable melting method for preparing axial composition gradient HT700P-HT700T ingots. Through the coordinated control of electrode geometry and melting rate, programmable control of the molten pool morphology is achieved. Compared to single-parameter adjustment methods, this invention expands the process control range, avoids drastic changes in molten pool morphology caused by large parameter fluctuations, and makes the composition transition more stable and controllable.

[0020] This invention employs a combined electrode preparation method combining segmented casting and mortise and tenon joint connection. The electrode blank can be formed using existing vacuum induction melting equipment, and reliable connection can be achieved through machining and welding. It has strong process compatibility, is easy to operate, and has good prospects for industrial application.

[0021] This invention, through reverse design of the axial dimensions and interface geometry of the transition section, combined with programmed melting rate control, can precisely control the distribution pattern and transition zone length of the axial composition gradient of the ingot according to the target composition distribution function, realizing multi-type gradient design from linear gradient to complex curve gradient, significantly improving the flexibility and controllability of composition gradient design. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a combined electrode structure; Figure 2 The component gradient requirement function curves for each embodiment; Figure 3 Figure 1 shows a schematic diagram of the combined electrode connector structure in each embodiment; Figure 2 shows a schematic diagram of the combined electrode connector structure in embodiment 1; Figure 3 shows a schematic diagram of the combined electrode connector structure in embodiment 2; Figure 4 shows a schematic diagram of the combined electrode connector structure in comparative example 1. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention; that is, the described embodiments are only a part of the embodiments of the present invention, and not all of them.

[0024] The detailed description of the embodiments of the present invention provided in the following figures is not intended to limit the scope of the claimed invention, but merely to illustrate one selected embodiment of the invention. All other embodiments obtained by those skilled in the art based on the figures and embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0025] This invention proposes designing and fabricating two alloy electrodes with specific geometric interfaces for combination. By controlling the physical characteristics of the electrodes at the interface and combining this with directional control of the melting rate, the heat input during melting can be regulated, thereby influencing the molten pool and achieving stable control of the composition gradient. Specifically, a transition section between the two alloy electrodes is designed on the electrodes to achieve a stable transition during the melting process, improving the controllability of the length of the composition gradient distribution. Furthermore, the electrode melting rate is a key control parameter. A lower melting rate typically results in a shallower molten pool and a higher solidification rate for the ingot; an increased melting rate, on the other hand, results in a deeper molten pool and slower solidification.

[0026] By systematically coordinating changes in electrode geometry with real-time adjustments to the melting rate, the changes in electrode structure can be used as a setting basis, while melting rate adjustment serves as a means of fine compensation and stable control, jointly achieving stable and precise programmable control of the molten pool morphology. This systematic method proactively designs and controls the composition distribution through the synergy of "structured electrodes" and "programmed melting rates," thereby achieving an axial composition gradient distribution in the ingot.

[0027] This invention provides a self-consumable melting method for preparing HT700P-HT700T ingots with axial compositional gradients. Through the synergistic control of "structured electrodes" and "programmed melting rate," precise regulation of the ingot's compositional gradient is achieved. Specifically, it includes the following steps: S1. Composition Target Mapping and Combined Electrode Structure Design Based on the target element distribution function C_target(z) of the axial composition gradient segment of the ingot, and combined with the mathematical model relating the vacuum consumable arc melting process parameters to the depth of the molten pool, the axial dimension Z of the consumable electrode transition segment and the mortise and tenon interface diameter of the HT700P and HT700T alloys are designed in reverse.

[0028] Wherein, the axial dimension of the transition section Z = L_target(z) - H S In the formula, L_target(z) is the target length of the axial composition gradient segment of the ingot, and H S The steady-state molten pool depth is defined as that used in vacuum consumable arc melting with combined electrodes.

[0029] The mathematical model relating the vacuum self-consuming arc melting process parameters to the molten pool depth is a quantitative relationship established in the early stages through finite element numerical simulation and experiments, between process parameters such as electrode melting rate and cooling conditions and the molten pool depth. This model is used to predict the steady-state molten pool depth H under specific melting conditions. S .

[0030] like Figure 1 As shown, the end shapes of two electrode blanks are designed, one as the male electrode and the other as the female electrode, forming a tenon-and-mortise joint transition section.

[0031] The male connector of the consumable electrode interface is a truncated conical (or cylindrical) shape, with its top being the smallest end and its smallest diameter D. i With the maximum diameter D f The ratio ranges from 0.3 to 1, and the maximum diameter D f Not greater than the electrode diameter D e D i and D f The specific value is determined by the requirements of the target element distribution function C_target(z) of the axial composition gradient segment of the ingot. Correspondingly, a conical groove is hollowed out at the end of the female electrode.

[0032] S2, Fabrication of Combined Electrodes According to the design results of S1, HT700P and HT700T electrode blanks with truncated conical tenon-and-mortise joints are cast separately in a specially designed irregularly shaped ingot mold through vacuum induction melting. That is, the ends of the two electrode blanks are respectively designed with "male" or "female" shapes. HT700P serves as the male electrode, i.e., the first alloy electrode, and HT700T serves as the female electrode, i.e., the second alloy electrode, forming a tenon-and-mortise joint transition section.

[0033] Then, the male electrode is inserted into the female electrode, and the electrodes of the two alloys are connected through the interface by machining and welding to obtain a combined consumable electrode of HT700P / HT700T alloys; the consumable electrodes of the two alloys have the same nominal outer diameter, and their actual outer diameter deviation is ≤30 mm.

[0034] In this step, welding is performed at the joints to make them a strong whole, with a mortise and tenon joint in the middle for transition.

[0035] S3, Diameter-Melt Rate Co-programmed Remelting The combined electrode prepared by S2 is placed in a vacuum arc furnace and a preset self-consuming remelting program is executed. During remelting, the tail of the male electrode in the combined electrode is connected to the auxiliary electrode, and remelting is preferentially started from the female electrode.

[0036] The program defines a mapping relationship between the axial position of the electrode and the set of melting process parameters based on the weight consumed by the combined electrode. When melting reaches the transition section, the control system adaptively adjusts the power supply to achieve the expected electrode melting rate V at this stage. e This allows for stable control of the solidification behavior of the ingot during this stage, thereby accurately controlling the gradient distribution of the composition.

[0037] The electrode melting rate V e =6.273-15.13·0.996 De In the formula D e V represents the electrode diameter in mm, ranging from 260 to 840 mm. e The unit is kg / min.

[0038] Specifically, when melting reaches the transition section of the mortise and tenon structure, the system adjusts the power supply parameters according to the preset program, which works in conjunction with the gradually thickening geometry of the male end to allow the two alloy components to slowly mix in the molten pool in a designed ratio, and finally solidify into an HT700P-HT700T alloy ingot with continuously changing composition.

[0039] S4. Ingot post-processing After vacuum arc remelting is completed, an ingot with an axial compositional gradient is obtained.

[0040] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0041] Example 1 This embodiment provides a self-consumable melting method for preparing axial composition gradient HT700P-HT700T ingots, including the following steps: S1, The design adopts electrode diameter D e Given a diameter of 330mm, determine the target element distribution function C_target(z) for the axial composition gradient segment of the ingot. The axial (Z) composition distribution conforms to... Figure 2 In Example 1, the transition section, except for the beginning and end, exhibits an approximately linear compositional change in most areas. The target length of the axial compositional gradient section of the ingot is L_target(z) = 400 mm. The interface dimension Z = L_target(z) - H is then determined. S D i = D f =0.5D e That is, the connector can be simplified to, for example... Figure 3 The cylindrical shape shown in Figure a; S2. Preparation of combined electrodes: According to the design results of S1, HT700P and HT700T electrode blanks with stepped cylindrical tenon and mortise interfaces are cast separately in a specially designed structural ingot mold by vacuum induction melting. Through machining and welding, the electrodes of the two alloys are connected through the interface to obtain a combined consumable electrode of HT700P / HT700T alloys. The consumable electrodes of the two alloys have the same nominal outer diameter, and the actual deviation of their outer diameter is ±20 mm. S3. Diameter-Melting Rate Coordinated Programmed Remelting: The combined electrode prepared in S2 is placed in a vacuum arc furnace, and a preset consumable remelting program is executed. During remelting, the tail of the male electrode (HT700P alloy) in the combined electrode is connected to the auxiliary electrode, and remelting preferentially starts from the female electrode (HT700T alloy). When the melting reaches the transition section, the control system adjusts to achieve the expected electrode melting rate V. e =6.273-15.13·0.996 De In the formula D e V represents the electrode diameter in mm. e The unit is kg / min. The target value for the electrode melting rate is 2.08 kg / min.

[0042] S4. Ingot post-processing: After vacuum consumable melting, HT700P-HT700T ingots with axial composition gradients are obtained.

[0043] The ingots prepared in this embodiment were tested, and the data are shown in Table 1.

[0044] Table 1 Data from Example 1

[0045] Example 2 This embodiment provides a self-consumable melting method for preparing axial composition gradient HT700P-HT700T ingots, including the following steps: S1, The design adopts electrode diameter D e Given a diameter of 330mm, determine the target element distribution function C_target(z) for the axial composition gradient segment of the ingot. The axial (Z) composition distribution conforms to... Figure 2 The curve shown in Example 2 indicates that the composition of the transition section varies multiple times, and the target length of the axial composition gradient segment of the ingot is L_target(z) = 400 mm. The interface dimension Z = L_target(z) - H is determined. S D i =0.6D f D f =D e That is, the connector can be simplified to, for example... Figure 3 The cone shape shown in Figure b; S2. Preparation of combined electrodes: According to the design results of S1, HT700P and HT700T electrode blanks with truncated conical tenon-and-mortise interfaces were cast separately in a specially designed structural ingot mold by vacuum induction melting. Through machining and welding, the electrodes of the two alloys were connected through the interface to obtain a combined consumable electrode of HT700P / HT700T alloys. The consumable electrodes of the two alloys have the same nominal outer diameter, and the actual deviation of their outer diameter is ±20 mm. S3. Diameter-Melting Rate Coordinated Programmed Remelting: The combined electrode prepared in S2 is placed in a vacuum arc furnace, and a preset consumable remelting program is executed. During remelting, the tail of the male electrode (HT700P alloy) in the combined electrode is connected to the auxiliary electrode, and remelting preferentially starts from the female electrode (HT700T alloy). When the melting reaches the transition section, the control system adjusts to achieve the expected electrode melting rate V. e =6.273-15.13·0.996 De In the formula D e V represents the electrode diameter in mm. e The unit is kg / min. The target value for the electrode melting rate is 2.08 kg / min; S4. Ingot post-processing: After vacuum consumable melting, HT700P-HT700T ingots with axial composition gradients are obtained.

[0046] The ingots prepared in this embodiment were tested, and the data are shown in Table 2.

[0047] Table 2 Data from Example 2

[0048] Example 3 This embodiment provides a self-consumable melting method for preparing axial composition gradient HT700P-HT700T ingots, including the following steps: S1, The design adopts electrode diameter D e Given a diameter of 330mm, determine the target element distribution function C_target(z) for the axial composition gradient segment of the ingot. The axial (Z) composition distribution conforms to... Figure 2 The curve shown in Example 3 indicates that the composition of the transition section varies multiple times, and the target length of the axial composition gradient section of the ingot is L_target(z) = 500 mm. The interface dimension Z = L_target(z) - H is then determined. S D i =0.3D f D f =D e That is, the connector can be simplified to, for example... Figure 3 The cone shape shown in Figure c; S2. Preparation of combined electrodes: According to the design results of S1, HT700P and HT700T electrode blanks with truncated conical tenon-and-mortise interfaces were cast separately in a specially designed structural ingot mold by vacuum induction melting. Through machining and welding, the electrodes of the two alloys were connected through the interface to obtain a combined consumable electrode of HT700P / HT700T alloys. The consumable electrodes of the two alloys have the same nominal outer diameter, and the actual deviation of their outer diameter is ±20 mm. S3. Diameter-Melting Rate Coordinated Programmed Remelting: The combined electrode prepared in S2 is placed in a vacuum arc furnace, and a preset consumable remelting program is executed. During remelting, the tail of the male electrode (HT700P alloy) in the combined electrode is connected to the auxiliary electrode, and remelting preferentially starts from the female electrode (HT700T alloy). When the melting reaches the transition section, the control system adjusts to achieve the expected electrode melting rate V. e =6.273-15.13·0.996 De In the formula D e V represents the electrode diameter in mm. e The unit is kg / min. The target value for the electrode melting rate is 2.08 kg / min; S4. Ingot post-processing: After vacuum consumable melting, HT700P-HT700T ingots with axial composition gradients are obtained.

[0049] The ingots prepared in this embodiment were tested, and the data are shown in Table 3.

[0050] Table 3 Data from Example 3

[0051] Comparative Example 1 1. For example Figure 3 As shown in Figure d, two HT700P and HT700T alloy electrodes were prepared using induction melting. The electrodes were conventional cylindrical with a nominal diameter of 320 mm. The two electrodes were then welded together to obtain a single electrode. 2. The electrodes are loaded into the furnace for vacuum consumable melting, with priority given to remelting the corresponding components of HT700T. The melting rate is set to 2.60 kg / min, and there is no program interference when passing through the welding position. 3. Post-casting processing: After vacuum arc remelting, the finished ingot is obtained.

[0052] Table 4 Comparative Example 1 Data

[0053] Comparative Example 2 1. Two HT700P and HT700T alloy electrodes were prepared using induction melting. The electrodes were conventional cylindrical with a nominal diameter of 320 mm. The two electrodes were then welded together to obtain a single electrode. 2. The electrodes are loaded into the furnace for vacuum consumable melting, with priority given to remelting the corresponding components of HT700T. The melting rate is set to 3.20 kg / min, and there is no program interference when passing through the welding position. 3. Post-casting processing: After vacuum consumable melting, finished ingots are obtained.

[0054] Table 5 Comparative Example 2 Data

[0055] Based on the data from the above embodiments and comparative examples, the following conclusions can be drawn: Regarding the axial distribution length of the composition gradient, the ingots of Examples 1-3 have axial distribution lengths of 420 mm, 420 mm, and 530 mm, respectively, all achieving the design target length (400-500 mm). In contrast, Comparative Examples 1 and 2 have axial distribution lengths of only 180 mm and 240 mm, respectively, with no controllable gradient variation. This indicates that the combined consumable electrode and transition section axial dimensions designed in this invention can stably achieve the target length of the ingot's axial composition gradient, significantly outperforming conventional welding electrodes.

[0056] Regarding the accuracy of melting rate control, the melting rate deviation of Examples 1 to 3 was within ±10%, while Comparative Examples 1 and 2 reached ±30% and ±50%, respectively. This indicates that the present invention can significantly improve the stability of the melting process through the coordinated control of "structured electrode" and "programmed melting rate", so that the actual melting rate accurately matches the design requirements.

[0057] Regarding compositional uniformity, the elemental range at the edge / center / center of the ingot composition transition section in Examples 1-3 was 0.07 wt%, while that in Comparative Examples 1 and 2 was 0.14 wt%. This demonstrates that the present invention effectively suppresses compositional segregation, resulting in a more uniform radial compositional distribution in the ingot, and significantly superior overall metallurgical quality compared to conventional methods.

[0058] In summary, this invention achieves precise control of the axial composition gradient distribution of the ingot by reverse designing the interface size of the transition section of the combined consumable electrode and combining it with a melting rate control formula based on the electrode diameter. At the same time, it ensures the stability of the melting process and the composition uniformity of the ingot, overcoming the defects of low composition control accuracy, limited gradient range, and poor interface metallurgical quality in the prior art.

[0059] This invention proposes designing and fabricating two alloy electrodes with specific geometric interfaces for combination. By controlling the physical characteristics of the electrodes at the interface and combining this with directional control of the melting rate, the heat input during melting is regulated, thereby influencing the molten pool and achieving stable control of the composition gradient. Firstly, a transition section between the two alloy electrodes is designed on the electrodes to achieve a stable transition in the melting process, improving the controllability of the length of the composition gradient distribution. Secondly, by rationally setting the electrode melting rate to complement the impact of electrode structure changes on the solidification process, composition distribution control can be further enhanced. By systematically coordinating changes in electrode geometry with real-time adjustments to the melting rate, the changes in electrode structure can be used as a setting basis, and the melting rate adjustment can be used as a means of fine compensation and stable control, jointly achieving stable and precise programmable control of the molten pool morphology. This systematic method, through the synergy of "structured electrodes" and "programmed melting rates," actively designs and controls the composition distribution, thereby achieving axial composition gradient distribution in the ingot.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the present invention.

Claims

1. A self-consumable melting method for preparing axial composition gradient HT700P-HT700T ingots, characterized in that, Includes the following steps: S1. Based on the target composition gradient distribution along the ingot axis, and combined with the mathematical model relating the vacuum consumable arc melting process parameters to the depth of the molten pool, the interface of the combined consumable electrode is designed in reverse. The combined consumable electrode has a transition section. The axial dimensions and interface geometric parameters of the transition section are designed. The combined consumable electrode includes a first alloy electrode and a second alloy electrode. S2. According to the design results of S1, prepare a first alloy electrode and a second alloy electrode with the interface respectively, and connect the first alloy electrode and the second alloy electrode through the interface to obtain a combined consumable electrode. S3. The combined consumable electrode is placed in a vacuum consumable arc furnace for remelting. During the remelting process, the first alloy electrode is connected to the auxiliary electrode, and remelting begins from the end of the second alloy electrode. According to the preset mapping relationship between the electrode consumption position and the process parameter group, the power supply system is adaptively adjusted when melting reaches the transfer section to control the electrode melting rate. S4. After remelting, the furnace is cooled to obtain HT700P-HT700T ingots with axial composition gradient.

2. The method according to claim 1, characterized in that, In step S1, the interface is a mortise and tenon structure, including a male end set at the end of the first alloy electrode and a female end set at the end of the second alloy electrode.

3. The method according to claim 2, characterized in that, The male end is a truncated conical or cylindrical shape.

4. The method according to claim 3, characterized in that, When the male end is a truncated conical shape, its minimum diameter D i With the maximum diameter D f The ratio ranges from 0.3 to 1, and the maximum diameter D f Not greater than the electrode diameter De.

5. The method according to claim 1, characterized in that, In step S1, the axial dimension Z of the transition section is Z = L_target(z) - H S ; Where L_target(z) is the target length of the axial composition gradient segment of the ingot, and H S The steady-state molten pool depth is defined as that used in vacuum consumable arc melting with combined electrodes.

6. The method according to claim 1, characterized in that, In step S3, the electrode melting rate is controlled according to the following formula: V e =6.273-15.13·0.996 De In the formula, V e D is the electrode melting rate. e The diameter is the electrode diameter.

7. The method according to claim 6, characterized in that, The electrode diameter ranges from 260 to 840 mm.

8. The method according to claim 1, characterized in that, In step S2, the first alloy electrode and the second alloy electrode have the same nominal outer diameter, and their actual outer diameter deviation is ≤30 mm.

9. The method according to claim 1, characterized in that, The first alloy electrode is HT700P, and the second alloy electrode is HT700T.

10. An axial composition gradient HT700P-HT700T ingot, characterized in that, It is prepared by the method described in any one of claims 1 to 9.

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