A preparation method of large-size GH4169 alloy electroslag ingot
By using a five-element slag system and optimized electroslag remelting process parameters, the problems of elemental segregation and surface defects in large-size GH4169 alloy electroslag ingots were solved, and high yield and good microstructure uniformity of electroslag ingots were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- XIAN JUNENG SUPERALLOY MATERIAL TECH CO LTD
- Filing Date
- 2026-04-03
- Publication Date
- 2026-05-29
AI Technical Summary
Existing technologies for preparing large-size GH4169 alloy electroslag ingots suffer from severe element segregation and numerous surface defects, making it difficult to balance the internal and surface quality of the alloy.
Electroslag remelting (ESR) using a five-element slag system (CaF2, CaO, Al2O3, TiO2, MgO) was employed. The ESR process parameters were optimized, the ESR melting rate and slag swing were controlled, and ESR was combined with a protective atmosphere to prepare large-size GH4169 alloy ESR ingots.
It significantly improves the compositional uniformity and surface quality of electroslag ingots, avoids defects such as slag grooves and steel penetration points, and improves the yield and overall performance.
Smart Images
Figure CN122105162A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of high-temperature alloy smelting technology, and relates to a method for preparing large-size GH4169 alloy electroslag casting ingots. Background Technology
[0002] GH4169 is an age-hardening nickel-based wrought superalloy with excellent tensile strength, yield strength, creep strength, and high-temperature fatigue and creep resistance. Therefore, it has become a widely used alloy material in aerospace, nuclear power, petroleum, and chemical industries.
[0003] Currently, domestically, GH4169 is typically produced using vacuum induction melting (VIM) + electroslag remelting (ESR), vacuum induction melting (VIM) + vacuum arc remelting (VAR), or vacuum induction melting (VIM) + ESR + VAR processes. Compared to dual-stage VIM+VAR and triple-stage VIM+ESR+VAR processes with VAR as the final step, ESR ingots are less prone to white spot defects and have a higher yield. However, the slag scale affects lateral heat transfer in the ingot, reducing the solidification rate and causing more severe elemental segregation in large-size ESR ingots compared to arc remelting ingots of the same size. To reduce segregation and the probability of black spots, the melting rate and energy input need to be reduced. This causes a drop in the temperature of the slag pool and molten pool, resulting in high viscosity and poor fluidity of the nickel-based alloy. This further leads to defects such as slag grooves and steel penetration points on the surface of large-size GH4169 alloys, making it difficult to achieve both surface and internal quality of the alloy.
[0004] Therefore, there is an urgent need to develop a method for preparing large-size GH4169 alloy electroslag casting ingots to solve the above problems. Summary of the Invention
[0005] The purpose of this invention is to overcome the shortcomings of the prior art and propose a method for preparing large-size GH4169 alloy electroslag ingots. This invention provides a five-element slag system and a matching smelting method, which on the one hand reduces the electroslag melting rate and alleviates the tendency for component segregation, and on the other hand improves the surface quality of the electroslag ingot, avoiding defects such as slag grooves and steel penetration points on the surface of the alloy electroslag ingot. This results in large-size GH4169 alloy electroslag ingots with high yield, good compositional uniformity, and no black spot defects.
[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention discloses a method for preparing large-size GH4169 alloy electroslag ingots, comprising the following steps: S1. According to the target composition ratio of each element in the GH4169 alloy, the raw materials corresponding to Ni, Fe, Nb, Cr, Mo and C are first mixed to obtain a first mixture; then the raw materials corresponding to Al, Ti, B and P are mixed to obtain a second mixture; the first mixture is sequentially melted and refined once, then cooled, and the second mixture is added for a second melt, and then cast to obtain an electroslag electrode. S2. The surface of each of the electroslag electrodes is polished, and then electroslag remelting is carried out in a protective atmosphere using a pentagonal slag system. After cooling, a large-size GH4169 alloy electroslag ingot can be obtained.
[0007] Specifically, in S1, the target composition ratios of each element in the GH4169 alloy are as follows: C≤0.08%, Cr: 17.0~21.0%, Ni: 50.0~55.0%, Al: 0.2~0.8%, Ti: 0.65~1.15%, Mo: 2.8~3.3%, Nb: 4.75~5.50%, B≤0.006%, P≤0.015%, Fe: balance.
[0008] More specifically, in S1, the composition ratio of some elements in the GH4169 alloy is preferably: C: 0.020~0.030%, Nb: 4.75~5.30%, Ti: 0.90~1.10%.
[0009] Specifically, in S1, the Ni element is preferably a nickel plate; the Fe element is preferably metallic iron; the Nb element is preferably a niobium strip; the Cr element is preferably metallic chromium; the Mo element is preferably a molybdenum strip; and the C element is preferably a graphite block.
[0010] Specifically, in S1, the Al element is preferably aluminum granules; the Ti element is preferably titanium blocks; the B element is preferably NiB master alloy; and the P element is preferably NiP master alloy.
[0011] Specifically, in S2, the polishing process requires polishing the surface of the electroslag electrode until a metallic luster is exposed, and there must be no oxide scale present.
[0012] Specifically, in S2, the cooling process is preferably performed for 40 to 90 minutes.
[0013] Furthermore, in S1, the temperature of the first melting and cleaning is 1480~1500℃, and the first vacuum degree is ≤10Pa.
[0014] Specifically, during the first melting and cleaning process, the power of the vacuum induction furnace is increased to 600~800kw to achieve the first melting and cleaning temperature.
[0015] Furthermore, in S1, the refining temperature is 1460~1500℃, the second vacuum degree is <0.5Pa, and the time is 50~70min.
[0016] Specifically, electromagnetic stirring must be kept running throughout the refining process.
[0017] Furthermore, in S1, the temperature of the secondary melting is 1460~1480℃, and the third vacuum degree is ≤10Pa.
[0018] Furthermore, in S1, the pouring temperature is 1500~1550℃.
[0019] Specifically, the ingot mold used in the casting process needs to be preheated to 300~500℃ to avoid surface defects such as cracks and oxidation in the electroslag ingot during the casting process.
[0020] Furthermore, in S2, the smelting process of the protective atmosphere electroslag remelting is protected by argon gas, and the overpressure inside the furnace is 0.2 bar.
[0021] Furthermore, in S2, the mass ratio of each component in the five-element slag system is as follows: CaF2 56~66%, CaO 10~20%, Al2O3 12~22%, TiO2 0.5~4.5%, MgO 2.5~6.5%.
[0022] Furthermore, in S2, the electrode size used in the electroslag remelting is Φ310~360mm, the slag amount is 50~80kg, the melting rate is 180~220 kg / h, and the slag swing is 1.0~2.0 mOhm.
[0023] Specifically, in the electroslag remelting process, the nominal inner diameter of the crystallizer is preferably 450 mm.
[0024] Furthermore, in S2, 20-30% of the total slag is added before power is supplied during electroslag remelting, and the remaining slag is added 5-10 minutes after power is supplied, and the addition is completed within 30 minutes.
[0025] Compared with the prior art, the present invention has the following beneficial effects: This invention uses a pentagonal slag system composed of CaF2, CaO, Al2O3, TiO2 and MgO as the electroslag for electroslag remelting, and optimizes the proportion of each component in the pentagonal slag system. At the same time, during the electroslag remelting process, the electroslag melting rate is controlled at 180~220 kg / h and the slag swing is controlled at 1.0~2.0 mOhm, which can effectively improve the heat transfer and solidification conditions during the electroslag remelting process.
[0026] By synergistically controlling the slag composition and electroslag remelting process parameters, it is beneficial to reduce the viscosity of the molten pool, promote the removal and homogenization of inclusions, improve the purity of the molten metal and the uniformity of the solidification structure, and thus make the obtained electroslag ingots have excellent surface quality, uniform slag skin thickness, and no obvious slag grooves, steel penetration points and other surface defects. In addition, no abnormal defects such as black spots were observed in the low magnification structure after forging, and the element distribution at the head and tail of the ingot was uniform with small compositional differences.
[0027] This invention significantly improves the compositional and microstructure uniformity of ingots, which is beneficial for increasing the yield and overall performance of large-size GH4169 alloys. Attached Figure Description
[0028] The accompanying drawings are incorporated in and form part of this specification, and together with the description serve to explain the principles of the invention.
[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0030] Figure 1 This is a flowchart of the preparation method of the present invention; Figure 2 This is a schematic diagram showing the location of the sampled sections of the bars obtained by forging each electroslag casting ingot in Examples 1-3; Figure 3 This is a low-magnification microstructure image of a cross-section taken from position W of the bar material obtained by forging the electroslag casting ingot in Example 1; Figure 4 This is a low-magnification microstructure image of a cross-section taken from position T of the bar material obtained by forging the electroslag ingot in Example 1; Figure 5 This is a photograph of the 450mm GH4169 electroslag ingot prepared in Example 1. Figure 6 This is a photograph of the 450mm GH4169 electroslag ingot prepared in Example 2. Figure 7 This is a photograph of the 450mm GH4169 electroslag ingot prepared in Example 3. Figure 8 This is a photograph of a 450mm GH4169 electroslag ingot, which is a comparative example. Figure 9 This is a low-magnification microstructure diagram of the bar material obtained by forging the electroslag ingot in Comparative Example 1. Detailed Implementation
[0031] Exemplary embodiments will now be described in detail. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples consistent with some aspects of the invention as detailed in the appended claims.
[0032] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.
[0033] Example 1 like Figure 1 As shown, this embodiment provides a method for preparing large-size GH4169 alloy electroslag ingots, including the following steps: S1. According to the target composition ratio of each element in the GH4169 alloy, Ni plate, Fe metal, Nb strip, Cr metal, Mo strip and graphite block are first mixed to obtain a first mixture; then Al bean, Ti block, NiB master alloy and NiP master alloy are mixed to obtain a second mixture; then, the first mixture is first melted and cleaned at a temperature of 1500℃ and a first vacuum degree of 10Pa; after melting and cleaning, it is refined, and electromagnetic stirring is turned on throughout the refining process, the refining temperature is 1500℃, the second vacuum degree is 0.1Pa, and the time is 50min; after refining, the molten steel obtained from the first mixture is cooled to 1480℃, and then the second mixture is added for a second melting and cleaning, the third vacuum degree of the second melting and cleaning is 10Pa; the preheated ingot mold is placed in the ingot mold chamber, the molten steel after the second melting and cleaning is heated to 1550℃ and poured into the ingot mold, and after cooling, an electroslag electrode is obtained.
[0034] Specifically, in S1, the mass percentage of each element in the electroslag electrode is shown in Table 1: Table 1. Mass percentage (wt%) of each element in the electroslag electrode of Example 1 Ni Cr Mo Fe Al C Nb Ti 52.0 18.0 2.90 Remain 0.6 0.027 5.3 1.0 Specifically, in S1, the ingot mold is preheated to 500°C.
[0035] S2. Grind the sides of each of the electroslag electrodes obtained in S1 until there is no oxide scale, and grind the head and tail end faces until they are 100% visible. Then, place the large-size electroslag electrodes in an electroslag remelting furnace, purge the furnace with argon to an overpressure of 0.2 bar, and perform electroslag remelting. After cooling, a large-size GH4169 alloy electroslag ingot can be obtained.
[0036] Specifically, in S2, the electroslag remelting process uses a five-element slag system. The total mass of the slag in the five-element slag system is 80 kg, and the mass percentages of each component are as follows: CaF2 accounts for 66% (52.8 kg), CaO accounts for 10% (8 kg), Al2O3 accounts for 17% (13.6 kg), TiO2 accounts for 4.5% (3.6 kg), and MgO accounts for 2.5% (2 kg).
[0037] Specifically, in S2, the large-size electroslag electrode has a size of Φ360mm.
[0038] Specifically, in S2, the parameters of the electroslag remelting furnace are set as follows: melting rate 220 kg / h, slag swing 2 mOhm.
[0039] Specifically, in S2, the nominal inner diameter of the crystallizer is 450 mm.
[0040] Specifically, in S2, before electroslag remelting and power transmission, 30% (24 kg) of the total mass of the five-element slag system is added. After power transmission for 5 minutes, the remaining 70% (56 kg) of slag is added to the slag pool within 30 minutes.
[0041] Specifically, in S2, the cooling process takes 90 minutes.
[0042] Example 2 The preparation method in this embodiment is the same as that in Example 1, except that: In S1: The temperature of the first melting and cleaning process is 1490℃, and the first vacuum degree is 6Pa; The refining process is carried out at a temperature of 1480℃, a second vacuum degree of 0.3Pa, and a time of 60min. During the second smelting process, the molten steel obtained from the first smelting is cooled to 1470℃, and the third vacuum degree is 6Pa; The ingot mold is preheated to 400°C; The pouring temperature is 1530℃.
[0043] Specifically, in S1, the mass percentage of each element in the electroslag electrode is shown in Table 2: Table 2. Mass percentage (wt%) of each element in the electroslag electrode of Example 2 Ni Cr Mo Fe Al C Nb Ti 52.4 17.8 2.93 Remain 0.58 0.028 5.4 1.1 In S2: The total mass of the slag in the five-element slag system is 68 kg, and the mass percentages of each component are as follows: CaF2 56% (38 kg), CaO 19% (13 kg), Al2O3 21% (14.28 kg), TiO2 0.5% (0.34 kg), and MgO 3.5% (2.38 kg). The large-size electroslag electrode has a size of Φ340mm; The parameters of the electroslag remelting furnace are set as follows: melting rate 200 kg / h, slag swing 1.5 mOhm; Before electroslag remelting and power transmission, 20% (13.6 kg) of the total mass of the five-element slag system is added. After power transmission for 7 minutes, the remaining 80% (54.4 kg) of slag is added to the slag pool within 30 minutes. The cooling process takes 60 minutes.
[0044] Example 3 The preparation method in this embodiment is the same as that in Example 1, except that: In S1: The temperature of the first melting and cleaning process is 1480℃, and the first vacuum degree is 1Pa; The refining process is carried out at a temperature of 1460℃, a second vacuum degree of 0.45Pa, and a time of 70min. During the second smelting process, the molten steel obtained from the first smelting is cooled to 1460°C, and the third vacuum degree is 1 Pa; The mass percentage of each element in the electroslag electrode is shown in Table 3. Table 3. Mass percentage (wt%) of each element in the electroslag electrode of Example 3 Ni Cr Mo Fe Al C Nb Ti 52.0 17.9 2.95 Remain 0.57 0.026 5.39 1.09 The ingot mold is preheated to 300°C; The pouring temperature is 1500℃.
[0045] In S2: The total mass of the slag in the five-element slag system is 50 kg, and the mass percentages of each component are as follows: CaF2 accounts for 62.5% (mass of 31.25 kg), CaO accounts for 16% (mass of 8 kg), Al2O3 accounts for 12% (mass of 6 kg), TiO2 accounts for 3% (mass of 1.5 kg), and MgO accounts for 6.5% (mass of 3.25 kg). The large-size electroslag electrode has a size of Φ310mm; The parameters of the electroslag remelting furnace are set as follows: melting rate 180 kg / h, slag swing 1 mOhm; Before electroslag remelting and power transmission, 25% (12.5 kg) of the total mass of the five-element slag system is added. After power transmission for 10 minutes, the remaining 75% (37.5 kg) of slag is added to the slag pool within 30 minutes. The cooling process takes 40 minutes.
[0046] Comparative Example 1 The preparation method in this comparative example is the same as that in Example 1, except that: In S1: The mass percentage of each element in the electroslag electrode is shown in Table 4. Table 4. Mass percentage (wt%) of each element in the electroslag electrode of Comparative Example 1 Ni Cr Mo Fe Al C Nb Ti 52.0 18.0 2.90 Remain 0.6 0.027 5.3 1.0 In S2: The large-size electroslag electrode has a size of Φ320mm; The crystallizer has a diameter of Φ450mm; The total mass of the five-element slag system is 70 kg; The melting rate of the electroslag remelting furnace is set to 240 kg / h.
[0047] Comparative Example 2 The preparation method of the electroslag electrode described in this comparative example is the same as that in Example 1, except that: In S1, the mass percentage of each element in the electroslag electrode is shown in Table 5: Table 5. Mass percentage (wt%) of each element in the electroslag electrode of Comparative Example 2 Ni Cr Mo Fe Al C Nb Ti 52.2 17.9 3.0 Remain 0.55 0.025 5.2 1.03 In S2, the electroslag remelting process uses imported Wacker 2059 commercial slag material commonly used in GH4169 alloy smelting. The weight percentages of its slag components are as follows: CaF2 48±2%, CaO 20±2%, Al2O3 22±2%, TiO2 3.0±0.6%, MgO 5.0±0.8%.
[0048] To verify the effectiveness of the present invention, according to Figure 2 As shown in the table, samples were taken from the W and T positions of the electroslag ingots prepared in Examples 1-3, and the proportions of each alloying element at the W and T positions were measured. The results are shown in Table 5. Table 6. Proportion of alloying elements at positions T and W in Examples 1-3 As shown in Table 6, the mass fractions of Ni, Cr, Mo, Fe, Al, C, Nb, and Ti at T and W (corresponding to the head and tail of the ingot, respectively) in Examples 1-3 are very close, with minimal deviation. This indicates that the electroslag remelting method provided by this invention can effectively control the compositional segregation of large-size GH4169 alloy electroslag ingots, resulting in good overall compositional uniformity of the ingot. Furthermore, compared with the corresponding electrode composition, no significant abnormal fluctuations in the Al and Ti compositions of the electroslag ingots described in each example were observed, proving that the electroslag remelting process parameters provided by this invention are properly controlled, effectively avoiding the burning and segregation of alloying elements.
[0049] like Figure 3 , Figure 4 The images show low-magnification microstructure images of sample sections taken from the tail (W) and head (T) positions of the bar material obtained by forging the electroslag casting ingot in Example 1. As can be seen from the microstructure images, both sections exhibit a dense and uniform macrostructure, without obvious porosity, inclusions or segregation bands, and without metallurgical defects such as black spots and white spots; indicating that the metallurgical quality of the casting ingot is good and the solidification process is stable.
[0050] Figures 5-7 The figures shown are actual images of the GH4169 alloy electroslag ingots prepared in Examples 1-3 of the present invention. As can be seen from the figures, the surface quality of each electroslag ingot is good, the slag skin is thin and uniform, and there are no surface defects such as steel penetration points and slag grooves. They can be forged directly without peeling. This shows that the present invention can significantly improve the yield of large-size GH4169 alloy electroslag ingots and improve production efficiency.
[0051] Figure 8 As shown in the figure, when the electroslag melting rate of the GH4169 alloy prepared for Comparative Example 1 is adjusted to a range of 180~220 kg / h (the electroslag melting rate in this comparative example is 240 kg / h), the surface of the obtained electroslag ingot has local steel penetration points, and the overall surface quality is significantly worse than that of Example 1. Figure 9 The image shows the low-magnification microstructure of the upper part of the bar after the electroslag ingot is forged into a bar. As can be seen from the image, there are obvious black spots in the core of the bar. Normally, if black spots appear in a bar, the entire bar is considered scrap.
[0052] In Comparative Example 2, the physical properties of Wacker 2059 slag system, such as melting point, viscosity and conductivity, are not well matched with the preparation process of large-size ingots, and the melting characteristics and electrical parameters are not stable. As a result, defects such as slag grooves, annular bands and slag adhesion are generated on the surface of the prepared ingots, which will further cause internal metallurgical quality risks.
[0053] In summary, the five-element slag system and matching electroslag remelting process parameters provided by this invention can produce electroslag ingots with uniform structure, stable composition, and excellent surface quality. The forged bars are free from metallurgical defects such as porosity, segregation bands, black spots, and white spots, which can effectively meet the requirements of high-end manufacturing equipment.
[0054] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement 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.
[0055] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.
Claims
1. A method for preparing large-size GH4169 alloy electroslag casting ingots, characterized in that, Includes the following steps: S1. According to the target composition ratio of each element in the GH4169 alloy, the raw materials corresponding to Ni, Fe, Nb, Cr, Mo and C are first mixed to obtain a first mixture; then the raw materials corresponding to Al, Ti, B and P are mixed to obtain a second mixture; the first mixture is sequentially melted and refined once, then cooled, and the second mixture is added for a second melt, and then cast to obtain an electroslag electrode. S2. The surface of the electroslag electrode is polished, and then electroslag remelting is carried out in a protective atmosphere using a pentagonal slag system. After cooling, a large-size GH4169 alloy electroslag ingot can be obtained.
2. The method for preparing a large-size GH4169 alloy electroslag ingot according to claim 1, characterized in that, In S1, the temperature of the first melting and cleaning is 1480~1500℃, and the first vacuum degree is ≤10Pa.
3. The method for preparing a large-size GH4169 alloy electroslag ingot according to claim 1, characterized in that, In S1, the refining temperature is 1460~1500℃, the second vacuum degree is <0.5Pa, and the time is 50~70min.
4. The method for preparing a large-size GH4169 alloy electroslag ingot according to claim 1, characterized in that, In S1, the temperature of the secondary melting is 1460~1480℃, and the third vacuum degree used is ≤10Pa.
5. The method for preparing a large-size GH4169 alloy electroslag ingot according to claim 1, characterized in that, In S1, the pouring temperature is 1500~1550℃.
6. The method for preparing a large-size GH4169 alloy electroslag ingot according to claim 1, characterized in that, In S2, the smelting process of the protective atmosphere electroslag remelting is protected by argon gas, and the overpressure inside the furnace is 0.2 bar.
7. The method for preparing a large-size GH4169 alloy electroslag ingot according to claim 1, characterized in that, In S2, the mass ratio of each component in the five-element slag system is as follows: CaF2 56~66%, CaO 10~20%, Al2O3 12~22%, TiO2 0.5~4.5%, MgO 2.5~6.5%.
8. The method for preparing a large-size GH4169 alloy electroslag ingot according to claim 1, characterized in that, In S2, the electrode size used in the electroslag remelting is Φ310~360mm, the slag amount is 50~80kg, the melting rate is 180~220 kg / h, and the slag swing is 1.0~2.0 mOhm.
9. The method for preparing a large-size GH4169 alloy electroslag ingot according to claim 8, characterized in that, In S2, 20-30% of the total slag is added before power is supplied for electroslag remelting. The remaining slag is added 5-10 minutes after power is supplied and is completed within 30 minutes.