Preparation method of super-large-size high-temperature alloy ingot and application thereof
By using a triple process and a specific annealing process to prepare ultra-large high-temperature alloy ingots, and combining multi-fire forging and gradient heating to prepare high-temperature alloy cylindrical blanks, the problems of low production efficiency and small number of finished products in the existing technology have been solved, and the effect of efficient preparation of large-size high-temperature alloy cylindrical blanks has been achieved.
Patent Information
- Application Number
- CN202611437956.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-09-16
- Publication Date
- 2026-11-03
AI Technical Summary
The existing GH4169 alloy ingot production process suffers from problems such as low production efficiency and easy occurrence of macro and micro segregation, resulting in high production costs and difficulty in preparing large-size high-temperature alloy billets, which affects the localization process.
A triple process (vacuum induction melting, electroslag remelting, and vacuum consumable remelting) combined with red-heat annealing at a specific temperature and homogenization diffusion annealing was used to prepare an ultra-large high-temperature alloy ingot with a diameter of 660 mm. A high-temperature alloy cylindrical billet with a diameter of φ690 mm was prepared by multi-fire forging and gradient heating.
It achieves precise control of composition and uniform structure of ultra-large high-temperature alloy ingots, reduces production costs, improves production efficiency and yield, and can produce multiple drum shafts in one go, solving the problems of low production efficiency and small number of finished products in existing technologies.
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Figure CN123027459A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of high-temperature alloy smelting technology, and in particular to a method for preparing ultra-large high-temperature alloy ingots and their applications. Background Technology
[0002] GH4169 alloy is a Ni-Cr-Fe based precipitation hardening wrought superalloy with good comprehensive properties in the temperature range of -253℃ to 700℃. Its yield strength below 650℃ is the highest among wrought superalloys. It also has good fatigue resistance, radiation resistance, oxidation resistance, and corrosion resistance. It has been widely used in aerospace, nuclear energy, petroleum industry and extrusion molds.
[0003] The high-pressure turbine drum shafts used in the main aero engines currently in service are made of GH4169 alloy. The general production process for GH4169 alloy billets is as follows: vacuum induction melting, electroslag remelting, vacuum arc remelting (φ508mm ingot), homogenization diffusion annealing, fast forging (φ300 bar), and machining. This production process suffers from low production efficiency and is prone to macroscopic and microscopic segregation. Due to the limitations of the billet size and weight, forging plants can only produce 1 to 2 pieces per forging operation, and the processing time is long, resulting in low production efficiency and severely restricting the subsequent overall assembly of the engine. If forging or extrusion plants need to produce more drum shafts at once, larger billet diameters and weights are required. GH4169 has a high degree of alloying and contains a large number of easily segregating elements such as Nb, Al, and Ti, which makes GH4169 alloy ingots prone to metallurgical defects such as macroscopic and microscopic segregation. Moreover, the larger the ingot, the more severe the segregation. Therefore, the largest arc remelting ingot commonly used in China is currently only about φ508mm. When the ingot size is ≥ φ660mm, due to solidification segregation, porosity and other factors, the bar stock is prone to defects such as macroscopic segregation, inclusions and inconsistencies in structure. Coupled with the low efficiency, low yield and poor batch quality stability of the small ingots used for billets, the domestic high-temperature alloy materials are not only inferior in quality to foreign products, but also 1.5 times more expensive, which seriously affects the localization process of high-temperature alloys.
[0004] Therefore, in order to improve the production efficiency and batch quality of drum shafts and reduce production costs, it is urgent to develop a larger GH4169 alloy ingot (φ660mm) to prepare GH4169 alloy cylinder blanks with larger size and greater weight. Summary of the Invention
[0005] To address the aforementioned problems, this invention provides a method for preparing ultra-large high-temperature alloy ingots and its application. Through process parameter design, high-quality preparation of ultra-large high-temperature alloy ingots (φ660mm) and ultra-large high-temperature alloy cylindrical blanks (outer diameter φ690mm, inner diameter φ262mm) is achieved, effectively solving the smelting segregation problem of ultra-large ingots, improving production efficiency and yield, and effectively reducing production costs.
[0006] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows: In a first aspect, the present invention provides a method for preparing ultra-large-scale high-temperature alloy ingots, comprising the following steps: S1. Vacuum induction melting of raw materials, casting, to obtain electrodes; S2. The electrode is electroslag remelted, then heated and annealed at 1140℃~1180℃ to obtain an electroslag ingot. S3. Under a helium atmosphere, the electroslag ingot is vacuum consumable remelted to obtain a consumable ingot; S4. The consumable ingot is subjected to homogenization diffusion annealing to obtain an ultra-large high-temperature alloy ingot. The diameter of the ultra-large high-temperature alloy ingot is 660mm ± 15mm.
[0007] It should be noted that "red-hot conveying" in S2 is a widely used professional term in the metallurgical industry, referring to the process of directly conveying steel ingots or continuously cast billets to the next process while they are still red-hot and at a high temperature after demolding.
[0008] Compared to existing technologies, the method for preparing ultra-large-sized high-temperature alloy ingots (hereinafter referred to as ingots) provided by this invention utilizes a three-stage process (vacuum induction melting + electroslag remelting + vacuum arc remelting) for smelting, followed by homogenization diffusion annealing, to obtain ultra-large-sized high-temperature alloy ingots with a diameter of 660mm±20mm. The hot-heat annealing process at a specific temperature after electroslag remelting effectively reduces the core-surface temperature difference and residual thermal stress in large-section electroslag ingots, preventing cracks, bending, or misalignment during subsequent machining, flattening, and vacuum arc remelting loading. Simultaneously, the hot-heat annealing process allows easily segregating elements such as Nb, Ti, and Al to undergo diffusion mitigation before entering the vacuum arc remelting process, reducing the risk of segregation during subsequent solidification of the arc remelted ingot.
[0009] Preferably, the ultra-large-scale high-temperature alloy ingot comprises the following chemical composition by mass percentage: C≤0.08%, Cr 17.0%~21.0%, Mo 2.8%~3.3%, Nb 4.75%~5.5%, Ti 0.65%~1.15%, Al 0.2%~0.8%, Ni 50.0%~55.0%, Co≤1.0%, Mn≤0.35%, with the balance being Fe and unavoidable impurity elements.
[0010] More preferably, the ultra-large-scale high-temperature alloy ingot further includes the following chemical composition by mass percentage: B≤0.006%, Si≤0.15%, Cu≤0.1%, S≤0.0013%, P≤0.015%, O≤0.003% and N≤0.01%.
[0011] More preferably, the ultra-large-scale high-temperature alloy ingot comprises the following chemical composition by mass percentage: C 0.021%~0.025%, Cr 17.5%~18.5%, Mo 2.9%~3.0%, Nb 5.2%~5.45%, Ti 0.95%~1.0%, Al 0.45%~0.55%, Ni 52.5%~54.0%, Co 0.2%~0.3%, Mn≤0.2%, B 0.003%~0.0045%, Si≤0.15%, Cu≤0.1%, S≤0.001%, P≤0.006%, Mg 0.0002%~0.001%, As≤0.003%, Pb≤0.0002%, Se≤0.0003%, Bi≤0.00003%, Ta≤0.05%, Ag≤0.0005%, O 0.0002%~0.0008%, N 0.003%~0.005%, Ca≤0.003%, with the balance being Fe and unavoidable impurity elements.
[0012] Preferably, in S1, the raw materials include 60% to 70% high-temperature alloy recycled material and 30% to 40% virgin material by mass.
[0013] Generally, high-temperature alloy smelting uses alloys such as Ni, Fe, C, Cr, Mo, and Co (primary raw materials) as raw materials. This invention selects a specific proportion of recycled high-temperature alloys as raw materials, significantly reducing production costs and improving the utilization rate of scarce strategic resources while further mitigating the purity risks associated with primary smelting. Since high-temperature alloys contain a large number of expensive elements (such as Ni, Mo, and Co), recycling recycled materials reduces dependence on expensive primary metals, directly lowering batching costs. Furthermore, high-quality recycled high-temperature alloys have already undergone a complete smelting and solidification process, resulting in generally good macroscopic purity. Compared to using a variety of complex primary raw materials, using recycled materials with clearly defined compositions reduces impurity introduction, lowers the burden of deoxidation and desulfurization, and helps stabilize metallurgical quality.
[0014] Preferably, in S1, the conditions for vacuum induction melting include: the temperature of the melting stage is 1450℃~1510℃; the temperature of the refining stage is 1470℃~1490℃, the refining time is ≥120min; and the tapping temperature is 1470℃~1500℃.
[0015] More preferably, in S1, the refining stage lasts for 120 min to 200 min, and the absolute pressure is ≤1 Pa.
[0016] Preferably, in S1, the diameter of the electrode is 430mm ± 15mm.
[0017] Preferably, in S2, the melting rate of the electroslag remelting is 6 kg / min to 8 kg / min.
[0018] Through numerous experiments, this invention has found that if the melting rate is too low (such as the existing technology's 4.5 kg / min to 5.5 kg / min), the surface quality of the electroslag ingot after electroslag remelting is poor.
[0019] More preferably, in S2, the voltage of the electroslag remelting is 40V~45V and the current is 11000A~11400A.
[0020] This invention ensures a stable melting rate by controlling the voltage and current of electroslag remelting.
[0021] Preferably, in S2, the annealing time is ≥15h.
[0022] In a further preferred embodiment, in S2, the specific steps of the annealing include: annealing at 1150℃~1170℃, holding at that temperature for 15h~20h, cooling in the furnace to below 200℃, and then air-cooling after removal from the furnace to obtain the electroslag ingot.
[0023] Through extensive experiments, this invention has found that if electroslag ingots are cooled directly without annealing, or are completely cooled before annealing, the electroslag ingots are prone to cracking due to high internal stress, which in turn leads to significant melting rate fluctuations during subsequent vacuum arc remelting, resulting in segregation or spalling.
[0024] Preferably, in S2, the diameter of the electroslag ingot is 590mm ± 15mm.
[0025] Preferably, in S3, the conditions for vacuum consumable remelting include: a melting rate of 4.5 kg / min to 6 kg / min during the arc initiation stage; a melting rate of 4 kg / min to 5 kg / min and a droplet rate of 3.5 Hz to 5 Hz during the stable melting stage; and a melting rate of 3.4 kg / min to 4.2 kg / min and a droplet rate of 5 Hz to 7 Hz during the feeding stage.
[0026] Preferably, in S3, the conditions for vacuum consumable remelting include: a helium flow rate of 0.1 L / min to 0.2 L / min during the arc initiation stage, a helium flow rate of 0.3 L / min to 0.4 L / min during the stable melting stage, and a helium flow rate of 0.2 L / min to 0.3 L / min during the feeding stage.
[0027] In the vacuum arc remelting process, this invention reduces the fluctuation of the molten pool depth by using different He gas cooling rates, melting rates and droplet rates at different stages, and suppresses the enrichment of easily segregating elements such as Nb, Ti and Al during the solidification process of large cross sections. This solves the problems of deep molten pool, long solidification time and aggravated segregation caused by ultra-large ingots, and achieves the effect of stable control of smelting.
[0028] Preferably, in step S3, after the vacuum consumable remelting is completed, the process further includes: furnace cooling for 70 to 90 minutes, demolding, and cooling under a cover for more than 48 hours to obtain the consumable ingot.
[0029] Preferably, in S4, the specific steps of the homogenization diffusion annealing include: holding the consumable ingot at 1150℃~1170℃ for 35h~45h, then holding it at 1190℃~1210℃ for 80h~110h, then cooling it in the furnace to below 600℃, and then air-cooling it to obtain the ultra-large high-temperature alloy ingot.
[0030] Through extensive experiments, this invention has found that if the holding time during homogenization diffusion annealing is insufficient, it can lead to segregation defects such as black spots on the ingot.
[0031] Secondly, the present invention provides a method for preparing an ultra-large-scale high-temperature alloy cylindrical billet, comprising the following steps: Step a: Prepare ultra-large high-temperature alloy ingots according to the preparation method described above. Step b: The ultra-large high-temperature alloy ingot is forged in multiple forging cycles. The initial forging temperature is 1080℃~1120℃, the heating temperature for each forging cycle is 900℃~1100℃, and the holding time for each heating cycle is 3h~5h, to obtain the bar stock. Step c: The bar is subjected to gradient heating and punched to obtain an ultra-large high-temperature alloy cylindrical billet; The outer diameter of the ultra-large high-temperature alloy cylindrical blank is 690mm ± 5mm.
[0032] This invention provides a method for preparing ultra-large-sized high-temperature alloy cylindrical billets (hereinafter referred to as billets). The method involves heating an ingot and forging it through multiple heats to obtain a bar. Then, holes are drilled to ultimately produce a cylindrical billet for drum shafts (i.e., an ultra-large-sized high-temperature alloy cylindrical billet) with qualified composition and satisfactory surface and internal microstructure. By limiting the conditions of the multiple heats forging, the bar can be forged through, reducing the loose microstructure in the core and ensuring qualified microstructure at both ends. This invention uses gradient heating for punching (rather than direct high-temperature punching), which effectively precipitates the δ phase that hinders grain growth. By changing the content and distribution of the δ phase microstructure inside the billet, the method aims to prevent grain growth during the punching process.
[0033] Preferably, in S5, the multi-fire forging includes four-fire upsetting and drawing.
[0034] More preferably, in S5, in the four-stage upsetting and drawing processes, the heating temperature of the first upsetting is 1080℃~1120℃, the deformation is 30%~35%, and the final forging temperature is 950℃~980℃; the heating temperature of the first drawing is 1050℃~1100℃, the deformation is 12%~20%, and the final forging temperature is 930℃~950℃; the heating temperature of the second upsetting is 1030℃~1080℃, the deformation is 38%~50%, and the final forging temperature is 920℃~940℃; the heating temperature of the second drawing is 980℃~1020℃, the deformation is 30%~40%, and the final forging temperature is... The heating temperature for the third upsetting is 890℃~910℃; the heating temperature for the third upsetting is 1000℃~1040℃, the deformation is 35%~48%, and the final forging temperature is 915℃~935℃; the heating temperature for the third drawing is 900℃~980℃, the deformation is 30%~40%, and the final forging temperature is 860℃~890℃; the heating temperature for the fourth upsetting is 1000℃~1040℃, the deformation is 35%~48%, and the final forging temperature is 915℃~935℃; the heating temperature for the fourth drawing is 980℃~1020℃, the deformation is 25%~35%, and the final forging temperature is 890℃~910℃.
[0035] In the multi-stage forging process, the first two stages are mainly upsetting with large deformation to generate sufficient triaxial compressive stress in the core of the ingot to compress the central porosity and shrinkage cavity; the third stage breaks up the dendritic structure and pulls apart the segregation zone through elongation and directional deformation; the final stage controls grain growth through shaping in a lower temperature zone to ensure that the inner hole area does not crack during subsequent punching.
[0036] Preferably, in S5, the diameter of the rod is 710mm ± 5mm.
[0037] Preferably, in step S5, after the multi-fire forging is completed, the bar is further subjected to machining and end-flattening to obtain a bar with a diameter of 690mm±5mm and a length of 910mm±50mm.
[0038] Preferably, in S6, the specific steps of gradient heating include: heating the bar to 900℃~920℃, holding it at that temperature for 3.5h~4.5h, then raising the temperature to 970℃~1000℃, holding it at that temperature for 3.5h~4.5h, and then punching it.
[0039] Preferably, in S6, the punching is performed using a closed die.
[0040] Preferably, in S6, the inner diameter of the ultra-large high-temperature alloy cylindrical blank is 262mm ± 5mm.
[0041] The present invention has the following beneficial effects: This invention provides a method for preparing ultra-large-sized high-temperature alloy ingots and their applications. Through the design of process parameters for each step, the method ensures precise composition control, uniform microstructure, and absence of metallurgical defects such as macroscopic segregation in the φ660mm ultra-large-sized high-temperature alloy ingot. Furthermore, a φ690mm ultra-large-sized high-temperature alloy cylindrical blank is prepared using multi-fire forging and closed-loop punching methods. Using this cylindrical blank, 14 to 16 finished drum shafts can be produced in a single extrusion molding process, far exceeding the 1 to 2 drum shafts produced by existing processes (existing ingots are small, resulting in a small amount of finished cylindrical blanks, and drum shafts can only be produced through die forging). This significantly improves production efficiency and reduces production costs. Attached Figure Description
[0042] Figure 1 This is a diagram showing the liquid surface state of molten steel after vacuum induction melting in Embodiment 1 of the present invention; Figure 2 This is a cross-sectional sample diagram of the electroslag ingot in Embodiment 1 of the present invention; Figure 3 This is a longitudinal cross-sectional sampling diagram of the electroslag ingot in Embodiment 1 of the present invention; Figure 4 This is a sample diagram of the transverse cross section of the bar in Embodiment 1 of the present invention; Figure 5 This is a longitudinal cross-sectional sample diagram of the bar in Embodiment 1 of the present invention; Figure 6 This is a micrograph of a cross-sectional sample taken from the bar in Embodiment 1 of the present invention; Figure 7 This is a micrograph of a longitudinal section sample of the bar in Embodiment 1 of the present invention; Figure 8 This is a metallographic diagram of the ultra-large high-temperature alloy cylindrical billet in Embodiment 1 of the present invention; Figure 9 This is a diagram of carbide inclusions in the ultra-large high-temperature alloy cylindrical billet in Embodiment 1 of the present invention; Figure 10 This is a cross-sectional view of the bar in Embodiment 2 of the present invention. Figure 11 This is a longitudinal cross-sectional sampling diagram of the bar in Embodiment 2 of the present invention; Figure 12 This is a micrograph of a cross-sectional sample of the bar in Embodiment 2 of the present invention; Figure 13 This is a micrograph of a longitudinal section sample of the bar in Embodiment 2 of the present invention; Figure 14 This is a cross-sectional view of the bar in Embodiment 3 of the present invention. Figure 15This is a metallographic diagram of the ultra-large high-temperature alloy cylindrical billet in Embodiment 3 of the present invention; Figure 16 This is a cross-sectional view of the bar in Embodiment 5 of the present invention. Figure 17 This is a longitudinal cross-sectional sampling diagram of the bar in Embodiment 5 of the present invention; Figure 17 The red box indicates the defective part; Figure 17 The lathe is used for machining longitudinal sections, so there are rings of machining marks. Figure 18 This is a micrograph of a cross-sectional sample of the bar in Embodiment 5 of the present invention; Figure 18 Medium-bright white indicates black spots; Figure 19 This is a micrograph of a longitudinal section sample of the bar in Embodiment 5 of the present invention; Figure 19 Medium-bright white indicates black spots; Figure 20 This is a cross-sectional view of the bar in Embodiment 6 of the present invention. Figure 21 This is a longitudinal cross-sectional sampling diagram of the bar in Embodiment 6 of the present invention; Figure 22 This is a micrograph of a cross-sectional sample of the bar in Embodiment 6 of the present invention; Figure 23 This is a micrograph of a longitudinal section sample of the bar in Embodiment 6 of the present invention; Figure 24 This is a cross-sectional sample diagram of the electroslag ingot in Comparative Example 1 of the present invention; Figure 25 This is a longitudinal cross-sectional sample diagram of the electroslag ingot in Comparative Example 2 of the present invention; Figure 25 The red box indicates the defective part; Figure 26 This is a cross-sectional sample of the bar in Comparative Example 3 of the present invention; Figure 27 This is a metallographic diagram of the ultra-large high-temperature alloy cylindrical billet in Comparative Example 4 of the present invention. Detailed Implementation
[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0044] Unless otherwise specified, all raw materials used in the embodiments of this invention can be obtained through commercial channels.
[0045] Example 1 This embodiment provides a method for preparing an ultra-large-size high-temperature alloy cylindrical billet, including the following steps: S1. Raw materials (65% high-temperature alloy return material and 35% primary alloy materials such as Ni, Fe, C, Cr, Mo, and Co) are added to a 12t vacuum induction furnace for vacuum induction melting. The melting stage temperature is 1480℃; the refining stage temperature is 1480℃, the absolute pressure is 0.85Pa, and the refining time is 180min; after the composition inspection is qualified, the steel is tapped at 1480℃ and cast to obtain an electrode with a diameter of φ430mm.
[0046] Photos of molten steel after vacuum induction melting, as shown Figure 1 As shown, there is no slag on the surface of the molten steel after vacuum induction melting.
[0047] S2. The electrode is placed in a protective atmosphere electroslag furnace for electroslag remelting at a melting rate of 7 kg / min, a voltage of 43V, and a current of 11200A. Then, it is heated and annealed at 1160℃ for 18 hours, and then cooled in the furnace to below 200℃. After being removed from the furnace and air-cooled, an electroslag ingot with a diameter of 590mm is obtained.
[0048] Visual inspection revealed that the surface quality of the electroslag ingot was good. Samples were taken from the transverse and longitudinal sections of the electroslag ingot for further observation. Figures 2-3 As shown, no cracks were found inside.
[0049] S3. Under a helium atmosphere, the machined and flattened electroslag ingot was placed in a φ660mm consumable crystallizer for vacuum consumable remelting. It was then cooled in the furnace for 80 minutes, demolded, and cooled under a cover for 48 hours to obtain a φ660mm consumable ingot. During the vacuum consumable remelting process, the helium flow rate was 0.15 L / min and the melting rate was 5.2 kg / min during the arc initiation stage; the helium flow rate was 0.34 L / min and the melting rate was 4.5 kg / min during the stable melting stage, with a droplet rate of 4.0 Hz; and the helium flow rate was 0.25 L / min and the melting rate was 3.8 kg / min during the feeding stage, with a droplet rate of 6.0 Hz.
[0050] During the vacuum arc remelting process, key curves such as voltage, melting rate, and current remained stable without fluctuations. Visual inspection revealed that the surface quality of the arc remelting ingot was good.
[0051] S4. The consumable ingot is subjected to homogenization diffusion annealing, first held at 1160℃ for 40h, then held at 1200℃ for 100h, and then cooled in the furnace to below 600℃, and then air-cooled to obtain an ultra-large high-temperature alloy ingot with a diameter of φ660mm.
[0052] The ultra-large-scale high-temperature alloy ingots contain the following chemical composition by mass percentage: C 0.024%, Cr 18.01%, Mo 2.94%, Nb 5.32%, Ti 0.98%, Al 0.49%, Ni 53.30%, Co 0.26%, Mn 0.13%, B 0.0033%, Si 0.13%, Cu 0.06%, S 0.0004%, P 0.002%, Mg 0.0006%, As≤0.003%, Pb≤0.0002%, Se≤0.0003%, Bi≤0.00003%, Ta≤0.05%, Ag≤0.0005%, O 0.0005%, N 0.004%, Ca≤0.003%, with the balance being Fe and unavoidable impurity elements.
[0053] S5. The ultra-large high-temperature alloy ingot undergoes four-stage upsetting and drawing. The first upsetting is performed at 1100℃ for 4 hours, with a deformation of 32% and a final forging temperature of 965℃. The first drawing is performed at 1080℃ for 4 hours, with a deformation of 16% and a final forging temperature of 940℃. The second upsetting is performed at 1050℃ for 4 hours, with a deformation of 43% and a final forging temperature of 930℃. The second drawing is performed at 1000℃ for 4 hours, with a deformation of 35% and a final forging temperature of 940℃. The first forging temperature was 900℃; the second forging temperature was 1020℃, held for 4 hours, with a deformation of 41%, and the final forging temperature was 925℃; the third forging temperature was 940℃, held for 4 hours, with a deformation of 35%, and the final forging temperature was 875℃; the fourth forging temperature was 1020℃, held for 4 hours, with a deformation of 41%, and the final forging temperature was 925℃; the fourth forging temperature was 1000℃, held for 4 hours, with a deformation of 30%, and the final forging temperature was 900℃, yielding a φ710mm black bar. The black bar was then machined and flattened to obtain a φ690mm×910mm bar.
[0054] Sampling and observation of the transverse and longitudinal sections of the bar, such as... Figures 4-7 As shown, no black spots, white spots, or segregation defects were found, and there were no loose defects.
[0055] S6. The bar stock is loaded into the furnace and subjected to gradient heating. First, it is heated to 910℃ and held for 4 hours. Then, it is heated to 990℃ and held for 4 hours. After that, it is punched with a closed mold to obtain an ultra-large high-temperature alloy cylinder billet with an outer diameter of φ660mm and an inner diameter of φ262mm.
[0056] Sampling and observation of the metallographic structure of ultra-large high-temperature alloy cylindrical billets, such as... Figures 8-9 As shown, its grain size is uniform and there are no carbide inclusions.
[0057] Example 2 This embodiment provides a method for preparing an ultra-large-size high-temperature alloy cylindrical billet, including the following steps: S1. Raw materials (70% high-temperature alloy return material and 30% primary alloy materials such as Ni, Fe, C, Cr, Mo, and Co) are added to a 12t vacuum induction furnace for vacuum induction melting. The melting stage temperature is 1510℃; the refining stage temperature is 1490℃, the absolute pressure is 0.88Pa, and the refining time is 130min; after the composition inspection is qualified, the steel is tapped at 1500℃ and cast to obtain an electrode with a diameter of φ430mm.
[0058] No slag floats on the surface of the molten steel after vacuum induction melting.
[0059] S2. The electrode is placed in a protective atmosphere electroslag furnace for electroslag remelting at a melting rate of 6 kg / min, a voltage of 42V, and a current of 11300A. Then it is heated and annealed at 1150℃ for 20 hours, and then cooled in the furnace to below 200℃. After being removed from the furnace and air-cooled, an electroslag ingot with a diameter of 590mm is obtained.
[0060] Visual inspection revealed that the surface quality of the electroslag ingot was good. Sampling and observation of the transverse and longitudinal sections of the electroslag ingot showed no internal cracks.
[0061] S3. Under a helium atmosphere, the machined and flattened electroslag ingot was placed in a φ660mm consumable crystallizer for vacuum consumable remelting. It was then cooled in the furnace for 70 minutes, demolded, and cooled under a cover for 50 hours to obtain a φ660mm consumable ingot. During the vacuum consumable remelting process, the helium flow rate was 0.1 L / min and the melting rate was 4.5 kg / min during the arc initiation stage; the helium flow rate was 0.4 L / min and the melting rate was 5 kg / min during the stable melting stage, with a droplet rate of 5 Hz; and the helium flow rate was 0.2 L / min and the melting rate was 3.4 kg / min during the feeding stage, with a droplet rate of 5 Hz.
[0062] During the vacuum arc remelting process, key curves such as voltage, melting rate, and current remained stable without fluctuations. Visual inspection revealed that the surface quality of the arc remelting ingot was good.
[0063] S4. The consumable ingot is subjected to homogenization diffusion annealing, first held at 1170℃ for 35h, then held at 1190℃ for 110h, and then cooled in the furnace to below 600℃, and then air-cooled to obtain an ultra-large high-temperature alloy ingot with a diameter of φ660mm.
[0064] The ultra-large-scale high-temperature alloy ingots contain the following chemical composition by mass percentage: C 0.021%, Cr 17.42%, Mo 2.93%, Nb 5.41%, Ti 0.96%, Al 0.52%, Ni 52.57%, Co 0.28%, Mn 0.12%, B 0.003%, Si 0.11%, Cu 0.06%, S 0.0005%, P 0.003%, Mg 0.0008%, As≤0.003%, Pb≤0.0002%, Se≤0.0003%, Bi≤0.00003%, Ta≤0.05%, Ag≤0.0005%, O 0.0007%, N 0.003%, Ca≤0.003%, with the balance being Fe and unavoidable impurity elements.
[0065] S5. The ultra-large high-temperature alloy ingot undergoes four-stage upsetting and drawing. The first upsetting is performed at 1120℃ for 3.2 hours, with a deformation rate of 35% and a final forging temperature of 950℃. The first drawing is performed at 1050℃ for 4.8 hours, with a deformation rate of 13% and a final forging temperature of 950℃. The second upsetting is performed at 1030℃ for 4.8 hours, with a deformation rate of 40% and a final forging temperature of 920℃. The second drawing is performed at 1020℃ for 3.2 hours, with a deformation rate of 40%. The final forging temperature was 910℃; the third upsetting temperature was 1000℃, held for 5 hours, with a deformation of 46%, and the final forging temperature was 915℃; the third drawing temperature was 980℃, held for 3 hours, with a deformation of 30%, and the final forging temperature was 890℃; the fourth upsetting temperature was 1040℃, held for 3 hours, with a deformation of 46%, and the final forging temperature was 915℃; the fourth drawing temperature was 1020℃, held for 3 hours, with a deformation of 35%, and the final forging temperature was 890℃, yielding a φ710mm black bar. The black bar was then machined and flattened to obtain a φ690mm×950mm bar.
[0066] Sampling and observation were performed on the transverse and longitudinal sections of the bar, and the results are as follows: Figures 10-13 As shown, no black spots, white spots, or segregation defects were found, and there were no loose defects.
[0067] S6. The bar stock is loaded into the furnace and subjected to gradient heating. First, it is heated to 900℃ and held for 4.5 hours. Then, it is heated to 970℃ and held for 4 hours. After that, it is punched with a closed mold to obtain an ultra-large high-temperature alloy cylinder billet with an outer diameter of φ660mm and an inner diameter of φ262mm.
[0068] Metallographic observation of ultra-large high-temperature alloy cylindrical billets revealed that they had uniform grain size and no carbide inclusions.
[0069] Example 3 This embodiment provides a method for preparing an ultra-large-scale high-temperature alloy cylindrical billet, including the following steps: S1. Raw materials (60% high-temperature alloy return material and 40% primary alloy materials such as Ni, Fe, C, Cr, Mo, and Co) are added to a 12t vacuum induction furnace for vacuum induction melting. The melting stage temperature is 1450℃; the refining stage temperature is 1470℃, the absolute pressure is 0.84Pa, and the refining time is 200min. After the composition inspection is qualified, the steel is tapped at 1470℃ and cast to obtain an electrode with a diameter of φ430mm.
[0070] No slag floats on the surface of the molten steel after vacuum induction melting.
[0071] S2. The electrode is placed in a protective atmosphere electroslag furnace for electroslag remelting at a melting rate of 8 kg / min, a voltage of 44V, and a current of 11350A. Then, it is heated and annealed at 1170℃ for 16 hours, and then cooled in the furnace to below 200℃. After being removed from the furnace and air-cooled, an electroslag ingot with a diameter of 590mm is obtained.
[0072] Visual inspection revealed that the surface quality of the electroslag ingot was good. Sampling and observation of the transverse and longitudinal sections of the electroslag ingot showed no internal cracks.
[0073] S3. Under a helium atmosphere, the machined and flattened electroslag ingot was placed in a φ660mm consumable crystallizer for vacuum consumable remelting. It was then cooled in the furnace for 90 minutes, demolded, and cooled under a cover for 48 hours to obtain a φ660mm consumable ingot. During the vacuum consumable remelting process, the helium flow rate was 0.2 L / min and the melting rate was 6 kg / min during the arc initiation stage; the helium flow rate was 0.3 L / min and the melting rate was 4 kg / min during the stable melting stage, with a droplet rate of 3.5 Hz; and the helium flow rate was 0.3 L / min and the melting rate was 4.2 kg / min during the feeding stage, with a droplet rate of 7 Hz.
[0074] During the vacuum arc remelting process, key curves such as voltage, melting rate, and current remained stable without fluctuations. Visual inspection revealed that the surface quality of the arc remelting ingot was good. Sampling and observation of the transverse and longitudinal sections of the arc remelting ingot revealed no black spots, white spots, or segregation defects.
[0075] S4. The consumable ingot is subjected to homogenization diffusion annealing, first held at 1150℃ for 45h, then held at 1210℃ for 85h, and then cooled in the furnace to below 600℃, and then air-cooled to obtain an ultra-large high-temperature alloy ingot with a diameter of φ660mm.
[0076] The ultra-large-scale high-temperature alloy ingots contain the following chemical composition by mass percentage: C 0.024%, Cr 17.56%, Mo 2.98%, Nb 5.24%, Ti 0.99%, Al 0.45%, Ni 53.5%, Co 0.22%, Mn 0.13%, B 0.004%, Si 0.10%, Cu 0.07%, S 0.0007%, P 0.005%, Mg 0.0002%, As≤0.003%, Pb≤0.0002%, Se≤0.0003%, Bi≤0.00003%, Ta≤0.05%, Ag≤0.0005%, O 0.0002%, N 0.005%, Ca≤0.003%, with the balance being Fe and unavoidable impurity elements.
[0077] S5. The ultra-large high-temperature alloy ingot undergoes four-stage upsetting and drawing. The first upsetting is performed at 1080℃ for 4.8 hours, with a deformation rate of 30%, and a final forging temperature of 980℃. The first drawing is performed at 1100℃ for 3.2 hours, with a deformation rate of 20%, and a final forging temperature of 930℃. The second upsetting is performed at 1080℃ for 3.2 hours, with a deformation rate of 50%, and a final forging temperature of 940℃. The second drawing is performed at 980℃ for 4.8 hours, with a deformation rate of 30%. The final forging temperature was 890℃; the third upsetting temperature was 1040℃, held for 3.2 hours, with a deformation of 36%, and the final forging temperature was 935℃; the third drawing temperature was 900℃, held for 5 hours, with a deformation of 40%, and the final forging temperature was 860℃; the fourth upsetting temperature was 1000℃, held for 5 hours, with a deformation of 36%, and the final forging temperature was 935℃; the fourth drawing temperature was 980℃, held for 5 hours, with a deformation of 25%, and the final forging temperature was 910℃, yielding a φ710mm black bar. The black bar was then machined and end-faced to obtain a φ690mm×860mm bar.
[0078] Sampling and observation of the transverse cross section of the bar were performed, and the results are as follows: Figure 14 As shown, no looseness defects were found.
[0079] S6. The bar stock is loaded into the furnace and subjected to gradient heating. First, it is heated to 920℃ and held for 3.5 hours. Then, it is heated to 1000℃ and held for 4 hours. After that, it is punched with a closed mold to obtain an ultra-large high-temperature alloy cylinder billet with an outer diameter of φ660mm and an inner diameter of φ262mm.
[0080] The metallographic structure of the ultra-large high-temperature alloy cylindrical billet was sampled and observed, and the results are as follows: Figure 15 As shown, its grain size is uniform and there are no carbide inclusions.
[0081] Example 4 This embodiment provides a method for preparing ultra-large-scale high-temperature alloy ingots, similar to Embodiment 1, except that the melting rate of electroslag remelting in S2 is 5 kg / min, and the voltage and current are modified accordingly. Specifically, it includes the following steps: S2. The electrode of Example 1 was placed in a protective atmosphere electroslag furnace for electroslag remelting at a melting rate of 5 kg / min, a voltage of 42V, and a current of 11200A. Then it was heated and annealed at 1160℃ for 18h, and then cooled in the furnace to below 200℃. After being removed from the furnace and air-cooled, an electroslag ingot with a diameter of 590mm was obtained.
[0082] Observation of the electroslag ingots obtained by S2 revealed some slag grooves, peeling, and crusting on the surface, as well as a small number of longitudinal / transverse hot cracks, local depressions, and slag splashing. (These surface defects will not affect product performance, but may cause cracking during subsequent forging processes, affecting the forming rate.)
[0083] S3~S4 are the same as S3~S4 in Example 1, and will not be described again.
[0084] Example 5 This embodiment provides a method for preparing an ultra-large high-temperature alloy cylindrical billet, similar to Embodiment 1, except that: during the S3 vacuum arc remelting process, the helium flow rate is 0.05 L / min in the arc initiation stage, the stabilization melting stage, and the feeding stage, the melting rate is 5.2 kg / min, and the droplet rate is 4.0%. Specifically, it includes the following steps: S3. Under a helium atmosphere, the electroslag ingot of Example 1, after being machined and flattened, was placed in a φ660mm consumable crystallizer for vacuum consumable remelting. The helium flow rate was 0.05 L / min, the melting rate was 5.2 kg / min, and the droplet rate was 4.0%. Then, it was cooled in the furnace for 80 min, demolded, and cooled under a cover for 48 h to obtain a φ660mm consumable ingot.
[0085] During the vacuum arc remelting process, key curves such as voltage, melting rate, and current remain stable without fluctuations.
[0086] S4~S5 are the same as S4~S5 in Example 1, and will not be described again.
[0087] Sampling and observation of the transverse and longitudinal sections of the bar, such as... Figures 16-19 As shown, black spots and high Nb segregation defects were found. Since the black spot defects formed during the preparation of consumable ingots cannot be eliminated in the homogenization diffusion annealing of S4, the bars forged in subsequent multiple heats will have corresponding defects.
[0088] S6 is the same as S6 in Example 1, and will not be described again.
[0089] Example 6 This embodiment provides a method for preparing an ultra-large-sized high-temperature alloy cylindrical billet, similar to Embodiment 1, except that: during the S3 vacuum arc remelting process, the helium flow rate is 0.5 L / min during the arc initiation stage, the stabilization melting stage, and the feeding stage, the melting rate is 3.0 kg / min, and the droplet rate is 4.0%. Specifically, it includes the following steps: S3. Under a helium atmosphere, the electroslag ingot of Example 1, after being machined and flattened, was placed in a consumable crystallizer with a diameter of φ660mm for vacuum consumable remelting. The helium flow rate was 0.5 L / min, the melting rate was 3.0 kg / min, and the droplet rate was 4.0%. Then, it was cooled in the furnace for 80 min, demolded, and cooled under a cover for 48 h to obtain a consumable ingot with a diameter of φ660mm.
[0090] During the vacuum arc remelting process, key curves such as voltage, melting rate, and current remain stable without fluctuations.
[0091] S4~S5 are the same as S4~S5 in Example 1, and will not be described again.
[0092] Sampling and observation of the transverse and longitudinal sections of the bar, such as... Figures 20-23 As shown, white spots and low Nb segregation defects were found. Since the white spot defects formed during the preparation of consumable ingots cannot be eliminated in the homogenization diffusion annealing of S4, the bars forged in subsequent multiple heats will have corresponding defects.
[0093] S6 is the same as S6 in Example 1, and will not be described again.
[0094] Comparative Example 1 This comparative example provides a method for preparing ultra-large high-temperature alloy ingots, similar to Example 1, except that annealing is not performed after electroslag remelting in S2. Specifically, it includes the following steps: S2. The electrode from Example 1 was placed in a protective atmosphere electroslag furnace for electroslag remelting at a melting rate of 7 kg / min, a voltage of 43V, and a current of 11200A. Then, it was cooled in the furnace to below 200°C and then air-cooled to obtain an electroslag ingot with a diameter of 590mm.
[0095] Sampling and observation of the transverse and longitudinal sections of the electroslag ingot, such as... Figure 24 As shown, cracks were found inside.
[0096] S3~S4 are the same as S3~S4 in Example 1, and will not be described again.
[0097] During the vacuum arc remelting process, significant fluctuations were observed in key curves such as voltage, melting rate, and current, indicating quality risks such as segregation caused by chipping.
[0098] Comparative Example 2 This comparative example provides a method for preparing ultra-large-sized high-temperature alloy ingots, similar to Example 1, except that in S2, annealing is performed after complete cooling following electroslag remelting (i.e., not hot-melt). Specifically, it includes the following steps: S2. The electrode from Example 1 was placed in a protective atmosphere electroslag furnace for electroslag remelting at a melting rate of 7 kg / min, a voltage of 43V, and a current of 11200A. Then, it was cooled in the furnace to below 200°C and then removed from the furnace and air-cooled. It was then annealed at 1160°C for 18 hours, cooled in the furnace to below 200°C, and then removed from the furnace and air-cooled to obtain an electroslag ingot with a diameter of 590mm.
[0099] Sampling and observation of the transverse and longitudinal sections of the electroslag ingot, such as... Figure 25 As shown, cracks were found inside.
[0100] S3~S4 are the same as S3~S4 in Example 1, and will not be described again.
[0101] During the vacuum arc remelting process, significant fluctuations were observed in key curves such as voltage, melting rate, and current, indicating quality risks such as segregation caused by chipping.
[0102] Comparative Example 3 This comparative example provides a method for preparing an ultra-large high-temperature alloy cylindrical billet, similar to Example 1, except that in S5, the heating temperature for each heating cycle is increased by 20°C, and the heating time is shortened from 4 hours to 2 hours. Specifically, it includes the following steps: S5. The ultra-large high-temperature alloy ingot from Example 1 is subjected to four-stage upsetting and drawing. The first upsetting is performed at 1120°C for 2 hours, with a deformation of 32% and a final forging temperature of 985°C. The first drawing is performed at 1100°C for 2 hours, with a deformation of 16% and a final forging temperature of 960°C. The second upsetting is performed at 1070°C for 2 hours, with a deformation of 43% and a final forging temperature of 950°C. The second drawing is performed at 1020°C for 2 hours, with a deformation of 35% and a final forging temperature of 985°C. The forging temperature was 920℃; the third upsetting temperature was 1040℃, held for 2 hours, with a deformation of 41%, and the final forging temperature was 945℃; the third drawing temperature was 960℃, held for 2 hours, with a deformation of 35%, and the final forging temperature was 895℃; the fourth upsetting temperature was 1040℃, held for 2 hours, with a deformation of 41%, and the final forging temperature was 945℃; the fourth drawing temperature was 1020℃, held for 2 hours, with a deformation of 30%, and the final forging temperature was 920℃, yielding a φ710mm black bar. The black bar was then machined and end-faced to obtain a φ690mm×910mm bar.
[0103] Sampling and observation of the transverse cross section of the bar, such as... Figure 26As shown, a looseness defect was found.
[0104] S6 is the same as S6 in Example 1, and will not be described again.
[0105] Comparative Example 4 This comparative example provides a method for preparing an ultra-large high-temperature alloy cylindrical billet, similar to Example 1, except that in step S6, the bar is directly heated to 1000°C for punching. Specifically, it includes the following steps: S6. The bar stock of Example 1 is loaded into the furnace and heated at 1000℃ for 8 hours. Then, it is punched with a closed mold to obtain an ultra-large high-temperature alloy cylinder billet with an outer diameter of φ660mm and an inner diameter of φ262mm.
[0106] Sampling and observation of the metallographic structure of ultra-large high-temperature alloy cylindrical billets, such as... Figure 27 As shown, its grain size is not uniform.
[0107] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing ultra-large-scale high-temperature alloy ingots, characterized in that, Includes the following steps: S1. Vacuum induction melting of raw materials, casting, to obtain electrodes; S2. The electrode is electroslag remelted, then heated and annealed at 1140℃~1180℃ to obtain an electroslag ingot. S3. Under a helium atmosphere, the electroslag ingot is vacuum consumable remelted to obtain a consumable ingot. S4. The consumable ingot is subjected to homogenization diffusion annealing to obtain an ultra-large high-temperature alloy ingot. The diameter of the ultra-large high-temperature alloy ingot is 660mm ± 15mm.
2. The method for preparing ultra-large-scale high-temperature alloy ingots as described in claim 1, characterized in that, The ultra-large-scale high-temperature alloy ingot comprises the following chemical composition by mass percentage: C≤0.08%, Cr 17.0%~21.0%, Mo 2.8%~3.3%, Nb 4.75%~5.5%, Ti 0.65%~1.15%, Al 0.2%~0.8%, Ni 50.0%~55.0%, Co≤1.0%, Mn≤0.35%, with the balance being Fe and unavoidable impurity elements.
3. The method for preparing ultra-large-scale high-temperature alloy ingots as described in claim 1 or 2, characterized in that, In S2, the melting rate of the electroslag remelting is 6 kg / min to 8 kg / min; In S2, the annealing time is ≥15h; In S3, the conditions for vacuum consumable remelting include: a melting rate of 4.5 kg / min to 6 kg / min during the arc initiation stage; a melting rate of 4 kg / min to 5 kg / min and a droplet rate of 3.5 Hz to 5 Hz during the stable melting stage; a melting rate of 3.4 kg / min to 4.2 kg / min and a droplet rate of 5 Hz to 7 Hz during the feeding stage; a helium flow rate of 0.1 L / min to 0.2 L / min during the arc initiation stage; a helium flow rate of 0.3 L / min to 0.4 L / min during the stable melting stage; and a helium flow rate of 0.2 L / min to 0.3 L / min during the feeding stage.
4. The method for preparing ultra-large-scale high-temperature alloy ingots as described in claim 3, characterized in that, In S1, the raw materials include 60% to 70% high-temperature alloy recycled material and 30% to 40% virgin material by mass. In S2, the voltage of the electroslag remelting is 40V~45V and the current is 11000A~11400A; In S2, the specific steps of the annealing include: annealing at 1150℃~1170℃, holding at that temperature for 15h~20h, cooling in the furnace to below 200℃, and then air cooling after removal from the furnace to obtain the electroslag ingot.
5. The method for preparing ultra-large-scale high-temperature alloy ingots as described in claim 1, characterized in that, In S1, the conditions for vacuum induction melting include: the temperature of the melting stage is 1450℃~1510℃; the temperature of the refining stage is 1470℃~1490℃, the absolute pressure is ≤1Pa, the refining time is ≥120min; and the tapping temperature is 1470℃~1500℃. In S4, the specific steps of the homogenization diffusion annealing include: holding the consumable ingot at 1150℃~1170℃ for 35h~45h, then holding it at 1190℃~1210℃ for 80h~110h, then cooling it in the furnace to below 600℃, and then air-cooling it to obtain the ultra-large high-temperature alloy ingot.
6. The method for preparing ultra-large-scale high-temperature alloy ingots as described in claim 1, characterized in that, In S1, the diameter of the electrode is 430mm ± 15mm; In S2, the diameter of the electroslag ingot is 590mm ± 15mm.
7. A method for preparing an ultra-large high-temperature alloy cylindrical billet, characterized in that, Includes the following steps: Step a: Prepare an ultra-large high-temperature alloy ingot according to the preparation method of any one of claims 1 to 6; Step b: The ultra-large high-temperature alloy ingot is forged in multiple forging cycles. The initial forging temperature is 1080℃~1120℃, the heating temperature for each forging cycle is 900℃~1100℃, and the holding time for each heating cycle is 3h~5h, to obtain the bar stock. Step c: The bar is subjected to gradient heating and punched to obtain an ultra-large high-temperature alloy cylindrical billet; The outer diameter of the ultra-large high-temperature alloy cylindrical blank is 690mm ± 5mm.
8. The method for preparing ultra-large-scale high-temperature alloy cylindrical billets as described in claim 7, characterized in that, In S5, the multi-fire forging process includes four-fire upsetting and drawing. In S6, the specific steps of gradient heating include: heating the bar to 900℃~920℃, holding it at that temperature for 3.5h~4.5h, then raising the temperature to 970℃~1000℃, holding it at that temperature for 3.5h~4.5h, and then punching the hole.
9. The method for preparing ultra-large-scale high-temperature alloy cylindrical blanks as described in claim 8, characterized in that, In S5, during the four-stage upsetting and drawing processes, the heating temperature for the first upsetting is 1080℃~1120℃, the deformation is 30%~35%, and the final forging temperature is 950℃~980℃; the heating temperature for the first drawing is 1050℃~1100℃, the deformation is 12%~20%, and the final forging temperature is 930℃~950℃; the heating temperature for the second upsetting is 1030℃~1080℃, the deformation is 38%~50%, and the final forging temperature is 920℃~940℃; the heating temperature for the second drawing is 980℃~1020℃, the deformation is 30%~40%, and the final forging temperature is 8... The heating temperature for the third upsetting is 90℃~910℃; the heating temperature for the third upsetting is 1000℃~1040℃, the deformation is 35%~48%, and the final forging temperature is 915℃~935℃; the heating temperature for the third drawing is 900℃~980℃, the deformation is 30%~40%, and the final forging temperature is 860℃~890℃; the heating temperature for the fourth upsetting is 1000℃~1040℃, the deformation is 35%~48%, and the final forging temperature is 915℃~935℃; the heating temperature for the fourth drawing is 980℃~1020℃, the deformation is 25%~35%, and the final forging temperature is 890℃~910℃.
10. The method for preparing ultra-large-scale high-temperature alloy cylindrical billets as described in claim 7, characterized in that, In S5, the diameter of the rod is 710mm ± 5mm; In S6, the inner diameter of the ultra-large high-temperature alloy cylindrical blank is 262mm ± 5mm.