A zirconium-containing alloy and a vacuum induction melting method thereof

Abstract

This invention belongs to the field of alloy preparation and discloses a zirconium-containing alloy and its vacuum induction melting method. The zirconium-containing alloy comprises, by mass percentage: C: 0.26%~0.30%, Si: 0.40%~0.50%, Mn: 0.20%~0.30%, V: 1.30%~1.50%, Zr: 0.20%~0.35%, Ni: 37.00%~38.00%, with the balance being Fe. The method includes the steps of raw material selection, charging, melting, refining, alloying, and tapping. In the raw material selection step, the total oxygen content in the raw materials is controlled to be no higher than 0.018%, and the total sulfur content is no higher than 0.0010%. Ni, C, V, and Fe sources are added in the charging step, while Zr, Si, and Mn sources are added in the alloying step. The refining step controls the vacuum level at 0.3~0.8 Pa, the refining temperature at 1480℃~1530℃, and the refining time at 90~150 min. The alloying step controls the molten steel temperature at 1380℃~1430℃, and alloying is carried out under Ar purging conditions of 22000~28000 Pa. The tapping temperature is 1580℃~1600℃. This method can solve the technical problem of accurate and stable control of zirconium content during vacuum induction melting of zirconium-containing alloys.

Description

Technical Field

[0001] This invention belongs to the field of alloy preparation, specifically relating to a zirconium-containing alloy and its vacuum induction melting method. Background Technology

[0002] Zirconium-containing alloys, thanks to the superior properties of zirconium, have broad application prospects in machinery manufacturing, aerospace components, and high-end molds. However, zirconium, as a highly reactive metallic element, readily combines with elements such as oxygen and sulfur during smelting to form zirconium oxysulfide inclusions. This not only significantly reduces the zirconium yield but also affects key indicators such as the alloy's mechanical properties, thermal expansion properties, and corrosion resistance. Furthermore, zirconium is prone to burn-off at high temperatures. The method of addition, addition temperature, addition time, and process parameters such as vacuum degree and temperature control during smelting all have a crucial impact on the degree of zirconium burn-off and the yield.

[0003] Existing vacuum induction melting processes for zirconium-containing alloys commonly suffer from unstable zirconium yield and difficulty in precise control. While some processes attempt to improve yield by adjusting the timing or amount of zirconium addition, they lack a systematic method for controlling oxygen and sulfur content throughout the melting process. Furthermore, a complete technical solution encompassing raw material selection, charging methods, parameter optimization at each melting stage, and improvements to the zirconium addition process has not been developed. This results in zirconium content failing to meet alloy design requirements, limiting the application effectiveness of zirconium-containing alloys. Therefore, a vacuum induction melting process capable of achieving accurate and stable control of zirconium content and significantly improving zirconium yield is urgently needed. Summary of the Invention

[0004] The purpose of this invention is to provide a vacuum induction melting process for zirconium-containing alloys. This process can solve the technical problem of accurate and stable control of zirconium content during the vacuum induction melting of zirconium-containing alloys, thereby improving the zirconium yield.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: According to a first aspect of the present invention, a method for vacuum induction melting of a zirconium-containing alloy is provided, wherein the zirconium-containing alloy comprises, by mass percentage: C: 0.26%~0.30%, Si: 0.40%~0.50%, Mn: 0.20%~0.30%, V: 1.30%~1.50%, Zr: 0.20%~0.35%, Ni: 37.00%~38.00%, with the balance being Fe. The method comprises the following steps: Raw material selection: C source, Si source, Mn source, V source, Zr source, Ni source, and Fe source are carefully selected. According to the composition control requirements of the zirconium-containing alloy, the dosage of each raw material is formulated to control the total oxygen content in the raw materials to be no higher than 0.018% and the total sulfur content to be no higher than 0.0010%. Charging: Ni source, C source, V source and Fe source are charged into the vacuum induction furnace; Melting: After the material is loaded, vacuuming is started. When the leakage rate of the vacuum induction furnace is controlled to be ≤0.6Pa / min and the vacuum degree is ≤10Pa, power is started. After the material is melted and cleared, the temperature is raised to 1570℃~1600℃ and degassing is carried out by industrial frequency stirring. Refining: Control the vacuum degree to 0.3~0.8Pa, control the refining temperature to 1480℃~1530℃, and the refining time to 90~150min; Alloying: Add Zr source, Si source, Mn source and deoxidizer to the molten steel, control the temperature of the molten steel at 1380℃~1430℃, and carry out alloying under Ar purging conditions of 22000~28000Pa; Tapping: The tapping temperature is controlled at 1580℃~1600℃.

[0006] As a further implementation, in the raw material selection step, industrial high-purity graphite, metallic silicon, electrolytic manganese, ferrovanadium, metallic zirconium, industrial high-purity nickel plate, and industrial pure iron are selected as C source, Si source, Mn source, V source, Zr source, Ni source, and Fe source, respectively. The industrial high-purity graphite is graphite with a carbon content ≥99.9% and an ash content ≤100ppm, the industrial high-purity nickel plate is nickel plate with a nickel content ≥99.9%, and the industrial pure iron is iron material with an iron content ≥99.6%.

[0007] As a further embodiment, in the raw material selection step, the amount of zirconium metal is added at 0.30% to 0.55%.

[0008] As a further embodiment, in the raw material selection step, all raw materials are free of surface oxides, oil stains and impurities before use.

[0009] As a further implementation method, in the loading step, a batch loading method is adopted. In the first batch of loading, all the industrial high-purity nickel plates, industrial high-purity graphite, ferrovanadium and some industrial pure iron are added in sequence. In the second batch of loading, the remaining industrial pure iron is added.

[0010] As a further implementation, in the melting step, the power is gradually increased to 1400KW in the early stage of the melting of the first batch of materials. After ensuring the stable formation of the molten pool, the power supply is reduced to 900~1100KW for melting. The total melting time is controlled at 5h~8h. After the first batch of materials and the second batch of materials are melted and cleared, the temperature is raised to 1570℃~1600℃ and degassing is carried out by stirring at industrial frequency for 30~40min.

[0011] As a further embodiment, the refining step involves controlling the O content in the molten steel to ≤0.0012% and the S content to ≤0.0008% before proceeding to the alloying step.

[0012] As a further embodiment, in the alloying step, metallic silicon is first added to the molten steel and stirred for 25-35 minutes; then electrolytic manganese is added and stirred for 30-40 minutes; then 0.0030%-0.0060% of Ni-Mg alloy is added as a deoxidizer and stirred for 15-25 minutes; finally, metallic zirconium is added and stirred at industrial frequency for 5-10 minutes.

[0013] As a further embodiment, in the alloying step, the metallic zirconium is added in the form of metallic zirconium encapsulated in a slab of the steel grade.

[0014] According to a second aspect of the present invention, a zirconium-containing alloy prepared by the above method is provided.

[0015] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art: The present invention reduces the pressure of deoxidation and desulfurization during vacuum melting by strictly controlling the oxygen and sulfur content of the raw materials fed into the furnace. Through process optimization of charging, melting, and refining, it ensures that the molten steel entering the alloying stage has good conditions of low oxygen and low sulfur, which lays the foundation for accurate and stable control of zirconium content. Alloying further reduces the oxygen and sulfur content in the molten steel when adding zirconium by precisely controlling the temperature of the molten steel and the Ar purging intensity. At the same time, it optimizes the addition temperature, addition method and stirring process of zirconium, effectively reducing the oxidation loss and inclusion formation of zirconium. Finally, it achieves accurate and stable control of zirconium content in vacuum induction melting of zirconium-containing alloys, with the zirconium yield remaining stable at 86.3%~93.5%, significantly improving the product quality and performance stability of zirconium-containing alloys. Attached Figure Description

[0016] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0017] Figure 1 A flowchart of the vacuum induction melting method for zirconium-containing alloys provided by the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0019] Specific embodiments of the invention are disclosed herein as needed; however, it should be understood that the embodiments disclosed herein are merely examples of the invention that may be implemented in various alternative forms. In the following description, various operating parameters and components are described in several contemplated embodiments. These specific parameters and components are provided as examples only and are not intended to be limiting.

[0020] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0021] The first aspect of the present invention provides a vacuum induction melting method for a zirconium-containing alloy, wherein the zirconium-containing alloy comprises the following components by mass percentage: C: 0.26%~0.30%, Si: 0.40%~0.50%, Mn: 0.20%~0.30%, V: 1.30%~1.50%, Zr: 0.20%~0.35%, Ni: 37.00%~38.00%, with the balance being Fe.

[0022] like Figure 1 As shown, the method includes the following steps: S1 Raw Material Selection: Carefully selected C, Si, Mn, V, Zr, Ni, and Fe sources are used. Based on the composition control requirements of zirconium-containing alloys, the dosage of each raw material is formulated to control the total oxygen content in the raw materials to be no higher than 0.018% and the total sulfur content to be no higher than 0.0010%. S2 charging: Ni source, C source, V source and Fe source are charged into the vacuum induction furnace; S3 Melting: After the material is loaded, vacuuming begins. The leakage rate of the vacuum induction furnace is controlled to be ≤0.6Pa / min, and the vacuum degree is ≤10Pa. Power is then supplied. After the material is melted and cleared, the temperature is raised to 1570℃~1600℃, and degassing is performed by stirring at industrial frequency. S4 refining: control vacuum degree 0.3~0.8Pa, control refining temperature 1480℃~1530℃, refining time 90~150min; S5 alloying: Add Zr source, Si source, Mn source and deoxidizer to the molten steel, control the temperature of the molten steel at 1380℃~1430℃, and carry out alloying under Ar charging conditions of 22000~28000Pa. S6 tapping: The tapping temperature is controlled at 1580℃~1600℃.

[0023] In the S1 raw material selection step, the amount of oxygen and sulfur introduced into the raw materials is strictly controlled to reduce the pressure of deoxidation and desulfurization during vacuum melting from the source.

[0024] In some embodiments, industrial high-purity graphite, metallic silicon, electrolytic manganese, ferrovanadium, metallic zirconium, industrial high-purity nickel plate, and industrial pure iron are selected as raw materials. Specifically, industrial high-purity graphite, metallic silicon, electrolytic manganese, ferrovanadium, metallic zirconium, industrial high-purity nickel plate, and industrial pure iron are selected as C source, Si source, Mn source, V source, Zr source, Ni source, and Fe source, respectively. The industrial high-purity graphite is graphite with a carbon content ≥99.9% and an ash content ≤100ppm; the industrial high-purity nickel plate is nickel plate with a nickel content ≥99.9%; and the industrial pure iron is iron material with an iron content ≥99.6%. In some embodiments, the Zr source is added at a rate of 0.30% to 0.55%, i.e., zirconium element is added at a rate of 0.3% to 0.55%, to compensate for the burn-off and oxidation loss of zirconium during the smelting process, which leads to a weakened strengthening effect. The amount of Zr source used can typically, but not limited to, be set to 0.30%, 0.35%, 0.40%, 0.45%, 0.50%, or 0.55%.

[0025] In some embodiments, all raw materials must be thoroughly cleaned of surface oxides, oil stains and impurities before use to reduce the deoxidation and desulfurization pressure during the smelting process, reduce the reaction of zirconium with oxygen and sulfur to form inclusions, thereby ensuring the zirconium yield.

[0026] In some embodiments, a batch charging method is adopted in the S2 charging step to optimize the molten pool reaction conditions and reduce the ineffective consumption of zirconium. The first batch of charging consists of all the industrial high-purity nickel plates, industrial high-purity graphite, ferrovanadium, and a portion of industrial pure iron. The second batch of charging adds the remaining industrial pure iron. Adding all the industrial high-purity graphite in the first batch ensures a low carbon concentration in the initial stage of the molten pool, which is beneficial for promoting the CO reaction during melting, improving degassing and deoxidation during melting, and creating a low-oxygen environment for the subsequent addition of zirconium.

[0027] In some embodiments, the first batch of charge contains 1 / 3 industrial pure iron, and the second batch of charge contains the remaining 2 / 3 industrial pure iron.

[0028] In the S3 melting step, the leakage rate of the vacuum induction furnace is strictly controlled to be ≤0.6Pa / min to avoid oxygenation of the molten steel due to leakage during the smelting process.

[0029] In some embodiments, during the melting step, the power is gradually increased to 1400KW in the early stage of the first batch of charging to ensure the stable formation of the molten pool. After this, the power is reduced to 900~1100KW for material melting, and the total melting time is controlled to be 5h~8h. After the first and second batches of charging are melted and cleared, the temperature is raised to 1570℃~1600℃, and degassing is performed by stirring at industrial frequency for 30~40min. The material melting power can typically, but is not limited to, be set to 900KW, 950KW, 1000KW, 1050KW, or 1100KW; the total melting time can typically, but is not limited to, be set to 5h, 6h, 7h, or 8h; the temperature rise after clearing the molten pool can typically, but is not limited to, be set to 1570℃, 1580℃, 1590℃, or 1600℃; and the stirring time can typically, but is not limited to, be set to 30min, 35min, or 40min.

[0030] In some embodiments, after charging is completed, the vacuum system is activated to evacuate the furnace, strictly controlling the leakage rate of the vacuum induction furnace to ≤0.6Pa / min to avoid oxygenation of the molten steel due to leakage during smelting. Power is supplied when the vacuum degree is ≤10Pa during the melting period. The power is gradually increased to 1400KW in the early stage of the first batch of material melting. After ensuring the stable formation of the molten pool, the power supply is reduced to 900~1100KW for melting. The total melting period is controlled at 5h~8h. After the first and second batches of material are melted and cleared, the temperature is raised to 1570℃~1600℃, and degassing is performed by stirring at industrial frequency for 30~40min. After the last batch of material is melted and cleared and stirred, the refining period begins. Extending the melting time and performing industrial frequency stirring at a specific temperature can provide good thermodynamic and kinetic conditions for the CO reaction, effectively removing gas and some oxygen from the molten pool, laying the foundation for the stable existence of zirconium. In the S4 refining step, a low-temperature refining deoxidation process is adopted to precisely control the vacuum degree, temperature and time during the refining period. This ensures that the CO reaction continues and reduces the oxygen content in the molten steel to a low level. It also avoids oxygen supply to the crucible due to excessive temperature or improper vacuum, preventing the oxygen content in the molten steel from rebounding and further reducing the risk of zirconium oxidation.

[0031] In the refining step, the vacuum level can typically, but not limited to, be set to 0.3 Pa, 0.4 Pa, 0.5 Pa, 0.6 Pa, 0.7 Pa, or 0.8 Pa; the refining temperature can typically, but not limited to, be set to 1480°C, 1490°C, 1500°C, 1510°C, 1520°C, or 1530°C; and the refining time can typically, but not limited to, be set to 90 min, 100 min, 110 min, 120 min, 130 min, 140 min, or 150 min.

[0032] In some embodiments, after controlling the O content in the molten steel to ≤0.0012% and the S content to ≤0.0008% in the refining step, the steel proceeds to the alloying step.

[0033] In the S5 alloying step, using a low temperature and an Ar charging pressure higher than the saturated vapor pressure of electrolytic manganese, metallic silicon, and other raw materials ensures uniform dissolution of the raw materials while avoiding an increase in oxygen content due to the failure of carbon deoxidation under vacuum conditions. The molten steel temperature can typically, but is not limited to, 1380℃, 1390℃, 1400℃, 1410℃, 1420℃, and 1430℃; the Ar charging pressure can typically, but is not limited to, 22000Pa, 23000Pa, 24000Pa, 25000Pa, 26000Pa, 27000Pa, and 28000Pa.

[0034] In some embodiments, during the S5 alloying step, metallic silicon is first added to the molten steel and stirred for 25-35 minutes; then electrolytic manganese is added and stirred for 30-40 minutes; next, 0.0030%-0.0060% of Ni-Mg alloy is added as a deoxidizer and stirred for 15-25 minutes; finally, metallic zirconium is added and stirred at industrial frequency for 5-10 minutes. During the deoxidation and desulfurization process, Mg combines with O and S elements in the molten steel to form compounds such as MgO and MgS. These compounds have low density and float, and are removed in the final steel casting process.

[0035] In some embodiments, during the S5 alloying step, metallic zirconium is added in the form of metallic zirconium encapsulated in a slab of the steel grade.

[0036] In some embodiments, after refining, the alloying stage begins, with the molten steel temperature controlled at 1380℃~1430℃. This stage is carried out under Ar purging conditions of 22000~28000Pa. First, metallic silicon is added to the molten steel and stirred for 25~35 minutes to ensure uniform dissolution. Next, electrolytic manganese is added and stirred for 30~40 minutes for thorough deoxidation and desulfurization. Then, 0.0030%~0.0060% of Ni-Mg alloy is added and stirred for 15~25 minutes to further remove residual O and S from the molten steel. Finally, the molten steel temperature is controlled at 1380℃, and 0.3%~0.55% metallic zirconium wrapped in slabs of this steel grade is added. After stirring at industrial frequency for 8 minutes, the temperature is raised to 1580℃~1600℃ using a 1400KW power supply before tapping. Thorough stirring ensures uniform dissolution of raw materials while fully deoxidizing and desulfurizing, reducing the reaction of zirconium with oxygen and sulfur. The addition of metallic zirconium by wrapping the slab with this steel grade, combined with industrial frequency stirring, increases the density of zirconium, causing it to sink rapidly in the molten steel. On the other hand, the wrapped slab melts first, preventing zirconium from immediately contacting the molten steel and causing oxidation and burn-off. At the same time, industrial frequency stirring enables zirconium to be quickly entrained into the molten steel and dissolved uniformly, significantly improving the zirconium yield.

[0037] In the S6 tapping step, the tapping temperature can typically, but not limitedly, be set to 1580°C, 1590°C, or 1600°C.

[0038] In some embodiments, during the S6 tapping step, the ingot mold must be scalded with molten steel to ensure it is clean and free of impurities.

[0039] In some embodiments, a Φ30mm sprue is used to control the casting speed, ensuring that each steel ingot is cast in 1-2 minutes. Stable casting temperature and speed can avoid additional zirconium loss due to temperature fluctuations or secondary oxidation during casting, ensuring a stable zirconium yield of 86.3%-93.5%. Furthermore, the casting temperature of the alloy must not be too low, and the casting speed must not be too slow, to prevent the alloy from solidifying too quickly, leading to solidification defects such as porosity and shrinkage cavities.

[0040] A second aspect of the present invention provides a zirconium-containing alloy prepared by the above method.

[0041] This invention reduces the pressure of deoxidation and desulfurization during vacuum melting by strictly controlling the oxygen and sulfur content of the raw materials fed into the furnace. Through process optimization during charging, melting, and refining, it ensures that the molten steel entering the alloying stage has favorable conditions of low oxygen and low sulfur, laying the foundation for accurate and stable control of zirconium content. During the alloying stage, by precisely controlling the temperature of the molten steel, the Ar charging intensity, the amount, order of addition, and stirring time of various raw materials and deoxidizers, the oxygen and sulfur content in the molten steel is further reduced when zirconium is added. At the same time, the addition temperature, addition method, and stirring process of zirconium are optimized, effectively reducing the oxidation loss and inclusion formation of zirconium. Ultimately, accurate and stable control of zirconium content is achieved in vacuum induction melting of zirconium-containing alloys, with the zirconium yield remaining stable at 86.3%~93.5%, significantly improving the product quality and performance stability of zirconium-containing alloys.

[0042] The present invention will be further explained and described below with reference to specific embodiments.

[0043] Example 1 This embodiment uses a 10-ton vacuum induction furnace to implement the vacuum induction melting process of zirconium-containing alloys, achieving accurate and stable control of zirconium content in vacuum induction melting of zirconium-containing alloys, while reducing the formation of large-sized carbides.

[0044] ① The standard chemical composition requirements for zirconium-containing alloys are: C: 0.26% (lower limit), Si: 0.4%~0.5%, Mn: 0.2%~0.3%, V: 1.3% (lower limit), Zr: 0.2%~0.35%, Ni: 37%~38%, with the balance being Fe.

[0045] ② Raw material selection: High-purity graphite, metallic silicon, electrolytic manganese, ferrovanadium, metallic zirconium, high-purity nickel plate and pure iron are carefully selected as raw materials. The amount of each element raw material is calculated and formulated according to the mass percentage to ensure that the total O content of the raw materials is 0.018% and the S content is 0.0010% according to the composition system. The metallic zirconium element of the alloy raw materials is added at 0.3%. All raw materials are thoroughly cleaned of surface oxides, oil stains and impurities.

[0046] ③ Charging: Charging is carried out in batches. In the first batch, all the high-purity nickel plates, all the high-purity graphite, all the ferrovanadium, and 1 / 3 of the pure iron are added in sequence. In the second batch, the remaining pure iron is added. Metallic zirconium, metallic silicon, electrolytic manganese, and Ni-Mg alloy are added during the alloying period.

[0047] ④ Melting period: After the material is loaded, start the vacuum system to draw a vacuum and control the leakage rate of the vacuum induction furnace to 0.6 Pa / min. When the vacuum degree reaches 10 Pa during the melting period, start power supply. In the early stage of the first batch of material melting, gradually increase the power to 1400 KW. After the molten pool is stably formed, reduce the power supply to 900 KW to melt the material. The total melting period is 8 hours. After the first and second batches of material are melted and cleared, raise the temperature to 1600℃ and use industrial frequency stirring for 30 minutes for degassing. After the last batch of material is melted and cleared and stirred, the refining period begins.

[0048] ⑤ Refining period: During the refining period, the vacuum degree is controlled at 0.3 Pa, and a low-temperature refining and deoxidation process is adopted. The refining temperature is controlled at 1530℃ and the refining time is 90 min. After the O content and S content in the molten steel are tested to be 0.0012% and 0.0008%, the alloying period begins.

[0049] ⑥ Alloying Period: After refining, the alloying period begins. The temperature of the molten steel is controlled at 1430℃. This stage is carried out under Ar purging at 22000Pa. First, metallic silicon is added to the molten steel and stirred for 25 minutes to ensure uniform dissolution. Next, electrolytic Mn is added and stirred for 30 minutes to carry out thorough deoxidation and desulfurization treatment. Then, 0.0060% Ni-Mg alloy is added and stirred for 15 minutes to further remove residual O and S from the molten steel. Finally, the temperature of the molten steel is controlled at 1380℃, and 0.3% metallic zirconium wrapped with slab of this steel grade is added. After stirring at industrial frequency for 8 minutes, the temperature is raised to 1600℃ using a 1400KW power supply before tapping the steel.

[0050] ⑦ Tillage: The ingot mold is scalded with molten steel to ensure it is clean and free of impurities. The tapping temperature is controlled at 1600℃, and a Φ30mm sprue is used to control the casting speed, ensuring that each ingot is cast in 2 minutes.

[0051] Gas and chemical composition analysis was performed on samples of ingots produced using this process. The ingots contained 0.0007% O, 0.0006% S, and 0.2589% zirconium, with a zirconium yield of 86.3%. There were no obvious porosity or shrinkage cavities inside the ingots, and the amount of large-sized carbides formed was significantly reduced, meeting the alloy performance requirements.

[0052] Example 2 This embodiment uses a 10-ton vacuum induction furnace to implement the vacuum induction melting process of zirconium-containing alloys, achieving accurate and stable control of zirconium content in vacuum induction melting of zirconium-containing alloys, while reducing the formation of large-sized carbides.

[0053] ① The standard chemical composition requirements for zirconium-containing alloys are: C: 0.26% (lower limit), Si: 0.4%~0.5%, Mn: 0.2%~0.3%, V: 1.3% (lower limit), Zr: 0.2%~0.35%, Ni: 37%~38%, with the balance being Fe.

[0054] ② Raw material selection: High-purity graphite, metallic silicon, electrolytic manganese, ferrovanadium, metallic zirconium, high-purity nickel plate and pure iron are carefully selected as raw materials. The amount of each element raw material is calculated and formulated according to the mass percentage to ensure that the total O content of the raw materials is 0.015% and the S content is 0.0009% according to the composition system. The metallic zirconium element of the alloy raw materials is added at 0.45%. All raw materials are thoroughly cleaned of surface oxides, oil stains and impurities.

[0055] ③ Charging: Charging is carried out in batches. In the first batch, all the high-purity nickel plates, all the high-purity graphite, all the ferrovanadium, and 1 / 3 of the pure iron are added in sequence. In the second batch, the remaining pure iron is added. Metallic zirconium, metallic silicon, electrolytic manganese, and Ni-Mg alloy are added during the alloying period.

[0056] ④ Melting period: After the material is loaded, start the vacuum system to draw a vacuum and control the leakage rate of the vacuum induction furnace to 0.4 Pa / min. When the vacuum degree reaches 8 Pa during the melting period, start power supply. In the early stage of the first batch of material melting, gradually increase the power to 1400 KW. After the molten pool is stably formed, reduce the power supply to 1000 KW to melt the material. The total melting period is 6.5 hours. After the first and second batches of material are melted and cleared, raise the temperature to 1580℃ and use industrial frequency stirring for 35 minutes for degassing. After the last batch of material is melted and cleared and stirred, the refining period begins.

[0057] ⑤ Refining period: During the refining period, the vacuum degree is controlled at 0.5Pa, and a low-temperature refining and deoxidation process is adopted. The refining temperature is controlled at 1500℃ and the refining time is 120min. After the O content and S content in the molten steel are tested to be 0.0009% and 0.0007%, the alloying period begins.

[0058] ⑥ Alloying Period: After refining, the alloying period begins. The temperature of the molten steel is controlled at 1400℃. This stage is carried out under Ar charging at 25000Pa. First, metallic silicon is added to the molten steel and stirred for 30 minutes to ensure uniform dissolution. Second, electrolytic Mn is added and stirred for 35 minutes to carry out thorough deoxidation and desulfurization treatment. Third, 0.0045% Ni-Mg alloy is added and stirred for 20 minutes to further remove residual O and S in the molten steel. Finally, the temperature of the molten steel is controlled at 1380℃, and 0.45% metallic zirconium wrapped with slab of this steel grade is added. After stirring at industrial frequency for 8 minutes, the temperature is raised to 1590℃ using a 1400KW power supply before tapping the steel.

[0059] ⑦ Tillage: The ingot mold is scalded with molten steel to ensure it is clean and free of impurities. The tapping temperature is controlled at 1590℃, and a Φ30mm sprue is used to control the casting speed, ensuring that each ingot is cast in 1.5 minutes.

[0060] Gas and chemical composition analysis was performed on samples of ingots produced using this process. The ingots contained 0.0005% O, 0.0005% S, and 0.41075% zirconium, with a zirconium yield of 91.28%. The ingots had a dense internal structure, no solidification defects such as porosity and shrinkage cavities, and very few large-sized carbides, resulting in excellent overall alloy performance.

[0061] Example 3 This embodiment uses a 10-ton vacuum induction furnace to implement the vacuum induction melting process of zirconium-containing alloys, achieving accurate and stable control of zirconium content in vacuum induction melting of zirconium-containing alloys, while reducing the formation of large-sized carbides.

[0062] ① The standard chemical composition requirements for zirconium-containing alloys are: C: 0.26% (lower limit), Si: 0.4%~0.5%, Mn: 0.2%~0.3%, V: 1.3% (lower limit), Zr: 0.2%~0.35%, Ni: 37%~38%, with the balance being Fe.

[0063] ② Raw material selection: High-purity graphite, metallic silicon, electrolytic manganese, ferrovanadium, metallic zirconium, high-purity nickel plate and pure iron are carefully selected as raw materials. The amount of each element raw material is calculated and formulated according to the mass percentage to ensure that the total O content of the raw materials is 0.012% and the S content is 0.0008% according to the composition system. The metallic zirconium element of the alloy raw materials is added at 0.55%. All raw materials are thoroughly cleaned of surface oxides, oil stains and impurities.

[0064] ③ Charging: Charging is carried out in batches. In the first batch, all the high-purity nickel plates, all the high-purity graphite, all the ferrovanadium, and 1 / 3 of the pure iron are added in sequence. In the second batch, the remaining pure iron is added. Metallic zirconium, metallic silicon, electrolytic manganese, and Ni-Mg alloy are added during the alloying period.

[0065] ④ Melting period: After the material is loaded, start the vacuum system to draw a vacuum and control the leakage rate of the vacuum induction furnace to 0.3 Pa / min. When the vacuum degree reaches 5 Pa during the melting period, start power supply. In the early stage of the first batch of material melting, gradually increase the power to 1400 KW. After the molten pool is stably formed, reduce the power supply to 1100 KW to melt the material. The total melting period is 5 hours. After the first and second batches of material are melted and cleared, raise the temperature to 1570℃ and use industrial frequency stirring for 40 minutes for degassing. After the last batch of material is melted and cleared and stirred, the refining period begins.

[0066] ⑤ Refining period: During the refining period, the vacuum degree is controlled at 0.8 Pa, and a low-temperature refining and deoxidation process is adopted. The refining temperature is controlled at 1480℃ and the refining time is 150 min. After the O content and S content in the molten steel are tested to be 0.0008% and 0.0006% respectively, the alloying period begins.

[0067] ⑥ Alloying Period: After refining, the alloying period begins. The temperature of the molten steel is controlled at 1380℃. This stage is carried out under Ar purging at 28000Pa. First, metallic silicon is added to the molten steel and stirred for 35 minutes to ensure uniform dissolution. Next, electrolytic Mn is added and stirred for 40 minutes to carry out thorough deoxidation and desulfurization treatment. Then, 0.0030% Ni-Mg alloy is added and stirred for 25 minutes to further remove residual O and S from the molten steel. Finally, the temperature of the molten steel is controlled at 1380℃, and 0.55% metallic zirconium wrapped with slab of this steel grade is added. After stirring at industrial frequency for 8 minutes, the temperature is raised to 1580℃ using a 1400KW power supply before tapping the steel.

[0068] ⑦ Tillage: The ingot mold is scalded with molten steel to ensure it is clean and free of impurities. The tapping temperature is controlled at 1580℃, and a Φ30mm sprue is used to control the casting speed, ensuring that each ingot is cast in 1 minute.

[0069] Gas and chemical composition analysis was performed on samples of ingots produced using this process. The ingots contained 0.0004% O, 0.0004% S, and 0.51425% zirconium, with a zirconium yield of 93.5%. The ingots exhibited good solidification quality, with no porosity or shrinkage cavities. Furthermore, due to the lower limit control of C and V, large-sized carbides were effectively suppressed, fully meeting the alloy design and application requirements.

[0070] Finally, it should be noted that the embodiments described above are only some, not all, of the embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A method for vacuum induction melting of zirconium-containing alloys, characterized in that, The zirconium-containing alloy comprises, by mass percentage: C: 0.26%~0.30%, Si: 0.40%~0.50%, Mn: 0.20%~0.30%, V: 1.30%~1.50%, Zr: 0.20%~0.35%, Ni: 37.00%~38.00%, with the balance being Fe. The method includes the following steps: Raw material selection: C source, Si source, Mn source, V source, Zr source, Ni source, and Fe source are carefully selected. According to the composition control requirements of the zirconium-containing alloy, the dosage of each raw material is formulated to control the total oxygen content in the raw materials to be no higher than 0.018% and the total sulfur content to be no higher than 0.0010%. Charging: Ni source, C source, V source and Fe source are charged into the vacuum induction furnace; Melting: After the material is loaded, vacuuming is started. When the leakage rate of the vacuum induction furnace is controlled to be ≤0.6Pa / min and the vacuum degree is ≤10Pa, power is started. After the material is melted and cleared, the temperature is raised to 1570℃~1600℃ and degassing is carried out by industrial frequency stirring. Refining: Control the vacuum degree to 0.3~0.8Pa, control the refining temperature to 1480℃~1530℃, and the refining time to 90~150min; Alloying: Add Zr source, Si source, Mn source and deoxidizer to the molten steel, control the temperature of the molten steel at 1380℃~1430℃, and carry out alloying under Ar purging conditions of 22000~28000Pa; Tapping: The tapping temperature is controlled at 1580℃~1600℃.

2. The vacuum induction melting method for zirconium-containing alloys according to claim 1, characterized in that, In the raw material selection step, industrial high-purity graphite, metallic silicon, electrolytic manganese, ferrovanadium, metallic zirconium, industrial high-purity nickel plate, and industrial pure iron are selected as C source, Si source, Mn source, V source, Zr source, Ni source, and Fe source, respectively. The industrial high-purity graphite is graphite with a carbon content ≥99.9% and an ash content ≤100ppm, the industrial high-purity nickel plate is nickel plate with a nickel content ≥99.9%, and the industrial pure iron is iron material with an iron content ≥99.6%.

3. The vacuum induction melting method for zirconium-containing alloys according to claim 2, characterized in that, In the raw material selection step, the amount of metallic zirconium is added at 0.30% to 0.55%.

4. The vacuum induction melting method for zirconium-containing alloys according to claim 2, characterized in that, In the raw material selection step, all raw materials are free of surface oxides, oil stains and impurities before use.

5. The vacuum induction melting method for zirconium-containing alloys according to claim 2, characterized in that, In the loading step, a batch loading method is adopted. In the first batch, all the industrial high-purity nickel plates, industrial high-purity graphite, ferrovanadium and some industrial pure iron are added in sequence. In the second batch, the remaining industrial pure iron is added.

6. The vacuum induction melting method for zirconium-containing alloys according to claim 5, characterized in that, In the melting step, the power is gradually increased to 1400KW in the early stage of the first batch of charging to ensure the stable formation of the molten pool. Then, the power supply is reduced to 900~1100KW for melting. The total melting time is controlled between 5h and 8h. After the first batch of charging and the second batch of charging are melted and cleared, the temperature is raised to 1570℃~1600℃ and degassing is carried out by stirring at industrial frequency for 30~40min.

7. The vacuum induction melting method for zirconium-containing alloys according to claim 1, characterized in that, In the refining step, the molten steel is controlled to have O ≤ 0.0012% and S ≤ 0.0008% before proceeding to the alloying step.

8. The vacuum induction melting method for zirconium-containing alloys according to claim 2, characterized in that, In the alloying step, firstly, metallic silicon is added to the molten steel and stirred for 25-35 minutes; then, electrolytic manganese is added and stirred for 30-40 minutes; then, 0.0030%-0.0060% of Ni-Mg alloy is added as a deoxidizer and stirred for 15-25 minutes; finally, metallic zirconium is added and stirred at industrial frequency for 5-10 minutes.

9. The vacuum induction melting method for zirconium-containing alloys according to claim 8, characterized in that, In the alloying step, the metallic zirconium is added in the form of metallic zirconium encapsulated in a slab of this steel grade.

10. A zirconium-containing alloy, characterized in that, It is prepared by any one of claims 1-9.

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