Method for controlling oxygen and nitrogen elements of low-carbon high-aluminum-titanium-content nickel-based superalloy cast ingot

Abstract

The invention belongs to the technical field of high-temperature alloy smelting, and particularly discloses a control method for oxygen and nitrogen elements of a low-carbon high-aluminum-titanium-content nickel-based high-temperature alloy ingot. In order to solve the technical problem that the oxygen and nitrogen content of a current low-carbon high-aluminum-titanium-content nickel base easily exceeds the standard, an oxidizing agent and an excessive carbon source are actively added in the vacuum induction melting process to enhance the carbon-oxygen reaction, the oxygen and nitrogen carrying-in amount of raw materials corresponding to the titanium element is reduced, a deoxidizing agent is adopted for further deep deoxidation before pouring, and the oxygen and nitrogen content is reduced. The purpose of reducing the content of oxygen and nitrogen in the alloy cast ingot is achieved by combining protective atmosphere electroslag remelting and vacuum self-consuming arc remelting.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature alloy smelting technology, specifically relating to a method for controlling oxygen and nitrogen elements in low-carbon, high-aluminum, and high-titanium content nickel-based high-temperature alloy ingots, and particularly to a method for removing oxygen and nitrogen elements in the triple smelting process of low-carbon, high-aluminum, and high-titanium content nickel-based high-temperature alloys. Background Technology

[0002] Nickel-based superalloys are currently the main structural materials for the hot sections of aero-engines. To meet the ever-increasing demands for reliability, lifespan, and thrust-to-weight ratio in aero-engines, superalloys with higher service temperatures and longer service lives are required. For wrought superalloys, the current temperature resistance requirement has reached 800℃. These superalloys, such as GH4065A, U720Li (GH4720Li), and GH4151, are characterized by high alloying degree, strict requirements for oxygen and nitrogen content, and low carbon content (typically, the target carbon value is ≤0.020 wt%, while most nickel-based wrought superalloys have a target carbon value >0.020 wt%). Carbon in superalloys typically combines with elements such as titanium and niobium to form carbides, which provide some strengthening effect. However, the influence of carbon on the mechanical properties of the alloy is complex.

[0003] Currently, wrought superalloys have insufficient carbon content, resulting in low degassing capacity and difficulty in effectively removing oxygen and nitrogen from the alloy. Low-carbon, high-aluminum, and high-titanium superalloys typically contain high levels of reactive elements such as aluminum, titanium, and niobium, making them highly susceptible to oxide inclusions. Improper processing can lead to excessive inclusion residues, deteriorating the metallurgical quality of the material. Therefore, controlling gaseous elements in such alloys is a major technical challenge.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and propose a method for controlling oxygen and nitrogen content in low-carbon, high-aluminum-titanium nickel-based superalloy ingots. This invention addresses the technical problem of excessive oxygen and nitrogen content in a certain type of low-carbon, high-aluminum-titanium nickel-based superalloy. It achieves the goal of reducing the oxygen and nitrogen content in such alloy ingots by actively adding oxidants and excess carbon sources to enhance the carbon-oxygen reaction during vacuum induction melting, reducing the oxygen and nitrogen carried over by the raw materials corresponding to the alloy elements, further deoxidizing with deoxidizers before casting, and combining protective atmosphere electroslag remelting and vacuum consumable arc remelting.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a method for controlling oxygen and nitrogen elements in low-carbon, high-aluminum, and high-titanium content nickel-based superalloy ingots, comprising the following steps: Step 1: Clean the vacuum induction melting crucible with nickel, controlling the content of aluminum and titanium in the chemical composition of the ingot to be ≤0.2 wt%. Step 2: Prepare the raw materials according to the chemical composition range of the finished high-temperature alloy ingot. First, add the bottom raw materials and perform vacuum induction melting. After melting to the full melt state, fill the melting furnace with argon gas to the set pressure. Then add the oxidant and stir. Next, add the graphite block and stir. Then, evacuate to the set pressure and finally refine. Step 3: Add raw materials corresponding to certain alloying elements to the refined alloy liquid A so that the chemical composition range of the alloy liquid A meets the chemical composition range of the finished high-temperature alloy ingot. Step 4: Adjust the temperature of the alloy liquid A, add deoxidizer and stir, then let it stand, and then cast it into an ingot; Step 5: The ingot from Step 6 is annealed, ground, the riser is sawn off, electroslag remelted in a protective atmosphere, annealed, sawed off, peeled off, and vacuum arc consumable remelted to obtain the finished high-temperature alloy ingot.

[0007] Optionally, in step 2, the finished high-temperature alloy ingot includes U720Li and GH4065A alloy ingots.

[0008] Furthermore, in step 2, the base material includes raw materials corresponding to elements other than carbon, aluminum, titanium, niobium, boron, zirconium, manganese, and silicon; Furthermore, in step 2, after the bottom material is melted to a fully molten state, an alloy liquid B with a temperature of 1440~1500℃ is obtained, and the vacuum degree of the melting furnace chamber during the melting process is ≤1 hPa; The carbon content in alloy liquid B is controlled to be ≤0.008 wt%, and the contents of each element, such as aluminum, titanium, boron, zirconium, manganese, and silicon, are all ≤0.01 wt%.

[0009] Furthermore, in step 2, argon is introduced into the melting furnace chamber to a pressure of 90-500 hPa; Optionally, in step 2, argon is introduced into the melting furnace chamber to a pressure of 90, 100, 150, 200, 300, 400 or 480 hPa; Add an oxidant with a mass fraction of 0.001~0.03 wt% to alloy liquid B, stir for 2~20 min to obtain alloy liquid C; Optionally, an oxidant with a mass fraction of 0.001, 0.003, 0.004, 0.008, 0.01 or 0.015 wt% is added to the alloy liquid B, and the mixture is stirred for 2, 4, 6, 8, 10, 12, 15 or 18 min. Add graphite blocks to the alloy liquid C, control the carbon element mass fraction in the alloy liquid C to be 0.01~0.03wt%, stir for 3~20 min and then evacuate to a vacuum degree ≤1 hPa.

[0010] Furthermore, in step 2, during the refining process, the vacuum degree in the smelting furnace is ≤0.1 hPa, the refining temperature is 1500~1560℃, the time is 20~120min, and the refining process is stirred throughout.

[0011] Optionally, the refining temperature is 1500, 1520 or 1550°C, and the time is 20, 40, 50, 80 or 110 min.

[0012] Further, in step 2, the oxidant is a mixture of iron oxide and nickel oxide, wherein the iron oxide content is ≥20 wt%.

[0013] Furthermore, in step 3, the alloying elements include aluminum, titanium, and / or niobium. The raw material for aluminum is aluminum ingot, with an aluminum content ≥99.7%, an oxygen content ≤0.02%, and a nitrogen content ≤0.05%. The raw material for titanium is pure titanium ingot produced by vacuum arc melting, with a titanium content ≥99.7%, oxygen content ≤0.050%, and nitrogen content ≤0.010%. The raw materials for niobium are pure niobium blocks or nickel-niobium master alloys, with an oxygen content of ≤0.05% and a nitrogen content of ≤0.010%.

[0014] Further, in step 4, the temperature of the alloy liquid A is adjusted to 1430~1520℃, and then a deoxidizer with a mass fraction of 0.002~0.040 wt% is added to the alloy liquid A, stirred for 3~20 min, and allowed to stand for 3~10 min.

[0015] Optionally, in step 4, the temperature of the alloy liquid A is adjusted to 1430, 1450 or 1500°C, and then a deoxidizer with a mass fraction of 0.003, 0.010, 0.030 or 0.040 wt% is added to the alloy liquid A, stirred for 20 min, and allowed to stand for 3 min.

[0016] Furthermore, in step 4, during the casting process, the ratio of the weight of the molten metal in the riser to the total weight of the ingot is 0.03 to 0.1.

[0017] Furthermore, in step 4, the deoxidizer is a magnesium-cerium alloy, and the cerium content in the magnesium-cerium alloy is 15~30wt%.

[0018] Furthermore, in step 5, during vacuum arc self-consumption remelting, the vacuum level is set to ≤0.5 Pa and the leakage rate to ≤0.5 Pa / min.

[0019] Compared with the prior art, the present invention has the following beneficial effects: The control method proposed in this invention, during the vacuum induction melting stage, creates conditions to increase the intensity of the carbon-oxygen reaction by adding an appropriate amount of oxidant and excess carbon under relatively low vacuum. Refining under high temperature and high vacuum promotes heat and mass transfer, accelerates the rise of CO bubbles (reaction product), and simultaneously promotes the removal of N elements by the bubbles, achieving efficient removal of oxygen and nitrogen. Secondly, the quality and timing of the subsequent addition of aluminum, titanium, and niobium elements are controlled to further reduce the introduction of oxygen and nitrogen. In the final casting stage, a deoxidizer is added for further deep deoxidation, and vacuum casting with added insulating risers ensures sufficient feeding of the ingot, while gaseous elements are discharged to the riser position, achieving a low overall gas content in the ingot. By reducing oxygen and nitrogen content and combining this with the timing of aluminum, titanium, and niobium element addition, the formation of oxide or nitride inclusions can be significantly reduced, improving the metallurgical quality of the material. This, combined with the subsequent protective atmosphere electroslag remelting + vacuum arc consumable remelting process, produces high-quality ingots with low oxygen and nitrogen content.

[0020] This method can reduce the oxygen and nitrogen content in finished alloy ingots, producing high-quality, low-carbon, high-aluminum-titanium nickel-based high-temperature alloy ingots. However, conventional methods often result in unstable metallurgical quality in these ingots due to the low carbon content of the alloys, low carbon concentration in the molten alloy during vacuum induction melting, weak carbon-oxygen reaction kinetics, poor removal of gaseous elements, and high aluminum-titanium content, which easily introduces more oxides or nitrides. Attached Figure Description

[0021] The accompanying drawings are incorporated in and form part of this specification, and together with the description serve to explain the principles of the invention.

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a flowchart of the control method of the present invention; Figure 2 This is a photograph of the carbonitride at position R / 2 of the forged alloy bar in Embodiment 2 of the present invention; Figure 3 Photograph of carbonitrides at position R / 2 of the forged alloy bar in Comparative Example 2 of this invention. Detailed Implementation

[0024] Exemplary embodiments will now be described in detail. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples consistent with some aspects of the invention as detailed in the appended claims.

[0025] Please see Figure 1 This invention provides a method for controlling oxygen and nitrogen elements in low-carbon, high-aluminum, titanium-content nickel-based superalloy ingots, comprising the following steps: Step 1: Clean the vacuum induction melting crucible with nickel, controlling the content of aluminum and titanium in the chemical composition of the ingot to be ≤0.2 wt%. Step 2: Prepare the raw materials according to the chemical composition range of the finished high-temperature alloy ingot. First, add the bottom raw materials and perform vacuum induction melting. After melting to the full melt state, fill the melting furnace with argon gas to the set pressure. Then add the oxidant and stir. Next, add the graphite block and stir. Then, evacuate to the set pressure and finally refine. Step 3: Add raw materials corresponding to certain alloying elements to the refined alloy liquid A so that the chemical composition range of the alloy liquid A meets the chemical composition range of the finished high-temperature alloy ingot. Step 4: Adjust the temperature of the alloy liquid A, add deoxidizer and stir, then let it stand, and then cast it into an ingot; Step 5: The ingot from Step 6 is annealed, ground, the riser is sawn off, electroslag remelted in a protective atmosphere, annealed, sawed off, peeled off, and vacuum arc consumable remelted to obtain the finished high-temperature alloy ingot.

[0026] Optionally, in step 2, the finished high-temperature alloy ingot includes U720Li and GH4065A alloy ingots.

[0027] Furthermore, in step 2, the base material includes raw materials corresponding to elements other than carbon, aluminum, titanium, niobium, boron, zirconium, manganese, and silicon; Furthermore, in step 2, after the bottom material is melted to a fully molten state, an alloy liquid B with a temperature of 1440~1500℃ is obtained, and the vacuum degree of the melting furnace chamber during the melting process is ≤1 hPa; The carbon content in alloy liquid B is controlled to be ≤0.008 wt%, and the contents of each element, such as aluminum, titanium, boron, zirconium, manganese, and silicon, are all ≤0.01 wt%.

[0028] Furthermore, in step 2, argon is introduced into the melting furnace chamber to a pressure of 90-500 hPa; Add an oxidant with a mass fraction of 0.001~0.03 wt% to alloy liquid B, stir for 2~20 min to obtain alloy liquid C; Add graphite blocks to the alloy liquid C, control the carbon element mass fraction in the alloy liquid C to be 0.01~0.03wt%, stir for 3~20 min and then evacuate to a vacuum degree ≤1 hPa.

[0029] Furthermore, in step 2, during the refining process, the vacuum degree in the smelting furnace is ≤0.1 hPa, the refining temperature is 1500~1560℃, the time is 20~120min, and the refining process is stirred throughout.

[0030] Further, in step 2, the oxidant is a mixture of iron oxide and nickel oxide, wherein the iron oxide content is ≥20 wt%.

[0031] Furthermore, in step 3, the alloying elements include aluminum, titanium, and / or niobium. The raw material for aluminum is aluminum ingot, with an aluminum content ≥99.7%, an oxygen content ≤0.02%, and a nitrogen content ≤0.05%. The raw material for titanium is pure titanium ingot produced by vacuum arc melting, with a titanium content ≥99.7%, oxygen content ≤0.050%, and nitrogen content ≤0.010%. The raw materials for niobium are pure niobium blocks or nickel-niobium master alloys, with an oxygen content of ≤0.05% and a nitrogen content of ≤0.010%.

[0032] Further, in step 4, the temperature of the alloy liquid A is adjusted to 1430~1520℃, and then a deoxidizer with a mass fraction of 0.002~0.040 wt% is added to the alloy liquid A, stirred for 3~20 min, and allowed to stand for 3~10 min.

[0033] Furthermore, in step 4, during the casting process, the vacuum degree is ≤0.5 hPa, an insulating riser is used, and the ratio of the weight of the molten metal in the riser to the total weight of the ingot is 0.03~0.1.

[0034] Furthermore, in step 4, the deoxidizer is a magnesium-cerium alloy, and the cerium content in the magnesium-cerium alloy is 15~30wt%.

[0035] Furthermore, in step 5, during vacuum arc self-consumption remelting, the vacuum level is set to ≤0.5 Pa and the leakage rate to ≤0.5 Pa / min.

[0036] To demonstrate the effectiveness of the present invention, the present invention will be further described in detail below with reference to specific embodiments and comparative examples.

[0037] Example 1 (Preparation of U720Li alloy ingots using the oxygen and nitrogen element control method of the present invention) Includes the following steps: Step 1: Clean the vacuum induction melting crucible with nickel, controlling the content of aluminum and titanium in the chemical composition of the ingot to be ≤0.2 wt%. Step 2: The nominal feed amount is 8 tons, and the feed is prepared according to the chemical composition range of U720Li alloy ingot (see Table 1); First, the base material is added and vacuum induction melting is carried out. After melting to the fully molten state, alloy liquid B with a temperature of 1480~1500℃ is obtained, and the vacuum degree of the melting furnace is ≤1 hPa.

[0038] The base materials correspond to the elements of nickel (Ni), cobalt (Co), chromium (Cr), molybdenum (Mo), and tungsten (W). The specific materials selected are nickel plates, cobalt plates, high-purity chromium, molybdenum bars, and tungsten bars, excluding the materials corresponding to the elements of carbon (C), aluminum (Al), titanium (Ti), boron (B), and zirconium (Zr). The carbon content in alloy liquid B is controlled to be ≤0.006 wt%, and the content of each element, such as aluminum, titanium, boron, zirconium, manganese, and silicon, is controlled to be ≤0.01 wt%.

[0039] Step 3: Pour argon gas into the melting furnace chamber to 300±20 hPa, then add 0.015 wt% oxidant to the alloy liquid B and stir for 15 min to obtain alloy liquid C; The oxidant is a mixture of iron oxide and nickel oxide, with an iron oxide content of 50-80 wt%. Add graphite blocks to the alloy liquid C, control the carbon element mass fraction in the alloy liquid C to be 0.024 wt%, and stir for 10±5 min until there is no obvious bubbling on the liquid surface. After stirring, evacuate to a vacuum degree ≤0.5 hPa.

[0040] Step 4: Refine the alloy liquid C at high temperature to obtain alloy liquid A; The refining temperature is 1540℃, the vacuum degree is ≤0.1 hPa, and the refining stage is stirred throughout for 45 minutes. Step 5: Add aluminum, titanium, boron and zirconium alloying elements to alloy liquid A and adjust the chemical composition of alloy liquid A to meet the chemical composition range of each element in Table 1. Among them, aluminum ingots are selected as raw materials for aluminum, with an aluminum content ≥99.7%, an oxygen content ≤0.02%, and a nitrogen content ≤0.05%; pure titanium blocks produced by vacuum arc self-consumable melting are selected as raw materials for titanium, with a titanium content ≥99.7%, an oxygen content ≤0.05%, and a nitrogen content ≤0.01%; nickel-boron alloy is selected as raw material for boron, and sponge zirconium is selected as raw material for zirconium. Step 6: Adjust the temperature of alloy liquid A to 1440~1480℃, then add 0.013 wt% deoxidizer to alloy liquid A, stir for 10±1 min, let stand for 5±1 min, and then cast into an ingot. During the casting stage, the vacuum degree is ≤0.5 hPa, and an insulating riser is used to ensure that the ratio of the weight of the molten metal in the riser to the total weight of the cast ingot is 0.03~0.06; the nominal size of the ingot mold used for casting is Φ350 mm. Specifically, the deoxidizer is a magnesium-cerium alloy, wherein the cerium content in the magnesium-cerium alloy is 20 wt%. Step 7: The ingot obtained in Step 6 is annealed, ground, the riser is sawn off, electroslag remelted in a protective atmosphere, annealed, sawed, peeled off, and vacuum arc consumable remelted to obtain the finished ingot; Among them, the nominal size of the ingot for protective atmosphere electroslag melting is Φ450 mm; the vacuum degree of vacuum arc self-consuming melting is ≤0.5 Pa, the leakage rate is ≤0.5 Pa / min, and the nominal size of the ingot is Φ508 mm.

[0041] The elemental chemical composition of the U720Li alloy ingot prepared in this embodiment was tested, and the results are shown in Table 2.

[0042] Table 1 Composition requirements for U720Li alloy Table 2. Elemental chemical composition of the alloy ingot in Example 1 Comparative Example 1 U720Li alloy ingots were prepared according to the following method: Step 1: The nominal feed amount is 8 tons. The weight of each element is reserved according to the alloy to be fed into the furnace, and vacuum induction melting is carried out according to the U720Li alloy ratio requirements (the main component range of the alloy is shown in Table 1). First, a base material is added for vacuum induction melting. After melting to a fully molten state, an alloy liquid B with a temperature of 1480~1500℃ is obtained, and the vacuum degree of the melting furnace is ≤0.5 hPa.

[0043] The base materials correspond to nickel (Ni), cobalt (Co), chromium (Cr), molybdenum (Mo), tungsten (W), and carbon (C). The specific materials selected are nickel plates, cobalt plates, high-purity chromium, molybdenum bars, tungsten bars, and graphite blocks.

[0044] Step 2: Refine the alloy liquid B at high temperature to obtain alloy liquid A; The refining temperature is 1500℃, the vacuum degree is ≤0.2 hPa, and the refining stage is stirred throughout for 10 minutes.

[0045] Step 3: Add aluminum, titanium, boron and zirconium alloying elements to alloy liquid A to adjust the main chemical element composition of alloy liquid A to the target range.

[0046] The raw material for aluminum is aluminum briquettes, with an aluminum content ≥99.7%, an oxygen content ≤0.02%, and a nitrogen content of 0.05%; the raw material for titanium is MHT-95 sponge titanium (technical standard GB / T 2524), with an oxygen content ≤0.05 wt% and a nitrogen content ≤0.01 wt%. For boron, nickel-boron alloy is selected as the raw material; for zirconium, sponge zirconium is selected as the raw material. Step 4: Adjust the temperature of alloy liquid A to 1480~1500℃ and pour it into a cast ingot; during the pouring stage, argon is purged to 300±20hPa, and no heat-insulating riser is used. The nominal size of the ingot mold used for pouring is Φ430 mm. (5) The ingot obtained in step 4 is annealed, polished and vacuum arc self-consumable remelted to obtain the finished ingot; the vacuum degree of vacuum arc self-consumable remelting is ≤0.5 Pa, the leakage rate is ≤0.5 Pa / min, and the nominal specification of the ingot is Φ508 mm.

[0047] The statistics of the ingot smelting results in Comparative Example 1 are shown in Table 3. The contents of O and N both increased compared to Example 1.

[0048] Table 3. Elemental chemical composition of alloy ingots in Comparative Example 1 Example 2 (Preparation of GH4065A alloy ingot using the oxygen and nitrogen element control method of the present invention) Includes the following steps: Step 1: Clean the vacuum induction melting crucible with nickel to ensure that the aluminum and titanium content in the ingots is ≤0.2 wt%. Step 2: The nominal feed amount is 8 tons, and the feed is prepared according to the chemical composition range of GH4065A alloy ingot (see Table 4); First, the base material is added and vacuum induction melting is carried out. After melting to the fully molten state, alloy liquid B with a temperature of 1480~1500℃ is obtained, and the vacuum degree of the melting furnace is ≤1 hPa.

[0049] The base materials correspond to the elements of nickel (Ni), cobalt (Co), chromium (Cr), molybdenum (Mo), and tungsten (W). The specific materials selected are nickel plates, cobalt plates, high-purity chromium, molybdenum bars, and tungsten bars, excluding the materials corresponding to the elements of carbon (C), aluminum (Al), titanium (Ti), boron (B), and zirconium (Zr). The carbon content in alloy liquid B is controlled to be ≤0.006 wt%, and the content of each element (aluminum, titanium, boron, zirconium, manganese, and silicon) is ≤0.01 wt%.

[0050] Step 3: Pour argon gas into the melting furnace chamber to 250±20 hPa, then add 0.02 wt% oxidant to alloy liquid B and stir for 20 min to obtain alloy liquid C; The oxidant is a mixture of iron oxide and nickel oxide, with an iron oxide content of 70-90 wt%. Add graphite blocks to the alloy liquid C, control the carbon element mass fraction in the alloy liquid C to be 0.025 wt%, and stir for 10±2 min until there is no obvious bubbling on the liquid surface. After stirring, evacuate to a vacuum degree ≤0.4 hPa.

[0051] Step 4: Refine the alloy liquid C at high temperature to obtain alloy liquid A; The refining temperature is 1540℃, the vacuum degree is ≤0.1 hPa, and the refining stage is stirred throughout for 50 minutes. Step 5: Add aluminum, titanium, niobium, boron and zirconium alloying elements to the refined alloy liquid A to adjust the chemical composition range of the alloy liquid A to meet the chemical composition range of each element in Table 4. Among them, the raw material for aluminum is aluminum ingot with an aluminum content ≥99.7%, an oxygen content ≤0.02%, and a nitrogen content ≤0.05%; the raw material for titanium is pure titanium block produced by vacuum arc self-consumable melting with a titanium content ≥99.7%, an oxygen content ≤0.050%, and a nitrogen content ≤0.010%; the raw material for niobium is pure niobium block with an oxygen content ≤0.05% and a nitrogen content ≤0.010%; the raw material for boron is nickel-boron alloy; and the raw material for zirconium is sponge zirconium. Step 6: Adjust the temperature of alloy liquid A to 1480℃, then add 0.01wt% deoxidizer to alloy liquid A, stir for 10±1 min, let stand for 5±1 min, and then cast into an ingot. During the casting stage, the vacuum degree is ≤0.3 hPa, and an insulating riser is used to ensure that the ratio of the weight of the molten metal in the riser to the total weight of the cast ingot is 0.03~0.06; the nominal size of the ingot mold used for casting is Φ350 mm. Specifically, the deoxidizer is a magnesium-cerium alloy, wherein the cerium content in the magnesium-cerium alloy is 15 wt%. Step 7: The ingot obtained in Step 6 is annealed, ground, the riser is sawn off, electroslag remelted in a protective atmosphere, annealed, sawed, peeled off, and vacuum arc consumable remelted to obtain the finished ingot; Among them, the nominal size of the ingot for protective atmosphere electroslag melting is Φ450 mm; the vacuum degree of vacuum arc self-consuming melting is ≤0.3 Pa, the leakage rate is ≤0.3 Pa / min, and the nominal size of the ingot is Φ508 mm.

[0052] The statistics of the ingot-related smelting results in Example 2 are shown in Table 5. Figure 1 The image shows carbonitrides at the R / 2 position of the head of the alloy bar obtained by homogenization and forging of the ingot in Example 2. The carbonitrides are small in size, few in number, and diffusely distributed.

[0053] Table 4 Composition requirements for GH4065A alloy Table 5. Elemental chemical composition of the alloy ingot in Example 2 Comparative Example 2 GH4065A alloy ingots were prepared according to the following method: Step 1: The nominal feed amount is 8 tons. The weight of each element is reserved according to the alloy to be fed into the furnace, and vacuum induction melting is carried out according to the GH4065A alloy ratio requirements (the main component range of the alloy is shown in Table 4). First, add the base material and melt it to a fully molten state. The alloy liquid temperature is 1480~1500℃, and the vacuum degree of the melting furnace is ≤0.5 hPa. The base material corresponds to nickel (Ni), cobalt (Co), chromium (Cr), molybdenum (Mo), tungsten (W), and carbon (C).

[0054] Step 2: High-temperature refining is carried out at a temperature of 1500℃ and a vacuum degree of ≤0.2 hPa. The refining process is stirred throughout and takes 60 minutes.

[0055] Step 3: Add the corresponding raw materials for the alloying elements aluminum, titanium, niobium, boron, and zirconium to adjust the main chemical element composition of the alloy liquid to the target range. The raw material for aluminum is aluminum briquettes with an aluminum content ≥99.7%, oxygen content ≤0.02%, and nitrogen content ≤0.05%; the raw material for titanium is MHT-95 sponge titanium (GB / T 2524) with an oxygen content ≤0.05 wt% and a nitrogen content ≤0.01 wt%; the raw material for niobium is a nickel-niobium master alloy with a niobium content of 63.0%~70.0%, oxygen content ≤0.050%, and nitrogen content ≤0.030%.

[0056] Step 4: Adjust the temperature of the alloy liquid to 1470℃ and pour it into a cast ingot; during the pouring stage, argon is purged to 300±20 hPa, and no heat-insulating risers are used. The nominal size of the ingot mold used for pouring is Φ350 mm. Step 5: The ingot obtained in Step 4 is annealed, ground, the riser is sawn off, electroslag remelted in a protective atmosphere, annealed, sawed, peeled off, and vacuum arc consumable remelted to obtain the finished ingot; the nominal size of the electroslag remelted ingot is Φ450mm; the vacuum degree of the vacuum arc consumable remelting is ≤0.5 Pa, the leakage rate is ≤0.5 Pa / min, and the nominal size of the ingot is Φ508 mm.

[0057] The statistics of the ingot smelting results in Comparative Example 2 are shown in Table 6. The N content increased significantly compared with Example 1. Figure 2 The image shows carbonitrides at the R / 2 position of the head of the alloy bar obtained by homogenization and forging of the ingot in Comparative Example 2. The number and size of carbonitrides are increased compared to Example 2.

[0058] Table 6. Elemental chemical composition of alloy ingots in Comparative Example 2 Example 3 (Preparation of GH4065A alloy ingot using the oxygen and nitrogen element control method of the present invention) Includes the following steps: Step 1: Clean the vacuum induction melting crucible with nickel to ensure that the aluminum and titanium content in the ingots is ≤0.2 wt%. Step 2: The nominal feed amount is 8 tons, and the feed is prepared according to the chemical composition range of GH4065A alloy ingot (see Table 4); First, a base material is added for vacuum induction melting. After melting to a fully molten state, an alloy liquid B with a temperature of 1440~1460℃ is obtained, and the vacuum degree of the melting furnace chamber is ≤1 hPa.

[0059] The base materials correspond to the elements of nickel (Ni), cobalt (Co), chromium (Cr), molybdenum (Mo), and tungsten (W). The specific materials selected are nickel plates, cobalt plates, high-purity chromium, molybdenum bars, and tungsten bars, excluding the materials corresponding to the elements of carbon (C), aluminum (Al), titanium (Ti), boron (B), and zirconium (Zr). The carbon content in alloy liquid B is controlled to be ≤0.008 wt%, and the content of each element (aluminum, titanium, boron, zirconium, manganese, and silicon) is controlled to be ≤0.01 wt%.

[0060] Step 3: Pour argon gas into the melting furnace chamber to 200±20 hPa, then add 0.03 wt% oxidant to the alloy liquid B and stir for 15±5 min; The oxidant is a mixture of iron oxide and nickel oxide, with an iron oxide content of 70-90 wt%. Add graphite blocks to the alloy liquid C, control the carbon element mass fraction in the alloy liquid C to be 0.03 wt%, and stir for 5±2 min until there is no obvious bubbling on the liquid surface. After stirring, evacuate to a vacuum degree ≤1 hPa.

[0061] Step 4: Refine the alloy liquid C at high temperature to obtain alloy liquid A; The refining temperature is 1560℃, the vacuum degree is ≤0.1 hPa, and the refining stage is stirred throughout for 100 minutes. Step 5: Add aluminum, titanium, niobium, boron and zirconium alloying elements to the refined alloy liquid A to adjust the chemical composition range of the alloy liquid A to meet the chemical composition range of each element in Table 4. Among them, the raw material for aluminum is aluminum ingot with an aluminum content ≥99.7%, an oxygen content ≤0.02%, and a nitrogen content ≤0.05%; the raw material for titanium is pure titanium block produced by vacuum arc self-consumable melting with a titanium content ≥99.7%, an oxygen content ≤0.050%, and a nitrogen content ≤0.010%; the raw material for niobium is pure niobium block with an oxygen content ≤0.05% and a nitrogen content ≤0.010%; the raw material for boron is nickel-boron alloy; and the raw material for zirconium is sponge zirconium. Step 6: Adjust the temperature of alloy liquid A to 1520℃, then add 0.002wt% deoxidizer to alloy liquid A, stir for 5±1 min, let stand for 8±1 min, and then cast into an ingot. During the casting stage, the vacuum degree is ≤0.5 hPa, and an insulating riser is used so that the ratio of the weight of the molten metal in the riser to the total weight of the cast ingot is 0.08~0.1; the nominal size of the ingot mold used for casting is Φ350 mm. Specifically, the deoxidizer is a magnesium-cerium alloy, wherein the cerium content in the magnesium-cerium alloy is 30 wt%. Step 7: The ingot obtained in Step 6 is annealed, ground, the riser is sawn off, electroslag remelted in a protective atmosphere, annealed, sawed, peeled off, and vacuum arc consumable remelted to obtain the finished ingot; Among them, the nominal size of the ingot for electroslag remelting under protective atmosphere is Φ450 mm; the vacuum degree of vacuum arc self-consumable melting is ≤0.3 Pa, the leakage rate is ≤0.3 Pa / min, and the nominal size of the ingot is Φ508 mm. The statistics of the ingot-related melting results in Example 3 are shown in Table 7.

[0062] Table 7. Elemental chemical composition of the alloy ingot in Example 3 The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention.

[0063] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for controlling oxygen and nitrogen elements in low-carbon, high-aluminum, titanium-content nickel-based superalloy ingots, characterized in that, Includes the following steps: Step 1: Clean the vacuum induction melting crucible with nickel; Step 2: Prepare the raw materials according to the chemical composition range of the finished high-temperature alloy ingot. First, add the bottom raw materials and perform vacuum induction melting. After melting to the full melt state, fill the melting furnace with argon gas to the set pressure. Then add the oxidant and stir. Next, add the graphite block and stir. Then, evacuate to the set pressure and finally refine. Step 3: Add raw materials corresponding to certain alloying elements to the refined alloy liquid A so that the chemical composition range of the alloy liquid A meets the chemical composition range of the finished high-temperature alloy ingot. Step 4: Adjust the temperature of the alloy liquid A, add deoxidizer and stir, then let it stand, and then cast it into an ingot; Step 5: The ingot from Step 6 is annealed, ground, the riser is sawn off, electroslag remelted in a protective atmosphere, annealed, sawed off, peeled off, and vacuum arc consumable remelted to obtain the finished high-temperature alloy ingot.

2. The control method according to claim 1, characterized in that, In step 2, the base material includes raw materials corresponding to elements other than carbon, aluminum, titanium, niobium, boron, zirconium, manganese and silicon.

3. The control method according to claim 1, characterized in that, In step 2, the bottom material is melted to a fully molten state to obtain alloy liquid B with a temperature of 1440~1500℃, and the vacuum degree of the melting furnace chamber during the melting process is ≤1 hPa; The carbon content in alloy liquid B is controlled to be ≤0.008 wt%, and the contents of each element, such as aluminum, titanium, boron, zirconium, manganese, and silicon, are all ≤0.01 wt%.

4. The control method according to claim 1, characterized in that, In step 2, argon is introduced into the melting furnace chamber to a pressure of 90-500 hPa; Add an oxidant with a mass fraction of 0.001~0.03 wt% to alloy liquid B, stir for 2~20 min to obtain alloy liquid C; Add graphite blocks to the alloy liquid C, control the carbon element mass fraction in the alloy liquid C to be 0.01~0.03wt%, stir for 3~20min and then evacuate to a vacuum degree ≤1 hPa.

5. The control method according to claim 1, characterized in that, In step 2, during the refining process, the vacuum degree in the smelting furnace is ≤0.1 hPa, the refining temperature is 1500~1560℃, the time is 20~120 min, and the refining process is stirred throughout.

6. The control method according to claim 1 or 4, characterized in that, In step 2, the oxidant is a mixture of iron oxide and nickel oxide, wherein the iron oxide content is ≥20 wt%.

7. The control method according to claim 1, characterized in that, In step 3, the alloying elements include aluminum, titanium and / or niobium. The raw material for aluminum is aluminum ingot, with an aluminum content ≥99.7%, an oxygen content ≤0.02%, and a nitrogen content ≤0.05%. The raw material for titanium is pure titanium ingot produced by vacuum arc melting, with a titanium content ≥99.7%, oxygen content ≤0.05%, and nitrogen content ≤0.01%. The raw materials for niobium are pure niobium blocks or nickel-niobium master alloys, with an oxygen content of ≤0.05% and a nitrogen content of ≤0.01%.

8. The control method according to claim 1, characterized in that, In step 4, the temperature of the alloy liquid A is adjusted to 1430~1520℃, and then a deoxidizer with a mass fraction of 0.002~0.040 wt% is added to the alloy liquid A, stirred for 3~20 min, and allowed to stand for 3~10 min.

9. The control method according to claim 1, characterized in that, In step 4, during the casting process, the vacuum degree is ≤0.5hPa, and an insulating riser is used. The ratio of the weight of the molten metal in the riser to the total weight of the ingot is 0.03~0.

1.

10. The control method according to claim 1, characterized in that, In step 4, the deoxidizer is a magnesium-cerium alloy, and the cerium content in the magnesium-cerium alloy is 15~30 wt%.

Images