Smelting and forging process of low-aluminum high-titanium nickel-based C263 alloy large-size cast ingot

Abstract

The invention discloses a smelting and forging process of a low-aluminum high-titanium nickel-based C263 alloy large-size cast ingot, and aims to provide a cast ingot with stable and reliable chemical components for a novel oxygen-enriched gas turbine combustion chamber inner shell rear ring forge piece so as to ensure that the performance of the forge piece meets the use of a gas turbine combustion chamber. According to the technical scheme, firstly, a vacuum induction furnace and a constant-melting-speed electroslag furnace (ESR) are adopted for smelting (phi 610 mm) cast ingots, the problem of inclusion of large ingot types of the alloy is solved, the forging ratio of large forgings is increased, and the finished product structure and the product performance are improved; and 2, the burning loss of the easily burnt element titanium is solved by adjusting the aluminum and titanium components of the electrode blank, adding titanium dioxide powder into the ternary pre-melting slag system and adding aluminum powder in the process, and the yield is improved. The method has the advantages that (1) the problem of large ingot inclusion is solved; (2) the stable yield of the easily burnt element titanium is ensured; (3) the macrostructure is qualified; (4) an electroslag process is adopted for replacing a consumable process for production for the first time, and the cost is reduced; and (5) large-size ingot casting solves the problem of insufficient forging ratio.

Description

Technical Field

[0001] This invention belongs to the field of iron-based high-temperature alloy material manufacturing, and specifically relates to a smelting and forging process for large-size ingots of low-aluminum, high-titanium, nickel-based C263 alloy. Background Technology

[0002] C263 alloy is a Ni-Cr-Co based precipitation-hardening wrought superalloy with a service temperature up to 850℃. The alloy exhibits good oxidation resistance below 800℃, high yield strength and creep strength, low susceptibility to strain-aging cracking, and good resistance to thermal fatigue. It also possesses good formability and weldability, making it suitable for manufacturing welded sheet metal structural components and load-bearing parts for the main combustion chamber and afterburner chamber of aero-engines.

[0003] In recent years, this alloy has been selected for use as the rear ring forging of the combustion chamber shell of gas turbines, and its specifications are becoming larger, with standard requirements: 1. Low magnification structure: Take one transverse low magnification sample from the beginning and end of each batch of finished bars and conduct a low magnification test. The test results should be free of defects such as shrinkage residue, inclusions, cracks, and porosity. The test method shall be performed in accordance with ASTM E340. 2. Mechanical properties: The mechanical properties conform to the specifications in Table 1; Table 1

[0004] To ensure that the performance of forgings meets the requirements of new oxygen-enriched gas turbines, it is currently necessary to study a smelting and forging process that provides ingots with stable and reliable chemical composition. Summary of the Invention

[0005] This invention discloses a smelting and forging process for large-size C263 alloy ingots with low aluminum and high titanium nickel base. The purpose is to provide ingots with stable and reliable chemical composition and a reasonable forging ratio for the rear ring forging of the combustion chamber shell of a new type of oxygen-enriched gas turbine, thereby ensuring that the performance of the forging meets the requirements of the new type of oxygen-enriched gas turbine.

[0006] Technical solution of the present invention: The process involves casting a Φ430mm electrode billet in a vacuum induction furnace, then smelting an electroslag ingot (Φ610mm) using constant melting rate electroslag remelting (ESR), and finally forging it into finished products using a high-speed forging machine.

[0007] 1. Electrode billet production using a vacuum induction furnace: (1) Minimal element loss during vacuum induction furnace smelting; aluminum and titanium composition adjusted according to electroslag loss patterns; (2) Effective degassing in the vacuum induction furnace; harmful gases such as oxygen and nitrogen dissolved in the molten metal easily escape; (3) The carbon deoxidation reaction under vacuum in the vacuum induction furnace effectively volatilizes and removes harmful trace elements with low melting points and high vapor pressures, such as lead, bismuth, tellurium, and thallium; (4) The electronic stirring action of the vacuum induction furnace ensures highly uniform temperature and composition within the molten pool; (5) Bottom-pouring method is used to cast electrode billets with a size of Φ430mm.

[0008] 2. Steel ingots are smelted using constant melting rate electroslag remelting (ESR): (1) The chemical composition of the steel ingot is shown in Table 2; Table 2

[0009] (2) Slag system: Ternary pre-melted slag system CaF2:Al2O3:CaO=75%:15%:10%; (3) Slag quantity: 100kg~130kg; (4) Melting rate: Melting rate set at 6.0kg / min~7.5kg / min; (5) Additives: An appropriate amount of titanium dioxide powder is added to the slag. The amount added is controlled according to the aluminum and titanium composition of the electrode billet. Aluminum powder is also added appropriately during the process to reduce titanium element loss; (6) The protective atmosphere electroslag remelting ingot specification is Φ610mm (see...). Figure 1 ).

[0010] 3. High-speed forging: The steel ingot is heated to 1160℃. After the steel ingot is fully heated, it is forged into Φ400mm~Φ530mm using a 7000-ton high-speed forging machine with a three-stage upsetting and drawing process. The deformation amount of each forging is controlled to be no less than 35%.

[0011] Explanation of the invention points: (1) The use of a vacuum induction furnace + constant melting rate electroslag furnace (ESR) for ingot smelting (Φ610mm) solves the problem of inclusions in large alloy ingots, increases the forging ratio of forgings, and improves the microstructure and performance of finished products; (2) By adjusting the aluminum and titanium composition of the electrode billet and adding titanium dioxide powder to the ternary pre-melting slag system and aluminum powder during the process, the loss of easily burned titanium element is solved, thereby improving the yield.

[0012] This invention has the following advantages: (1) It solves the problem of inclusions in large ingots by actively adsorbing and filtering inclusions through electroslag remelting; (2) It ensures a stable yield of titanium, an easily burnable element, by adjusting the aluminum and titanium composition in a vacuum induction furnace and adding titanium dioxide and aluminum powder during constant melting rate electroslag smelting; (3) It ensures the qualified low-magnification microstructure of large ingots with high alloy ratios by reasonably controlling the melting rate of constant melting rate electroslag smelting; (4) It is the first time that electroslag technology has been used to replace the self-consumable process, reducing costs; (5) It solves the problem of insufficient forging ratio by smelting large-size (Φ610mm) ingots using the method of this invention. Attached Figure Description

[0013] Figure 1 Images of Φ610mm steel ingots produced by electroslag remelting; Figure 2 Example 1: Low-magnification corrosion image of the finished forging; Figure 3 Example 2: Low-magnification corrosion image of the finished forging; Figure 4 Example 3: Low-magnification corrosion image of the finished forging. Detailed Implementation

[0014] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. Embodiments 1 to 3 all adopt the same process flow: casting Φ430mm electrode billet in a vacuum induction furnace + smelting Φ610mm electroslag remelting (ESR) ingots by constant melting rate electroslag remelting → forging into finished products by a high-speed forging machine.

[0015] The element loss during the smelting process using a vacuum induction furnace is minimal. The aluminum and titanium composition can be adjusted according to the electroslag loss pattern to avoid unqualified chemical composition due to electroslag loss. The aluminum and titanium content of the vacuum induction furnace electrode billet is shown in Table 3. The vacuum induction furnace effectively degasses, and harmful gases such as oxygen and nitrogen dissolved in the molten metal can easily escape. The oxygen and nitrogen content of the gases is shown in Table 4. Steel ingots were smelted using constant melting rate electroslag remelting (ESR). The ternary pre-melted slag system was CaF2:Al2O3:CaO = 75%:15%:10%. Melting rate was set at 6.0 kg / min. Additives were added to reduce the loss of aluminum and titanium elements, based on their content. Example 1: 130 kg of slag, with 2 kg of titanium dioxide powder added, and 0.8 kg of aluminum powder added during the process. Example 2: 130 kg of slag, with 2.5 kg of titanium dioxide powder added, and 0.8 kg of aluminum powder added during the process. Example 3: 130 kg of slag, with 2.5 kg of titanium dioxide powder added, and 0.8 kg of aluminum powder added during the process. The chemical composition test results are shown in Table 5.

[0016] The steel ingots produced by the high-speed forging machine are heated to 1160℃. After the steel ingots are fully heated, a three-stage upsetting and drawing process is adopted using a 7000-ton high-speed forging machine. The deformation amount of each heat is controlled to be no less than 35%. Various specifications are forged in a package: Example 1: Φ400mm, Example 2: Φ400mm, Example 3: Φ500mm.

[0017] Test results: (1) Low-magnification microstructure inspection passed; low-magnification corrosion image of the finished forging (see Example 1) Figure 2 See Example 2 Figure 3 See Example 3 Figure 4 ); (2) The results of the mechanical property test are shown in Table 6.

[0018] Table 3

[0019] Table 4

[0020] Table 5

[0021] Table 6

Claims

1. A smelting and forging process for large-size ingots of low-aluminum, high-titanium, nickel-based C263 alloy, characterized in that, (1) The smelting process: ① Electrode billets are produced using a vacuum induction furnace: the aluminum and titanium composition is adjusted according to the electroslag burn-off characteristics; the vacuum induction furnace effectively degasses the metal, allowing harmful gases such as oxygen and nitrogen dissolved in the molten metal to escape easily; it effectively volatilizes and removes harmful trace elements with low melting points and high vapor pressures, such as lead, bismuth, tellurium, and thallium; electronic stirring ensures highly uniform temperature and composition within the molten pool; and the bottom-pouring method is used to cast electrode billets with a size of Φ430mm. ② Steel ingots smelted using constant melting rate electroslag remelting: Chemical composition of the steel ingots (mass fraction, / %): Carbon: 0.04%–0.08%, Chromium: 19.00%–21.00%, Iron: not more than 0.7%, Cobalt: 19.00%–21.00%, Aluminum: 0.30%–0.60%, Titanium: 1.90%–2.40%, Molybdenum: 5.60%–6.10%, Boron: not more than 0.005%, Copper: not more than 0.20%, Silicon: not more than 0.40%, Manganese: not more than 0.60%, Phosphorus: not more than 0.015%. Sulfur content not exceeding 0.007%, aluminum + titanium: 2.4%–2.8%, balance nickel; slag system: ternary pre-melted slag system CaF2:Al2O3:CaO = 75%:15%:10%; slag quantity: 100kg–130kg; melting rate: 6.0kg / min–7.5kg / min; additives: an appropriate amount of titanium dioxide powder is added to the slag, the amount added is controlled according to the aluminum and titanium composition of the electrode billet, and aluminum powder is added appropriately during the process to reduce the loss of titanium elements; the protective atmosphere electroslag remelting steel ingot specification is Φ610mm; (2) The forging process: The steel ingot is heated to 1160℃. After the steel ingot is fully heated, it is forged into a three-stage upsetting process using a 7000-ton high-speed forging machine. The deformation amount of each forging is controlled to be no less than 35%, and the ingot is forged into a sleeve to Φ400mm~Φ530mm.

2. The smelting and forging process for a large-size ingot of low-aluminum, high-titanium nickel-based C263 alloy according to claim 1, characterized in that, The vacuum induction furnace has an elemental titanium content of 2.31% and an aluminum content of 0.40%. The oxygen content of the gas in the vacuum induction furnace is 0.0005%, and the nitrogen content is 0.0025%. The constant melting rate electroslag remelting (ESR) steel ingot has a melting rate of 6.0 kg / min and a slag volume of 130 kg. 2 kg of titanium dioxide powder is added to the slag, and 0.8 kg of aluminum powder is added during the process. The steel ingot forged by the high-speed forging machine is heated to 1160℃. After the steel ingot is fully heated, it is subjected to a three-stage upsetting and drawing process using a 7000-ton high-speed forging machine. The deformation amount of each heat is controlled to be no less than 35%. The forging specification is Φ400mm. Chemical composition analysis results: Carbon: 0.062%, Chromium: 19.86%, Iron: 0.44%, Cobalt: 20.35%, Aluminum: 0.47%, Titanium: 2.00%, Boron: 0.0025%, Molybdenum: 5.81%, Copper: .01%, Silicon: 0.02%, Manganese: 0.44%, Phosphorus: 0.006%, Sulfur: 0.001%, Aluminum + Titanium: 2.47%, Balance Nickel; The low-magnification tissue examination was satisfactory. Mechanical property test results: 779℃ tensile properties: yield strength 462MPa, tensile strength 595MPa, elongation 25%; 779℃ 50h creep properties: stress 120MPa, elongation 0.03%; hardness HBW:

180.

3. The smelting and forging process for a large-size ingot of low-aluminum, high-titanium nickel-based C263 alloy according to claim 1, characterized in that, The vacuum induction furnace has an elemental titanium content of 2.32% and an aluminum content of 0.41%. The oxygen content of the gas in the vacuum induction furnace is 0.0007%, and the nitrogen content is 0.0024%. The constant melting rate electroslag remelting (ESR) steel ingot has a melting rate of 6.0 kg / min and a slag volume of 130 kg. 2.5 kg of titanium dioxide powder is added to the slag, and 0.8 kg of aluminum powder is added during the process. The steel ingot forged by the high-speed forging machine is heated to 1160℃. After the steel ingot is fully heated, it is subjected to a three-stage upsetting and drawing process using a 7000-ton high-speed forging machine. The deformation amount of each heat is controlled to be no less than 35%. The forging specification is Φ400mm. Chemical composition analysis results: Carbon: 0.063%, Chromium: 19.81%, Iron: 0.39%, Cobalt: 20.40%, Aluminum: 0.4%, Titanium: 2.31%, Boron: 0.0030%, Molybdenum: 5.76%, Copper: 0.01%, Silicon: 0.02%, Manganese: 0.45%, Phosphorus: 0.005%, Sulfur: 0.001%, Aluminum + Titanium: 2.60%, Balance: Nickel; The low-magnification tissue examination was satisfactory. Mechanical property test results: Tensile properties at 779℃: yield strength 462MPa, tensile strength 542.5MPa, elongation 26.5%; Creep properties at 779℃ for 50h: stress 120MPa, elongation 0.05%; Hardness HBW:

183.

4. The smelting and forging process for large-size low-aluminum, high-titanium nickel-based C263 alloy ingots according to claim 1, characterized in that, The vacuum induction furnace has an elemental titanium content of 2.32% and an aluminum content of 0.41%. The oxygen content of the gas in the vacuum induction furnace is 0.0007%, and the nitrogen content is 0.0024%. The constant melting rate electroslag remelting (ESR) steel ingot has a melting rate of 6.0 kg / min and a slag volume of 130 kg. 2.5 kg of titanium dioxide powder is added to the slag, and 0.8 kg of aluminum powder is added during the process. The steel ingot forged by the high-speed forging machine is heated to 1160℃. After the steel ingot is fully heated, it is subjected to a three-stage upsetting and drawing process using a 7000-ton high-speed forging machine. The deformation amount of each heat is controlled to be no less than 35%. The forging specification is Φ400mm. Chemical composition analysis results: Carbon: 0.063%, Chromium: 19.81%, Iron: 0.39%, Cobalt: 20.40%, Aluminum: 0.4%, Titanium: 2.31%, Boron: 0.0030%, Molybdenum: 5.76%, Copper: 0.01%, Silicon: 0.02%, Manganese: 0.45%, Phosphorus: 0.005%, Sulfur: 0.001%, Aluminum + Titanium: 2.60%, Balance: Nickel; The low-magnification tissue examination was satisfactory. Mechanical property test results: Tensile properties at 779℃: yield strength 462MPa, tensile strength 542.5MPa, elongation 26.5%; Creep properties at 779℃ for 50h: stress 120MPa, elongation 0.05%; Hardness HBW: 183.

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