High-purity solid solution strengthening high-temperature alloy rod and preparation method thereof

Abstract

The application discloses a kind of high-purity solid solution strengthening high-temperature alloy rod and its preparation method, belongs to high-temperature alloy hot working technical field, specifically includes the following steps: step one vacuum induction smelting, step two electroslag remelting, step three ingot homogenization treatment, step four forging breakdown and material, step five heat treatment.The high-purity rod prepared by the application has significantly reduced non-metallic inclusions, more uniform structure, can reduce the gas content of the material, reduce inclusions, improve purity, effectively solve the problem of poor hot plasticity of GH3128 alloy rod, can meet the needs of long-life work of engine parts under high-temperature conditions, realize the engineering application of the material.The alloy rod prepared by the process of the application has wide application prospect in the preparation of aero-engine parts.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature alloy hot working technology, and specifically relates to a high-purity solid solution strengthened high-temperature alloy bar and its preparation method. Background Technology

[0002] GH3128 alloy is mainly strengthened by solid solution with W and Mo, and the grain boundaries are strengthened with elements such as B, Ce, and Zr. It has high plasticity, creep strength and good processing performance. Its comprehensive performance is higher than nickel-based solid solution alloys such as Hastelloy X. It is suitable for manufacturing combustion chamber flame tubes, afterburner shells, regulating plates and other high-temperature components of aero-engines that operate at 950°C for a long time. The main products are cold-rolled sheets, but hot-rolled sheets, bars, forgings, wires and tubes can also be supplied.

[0003] Early GH3128 alloy bars utilized the same plate melting process as induction furnaces, specifically a non-vacuum induction furnace combined with an electroslag furnace. The non-vacuum induction furnace process melts the alloy in an atmospheric environment, resulting in high gas content and numerous inclusions in the GH3128 bars. Furthermore, the bar forging process was poorly matched to these inclusions, leading to a high risk of severe cracking during forging. Due to technological advancements, aero-engines now demand increasingly stringent material quality standards, necessitating the development of high-performance alloys with superior overall properties. This invention discloses a method for preparing high-purity solid solution-strengthened high-temperature alloy bars, which reduces gas content, minimizes inclusions, and improves purity, effectively addressing the issue of poor thermoplasticity in alloy bars. Summary of the Invention

[0004] The purpose of this invention is to provide a high-purity solid solution strengthened high-temperature alloy bar and its preparation method. This invention improves the purity of the material by reducing the gas content, reducing inclusions, and implementing a systematic preparation process including ingot homogenization and heat treatment. This effectively solves the problem of poor thermoplasticity of alloy bars leading to forging cracks, thereby meeting the needs of long-life operation of engine components under high-temperature conditions, realizing the engineering application of the material, and meeting the needs of engine manufacturing.

[0005] Material purity is the primary factor in material quality, directly affecting its durability, plasticity, component lifespan, and reliability. Improving material purity requires reducing the content of S, P, Si, gaseous N, O, and trace elements. To improve material performance and meet operating conditions, the composition of the high-purity solid solution strengthened high-temperature alloy bar was determined through numerical simulation. The composition, by mass percentage, is as follows: C≤0.03%, Mn≤0.40%, Si≤0.50%, S≤0.005%, P≤0.005%, O≤0.0020%, N≤0.0090%, Cr 19.0~21.0%, Mo 7.5~9.0%, W 7.5~8.5%, Al 0.4~0.8%, Ti 0.4~0.8%, Fe≤2.0%, B≤0.005%, Ce≤0.05%, Zr≤0.06%, Ni balance.

[0006] Based on the material's compositional characteristics and to ensure its purity, the material preparation process is as follows: raw material preparation → vacuum induction furnace smelting → electroslag remelting → ingot homogenization treatment → press billet opening → radial forging mill billet opening → forging and rolling into finished products → heat treatment.

[0007] Specifically, the process includes the following steps: Step 1: Vacuum induction smelting; Step 2: Electroslag remelting; Step 3: Ingot homogenization treatment; Step 4: Forging and billet preparation; Step 5: Heat treatment.

[0008] Step 1: Vacuum induction furnace smelting:

[0009] Nickel plates are placed at the bottom of the charging bucket, while chromium, molybdenum, and tungsten are placed in the middle. After the other raw materials are melted, aluminum and titanium are added to obtain the furnace charge. Power-up casting is carried out under vacuum conditions of ≤5Pa, and the casting speed is controlled. During the casting process, shrinkage is compensated to reduce shrinkage cavities. Before tapping, the steel is calmed under vacuum, purged with argon, then the vacuum is broken, left to stand, and demolded for air cooling to obtain the ingot. The ingot is then homogenized and kept at a constant temperature.

[0010] In step one, the pouring temperature is controlled at 1450-1500℃; before tapping, the steel is cooled under vacuum for 60-70 minutes; after standing for 100-130 minutes, it is demolded and air-cooled.

[0011] Step 2, Electroslag Remelting:

[0012] A typical 70CaF2-30CaO binary slag system was used for smelting in an electroslag furnace under a protective atmosphere. During the smelting process, the thermal boundary conditions and current of the electroslag furnace were controlled. The changes in the cooling water flow rate and inlet and outlet water temperature in the crystallizer water jacket were small. The melting rate was monitored and found to be free of abnormal fluctuations, resulting in remelted steel ingots. After cooling, the steel ingots were demolded and air-cooled. Samples were taken and tested to ensure that the composition of the electroslag ingots was within the predetermined range.

[0013] In step two, the melting range of the slag is 1120–1330℃; during normal smelting, the melting rate is 4–6 kg / min.

[0014] In step two, the water inflow and current input settings are as follows:

[0015] Crystallizer water jacket cooling water data: Cooling water inlet temperature 25–32℃, cooling water outlet temperature 46–60℃, cooling water flow rate 16 m³ / h. 3 / min;

[0016] Cooling water data for the cold water base plate: Cooling water inlet temperature 25-35℃, cooling water outlet temperature 31-40℃, cooling water flow rate 12m³ / h. 3 / min;

[0017] Effective current (sinusoidal root mean square current): 5.8kA;

[0018] Furnace opening voltage (voltage between electrode furnace opening end and ground): 38V.

[0019] Step 3: Homogenization treatment of ingots:

[0020] The employed smelting process effectively reduced elemental segregation and oxygen / nitrogen content in the ingot, decreasing inclusions such as oxides and carbonitrides. However, the alloy contains high levels of solid solution strengthening elements W and Mo, and second-phase strengthening elements Al and Ti, resulting in a high degree of alloying. The melting points and densities of W and Mo differ significantly from those of Al and Ti. This difference in melting points and densities leads to substantial elemental segregation during ingot solidification after smelting. This segregation is primarily manifested in the compositional segregation between dendrite trunks and interdendritic regions of the ingot microstructure. Due to this elemental segregation, a large amount of primary carbides agglomerate in the interdendritic region. These carbides are mainly distributed in large, angular aggregates, forming areas of high stress concentration during deformation and often serving as initiation sites for forging cracks during the forging process. The original microstructure of the ingot, as observed under a 100x microscope, is shown below. Figure 1 The internode spacing is between 70μm and 110μm.

[0021] The above problems can be solved by homogenization treatment of the ingot. After homogenization treatment, the alloying elements in the carbides gradually diffuse into the matrix, and the morphology and distribution of the carbides change significantly. The size becomes smaller, the edges become blunt, and the distribution changes from a series of blocky distributions to a discontinuous granular distribution. This change is extremely beneficial to improving the hot working plasticity of the ingot forging and the internal quality of the alloy.

[0022] The as-cast heat treatment process used in this invention is 1200-1250℃. According to the test results, the homogenization treatment temperature in this invention should be lower than 1250℃, and long-term homogenization treatment is beneficial to improving the hot working plasticity of the ingot and the internal quality of the alloy.

[0023] Step 4: Forging and Finishing:

[0024] After polishing, the electroslag ingot is forged on a high-speed forging mill. After forging, it is heated to a set temperature and held at that temperature, followed by radial forging, and then flaw detection. Specifically, this includes:

[0025] S1 forged bar production: The steel ingot is formed by a combination of fast forging and radial forging deformation process. After the ingot is forged, it is then upset.

[0026] S2 rolled bar: The billet is produced by radial forging in one heat, and then rolled by a rolling mill after heating. The billet is finished and polished after no more than three heats of rolling.

[0027] The processing temperature is controlled between 950 and 1100℃, and the strain rate is between 0.1 and 0.5 s. -1 The grain size can be controlled to be below 10 μm; when the temperature is above 1050℃, most of the carbides in the matrix have dissolved back, so the suitable processing range for the material is: deformation temperature 1050~1100℃, strain rate 0.1~0.5s. -1 ;

[0028] After the electroslag ingot is polished, it is forged on a high-speed forging machine. Before forging, it is heated to 1170-1180℃, the initial forging temperature is 1000℃, and the final forging temperature is 850-900℃.

[0029] Before radial forging, heat to 1080℃ and hold at that temperature. The furnace temperature is 1080℃. When transferring to the transfer table, the temperature is maintained at 1050℃. The transportation time is controlled within 120-130 seconds.

[0030] The heating process of the steel ingot before forging is as follows:

[0031] Furnace loading temperature: ≤700℃, first heat to 900℃, heating time ≥5h, then heat to 1160℃; then heat to 1160℃, heating time ≥1.6h;

[0032] Heating temperature: 1170~1190℃, 890~910℃, holding time ≥3h, 1160~1180℃, holding time ≥3h;

[0033] S1 forged bar finished product

[0034] The process employs a combination of fast forging and radial forging deformation. After the steel ingot is forged, it is gently pulled out and then upset.

[0035] First heat: Strike the tail end with 150*(450~500)mm pliers, and when returning to the furnace, the pliers should face inwards. Keep warm for ≥2 hours.

[0036] Second heat: To improve surface quality and cast crystal structure, the surface is lightly tapped to induce micro-deformation. Each hammer blow reduces the surface by ≤20mm. The surface is then held in the furnace for ≥2 hours.

[0037] Third heat: Upset to 3 / 5 of the original height. Return to furnace and hold for ≥2 hours, with each hammer blow reducing the thickness by ≤36mm.

[0038] Forge to the required dimensions.

[0039] The alloy steel ingot produced by vacuum induction and electroslag remelting exhibits good plasticity during forging, low deformation resistance, no surface cracks, and is insensitive to forging temperature and deformation per pass. No cracks are generated at low temperatures, and the maximum deformation per pass can reach 50%, which greatly improves the forging plasticity of the alloy and allows for post-forging flaw detection.

[0040] S2 rolled bar finished product

[0041] The radial forging process is adopted, and the 100-140mm square billet is formed in one radial forging. The radial forging heating temperature is controlled at 1160-1170℃, and the elongation coefficient is controlled at 1.30-1.40. The forging process has good elongation and plasticity, and there are no cracks on the surface after forging.

[0042] Before entering the rolling process, the billet is heated to 1160-1180℃, the rolling entry temperature is ≥970℃, the final rolling temperature is ≥950℃, and the rolling rhythm is 100-130s / piece.

[0043] The heating process parameters for the rolled billet are as follows:

[0044] Billet specifications (mm): 100~140mm square, preheating zone temperature (°C): ≤900, heating zone temperature (°C): 1130~1180, soaking zone temperature (°C): 1160~1180, temperature difference between the positive and negative sides (°C): ≤15, total heating time (min): ≥120, final rolling temperature (°C): ≥950, rolling rhythm: 100~130s / piece, cooling method: air cooling.

[0045] Step 5, Heat Treatment:

[0046] The heat treatment regime for the samples is 950–1200℃, with a holding time of 1–2 hours; based on the actual production application requirements for material properties, the preferred heat treatment temperature is 1150–1200℃.

[0047] The beneficial effects of this invention are:

[0048] The alloy rods prepared by the process of this invention have high purity, good thermoplasticity, and good comprehensive performance. This alloy has broad application prospects in the preparation of aero-engine parts.

[0049] Scanning electron microscopy analysis was performed on the original sample and the finished bar sample, as shown in the figures below. Figure 6 and Table 1, Figure 7 As shown in Table 2, comparative analysis reveals that heat treatment and processing techniques can effectively optimize the degree of segregation. A comparison of non-metallic inclusions in bars of different purities is shown in Table 2. Figure 8 As shown in Table 3, the high-purity rods prepared by this invention have significantly reduced non-metallic inclusions and more uniform microstructure.

[0050] The preparation process of this invention can reduce the gas content of the material, reduce inclusions, improve purity, and effectively solve the problem of poor thermoplasticity of GH3128 alloy rods.

[0051] The alloy rods prepared by the method of this invention meet the requirements of long-life operation of engine components under high-temperature conditions, realize the engineering application of materials, meet the needs of engine manufacturing, and can also be widely used in other engines, with broad application prospects.

[0052] The smelting process selected in this invention effectively reduces elemental segregation and oxygen and nitrogen content in the ingots, and reduces inclusions such as oxides and carbonitrides. Scanning electron microscopy analysis of the original sample and the finished bar sample shows that the heat treatment and processing technology can effectively optimize the degree of segregation. The high-purity bar prepared by this invention has significantly reduced non-metallic inclusions and a more uniform microstructure.

[0053] In this invention, the ingot undergoes homogenization treatment, which solves the problem of a large amount of primary carbides agglomerated in the interdendritic region due to significant compositional segregation between dendrites and dendrites in the ingot structure after smelting. After homogenization treatment, alloying elements in the carbides gradually diffuse into the matrix, and the morphology and distribution of the carbides change significantly. The size decreases, the edges become blunt, and the distribution changes from a series of blocky structures to a discontinuous granular distribution, thereby reducing the probability of forging crack initiation during the forging process.

[0054] In the forging process, the present invention controls the processing temperature and strain rate to keep the grain size below 10 μm and ensure that most of the carbides in the matrix dissolve back.

[0055] This invention employs a process combining vacuum induction and electroslag remelting. The alloy steel ingot exhibits good plasticity during forging, low deformation resistance, and no surface cracks. It is insensitive to forging temperature and deformation per pass, with no cracks generated at low temperatures. The maximum deformation per pass can reach 50%, which greatly improves the forging plasticity of the alloy.

[0056] The heat treatment of this invention adopts a solution treatment method, and the temperature of the solution treatment is controlled to ensure the hardness, strength, plasticity and durability of the alloy bar while ensuring the tensile properties.

[0057] Table 1. Scanning electron microscopy analysis results

[0058]

[0059] Table 2. Scanning electron microscopy analysis results

[0060]

[0061] Table 3 Comparison of non-metallic inclusions in bars with different purity levels

[0062] Bar categories N content Category A Category B Category C Category D Nitrogen compounds High purity 82ppm 0 0.5 0 1.0 / 0 0.5 / 0 ordinary 305ppm 0 0.5 0 1.0 / 0 1.5 / 2.0 Attached Figure Description

[0063] Figure 1 Original microstructure of the ingot;

[0064] Figure 2 Microstructure of 1 / 2R section of electroslag ingot after heat treatment; (a) 1180℃, (b) 1200℃, 1200℃, (c) 1220℃;

[0065] Figure 3 The morphology of tissues and carbides at different homogenization temperatures: (a) 1200℃ for 30 min, (b) 1250℃ for 30 min, (c) 1300℃ for 30 min, (d) 1330℃ for 30 min.

[0066] Figure 4 Grain size at 1 / 2R of bar sheet under different heat treatment regimes: (a) Original state, grain size 6-8, average grain size 7; (b) 950℃, grain size 5-7, average grain size 6; (c) 1000℃, grain size 5-7, average grain size 6; (d) 1050℃, grain size 3-7, double grain; (e) 1100℃, grain size 0-6, double grain; (f) 1150℃, grain size 2-4, 3; (g) 1180℃, grain size 2-4, 3.

[0067] Figure 5 Carbide morphology at 1 / 2R of bar sheet under different heat treatment regimes: (a) original state, carbide morphology is network distribution, (b) 950℃*2h, carbide morphology is banded distribution, (c) 1000℃*2h, carbide morphology is banded distribution, (d) 1050℃*2h, carbide morphology is banded distribution, (e) 1100℃*2h, carbide morphology is banded distribution, (f) 1150℃*2h, carbide morphology shows obvious dissolution, (g) 1180℃*2h, carbide morphology shows further dissolution;

[0068] Figure 6 Scanning electron microscopy analysis results of the original sample;

[0069] Figure 7 Scanning electron microscopy analysis results of finished bar samples;

[0070] Figure 8 Comparison of non-metallic inclusions in bars of different purities; (a) high-purity bars of the present invention, (b) ordinary bars. Detailed Implementation

[0071] Example 1

[0072] A high-purity solid solution strengthened high-temperature alloy rod and its preparation method, specifically including the following steps:

[0073] Step 1: Vacuum induction furnace smelting:

[0074] The raw materials consist of nickel plates, metallic chromium, metallic molybdenum, metallic tungsten, metallic aluminum, metallic titanium, and sponge zirconium. All raw materials are clean, free from oil, rust, dust, and other contaminants, and their surface finish, composition, and particle size all meet relevant requirements. The metal materials are baked before use. The furnace charge weight is 1 ton.

[0075] Casting is carried out under an ultimate vacuum of ≤2.0 Pa, controlling the casting speed and temperature between 1450 and 1500℃. Attention is paid to feeding to minimize shrinkage cavities. Before tapping, the steel is cooled under vacuum for 60–70 minutes, then purged with Ar at 3000 Pa, followed by vacuum breaking. After 120 minutes, the steel is demolded and air-cooled. The risers and flattened ends of the cast Φ250mm electrode rods are removed, and the surface is polished before electroslag remelting.

[0076] Step 2, Electroslag Remelting:

[0077] A typical 70CaF2-30CaO binary slag system was used for smelting in an electroslag remelting furnace under a protective atmosphere. The thermal boundary conditions and current of the electroslag remelting furnace were controlled during the smelting process. The melting range of the slag was 1125–1330℃. The melting rate was 4.5 kg / min. After cooling for 60–70 minutes, the Φ420mm electroslag ingot was demolded and air-cooled.

[0078] Electroslag ingot alloy composition: by mass percentage: C 0.028%, Mn 0.23%, Si 0.30%, S 0.001%, P 0.003%, O 0.0016%, N 0.0020%, Cr 20.8%, Mo 8.19%, W 7.9%, Al 0.62%, Ti 0.71%, Fe 0.29%, B 0.002%, Ce 0.009%, Zr 0.021%, Ni balance.

[0079] In step two, the water inflow and current input settings are as follows:

[0080] Crystallizer water jacket cooling water data: Cooling water inlet temperature 25-26℃, cooling water outlet temperature 46-50℃, cooling water flow rate 16m³ / h. 3 / min;

[0081] Cooling water data for the cold water base plate: Cooling water inlet temperature 25-35℃, cooling water outlet temperature 31-33℃, cooling water flow rate 12m³ / h. 3 / min;

[0082] Effective current (sinusoidal root mean square current): 5.8kA;

[0083] Furnace opening voltage (voltage between electrode furnace opening end and ground): 38V.

[0084] Step 3: Homogenization treatment of ingots:

[0085] The as-cast heat treatment regime is shown in Table 4, and the microstructure after as-cast heat treatment is shown in Table 4. Figure 2 Experiments revealed that as the heat treatment temperature and time increased, the proportion of interdendritic particles decreased, resulting in greater dispersion. The alloy's compositional homogenization could reach a relatively ideal state in a short time. This demonstrates that using high-temperature, short-duration heating methods improves product homogenization, providing a reference for subsequent product heating and forging processes.

[0086] Table 4. Heat treatment regime for as-cast state

[0087]

[0088] To further determine the homogenization temperature, four homogenization temperatures were used: 1200℃ for 30 min, 1250℃ for 30 min, 1300℃ for 30 min, and 1330℃ for 30 min. Changes in carbides and microstructure were observed. The microstructure and carbide morphology at different homogenization temperatures are shown in [Figure number missing]. Figure 3 The experimental results show that as the processing temperature increases, the grains grow significantly and the grain boundaries weaken, approaching overheating. At 1200℃, a large amount of carbides remain undissolved in the microstructure. At 1250℃, the microstructure mainly retains golden TiN and primary carbides, and the M6C phase is basically dissolved into the matrix, but the grain boundaries begin to weaken. At temperatures above 1250℃, the carbides dissolve further, but the microstructure begins to show signs of overheating.

[0089] Therefore, in this embodiment, the ingot homogenization treatment process is carried out at 1200℃ for 6 hours.

[0090] Step 4: Forging and Finishing:

[0091] After polishing, the electroslag ingot is forged on a 2000-ton high-speed forging mill. The forging heating temperature is 1170℃, the initial forging temperature is 1000℃, the final forging temperature is 900℃, and the strain rate is 0.1s. -1 ;

[0092] Furnace temperature: 1080℃, transfer platform: 1050℃, transport time: 130s;

[0093] S1 forged bar finished product

[0094] The deformation process adopts a combination of 3150t fast forging and 1800t radial forging. After the steel ingot is forged, it is gently pulled out and then upset.

[0095] First heat: Attach a 150*460mm pliers handle to the tail end, and when returning it to the furnace, have the pliers handle facing inwards, and keep it warm for 2.5 hours.

[0096] Second heat: To improve surface quality and cast crystal structure, the surface is lightly tapped to induce micro-deformation. Each hammer blow reduces the surface thickness by 15mm. The furnace is then held at this temperature for 2.5 hours.

[0097] Third heat: Upset to 3 / 5 of the original height. Return to the furnace and hold for 2 hours, with each hammer blow reducing the height by 32mm.

[0098] Fourth heat: Forge to 390°C. Return to furnace and hold for 2.5 hours. Each hammer blow reduces the diameter by 32mm.

[0099] Fifth heat: Forge to 350 octagonal. Return to furnace and hold for 2.5 hours. Each hammer blow reduces the diameter by 32mm.

[0100] Sixth hammer blow: Forge to 280 mm. Return to furnace and hold for 2.5 hours. Each hammer blow reduces the diameter by 32 mm.

[0101] Seventh heat: Forge to 250 degrees Celsius (8-point). Return to the furnace and keep warm for 2.5 hours.

[0102] Eighth hammer blow: Forge to 180 degrees octagon, then return to the furnace and hold for 2.5 hours. Each hammer blow reduces the diameter by 32mm.

[0103] Ninth strike: Strike a 180mm diameter ball, cut off the head with 30kg. Each hammer blow reduces the pressure by 32mm.

[0104] Post-forging flaw detection;

[0105] S2 rolled bar finished product

[0106] The 1300-ton radial forging process is adopted to forge a 140mm square billet in one pass. The radial forging heating temperature is controlled at 1170℃ and the elongation coefficient is controlled at 1.30. The forging process has good elongation and plasticity, and there are no cracks on the surface after forging.

[0107] The billet is produced using a continuous rolling mill with an inlet temperature of 980℃, a heating temperature of 1170℃, and a final rolling temperature of 950℃. The billet is rolled to Φ37mm and then finished and polished to Φ35mm.

[0108] Step 5, Heat Treatment:

[0109] The grain size was examined under a microscope at 100x magnification; see the results below. Figure 4 From the grain size structure under different heat treatment conditions, the alloy can undergo recrystallization transformation in the range of 1000 to 1050℃, and the grain size gradually increases with increasing temperature.

[0110] The morphology of the carbides was examined under a microscope at 100x magnification. (See attached image.) Figure 5 As the temperature rises, the carbides gradually dissolve back, and a relatively uniform distribution can be achieved at 1180℃.

[0111] Mechanical properties were tested at four temperature points ranging from 1140 to 1200℃ (see Tables 5 and 6). The results show that after one hour of solution treatment at all four temperature points, the room temperature tensile properties meet the requirements of existing technical specifications. With increasing solution temperature, strength and hardness show a slight decreasing trend. Similarly, in high-temperature tensile properties, strength shows a slight decreasing trend with increasing solution temperature, while plasticity changes are not significant. The actual high-temperature tensile test results at 950℃ all meet the existing technical requirements. b (MPa)≥180, δ5(%)≥40, ψ(%)≥40; High-temperature creep performance at 950℃: With the increase of solution temperature, both time and plasticity show an upward trend. However, the creep time of the sample treated with solution at 1140~1160℃ did not reach 25 hours, while the creep time of the sample treated with solution at 1190~1200℃ was greater than 25 hours.

[0112] Table 5. Tensile and hardness properties of alloys under different heat treatment regimes

[0113]

[0114]

[0115] Table 6 High-tensile and creep properties of alloys under different heat treatment regimes

[0116]

[0117] Therefore, in this embodiment, the solution treatment process is 1190±10℃, held for 1 hour, and then air-cooled.

[0118] Example 2

[0119] A high-purity solid solution strengthened high-temperature alloy rod and its preparation method are disclosed. The operation steps are the same as in Example 1, with the following differences:

[0120] Step 3: Homogenization treatment of ingots:

[0121] In this embodiment, the ingot homogenization treatment process is carried out at 1250℃ for 6 hours.

[0122] Step 5, Heat Treatment:

[0123] In this embodiment, the solution treatment process is 1160±10℃, held for 1 hour, and then air-cooled.

[0124] Example 3

[0125] A high-purity solid solution strengthened high-temperature alloy rod and its preparation method are disclosed. The operation steps are the same as in Example 1, with the following differences:

[0126] Step 3: Homogenization treatment of ingots:

[0127] In this embodiment, the ingot homogenization treatment process involves heating at 1230℃ for 6 hours. Step 5: Heat treatment:

[0128] In this embodiment, the solution treatment process is 1180±10℃, held for 1 hour, and then air-cooled.

Claims

1. A method for preparing high-purity solid solution strengthened high-temperature alloy rods, characterized in that, The composition of this high-purity solid solution strengthened high-temperature alloy bar, by mass percentage, is: C≤0.03%, Mn≤0.40%, Si≤0.50%, S≤0.005%, P≤0.005%, O≤0.0020%, N≤0.0090%, Cr 19.0~21.0%, Mo 7.5~9.0%, W 7.5~8.5%, Al 0.4~0.8%, Ti 0.4~0.8%, Fe≤2.0%, B≤0.005%, Ce≤0.05%, Zr≤0.06%, Ni balance. The specific preparation method includes the following steps: Step 1: Vacuum induction furnace smelting: Nickel plates are placed at the bottom of the charging bucket, while chromium, molybdenum, and tungsten are placed in the middle. After the other raw materials are melted, aluminum and titanium are added to obtain the furnace charge. Power casting is carried out under vacuum conditions of ≤5Pa, and the casting speed is controlled. During the casting process, shrinkage is compensated to reduce shrinkage cavities. Before the alloy is unloaded, it is calmed under vacuum, purged with argon, then the vacuum is broken, and the ingot is allowed to stand and demolded for air cooling to obtain the ingot. Step 2, Electroslag Remelting: A typical 70CaF2-30CaO binary slag system was used for smelting in an electroslag furnace under a protective atmosphere. During the smelting process, the thermal boundary conditions and current of the electroslag furnace were controlled to obtain the remelted alloy ingot. After cooling, the alloy ingot was demolded and air-cooled. The composition of the electroslag ingot was sampled and tested and found to be within the predetermined range. Step 3: Homogenization treatment of ingots: The heat treatment process used for the ingots is 1200–1250℃; Step 4: Forging and Finishing: After the electroslag ingot is polished, it is forged on a high-speed forging mill. After forging, it is heated to the set temperature and held at that temperature. Then, it is radially forged and inspected for defects after forging. Processing strain rate: 0.1–0.5 s -1 The grain size is controlled to be less than 10μm; After the electroslag ingot is polished, it is forged on a high-speed forging mill. The forging heating temperature is 1170-1180℃, the initial forging temperature is 1000℃, and the final forging temperature is 850-900℃. Before radial forging, heat to 1080℃ and hold at that temperature. The furnace temperature is 1080℃. When transferring to the transfer table, the temperature is maintained at 1050℃. The transportation time is 130s. Heating process of alloy ingots before forging: Furnace loading temperature ≤700℃, slowly rise to 900℃, heating time ≥5h, then rise to 1160℃, heating time ≥1.6h; heating temperature 1170~1190℃, holding time at 890~910℃ ≥3h, holding time at 1160~1180℃ ≥3h; Specifically, it includes: S1 forged bar production: The alloy ingot is formed by a combination of fast forging and radial forging deformation process. After the forging is completed, it is upsetting. First heat: Φ150*(450~500)mm clamps are applied to the tail end. When returning to the furnace, the clamps should face inwards and the heat should be maintained for ≥2 hours. Second heat: Lightly tap the surface to cause slight deformation, with each hammer press down ≤20mm, then return to the furnace for heat preservation ≥2 hours; Third heat: Upset to 3 / 5 of the original height, then return to the furnace for heat preservation for ≥2 hours, with each hammer press-down amount ≤36mm; Continue forging to the specified size; S2 rolled bars are produced using a radial forging process, producing 100-140mm square billets in a single radial forging operation. The radial forging heating temperature is controlled at 1160-1170℃, and the elongation coefficient is controlled at 1.30-1.

40. Before rolling, the billets are heated to 1160-1180℃, the rolling entry temperature is ≥970℃, the final rolling temperature is ≥950℃, and the rolling rhythm is 100-130s / piece. After rolling, the billets are finished and polished. Step 5, Heat Treatment: The heat treatment regime for the samples was 950–1200℃, with a holding time of 1–2 hours.

2. The method for preparing a high-purity solid solution strengthened high-temperature alloy rod according to claim 1, characterized in that, In step one, the pouring temperature is controlled at 1450-1500℃; the alloy is cooled under vacuum for 60-70 minutes before being poured out; after standing for 100-130 minutes, it is demolded and air-cooled; the ingot is homogenized at 1200℃ and held for 6 hours.

3. The method for preparing a high-purity solid solution strengthened high-temperature alloy rod according to claim 1, characterized in that, In step two, the melting range of the slag is 1120–1330℃; the melting rate is 4–6 kg / min.

4. The method for preparing a high-purity solid solution strengthened high-temperature alloy rod according to claim 1, characterized in that, In step two, the water inflow and current input settings are as follows: Crystallizer water jacket cooling water data: Cooling water inlet temperature 25–32℃, cooling water outlet temperature 46–60℃, cooling water flow rate 16 m³ / h. 3 / min; Cooling water specifications for the cold water base plate: Cooling water inlet temperature 25–35℃, cooling water outlet temperature 31–40℃, cooling water flow rate 12m³ / h. 3 / min; Effective current: 5.8kA; Furnace opening voltage: 38V.

5. The method for preparing a high-purity solid solution strengthened high-temperature alloy rod according to claim 1, characterized in that, In step five, the sample is heat-treated at a temperature of 1150–1200℃.

6. The method for preparing a high-purity solid solution strengthened high-temperature alloy rod according to claim 1, characterized in that, The alloy rods exhibit the following properties at room temperature: tensile strength of 770–836 MPa, yield strength of 335–390 MPa, elongation of 56–62%, reduction of area of ​​59–63%, and hardness of 178–210 HBW; tensile strength at 950°C: 208–236 MPa, yield strength of 139–191 MPa, elongation of 98–140%, and reduction of area of ​​79–95%; and high-temperature creep resistance at 950°C / 54 MPa: elongation of 59–115%.

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