A cobalt-based superalloy hs-25 hot-rolled plate and a manufacturing method thereof

Abstract

The present application relates to a kind of cobalt-based superalloy HS-25 hot-rolled plate and its manufacturing method, belong to metal processing technical field.The manufacturing method includes the following steps: non-vacuum induction smelting, Si-Ca powder and Si-Ca block are combined deoxidation, effectively reduce the oxygen content of liquid steel;Electroslag remelting, reduce Mn element burning loss by argon protection, improve composition uniformity;Forging breakdown, optimize holding time and temperature, ensure that organization is dense;Hot rolling into material, multiple back furnace insulation, improve plate thickness uniformity;Solution treatment, realize grain refinement and uniformity control by accurate heating rate and holding time.Finally, the thickness of 8mm, width of 1000mm, length of 2200mm hot-rolled plate material is obtained.The manufacturing method of the present application is optimized by process, significantly improves the comprehensive performance of plate, solves the problems such as high oxygen content, Mn burning loss is serious, grain size control is insufficient in prior art, and is suitable for high-end fields such as aviation, nuclear energy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal processing, in particular to a cobalt-based high-temperature alloy HS-25 hot-rolled plate and a manufacturing method thereof. BACKGROUND

[0002] HS-25 cobalt-based high-temperature alloy is a typical solid solution strengthening cobalt-based high-temperature alloy, which is widely used in the manufacture of key components in the fields of aviation, nuclear energy and other high-temperature and high-stress scenarios due to its excellent strength and oxidation resistance below 850°C. As a high-performance material, its plate products are usually produced by non-vacuum induction + electroslag remelting process to meet the strict requirements of high-temperature resistance, high strength and oxidation resistance.

[0003] At present, the manufacturing of HS-25 alloy plate in the prior art mainly experiences the following stages: non-vacuum induction smelting, electroslag remelting, forging breakdown, hot rolling into finished product, and subsequent solid solution heat treatment and surface treatment. Although this process route can theoretically produce plate materials that meet the application requirements, there are still the following technical difficulties and defects in actual production:

[0004] Insufficient oxygen content control leads to unstable plate performance:

[0005] HS-25 alloy does not contain traditional deoxidizing elements (such as Al, Ti, etc.), and needs to rely on external deoxidizers for deoxidization during non-vacuum induction smelting. However, traditional deoxidizers (such as Si or Ca deoxidization alone) are difficult to achieve efficient deoxidization and easy removal at the same time, which may lead to high oxygen content or residual oxide inclusions, thereby reducing the ductility and fatigue performance of the plate and affecting the long-term service life of the plate in high-temperature environments.

[0006] Control difficulty of Mn element in electroslag remelting process:

[0007] Mn is one of the key components of HS-25 alloy, and its content directly affects the strengthening effect of the alloy. However, Mn is easily affected by high temperature and oxidation conditions during electroslag remelting and is prone to burnout. The existing technology lacks a systematic control method for the burnout of Mn element, which easily leads to deviation of the composition of the plate from the design standard, especially problems in cross-section composition uniformity.

[0008] Insufficient grain size control technology:

[0009] The grain size of HS-25 alloy plate is a key factor affecting its high-temperature strength and plasticity, however, the control of grain size in the existing technology often fails to meet the requirements of strength and ductility balance at the same time. Especially in the solid solution treatment stage, the precise control of holding temperature and time is insufficient, which may lead to coarse or uneven grain size, thereby weakening the comprehensive performance of the plate.

[0010] Hot-rolled plate thickness uniformity and surface quality need to be optimized:

[0011] Hot-rolled plate stage usually involves high-temperature plastic deformation and multiple reprocessing, which may lead to poor plate thickness uniformity and even surface defects if the process parameters are not properly controlled, increasing the difficulty of subsequent processing and finishing.

[0012] The gap between plate performance testing and actual use requirements:

[0013] The HS-25 alloy plate produced in the prior art is difficult to fully meet the harsh requirements of the aerospace and nuclear energy fields in terms of high-temperature durability and oxidation resistance, especially improper grain size control will lead to unstable mechanical properties (such as endurance strength and ductility) at high temperature.

[0014] In summary, the prior art in the manufacturing process of HS-25 alloy plate faces multiple challenges such as insufficient oxygen content control, Mn element burning loss, uneven grain size, and insufficient optimization of surface quality and plate performance. These problems limit the quality consistency and performance reliability of the plate, making it difficult to meet the strict requirements of high-end application fields. Therefore, it is urgent to develop an optimized manufacturing method for cobalt-based high-temperature alloy HS-25 hot-rolled plate to effectively overcome the above technical bottlenecks and improve the overall performance and production stability of the plate. SUMMARY

[0015] The technical problem to be solved by the present application is to provide a manufacturing method for cobalt-based high-temperature alloy HS-25 hot-rolled plate to solve the problems of uneven plate composition, insufficient grain size control, and unstable performance of finished products in the conventional manufacturing method of the prior art.

[0016] In order to overcome the defects of the above prior art, the present application provides a manufacturing method for cobalt-based high-temperature alloy HS-25 hot-rolled plate, characterized in that it comprises the following steps:

[0017] S1: Non-vacuum induction smelting electrode rod;

[0018] Nickel plate, metal tungsten, metal chromium and metal cobalt are added as raw materials into a non-vacuum induction furnace, and power melting is carried out until the steel liquid temperature reaches 1520℃ or above. Si-Ca powder and Si-Ca block are used for combined deoxidation, and after deoxidation, metal manganese is added for further refining. Then, the chemical composition is analyzed by sampling, and the Mn element content is confirmed to meet the technical standard. Then, the steel liquid is poured into an ingot mold and cooled to room temperature to obtain an electrode rod;

[0019] S2: Electroslag remelting to produce steel ingot;

[0020] The electrode rod is loaded into a protective atmosphere electroslag furnace, and after filling with inert gas protection, power remelting is carried out, and after cooling treatment, an electroslag steel ingot is obtained;

[0021] S3: forging bloom;

[0022] The ingot is heated and held, and then forged into a bloom;

[0023] S4: rolling plate;

[0024] The bloom is heated and held, and then discharged and rolled into a plate;

[0025] S5: plate solution treatment;

[0026] The plate is heated and held, and then water-cooled to room temperature;

[0027] S6: plate processing treatment;

[0028] The solution-treated plate is leveled, straightened, trimmed, and surface ground to obtain a final product plate.

[0029] Compared with the prior art (related art), the manufacturing method of the cobalt-based high-temperature alloy HS-25 hot-rolled plate has the following advantages:

[0030] Precise Mn element control: During non-vacuum induction smelting, metal manganese is added after deoxidation and its content is controlled according to the upper limit to compensate for the burnout during electroslag remelting, and argon gas protection is filled during remelting to significantly reduce the oxidation and volatilization of Mn elements, making the cross-sectional Mn element distribution of the finished plate more uniform, thereby improving the strength and toughness of the finished plate;

[0031] Grain size optimization technology: By strictly controlling the heating temperature and holding time during rolling and solution treatment, the plate grain is refined and homogenized, and finally a high-quality plate with a grain size of ≤4 levels is obtained;

[0032] Improved stability of finished product performance: An optimized forging and rolling process is developed, and multi-fire forging and reheat rolling technology is adopted to effectively improve the plate thickness uniformity and internal stress distribution, significantly improving the mechanical properties and high-temperature durability of the finished plate;

[0033] Deoxidizer formula optimization: Si-Ca powder and Si-Ca block are used for combined deoxidation, with very little residual amount of CaO and SiO2 reaction, reducing harmful inclusions and improving steel purity, providing a good foundation for high-quality plate production;

[0034] Energy saving and high efficiency: Precise temperature control and energy-saving operation are adopted in each processing link to effectively reduce energy consumption and waste, improve production efficiency and yield.

[0035] The application solves the problems of uneven composition, insufficient grain size control and unstable performance of finished products in the prior art by the above-mentioned optimized process of the manufacturing method of the cobalt-based high-temperature alloy HS-25 hot-rolled plate, and provides high-temperature alloy plate materials with excellent performance for nuclear power, aviation and other fields.

[0036] In a possible implementation, in the step S1, the condition of the combined deoxidation is that the oxygen content in the molten steel is ≤30ppm.

[0037] Compared with the prior art, by controlling the oxygen content in the molten steel to ≤30ppm, the generation of oxide inclusions is reduced, and by using the combined deoxidizer (Si-Ca powder and Si-Ca block), the advantages of rapid deoxidizer reaction and easy removal of slag are fully utilized. Si reacts with oxygen to generate SiO2 which is removed by the alkaline slag, and Ca reacts with oxygen to generate CaO which is easily removed from the molten steel due to its extremely low solubility, and the two reactions work together to effectively reduce the residual oxygen content in the molten steel.

[0038] In a possible implementation, in the step S1, the time of the continued refining is 15 minutes.

[0039] Compared with the prior art, by setting the continued refining time to 15 minutes, it is ensured that the key elements (Mn, Cr, W) in the molten steel after deoxidation are fully and uniformly distributed, and the residual impurities (such as oxygen, nitrogen, etc.) are further removed. This time range takes into account the sufficiency of the refining reaction and the operation efficiency, avoids incomplete deoxidation caused by insufficient time or loss of key elements such as Mn due to excessive time, and further optimizes the chemical composition and purity control of the molten steel; under the premise of stable Mn content, the uniformity of the composition distribution of the molten steel and the strict control of the oxygen content are realized, which lays a good foundation for subsequent electroslag remelting and forging breakdown. The comprehensive performance of the finished hot-rolled plate, including grain size, oxidation resistance and high-temperature durability, is improved, and the risk of composition segregation and unstable quality is significantly reduced.

[0040] In a possible implementation, in the step S2, the inert gas is argon.

[0041] Compared with the prior art, by filling argon in the electroslag remelting process, the composition consistency and purity of the molten steel in the melting process are effectively improved, and the problems of fluctuation of Mn and Cr content caused by oxidation and volatilization are avoided. The electroslag ingot produced finally is more uniform in cross-sectional composition distribution and has more refined grain structure, which provides a high-quality material basis for subsequent forging and rolling. The mechanical properties, high-temperature resistance and grain size of the finished hot-rolled plate meet or exceed the technical standard requirements, and the quality stability and service life of the product are significantly improved.

[0042] In a possible implementation, in the step S3, the charging temperature of the ingot is less than 600°C, the heating time is 5 hours, the holding temperature is 1180±10°C, and the holding time is greater than 4 hours.

[0043] Compared with the prior art, by adopting the technical scheme, controlling the charging temperature of the ingot to be less than 600°C can effectively reduce thermal shock caused by excessive temperature difference, and avoid problems such as surface cracking and internal stress concentration of the ingot; the heating time of 5 hours ensures slow heating of the ingot from outside to inside, reduces the temperature gradient, thereby reducing the phenomenon of excessive temperature difference between the surface and the core caused by rapid heating, and improves the heating uniformity; the holding temperature of 1180±10°C is the best forging temperature of the alloy, which can promote the homogenization of the internal structure of the ingot; and the holding time greater than 4 hours ensures that the core of the ingot completely reaches the required temperature, thereby providing stable temperature conditions for subsequent forging; by optimizing the charging temperature, heating time and holding conditions of the ingot, sufficient homogenization treatment of the ingot before forging is realized, and problems such as internal stress and temperature difference defects are reduced. The finally forged slab is significantly better than the traditional process in terms of size precision, structure uniformity and grain refinement, and provides a high-quality raw material basis for subsequent rolling and processing. The mechanical properties and high-temperature stability of the finished hot-rolled plate meet or even exceed the technical standards, and the reliability and service life of the product are significantly improved.

[0044] In a possible implementation, in the step S3, the forging adopts a direct elongation process, and the slab is obtained through multi-fire forging, and the slab is air-cooled to room temperature after the forging is completed.

[0045] Compared with the prior art, by adopting the technical scheme, through the comprehensive process of adopting the direct elongation process, multi-fire forging and air-cooling treatment, the size precision control and structure performance optimization of the slab are successfully realized, and problems such as structure coarsening and residual stress caused by complex forging path or improper forging method in the prior art are solved. The finally produced slab provides a high-quality raw material basis for subsequent rolling, ensures that the hot-rolled plate meets or even exceeds the technical standards in terms of mechanical properties, size stability and high-temperature environment applicability, and significantly improves the industrial application value of the product.

[0046] In a possible implementation, in the step S4, the charging temperature of the slab is less than 600°C, the heating time is 3 hours, the holding temperature is 1180±10°C, and the holding time is greater than 1 hour.

[0047] Compared with the prior art, by adopting the technical scheme, by optimizing the charging temperature of the slab, the heating time and the holding condition, sufficient preheating and microstructure optimization treatment of the slab before rolling are realized, the deformation uniformity and the processing performance of the slab in the rolling process are significantly improved, the hot-rolled plate finally rolled is significantly better than the traditional process in grain refinement, mechanical property stability and dimensional accuracy, meets or even exceeds the technical standard, and provides high-quality basic materials for high-end applications in the fields of aviation, nuclear power and the like.

[0048] In a possible implementation manner, in the step S5, the charging temperature of the slab is less than 600 DEG C, the heating speed is less than or equal to 150 DEG C / h, the holding temperature is 1190 DEG C ± 10 DEG C, and the holding time is greater than 1 h.

[0049] Compared with the prior art, by adopting the technical scheme, the setting of the heating speed less than or equal to 150 DEG C / h ensures the uniformity of the overall temperature rise of the slab, effectively reduces the problem of inconsistent internal and external microstructure caused by temperature difference, and avoids the generation of grain coarsening and micro-cracks, the holding temperature 1190 DEG C ± 10 DEG C is the best solid solution temperature of the alloy, can promote the strengthening elements (such as Cr and W) to be fully solid-solved in the matrix, optimize the distribution of the strengthening phase, and improve the high-temperature strength and oxidation resistance of the alloy, and the holding time greater than 1 h ensures the microstructure homogenization in the whole cross section of the slab, further reduces the possible composition segregation and grain boundary impurity accumulation phenomenon, and enhances the service performance of the material.

[0050] Another technical problem to be solved by the present application is to provide a hot-rolled plate of a cobalt-based high-temperature alloy HS-25, so as to solve the problems of coarse grains, unstable mechanical properties and poor processing adaptability of the conventional HS-25 alloy plate in the prior art.

[0051] In order to overcome the defects of the prior art, the present application provides a HS-25 cobalt-based high-temperature alloy, which is prepared by the above preparation method, and the chemical composition of the alloy is: C: 0.05%-0.15%, Si: ≤1.0%, Mn: 1.0%-2.0%, S: ≤0.03%, P: ≤0.03%, Cr: 19.0%-21.0%, Ni: 9.0%-11.0%, W: 14.0%-16.0%, Fe: ≤3.0%, and the balance is Co and other inevitable impurities.

[0052] Compared with the prior art (related art) of the cobalt-based high-temperature alloy HS-25 hot-rolled plate, the cobalt-based high-temperature alloy HS-25 hot-rolled plate has the following advantages: the cobalt-based high-temperature alloy HS-25 hot-rolled plate of the present application ensures that the strengthening phase in the alloy is fully solid-solved and uniformly distributed by controlling the solid-solution temperature and holding time, significantly improves the high-temperature performance and service stability of the plate, and realizes significant grain refinement and homogenization by combining precise heating and holding processes, effectively improves the mechanical property stability of the plate, especially the high-temperature creep resistance, through the above composition control and manufacturing process optimization, including Cr (19.0%-21.0%) and W (14.0%-16.0%) in the alloy to provide excellent oxidation resistance and high-temperature strength, and by precisely controlling the composition ratio, grain coarsening and uneven distribution of precipitates are avoided, the content of S and P is strictly controlled to be ≤0.03%, effectively reducing the crack sensitivity, significantly improving the ductility and processability of the alloy, especially suitable for high-temperature forming and subsequent processing, by precisely controlling the Mn content (1.0%-2.0%), the stability and fatigue resistance of the alloy in a high-temperature environment are enhanced, and the toughness of the material is improved, the HS-25 cobalt-based high-temperature alloy of the present application successfully solves the problems of grain coarsening, composition unevenness, mechanical property fluctuation and the like of the traditional HS-25 alloy plate, and finally realizes the overall improvement of high-temperature strength, oxidation resistance and ductility. At the same time, the processability of the hot-rolled plate of the present application is significantly improved, meeting the stringent requirements of high-end fields such as aviation and nuclear power for high-temperature materials.

[0053] In one possible implementation, the chemical composition of the alloy is: C: 0.066%, Si: 0.12%, Mn: 1.91%, S: 0.002%, P: 0.004%, Cr: 20.08%, Ni: 10.01%, W: 15.02%, Fe: 0.32%, and the balance is Co and other unavoidable impurities.

[0054] Compared with the prior art, the further optimization of the contents of C, Cr and W strengthens the base structure and avoids the brittleness problem caused by too high C content, ensuring the balance between high temperature strength and ductility of the alloy. In particular, the combination of Cr (20.08%) and W (15.02%) provides excellent oxidation resistance and high temperature creep resistance. By controlling the contents of S and P to extremely low levels of 0.002% and 0.004% respectively, the crack sensitivity and grain boundary segregation problems are effectively avoided, and the toughness and service life of the alloy are significantly improved, especially in high temperature environment. The upper limit control of the content of Mn (1.91%) enhances the fatigue resistance and high temperature stability of the material, and reduces the hardening effect during processing, providing ideal operability for subsequent hot rolling and forming processing. The precise ratio of Ni and Fe enhances the toughness and processing performance of the alloy, which helps to obtain a more uniform microstructure, further improving the oxidation resistance and service life of the plate. Through the above improvements, the HS-25 cobalt-based high-temperature alloy of the present embodiment not only has significant advantages in high temperature strength, creep resistance and oxidation resistance, but also achieves breakthroughs in ductility, processability and service stability, further meeting the application requirements of high-end fields such as aviation and nuclear power. DETAILED DESCRIPTION

[0055] First of all, those skilled in the art should understand that these embodiments are only used to explain the technical principles of the embodiments of the present application, and are not intended to limit the protection scope of the embodiments of the present application. Those skilled in the art can adjust them as needed to adapt to specific application occasions.

[0056] The present application provides a manufacturing method of cobalt-based high-temperature alloy HS-25 hot-rolled plate, comprising the following steps:

[0057] S1: non-vacuum induction smelting electrode rod;

[0058] Nickel plate, metal tungsten, metal chromium and metal cobalt are added as raw materials into a non-vacuum induction furnace, and power melting is performed until the steel liquid temperature reaches 1520℃ or above. Si-Ca powder and Si-Ca block are used for combined deoxidation, and after deoxidation is completed, metal manganese is added for further refining. Then, the chemical composition is analyzed by sampling, and after confirming that the content of Mn element meets the technical standard, the steel liquid is poured into an ingot mold and cooled to room temperature to obtain an electrode rod;

[0059] S2: electroslag remelting production of steel ingot;

[0060] The electrode rod is loaded into a protective atmosphere electroslag furnace, and after inert gas protection, power remelting is performed, and after cooling treatment, an electroslag steel ingot is obtained;

[0061] S3: forging and breaking down;

[0062] heating and holding the ingot and then forging the ingot into a slab;

[0063] S4: rolling the slab;

[0064] heating and holding the slab and then hot rolling the slab out of the furnace to form a plate;

[0065] S5: solution treatment of the plate;

[0066] heating and holding the plate and then water cooling the plate to room temperature;

[0067] S6: processing treatment of the plate;

[0068] the solution-treated plate is subjected to skin pass, straightening, edge cutting and surface grinding to obtain a final product plate.

[0069] The manufacturing method of the present application, at the initial design stage, takes into account the following technical difficulties existing in the prior art:

[0070] 1. Non-vacuum smelting deoxidation of HS-25 alloy. Since HS-25 does not contain deoxidizing elements, the key point of the non-vacuum induction furnace smelting process is to select appropriate deoxidizers. After adding such deoxidizers to the molten steel, they will chemically react with oxygen and be easily removed from the molten steel, and cannot chemically react with other elements in the molten steel to form other compounds, which will have a harmful effect on the final performance of the product.

[0071] 2. Control of Mn element in the range of medium limit in electroslag remelting. It is required to master the burn-off law of Mn element in the electroslag process, and control the Mn element in the process requirement range in the non-vacuum induction, so as to control the content of Mn element.

[0072] 3. Product plate grain size control technology. Selecting appropriate solution holding temperature and holding time is the key technology to obtain ideal grain size.

[0073] Based on the above technical difficulties, the present application provides a manufacturing method of cobalt-based high-temperature alloy HS-25 hot-rolled plate, which comprises the following steps:

[0074] Non-vacuum induction smelting electrode rod: the metal raw material is loaded into a non-vacuum induction furnace, after high-temperature melting, Si-Ca powder and Si-Ca block are used for combined deoxidation, Si and oxygen react to generate SiO2 which is easily absorbed and removed by slag (alkaline slag), oxygen and Ca easily react to generate CaO, and the solubility of Ca in molten steel is very small, Ca and CaO are not easy to remain in the molten steel, which has good deoxidation effect, after 3-4 batches of deoxidation, the chemical composition and oxygen content of the HS-25 molten steel are sampled and analyzed, and the results meet the process requirements.

[0075] As a preferred scheme, in the step S1, the combined deoxidization conditions are: deoxidizing the oxygen content in the molten steel to ≤30ppm.

[0076] As a preferred scheme, in the step S1, the time for the continuous refining is 15 minutes.

[0077] As a preferred scheme, in the step S2, the inert gas is argon.

[0078] As a preferred scheme, in the step S3, the charging temperature of the ingot is less than 600℃, the heating time is 5 hours, the holding temperature is 1180±10℃, and the holding time is greater than 4 hours.

[0079] As a preferred scheme, in the step S3, the forging adopts a direct elongation process, and the slab is obtained through multi-fire forging, and the slab is air-cooled to room temperature after the forging is completed.

[0080] As a preferred scheme, in the step S4, the charging temperature of the slab is less than 600℃, the heating time is 3 hours, the holding temperature is 1180±10℃, and the holding time is greater than 1 hour.

[0081] As a preferred scheme, in the step S5, the charging temperature of the plate is less than 600℃, the heating speed is less than or equal to 150℃ / hour, the holding temperature is 1190±10℃, and the holding time is greater than 1 hour.

[0082] The application also provides a HS-25 cobalt-based high-temperature alloy, which is prepared by the above preparation method, and the chemical composition of the alloy is: C: 0.05%-0.15%, Si: ≤1.0%, Mn: 1.0%-2.0%, S: ≤0.03%, P: ≤0.03%, Cr: 19.0%-21.0%, Ni: 9.0%-11.0%, W: 14.0%-16.0%, Fe: ≤3.0%, and the balance is Co and other inevitable impurities.

[0083] As a preferred scheme, the chemical composition of the alloy is: C: 0.066%, Si: 0.12%, Mn: 1.91%, S: 0.002%, P: 0.004%, Cr: 20.08%, Ni: 10.01%, W: 15.02%, Fe: 0.32%, and the balance is Co and other inevitable impurities.

[0084] The above-mentioned range of technical solutions of the application will be further explained and described in combination with specific data as follows:

[0085] Example 1

[0086] The present embodiment provides a cobalt-based high-temperature alloy HS-25 hot-rolled plate and a manufacturing method thereof, and the chemical composition of the HS-25 cobalt-based high-temperature alloy is:

[0087] C: 0.05%, Si: 0.15%, Mn: 1.0%, S: 0.02%, P: 0.01%, Cr: 19.0%, Ni: 9.0%, W: 14.0%, Fe: 2.5%, balance Co and other inevitable impurities.

[0088] The manufacturing method steps are as follows:

[0089] S1: Non-vacuum induction smelting electrode rod

[0090] Nickel plate, metal tungsten, metal chromium and metal cobalt are added as raw materials into a non-vacuum induction furnace, and power heating is performed to reach a steel liquid temperature of 1520°C; Si-Ca powder and Si-Ca block are used for combined deoxidation, and after 3 batches of deoxidation operation, the oxygen content is reduced to 25 ppm; after deoxidation is completed, metal manganese is added for refining, and the refining time is 15 minutes. After sampling and analyzing the chemical composition, it is confirmed that the content of Mn element is 1.0%, and then the steel liquid is poured into a Φ360mm ingot mold, the mold cooling time is 2 hours, and after demolding, air cooling is performed to room temperature to obtain an electrode rod.

[0091] S2: Electroslag remelting production of steel ingot

[0092] The electrode rod is loaded into a protective atmosphere electroslag furnace, and argon is filled for 5 minutes before power feeding to remove air; during the remelting process, the argon pressure is maintained at 2000Pa, and after cooling, a Φ420mm electroslag steel ingot is obtained. The analysis results of the head and tail samples of the steel ingot show that the content of Mn element is 1.0%, and the composition is uniform.

[0093] S3: Forging and blooming

[0094] The steel ingot is loaded into the furnace, the loading temperature is 550°C, the heating time is 5 hours, the holding temperature is 1170°C, and the holding time is 4 hours. After the holding is completed, the furnace is discharged, and through a multi-fire direct elongation process, a 60×340×Lmm size slab is forged, and after the forging is completed, the slab is air cooled to room temperature.

[0095] S4: Rolling plate

[0096] The above slab is loaded into the furnace, the loading temperature is 550°C, the heating time is 3 hours, the holding temperature is 1170°C, and the holding time is 1 hour. After discharge, a 20mm thick slab is rolled. After the slab is reheated and held for 1 hour, it is discharged and rolled into a 8.5×1020×2500mm size plate.

[0097] S5: Solid solution treatment of plate

[0098] The above plate is loaded into an electric heating furnace, the loading temperature is 550°C, and the temperature is raised to 1170°C at a rate of 150°C / hour, and after holding for 1 hour, the furnace is discharged and water cooled to room temperature.

[0099] S6: Plate processing

[0100] The plate after the above solid solution treatment is flattened, straightened, trimmed and surface ground to obtain a finished plate of 8x1000x2200mm specification.

[0101] Example 2

[0102] The present embodiment provides a cobalt-based high-temperature alloy HS-25 hot-rolled plate and a manufacturing method thereof, the chemical composition of the HS-25 cobalt-based high-temperature alloy is:

[0103] C: 0.15%, Si: 1.0%, Mn: 2.0%, S: 0.03%, P: 0.03%, Cr: 21.0%, Ni: 11.0%, W: 16.0%, Fe: 3.0%, the balance being Co and other inevitable impurities.

[0104] The manufacturing method steps are as follows:

[0105] S1: Non-vacuum induction smelting electrode rod

[0106] Nickel plate, metal tungsten, metal chromium and metal cobalt are added as raw materials into a non-vacuum induction furnace, and power heating is performed to a steel liquid temperature of 1520℃; Si-Ca powder and Si-Ca block are used for combined deoxidation, and the oxygen content is reduced to 22ppm through 4 batches of deoxidation operation; after deoxidation is completed, metal manganese is added for refining, and the refining time is 18 minutes. After sampling and analyzing the chemical composition, it is confirmed that the content of Mn element is 2.0%, and then the steel liquid is poured into a Φ360mm ingot mold, the mold cooling time is 2 hours, and after demolding, it is air cooled to room temperature to obtain an electrode rod.

[0107] S2: Electroslag remelting production of steel ingot

[0108] The electrode rod is loaded into a protective atmosphere electroslag furnace, and argon is filled for 5 minutes before power feeding to exclude air; the argon pressure is maintained at 2500Pa during the remelting process, and a Φ420mm electroslag steel ingot is obtained after cooling. The sample analysis results of the head and tail of the steel ingot show that the content of Mn element is 2.0%, and the composition is uniform.

[0109] S3: Forging and breaking down

[0110] The steel ingot is loaded into the furnace, the loading temperature is 550℃, the heating time is 5 hours, the holding temperature is 1180℃, and the holding time is 4 hours. After the holding is completed, the furnace is discharged, and a plate blank of 60x340xLmm specification is forged by a multi-fire direct elongation process, and the plate blank is air cooled to room temperature after forging is completed.

[0111] S4: Rolling plate

[0112] The slab is charged into the furnace at a temperature of 550°C, heated for 3 hours, and held at a temperature of 1180°C for 1.5 hours. The slab is discharged and rolled into a 20mm thick plate. The plate is reheated and held for 1 hour, then discharged and rolled into a 8.5x1020x2500mm plate.

[0113] S5: Solution treatment of the plate

[0114] The plate is charged into an electric heating furnace at a temperature of 550°C, heated to 1180°C at a rate of 150°C / hour, and held for 1.5 hours, then discharged and water-cooled to room temperature.

[0115] S6: Processing of the plate

[0116] The solution-treated plate is flattened, straightened, trimmed, and surface ground, and finally a 8x1000x2200mm finished plate is obtained.

[0117] Example 3

[0118] This example provides a cobalt-based high-temperature alloy HS-25 hot-rolled plate and a manufacturing method thereof, the chemical composition of the HS-25 cobalt-based high-temperature alloy is:

[0119] C: 0.066%, Si: 0.12%, Mn: 1.91%, S: 0.002%, P: 0.004%, Cr: 20.08%, Ni: 10.01%, W: 15.02%, Fe: 0.32%, and the balance is Co and other unavoidable impurities.

[0120] The manufacturing method steps are as follows:

[0121] S1: Non-vacuum induction smelting electrode rod

[0122] Nickel plate, metal tungsten, metal chromium, and metal cobalt are added as raw materials into a non-vacuum induction furnace, and are heated by electric power to a steel liquid temperature of 1520°C; Si-Ca powder and Si-Ca block are used for combined deoxidation, and the oxygen content is reduced to 20ppm through 3 batches of deoxidation operation; after deoxidation is completed, metal manganese is added for refining, and the refining time is 18 minutes. After sampling and analyzing the chemical composition, it is confirmed that the content of Mn element is 1.91%, the steel liquid is poured into a Φ360mm ingot mold, the mold cooling time is 1.5 hours, and after demolding, it is air-cooled to room temperature to obtain an electrode rod.

[0123] S2: Electroslag remelting production of steel ingot

[0124] The electrode rod is loaded into a protective atmosphere electroslag furnace, and argon is filled for 5 minutes before power transmission to remove air; the argon pressure is maintained at 3000 Pa during the remelting process, and a Φ420 mm electroslag steel ingot is obtained after cooling. The analysis results of the head and tail samples of the steel ingot show that the content of Mn element is 1.91%, and the composition is uniform.

[0125] S3: forging breakdown

[0126] The steel ingot is loaded into the furnace, the loading temperature is 550°C, the heating time is 5 hours, the holding temperature is 1190°C, and the holding time is 4 hours. After the holding is completed, the furnace is discharged, and the slab is forged into a 60*340*L mm size slab through a multi-fire direct elongation process, and the slab is air cooled to room temperature after forging.

[0127] S4: rolling plate

[0128] The above slab is loaded into the furnace, the loading temperature is 550°C, the heating time is 3 hours, the holding temperature is 1190°C, and the holding time is 1 hour. The furnace is discharged and rolled into a 20 mm thick slab. The slab is reheated and held for 30 minutes, and then discharged and rolled into a 8.5*1020*2500 mm size plate.

[0129] S5: solution treatment of plate

[0130] The above plate is loaded into an electric heating furnace, the loading temperature is 550°C, and the temperature is heated to 1190°C at a rate of 150°C / hour, and then held for 2 hours before being discharged and water cooled to room temperature.

[0131] S6: plate processing

[0132] The above solution treated plate is flattened, straightened, trimmed and surface ground, and finally an 8*1000*2200 mm size finished plate is obtained.

[0133] The chemical composition control results of the steel ingot obtained after the electroslag remelting step of the above embodiment 3 are as follows:

[0134] Table 1:

[0135]

[0136] The finished plate prepared after step S6 is continuously detected, 2 pieces of 40*300 mm samples are cut in the width direction of the plate, and room temperature tensile properties, room temperature hardness HV, grain size, and high temperature durability are measured, all of which meet the technical requirements, and the results are as follows:

[0137] Table 2:

[0138]

[0139] Table 1 shows the chemical composition results of the steel ingot after electroslag remelting, wherein the contents of key elements such as Mn, Cr and W at the head and tail of the steel ingot meet the requirements of the technical standard, and the composition distribution is uniform. This shows that the present application successfully solves the problem of uneven composition caused by Mn element burning loss in the prior art by the non-vacuum induction smelting and electroslag remelting process, and significantly improves the composition consistency of the material.

[0140] Table 2 provides the final plate performance data of Example 3. The measured results show that the room temperature tensile properties (tensile strength 1035 MPa, yield strength 492 MPa) of the plate, the grain size (6 levels) and the high temperature endurance performance (145 MPa endurance time 67 hours) all meet or even exceed the requirements of the technical index. This further verifies that by optimizing the forging, rolling and solid solution treatment process, the grain is significantly refined, and the strength and high temperature performance of the plate are comprehensively improved.

[0141] Through the above examples, it is further proved that the present application provides a cobalt-based high-temperature alloy HS-25 hot-rolled plate and a manufacturing method thereof, which solves the following key technical problems commonly encountered in the manufacturing of cobalt-based high-temperature alloy HS-25 hot-rolled plates in the prior art:

[0142] Insufficient oxygen content control leads to unstable performance: the manufacturing method of the present application reduces the oxygen content to below 30 ppm by using Si-Ca powder and Si-Ca block combined deoxidation, effectively reduces the generation of oxidized inclusions, and significantly improves the purity and ductility of the material.

[0143] Mn element burning loss control difficulty: the manufacturing method of the present application introduces inert gas argon protection during electroslag remelting, successfully inhibits the volatilization of Mn under high temperature conditions, and ensures the cross-section composition uniformity.

[0144] Grain size unevenness leads to performance decline: the manufacturing method of the present application optimizes the heating speed and holding time of solid solution treatment, ensures the refinement and homogenization of the grain, and solves the problems of grain coarsening and performance fluctuation.

[0145] Poor plate thickness and surface quality: the manufacturing method of the present application adopts multiple re-melting holding and rolling processes and surface finishing processes, effectively improves the thickness uniformity and surface finish of the plate.

[0146] Technical principle:

[0147] The manufacturing method of the present application precisely controls the oxygen content and the addition amount of Mn element in the non-vacuum induction smelting stage, ensures the stability of the molten steel composition; through the synergistic deoxidation reaction of Si and Ca (generating easy-to-remove SiO2 and CaO), the deoxidation efficiency is significantly improved, and the residual inclusions are reduced;

[0148] In the electroslag remelting stage, the content of Mn and other volatile elements is further stabilized by introducing argon to reduce the oxidation reaction and reduce the volatilization rate, ensuring the uniformity of the composition and the compliance of the technical standard.

[0149] In the forging and rolling process, by strictly controlling the holding temperature and time, the consistency of the internal and external temperature of the blank and the uniformity of deformation are ensured, so that the grain structure and material strength are optimized.

[0150] In the solid solution treatment stage, by adjusting the heating rate and holding time, the strengthening elements Cr and W are fully solid-solved and uniformly distributed in the matrix, significantly improving the high temperature strength and oxidation resistance.

[0151] Summary:

[0152] The manufacturing method of the cobalt-based high-temperature alloy HS-25 hot-rolled plate of the application successfully solves the technical bottlenecks of insufficient oxygen content control, Mn element burning loss and grain coarsening in the prior art by comprehensively optimizing the smelting, forging, rolling and heat treatment processes. The prepared cobalt-based high-temperature alloy HS-25 hot-rolled plate not only has uniform composition and refined grains, but also significantly outperforms the technical standard in terms of room temperature tensile properties and high temperature endurance properties, providing a high-quality material solution for the application of high-end fields such as aviation and nuclear power.

[0153] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "in this embodiment", "specific examples" or "some examples" means that the specific features, mechanisms, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, mechanisms, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. Furthermore, the skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction.

[0154] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method of manufacturing a hot-rolled plate of a cobalt-based superalloy HS-25, characterized by, The method comprises the following steps: S1: non-vacuum induction smelting electrode rod; nickel plate, metal tungsten, metal chromium and metal cobalt are added as raw materials into a non-vacuum induction furnace, power is supplied to melt to an alloy liquid temperature of 1520 DEG C or above, Si-Ca powder and Si-Ca block are combined to deoxidize, after deoxidization, metal manganese is added for further refining, then sampling analysis of chemical components is carried out, after confirming that the content of Mn element meets the technical standard, the alloy liquid is poured into an ingot mold, and cooled to room temperature to obtain an electrode rod; S2: electroslag remelting to produce an alloy ingot; the electrode rod is loaded into a protective atmosphere electroslag furnace, inert gas protection is carried out, power is supplied to remelt, and after cooling treatment, an electroslag alloy ingot is obtained; S3: forging and blooming; the alloy ingot is heated and kept warm, and then is forged into a slab; S4: rolling plate; the slab is heated and kept warm, and then is discharged from the furnace and rolled into a plate; S5: solid solution treatment of the plate; the plate is heated and kept warm, and then is water cooled to room temperature; S6: processing treatment of the plate; the plate after the solid solution treatment is flattened, straightened, trimmed and surface ground, and finally a finished plate is obtained; In the step S3, the loading temperature of the alloy ingot is less than 600 DEG C, the heating time is 5 hours, the keeping warm temperature is 1180 DEG C plus or minus 10 DEG C, and the keeping warm time is greater than 4 hours; In the step S3, the forging adopts a direct elongation process, and the slab is obtained through multiple times of forging, and the slab is air cooled to room temperature after the forging is completed; In the step S4, the loading temperature of the slab is less than 600 DEG C, the heating time is 3 hours, the keeping warm temperature is 1180 DEG C plus or minus 10 DEG C, and the keeping warm time is greater than 1 hour; In the step S5, the loading temperature of the plate is less than 600 DEG C, the heating speed is less than or equal to 150 DEG C / hour, the keeping warm temperature is 1190 DEG C plus or minus 10 DEG C, and the keeping warm time is greater than 1 hour; The chemical components of the cobalt-based high-temperature alloy HS-25 hot-rolled plate are as follows: C: 0.05%-0.15%, Si: ≤1.0%, Mn: 1.0%-2.0%, S: ≤0.03%, P: ≤0.03%, Cr: 19.0%-21.0%, Ni: 9.0%-11.0%, W: 14.0%-16.0%, Fe: ≤3.0%, and the balance is Co and other inevitable impurities.

2. The method of producing a hot-rolled plate of Co-based superalloy HS-25 according to claim 1, characterized in that, In the step S1, the conditions of the combined deoxidization are as follows: the oxygen content in the alloy liquid is ≤30ppm after deoxidization.

3. The method of producing a hot-rolled plate of Co-based superalloy HS-25 according to claim 1, characterized in that, In the step S1, the time of the further refining is 15 minutes.

4. The method of producing a hot-rolled plate of Co-based superalloy HS-25 according to claim 1, characterized by, In the step S2, the inert gas is argon.

5. The method of producing a hot-rolled plate of Co-based superalloy HS-25 according to claim 1, characterized by, The chemical components of the cobalt-based high-temperature alloy HS-25 hot-rolled plate are as follows: C: 0.066%, Si: 0.12%, Mn: 1.91%, S: 0.002%, P: 0.004%, Cr: 20.08%, Ni: 10.01%, W: 15.02%, Fe: 0.32%, and the balance is Co and other inevitable impurities.

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