HS-25 cobalt-based high-temperature alloy cold-drawn material and manufacturing method thereof

Abstract

The invention relates to an HS-25 cobalt-based high-temperature alloy cold-drawn material and a manufacturing method thereof, and belongs to the field of metal processing. The alloy comprises the following components in percentage by weight: 0.04%-0.06% of C, 0.15%-0.20% of Si, 1.60%-1.70% of Mn, less than or equal to 0.003% of S, less than or equal to 0.01% of P, 19.90%-20.00% of Cr, 10.00%-10.10% of Ni, 14.80%-14.90% of W, 1.20%-1.30% of Fe and the balance of Co and other inevitable impurities. The manufacturing method comprises the following steps: producing steel ingots through vacuum induction smelting and electroslag remelting, heating and forging the steel ingots into square billets, reheating and rolling the square billets into round bars; carrying out solution treatment on the round bar at 1190 DEG C, polishing or turning the surface, and carrying out cold drawing to obtain a material; and the cold-drawn material is subjected to destressing treatment through induction heating. Under the condition that the cold drawing deformation is controlled to be 17%-21%, the comprehensive performance of the cold drawing material is remarkably improved, and test results show that the hardness HRC of the cold drawing material is 35-40, the percentage elongation after fracture is larger than or equal to 25%, the percentage reduction of area is larger than or equal to 30%, and the technical standard of the nuclear power field is met. The manufacturing method is optimized in process, excellent in performance and suitable for manufacturing nuclear power parts and other high-temperature and high-stress parts.

Description

Technical Field

[0001] The present invention relates to the technical field of metal processing, and in particular to an HS-25 cobalt-based high-temperature alloy cold-drawn material and a manufacturing method thereof. Background Art

[0002] HS-25, a solid-solution-strengthened cobalt-based superalloy, is widely used in high-temperature components such as aerospace engine guide vanes, turbine outer rings, vortex finders, and seals due to its excellent strength and oxidation resistance below 850°C. It even exhibits excellent heat resistance in air at 1090°C. In recent years, cold-drawn materials of this alloy have been increasingly used in the nuclear power industry for the manufacture of high-temperature, high-stress components. However, in actual production and use, existing technologies still face the following major challenges:

[0003] Work hardening problems:

[0004] During the cold drawing process of HS-25 alloy, work hardening occurs within the metal's internal structure, leading to a mismatch in material properties. In particular, it's difficult to achieve both the required hardness and the desired elongation and reduction of area. Existing cold drawing processes typically cannot simultaneously meet these mechanical performance targets. In particular, when the cold drawing deformation is large, the hardness improves while the elongation and reduction decrease significantly, making it difficult to meet the technical standards for the nuclear power industry.

[0005] Process control complexity:

[0006] Existing processes typically produce HS-25 alloy ingots using vacuum induction and electroslag remelting, followed by forging and cold drawing to produce cold-drawn steel. However, these traditional methods involve multiple heating and cooling operations during production, resulting in complex and energy-intensive processes. Process conditions, particularly during the forging, rolling, and cold-drawing stages, significantly impact material properties, and even the slightest inaccuracy can result in substandard products.

[0007] Insufficient optimization of mechanical properties:

[0008] Conventional cold drawing processes create a conflict between the hardness and elongation of cold-drawn materials. Increasing hardness often comes at the expense of ductility. Because the nuclear power industry places extremely high demands on the mechanical properties of cold-drawn materials, existing processes struggle to achieve both high hardness and sufficient ductility and shrinkage, limiting the material's practical applications.

[0009] Stress relief process defects:

[0010] Cold-drawn materials generate significant residual stress during the drawing process. Without proper stress relief, these products are prone to failure during use due to stress concentration. Existing annealing or stress relief methods often suffer from a narrow temperature range and long processing times, making it difficult to achieve uniform stress relief.

[0011] In summary, existing technologies for manufacturing HS-25 alloy cold-drawn materials suffer from severe work hardening, mismatched mechanical properties, complex processes, and incomplete stress relief, directly impacting product quality and the reliability of industrial applications. Therefore, there is an urgent need to develop an optimized cold-drawing process and stress relief method to produce HS-25 cold-drawn materials with mechanical properties that fully meet standard requirements and enhance their applicability in the nuclear power sector. Summary of the Invention

[0012] The technical problem to be solved by the present invention is to provide a HS-25 cobalt-based high-temperature alloy cold-drawn material to solve the problems of mechanical property mismatch, insufficient hardness, poor ductility and residual processing stress in conventional cold-drawn materials in the prior art.

[0013] In order to overcome the defects of the above-mentioned prior art, the present invention provides a HS-25 cobalt-based high-temperature alloy cold-drawn material, the chemical composition of the cold-drawn material being: C: 0.04%-0.06%, Si: 0.15%-0.20%, Mn: 1.60%-1.70%, S: ≤0.003%, P: ≤0.01%, Cr: 19.90%-20.00%, Ni: 10.00%-10.10%, W: 14.80%-14.90%, Fe: 1.20%-1.30%, and the balance being Co and other inevitable impurities.

[0014] Compared with the existing technology (related technology), the HS-25 cobalt-based high-temperature alloy cold-drawn material of the present application has the following advantages: the composition of conventional cold-drawn materials is relatively wide, resulting in insufficient hardness after cold-drawing deformation, which is difficult to meet the use requirements in high-temperature and high-stress environments. However, the present invention strictly controls the content range of strengthening elements (such as Cr and W) in the alloy and optimizes the carbon (C) content. The hardness of the cold-drawn material can be effectively improved after cold drawing, and the hardness HRC is stabilized between 35-40, thereby significantly improving the load-bearing capacity and high-temperature resistance of the cold-drawn material in the nuclear power field. By controlling the sulfur (S) content to ≤0.003% and the phosphorus (P) content to ≤0.01%, the The risk of processing cracks is reduced, while processing performance and ductility are optimized. In the prior art, conventional cold-drawn materials have too low a deformation amount to significantly improve hardness, while too high a deformation amount leads to severe work hardening and a significant decrease in ductility. In addition, the residual stress in the material is high, which may cause stress concentration, deformation, and even failure of the product during service. The cold-drawn material of the present invention directly affects the hardness and strength of the material through an optimized component ratio (C, Cr, W), and improves the ductility and toughness through strictly controlled impurity content (S, P), ultimately successfully achieving a balance among the three major indicators of hardness, elongation after fracture, and cross-sectional shrinkage, meeting the stringent requirements of high-tech fields such as nuclear power and aviation.

[0015] In one possible embodiment, the chemical composition of the cold-drawn material is: C: 0.05%, Si: 0.19%, Mn: 1.68%, S: 0.0022%, P: 0.008%, Cr: 19.93%, 10.03%, Ni: 14.82%, Fe: 1.28%, and the balance is Co.

[0016] Compared with the existing technology, the above technical scheme is adopted to further optimize the chemical composition of cold-drawn materials. Controlling the appropriate carbon content can strengthen the alloy matrix while avoiding the brittleness problem caused by excessive carbon content, so that the cold-drawn materials can achieve a balance between high hardness and high ductility. The extremely low sulfur and phosphorus content significantly reduces the risk of cracks during processing and use, and improves the toughness and ductility of the material. The high content of chromium and tungsten provides excellent corrosion resistance and high-temperature strength, while ensuring that the material still maintains good dimensional stability under high temperature conditions. The stabilizing effect of nickel improves the oxidation resistance, and the appropriate amount of iron improves the processing performance of the material. The further optimized formula makes the cold-drawn material have better comprehensive performance.

[0017] In a possible implementation manner, the hardness HRC of the cold-drawn material is 35-40, the elongation after fracture is ≥25%, and the cross-sectional shrinkage is ≥30%.

[0018] Compared with the prior art, the present invention achieves an optimal balance between high hardness and high ductility through precise control of cold drawing deformation and stress relief treatment, so that the cold-drawn material has both high strength and good plasticity and toughness. The optimized mechanical properties enable the cold-drawn material to exhibit higher dimensional stability and fatigue resistance in complex stress environments (such as the high temperature and high pressure environment of nuclear power equipment), significantly extending the service life of the product. By optimizing the mechanical properties, the cold-drawn material of the present invention successfully overcomes the problems of insufficient hardness or poor ductility of cold-drawn materials in the prior art. At the same time, the residual stress is reduced through stress relief treatment, thereby improving reliability and safety during service.

[0019] Another technical problem to be solved by the present invention is to provide a method for manufacturing HS-25 cobalt-based high-temperature alloy cold-drawn materials, so as to solve the problems of complex process, unstable finished product performance, difficulty in balancing cold-drawn hardness and ductility, and high residual stress in the conventional cold-drawn material manufacturing methods in the prior art.

[0020] In order to overcome the above defects of the prior art, the present invention provides a method for manufacturing the HS-25 cobalt-based high-temperature alloy cold-drawn material, comprising the following steps:

[0021] S1: Vacuum induction smelting electrode rods: Metal chromium, nickel plate, tungsten and cobalt are loaded into a vacuum induction furnace as raw materials. After melting and refining, manganese is added and further refined. Molten steel is poured and cooled to obtain electrode rods.

[0022] S2: Electroslag remelting to produce steel ingots, melting the electrode rods in an electroslag furnace under a protective atmosphere to obtain electroslag ingots;

[0023] S3: Forging and blanking: heating the electroslag ingot to 1180±10° C., keeping the temperature, and then forging it into a square billet;

[0024] S4: rolling round steel: heating the billet to 1180±10°C and keeping the temperature, then rolling it into round bars;

[0025] S5: Solution treatment: heating the round rod to 1190±10°C, keeping the temperature, and then cooling to room temperature;

[0026] S6: Cold drawing: cold drawing the round bar and straightening it;

[0027] S7: Stress relief treatment: Heat the cold drawn material to 600-800℃, keep it at this temperature for less than 5 minutes and then air cool it to room temperature.

[0028] The present invention discloses a method for manufacturing HS-25 cobalt-based high-temperature alloy cold-drawn materials, which has the following advantages over the prior art: in conventional cold-drawn material manufacturing methods, the smelting and processing processes are complex, making it difficult to accurately control the chemical composition and grain structure of the finished product, resulting in unstable product performance. The manufacturing method of the present invention significantly reduces the impurity content (such as S and P) in the material by adopting a dual smelting process of vacuum induction smelting combined with electroslag remelting, improves the uniformity of the alloy composition, and provides a high-quality raw material foundation for subsequent processing. The prepared cold-drawn materials have stable composition and uniform grains, and can maintain excellent mechanical properties and service stability under high temperature and high pressure conditions. Conventional cold drawing usually leaves high residual stress, which affects the ductility and dimensional stability of the material. Traditional stress relief methods are often inefficient and easily lead to deterioration of material properties, while the manufacturing method of the present invention does. On the basis of controlling the amount of cold drawing deformation, a stress relief treatment process is adopted in which induction heating is quickly heated to 600-800°C and kept warm for a short time, which can effectively release residual stress while avoiding grain coarsening or excessive annealing. Improper control of conventional solution treatment temperature and time may lead to uneven distribution of strengthening phases in the alloy, affecting the high-temperature performance of the material. The manufacturing method of the present invention keeps the round rod at 1190±10°C for 1 hour and then quickly water-cools it to room temperature, ensuring that strengthening elements such as tungsten and chromium are fully dissolved in the matrix to form a uniform solid solution structure. Through continuous processing and synergistic effects between each step, the comprehensive performance of the cold-drawn material is further improved.

[0029] In a possible embodiment, in step S1, during the vacuum induction smelting process, argon gas is further injected into the smelting chamber to control the environment, and the refining is continued for less than 15 minutes, after which the steel is tapped.

[0030] Compared with the existing technology, the above technical solution can be used to fill argon as a protective gas, which can significantly reduce the corrosive effect of harmful gases (such as oxygen and nitrogen) on the molten steel during the smelting process, avoid the formation of oxide inclusions and gas pores, and thus improve the purity and composition uniformity of the alloy; by shortening the smelting time to less than 15 minutes, it can enable rapid smelting and tapping in a vacuum induction furnace, which can effectively reduce the probability of element burnout (especially volatile elements such as Mn and Cr), and at the same time prevent fluctuations in the composition of the molten steel and performance degradation caused by smelting for too long.

[0031] In a possible embodiment, in step S3, the specifications of the square billet during the forging process are 140×140×L mm, and the heating rate of the heating is less than or equal to 150° C. / hour.

[0032] Compared with the existing technology, the above technical solution is adopted, and the billet specifications are optimized to 140×140×Lmm. The precise design of the billet size reduces unnecessary heat loss and deformation stress during the billet opening process, making the internal structure of the material more uniform and the grain structure optimized; and limiting the heating rate to ≤150℃ / hour avoids the risk of temperature difference stress and surface cracks caused by excessively rapid heating, while ensuring uniform temperature inside the billet and improving subsequent forging performance.

[0033] In a possible implementation, in step S4, the round bar has a specification of Φ14 mm, and the round bar is polished or turned after rolling.

[0034] Compared with the existing technology, the adoption of the above technical solution can effectively improve the processing efficiency in the rolling process through the standardized design of the round bar diameter (Φ14mm), and provide a suitable size basis for subsequent cold drawing processing, ensuring uniform deformation during the cold drawing process. The subsequent surface treatment removes the oxide scale, cracks and surface defects on the surface of the round bar, reduces the impact of surface defects on subsequent processing performance, and improves the surface finish, thereby improving the quality of the finished cold-drawn material.

[0035] In a possible embodiment, in step S5, the condition for cooling to room temperature after heat preservation is: after heat preservation for 1 hour, taking out of the furnace and water cooling to room temperature.

[0036] Compared with the existing technology, the above technical solution can fully dissolve strengthening elements such as tungsten (W) and chromium (Cr) in the matrix by controlling the holding time to be sufficiently long (1 hour) during the solution treatment, forming a uniform solid solution structure, while avoiding uneven distribution of strengthening phases due to insufficient insulation; and rapid water cooling can quickly lower the material temperature, inhibiting the secondary precipitation or grain coarsening of strengthening elements, thereby maintaining the stability of the strengthening phase of the matrix and improving the strength and toughness of the material.

[0037] In a possible implementation, in step S6, the deformation amount of the cold drawing process is 17%-21%.

[0038] Compared with the existing technology, the above technical solution can precisely control the cold drawing deformation, introduce an appropriate amount of dislocations in the crystal structure, and avoid excessive work hardening. The moderate deformation (17%-21%) provides the best balance between the hardness and ductility of the material. Within this deformation range, the grain refinement of the material is moderate, the dislocation density increases, and the hardness is significantly improved. At the same time, the embrittlement caused by excessive deformation is avoided, ensuring the maintenance of ductility and plasticity.

[0039] In a possible implementation, in step S7, the heating is performed by induction heating, and the holding time is less than or equal to 5 minutes.

[0040] Compared with the existing technology, the above-mentioned technical solution uses electromagnetic induction to quickly heat up the material inside, which can achieve uniform, precise and rapid heating, while reducing heat loss and local overheating problems in traditional heating methods. Short-term heat preservation (≤5 minutes) can effectively release processing stress during induction heating, while avoiding grain growth or material performance degradation caused by long-term high temperature, thereby maintaining the mechanical properties of cold-drawn materials. DETAILED DESCRIPTION

[0041] First, those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the embodiments of the present application and are not intended to limit the scope of protection of the embodiments of the present application. Those skilled in the art may adjust them as needed to suit specific application scenarios.

[0042] The invention provides an HS-25 cobalt-based high-temperature alloy cold-drawn material. The chemical composition of the cold-drawn material is: C: 0.04%-0.06%, Si: 0.15%-0.20%, Mn: 1.60%-1.70%, S: ≤0.003%, P: ≤0.01%, Cr: 19.90%-20.00%, Ni: 10.00%-10.10%, W: 14.80%-14.90%, Fe: 1.20%-1.30%, and the balance is Co and other inevitable impurities.

[0043] As a preferred solution, the chemical composition of the cold-drawn material is: C: 0.05%, Si: 0.19%, Mn: 1.68%, S: 0.0022%, P: 0.008%, Cr: 19.93%, 10.03%, Ni: 14.82%, Fe: 1.28%, and the balance is Co.

[0044] As a preferred solution, the hardness HRC of the cold-drawn material is 35-40, the elongation after fracture is ≥25%, and the cross-sectional shrinkage is ≥30%.

[0045] The present invention also provides a method for manufacturing the HS-25 cobalt-based high-temperature alloy cold-drawn material, comprising the following steps:

[0046] S1: Vacuum induction smelting electrode rods: Metal chromium, nickel plate, tungsten and cobalt are loaded into a vacuum induction furnace as raw materials. After melting and refining, manganese is added and further refined. Molten steel is poured and cooled to obtain electrode rods.

[0047] S2: Electroslag remelting to produce steel ingots, melting the electrode rods in an electroslag furnace under a protective atmosphere to obtain electroslag ingots;

[0048] S3: Forging and blanking: heating the electroslag ingot to 1180±10° C., keeping the temperature, and then forging it into a square billet;

[0049] S4: rolling round steel: heating the billet to 1180±10°C and keeping the temperature, then rolling it into round bars;

[0050] S5: Solution treatment: heating the round rod to 1190±10°C, keeping the temperature, and then cooling to room temperature;

[0051] S6: Cold drawing: cold drawing the round bar and straightening it;

[0052] S7: Stress relief treatment: Heat the cold drawn material to 600-800℃, keep it at this temperature for less than 5 minutes and then air cool it to room temperature.

[0053] As a preferred solution, in step S1, during the vacuum induction smelting process, argon is also added to the smelting chamber to control the environment, and the time for continuing refining is within 15 minutes (the time from adding metal Mn to tapping is within 15 minutes), and the tapping is completed after the end.

[0054] As a preferred solution, in step S3, the specifications of the square billet during the forging process are 140×140×Lmm, and the heating rate of the heating is less than or equal to 150°C / hour.

[0055] As a preferred solution, in step S4, the specification of the round bar is Φ14 mm, and the round bar is polished or turned after rolling.

[0056] As a preferred solution, in step S5, the condition for cooling to room temperature after heat preservation is: after heat preservation for 1 hour, take out of the furnace and water-cool to room temperature.

[0057] As a preferred solution, in step S6, the deformation amount of the cold drawing treatment is 17%-21%.

[0058] As a preferred solution, in step S7, the heating is performed by induction heating, and the holding time is less than or equal to 5 minutes.

[0059] The following examples are given in combination with specific data to further explain and illustrate the technical solutions within the above scope of the present invention:

[0060] Example 1:

[0061] This embodiment provides a HS-25 cobalt-based high-temperature alloy cold-drawn material and a manufacturing method thereof. The chemical composition of the HS-25 cobalt-based high-temperature alloy cold-drawn material is:

[0062] C: 0.04%, Si: 0.15%, Mn: 1.60%, S: 0.003%, P: 0.01%, Cr: 19.90%, Ni: 10.00%, W: 14.80%, Fe: 1.20%, and the balance is Co and other inevitable impurities.

[0063] The manufacturing method comprises the following steps:

[0064] S1: Vacuum induction smelting electrode rod

[0065] Chromium, nickel, tungsten, and cobalt are loaded into a vacuum induction furnace as raw materials, where they are melted and refined under vacuum. The chemical composition is analyzed online, and after adjustment, argon is filled into the melting chamber to protect the atmosphere. Manganese is then added to continue refining, with the refining time controlled within 15 minutes. After smelting, the molten steel is poured into an ingot mold, cooled for one hour, then demolded and allowed to cool naturally to room temperature to produce an electrode rod.

[0066] S2: Electroslag remelting to produce steel ingots

[0067] The electrode rod is electroslag remelted in a protective atmosphere to obtain an electroslag ingot with a diameter of Φ360 mm.

[0068] S3: Forging

[0069] The electroslag ingot was heated to 1180±10°C at a heating rate of ≤150°C / hour, kept at this temperature for 4 hours, taken out of the furnace, and forged into a square billet with a specification of 140×140×Lmm using an electro-hydraulic hammer.

[0070] S4: Rolled round steel

[0071] The forged billet is reheated to 1180±10℃, kept at this temperature for 2 hours, and then taken out of the furnace and rolled into Φ14mm round bars in a continuous rolling mill.

[0072] S5: Solution treatment

[0073] The Φ14 mm round rod was placed in an electric heating furnace and heated to 1190±10° C. at a heating rate not higher than 150° C. / hour. The rod was kept at this temperature for 1 hour and then rapidly cooled to room temperature with water.

[0074] S6: Cold drawn products

[0075] The round bar after the solution treatment is subjected to surface lathing treatment, and then is cold drawn on a cold drawing machine under the condition of a deformation amount of 17.83% to obtain a cold drawn material, which is then straightened on a straightening machine.

[0076] S7: Stress relief

[0077] The cold drawn material was rapidly heated to 700°C by induction heating, kept at this temperature for 3 minutes, then the heating was stopped and the material was naturally cooled to room temperature.

[0078] The final test results showed that the hardness of the cold-drawn material was HRC 36-37, the elongation after fracture was 30%, and the cross-sectional shrinkage was 35%, which met the technical standard requirements.

[0079] Example 2:

[0080] This embodiment provides a HS-25 cobalt-based high-temperature alloy cold-drawn material and a manufacturing method thereof. The chemical composition of the HS-25 cobalt-based high-temperature alloy cold-drawn material is:

[0081] C: 0.06%, Si: 0.20%, Mn: 1.70%, S: 0.002%, P: 0.009%, Cr: 20.00%, Ni: 10.10%, W: 14.90%, Fe: 1.30%, and the balance is Co and other inevitable impurities.

[0082] The manufacturing method comprises the following steps:

[0083] S1: Vacuum induction smelting electrode rod

[0084] Metal chromium, nickel plate, metal tungsten and metal cobalt are loaded into a vacuum induction furnace as raw materials, melted and refined under a vacuum environment, and after adding argon protection, the composition is quickly adjusted, and then metal manganese is added to continue refining. The smelting time of continued refining is controlled within 15 minutes, and the molten steel is poured into an ingot mold. After the mold cools for 1 hour, it is demolded and naturally cooled to room temperature to obtain an electrode rod.

[0085] S2: Electroslag remelting to produce steel ingots

[0086] The electrode rods are further smelted in an electroslag furnace to produce electroslag ingots with uniform chemical composition.

[0087] S3: Forging

[0088] The electroslag ingot was heated to 1180±10℃ at a heating rate of ≤150℃ / hour, kept warm for 4 hours, taken out of the furnace, and forged into a square billet with a specification of 140×140×Lmm using an electro-hydraulic hammer.

[0089] S4: Rolled round steel

[0090] The billet is reheated to 1180±10℃ and kept at this temperature for 2 hours, and then rolled into Φ14mm round bars in a continuous rolling mill.

[0091] S5: Solution treatment

[0092] The rolled Φ14mm round bars were heated to 1190±10℃, kept at this temperature for 1 hour and then cooled to room temperature with water.

[0093] S6: Cold drawn products

[0094] The round bar after the solution treatment is polished, and then cold drawn on a cold drawing machine with a deformation of 20.42% to obtain a cold drawn material, which is then straightened on a straightening machine.

[0095] S7: Stress relief

[0096] The cold drawn material was rapidly heated to 800°C by induction heating, kept at this temperature for 4 minutes, and then stopped heating and naturally cooled to room temperature.

[0097] The final test results showed that the hardness of the cold-drawn material was HRC 39-39.5, the elongation after fracture was 28%, and the cross-sectional shrinkage was 32%, which met the technical standard requirements.

[0098] Example 3:

[0099] This embodiment provides a HS-25 cobalt-based high-temperature alloy cold-drawn material and a manufacturing method thereof. The chemical composition of the HS-25 cobalt-based high-temperature alloy cold-drawn material is:

[0100] C: 0.05%, Si: 0.19%, Mn: 1.68%, S: 0.0022%, P: 0.008%, Cr: 19.93%, Ni: 10.03%, W: 14.82%, Fe: 1.28%, and the balance is Co and other inevitable impurities.

[0101] The manufacturing method comprises the following steps:

[0102] S1: Vacuum induction smelting electrode rod

[0103] Chromium, nickel, tungsten, and cobalt are loaded into a vacuum induction furnace as raw materials, where they are melted and refined under vacuum. Samples are taken for analysis, and the composition is adjusted after adding argon protection. Manganese is then added to continue refining, with the refining time controlled to within 15 minutes. The molten steel is then poured into an ingot mold, cooled for one hour, then demolded and allowed to cool naturally to room temperature to produce an electrode rod.

[0104] S2: Electroslag remelting to produce steel ingots

[0105] The electrode rods are electroslag remelted in an electroslag furnace to produce electroslag ingots with uniform chemical composition.

[0106] S3: Forging

[0107] The electroslag ingot was heated to 1180±10℃ at a heating rate of ≤150℃ / hour, kept warm for 4 hours, taken out of the furnace, and forged into a square billet with a specification of 140×140×Lmm using an electro-hydraulic hammer.

[0108] S4: Rolled round steel

[0109] The billet is reheated to 1180±10℃ and kept at this temperature for 2 hours, and then rolled into Φ14mm round bars in a continuous rolling mill.

[0110] S5: Solution treatment

[0111] Heat a Φ14mm round rod to 1190±10℃, keep it warm for 1 hour, and then cool it to room temperature with water.

[0112] S6: Cold drawn products

[0113] The round bar is subjected to lathing treatment and then cold-drawn on a cold drawing machine at a deformation of 19.11% to obtain a cold-drawn material, which is then straightened on a straightening machine.

[0114] S7: Stress relief

[0115] The cold drawn material was rapidly heated to 700°C by induction heating, kept at this temperature for 3 minutes, then the heating was stopped and the material was naturally cooled to room temperature.

[0116] The final test results show that the hardness of the cold-drawn material is HRC 40-40.5, the elongation after fracture is 31%, and the cross-sectional shrinkage is 36%, which fully meets the technical standard requirements.

[0117] As shown in Table 1, Table 1 shows the mechanical property test results of the cold-drawn materials obtained after actual processing of Examples 1-3.

[0118] Table 1 Mechanical properties test results of stress relief cold drawn materials

[0119]

[0120] The following provides cold-drawn materials prepared by conventional methods and conventional ingredients and their related properties to further demonstrate the substantial technical advancement of the present invention:

[0121] 1. Process

[0122] Selected raw materials - vacuum induction - electroslag remelting - forging and blanking - rolling and blanking - solution heat treatment - surface polishing (or turning) - cold drawing - inspection - packaging.

[0123] 2. Vacuum induction smelting process

[0124] Vacuum induction steelmaking uses pure metal raw materials, maintaining a high vacuum throughout the entire process, which helps reduce the content of harmful elements. The Mn element, which is required by technical standards, is burned off during the electroslag process. Therefore, the Mn content in vacuum induction steelmaking is controlled to the upper limit to ensure that the Mn content after electroslag remelting meets the technical standards. The key strengthening elements Cr and W are controlled to the middle limit. The chemical composition control results of vacuum induction steelmaking are shown in Table 2 below.

[0125] Table 2 Common HS-25 vacuum induction smelting chemical composition control results (wt%)

[0126] element C Si Mn S P Cr Ni W Fe Co standard 0.05-0.15 ≤1.0 1.0-2.0 ≤0.03 ≤0.03 19.0-21.0 9.0-11.0 14.0-16.0 ≤3.0 Remain Actual measurement 0.066 0.12 1.91 0.002 0.004 20.08 10.01 15.02 0.32 Remain

[0127] 2. Electroslag remelting process

[0128] Electroslag remelting (ESR) was performed in a protective atmosphere electroslag furnace. The nominal size of the ESR ingot was 360 mm. After ESR, samples were taken from the head and tail of the ESR ingot for chemical composition analysis. The results met the requirements of technical standards. The chemical composition analysis results of the ESR ingot are shown in Table 3.

[0129] Table 3 HS-25 electroslag remelting chemical composition control results (wt%)

[0130] element C Si Mn S P Cr Ni W Fe Co standard 0.05-0.15 ≤1.0 1.0-2.0 ≤0.03 ≤0.03 19.0-21.0 9.0-11.0 14.0-16.0 ≤3.0 Remain head 0.066 0.13 1.79 0.002 0.004 20.10 10.02 15.06 0.32 Remain tail 0.062 0.12 1.68 0.002 0.004 20.01 9.97 41.97 0.41 Remain

[0131] 3. Forging process

[0132] Forging is then carried out using a 6-ton electro-hydraulic hammer. The ingot is heated to less than 600°C in a natural gas furnace for 5 hours, followed by a 4-hour hold at 1180±10°C. After the hold, it is removed from the furnace for forging. Using a direct drawing process, multiple heats are forged into a 140 x 140 x Lmm square billet. After forging, the billet is air-cooled to room temperature.

[0133] 4. Rolling and blanking process

[0134] Rolling is performed in a continuous rolling mill. Steel is placed in a walking-beam natural gas furnace at a temperature below 600°C for three hours and then held at 1180±10°C for two hours. After the holding period, the steel is removed from the furnace and rolled. The rolled steel is Φ14 x 4000mm.

[0135] 5. Solution treatment process

[0136] Load the Φ14*4000mm rolled material into an electric heating furnace with a loading temperature less than 600℃. Heat it to 1190±10℃ at a rate of no more than 150℃ / hour and keep it at that temperature for 1 hour. Then cool it to room temperature with water after it is taken out of the furnace.

[0137] 6. Cold drawing process

[0138] The φ14mm bars that have undergone solution treatment are straightened using a straightener, and one bar is randomly selected and polished to φ13.75mm using a centerless lathe; three bars are randomly selected and their surfaces are polished using a grinding wheel machine, and the size of the bars after polishing is φ13.9mm.

[0139] Comparative Example 1: A polished φ13.75 mm bar was drawn to φ12.8 mm in one step, with a deformation of 13.34%. After straightening, samples were taken to test the performance. The results are shown in Table 4.

[0140] Comparative Example 2: A polished φ13.9 mm bar was drawn to φ12.8 mm in one step, with a deformation of 15.20%. After straightening, samples were taken to test the performance. The results are shown in Table 4.

[0141] Comparative Example 3: A polished φ13.9 mm bar was drawn to φ12.6 mm in one step, with a deformation of 17.83%. After straightening, samples were taken to test the performance. The results are shown in Table 4.

[0142] Comparative Example 4: A polished φ13.9 mm bar was drawn to φ12.4 mm in one step, with a deformation of 20.42%. After straightening, samples were taken to test the performance. The results are shown in Table 4.

[0143] Table 4 Mechanical properties test results of different cold drawing deformation

[0144]

[0145] As shown in Table 4, in the comparative examples, when the cold drawing deformation is less than 17.83% (such as in Examples 1 and 2), the hardness of the cold-drawn material is insufficient (such as 30-35), making it difficult to meet the technical standard (HRC 35-40). When the deformation is higher than 20% (Example 4), although the hardness meets the requirements, the elongation after fracture and the cross-sectional shrinkage rate are greatly reduced (24% and 22% respectively), which cannot meet the technical indicators (≥25% and ≥30%). However, the present invention precisely controls the cold drawing deformation between 17% and 21%, combines the steps of the manufacturing method of the present invention with the control of its own components, and thus avoids the insufficient hardness caused by too low deformation, and effectively suppresses the decrease in ductility and plasticity caused by excessive deformation, so that the comprehensive mechanical properties of the material reach the optimal balance point.

[0146] In summary, the present invention significantly improves the comprehensive performance of hardness, ductility and plasticity by strictly controlling the cold drawing deformation in the range of 17%-21%, overcomes the technical defect that hardness and ductility are difficult to take into account in the comparative example, adopts induction heating to quickly release residual stress, retains the grain refinement effect, avoids the performance instability problem in the background technology, optimizes the chemical composition range of cold-drawn materials, significantly improves the batch-to-batch consistency of materials, especially in the field of nuclear power, and shows higher reliability, and further reduces processing stress and surface defects by limiting the forging heating rate and surface treatment after rolling, thereby ensuring the high performance of cold-drawn materials and solving the technical problems existing in the background technology.

[0147] In the description of the present application, the description with reference to the terms "one embodiment", "some embodiments", "in the present embodiment", "specific example", 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 this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, mechanisms, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0148] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A HS-25 cobalt-based high-temperature alloy cold-drawn material, characterized in that: The chemical composition of the cold drawn material is: C: 0.04%-0.06%, Si: 0.15%-0.20%, Mn: 1.60%-1.70%, S: ≤0.003%, P: ≤0.01%, Cr: 19.90%-20.00%, Ni: 10.00%-10.10%, W: 14.80%-14.90%, Fe: 1.20%-1.30%, and the balance is Co and other inevitable impurities.

2. The HS-25 cobalt-based high-temperature alloy cold-drawn material according to claim 1, characterized in that: The chemical composition of the cold drawn material is: C: 0.05%, Si: 0.19%, Mn: 1.68%, S: 0.0022%, P: 0.008%, Cr: 19.93%, Ni: 10.03%, W: 14.82%, Fe: 1.28%, and the remainder is Co and other inevitable impurities.

3. The HS-25 cobalt-based high-temperature alloy cold-drawn material according to claim 1, characterized in that: The hardness HRC of the cold drawn material is 35-40, the elongation after fracture is ≥25%, and the cross-sectional shrinkage is ≥30%.

4. A method for manufacturing the HS-25 cobalt-based high-temperature alloy cold-drawn material according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1: Vacuum induction smelting electrode rod: metal chromium, nickel plate, metal tungsten and metal cobalt are loaded into a vacuum induction furnace as raw materials, melted and refined, and then metal manganese is added and further refined, and molten steel is poured and cooled to obtain electrode rods; S2: electroslag remelting to produce steel ingots, melting the electrode rods in an electroslag furnace under a protective atmosphere to obtain electroslag ingots; S3: Forging and blanking: heating the electroslag ingot to 1180±10° C., keeping the temperature, and forging it into a square billet; S4: rolling round steel: heating the square billet to 1180±10° C. and keeping the temperature, then rolling it into a round bar; S5: Solution treatment: heating the round bar to 1190±10°C, keeping the temperature, and then cooling to room temperature; S6: cold drawing: cold drawing and straightening the round bar; S7: Stress relief treatment: Heat the cold drawn material to 600-800℃, keep it at this temperature for less than 5 minutes and then air cool it to room temperature.

5. The method for manufacturing the HS-25 cobalt-based high-temperature alloy cold-drawn material according to claim 4, characterized in that: In the step S1, during the vacuum induction smelting process, argon gas is also filled into the smelting chamber to control the environment, and the refining time is within 15 minutes, and steel is tapped after the refining is completed.

6. The method for manufacturing the HS-25 cobalt-based high-temperature alloy cold-drawn material according to claim 4, characterized in that: In the step S3, the specification of the square billet during the forging process is 140×140×Lmm, and the heating rate of the heating is less than or equal to 150°C / hour.

7. The method for manufacturing the HS-25 cobalt-based high-temperature alloy cold-drawn material according to claim 4, characterized in that: In the step S4, the specification of the round bar is Φ14 mm, and the round bar is polished or turned after rolling.

8. The method for manufacturing the HS-25 cobalt-based high-temperature alloy cold-drawn material according to claim 4, characterized in that: In the step S5, the condition of cooling to room temperature after heat preservation is: after heat preservation for 1 hour, take out of the furnace and cool to room temperature with water.

9. The method for manufacturing the HS-25 cobalt-based high-temperature alloy cold-drawn material according to claim 4, characterized in that: In the step S6, the deformation amount of the cold drawing treatment is 17%-21%.

10. The method for manufacturing the HS-25 cobalt-based high-temperature alloy cold-drawn material according to claim 4, characterized in that: In the step S7, the heating is performed by induction heating, and the heat preservation time is less than or equal to 5 minutes.

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