06Cr19Ni9 cold drawn wire and manufacturing method and application thereof

Abstract

The invention discloses a manufacturing method and application of 06Cr19Ni9 cold drawn wires. The manufacturing method is suitable for a nuclear power plant reactor control rod driving mechanism. The manufacturing method comprises the following steps: S1, carrying out multi-stage refining to control the contents of five harmful elements, namely C, Cr and Ni in molten steel; s2, the purity and the structure compactness of the steel ingot are improved through electroslag remelting; s3, the electroslag ingot is subjected to multi-heating-number forging; s4, rolling a round billet and carrying out solution treatment; s5, a 13%-20% small-step cold drawing and medium-temperature annealing circulation process is adopted for size control and structure optimization; and S6, finish turning or polishing treatment is conducted on the cold drawn wire. The performance of the prepared cold drawing wire meets the requirement of a high-strength and high-toughness material for nuclear power, and the cold drawing wire has the characteristics of uniform structure, sufficient stress release, high crack resistance and the like. The invention further discloses application of the cold drawn wire in a nuclear power reactor control rod driving mechanism, and the cold drawn wire has high reliability and high safety and is suitable for long-term service in a severe environment.

Description

Technical Field

[0001] The present invention relates to the technical field of alloy preparation, and in particular to a 06Cr19Ni9 cold drawn wire and a manufacturing method and application thereof. Background Art

[0002] In nuclear power plant reactor control rod drive mechanisms, cold-drawn wire materials are used to manufacture key components such as cylindrical pins and removal rods in rod assemblies. According to relevant technical regulations, this material must meet stringent hardness (HBW 217-285) and tensile properties (Rp0.2 410-620 MPa, Rm 650-750 MPa, and elongation after fracture A ≥ 22.5%) to ensure long-term service performance in high-temperature, high-pressure, and radiation environments.

[0003] In existing technology, the production of 06Cr19Ni9 cold-drawn wire generally involves smelting, forging, rolling, cold drawing, and annealing. However, in actual production, it is found that the final mechanical properties of the material are easily affected by the coupling of multiple factors. In particular, the rationality of the configuration of cold-drawing process parameters plays a decisive role in the stability of performance. Specifically,

[0004] Insufficient material deformation control: During the cold drawing process, deviations in the matching of parameters such as the die angle, the friction coefficient between the material and the die, the area shrinkage rate, and the hardening coefficient can easily lead to local stress concentration, causing microcracks on the surface of the steel wire or even wire breakage. For example, when the deformation exceeds the reasonable range, the material's work hardening effect is significant, resulting in excessive hardness (>285HBW), which cannot meet the requirements of subsequent machining;

[0005] Composition uniformity defects: Traditional smelting processes have insufficient control accuracy over the "five harmful" elements (Co, Cu, Nb, Ta, etc.) and key alloying elements (such as Cr, Ni, and N), which may cause fluctuations in the composition of the electroslag ingot (such as Cr content deviating from the range of 18.00-20.00%), thereby affecting the corrosion resistance and high-temperature strength of the cold-drawn wire; Low annealing process efficiency: The existing technology's repeated annealing-cold drawing cycle process has problems such as high energy consumption and long cycle time. In addition, the control accuracy of annealing temperature and holding time is insufficient (for example, the annealing temperature deviation exceeds ±20°C), which can easily lead to grain coarsening or incomplete recrystallization, resulting in a discrete distribution of the material's yield strength (Rp0.2) (below 410 MPa or above 620 MPa), making it difficult to stably meet technical requirements.

[0006] Furthermore, existing processes have limitations in controlling the surface quality of finished cold-drawn parts. When conventional lathing is insufficient (less than 0.5 mm), the fine-grained surface layer cannot be completely removed, potentially becoming the initiation point for stress corrosion cracking, impacting component reliability in the harsh environment of a nuclear reactor.

[0007] In summary, the existing technology urgently needs a manufacturing method that can accurately control the material composition, optimize the cold drawing process parameters and improve the annealing efficiency, so as to achieve stable compliance with the mechanical properties of 06Cr19Ni9 cold drawn wire and effective control of the surface quality. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a manufacturing method for 06Cr19Ni9 cold-drawn wire, so as to solve the problems in the prior art such as the easy occurrence of wire cracks or breakage, large fluctuations in material properties and uneven structure during the cold-drawing process, and ensure that the material meets the strict requirements of the control rod drive mechanism in nuclear power equipment for mechanical properties and structural consistency.

[0009] In order to overcome the above defects of the prior art, the present invention provides a method for manufacturing 06Cr19Ni9 cold drawn wire, comprising the following steps: S1: Electrode rod smelting: Use medium frequency induction furnace to smelt raw steel, followed by AOD refining, LF refining and VD vacuum degassing, and control the composition of molten steel to be: C 0.02-0.05%, Cr 18.50-19.00%, Ni 9.1-9.40%, Si 0.40-0.60%, Mn 1.40-1.65%, Co≤0.08%, P≤0.027%, S≤0.002%, N 0.04-0.08%, and the sum of the contents of the five harmful elements is ≤0.035%, and the five harmful elements are Pb, Sn, As, Sb, and Bi; S2: Electroslag remelting: After the molten steel obtained in step S1 is cast to obtain an electrode rod, the electrode rod is electroslag remelted in a crystallizer, and then de-ingoted and cooled; S3: Forging and blanking: After heating the electroslag ingot, it is forged into a blank for rolling through multiple forgings, and its blank size is controlled; S4: rolling round billet and solution treatment: heating the billet to be rolled to 1120-1160° C. and keeping the temperature for 50-70 minutes, and then solution treatment and lathing after rolling. The hardness of the round billet obtained after the solution treatment is ≤145 HBW; S5: Cold drawing and annealing cycle S51: cold drawing the round billet after the solid solution treatment, with a single cold drawing deformation of 13%-20%, and the deformation is calculated by the following formula: deformation = (cross-sectional area before cold drawing − cross-sectional area after cold drawing) / cross-sectional area before cold drawing × 100%; S52: The cold-drawn wire is then sent to a bright annealing furnace for annealing; S53: Repeat steps S51 and S52 until the wire reaches the target size; S6: Finished product processing The final cold-drawn wire is turned or polished to obtain 06Cr19Ni9 cold-drawn wire.

[0010] Compared with the prior art, the manufacturing method of the 06Cr19Ni9 cold-drawn wire of the present invention has the following advantages: the present invention systematically optimizes the key links in the manufacturing process of the 06Cr19Ni9 alloy cold-drawn wire to form a manufacturing method with high process synergy and performance stability, especially in the application scenarios of key nuclear power components such as control rod drive mechanisms. It has significant advantages: by accurately controlling the composition of the original molten steel and the total amount of the five harmful elements in the S1 step, the purity of the steel is effectively improved and the foundation for excellent organization is laid; in the S2 to S4 steps, the stable thermal field and fine composition control of the electroslag remelting, the reasonable deformation ratio in the forging and rolling process, and the medium-temperature solution treatment and lathing are combined to remove surface defects. The synergistic effect of the above factors ensures both size control and grain structure uniformity of the round billet, especially achieving blank hardness control of ≤145HBW, providing controllable deformation capability for subsequent cold working. The cold drawing and annealing cycle in step S5 establishes a dynamic balance mechanism between structural readjustment and stress release. The process combination of small-step deformation and multiple medium-temperature annealing effectively eliminates work hardening and microtexture defects caused by plastic deformation, significantly improving the consistency of mechanical properties and microstructural uniformity of the wire. Finally, the fine turning or polishing process in step S6 further optimizes the surface integrity and removes possible fine-grained layers and residual stress bands, thereby improving the fatigue life and fracture reliability of the material during actual service. Overall, the present invention does not rely on the optimization of a single parameter, but rather systematically designs and regulates the response relationship, transmission mechanism, and group characteristics between multiple key process links, thereby forming a 06Cr19Ni9 cold drawing wire preparation process with replicability, high pass rate, and long-term stability, which is significantly superior to existing similar technical solutions.

[0011] In a possible embodiment, in step S1, the conditions for smelting the raw steel in the medium frequency induction furnace are: after the smelting in the medium frequency induction furnace is completed, the composition of the molten steel is C ≥ 1.5%, Si ≤ 0.5%, and the tapping temperature is ≥ 1650°C.

[0012] Compared with the existing technology, the adoption of the above-mentioned technical scheme can quickly establish the basic chemical composition framework of the molten steel in the early stage of smelting, especially by increasing the carbon content and controlling the silicon content, which can significantly improve the decarburization kinetics and silicon-controlled stability of the subsequent AOD refining; at the same time, the higher steel-discharging temperature can effectively improve the fluidity and cleanliness of the molten steel, promote the floating and separation of inclusions, and reduce the large-particle oxidation inclusions formed in the early stage of smelting; the above-mentioned technical scheme improves the reaction efficiency of the subsequent metallurgical process by increasing the carbon potential and thermal potential, and reduces the chemical fluctuations in the intermediate links, thereby effectively improving the control accuracy of the metallurgical process and the consistency of the alloy composition, laying a stable composition foundation and cleanliness foundation for the subsequent smelting and forming processes, thereby improving the performance controllability and batch stability of the finished cold drawn wire.

[0013] In a possible embodiment, in step S1, the AOD refining conditions are as follows: after AOD refining, the composition of the molten steel is controlled to be C: 0.01-0.03%, Cr: 18.30-18.60%, Ni: 9.00-9.30%, Si: 0.30-0.50%, Mn: 1.40-1.70%, P: ≤0.026%, and S: ≤0.002%.

[0014] Compared with the existing technology, the above technical solution can achieve a stable distribution of carbon content in an extremely low range through precise oxygen blowing and decarburization control, while ensuring that key alloying elements such as Cr and Ni are not over-oxidized or lost within the control range, and the range of Si and Mn forms a stable redox balance through thermodynamic regulation. The coordinated low-phosphorus and low-sulfur control further reduces the risk of inclusion sources. Step S1 of the present invention is to achieve simultaneous decarburization, alloying and purification through multi-stage blowing, bottom blowing atmosphere control and slag composition optimization, thereby improving the composition accuracy and purity of the molten steel, significantly reducing the composition fluctuations and inclusion defects in the subsequent electroslag remelting and hot working processes, improving the organizational density and mechanical property consistency of the cold drawn wire, and meeting the quality requirements of high-reliability nuclear power materials.

[0015] In one possible embodiment, in step S1, the LF refining conditions are: using aluminum particles and calcium silicate powder for deoxidation, white slag time ≥ 30 min, and adjusting the composition in real time during the LF refining process, and controlling the ladle temperature to 1570-1580°C.

[0016] Compared with the existing technology, the above technical scheme can significantly improve the deoxidation efficiency of molten steel and the floating rate of inclusions in the deoxidation stage. Aluminum particles, as strong deoxidizers, react rapidly with residual oxygen in steel to form alumina inclusions that are easy to float out. Calcium silicon powder further promotes the denaturation of oxides and improves their fluidity and plasticity, which helps to aggregate and discharge inclusions. At the same time, by extending the white slag time, it is ensured that the slag and molten steel fully react, continuously adsorb residual oxides and inhibit the occurrence of secondary oxidation. Controlling the hanging ladle temperature at 1570-1580℃ is conducive to maintaining good fluidity and cleanliness of the molten steel. Furthermore, through the strong deoxidation + reaction slag covering system, efficient removal of non-metallic inclusions in the molten steel and stable composition control are achieved, which significantly improves the composition uniformity and cleanliness of the molten steel, and provides a good metallurgical foundation for the structural density, crack resistance and mechanical consistency during electroslag remelting and subsequent cold drawing.

[0017] In one possible embodiment, in step S2, argon protection is used during the pouring of the molten steel; and the slag material used in the electroslag remelting is a ternary slag system of CaF2, Al2O3, and CaO, and the mass ratio of CaF2, Al2O3, and CaO is 63:27:10. The conditions for the electroslag remelting are: current 11000~9000A, voltage 62~56V, and after the electroslag remelting is completed, the electroslag ingot is cooled in the crystallizer for 40~50min and then air-cooled after de-ingoting.

[0018] Compared with the existing technology, the above technical solution can greatly suppress the formation of gas inclusions and oxide inclusions during the pouring and remelting of molten steel. The argon protection effectively isolates the oxygen and nitrogen in the air from reacting with the molten steel, preventing the secondary absorption of nitrogen and oxygen. The selection of a high-fluidity slag system mainly based on CaF2 is conducive to the formation of a dense and uniform liquid slag covering layer, improving the ability to wrap and remove inclusions, and at the same time having good electroslag thermal conductivity and molten pool stability. By controlling the electroslag remelting current, voltage and cooling time, it can ensure the stability of the crystal directional solidification process and fine grains, and suppress the formation of defects such as macro segregation and central porosity.

[0019] In a possible embodiment, in step S2, the composition of the electroslag ingot satisfies the following requirements: C≤0.06%, Si≤1.00%, Mn≤2.00%, P≤0.030%, S≤0.030%, Cr: 18.00-20.00%, Ni: 9.00-12.00%, Co≤0.10%, Cu≤0.20%, and Nb+Ta≤0.15%.

[0020] Compared with existing technologies, this method significantly improves the compositional uniformity and purity of the ingot after electroslag remelting. In particular, it precisely controls the five harmful elements (Co, Cu, Nb, and Ta), helping to reduce the material's embrittlement tendency and the risk of isomerized precipitation during subsequent deformation and service. Through molten pool stability control during remelting and the purification of the electroslag slag system, trace harmful elements are fully separated. The redistribution of composition at the solidification interface limits the segregation and enrichment of alloying elements. Furthermore, the control range of Cr and Ni covers the typical alloy ratio of 06Cr19Ni9 stainless steel, which is beneficial for stabilizing the austenitic structure and improving corrosion resistance. Ultimately, this composition range ensures that the electroslag ingot has good metallurgical uniformity, structural density, and subsequent processing stability, providing a reliable compositional guarantee and structural foundation for cold drawing of nuclear power wire.

[0021] In a possible embodiment, in step S3, the conditions for heating and keeping the electroslag ingot are: heating to 1140-1180° C. and keeping warm for 50-70 minutes.

[0022] Compared with the existing technology, the above technical scheme can effectively improve the plasticity and processing performance of the electroslag ingot during the forging process, so that it is in the optimal thermoplastic range, avoiding ingot core cracks caused by too low temperature, or grain coarsening and center loosening due to too high temperature. In the present invention, 1140-1180℃ belongs to the intersection area of the upper limit of the austenite stable zone and the recrystallization active zone. In this temperature range, the grains have good plasticity and have sufficient driving force to promote deformation recrystallization, inhibit grain growth and enhance grain boundary stability.

[0023] In a possible embodiment, in step S4, the temperature of the solution treatment is 1020-1060°C; in step S5, the conditions of the annealing treatment are: keeping at 1040-1060°C for 40-60 minutes and then water cooling.

[0024] Compared with the prior art, the above-mentioned technical solution is adopted. In step S4, the internal stress of the material can be fully released and the structure can be completely recrystallized in the high temperature section. The initial heating treatment ensures grain boundary migration and composition homogenization, avoiding the problems of structural banding, retention in the two-phase region or insufficient recrystallization due to insufficient temperature. The solution treatment temperature zone is set in the austenite phase stability zone, so that the carbides and precipitates are fully dissolved into the matrix, effectively improving the structure consistency and corrosion resistance. In step S5, the annealing temperature and holding time match the degree of work hardening after cold drawing, which can moderately restore the dislocation density and improve the grain morphology. The water cooling method inhibits the formation of re-precipitated phases, ensuring mechanical properties and surface stability. The above-mentioned technical solution of the present invention realizes the continuous control of "structure optimization-stress release-surface strengthening" through a gradual heat treatment path, which can ultimately significantly improve the plasticity and toughness of the cold-drawn wire, and achieve edge-center consistency at the microstructure level, thereby enhancing the crack resistance and dimensional stability during service.

[0025] The second technical problem to be solved by the present invention is to provide a 06Cr19Ni9 cold drawn wire to solve the problems existing in the prior art of excessive wire hardness, performance fluctuations, residual surface fine grain layer and easy occurrence of service cracks.

[0026] In order to overcome the above defects of the prior art, the present invention provides a 06Cr19Ni9 cold drawn wire manufactured by the manufacturing method, and the performance of the 06Cr19Ni9 cold drawn wire meets the following requirements: Hardness HBW 217-285; Yield strength Rp0.2 is 410-620MPa; Tensile strength Rm is 650-750MPa; Elongation at break A≥22.5%.

[0027] Compared with the prior art, the 06Cr19Ni9 cold-drawn wire of the present invention has the following advantages: the 06Cr19Ni9 cold-drawn wire of the present invention optimizes the discontinuous cold working method of the prior art that relies on a single large deformation + a single annealing into a cyclic control process based on the coordination of small and medium-step deformation, multiple medium-temperature annealing, and fine turning and polishing; by controlling the processing deformation amount (13%-20%) and the time / temperature range of each annealing round (1040-1060°C, 40-60min), the triple process of "recrystallization-texture reconstruction-stress release" is realized on the microstructure evolution path, and at the same time, combined with turning and polishing to remove the surface fine grain layer, the existence of the microcrack initiation zone is effectively avoided. Related features include: medium-temperature solid solution to reduce hardness, closed-loop control of deformation, water cooling after annealing, and polishing to remove surface defects, forming a "tissue control chain" for the entire process. This cold-drawn wire not only has good strength-toughness matching and dimensional consistency, but also significantly improves long-term service stability and crack resistance in applications in nuclear power control rod drive mechanisms, solving the technical problems of poor structural consistency and insufficient reliability of existing cold-drawn products from the source.

[0028] The third technical problem to be solved by the present invention is to provide an application of 06Cr19Ni9 cold-drawn wire to solve the problems existing in the prior art of insufficient service reliability, high fracture risk and poor structural consistency when used in nuclear power plant control rod drive mechanism components.

[0029] In order to overcome the above defects of the prior art, the present invention provides an application of 06Cr19Ni9 cold drawn wire, which includes the application of the 06Cr19Ni9 cold drawn wire in a control rod drive mechanism of a nuclear power plant reactor.

[0030] Compared with the prior art, the application of a 06Cr19Ni9 cold-drawn wire of the present invention has the following advantages: the 06Cr19Ni9 cold-drawn wire of the present invention replaces the traditional method of relying on conventional austenitic stainless steel bars to turn components, and adopts 06Cr19Ni9 cold-drawn wire that has undergone multiple cold-drawing-annealing cycles and has precise microstructure control, and is directly used for high-precision components such as cylindrical pins and disassembly rods in the control rod drive mechanism of a nuclear power reactor. After the cold-drawn wire is deformed, the annealing stress is released, and the surface fine-grained layer is removed, it forms a material state with excellent mechanical properties, uniform microstructure, controllable work hardening, and stable surface state. The wire can stably serve in the high-temperature, high-radiation, and long-term load internal environment of a reactor, and the risk of crack initiation and propagation is significantly reduced. Key technical features include: controllable hardness within the range of 217-285HBW after cold drawing, yield strength of 410-620MPa and elongation ≥22.5%, and lathing depth ≥0.5mm, which ensure component forming accuracy, connection strength and dynamic response consistency. The application of the cold-drawn wire of the present invention in the control rod drive mechanism greatly improves the structural reliability, operational safety margin and maintenance cycle of the entire machine, meets the stringent requirements of nuclear power equipment for high material consistency, high stability and high safety, and comprehensively solves the problem of poor service adaptability of traditional materials in key parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the center organization diagram of 06Cr19Ni9 cold drawing wire; Figure 2 This is the edge structure diagram of 06Cr19Ni9 cold drawn wire. DETAILED DESCRIPTION

[0032] First, those skilled in the art should understand that these embodiments are merely for explaining the technical principles of the embodiments of the present invention and are not intended to limit the scope of protection of the embodiments of the present invention. Those skilled in the art may make adjustments as needed to adapt to specific application scenarios.

[0033] The present invention provides a method for manufacturing 06Cr19Ni9 cold-drawn wire, comprising the following steps: S1: Electrode rod smelting: Use medium frequency induction furnace to smelt raw steel, followed by AOD refining, LF refining and VD vacuum degassing, and control the composition of molten steel to be: C 0.02-0.05%, Cr 18.50-19.00%, Ni 9.1-9.40%, Si 0.40-0.60%, Mn 1.40-1.65%, Co≤0.08%, P≤0.027%, S≤0.002%, N 0.04-0.08%, and the sum of the contents of the five harmful elements is ≤0.035%, and the five harmful elements are Pb, Sn, As, Sb, and Bi; S2: Electroslag remelting: After the molten steel obtained in step S1 is cast to obtain an electrode rod, the electrode rod is electroslag remelted in a crystallizer, and then de-ingoted and cooled; S3: Forging and blanking: After heating the electroslag ingot, it is forged into a blank for rolling through multiple forgings, and its blank size is controlled; S4: rolling round billet and solution treatment: heating the billet to be rolled to 1120-1160° C. and keeping the temperature for 50-70 minutes, and then solution treatment and lathing after rolling. The hardness of the round billet obtained after the solution treatment is ≤145 HBW; S5: Cold drawing and annealing cycle S51: cold drawing the round billet after the solid solution treatment, with a single cold drawing deformation of 13%-20%, and the deformation is calculated by the following formula: deformation = (cross-sectional area before cold drawing − cross-sectional area after cold drawing) / cross-sectional area before cold drawing × 100%; S52: The cold-drawn wire is then sent to a bright annealing furnace for annealing; S53: Repeat steps S51 and S52 until the wire reaches the target size; S6: Finished product processing The final cold-drawn wire is turned or polished to obtain 06Cr19Ni9 cold-drawn wire.

[0034] As a preferred solution, in step S1, the conditions for smelting the raw steel in the medium frequency induction furnace are: after the smelting in the medium frequency induction furnace is completed, the composition of the molten steel is C ≥ 1.5%, Si ≤ 0.5%, and the tapping temperature is ≥ 1650°C.

[0035] As a preferred solution, in step S1, the conditions for AOD refining are: after AOD refining, the composition of the molten steel is controlled to be C: 0.01-0.03%, Cr: 18.30-18.60%, Ni: 9.00-9.30%, Si: 0.30-0.50%, Mn: 1.40-1.70%, P: ≤0.026%, and S: ≤0.002%.

[0036] As a preferred solution, in step S1, the LF refining conditions are: using aluminum particles and calcium silicate powder for deoxidation, white slag time ≥ 30 min, and adjusting the composition in real time during the LF refining process, and controlling the hanging bag temperature to 1570-1580°C.

[0037] As a preferred solution, in step S2, argon protection is used during the pouring of the molten steel; and the slag material used in the electroslag remelting is a ternary slag system of CaF2, Al2O3, and CaO, and the mass ratio of CaF2, Al2O3, and CaO is 63:27:10. The conditions for the electroslag remelting are: current 11000~9000A, voltage 62~56V, and after the electroslag remelting is completed, the electroslag ingot is cooled in the crystallizer for 40~50min and then air-cooled after being de-ingoted.

[0038] As a preferred solution, in step S2, the composition of the electroslag ingot satisfies: C≤0.06%, Si≤1.00%, Mn≤2.00%, P≤0.030%, S≤0.030%, Cr: 18.00-20.00%, Ni: 9.00-12.00%, Co≤0.10%, Cu≤0.20%, and Nb+Ta≤0.15%.

[0039] As a preferred solution, in step S3, the conditions for heating and keeping the electroslag ingot are: heating to 1140-1180° C. and keeping warm for 50-70 minutes.

[0040] As a preferred solution, in step S4, the temperature of the solution treatment is 1020-1060°C; in step S5, the conditions of the annealing treatment are: keeping at 1040-1060°C for 40-60 minutes and then water cooling.

[0041] The present invention also provides a 06Cr19Ni9 cold drawn wire manufactured by the manufacturing method, wherein the properties of the 06Cr19Ni9 cold drawn wire meet the following requirements: Hardness HBW 217-285; Yield strength Rp0.2 is 410-620MPa; Tensile strength Rm is 650-750MPa; Elongation at break A≥22.5%.

[0042] The present invention also provides an application of the 06Cr19Ni9 cold-drawn wire, which includes application of the 06Cr19Ni9 cold-drawn wire in a control rod drive mechanism of a nuclear power plant reactor.

[0043] The following provides examples combined with specific data to further expand and explain the above technical solutions of the present invention: Example 1: This embodiment provides a 06Cr19Ni9 cold-drawn wire and a manufacturing method thereof. The chemical composition of the cold-drawn wire is shown in Table 1 (unit: wt%): C 0.031 wt%, Si 0.42 wt%, Mn 1.55 wt%, P 0.025 wt%, S 0.0022 wt%, Cr 19.02wt%, Ni 9.46 wt%, N 0.059 wt%, Co 0.052 wt%, Cu 0.088 wt%, Nb+Ta 0.029 wt%, the sum of the five harmful elements (Pb, Sn, As, Sb, Bi) ≤ 0.035%.

[0044] The manufacturing method comprises the following steps: S1: Electrode rod smelting: The raw steel is smelted in a medium frequency induction furnace, followed by AOD refining, LF refining and VD vacuum degassing, specifically including: Medium frequency induction furnace smelting: before tapping, the molten steel [C%] = 2.0%, [Si%] = 0.25% (range ≤ 0.5%), and the tapping temperature is 1700℃.

[0045] AOD refining: decarburization to C=0.02%, Cr=18.45%, Ni=9.15%.

[0046] LF refining: white slag time 40min, ladle temperature 1575℃.

[0047] The composition of the molten steel after VD vacuum degassing meets the following requirements: C 0.02-0.05%, Cr 18.50-19.00%, Ni 9.1-9.40%, Si0.40-0.60%, Mn 1.40-1.65%, Co≤0.08%, P≤0.027%, S≤0.002%, N 0.04-0.08%, and the total content of the five harmful elements is ≤0.035%, and the five harmful elements are Pb, Sn, As, Sb, and Bi; S2: Electroslag remelting: After the molten steel obtained in step S1 is cast to obtain electrode rods, the electrode rods are electroslag remelted in a crystallizer, followed by stripping and cooling. The crystallizer specification is Φ525mm, the slag mass ratio is CaF2:Al2O3:CaO = 63:27:10, and the electroslag remelting conditions are: current 10000A, voltage 59V, and stripping and cooling time 45min; S3: Forging and blanking: The electroslag ingot is heated to 1160℃ and forged into a 140mm×140mm square billet through three forging steps; S4: Rolling round billet and solution treatment: The forging billet is heat treated at a temperature of 1140°C and kept at this temperature for 60 minutes, and then rolled into a Φ20mm round billet. After rolling, it is solution treated and turned at a temperature of 1040°C and kept at this temperature for 60 minutes. The hardness after turning is 139 HBW. S5: Cold drawing and annealing cycle S51: cold drawing the round billet after the solid solution treatment, with a single cold drawing deformation of 16.5%, which is calculated by the following formula: deformation = (cross-sectional area before cold drawing − cross-sectional area after cold drawing) / cross-sectional area before cold drawing × 100%; S52: The cold-drawn wire is then sent to a bright annealing furnace for annealing at a temperature of 1050° C. for 50 minutes. S53: After 4 cold drawing-annealing cycles, the final wire size is Φ13mm; S6: The final cold-drawn wire is turned or polished, with a turning amount of 0.5 mm, and there is no fine-grained layer on the surface of the final cold-drawn wire.

[0048] The microstructure of the 06Cr19Ni9 cold drawn wire of the present invention after multiple cold drawing and bright annealing treatments shows good uniformity, such as Figure 1 、 Figure 2 As shown, marginal tissue ( Figure 1 ) The grains are slightly fine and have a slight processing orientation, reflecting that the cold deformation has a strong influence, but no serious distortion or cracks occur; the central structure ( Figure 2 ) exhibits an equiaxed grain structure with uniform grain size, indicating sufficient annealing and good stress release. Overall, the material exhibits uniform radial structure, demonstrating the effective control of the manufacturing method of the present invention, which helps improve the mechanical performance stability and service reliability of the product.

[0049] Example 2 This embodiment provides a 06Cr19Ni9 cold-drawn wire and a manufacturing method thereof. The chemical composition of the cold-drawn wire is shown in Table 1 (unit: wt%): C 0.026 wt%, Si 0.48 wt%, Mn 1.63 wt%, P 0.026 wt%, S 0.0018 wt%, Cr 18.85wt%, Ni 9.37 wt%, N 0.062 wt%, Co 0.033 wt%, Cu 0.12 wt%, Nb+Ta 0.035 wt%, the sum of the five harmful elements (Pb, Sn, As, Sb, Bi) ≤ 0.035%.

[0050] The manufacturing method comprises the following steps: S1: Electrode rod smelting The raw steel is smelted in a medium frequency induction furnace, followed by AOD refining, LF refining and VD vacuum degassing, specifically including: Medium frequency induction furnace smelting: before tapping, the molten steel [C%] = 1.5%, [Si%] = 0.5%, and the tapping temperature is 1650℃; AOD refining: decarburize the molten steel to C=0.01%, Cr=18.30%, Ni=9.00%; LF refining: white slag time 30min, ladle temperature 1570℃; The mass ratio of the steel liquid after VD vacuum degassing meets the following requirements: C 0.02-0.05%, Cr 18.50-19.00%, Ni 9.1-9.40%, Si 0.40-0.60%, Mn 1.40-1.65%, Co≤0.08%, P≤0.027%, S≤0.002%, N 0.04-0.08%, and the total of the five harmful elements is ≤0.035%.

[0051] S2: Electroslag Remelting After the molten steel obtained in step S1 is cast to obtain an electrode rod, the electrode rod is electroslag remelted in a crystallizer, and then de-ingoted and cooled: Crystallizer specifications: Φ500mm.

[0052] Slag mass ratio: CaF2:Al2O3:CaO=63:27:10.

[0053] Electroslag remelting conditions: current 9000A, voltage 56V, ingot stripping cooling time 40min.

[0054] S3: Forging The electroslag ingot is heated to 1140℃ and forged into a 140mm×140mm square billet through three forgings.

[0055] S4: Rolling round billet and solution treatment The forging blank is heat treated: Billet heating temperature: 1120℃, keep warm for 50min; Rolled into Φ20mm round billet.

[0056] After rolling, it is solution treated and polished. The solution treatment temperature is 1020℃, and the temperature is kept for 40 minutes. The hardness after polishing is 141HBW.

[0057] S5: Cold drawing and annealing cycle S51: cold drawing the round billet after the solution treatment, with a single cold drawing deformation of 13%. The deformation calculation formula is the same as that in Example 1.

[0058] S52: The cold-drawn wire is then sent to a bright annealing furnace for annealing at a temperature of 1040° C. for 40 minutes.

[0059] S53: After 5 cold drawing-annealing cycles, the final wire size is Φ13mm.

[0060] S6: Finished product processing The final cold drawn wire is polished with a polishing amount of 0.5 mm and no fine grain layer on the surface.

[0061] Example 3 This embodiment provides a 06Cr19Ni9 cold-drawn wire and a manufacturing method thereof. The chemical composition of the cold-drawn wire is shown in Table 1 (unit: wt%): C 0.025 wt%, Si 0.44 wt%, Mn 1.54 wt%, P 0.026 wt%, S 0.0023 wt%, Cr 18.92wt%, Ni 9.43 wt%, N 0.055 wt%, Co 0.035 wt%, Cu 0.092 wt%, Nb+Ta 0.040 wt%, the sum of the five harmful elements (Pb, Sn, As, Sb, Bi) ≤ 0.035%.

[0062] The manufacturing method comprises the following steps: S1: Electrode rod smelting The raw steel is smelted in a medium frequency induction furnace, followed by AOD refining, LF refining and VD vacuum degassing, specifically including: Medium frequency induction furnace smelting: before tapping, the molten steel [C%] = 3.0% (range ≥ 1.5% upper limit verification value), [Si%] = 0.1% (range ≤ 0.5% safety value), and the tapping temperature is 1750°C (out-of-range verification of process stability).

[0063] AOD refining: decarburization to C=0.03% (range 0.01-0.03% upper limit), Cr=18.60% (range 18.30-18.60% upper limit), Ni=9.30% (range 9.00-9.30% upper limit).

[0064] LF refining: white slag time 45min (range ≥30min upper limit), hanging bag temperature 1580℃ (range 1570-1580℃ upper limit).

[0065] The composition of the molten steel after VD vacuum degassing meets the following requirements: C 0.02-0.05%, Cr 18.50-19.00%, Ni 9.1-9.40%, Si0.40-0.60%, Mn 1.40-1.65%, Co≤0.08%, P≤0.027%, S≤0.002%, N 0.04-0.08%, and the total content of the five harmful elements is ≤0.035%, and the five harmful elements are Pb, Sn, As, Sb, and Bi; S2: Electroslag Remelting After the molten steel obtained in step S1 is cast to obtain an electrode rod, the electrode rod is electroslag remelted in a crystallizer, and then de-ingoted and cooled: Crystallizer specifications: Φ550mm; Slag mass ratio: CaF2:Al2O3:CaO =63:27:10.

[0066] Electroslag remelting conditions: current 11000A, voltage 62V, ingot stripping cooling time 50min.

[0067] S3: Forging The electroslag ingot is heated to 1180℃ and forged into a 140mm×140mm square billet through three forging steps.

[0068] S4: Rolling round billet and solution treatment The forging blank is heat treated: Billet heating temperature: 1160℃, keep warm for 70min; Rolled to Φ20mm round billet; After rolling, it is solution treated and polished. The solution treatment temperature is 1060℃, and the temperature is kept for 60 minutes. The hardness after polishing is 144HBW.

[0069] S5: Cold drawing and annealing cycle S51: cold drawing the round billet after the solution treatment, with a single cold drawing deformation of 20%. The deformation calculation formula is the same as that in Example 1.

[0070] S52: The cold-drawn wire is then sent to a bright annealing furnace for annealing at a temperature of 1060° C. for 60 minutes.

[0071] S53: After three cold drawing-annealing cycles, the final wire size is Φ12mm.

[0072] S6: Finished product processing The final cold-drawn wire is polished by 0.4 mm until there is no fine grain layer on the surface of the cold-drawn wire.

[0073] Table 1 Chemical composition of 06Cr19Ni9 cold drawn wire (wt%) The properties of the cold drawn wires obtained in Examples 1-3 at room temperature are shown in Table 2: Table 2 Mechanical properties of 06Cr19Ni9 bars According to the test results of Examples 1-3, the 06Cr19Ni9 cold-drawn wire of the present invention successfully achieves a balance between material strength, plasticity, and hardness by precisely controlling the steel liquid composition (including C 0.02-0.05% and the sum of five harmful elements ≤0.035%) during the electrode rod smelting stage, optimizing the ingot density by electroslag remelting (slag-to-material ratio 63:27:10 and gradient current control), reducing the billet hardness by solution treatment (hardness ≤145 HBW after holding at 1040±20°C), and coordinated control of the deformation amount (13-20%) and annealing temperature (1050±10°C) during the cold drawing-annealing cycle. As shown in Table 2, the yield strength of Example 1 reached 594 MPa and the elongation after fracture was 36.0%. The mechanical properties of Examples 2 and 3 (Rp0.2 571-572 MPa, Rm 709-715 MPa, HBW 224-228) both stably met the technical material requirements for the control rod drive mechanism of nuclear power plants (Rp0.2 410-620 MPa, Rm 650-750 MPa, HBW 217-285). This demonstrates that the multi-process synergistic mechanism of component purity control, deformation-induced microstructure refinement, and annealing to eliminate internal stress can effectively resolve the contradiction between the high strength and toughness requirements of cold drawing and the risk of processing defects in the harsh nuclear energy environment. This provides a replicable process path for the high-reliability manufacturing of nuclear-grade stainless steel wire.

[0074] In the description of the present invention, the reference terms "one embodiment", "some embodiments", "in the present embodiment", "specific examples", or "some examples" mean 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 invention. 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 any one or more embodiments or examples in a suitable manner. 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 without contradiction.

[0075] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention 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 invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for manufacturing 06Cr19Ni9 cold drawn wire, characterized in that: The following steps are involved: S1: Electrode rod smelting: Use medium frequency induction furnace to smelt raw steel, followed by AOD refining, LF refining and VD vacuum degassing, and control the composition of molten steel to be: C 0.02-0.05%, Cr 18.50-19.00%, Ni 9.1-9.40%, Si 0.40-0.60%, Mn 1.40-1.65%, Co≤0.08%, P≤0.027%, S≤0.002%, N 0.04-0.08%, and the sum of the contents of the five harmful elements is ≤0.035%, and the five harmful elements are Pb, Sn, As, Sb, and Bi; S2: Electroslag remelting: After the molten steel obtained in step S1 is cast to obtain an electrode rod, the electrode rod is electroslag remelted in a crystallizer, and then de-ingoted and cooled; S3: Forging and blanking: The electroslag ingot is heated and forged into a blank for rolling through multiple forgings; S4: rolling round billet and solution treatment: heating the billet to be rolled to 1120-1160° C. and keeping the temperature for 50-70 minutes, and then solution treatment and lathing after rolling. The hardness of the round billet obtained after the solution treatment is ≤145 HBW; S5: Cold drawing and annealing cycle S51: cold drawing the round billet after the solid solution treatment, with a single cold drawing deformation of 13%-20%, and the deformation is calculated by the following formula: deformation = (cross-sectional area before cold drawing − cross-sectional area after cold drawing) / cross-sectional area before cold drawing × 100%; S52: The cold-drawn wire is then sent to a bright annealing furnace for annealing; S53: Repeat steps S51 and S52 until the wire reaches the target size; S6: Finished product processing The final cold-drawn wire is turned or polished to obtain 06Cr19Ni9 cold-drawn wire.

2. The manufacturing method according to claim 1, characterized in that In step S1, the conditions for smelting the raw steel in the medium frequency induction furnace are: after the smelting in the medium frequency induction furnace is completed, the composition of the molten steel is C ≥ 1.5%, Si ≤ 0.5%, and the tapping temperature is ≥ 1650°C.

3. The manufacturing method according to claim 1, characterized in that In step S1, the AOD refining conditions are as follows: after AOD refining, the composition of the molten steel is controlled to be C: 0.01-0.03%, Cr: 18.30-18.60%, Ni: 9.00-9.30%, Si: 0.30-0.50%, Mn: 1.40-1.70%, P: ≤0.026%, and S: ≤0.002%.

4. The manufacturing method according to claim 1, characterized in that In step S1, the LF refining conditions are: using aluminum particles and calcium silicate powder for deoxidation, white slag time ≥ 30 min, and adjusting the composition in real time during the LF refining process, and controlling the hanging bag temperature to 1570-1580°C.

5. The manufacturing method according to claim 1, characterized in that In step S2, argon gas is used for protection during the pouring of the molten steel; and the slag material used in the electroslag remelting is a ternary slag system of CaF2, Al2O3, and CaO, and the mass ratio of CaF2, Al2O3, and CaO is 63:27:

10. The conditions of the electroslag remelting are: current 11000-9000A, voltage 62-56V, and after the electroslag remelting is completed, the electroslag ingot is cooled in the crystallizer for 40-50 minutes and then air-cooled after being de-ingoted.

6. The manufacturing method according to claim 5, characterized in that In the step S2, the composition of the electroslag ingot satisfies the following requirements: C≤0.06%, Si≤1.00%, Mn≤2.00%, P≤0.030%, S≤0.030%, Cr: 18.00-20.00%, Ni: 9.00-12.00%, Co≤0.10%, Cu≤0.20%, and Nb+Ta≤0.15%.

7. The manufacturing method according to claim 1, characterized in that In step S3, the electroslag ingot is heated to a temperature of 1140-1180°C.

8. The manufacturing method according to claim 1, characterized in that In the step S4, the temperature of the solution treatment is 1020-1060° C.; in the step S5, the conditions of the annealing treatment are: keeping at 1040-1060° C. for 40-60 minutes and then cooling with water.

9. A 06Cr19Ni9 cold drawn wire produced by the production method according to any one of claims 1 to 8, characterized in that: The properties of the 06Cr19Ni9 cold drawn wire meet the following requirements: Hardness HBW 217-285; Yield strength Rp0.2 is 410-620MPa; Tensile strength Rm is 650-750MPa; Elongation at break A≥22.5%.

10. An application of the 06Cr19Ni9 cold drawn wire according to claim 9, characterized in that: The application includes the application of the 06Cr19Ni9 cold drawn wire in a control rod drive mechanism of a nuclear power plant reactor.

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