Preparation method of variable-form CoCrMo alloy wire

Abstract

The invention discloses a preparation method of a variable-form CoCrMo alloy wire, which comprises the following steps: preparing a CoCrMo alloy bar with certain grain size, mechanical property and geometric dimension, and taking the CoCrMo alloy bar as a base material for preparing the CoCrMo alloy wire; the CoCrMo alloy bar is subjected to annealing, rounding and peeling; subsequent plastic processing is carried out on the CoCrMo alloy bar, two times of large deformation cold drawing, one time of medium deformation cold drawing and a plurality of times of small deformation cold drawing are carried out in sequence, medium-high temperature heat treatment and argon cooling are carried out after each time of cold drawing, low temperature heat treatment is carried out after the last time of cold drawing, and finally the deformed CoCrMo alloy wire is obtained. In each link of the whole cold drawing process, the wire does not crack, and the finally prepared CoCrMo alloy wire is fine in grain and uniform and stable in structure.

Description

Technical Field

[0001] This invention belongs to the field of CoCrMo alloy material preparation technology, specifically relating to a method for preparing modified CoCrMo alloy wire. The CoCrMo alloy wire prepared by this method is particularly suitable for the biomedical field. Background Technology

[0002] CoCrMo alloys, with their high strength, high hardness, excellent wear resistance, and corrosion resistance, demonstrate irreplaceable value in the aerospace and biomedical fields. In aerospace, CoCrMo alloys can be used to manufacture high-temperature, high-strength components such as turbine blades and engine parts that withstand extreme environments. In biomedicine, with the increasing aging of the global population, the demand for joint replacement surgery has surged. Previously, titanium alloys or stainless steel were often used as replacement materials in joint replacement surgeries, but these materials have poor wear resistance. CoCrMo alloys, due to their better biocompatibility and superior wear resistance, have become one of the preferred materials for artificial joint replacement.

[0003] Early methods of using cast CoCrMo alloys to manufacture hip joints resulted in wear and corrosion issues after long-term service, failing to meet long-term service requirements. While forged CoCrMo alloys offered a more ideal service life, they suffered from poor plastic deformation capacity, susceptibility to cracking during deformation, and the formation of banded grains and localized coarse grains. To date, no reported technology exists for preparing forged CoCrMo alloy bars that can prevent cracking during production and ensure stable microstructure in the final bar.

[0004] Against this backdrop, the preparation technology of CoCrMo filaments has received increasing attention. As an important material form, CoCrMo filaments exhibit unique application value in fields such as micro-part manufacturing and precision medical devices, and are particularly suitable for applications such as the fabrication of auxiliary components for high-precision orthopedic implants. However, due to the inherent characteristics of CoCrMo alloys, the preparation of their filaments faces challenges similar to those encountered in forging processes. Solving the problem of filaments being easily broken or unable to be stretched during preparation, and ensuring stable filament microstructure and excellent mechanical properties, is a key prerequisite for expanding the applications of CoCrMo alloy filaments in more fields.

[0005] In the field of CoCrMo alloy wire preparation technology, existing research mostly revolves around traditional plastic processing techniques. Early attempts used cold drawing to prepare wires, but due to the poor plastic deformation capacity of CoCrMo alloys, cracking easily occurs during drawing, especially when the deformation is large. Cracks propagate from the surface to the interior, resulting in a high scrap rate for the wires. To improve this situation, researchers introduced an intermediate annealing process, annealing between multiple drawing operations to restore the material's plasticity. However, controlling the annealing parameters is difficult. If the annealing temperature is too high or the annealing time is too long, coarse grains will form inside the wire, affecting its mechanical properties. If the annealing temperature is too low or the annealing time is insufficient, work hardening cannot be fully eliminated, leading to cracking during subsequent drawing processes, affecting subsequent processing performance, and causing significant fluctuations in wire properties.

[0006] Furthermore, the raw materials used to prepare CoCrMo alloy wires require pre-treatment through rolling and / or forging. However, banded grains and localized coarse grains are easily generated during the rolling and / or forging pre-treatment stages, leading to uneven microstructure in the wires. This results in unstable performance during processing and service, making it difficult to meet the consistent material performance requirements of high-precision applications. Frequent cracking and poor performance stability necessitate frequent process adjustments and quality inspections, increasing production steps and time costs, which is detrimental to large-scale production. Therefore, there is an urgent need to develop a method for preparing modified CoCrMo alloy wires to address the problems existing in the current technology. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides a method for preparing modified CoCrMo alloy wire, the preparation method comprising the following steps in sequence:

[0008] Step 1: Prepare CoCrMo alloy bars with certain grain size, mechanical properties and geometric dimensions according to the designed forging-radial forging-hot rolling method, and use the CoCrMo alloy bars as the base material for preparing CoCrMo alloy wires;

[0009] Step 2: Place the CoCrMo alloy bar into a heat treatment furnace for annealing.

[0010] Step 3: Transfer the annealed CoCrMo alloy bar to the drawing machine, pre-cool and draw it according to the designed rounding dimensions to correct the shape and size of the CoCrMo alloy bar so that its cross-section is circular. Then, peel the rounded CoCrMo alloy bar according to the designed peeling thickness.

[0011] Step 4: After the peeling process is completed, the CoCrMo alloy bar is transferred to the drawing machine for the first cold drawing to obtain wire. The wire obtained by the first cold drawing is placed in a vacuum heat treatment furnace for the first vacuum annealing treatment. Then, argon gas is introduced into the vacuum heat treatment furnace to perform the first gas cooling of the wire.

[0012] Step 5: After the first air cooling is completed, the wire is transferred to the drawing machine for a second cold drawing and further processed into wire. The wire obtained from the second cold drawing is placed in a vacuum heat treatment furnace for a second vacuum annealing treatment. Then, argon gas is introduced into the vacuum heat treatment furnace to perform a second air cooling on the wire.

[0013] Step 6: After the second air cooling is completed, the wire is transferred to the drawing machine for a third cold drawing and further processed into wire. The wire obtained by the third cold drawing is placed in a vacuum heat treatment furnace for a third vacuum annealing treatment. Then, argon gas is introduced into the vacuum heat treatment furnace to perform a third air cooling on the wire.

[0014] Step 7: After the third air cooling is completed, the wire is transferred to the drawing machine for several subsequent cold drawing and further wire production until the wire diameter reaches the required size. After each cold drawing, the wire is placed in a vacuum heat treatment furnace for vacuum annealing. Then, argon gas is introduced into the vacuum heat treatment furnace to air cool the wire, and finally, the modified CoCrMo alloy wire is obtained.

[0015] Step 8: Transfer the finally obtained deformed CoCrMo alloy wire to a straightening machine for straightening, and then cut, package, and store it according to the required dimensions.

[0016] Preferably, in step one, the preparation method of the CoCrMo alloy rod includes the following steps:

[0017] Step 1.1: Prepare CoCrMo alloy ingots using a duplex melting method and then homogenize them;

[0018] Step 1.2: Transfer the CoCrMo alloy ingot to a press for the first forging to obtain a billet. Then, place the billet in a heat treatment furnace for the first annealing treatment. The first forging process involves several forging passes until the total deformation reaches 8-20%, with the deformation between adjacent forging passes being 1-2%. The annealing temperature for the first annealing treatment is 1150-1220℃, and the annealing time is 1-3 hours.

[0019] Step 1.3: Transfer the CoCrMo alloy billet to a press for a second forging to further obtain a billet. Then, place the obtained billet into a heat treatment furnace for a second annealing treatment. The second forging process involves several forging passes until the total deformation reaches 25-45%, with the deformation of each adjacent forging pass being 2-4%. The annealing temperature for the second annealing treatment is 1100-1180℃, and the annealing time is 1-3 hours.

[0020] Step 1.4: Transfer the CoCrMo alloy billet to a press for a third forging to further obtain a billet. Then, place the obtained billet into a heat treatment furnace for a third annealing treatment. The third forging process involves several forging passes until the total deformation reaches 10-30%, with the deformation of each adjacent forging pass being 2-4%. The annealing temperature for the third annealing treatment is 1120-1200℃, and the annealing time is 1-4 hours.

[0021] Step 1.5: Transfer the CoCrMo alloy billet to a precision forging machine for radial forging to obtain a square billet. Then, place the obtained square billet into a heat treatment furnace for a fourth annealing treatment. The radial forging process involves five passes of radial forging, with a deformation of 6-12% between adjacent passes. The annealing temperature for the fourth annealing treatment is 1150-1220℃, and the annealing time is 1-4 hours.

[0022] Step 1.6: Transfer the CoCrMo alloy billet to a hot rolling mill for at least two hot rolling operations to obtain bars. The deformation amount of each of the two adjacent hot rolling operations is 10-30%. After the entire hot rolling process is completed, the CoCrMo alloy bars are finally obtained.

[0023] In any of the above schemes, it is preferred that, in step one, the chemical composition of the CoCrMo alloy rod includes, by mass percentage, Cr 26.0-30.0wt%, Mo 5.0-7.0wt%, Ni≤1.0wt%, C≤0.35wt%, Fe≤0.75wt%, Si≤1.0wt%, Mn≤1.0wt%, N≤0.35wt%, with the balance being Co.

[0024] The CoCrMo alloy rod has a diameter of 11-13 mm; the grain size of the CoCrMo alloy rod is grade 11; the tensile strength in the processed state is 1376-1410 MPa, the yield strength is 980-1100 MPa, the elongation at section is not less than 44.5%, and the reduction of area is not less than 39.5%.

[0025] In any of the above schemes, it is preferred that, in step two, the annealing temperature of the CoCrMo alloy bar is 950-1080℃ and the annealing time is 20-120min, and no protective atmosphere is required during the annealing process.

[0026] In any of the above schemes, it is preferred that in step three, the rounding dimension is 10mm, that is, the diameter of the CoCrMo alloy rod after correction is 10mm; and the peeling thickness does not exceed 0.3mm.

[0027] In any of the above schemes, preferably, in step four, the deformation amount of the first cold drawing is 20-30%; the vacuum degree of the first vacuum annealing treatment does not exceed 0.01 Pa, the annealing temperature is 950-1080℃, and the annealing time is 30-90 min; the flow rate of argon gas introduced in the first gas cooling is 50-80 m³ / min. 3 / h, air cooling time is 15-20min.

[0028] In any of the above schemes, preferably, in step five, the deformation amount of the second cold drawing is 20-30%; the vacuum degree of the second vacuum annealing treatment does not exceed 0.01 Pa, the annealing temperature is 950-1080℃, and the annealing time is 30-90 min; the flow rate of argon gas introduced in the second gas cooling is 50-80 m³ / min. 3 / h, air cooling time is 15-20min.

[0029] In any of the above embodiments, preferably, in step six, the deformation amount of the third cold drawing is 70-80% of the deformation amount of the second cold drawing; the vacuum degree of the third vacuum annealing treatment does not exceed 0.01 Pa, the annealing temperature is 950-1080℃, and the annealing time is 30-90 min; the flow rate of argon gas introduced in the third gas cooling is 50-80 m³ / min. 3 / h, air cooling time is 15-20min; the diameter of the wire obtained by the third cold drawing is not less than 6mm.

[0030] In any of the above schemes, it is preferred that in step seven, the wire is transferred to a drawing machine for several subsequent cold draws, and the deformation amount of each cold draw is 60-65% of the deformation amount of the previous cold draw.

[0031] After each cold drawing, the wire was subjected to vacuum annealing and argon gas cooling in sequence. Except for the last cold drawing, the vacuum degree of the vacuum annealing after each cold drawing did not exceed 0.01 Pa, the annealing temperature was 950-1080℃, the annealing time was 30-90 min, and the argon gas flow rate was 50-80 m³ / min. 3 / h, air cooling time is 15-20min.

[0032] The vacuum degree of the final cold drawing followed by vacuum annealing should not exceed 0.01 Pa, the annealing temperature should be 400-800℃, the annealing time should be 2-6 hours, and the argon gas flow rate should be 50-80 m³ / h. 3 / h, air cooling time is 7-10min.

[0033] In any of the above schemes, preferably, in step seven, the diameter of the final CoCrMo alloy wire obtained does not exceed 6 mm; the grain size of the final CoCrMo alloy wire reaches grade 12; the tensile strength of the processed state is 1500-1600 MPa, the yield strength is 1000-1200 MPa, the elongation at section is not less than 35%, and the reduction of area is not less than 32%; and the tensile strength of the annealed state is 1500-1600 MPa, the yield strength is 1000-1200 MPa, the elongation at section is not less than 45%, and the reduction of area is not less than 40%.

[0034] The CoCrMo alloy wire of the present invention is further prepared based on the preparation method of modified CoCrMo alloy rod in patent application No. 202410966366.8.

[0035] CoCrMo alloy bars were prepared by a combination of forging, radial forging, and hot rolling. The multi-pass forging and multi-directional radial pressure plastic deformation resulted in more uniform and stable deformation; the shorter overall deformation time and smaller temperature drop reduced deformation cracking; the larger overall deformation amount led to significant grain refinement, improving strength and toughness; and the uniform and fine microstructure of the CoCrMo alloy bars provided a good microstructure foundation for subsequent deformation.

[0036] In the preparation of CoCrMo alloy wire, the process involves two large-deformation cold drawing stages, one medium-deformation cold drawing stage, and several small-deformation cold drawing stages. Each cold drawing stage requires medium-to-high temperature heat treatment and argon cooling. Large-deformation cold drawing refines the grain size, while annealing at a temperature above the recrystallization temperature and below the grain growth temperature removes work hardening and inhibits grain growth. Compared to hot rolling, the cold drawing process of this invention produces wires with more regular dimensions, reduces surface finishing, increases yield, and lowers costs. The same batch of material can be used to produce wires of different sizes and smaller specifications.

[0037] In the process of preparing CoCrMo alloy wire, after the final cold drawing, a low-temperature heat treatment is adopted. This not only avoids the decrease in strength after high-temperature heat treatment, but also further removes the residual stress accumulated after cold drawing, and reduces the amount of springback deformation in subsequent processing.

[0038] In this invention, the basic material for preparing CoCrMo alloy wire, namely CoCrMo alloy rod, must meet the following basic parameters: the diameter of the CoCrMo alloy rod is 11-13 mm, the grain size is not lower than grade 11, the tensile strength in the processed state is 1376-1410 MPa, the yield strength is 980-1100 MPa, the elongation at section is not lower than 44.5%, and the reduction of area is not lower than 39.5%; the diameter of the CoCrMo alloy rod after modification is 10 mm. In the process of preparing CoCrMo alloy wire, the wire diameter obtained after the third cold drawing is not less than 6 mm. Based on this, cold drawing continues to be performed to produce wires of any size with a diameter not exceeding 6 mm, as required.

[0039] The method for preparing the modified CoCrMo alloy wire of the present invention involves, based on a CoCrMo alloy rod with a certain grain size, mechanical properties, and geometric dimensions, performing two large deformation cold drawing processes, one medium deformation cold drawing process, several small deformation cold drawing processes, and several medium- and high-temperature heat treatments and argon cooling processes, and finally performing low-temperature heat treatment to obtain the wire. No cracking occurred in the wire at any stage of the cold drawing process. The final CoCrMo alloy wire has fine grains, uniform and stable microstructure, and a grain size of grade 12. The tensile strength in the processed state is 1500-1600 MPa, the yield strength is 1000-1200 MPa, the elongation at break is not less than 35%, and the reduction of area is not less than 32%. The tensile strength in the annealed state is 1500-1600 MPa, the yield strength is 1000-1200 MPa, the elongation at break is not less than 45%, and the reduction of area is not less than 40%. This meets the requirements of the biomedical field for the microstructure and properties of CoCrMo alloys, as well as the demand for smaller size wires. Attached Figure Description

[0040] Figure 1 A flowchart of a preferred embodiment of the method for preparing modified CoCrMo alloy wire according to the present invention;

[0041] Figure 2 for Figure 1 A photograph of the final CoCrMo alloy wire obtained in the illustrated embodiment;

[0042] Figure 3 for Figure 1 The microstructure of the final processed CoCrMo alloy wire obtained in the embodiment shown is illustrated.

[0043] Figure 4 for Figure 1 The microstructure of the CoCrMo alloy wire obtained in the final annealed state in the illustrated embodiment is shown in the photograph.

[0044] Figure 5This is a photograph of the microstructure of the CoCrMo alloy wire in the processed state, obtained according to another preferred embodiment of the preparation method of the modified CoCrMo alloy wire of the present invention.

[0045] Figure 6 for Figure 5 The microstructure of the CoCrMo alloy wire obtained in the final annealed state in the illustrated embodiment is shown in the photograph.

[0046] Figure 7 This is a photograph of the microstructure of the CoCrMo alloy wire in the processed state, obtained according to another preferred embodiment of the preparation method of the modified CoCrMo alloy wire of the present invention.

[0047] Figure 8 for Figure 7 The microstructure of the CoCrMo alloy wire obtained in the final annealed state in the illustrated embodiment is shown in the photograph. Detailed Implementation

[0048] To further understand the invention, the following detailed description of the invention will be provided in conjunction with specific embodiments.

[0049] Example 1:

[0050] like Figure 1 As shown, in a preferred embodiment of the method for preparing modified CoCrMo alloy wire according to the present invention, the preparation method includes the following steps in sequence:

[0051] Step 1: Prepare CoCrMo alloy bars with certain grain size, mechanical properties and geometric dimensions according to the designed forging-radial forging-hot rolling method, and use the CoCrMo alloy bars as the base material for preparing CoCrMo alloy wires;

[0052] Step 2: Place the CoCrMo alloy bar into a heat treatment furnace for annealing.

[0053] Step 3: Transfer the annealed CoCrMo alloy bar to the drawing machine, pre-cool and draw it according to the designed rounding dimensions to correct the shape and size of the CoCrMo alloy bar so that its cross-section is circular. Then, peel the rounded CoCrMo alloy bar according to the designed peeling thickness.

[0054] Step 4: After the peeling process is completed, the CoCrMo alloy bar is transferred to the drawing machine for the first cold drawing to obtain wire. The wire obtained by the first cold drawing is placed in a vacuum heat treatment furnace for the first vacuum annealing treatment. Then, argon gas is introduced into the vacuum heat treatment furnace to perform the first gas cooling of the wire.

[0055] Step 5: After the first air cooling is completed, the wire is transferred to the drawing machine for a second cold drawing and further processed into wire. The wire obtained from the second cold drawing is placed in a vacuum heat treatment furnace for a second vacuum annealing treatment. Then, argon gas is introduced into the vacuum heat treatment furnace to perform a second air cooling on the wire.

[0056] Step 6: After the second air cooling is completed, the wire is transferred to the drawing machine for a third cold drawing and further processed into wire. The wire obtained by the third cold drawing is placed in a vacuum heat treatment furnace for a third vacuum annealing treatment. Then, argon gas is introduced into the vacuum heat treatment furnace to perform a third air cooling on the wire.

[0057] Step 7: After the third air cooling is completed, the wire is transferred to the drawing machine for several subsequent cold drawing and further wire production until the wire diameter reaches the required size. After each cold drawing, the wire is placed in a vacuum heat treatment furnace for vacuum annealing. Then, argon gas is introduced into the vacuum heat treatment furnace to air cool the wire, and finally, the modified CoCrMo alloy wire is obtained.

[0058] Step 8: Transfer the finally obtained deformed CoCrMo alloy wire to a straightening machine for straightening, and then cut, package, and store it according to the required dimensions.

[0059] In step one, the preparation method of the CoCrMo alloy rod includes the following steps:

[0060] Step 1.1: Prepare CoCrMo alloy ingots using a duplex melting method and then homogenize them;

[0061] Step 1.2: Transfer the CoCrMo alloy ingot to a press for the first forging to obtain a billet. Then, place the billet in a heat treatment furnace for the first annealing treatment. The first forging process involves several forging passes until the total deformation reaches 8-20%, with the deformation between adjacent forging passes being 1-2%. The annealing temperature for the first annealing treatment is 1150-1220℃, and the annealing time is 1-3 hours.

[0062] Step 1.3: Transfer the CoCrMo alloy billet to a press for a second forging to further obtain a billet. Then, place the obtained billet into a heat treatment furnace for a second annealing treatment. The second forging process involves several forging passes until the total deformation reaches 25-45%, with the deformation of each adjacent forging pass being 2-4%. The annealing temperature for the second annealing treatment is 1100-1180℃, and the annealing time is 1-3 hours.

[0063] Step 1.4: Transfer the CoCrMo alloy billet to a press for a third forging to further obtain a billet. Then, place the obtained billet into a heat treatment furnace for a third annealing treatment. The third forging process involves several forging passes until the total deformation reaches 10-30%, with the deformation of each adjacent forging pass being 2-4%. The annealing temperature for the third annealing treatment is 1120-1200℃, and the annealing time is 1-4 hours.

[0064] Step 1.5: Transfer the CoCrMo alloy billet to a precision forging machine for radial forging to obtain a square billet. Then, place the obtained square billet into a heat treatment furnace for a fourth annealing treatment. The radial forging process involves five passes of radial forging, with a deformation of 6-12% between adjacent passes. The annealing temperature for the fourth annealing treatment is 1150-1220℃, and the annealing time is 1-4 hours.

[0065] Step 1.6: Transfer the CoCrMo alloy billet to a hot rolling mill for at least two hot rolling operations to obtain bars. The deformation amount of each of the two adjacent hot rolling operations is 10-30%. After the entire hot rolling process is completed, the CoCrMo alloy bars are finally obtained.

[0066] In step one, the chemical composition of the CoCrMo alloy rod, by mass percentage, includes Cr 28.0wt%, Mo 6.0wt%, Ni 1.0wt%, C 0.35wt%, Fe 0.75wt%, Si 1.0wt%, Mn 1.0wt%, N 0.35wt%, with the balance being Co. The CoCrMo alloy ingot is prepared using a dual-melting process, namely, vacuum induction melting and protective atmosphere electroslag remelting. The key parameters for the vacuum induction melting process are: a vacuum pressure of 30 Pa during the cleaning stage, a vacuum pressure of 10 Pa during the refining stage, and a pouring temperature of 1520℃. The key parameters for the protective atmosphere electroslag remelting process are: a melting rate of 4.5 kg / min, an argon flow rate of 5 L / min, and a feeding weight of 85 kg.

[0067] The homogenization process for CoCrMo alloy ingots is as follows: the CoCrMo alloy ingots are placed in a heat treatment furnace and heated from room temperature to 500°C at a rate of 8°C / min, and held for 1.5 hours; the temperature is then increased from 500°C to 900°C at a rate of 8°C / min, and held for 1.5 hours; the temperature is then increased from 900°C to 1200°C at a rate of 8°C / min, and held for 4 hours; no protective atmosphere is required during the homogenization process.

[0068] The process for the first forging is as follows: The CoCrMo alloy ingot is placed on the platform of a press. The press head performs the first forging pass from one end of the ingot to the other. After the first forging pass, the ingot is rotated 60° axially, and the press head continues to perform the second forging pass from one end to the other. After the second forging pass, the ingot is rotated 60° axially again, and the press head continues to perform the third forging pass from one end to the other, and so on, until the total deformation reaches 12%, thus completing the first forging and producing a billet. The deformation of each adjacent forging pass is 1.5%. The process for the first annealing is as follows: annealing temperature 1180℃, annealing time 2 hours.

[0069] The process for the second forging is as follows: the billet is placed horizontally on the platform of the press. The press head performs the first forging from one end of the billet to the other. After the first forging, the billet is rotated 60° axially, and the press head continues to perform the second forging from one end of the billet to the other. After the second forging, the billet is rotated 60° axially again, and the press head continues to perform the third forging from one end of the billet to the other, and so on, until the total deformation reaches 42%, thus completing the second forging and further producing the billet. The deformation of each of the two adjacent forging passes is 3%. The process for the second annealing is as follows: annealing temperature 1140℃, annealing time 2 hours.

[0070] The process for the third forging is as follows: the billet is placed horizontally on the platform of the press. The press head performs the first forging from one end of the billet to the other. After the first forging, the billet is rotated 60° axially, and the press head continues to perform the second forging from one end of the billet to the other. After the second forging, the billet is rotated 60° axially again, and the press head continues to perform the third forging from one end of the billet to the other, and so on, until the total deformation reaches 19%, thus completing the third forging and further producing the billet. The deformation of each of the two adjacent forging passes is 3%. The process for the third annealing is as follows: annealing temperature 1160℃, annealing time 2 hours.

[0071] The radial forging process is as follows: The billet is mounted on a precision forging machine. The forging hammer performs a first radial forging from one end of the billet to the other, producing an elliptical billet. After the first radial forging, the forging hammer performs a second radial forging from one end of the elliptical billet to the other, producing a circular billet. After the second radial forging, the forging hammer performs a third radial forging from one end of the circular billet to the other, producing another elliptical billet. After the third radial forging, the forging hammer performs a fourth radial forging from one end of the elliptical billet to the other, producing another circular billet. After the fourth radial forging, the forging hammer performs a fifth radial forging from one end of the circular billet to the other, producing a square billet. The deformation amount for each adjacent radial forging is 9%. The fourth annealing process is as follows: annealing temperature 1180℃, annealing time 2 hours.

[0072] The hot rolling process is as follows: at least two hot rolling cycles, with a deformation of 10% for each of the two adjacent hot rolling cycles.

[0073] The final CoCrMo alloy rods have a diameter of 11-13 mm. The grain size of the CoCrMo alloy rods is grade 11, and the tensile strength in the processed state is 1376-1410 MPa, the yield strength is 980-1100 MPa, the elongation at section is not less than 44.5%, and the reduction of area is not less than 39.5%.

[0074] In step two, the annealing temperature of the CoCrMo alloy bar is 1015℃ and the annealing time is 70 min. No protective atmosphere is required during the annealing process.

[0075] In step three, the rounding dimension is 10mm, that is, the diameter of the CoCrMo alloy rod after correction is 10mm; the peeling thickness does not exceed 0.3mm.

[0076] In step four, the deformation amount of the first cold drawing is 25%; the vacuum degree of the first vacuum annealing treatment does not exceed 0.01 Pa, the annealing temperature is 1015℃, and the annealing time is 60 min; the flow rate of argon gas introduced in the first gas cooling is 65 m³ / min. 3 / h, air cooling time is 17.5min.

[0077] In step five, the deformation amount of the second cold drawing is 25%; the vacuum degree of the second vacuum annealing treatment does not exceed 0.01 Pa, the annealing temperature is 1015℃, and the annealing time is 60 min; the flow rate of argon gas introduced in the second gas cooling is 65 m³ / min. 3 / h, air cooling time is 17.5min.

[0078] In step six, the deformation amount of the third cold drawing is 75% of the deformation amount of the second cold drawing; the vacuum degree of the third vacuum annealing treatment does not exceed 0.01 Pa, the annealing temperature is 1015℃, and the annealing time is 60 min; the flow rate of argon gas introduced in the third gas cooling is 65 m³ / min. 3 / h, air cooling time is 17.5min; the diameter of the wire obtained by the third cold drawing is not less than 6mm.

[0079] In step seven, the wire is transferred to a drawing machine for several subsequent cold draws, with each cold draw involving 62.5% of the deformation of the previous cold draw. After each cold draw, the wire is sequentially subjected to vacuum annealing and argon gas cooling. Except for the final cold draw, the vacuum degree after each cold draw and vacuum annealing is no more than 0.01 Pa, the annealing temperature is 1015℃, the annealing time is 60 min, and the argon gas flow rate is 65 m³ / min. 3 The cooling time was 17.5 min. After the final cold drawing, the vacuum degree of the vacuum annealing treatment did not exceed 0.01 Pa, the annealing temperature was 600℃, the annealing time was 4 h, and the argon gas flow rate was 65 m³ / h. 3 / h, air cooling time is 8.5min.

[0080] In step seven, the diameter of the final CoCrMo alloy wire obtained shall not exceed 6 mm; the grain size of the final CoCrMo alloy wire shall reach grade 12; the tensile strength of the processed state shall be 1500-1600 MPa, the yield strength shall be 1000-1200 MPa, the elongation at section shall not be less than 35%, and the reduction of area shall not be less than 32%; the tensile strength of the annealed state shall be 1500-1600 MPa, the yield strength shall be 1000-1200 MPa, the elongation at section shall not be less than 45%, and the reduction of area shall not be less than 40%.

[0081] The furnace chamber volume of the vacuum heat treatment furnace used in this embodiment is 1m³. 3 It can heat-treat 200 kg of raw materials. In this embodiment, the prepared CoCrMo alloy wire is as follows: Figure 2 As shown, its diameter is 5 mm, and the final microstructure of the CoCrMo alloy wire in the processed state is as follows. Figure 3 As shown, the microstructure in the annealed state is as follows Figure 4 As shown.

[0082] The method for preparing modified CoCrMo alloy wire in this embodiment involves, based on CoCrMo alloy rods with certain grain size, mechanical properties, and geometric dimensions, undergoing two large-deformation cold drawing processes, one medium-deformation cold drawing process, several small-deformation cold drawing processes, and several medium-to-high temperature heat treatments followed by argon cooling, finally followed by low-temperature heat treatment. No cracking occurred in the wire at any stage of the entire cold drawing process. The final prepared CoCrMo alloy wire has fine grains, a uniform and stable microstructure, a grain size of grade 12, and good mechanical properties in both the processed and annealed states, meeting the requirements of the biomedical field for the microstructure and properties of CoCrMo alloys, as well as the demand for smaller-sized wires.

[0083] Example 2:

[0084] Another preferred embodiment of the method for preparing modified CoCrMo alloy wire according to the present invention has the same process flow, process parameters, technical principles, and beneficial effects as Embodiment 1, except that:

[0085] In step one, the chemical composition of the CoCrMo alloy rod, by mass percentage, includes Cr 26.0wt%, Mo 7.0wt%, Ni 1.0wt%, C 0.35wt%, Fe 0.75wt%, Si 1.0wt%, Mn 1.0wt%, N 0.35wt%, with the balance being Co. The CoCrMo alloy ingot is prepared by duplex melting. The key parameters of the vacuum induction melting process are: a cleaning vacuum pressure of 30Pa, a refining stage vacuum pressure of 10Pa, and a pouring temperature of 1510℃; the key parameters of the protective atmosphere electroslag remelting process are: a melting rate of 4.5kg / min, an argon flow rate of 5L / min, and a feeding weight of 85kg.

[0086] The homogenization process for CoCrMo alloy ingots is as follows: the CoCrMo alloy ingots are placed in a heat treatment furnace and heated from room temperature to 500°C at a rate of 5°C / min, and held for 2 hours; the temperature is then increased from 500°C to 900°C at a rate of 5°C / min, and held for 2 hours; the temperature is then increased from 900°C to 1150°C at a rate of 5°C / min, and held for 6 hours; no protective atmosphere is required during the homogenization process.

[0087] The key parameters for the first forging process are: to forge the CoCrMo alloy ingot several times until the total deformation reaches 12%, with the deformation of each adjacent forging pass being 1.2%. The process parameters for the first annealing treatment are: annealing temperature 1180℃, annealing time 3h.

[0088] The key parameters for the second forging process are: the CoCrMo alloy billet is forged several times until the total deformation reaches 42%, and the deformation of each adjacent forging pass is 4%. The process parameters for the second annealing treatment are: annealing temperature 1160℃, annealing time 3h.

[0089] The key parameters for the third forging process are: to forge the CoCrMo alloy billet several times until the total deformation reaches 19%, with the deformation of each adjacent forging pass being 2%. The process parameters for the third annealing treatment are: annealing temperature 1170℃, annealing time 4h.

[0090] The key parameters for the radial forging process are: the CoCrMo alloy billet is subjected to five radial forging passes to obtain a square billet, and the deformation amount of each adjacent radial forging pass is 9%. The process parameters for the fourth annealing treatment are: annealing temperature 1150℃, annealing time 4h.

[0091] The hot rolling process is as follows: at least two hot rolling cycles, with a deformation of 10% for each of the two adjacent hot rolling cycles.

[0092] The final CoCrMo alloy rods have a diameter of 11-13 mm. The grain size of the CoCrMo alloy rods is grade 11, and the tensile strength in the processed state is 1376-1410 MPa, the yield strength is 980-1100 MPa, the elongation at section is not less than 44.5%, and the reduction of area is not less than 39.5%.

[0093] In step two, the annealing temperature of the CoCrMo alloy bar is 950℃ and the annealing time is 120min. No protective atmosphere is required during the annealing process.

[0094] In step three, the rounding dimension is 10mm, that is, the diameter of the CoCrMo alloy rod after correction is 10mm; the peeling thickness does not exceed 0.3mm.

[0095] In step four, the deformation amount of the first cold drawing is 20%; the vacuum degree of the first vacuum annealing treatment does not exceed 0.01 Pa, the annealing temperature is 950℃, and the annealing time is 90 min; the flow rate of argon gas introduced in the first gas cooling is 50 m³ / min. 3 / h, air cooling time is 20min.

[0096] In step five, the deformation amount of the second cold drawing is 20%; the vacuum degree of the second vacuum annealing treatment does not exceed 0.01 Pa, the annealing temperature is 950℃, and the annealing time is 90 min; the flow rate of argon gas introduced in the second gas cooling is 50 m³ / min. 3 / h, air cooling time is 20min.

[0097] In step six, the deformation amount of the third cold drawing is 70% of the deformation amount of the second cold drawing; the vacuum degree of the third vacuum annealing treatment does not exceed 0.01 Pa, the annealing temperature is 950℃, and the annealing time is 90 min; the flow rate of argon gas introduced in the third gas cooling is 50 m³ / min. 3 / h, air cooling time is 20min; the diameter of the wire obtained by the third cold drawing is not less than 6mm.

[0098] In step seven, the wire is transferred to a drawing machine for several subsequent cold draws, with each cold draw involving 60% of the deformation of the previous cold draw. After each cold draw, the wire is subjected to vacuum annealing and argon gas cooling. Except for the final cold draw, the vacuum degree after each cold draw and the vacuum annealing are all no more than 0.01 Pa, the annealing temperature is 950℃, the annealing time is 90 min, and the argon gas flow rate is 50 m³ / min. 3 The cooling time was 20 minutes per hour. After the final cold drawing, the vacuum degree of the vacuum annealing treatment did not exceed 0.01 Pa, the annealing temperature was 400℃, the annealing time was 6 hours, and the argon gas flow rate was 50 m³ / h. 3 / h, air cooling time is 10min.

[0099] In step seven, the diameter of the final CoCrMo alloy wire obtained shall not exceed 6 mm; the grain size of the final CoCrMo alloy wire shall reach grade 12; the tensile strength of the processed state shall be 1500-1600 MPa, the yield strength shall be 1000-1200 MPa, the elongation at section shall not be less than 35%, and the reduction of area shall not be less than 32%; the tensile strength of the annealed state shall be 1500-1600 MPa, the yield strength shall be 1000-1200 MPa, the elongation at section shall not be less than 45%, and the reduction of area shall not be less than 40%.

[0100] The CoCrMo alloy wire prepared in this embodiment has a diameter of 3 mm, and the final microstructure of the processed CoCrMo alloy wire is as follows. Figure 5 As shown, the microstructure in the annealed state is as follows Figure 6 As shown.

[0101] Example 3:

[0102] Another preferred embodiment of the method for preparing modified CoCrMo alloy wire according to the present invention has the same process flow, process parameters, technical principles, and beneficial effects as Embodiment 1, except that:

[0103] In step one, the chemical composition of the CoCrMo alloy rod, by mass percentage, includes Cr 30.0wt%, Mo 5.0wt%, Ni 1.0wt%, C 0.35wt%, Fe 0.75wt%, Si 1.0wt%, Mn 1.0wt%, N 0.35wt%, with the balance being Co. The CoCrMo alloy ingot is prepared by duplex melting. The key parameters of the vacuum induction melting process are: a clearing vacuum pressure of 30 Pa, a refining stage vacuum pressure of 10 Pa, and a pouring temperature of 1550℃; the key parameters of the protective atmosphere electroslag remelting process are: a melting rate of 4.5 kg / min, an argon flow rate of 5 L / min, and a feeding weight of 85 kg.

[0104] The homogenization process for CoCrMo alloy ingots is as follows: the CoCrMo alloy ingots are placed in a heat treatment furnace and heated from room temperature to 500°C at a rate of 10°C / min, and held for 1 hour; the temperature is then increased from 500°C to 900°C at a rate of 10°C / min, and held for 1 hour; the temperature is then increased from 900°C to 1250°C at a rate of 10°C / min, and held for 1 hour; no protective atmosphere is required during the homogenization process.

[0105] The key parameters for the first forging process are: to forge the CoCrMo alloy ingot several times until the total deformation reaches 12%, with the deformation of each adjacent forging pass being 2%. The process parameters for the first annealing treatment are: annealing temperature 1220℃, annealing time 1 hour.

[0106] The key parameters for the second forging process are: the CoCrMo alloy billet is forged several times until the total deformation reaches 42%, and the deformation of each adjacent forging pass is 4%. The process parameters for the second annealing treatment are: annealing temperature 1180℃, annealing time 1h.

[0107] The key parameters for the third forging process are: the CoCrMo alloy billet is forged several times until the total deformation reaches 19%, and the deformation of each adjacent forging is 3%. The process parameters for the third annealing treatment are: annealing temperature 1200℃, annealing time 1h.

[0108] The key parameters for the radial forging process are: the CoCrMo alloy billet is subjected to five radial forging passes to obtain a square billet, and the deformation amount of each adjacent radial forging pass is 10%. The process parameters for the fourth annealing treatment are: annealing temperature 1220℃, annealing time 1h.

[0109] The hot rolling process is as follows: at least two hot rolling cycles, with a deformation of 15% for each of the two adjacent hot rolling cycles.

[0110] The final CoCrMo alloy rods have a diameter of 11-13 mm. The grain size of the CoCrMo alloy rods is grade 11, and the tensile strength in the processed state is 1376-1410 MPa, the yield strength is 980-1100 MPa, the elongation at section is not less than 44.5%, and the reduction of area is not less than 39.5%.

[0111] In step two, the annealing temperature of the CoCrMo alloy bar is 1080℃ and the annealing time is 20min. No protective atmosphere is required during the annealing process.

[0112] In step three, the rounding dimension is 10mm, that is, the diameter of the CoCrMo alloy rod after correction is 10mm; the peeling thickness does not exceed 0.3mm.

[0113] In step four, the deformation amount of the first cold drawing is 30%; the vacuum degree of the first vacuum annealing treatment does not exceed 0.01 Pa, the annealing temperature is 1080℃, and the annealing time is 30 min; the flow rate of argon gas introduced in the first gas cooling is 80 m³ / min. 3 / h, air cooling time is 15min.

[0114] In step five, the deformation amount of the second cold drawing is 30%; the vacuum degree of the second vacuum annealing treatment does not exceed 0.01 Pa, the annealing temperature is 1080℃, and the annealing time is 30 min; the flow rate of argon gas introduced in the second gas cooling is 80 m³ / min. 3 / h, air cooling time is 15min.

[0115] In step six, the deformation amount of the third cold drawing is 80% of the deformation amount of the second cold drawing; the vacuum degree of the third vacuum annealing treatment does not exceed 0.01 Pa, the annealing temperature is 1080℃, and the annealing time is 30 min; the flow rate of argon gas introduced in the third gas cooling is 80 m³ / min. 3 / h, air cooling time is 15min; the diameter of the wire obtained by the third cold drawing is not less than 6mm.

[0116] In step seven, the wire is transferred to a drawing machine for several subsequent cold draws, with each cold draw involving 65% of the deformation of the previous cold draw. After each cold draw, the wire is sequentially subjected to vacuum annealing and argon gas cooling. Except for the final cold draw, the vacuum degree after each cold draw and vacuum annealing is no more than 0.01 Pa, the annealing temperature is 1080℃, the annealing time is 30 min, and the argon gas flow rate is 80 m³ / min. 3 The cooling time was 15 minutes per hour. After the final cold drawing, the vacuum degree of the vacuum annealing treatment did not exceed 0.01 Pa, the annealing temperature was 800℃, the annealing time was 2 hours, and the argon gas flow rate was 80 m³ / h. 3 / h, air cooling time is 7min.

[0117] In step seven, the diameter of the final CoCrMo alloy wire obtained shall not exceed 6 mm; the grain size of the final CoCrMo alloy wire shall reach grade 12; the tensile strength of the processed state shall be 1500-1600 MPa, the yield strength shall be 1000-1200 MPa, the elongation at section shall not be less than 35%, and the reduction of area shall not be less than 32%; the tensile strength of the annealed state shall be 1500-1600 MPa, the yield strength shall be 1000-1200 MPa, the elongation at section shall not be less than 45%, and the reduction of area shall not be less than 40%.

[0118] The CoCrMo alloy wire prepared in this embodiment has a diameter of 4 mm, and the final microstructure of the processed CoCrMo alloy wire is as follows. Figure 7 As shown, the microstructure in the annealed state is as follows Figure 8 As shown.

[0119] Special Note: The technical solution of this invention involves numerous parameters, and the synergistic effects between these parameters must be comprehensively considered to achieve the beneficial effects and significant progress of this invention. Furthermore, the value ranges of each parameter in the technical solution were obtained through extensive experimentation. For each parameter and the combinations thereof, the inventors have recorded a large amount of experimental data; however, due to space limitations, the specific experimental data is not disclosed here.

[0120] It will be readily understood by those skilled in the art that this invention includes any combination of the inventive description and specific embodiments outlined in the foregoing specification and the various parts shown in the accompanying drawings. Due to space limitations and for the sake of brevity, not all of these combinations have been described in detail. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for preparing a modified CoCrMo alloy wire, characterized in that: The preparation method includes the following steps in sequence: Step 1: Prepare CoCrMo alloy bars with certain grain size, mechanical properties and geometric dimensions according to the designed forging-radial forging-hot rolling method, and use the CoCrMo alloy bars as the base material for preparing CoCrMo alloy wires; Step 2: Place the CoCrMo alloy bar into a heat treatment furnace for annealing. Step 3: Transfer the annealed CoCrMo alloy bar to the drawing machine, pre-cool and draw it according to the designed rounding dimensions to correct the shape and size of the CoCrMo alloy bar so that its cross-section is circular. Then, peel the rounded CoCrMo alloy bar according to the designed peeling thickness. Step 4: After the peeling process is completed, the CoCrMo alloy bar is transferred to the drawing machine for the first cold drawing to obtain wire. The wire obtained by the first cold drawing is placed in a vacuum heat treatment furnace for the first vacuum annealing treatment. Then, argon gas is introduced into the vacuum heat treatment furnace to perform the first gas cooling of the wire. Step 5: After the first air cooling is completed, the wire is transferred to the drawing machine for a second cold drawing and further processed into wire. The wire obtained from the second cold drawing is placed in a vacuum heat treatment furnace for a second vacuum annealing treatment. Then, argon gas is introduced into the vacuum heat treatment furnace to perform a second air cooling on the wire. Step 6: After the second air cooling is completed, the wire is transferred to the drawing machine for a third cold drawing and further processed into wire. The wire obtained by the third cold drawing is placed in a vacuum heat treatment furnace for a third vacuum annealing treatment. Then, argon gas is introduced into the vacuum heat treatment furnace to perform a third air cooling on the wire. Step 7: After the third air cooling is completed, the wire is transferred to the drawing machine for several subsequent cold drawing and further wire production until the wire diameter reaches the required size. After each cold drawing, the wire is placed in a vacuum heat treatment furnace for vacuum annealing. Then, argon gas is introduced into the vacuum heat treatment furnace to air cool the wire, and finally, the modified CoCrMo alloy wire is obtained. Step 8: Transfer the finally obtained deformed CoCrMo alloy wire to a straightening machine for straightening, and then cut, package, and store it according to the required dimensions.

2. The method for preparing the modified CoCrMo alloy wire according to claim 1, characterized in that: In step one, the preparation method of the CoCrMo alloy rod includes the following steps: Step 1.1: Prepare CoCrMo alloy ingots using a duplex melting method and then homogenize them; Step 1.2: Transfer the CoCrMo alloy ingot to a press for the first forging to obtain a billet. Then, place the billet in a heat treatment furnace for the first annealing treatment. The first forging process involves several forging passes until the total deformation reaches 8-20%, with the deformation between adjacent forging passes being 1-2%. The annealing temperature for the first annealing treatment is 1150-1220℃, and the annealing time is 1-3 hours. Step 1.3: Transfer the CoCrMo alloy billet to a press for a second forging to further obtain a billet. Then, place the obtained billet into a heat treatment furnace for a second annealing treatment. The second forging process involves several forging passes until the total deformation reaches 25-45%, with the deformation of each adjacent forging pass being 2-4%. The annealing temperature for the second annealing treatment is 1100-1180℃, and the annealing time is 1-3 hours. Step 1.4: Transfer the CoCrMo alloy billet to a press for a third forging to further obtain a billet. Then, place the obtained billet into a heat treatment furnace for a third annealing treatment. The third forging process involves several forging passes until the total deformation reaches 10-30%, with the deformation of each adjacent forging pass being 2-4%. The annealing temperature for the third annealing treatment is 1120-1200℃, and the annealing time is 1-4 hours. Step 1.5: Transfer the CoCrMo alloy billet to a precision forging machine for radial forging to obtain a square billet. Then, place the obtained square billet into a heat treatment furnace for a fourth annealing treatment. The radial forging process involves five passes of radial forging, with a deformation of 6-12% between adjacent passes. The annealing temperature for the fourth annealing treatment is 1150-1220℃, and the annealing time is 1-4 hours. Step 1.6: Transfer the CoCrMo alloy billet to a hot rolling mill for at least two hot rolling operations to obtain bars. The deformation amount of each of the two adjacent hot rolling operations is 10-30%. After the entire hot rolling process is completed, the CoCrMo alloy bars are finally obtained.

3. The method for preparing the modified CoCrMo alloy wire according to claim 2, characterized in that: In step one, the chemical composition of the CoCrMo alloy rod, by mass percentage, includes Cr 26.0-30.0wt%, Mo 5.0-7.0wt%, Ni≤1.0wt%, C≤0.35wt%, Fe≤0.75wt%, Si≤1.0wt%, Mn≤1.0wt%, N≤0.35wt%, with the balance being Co; The CoCrMo alloy rod has a diameter of 11-13 mm; the grain size of the CoCrMo alloy rod is grade 11; the tensile strength in the processed state is 1376-1410 MPa, the yield strength is 980-1100 MPa, the elongation at section is not less than 44.5%, and the reduction of area is not less than 39.5%.

4. The method for preparing the modified CoCrMo alloy wire according to claim 3, characterized in that: In step two, the annealing temperature of the CoCrMo alloy bar is 950-1080℃ and the annealing time is 20-120min. No protective atmosphere is required during the annealing process.

5. The method for preparing the modified CoCrMo alloy wire according to claim 4, characterized in that: In step three, the rounding dimension is 10mm, that is, the diameter of the CoCrMo alloy rod after correction is 10mm; the peeling thickness does not exceed 0.3mm.

6. The method for preparing the modified CoCrMo alloy wire according to claim 5, characterized in that: In step four, the deformation amount of the first cold drawing is 20-30%; the vacuum degree of the first vacuum annealing treatment does not exceed 0.01 Pa, the annealing temperature is 950-1080℃, and the annealing time is 30-90 min; the flow rate of argon gas introduced in the first gas cooling is 50-80 m³ / min. 3 / h, air cooling time is 15-20min.

7. The method for preparing the modified CoCrMo alloy wire according to claim 6, characterized in that: In step five, the deformation amount of the second cold drawing is 20-30%; the vacuum degree of the second vacuum annealing treatment does not exceed 0.01 Pa, the annealing temperature is 950-1080℃, and the annealing time is 30-90 min; the flow rate of argon gas introduced in the second gas cooling is 50-80 m³ / min. 3 / h, air cooling time is 15-20min.

8. The method for preparing the modified CoCrMo alloy wire according to claim 7, characterized in that: In step six, the deformation amount of the third cold drawing is 70-80% of the deformation amount of the second cold drawing; the vacuum degree of the third vacuum annealing treatment does not exceed 0.01 Pa, the annealing temperature is 950-1080℃, and the annealing time is 30-90 min; the flow rate of argon gas introduced in the third gas cooling is 50-80 m³ / min. 3 / h, air cooling time is 15-20min; the diameter of the wire obtained by the third cold drawing is not less than 6mm.

9. The method for preparing the modified CoCrMo alloy wire according to claim 8, characterized in that: In step seven, the wire is transferred to a drawing machine for several subsequent cold draws, with the deformation amount of each cold draw being 60-65% of the deformation amount of the previous cold draw. After each cold drawing, the wire was subjected to vacuum annealing and argon gas cooling in sequence. Except for the last cold drawing, the vacuum degree of the vacuum annealing after each cold drawing did not exceed 0.01 Pa, the annealing temperature was 950-1080℃, the annealing time was 30-90 min, and the argon gas flow rate was 50-80 m³ / min. 3 / h, air cooling time is 15-20min; The vacuum degree of the final cold drawing followed by vacuum annealing should not exceed 0.01 Pa, the annealing temperature should be 400-800℃, the annealing time should be 2-6 h, and the argon gas flow rate should be 50-80 m³ / h. 3 / h, air cooling time is 7-10min.

10. The method for preparing the modified CoCrMo alloy wire according to claim 9, characterized in that: In step seven, the diameter of the final CoCrMo alloy wire obtained shall not exceed 6 mm; the grain size of the final CoCrMo alloy wire shall reach grade 12; the tensile strength of the processed state shall be 1500-1600 MPa, the yield strength shall be 1000-1200 MPa, the elongation at section shall not be less than 35%, and the reduction of area shall not be less than 32%; the tensile strength of the annealed state shall be 1500-1600 MPa, the yield strength shall be 1000-1200 MPa, the elongation at section shall not be less than 45%, and the reduction of area shall not be less than 40%.

Images