WO2023027012A1 - Cobalt-chromium alloy member, and method for producing same and device using same - Google Patents

Abstract

Provided is a cobalt-chromium alloy member suitable for use in medical devices, devices for gas turbines, or devices for other industrial equipment. This cobalt-chromium alloy member comprises a composition that contains, expressed in terms of mass%, 23-32% Ni, 37-48% Co, and 8-12% Mo with the balance being Cr and unavoidable impurities, wherein the composition also satisfies 20 ≤ [Cr%] + [Mo%] + [unavoidable impurities%] ≤ 40. The cobalt-chromium alloy member has a crystal structure composed of the face-centered cubic lattice (fcc), or has a crystal structure composed of the face-centered cubic lattice (fcc) and the hexagonal close-packed lattice (hcp), and has an average crystal grain size of 2-15 µm, a local crystal orientation variation (KAM value) of 0.0-1.0, both inclusive, a tensile strength of 800-1,200 MPa, and an elongation at break of 30-80%.

Description

Cobalt-chromium alloy member, manufacturing method thereof, and device using the same

The present invention provides cobalt chromium that is suitably used for medical devices such as stents, medical tubes, and medical guide wires, devices for gas turbines used in high-temperature and corrosive environments, and devices for other industrial equipment. The present invention relates to an alloy member and its manufacturing method. In particular, the present invention relates to improvements in cobalt-chromium alloy materials that are excellent in corrosion resistance, biocompatibility, high strength, and excellent ductility, and that are suitable for indwelling medical devices.

Metal parts used in medical equipment, especially metal parts implanted in the human body, require metals with excellent corrosion resistance and biocompatibility, as well as high mechanical properties. Stainless steel, nickel-titanium alloys, Cobalt-chromium alloys and the like have been used. As such a biocompatible alloy, for example, a cobalt-chromium alloy for dental casting (JIS T6115) is known, and a nickel-containing alloy is known as a dental stainless steel wire (JIS T6103).

Among cobalt-chromium alloy members, stents are hollow tubular objects intended to expand and maintain stenosed body vessels, and are broadly classified into self-expanding stents and balloon-expanding stents.
A self-expanding stent is fixed to the tip of a catheter and given self-expandability by using a superelastic alloy or shape memory alloy from the catheter at a predetermined position. For example, a nickel-titanium alloy stent is practically used. has been made

A balloon-expandable stent is fixed to a balloon catheter by compressing the diameter of the tube and expands the diameter of the tube by expanding the balloon at a predetermined position. For example, when stenosis occurs in a blood vessel, the stenosis is widened with a balloon catheter and left in place to support the inner wall of the blood vessel from the inside and prevent restenosis. As for the insertion of the stent, the stent is attached to the distal end of the catheter in a reduced diameter state outside the deflated balloon, and is inserted into the blood vessel together with the balloon portion. After the balloon portion is positioned at the stenosis site, the stent is expanded by inflating the balloon portion, and the stent is left in the expanded state of the stenosis portion, and the balloon catheter is withdrawn.
As alloys for balloon expandable stents, ASTM F90-14 (Co-20Cr-15W-10Ni alloy (L605 alloy)), ASTM F562-13 (Co-20Cr-10Mo-35Ni alloy (MP35N alloy)), and SUS316L are used as surgical implant materials. known (see Non-Patent Documents 1, 3, and 4).

On the other hand, fracture of implanted metal in the field of orthopedic surgery and early fracture of stents in the field of cardiovascular medicine have been reported, and there is a demand for metal members with better fatigue properties. We have developed an alloy with improved low cycle fatigue properties compared to L605 (Co-20Cr-15W-10Ni) alloy and MP35N (Co-20Cr-10Mo-35Ni) alloy, which are most commonly used as coronary stent materials. has been proposed (see Patent Document 1). The composition of this alloy is mass %, Cr is 10 to 27%, Mo is 3 to 12%, Ni is 22 to 34%, and the balance is substantially Co and unavoidable impurities, but Co is 37 to 48%. desirable.

A guide wire assists in inserting a diagnostic or therapeutic catheter used in a blood vessel to a predetermined position in the blood vessel, and has a structure in which a thin wire is wrapped around a core wire. The guide wire is required to have sufficient strength and ductility so that the rotation of the tip follows the rotation of the hand, torque transmission, and to prevent breakage during treatment. Non-Patent Document 2 describes a general relationship between strength and hardness.

JP 2019-147982 A

L605, which is a Co--Cr alloy and Ti--Ni alloy, which are currently used, are materials that are difficult to cold work, and their processing costs are very high compared to SUS316.
Recently, there is a demand for cobalt-chromium alloy members having high mechanical strength and ductility that are suitable for medical devices, gas turbine devices, and other industrial equipment devices.
In particular, there is a demand for the use of indwelling medical devices such as stents in blood vessels with fine and complicated shapes such as nerve defects and cerebral vessels. It is necessary to make it thin, and even so, a material with as high strength as possible is required in order to secure a sufficient blood vessel holding force. This also leads to a reduction in the amount of metal placed in the body.
Using a wire that is as thin as possible for the guide wire makes it easier to insert it into a fine blood vessel, but it needs to be as strong as possible in order to achieve even better torque transmissibility. Furthermore, a ductile material is desirable to prevent breakage during use.

An object of the present invention is to provide a cobalt-chromium alloy member suitable for use in medical devices, gas turbine devices, and other industrial equipment devices.
In particular, another object of the present invention is to provide a cobalt-chromium alloy member suitable for a guide wire that facilitates the insertion of an indwelling medical device such as a stent into a fine blood vessel.

In order to achieve the above objects, the cobalt-chromium alloy member of the present invention employs the following configuration.
[1] In mass%, Ni is 23 to 32%, Co is 37 to 48%, Mo is 8 to 12%, and the balance contains Cr and inevitable impurities,
20 ≤ [Cr%] + [Mo%] + [% of unavoidable impurities] ≤ 40,
It consists of a composition that satisfies
It has a crystal structure consisting of a face-centered cubic lattice (fcc), or a crystal structure consisting of a face-centered cubic lattice (fcc) and a hexagonal lattice (hcp), and has an average crystal grain size of 2 to 15 μm, Local crystal orientation variation (KAM value) is 0.0 or more and 1.0 or less,
A cobalt-chromium alloy member having a tensile strength of 800-1200 MPa and a breaking elongation of 30-80%.

[2] The cobalt-chromium alloy member according to [1] is preferably
It is preferable that the cobalt-chromium alloy material having the above composition is cold-plastic-worked into a predetermined shape, and the as-processed cobalt-chromium alloy material is heat-treated at a heat treatment temperature exceeding the recrystallization temperature of the cobalt-chromium alloy material.
[3] The cobalt-chromium alloy member according to [1] or [2] preferably contains 25 to 29% Ni, 37 to 48% Co, and 9 to 11% Mo in mass%, The remainder contains Cr and inevitable impurities,
23 ≤ [Cr%] + [Mo%] + [% of unavoidable impurities] ≤ 38,
It is preferable that the composition satisfies
[4] The cobalt-chromium alloy member according to [3] is
The as-processed cobalt-chromium alloy material obtained by cold plastic working the cobalt-chromium alloy material having the above composition into a predetermined shape is subjected to heat treatment at a heat treatment temperature exceeding the recrystallization temperature of the cobalt-chromium alloy material at a temperature of 800 ° C. or more and 1100 ° C. The heat treatment may be performed for 1 minute or more and 60 minutes or less as follows.

[5] In the cobalt-chromium alloy member according to any one of [1] to [4],
The inevitable impurities contain Ti, Mn, Fe, Nb, W, Al, Zr, B, and C in mass%, Ti is 1.0% or less, Mn is 1.0% or less, and Fe is 1 .0% or less, Nb is 1.0% or less, W is 1.0% or less, Al is 0.5% or less, Zr is 0.1% or less, B is 0.01% or less and C is 0.1% % or less.

[6] A cobalt-chromium alloy member having the composition according to any one of [1] to [5],
The predetermined shape that has been plastically worked in the cold is a tubular shape,
The average value of the crystal grain size is 2 to 15 μm, and the local crystal orientation change amount (KAM value) is 0.1 or more and 0.8 or less,
The cobalt-chromium alloy member preferably exhibits a tensile strength of 800 to 1000 MPa and a breaking elongation of 30 to 80%.
[7] A cobalt-chromium alloy member having the composition according to any one of [1] to [5],
The predetermined shape that has been plastically worked in the cold is a wire shape,
The average crystal grain size is 4 to 15 μm, and the local crystal orientation change amount (KAM value) is 0.0 or more and 1.0 or less,
The cobalt-chromium alloy member preferably exhibits a tensile strength of 1000 to 1200 MPa and a breaking elongation of 30 to 60%.

[8] A device using the cobalt-chromium alloy member according to any one of [1] to [7]. Preferably, the device is a medical device, gas turbine device, or other industrial device.

[9] The device according to [8] is preferably a medical device such as a stent, tube, wire, or implant.
[10] The device of [9] is for any of the combustor and exhaust components of aeronautical and industrial gas turbine engines, such as transition pieces, combustor cans, spray bars, frame holders, afterburners, tail pipes, etc. It is preferable that it is a device for a gas turbine.
[11] The device described in [9] is a device for industrial equipment used in waste incinerators, boilers, high-temperature reaction vessels and rotary calciners, as well as petrochemical production plants and synthesis gas plants. Good.

[12] 23 to 32% by mass of Ni, 37 to 48% of Co, and 8 to 12% of Mo, with the balance containing Cr and inevitable impurities,
20 ≤ [Cr%] + [Mo%] + [% of unavoidable impurities] ≤ 40,
Prepare a cobalt-chromium alloy material with a composition that satisfies
Homogenizing the prepared cobalt-chromium alloy material at 1100° C. to 1300° C.,
The homogenized cobalt-chromium alloy material is subjected to cold plastic working into a tubular or wire-like shape to obtain an as-processed cobalt-chromium alloy material,
The as-worked cobalt-chromium alloy material that has been plastically worked by cold is subjected to a heat treatment at a temperature exceeding the recrystallization temperature of the cobalt-chromium alloy material to 1100 ° C. or less for 1 minute or more and 60 minutes or less to obtain a face-centered cubic lattice ( fcc), or a crystal structure consisting of a face-centered cubic lattice (fcc) and a hexagonal lattice (hcp), the average grain size is 2 to 15 μm, and the local crystal orientation A method for producing a cobalt-chromium alloy member, characterized in that the amount of change (KAM value) is 0.0 or more and 1.0 or less.

The cobalt-chromium alloy member of the present invention has a crystal structure consisting of a face-centered cubic lattice (fcc) or a face-centered cubic lattice (fcc) and a hexagonal system by heat treatment above the recrystallization temperature after cold plastic working. Since it has a crystal structure consisting of a lattice (hcp), the average crystal grain size is 2 to 15 μm, and the local crystal orientation change amount (KAM value) is 0.0 or more and 1.0 or less, It has excellent mechanical properties such as improved strength and ductility, and is more reliable than existing products. For this reason, when a medical device to be placed in the body such as a stent is manufactured using the cobalt-chromium alloy member of the present invention, the reliability of the stent during mounting is enhanced, and the mounting of the stent on the affected area is facilitated.

In the cobalt-chromium alloy member of the present invention, an alloy mainly composed of Co, Ni, Cr, and Mo is subjected to cold plastic working, and then subjected to heat treatment at a recrystallization temperature or higher to obtain a face-centered cubic lattice (fcc). Phase stabilizes. As a result, in the formed fcc phase, transformation from fcc to hexagonal lattice (hcp) occurs due to fcc twinning deformation and deformation induction during deformation of the cobalt-chromium alloy member, resulting in high work hardenability and excellent mechanical properties. Shows strength and ductility.
When the cobalt-chromium alloy member of the present invention further contains solute atoms such as Mo and Nb, they can be segregated at stacking faults of dislocation cores or extended dislocations to make it difficult for cross slip to occur, and work hardening. further increases the mechanical strength.

FIG. 3 is a comparative diagram of low cycle fatigue life of cobalt-chromium alloy materials used in the present invention. As-processed cobalt-chromium alloy material (upper) produced by cold-working a cobalt-chromium alloy material according to an embodiment of the present invention into a tubular shape, and cobalt-chromium alloy member (lower) obtained by heat-treating this at 1050° C. for 5 minutes. 1 is a photograph of the overall appearance of the tube. As-processed cobalt-chromium alloy material (upper) produced by cold-working a cobalt-chromium alloy material according to an embodiment of the present invention into a tubular shape, and cobalt-chromium alloy member (lower) obtained by heat-treating this at 1050° C. for 5 minutes. 1 is an external appearance photograph (enlarged photograph) of a main part of a tube of . An as-processed material obtained by cold-working a cobalt-chromium alloy material according to an embodiment of the present invention into a tubular shape, and heat-treating this at temperatures of 650°C, 750°C, 850°C, 950°C, and 1050°C for 5 minutes. It is a stress-strain diagram obtained in a tensile test for a heat-treated material. Yield stress, tensile strength, and elongation at break of an as-processed material obtained by cold-working a cobalt-chromium alloy material according to an embodiment of the present invention into a tubular shape, and a heat-treated material obtained by further heat-treating this at each temperature. , and heat treatment temperature. Comparison of yield stress (σ _0.2 ), tensile strength (σ _UTS ), and total elongation at break for the tube (solid line) and the L605 alloy tube (dashed line) as the cobalt-chromium alloy member of the present invention It is a drawing. Obtained by EBSD for the as-processed material obtained by cold working the alloy material according to the present invention into a tubular shape, and the heat-treated material obtained by heat-treating this for 5 minutes at temperatures of 650 ° C., 750 ° C., 850 ° C., 950 ° C., and 1050 ° C. It is an IQ map. Obtained by EBSD for the as-processed material obtained by cold working the alloy material according to the present invention into a tubular shape, and the heat-treated material obtained by heat-treating this for 5 minutes at temperatures of 650 ° C., 750 ° C., 850 ° C., 950 ° C., and 1050 ° C. is a KAM map. Crystals calculated from the crystal orientation map for the as-processed material cold-worked into a tubular shape according to the present invention and the heat-treated material obtained by heat-treating this at temperatures of 650 ° C., 750 ° C., 850 ° C., 950 ° C., and 1050 ° C. for 5 minutes. It is drawing which shows a particle size. 1 is an overall appearance photograph of a wire as a cobalt-chromium alloy member according to the present invention. 4 is an external view photograph (enlarged photograph) of a main part of a wire as a cobalt-chromium alloy member according to the present invention. The stress obtained in the tensile test for the heat-treated material obtained by heat-treating the as-processed material obtained by cold-working the cobalt-chromium alloy material according to the present invention into a wire shape at temperatures of 650°C, 850°C, and 1050°C for 5 minutes- FIG. 4 is a strain diagram; 1 is a drawing showing the relationship between yield stress, tensile strength, elongation at break, and heat treatment temperature for a cobalt-chromium alloy member as a wire according to the present invention. It is an IQ map obtained by EBSD for the as-processed material cold-worked into a wire according to the present invention and the heat-treated material obtained by heat-treating this at temperatures of 450°C, 650°C, 850°C, and 1050°C for 5 minutes. It is a KAM map obtained by EBSD for the wire according to the present invention as-processed material and heat-treated material obtained by heat-treating this at temperatures of 450° C., 650° C., 850° C., and 1050° C. for 5 minutes. Calculated from the crystal orientation map measured by EBSD for the as-processed material cold-worked into a wire shape according to the present invention and the heat-treated material obtained by heat-treating this for 5 minutes at temperatures of 450 ° C., 650 ° C., 850 ° C., and 1050 ° C. There is a drawing showing the grain size.

[Overview of the present invention]
The cobalt-chromium alloy member of the present invention is a cobalt-chromium alloy obtained by cold plastic working (hereinafter also simply referred to as "cold working") a cobalt-chromium alloy material having a specific composition into a predetermined shape such as a tube or wire. By subjecting the as-processed material to a specific heat treatment above the recrystallization temperature, a crystal structure consisting of a face-centered cubic lattice (fcc), or from a face-centered cubic lattice (fcc) and a hexagonal lattice (hcp) The average crystal grain size is 2 to 15 μm, the local crystal orientation change amount (KAM value) is 0.0 or more and 1.0 or less, and the tensile strength is 800 to A member is obtained which exhibits a tensile strength of 1200 MPa and an elongation at break of 30-80%. In particular, the cobalt-chromium alloy member of the present invention is characterized in that a member having a local crystal orientation variation (KAM value) of 0.0 or more and 1.0 or less can be obtained. As a result, a cobalt-chromium alloy member exhibiting high work hardening ability and excellent mechanical strength and ductility can be obtained.
The details of the present invention will be described below.

[Details of the present invention]
(cobalt-chromium alloy material)
The cobalt-chromium alloy material of the present invention contains 23 to 32% Ni, 37 to 48% Co, and 8 to 12% Mo, and the balance contains Cr and inevitable impurities, and 20≦[Cr%]+ The composition satisfies [Mo %] + [% of unavoidable impurities] ≤ 40.
The unavoidable impurity is not an intentionally added ingredient, but an ingredient that is unavoidably mixed due to the material or process. The components of the unavoidable impurities are not particularly limited, but are, for example, Ti, Mn, Fe, Nb, W, Al, Zr, B, C, etc., and may not be included.
In addition, the cobalt-chromium alloy material of the present invention is not particularly limited as long as it has a specific composition range. It may be hot-worked or machined into a specific shape by cutting or the like.

The reason for limiting the composition range of the cobalt-chromium alloy material of the present invention will be explained below.
The content of each component in the cobalt-chromium alloy material is the content (% by mass, hereinafter simply referred to as "%") when the entire cobalt-chromium alloy material is taken as 100% by mass.
Also, the numerical range of the present invention includes upper and lower limits. The same applies not only to the composition range shown below, but also to the range of temperature treatment, the range of tensile strength, the range of elongation at break and the range of uniform elongation. However, this does not apply when it is specified that the numerical range does not include the upper limit or lower limit, such as "more than" or "less than".

Ni (nickel) stabilizes the face-centered cubic lattice phase, maintains workability, improves corrosion resistance, improves low-cycle fatigue life, and increases strength and ductility by heat treatment above the recrystallization temperature after cold working. It has the effect of improving However, in the composition range of Co, Cr, and Mo of the cobalt-chromium alloy material of the present invention, if the Ni content is less than 23%, it is difficult to obtain the effect of improving strength and ductility by the heat treatment, and 32% is not. Since it is difficult to obtain the effect of improving strength and ductility by the heat treatment even if it exceeds, the Ni content of the present invention is 23 to 32%, preferably 25 to 29%. Thereby, the effect of improving strength and ductility is further obtained.

Co (cobalt) itself has a large work hardening ability, reduces notch brittleness, increases fatigue strength, increases high temperature strength, improves low cycle fatigue life, and exceeds the recrystallization temperature after cold working. This heat treatment has the effect of improving strength and ductility.
If the Co content is less than 37%, the effect is weak, and if it exceeds 48% in the present composition, the matrix becomes too hard and processing becomes difficult, and the heat treatment above the recrystallization temperature after cold working increases the strength and strength. The effect of improving ductility is lost. Therefore, the Co content of the present invention is 37-48%, preferably 40-45%. Thereby, the effect of improving strength and ductility is further obtained.

Mo (molybdenum) has the effect of solid-solving into the matrix to strengthen it, the effect of increasing work hardening ability, and the effect of increasing corrosion resistance when coexisting with Cr. However, if the Mo content is less than 8%, the desired effect cannot be obtained, and if it exceeds 12%, the workability drops sharply and a brittle σ phase tends to form. Therefore, the content of Mo in the present invention is 8-12%, preferably 9-11%. Thereby, the effect of improving strength and ductility is further obtained.

When the total content of Cr, Mo, and inevitable impurities is less than 20%, the hexagonal lattice (hcp) phase becomes stable when the total content of the cobalt-chromium alloy material is 100%, and when it exceeds 40%, the face-centered cubic lattice The (fcc) phase becomes unstable and a body-centered cubic (bcc) layer tends to appear. That is, when the total content of Cr, Mo, and unavoidable impurities is not 20 to 40%, the fcc phase is difficult to stabilize. Transformation from fcc to hcp is difficult to occur, and low cycle fatigue life along with excellent ductility cannot be obtained. Accordingly, the total content of Cr, Mo and unavoidable impurities in the present invention is 20-40%, preferably 23-38%. This provides low cycle fatigue life along with excellent ductility.
The content of the inevitable impurities may be 0%, and when it exceeds 0%, the composition of the inevitable impurities is such that the total is 100% based on the composition ratio of Co, Ni, Cr, and Mo. Proportions are adjusted.

　Cr (chromium) is an essential component for ensuring corrosion resistance, and also has the effect of strengthening the matrix. When the amount of unavoidable impurities is 0%, the Cr content in the present invention is preferably 12-28%, more preferably 14-27%, still more preferably 18-22%. When it is 12% or more, excellent corrosion resistance is likely to be obtained, and when it is 28% or less, it is difficult for the workability and toughness to rapidly decrease. This provides better corrosion resistance while ensuring workability and toughness.

Ti (titanium) has strong deoxidizing, denitrifying, and desulfurizing effects, but if it is too large, inclusions increase in the alloy and η phase (Ni ₃ Ti) precipitates, reducing toughness. The content of Ti in the invention is desirably 1.0% or less as an unavoidable impurity.

Mn (manganese) has the effect of deoxidizing and desulfurizing, and the effect of stabilizing the face-centered cubic lattice phase. 0.5% or less is desirable. More desirably, the upper limit as an unavoidable impurity is 1.0% or less.

Fe (iron) has the function of stabilizing the face-centered cubic lattice phase and improving workability. % or less.

C (carbon) forms a solid solution in the matrix and also forms carbides with Cr, Mo, etc., and has the effect of preventing coarsening of crystal grains. The content of C in the invention is desirably 0.1% or less.

Nb (niobium) dissolves in the matrix and strengthens it, and has _the effect of increasing the work hardening ability. Therefore, the content of Nb in the present invention is desirably 3.0% or less. More desirably, the upper limit as an unavoidable impurity is 1.0% or less.

W (tungsten) dissolves in the matrix and strengthens it, and has the effect of significantly increasing the work hardening ability. The content of W in the invention is desirably 5.0% or less. More desirably, the upper limit as an unavoidable impurity is 1.0% or less.

Al (aluminum) has the effect of deoxidizing and improving oxidation resistance, but if it is too much, deterioration of corrosion resistance etc. will occur, so the content of Al in the present invention is 0.5% or less. desirable.

Zr (zirconium) has the effect of increasing the grain boundary strength at high temperatures and improving hot workability. It is desirable to be 0.1% or less.

B (boron) has the effect of improving hot workability, but if it is too much, the hot workability decreases and cracks easily. It is desirable to have

(as-processed cobalt-chromium alloy material)
The as-worked cobalt-chromium alloy material of the present invention is obtained by cold-working the cobalt-chromium alloy material into a predetermined shape.
In the present invention, fcc deformation twins and hcp phase (ε phase) are introduced by twinning deformation and induced transformation during cold working, and a belt-like deformation band structure with high density is formed. This gives very high strength. In addition, in the present invention, crystal grains are refined by cold working, and higher strength can be easily obtained.

Although the predetermined shape is not particularly limited, it is preferably tubular or wire-like, for example. This allows for use in tube or wire shaped medical or aerospace devices.

(Cobalt-chromium alloy member)
The cobalt-chromium alloy member of the present invention is obtained by subjecting the as-processed cobalt-chromium alloy material to a specific heat treatment above the crystallization temperature.
The cobalt-chromium alloy member of the present invention has the same composition as the cobalt-chromium alloy material, and contains 23 to 32% Ni, 37 to 48% Co, and 8 to 12% Mo in mass%, The remainder contains Cr and inevitable impurities, and has a composition that satisfies 20 ≤ [Cr%] + [Mo%] + [% of inevitable impurities] ≤ 40. Preferably, Ni is 25 to 29% in mass%, A composition containing 37 to 48% Co and 9 to 11% Mo, the balance containing Cr and inevitable impurities, and satisfying 23 ≤ [Cr%] + [Mo%] + [% of inevitable impurities] ≤ 38 It should consist of

The unavoidable impurities include Ti, Mn, Fe, Nb, W, Al, Zr, B, and C in mass %, Ti being 1.0% or less, Mn being 1.0% or less, and Fe being 1.0%. 0% or less, Nb 1.0% or less, W 1.0% or less, Al 0.5% or less, Zr 0.1% or less, B 0.01% or less and C 0.1% It should be below.
As a result, high work hardening ability and excellent mechanical strength and ductility can be easily obtained.

The cobalt-chromium alloy member of the present invention has a crystal structure consisting of a face-centered cubic lattice (fcc) or a crystal structure consisting of a face-centered cubic lattice (fcc) and a hexagonal lattice (hcp).
That is, in the present invention, fcc deformation twins or hcp phases in the as-worked cobalt-chromium alloy material are transformed into fcc phases by heat treatment. Due to the formation of the fcc phase, when the cobalt-chromium alloy member is deformed, fcc-twin deformation or deformation-induced transformation from fcc to hcp occurs again. The cobalt-chromium alloy member of the present invention, in which such deformation and transformation occur, is excellent in mechanical strength and ductility.

The cobalt-chromium alloy member of the present invention has a local crystal orientation change amount (KAM value) of 0.0 or more and 1.0 or less.
The KAM value is, for example, a local change in crystal orientation obtained by back electron scattering diffraction (EBSD) measurement, and can be represented by the local misorientation (Kernel Average Misorientation: KAM) defined by the following formula (1). can.

(1)
where α _i,j denotes the crystal misorientation between measurement points i and j. A specific calculation procedure is described, for example, in Koei Sasaki et al., "Relationship between microscopic plastic strain distribution and crystal misorientation", Journal of the Japan Institute of Metals, Vol. 74, pp. 467-474 (2010). . The KAM value takes a high value in a region with a high density of lattice defects such as dislocations or in a region where the curvature of the crystal lattice plane is remarkable.
The KAM value can be used to evaluate the strain distribution within the crystal grains. In the present invention, the KAM value is as low as 0.0 or more and 1.0 or less, and the density of lattice defects such as dislocations is low, so that the cobalt-chromium alloy member of the present invention is excellent in mechanical strength. In addition, since the crystal grains are easily homogenized, excellent crystallinity and homogenized mechanical properties are easily obtained.

The average grain size of the cobalt-chromium alloy member of the present invention is 2 μm or more and 15 μm or less, preferably 4 μm or more and 15 μm or less, and more preferably 4 μm or more and 10 μm or less. Thereby, high mechanical strength is likely to be secured.
The average grain size is calculated by an area fraction method based on EBSD. Specifically, the average grain size is determined according to JIS G0551 "Steel-Microscopic Test Method for Grain Size" and ASTM E112-13 "Standard Test Methods for Determining Average Grain Size (Standard Test Method for Determining Average Grain Size). can be calculated according to

The cobalt-chromium alloy member of the present invention has a tensile strength of 800-1200 MPa.
The cobalt-chromium alloy member has an elongation at break of 30 to 80%, preferably 30 to 60%, more preferably 50 to 60%.
Tensile strength and elongation at break are measured, for example, by a tensile test using an autograph manufactured by Shimadzu Corporation.
A cobalt-chromium alloy member having the above physical properties is excellent in mechanical strength and ductility.

Cobalt-chromium alloy members preferably have a uniform elongation of 25 to 60%, more preferably 30 to 60%, even more preferably 50 to 60%.
Uniform elongation is measured, for example, by a tensile test using an autograph manufactured by Shimadzu Corporation.
A cobalt-chromium alloy member having the above physical properties is superior in mechanical strength and ductility.

In particular, when the cobalt-chromium alloy member of the present invention has a tubular shape with a hollow interior and a peripheral surface surrounded by a cobalt-chromium alloy, the average grain size is 2 to 15 μm, and the local crystal orientation is It is preferred that the amount of change (KAM value) is 0.1 or more and 0.8 or less, the tensile strength is 800 to 1000 MPa, and the elongation at break is 30 to 80%.
When the cobalt-chromium alloy member of the present invention has a wire-like cross-sectional shape such as a circular cross-section, an elliptical cross-section, a flat cross-section, a concave or convex irregular cross-section, etc., the average grain size is 4 to 15 μm. It is preferable that the local crystal orientation change (KAM value) is 0.0 or more and 1.0 or less, the tensile strength is 1000 to 1200 MPa, and the breaking elongation is 30 to 60%.
This results in higher strength and better ductility.

The cobalt-chromium alloy member of the present invention is preferably obtained by heat treatment under the following conditions.
The temperature of the heat treatment of the present invention is preferably higher than the recrystallization temperature of the cobalt-chromium alloy material and 1100°C or less, more preferably 800°C or more and 1100°C or less, and still more preferably 900°C or more and 1100°C or less. . The recrystallization temperature of the cobalt-chromium alloy material is, for example, in the range of 780° C. to 820° C. for the Co-20Cr-10Mo-26Ni alloy, which is the composition of the present embodiment, but may range from 750° C. to 820° C. depending on the alloy composition of the cobalt-chromium alloy material. It may be in the range of 1000°C.
By setting the temperature above the recrystallization temperature, recrystallization occurs and the fcc phase is stabilized. By setting the temperature to 1100° C. or less, coarsening of the crystal grain size is suppressed.
As a result, a cobalt alloy member having tensile strength, uniform elongation and elongation at break within the above ranges and having high mechanical strength and ductility can be obtained.

The heat treatment time of the present invention is preferably 1 minute or more and 60 minutes or less. By setting the time to 1 minute or longer, the recrystallization is sufficiently performed, and the fcc phase is stabilized. Coarsening of the crystal grain size can be suppressed by setting the heating time to 60 minutes or less.
Thereby, it is easy to obtain a cobalt alloy member having tensile strength, uniform elongation and breaking elongation within the above ranges and having high mechanical strength and ductility.

In particular, the cobalt-chromium alloy member is heat-treated at a heat treatment temperature exceeding the recrystallization temperature of the cobalt-chromium alloy material for 1 minute or more and 60 minutes or less for 1 minute or more and 60 minutes or less. It is preferably obtained by heat treatment.

The cobalt-chromium alloy member of the present invention may have a belt-shaped deformation band structure. The band-shaped deformation band structure of the present invention is an aggregate structure of dislocation cells in which a large number of dislocations generated by cold working are densely packed. It is a nearby tissue.

The cobalt-chromium alloy member of the present invention has a low stacking fault energy, and high work hardening ability is obtained by the movement of partial dislocations during deformation and the formation of fine plate-like fcc twins and hcp phases. In addition, compared to Co, Ni, and Cr, whose atomic radius is 1.25 Å, solute atoms such as Mo and Nb, which have atomic radii larger or similar, are resistant to stacking faults of dislocation cores or extended dislocations. It is attracted and segregates, making it difficult for cross-slip to occur, resulting in high work hardening ability.

In addition, since the high work hardening ability of the cobalt-chromium alloy member of the present invention is exhibited not only at around body temperature but also at high temperatures, it is characterized by high high-temperature strength characteristics. Therefore, the application of the cobalt-chromium alloy member is not limited to medical use, and the cobalt-chromium alloy member of the present invention is suitable for use under more severe conditions for industrial equipment such as aerospace and steam turbines. It is tolerable.

(Manufacturing method of cobalt-chromium alloy member)
A method for manufacturing a cobalt-chromium alloy member includes the steps of preparing a cobalt-chromium alloy material, homogenizing the prepared cobalt-chromium alloy material at 1100° C. to 1300° C., and dispersing the homogenized cobalt-chromium alloy material. a step of subjecting a tube-shaped or wire-shaped shape to cold plastic working to obtain an as-worked cobalt-chromium alloy material; It includes a step of performing a heat treatment at a temperature above the recrystallization temperature of 1100° C. or less for 1 minute or more and 60 minutes or less. The recrystallization temperature of the cobalt-chromium alloy material is, for example, 800.degree.
Thereby, a cobalt-chromium alloy member having high mechanical strength and ductility can be obtained.

The above cobalt alloy material is used in the step of preparing the cobalt chromium alloy material.
In the step of cold plastic working, the cobalt-chromium alloy cold-worked material can be obtained in the form of a tube or a wire.
In the step of heat-treating the unprocessed cobalt-chromium alloy material, the cobalt-chromium alloy member is obtained.

In the homogenization treatment, the cobalt-chromium alloy material is heat-treated at 1100° C. to 1300° C. to uniformly disperse each composition. This ensures the uniformity of the mechanical properties in the subsequent cold working process.
By setting the homogenization treatment temperature to 1100 ° C. or higher, it is possible to efficiently homogenize the material, and by setting it to 1300 ° C. or lower, it is possible to prevent the crystal grains from becoming excessively coarse, and the material surface can prevent significant oxidation of Other conditions for the homogenization treatment can be appropriately set within a range that does not impair the physical properties of the cobalt-chromium alloy member to be obtained.
The cobalt-chromium alloy material to be homogenized may be any cobalt-chromium alloy material having the specific composition described above, and may be, for example, an alloy ingot produced by high-frequency melting.
Further, the cobalt-chromium alloy material after the homogenization treatment may be hot-worked into a shape that is easily cold-worked, such as a round bar.

Further, in the method for producing a cobalt-chromium alloy member of the present invention, the as-processed cobalt-chromium alloy material obtained by cold-working the cobalt-chromium alloy material into a plate material for a stent is subjected to heat treatment at a recrystallization temperature or higher and 1100° C. or lower, and then subjected to 200°C. The aging treatment may be performed at a temperature of 0° C. or more and the recrystallization temperature or less. As a result, solute atoms such as Mo are attracted to stacking faults of dislocation cores or extended dislocations to fix the dislocations, so-called static strain aging, whereby higher strength characteristics can be obtained.

For the cobalt-chromium alloy material of the present invention, an alloy ingot having the same composition as the cobalt-chromium alloy material is produced by high-frequency melting, hot forged at 1100° C. to 1300° C., homogenized, and hot rolled. It is obtained by cutting a round bar with a diameter of 8 mm and a length of 270 mm.

According to the above production method of the present invention, a crystal structure consisting of a face-centered cubic lattice (fcc), or a crystal structure consisting of a face-centered cubic lattice (fcc) and a hexagonal lattice (hcp), and having an average crystal grain size is 2 to 15 μm, and the amount of local crystal orientation change (KAM value) is 0.0 or more and 1.0 or less.

A first embodiment of the present invention uses the cobalt-chromium alloy material of the present invention to form a tubular member.
That is, a tube material having a diameter of 1.6 mm, a thickness of 0.1 mm, and a length of 1 m was obtained by cold working the cobalt-chromium alloy material. This tube material corresponds to the cobalt-chromium alloy as-processed material. Further, the tube material was subjected to a predetermined heat treatment to impart ductility to obtain a cobalt-chromium alloy member as a tube material.

Table 1 shows the composition of the cobalt-chromium alloy material used in this example. The unit is % by mass.

In Examples 1 to 4, the Cr content was constant at 20% by mass and the Mo content was 10% by mass, and the Co content was varied with respect to the Ni content. The Ni content was varied in the range of 23 to 32% by mass.
In Comparative Examples 1 to 4, as comparative materials, commercially available Co-20Cr-10Mo-35Ni alloy (hereinafter simply referred to as "MP35N alloy"), Co-20Cr-10Mo-20Ni alloy, Co-20Cr-15W -10Ni alloy (hereinafter simply referred to as "L605 alloy") and SUS316L (manufactured by Hayes) were used. Examples 1 to 4 were confirmed to have a crystal structure consisting of a face-centered cubic lattice (fcc) or a crystal structure consisting of a face-centered cubic lattice (fcc) and a hexagonal lattice (hcp).

A low cycle fatigue test at a strain amplitude of 0.01 was performed on the cobalt-chromium alloy materials having the compositions of Examples 1 to 4 and the alloys having the compositions of Comparative Examples 1 to 4, which were hot-worked into bars and then heat-treated at 1200°C for 1 minute. did

The test results are shown in Fig. 1. All of Examples 1 to 4 had a good fatigue life of 3000 cycles or more. In particular, the cobalt-chromium alloy materials of 23% by mass Ni (Example 4), 26% by mass Ni (Example 3), and 29% by mass Ni (Example 2) were used in any of Comparative Examples 1 to 4. Improvement in low cycle fatigue life was observed compared to the product.

In addition, the cobalt-chromium alloy materials of Examples 1 to 4 and the alloys of Comparative Examples 1 to 4, which were hot-worked into bars and then heat-treated at 1200 ° C. for 1 minute, were subjected to Tensilon tensile tests manufactured by Y&D. A tensile test was performed using a machine at a strain rate of 2.5×10 ⁻⁴ s ⁻¹ , and the results are shown in Table 2. The cobalt-chromium alloy materials according to Examples 1 to 4 exhibited tensile strengths of 848 to 886 MPa, exhibiting high tensile strength unique to cobalt-chromium alloys, which is equivalent to MP35N alloy (Comparative Example 1).

FIG. 2 shows a cobalt-chromium alloy as-processed material (upper), 1050, produced by cold-working the Co-20Cr-10Mo-26Ni alloy material according to Example 3, which has the best fatigue life among cobalt-chromium alloy materials. 2A is an overall photograph, and FIG. 2B is an enlarged photograph of a main part, showing the external appearance of a tube as a cobalt-chromium alloy member (lower) heat-treated at ℃ for 5 minutes. It has an outer diameter of 1.6 mm, a thickness of 0.1 mm, and a length of 980 to 1280 mm, and has good surface properties.

FIG. 3 shows the produced Co-20Cr-10Mo-26Ni alloy tube material, which is a cobalt-chromium alloy as-processed material after cold working (hereinafter also simply referred to as "as-processed material") and as-processed material. A drawing showing the tensile strength measurement results of cobalt-chromium alloy members (hereinafter also simply referred to as “heat-treated materials”) tubes that have been heat-treated at 650°C, 750°C, 850°C, 950°C, and 1050°C for 5 minutes. , the horizontal axis indicates strain [%] and the vertical axis indicates stress [MPa]. The tensile test was performed using an autograph manufactured by Shimadzu Corporation at a test speed of 1.2 mm/s and a gauge length of 110 mm.

Table 3 also shows the 0.2% proof stress [MPa], tensile strength [MPa], and elongation at break [%] obtained from FIG. Those heat-treated at 650° C. and 750° C. (also referred to simply as “650° C. and 750° C. heat-treated materials”, etc.) exhibited higher tensile strength and lower ductility than as-processed materials. Heat treatment at a temperature of 850°C or higher reduces the tensile strength, but increases the ductility. there were.

Fig. 4 shows the relationship between yield stress (YS), tensile strength (UTS), breaking elongation (Total elongation) and annealing temperature for the Co-20Cr-10Mo-26Ni alloy tube material. . The yield stress was shown as 0.2% proof stress (σ _0.2 ). When the heat treatment temperature is 850° C. or higher, the yield stress and tensile strength decrease, and the elongation at break remarkably increases.
Figure 5 shows the yield stress (σ _{0.0. 2} ), tensile strength (σ _UTS ), and elongation at break (Total elongation) in comparison with literature values (see Non-Patent Document 2) of L605 alloy. Yield stress and tensile strength [MPa] are plotted on the vertical axis, and elongation strain at break [%] is plotted on the horizontal axis. A solid line indicates the tube as the cobalt-chromium alloy member according to the present embodiment, and a dotted line indicates the L605 alloy tube. When compared to literature values for tensile strength, the yield stress of the tube of the present invention is higher than that of the L605 alloy tube which exhibits comparable elongation. In addition, it exhibits a greater elongation than L605, which exhibits a comparable yield stress. Also, the material heat-treated at a temperature of 850° C. or higher for 5 minutes has a strength comparable to that of the L605 material, but exhibits a greater elongation at break.

Fig. 6 shows an as-processed material obtained by cold working a Co-20Cr-10Mo-26Ni alloy material into a tubular shape, and a heat-treated material obtained by heat-treating this at temperatures of 650°C, 750°C, 850°C, 950°C, and 1050°C for 5 minutes. IQ map obtained by electron back scattering diffraction (EBSD) method for . The IQ map, also called an image quality map, is a map that indicates whether the crystallinity is good or bad. It is a plot of the intensity of peaks showing bands in the Hough space when the EBSD pattern is Hough transformed (a method of converting a straight line into a point). take a value.
What appears linear in FIG. 6 is a region of poor crystallinity such as grain boundaries, dislocations, and stacking faults. The as-worked material and the material heat-treated at 650° C. and 750° C. have a high dislocation density and a worked structure remains, but the heat-treated material heat-treated at a temperature of 850° C. or higher has a recrystallized structure. Also, as the heat treatment temperature increases, the crystal grain size increases.

FIG. 7 shows the as-processed material obtained by cold working a Co-20Cr-10Mo-26Ni alloy material into a tubular shape, and the heat-treated material obtained by heat-treating this at temperatures of 650° C., 750° C., 850° C., 950° C., and 1050° C. for 5 minutes. is a KAM map showing the KAM values obtained by EBSD of . The KAM value is calculated by the above formula (1), and the numerical values in the figure are the average KAM values within the field of view.
The as-processed material and the material heat-treated at 650°C and 750°C have a high dislocation density, and the processed structure remains, so the average KAM value is as high as 1 or more. It is a recrystallized structure with a low defect density as low as below. Also, as the heat treatment temperature increases, the crystal grain size increases.
That is, the KAM value of the as-processed material is 1.32 ± 0.74, whereas the KAM value of the 650 ° C heat-treated material, which is lower than the recrystallization temperature, is 1.26 ± 0.71, and the 750 ° C heat-treated material is 1.25±0.69. On the other hand, it is 0.48±0.30 for the material heat-treated at 850°C, which is higher than the recrystallization temperature, 0.47±0.30 for the material heat-treated at 950°C, and 0.32±0.15 for the material heat-treated at 1050°C. is.

Fig. 8 shows as-processed material obtained by cold working a Co-20Cr-10Mo-26Ni alloy material into a tubular shape, and heat-treated material obtained by heat-treating this at temperatures of 650 ° C, 750 ° C, 850 ° C, 950 ° C and 1050 ° C for 5 minutes. showed a grain size of The crystal grain size was calculated from a crystal orientation map (a map showing the distribution of specified crystal orientations) measured by EBSD.
The average crystal grain size of the as-processed material is 5.1 μm, while that of the material heat-treated at 650° C., which is lower than the recrystallization temperature, is 5.3 μm, and that of the material heat-treated at 750° C. is 4.3 μm. On the other hand, the material heat-treated at 850° C., which is higher than the recrystallization temperature, has a thickness of 2.3 μm, the material heat-treated at 950° C. has a thickness of 3.2 μm, and the material heat-treated at 1050° C. has a thickness of 7.6 μm. In the heat treatment at 850° C., fine crystal grains of 2.3 μm are obtained by recrystallization.

A second embodiment of the present invention uses the cobalt-chromium alloy material of the third embodiment of the present invention to form a wire-shaped member. That is, a wire material having a diameter of 0.5 mm and a length of 1 m was obtained by cold working a cobalt-chromium alloy material. This wire material corresponds to the unprocessed cobalt-chromium alloy material. Further, the wire material was subjected to a predetermined heat treatment to impart ductility to obtain a cobalt-chromium alloy member as a wire material.
FIG. 9 is a photograph of the appearance of a wire-shaped cobalt-chromium processed raw material produced by cold working, FIG. 9A being an overall photograph, and FIG. 9B being an enlarged photograph of a main part. It has a diameter of 0.5 mm and a length of 1000 mm, and has a good appearance.

FIG. 10 shows a heat-treated material obtained by heat-treating the Co-20Cr-10Mo-26Ni alloy material as-processed, which is obtained by cold-working the Co-20Cr-10Mo-26Ni alloy material into a wire shape, at 650° C., 850° C., and 1050° C. for 5 minutes. In the drawing showing the tensile strength measurement results, the horizontal axis shows the strain [%] and the vertical axis shows the stress [MPa]. The tensile test was performed using an autograph manufactured by Shimadzu Corporation at a test speed of 1.2 mm/s and a gauge length of 110 mm. No. 1 produced under the same conditions. 1 and 2 gave similar results.

Table 4 shows the as-worked cobalt-chromium alloy material cold-worked into the wire shape of the present invention, and the cobalt obtained by heat-treating the as-worked wire-shaped material at 450°C, 650°C, 850°C, and 1050°C for 5 minutes. The tensile strength [MPa] and elongation at break [%] of the wire as the chromium alloy member and the comparative wire are shown.

Table 5 compares the tensile strength and elongation at break of a wire as a cobalt-chromium alloy member according to an example of the present invention with SUS316L, L605 alloy, and MP35N alloy. The cobalt-chromium alloy members produced in Table 5 were produced under the same conditions as the cobalt-chromium alloy members produced in Table 4, and similar results were obtained.

Comparative example SUS316L: tensile strength 480 MPa, elongation at break 40%,
The numerical values (%) of "Comparative Example L605" and "Comparative Example MP35N" in Table 5 indicate the cold working rate.

A wire as a cobalt-chromium alloy member according to an embodiment of the present invention exhibits a strength exceeding that of SUS316L, which is most widely used as a guide wire, and exhibits tensile strength and elongation at break comparable to those of L605 alloy and MP35N wires. (Fig. 10, Table 5).

Fig. 11 shows the relationship between yield stress, tensile strength, elongation at break and heat treatment temperature for the Co-20Cr-10Mo-26Ni alloy wire. When the heat treatment temperature is 850° C. or higher, the yield stress and tensile strength decrease, and the elongation at break remarkably increases.

FIG. 12 shows the as-processed material obtained by cold working the Co-20Cr-10Mo-26Ni alloy material into a wire shape, and the heat-treated material obtained by heat-treating this at temperatures of 450 ° C., 650 ° C., 850 ° C. and 1050 ° C. for 5 minutes. IQ map obtained by EBSD. The as-processed material and the material heat-treated at 450° C. and 650° C. have a high dislocation density and retain a worked structure. Also, as the heat treatment temperature increases, the crystal grain size increases.

FIG. 13 shows the as-processed material obtained by cold-working the Co-20Cr-10Mo-26Ni alloy material into a wire shape, and the heat-treated material obtained by heat-treating this at temperatures of 450 ° C., 650 ° C., 850 ° C., and 1050 ° C. for 5 minutes. KAM map obtained by EBSD.
That is, the KAM value of the as-processed material is 1.76 ± 0.93, whereas the KAM value of the material heat-treated at 450 ° C., which is lower than the recrystallization temperature, is 2.34 ± 1.07, and the value of the material heat-treated at 650 ° C. is 2.04±1.05. On the other hand, it is 0.33±0.43 for the 850° C. heat treated material, which is higher than the recrystallization temperature, and 0.96±0.61 for the 1050° C. heat treated material.
The as-worked material and the 450°C and 650°C heat-treated materials have a high KAM value of 1.76 to 2.01, high dislocation density, and a worked structure remaining, but the temperature is 850°C, which is higher than the recrystallization temperature. The samples heat-treated at the above temperatures have a KAM value of 1 or less, and the density of defects such as dislocations is reduced.

FIG. 14 shows the as-processed material obtained by cold working a Co-20Cr-10Mo-26Ni alloy material into a tubular shape and the heat-treated material obtained by heat-treating this at temperatures of 450 ° C, 650 ° C, 850 ° C and 1050 ° C for 5 minutes with EBSD. The grain size calculated from the measured crystal orientation map is shown.
That is, the average crystal grain size of the as-processed material is 9.04 μm, while that of the material heat-treated at 450° C., which is lower than the recrystallization temperature, is 10.3 μm, and that of the material heat-treated at 650° C. is 7.78 μm. . On the other hand, the material heat-treated at 850° C., which is higher than the recrystallization temperature, is 4.43 μm, and the material heat-treated at 1050° C. is 12.1 μm. In the heat treatment at 850° C., which is a temperature higher than the recrystallization temperature, fine crystal grains of 4.4 μm are obtained by recrystallization.

As described in detail above, the cobalt-chromium alloy material having the alloy composition of the present invention is cold-worked into a predetermined shape such as a tube or wire, and then subjected to heat treatment above the recrystallization temperature of the cobalt alloy material. By doing so, a cobalt-chromium alloy member having high strength and high ductility can be obtained. Such a cobalt-chromium alloy member is suitable for use in medical devices, gas turbine devices, or other industrial equipment devices because it uses a cobalt-chromium alloy member with a long fatigue life.

Medical devices include indwelling medical devices such as stents, catheters, fastening cables, guide rods, orthopedic cables, heart valves, and implants. Other medical devices include bone drill bits and gallstone removal wires.
Gas turbine devices include combustor and exhaust components of aeronautical and industrial gas turbine engines such as transition pieces, combustor cans, spray bars, frame holders, afterburners, tail pipes, and the like. Industrial equipment devices are used in waste incinerators, boilers, high temperature reactors and rotary calciners, as well as petrochemical production plants and synthesis gas plants.

Claims (12)

1. In mass %, Ni is 23 to 32%, Co is 37 to 48%, Mo is 8 to 12%, and the balance contains Cr and inevitable impurities,
   20 ≤ [Cr%] + [Mo%] + [% of unavoidable impurities] ≤ 40,
   It consists of a composition that satisfies
   It has a crystal structure consisting of a face-centered cubic lattice (fcc), or a crystal structure consisting of a face-centered cubic lattice (fcc) and a hexagonal lattice (hcp), and has an average crystal grain size of 2 to 15 μm, Local crystal orientation variation (KAM value) is 0.0 or more and 1.0 or less,
   A cobalt-chromium alloy member having a tensile strength of 800-1200 MPa and a breaking elongation of 30-80%.
2. 1. Obtained by heat-treating an as-processed cobalt-chromium alloy material obtained by cold plastic working a cobalt-chromium alloy material having the above composition into a predetermined shape at a heat treatment temperature exceeding the recrystallization temperature of the cobalt-chromium alloy material. Cobalt-chromium alloy member according to.
3. In mass %, Ni is 25 to 29%, Co is 37 to 48%, Mo is 9 to 11%, and the balance contains Cr and inevitable impurities,
   23 ≤ [Cr%] + [Mo%] + [% of unavoidable impurities] ≤ 38,
   3. The cobalt-chromium alloy member according to claim 1, wherein the composition satisfies the following:
4. The as-processed cobalt-chromium alloy material obtained by cold plastic working the cobalt-chromium alloy material having the above composition into a predetermined shape is subjected to heat treatment at a heat treatment temperature exceeding the recrystallization temperature of the cobalt-chromium alloy material at a temperature of 800 ° C. or more and 1100 ° C. The cobalt-chromium alloy member according to claim 3, which is obtained by heat-treating for 1 minute or more and 60 minutes or less.
5. The inevitable impurities contain Ti, Mn, Fe, Nb, W, Al, Zr, B, and C in mass%, Ti is 1.0% or less, Mn is 1.0% or less, and Fe is 1 .0% or less, Nb is 1.0% or less, W is 1.0% or less, Al is 0.5% or less, Zr is 0.1% or less, B is 0.01% or less and C is 0.1% % or less, the cobalt-chromium alloy member according to any one of claims 1 to 4.
6. The predetermined shape that has been plastically worked in the cold is a tubular shape,
   The average value of the crystal grain size is 2 to 15 μm, and the local crystal orientation change amount (KAM value) is 0.1 or more and 0.8 or less,
   The cobalt-chromium alloy member according to any one of claims 1 to 5, having a tensile strength of 1000 to 1200 MPa and an elongation at break of 30 to 80%.
7. The predetermined shape that has been plastically worked in the cold is a wire shape,
   The average crystal grain size is 4 to 15 μm, and the local crystal orientation change amount (KAM value) is 0.0 or more and 1.0 or less,
   The cobalt-chromium alloy member according to any one of claims 1 to 5, having a tensile strength of 1000 to 1200 MPa and a breaking elongation of 30 to 60%.
8. A device using the cobalt-chromium alloy member according to any one of claims 1 to 7.
9. 9. The device of claim 8, wherein the device is a medical device such as a stent, tube, wire or implant.
10. 8. The device is a gas turbine device of any of the combustor and exhaust components of aeronautical and industrial gas turbine engines, such as transition pieces, combustor cans, spray bars, flame holders, afterburners, tail pipes. devices described in .
11. 9. The device of claim 8, wherein the device is an industrial equipment device for use in waste incinerators, boilers, high temperature reactors and rotary calciners, and petrochemical production and synthesis gas plants.
12. In mass %, Ni is 23 to 32%, Co is 37 to 48%, Mo is 8 to 12%, and the balance contains Cr and inevitable impurities,
    20 ≤ [Cr%] + [Mo%] + [% of unavoidable impurities] ≤ 40,
    Prepare a cobalt-chromium alloy material with a composition that satisfies
    Homogenizing the prepared cobalt-chromium alloy material at 1100° C. to 1300° C.,
    The homogenized cobalt-chromium alloy material is subjected to cold plastic working into a tubular or wire shape to obtain an as-processed cobalt-chromium alloy material,
    The as-worked cobalt-chromium alloy material that has been plastically worked by cold is subjected to a heat treatment at a temperature exceeding the recrystallization temperature of the cobalt-chromium alloy material to 1100 ° C. or less for 1 minute or more and 60 minutes or less to obtain a face-centered cubic lattice ( fcc), or a crystal structure consisting of a face-centered cubic lattice (fcc) and a hexagonal lattice (hcp), the average grain size is 2 to 15 μm, and the local crystal orientation A method for producing a cobalt-chromium alloy member, characterized in that the amount of change (KAM value) is 0.0 or more and 1.0 or less.

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