JPH0441640A - Superelastic alloy wire rod for catheter guide wire and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a superelastic alloy wire rod by preparing an alloy constituted of specified ratios of Ni and Ti and in which the stress of the stage part, the apparent elastic modulus and the length of the stage part are specified. CONSTITUTION:An Ni-Ti allay constituted of, by atom, 50.7 to 53.0% Ni and the balance Ti is subjected to base annealing at 450 to 600 deg.C for l0sec to l80min into >=100kgf/mm<2> tensile strength, is successively subjected to wire drawing at >=30% working ratio into >=150kgf/mm<2> tensile strength and is successively subjected to finish annealing at 400 to 60O deg.C for l0sec to 30min into 130 to l90kgf/mm<2> tensile strength, by which the superelastic alloy wire rod for a catheter guide wire having the properties of >=60kgf/mm<2> stress of the prescribed stage part, >=4000 apparent elastic modulus and >=6.0% length of the stage part can be obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a superelastic alloy wire having high generated force, high superelastic strain, and high elastic modulus used in catheter guide wires, etc., and a method for manufacturing the same. be.

[Conventional technology and its issues]

Superelastic alloy wires are used for catheter guidewires inserted into the human body because they require flexibility and strength against bending deformation, that is, appropriate elastic modulus. There are two types of superelastic properties of the superelastic alloy wire used in this catheter guide wire.

As shown in the stress-strain characteristics shown in FIG. 2, Type I has characteristics such as stage part cuff 2 kgf/- apparent elastic modulus 3600 kgf/- and stage part length about 4.0%. This type is characterized by a high force generation type, short superelastic strain at the stage section, that is, under constant stress, and a small apparent elastic modulus. When this superelastic wire is used as a catheter guide wire, when it is passed through a complicated blood vessel, the load increases as the curvature of the blood vessel decreases, and the generated force increases when it exceeds 4%, making it difficult for the wire to pass smoothly. . Therefore, it is not suitable for use in complicated blood vessels with small curvature. It is possible to pass the wire into blood vessels by making the diameter smaller and reducing the force generated, but as shown in the relationship between the apparent elastic modulus and the strength of the waist shown in Figure 3, the strength of the waist is Since it is in a proportional relationship with the elastic modulus, wire rods with such a small elastic modulus are weak and have the disadvantage of being difficult to manipulate at hand.

Next, type II has characteristics of stage part stress of 46.4 kgf/-1, apparent elastic modulus of 4450 kgf/j, and stage part length of about 6.6%, as shown in the stress-strain characteristics shown in Figure 4. , is a low-force type, and is characterized by a long superelastic strain in the stage section and a large apparent elastic modulus. When this wire rod has a small curvature and is passed through a complicated blood vessel, the force generated is small, so it may buckle and not move forward.

For this reason, it is necessary to increase the diameter of the wire, but when the diameter of the wire is increased, there is a problem that it is difficult to pass through complicated and narrow blood vessels with small curvature.

Conventionally, as a manufacturing method for these superelastic alloy wire rods for catheter guide wires, Ni-Ti alloy wire rods are
After performing running annealing at a temperature of 750°C for 1 to 2 minutes, wire drawing is performed at a reduction rate of 30 to 40%, followed by running annealing at a temperature of 500°C to 550°C for 1 to 2 minutes. Inter-annealing was performed.

However, although various studies have been made on the alloy composition and manufacturing method, it has been difficult to obtain a superelastic alloy wire for wires having the above-mentioned flexibility and stiffness, that is, the elastic modulus.

[Problem to be solved by the invention]

The present invention has been made as a result of consideration of the above problems, and has the advantages of both Types I and Type 2. It has a high generated force, that is, a high stage stress, a large apparent elastic modulus, and a long stage length. We have developed a superelastic alloy wire material for catheter guide wires with special characteristics and a method for manufacturing the same.

[Means and effects for solving the problem] The present invention has N
i 50.7 to 53.0 at%, the balance being Ti,
A superelastic alloy wire material for a catheter guide wire, which is characterized by having a stage part stress of 60 kgf/mm2 or more, an apparent elastic modulus of 4000 or more, and a stage part length of 6.0% or more. 0a
t%, T i 49.3-47. Part of Oae% of Ni or/and Ti is replaced with Cr, Fe, Co, Mo, V
, Pd, W, or Cu, IW! Or two or more types each (
The stage part stress is 60 kgf/mm2 or more, and the apparent elastic modulus is 4.
000 or more, and the stage length is 6.0% or more, and the superelastic alloy wire material has a N i 50.7-53. Oa
t%, the balance being Ti, is annealed at a temperature of 450°C to 600°C for 10 seconds to 180 minutes to obtain a tensile strength of 100 kgf/mm2 or more, and then the processing rate is 30%.
The tensile strength was increased to 150kgf/mm after the above wire drawing process.
2 or more, then 400℃ to 60 (10℃ at a temperature of 1℃)
Final annealing is performed for seconds to 30 minutes to increase the tensile strength to 130~
190 kgf/mm2, a method for producing a superelastic alloy wire for a catheter guide wire, further comprising N450.7 to 53.0 at% and T i 49.3.
~47.0at% of Ni or/and a part of Ti is replaced with C
Any one of r5Fe, Co, M01V, Pd, W, Cu
An alloy formed by substituting one species or two or more species in the range of 0.01 to 5.0 at% each is annealed at a temperature of 450°C to 600°C for 10 seconds to 180 minutes to obtain a tensile strength of 100 kgf.
/mm2 or more, followed by wire drawing at a processing rate of 30% or more to achieve a tensile strength of 150 kgf/mm2 or more, and then finish annealing at a temperature of 400°C to 600°C for 10 seconds to 30 minutes to obtain a tensile strength. Strength 130~190kgf
/mm2.

That is, in the present invention, N i 50.7 to 53.0 at%
, Ni-Ti alloy with balance Ti or Ni 50
．． 7-53.0 at%, Ti 49.3-47.0a
Part of t% of Ni or/and Ti is replaced with Cr, Fe, C
o, Mo, V, Pd, W.

Any one type or two or more types of Cu from 0.01 to 5.0 each
By performing specific material annealing, wire drawing and finish annealing as described above to the Ni-Ti alloy substituted within the range of at%, the stress at the stage part is 60 kgf/mm.
A superelastic alloy wire for a catheter guide wire having characteristics of 2 or more, an apparent elastic modulus of 4000 or more, and a stage length of 6.0% or more was obtained.

Further, the present invention provides the above-mentioned specific Ni-Ti alloy or N
i-Ti alloy at a temperature of 450°C to 600°C for 10 seconds
The material was annealed for 180 minutes to achieve a tensile strength of 100 kg.
f/mm2 or higher, followed by wire drawing at a processing rate of 30% or higher to achieve a tensile strength of 150 kgf/mm2 or higher, followed by final annealing at a temperature of 400°C to 600°C for 10 seconds to 30 minutes. tensile strength of 130 to 190 kgf
/-, the predetermined stage stress is 60 kgf.
The object of the present invention is to obtain a superelastic alloy wire for a catheter guide wire having characteristics of /mm2 or more, an apparent elastic modulus of 4000 or more, and a stage length of 6.0% or more.

Therefore, the alloy composition of the present invention is Ni50.7-53.0a.
t% and the remainder Tj is because Ni is 50.7a. If the Ni content is less than t%, the tensile strength after final annealing is 130 to 190k.
This is because even if gf/- is satisfied, the higher the transformation point, the lower the stress in the stage part and the lower the apparent elastic modulus, which poses a practical problem.
This is because if it exceeds at%, wire drawing becomes difficult.

Also, N i 50.7 to 53.0 at%, T i 49
．． 3 to 47.0 at% of Ni or/and a part of Ti is replaced with any one or more of Cr, Fe, COlMo, V, Pd, W, and Cu in the range of 0.01 to 5.0 at% each. The reason for replacing these elements with This is because if it exceeds 5.0 at%, processability will deteriorate.

In the manufacturing method of the present invention, the conditions for annealing the material are 450°C ~
The reason why the wire is annealed at a temperature of 600°C for 10 seconds to 180 minutes is that by annealing in this range, the processed structure is left in the wire and the tensile strength is 100 kgf/mm2 or more. This is because the tensile strength after wire drawing does not exceed 150 kgf/mm2, and high stage stress cannot be obtained.

Next, we set the wire drawing rate to 30% or more by applying strong processing to the wire rod through this wire drawing process, increasing the tensile strength of the wire rod to 150%.
This is to make it kgf/-.

In addition, finish annealing is performed at a temperature of 400°C to 600°C for 10 seconds.
The reason for the annealing time of 30 minutes is that this annealing allows the processed structure from the wire drawing in the previous process to remain to some extent, increasing the tensile strength to 130~130 minutes.
The tension is maintained at 190 kgf/-, and the apparent elastic modulus and length of the stage section are adjusted to desired ranges.

The reason why the tensile strength immediately after the processes such as fabric annealing, wire drawing, and finish annealing is limited as above is to use as a guideline to see the degree of remaining processed structure due to annealing and wire drawing. This is because unless the treatment is performed so that the tensile strength after each step is within the above range, the desired characteristics such as stage stress, apparent elastic modulus, and stage length will not be obtained.

Although the reasons for the above-mentioned fabric annealing, wire drawing, and final annealing steps and the effect of improving superelastic properties are not clear, it is thought that it is due to the reasons described below.

(2) As the amount of Nl increases, the transformation point decreases, thereby increasing the stress in the stage section.

■By leaving a processed structure in the material annealing, the tensile strength after the final wire drawing is increased, which increases the stress in the stage section.

〔Example〕

An embodiment of the present invention will be described below.

Using Ni-Ti alloys and Ni-Ti alloy wires having the composition shown in Table 1, the material was annealed at 500°C for 21 minutes, then wire-drawn at a processing rate of 40%, and then at 520°C for 1 minute. Finish annealing was performed. A tensile test was conducted on the wire after each of these steps to measure the tensile strength. The results are shown in Table 1.

Stress-strain characteristics, which is a method for evaluating superelastic properties, were measured for the sample NO.1. The results are shown in FIG.

Note that the apparent elastic modulus is the value obtained by performing a tensile test on a 0.5 mφ wire, determining the apparent yield stress σ7, and dividing this by the strain ε.

As is clear from the figure, the stress generated in the stage section (yield stress) is 68 kgf/- when loaded (strain 1.6 to 7%) and 36 kgf/- when unloaded (strain 0.8 to 5.6%). Then,
The wire rod of the present invention has the same stage stress as the conventional wire rod type (Fig. 2), but the length of the stage portion, that is, the superelastic modulus under a constant load. The amount of strain is large, and the length is approximately twice as long.Also, when compared with type ① (Fig. 4), the stage part length is about the same, but the stage part stress is 46 kgf/-
It can be seen that the power generated is approximately 40% larger, and the force generated is large, covering the drawbacks of the conventional types I and H.

Next, the stress-strain characteristics of the wire rods in Table 1 were determined in the same manner as above, and the results of investigating the characteristics such as stage part stress, stage part length, apparent elastic modulus, shape recovery property, etc., and workability are shown in Table 2. Shown in the table.

■The tensile strength after final annealing is (i) and (ii) (
2) Regarding the final annealing conditions, that is, from ■, the tensile strength after annealing the material is 100 kgf.
/-, the tensile strength after wire drawing is 150 kgf/
- cannot be obtained, and according to (■), if the tensile strength after wire drawing is less than 150 kgf/-, a tensile strength of 130 kgf/- after final annealing cannot be obtained, and from the results of (■), the tensile strength after annealing is less than 150 kgf/-. Even if it is smaller than 130-190kgf/-,
Either of the superelastic properties is bad, no matter how large. As is clear from Table 2, all of the samples of grades 1 to N114 of the present invention have good stage part stress, stage part length, apparent elastic modulus, shape recovery property, and workability. On the other hand, NCL5, which has a small amount of Ni, has good stage length but poor other characteristics. Also, N [L6
The wire could not be drawn and a wire rod could not be obtained. Next, the dough is annealed,
The results of investigating the tensile strength and superelastic properties after wire drawing and final annealing are as follows.

(1) Regarding tensile strength ■ If the tensile strength after annealing the fabric is 70kgf/-↓ If the tensile strength after wire drawing is 140kgf/- (<150kg
f/d)■ If the tensile strength after wire drawing is 140kgf/-↓ The tensile strength after final annealing is (550'CX 1 minute) 11
5 kgf/wJ (<130 kgf/d) and the results in (2) indicate that if the finish annealing conditions are outside the range of the present invention, some of the superelastic properties are inferior.

[Effect] As explained above, according to the present invention, it has a high generated force,
A superelastic base metal wire having a long superelastic strain under constant stress and an apparent elastic modulus can be obtained, and is suitable as a material for catheter guide wires and the like, and has a remarkable industrial effect.

[Brief explanation of the drawing]

FIG. 1 is a graph showing stress-strain characteristics of a superelastic alloy wire for a catheter guide wire according to an embodiment of the present invention. Second
FIG. 4 is a graph showing the stress-strain characteristics of a conventional superelastic alloy wire for catheter guide wires. FIG. 3 is a graph showing the relationship between stiffness and apparent elastic modulus of a superelastic alloy wire. Patent Applicant Agent Patent Attorney Yu Meiki - Figure 6 Figure 2 Figure 4

Claims (4)

[Claims] (1) It is composed of 50.7 to 53.0 at% Ni and the balance is Ti, and has the characteristics of a stage part stress of 60 kgf/mm^2 or more, an apparent elastic modulus of 4000 or more, and a stage part length of 6.0% or more. Superelastic alloy wire material for catheter guide wires. (2) Ni50.7~53.0at%, Ti49.3~
Part of 47.0at% of Ni or/and Ti is replaced with Cr
, Fe, Co, Mo, V, Pd, W, and Cu in a range of 0.01 to 5.0 at% each, and the stage part stress is 60 kgf/mm^2 or more. , apparent elastic modulus of 4000 or more, stage length 6.
1. A superelastic alloy wire for catheter guide wires, characterized by having a property of 0% or more. (3) An alloy consisting of 50.7 to 53.0 at% Ni and the balance Ti was annealed at a temperature of 450 to 600 °C for 10 seconds to 180 minutes to achieve a tensile strength of 100 kgf/mm^
2 or higher, followed by wire drawing at a processing rate of 30% or higher to achieve a tensile strength of 150 kgf/mm^2 or higher, and then finish annealing at a temperature of 400°C to 600°C for 10 seconds to 30 minutes. Tensile strength 130-190kgf/mm^
2. A method for producing a superelastic alloy wire for a catheter guide wire, characterized in that: (4) Ni50.7~53.0at%, Ti49.3~
Part of 47.0at% of Ni or/and Ti is replaced with Cr
, Fe, Co, Mo, V, Pd, W, and Cu at a temperature of 450°C to 600°C. 10 seconds~
The material was annealed for 180 minutes to achieve a tensile strength of 100 kgf/
mm^2 or more, followed by wire drawing at a processing rate of 30% or more to achieve a tensile strength of 150 kgf/mm^2 or more, and then finish annealing at a temperature of 400°C to 600°C for 10 seconds to 30 minutes. The tensile strength is 130 to 190 kgf.
/mm^2. A method for producing a superelastic alloy wire for a catheter guide wire.