High-strength stainless steel wire for interventional medical treatment and preparation method thereof
阅读说明：本技术 介入医疗用高强度不锈钢丝及其制备方法 (High-strength stainless steel wire for interventional medical treatment and preparation method thereof ) 是由 张绍翔 徐佩 于 2021-08-30 设计创作，主要内容包括：本发明提供一种介入医疗用高强度不锈钢丝,以化学成分为质量百分比计为：C：0.01%-0.09%、Si：0.01%-1.00%、Mn：0.01%-2.00%、P：0.005%-0.05%、S：0.01%-0.30%、Ni：7%-15%、Cr：14%-20%、N：0.01%-0.08%、La+Ce：0.01%-0.5%、Y：0.01%-1%、余量为Fe；其中,Ni当量≤35、且Ni当量=Ni+0.65Cr+0.98Mo+1.05Mn+0.35Si+12.6C。上述不锈钢丝的方法包括：真空熔炼、锻造坯料、拉拔丝材粗坯、丝材拉拔。本发明的立足于上述的化学成分的不锈钢,并保证一定的Ni当量。通过设计道次压缩量、拉拔速度、拉拔温度,获得一定的马氏体体积分数,从而调控强度。并结合拉拔模具、道次截面积压缩量,获得一定晶面取向的马氏体结构。此外,通过稀土元素的细化晶粒作用以及原位自生稀土氮化物的沉淀强化作用,最终获得高强度的钢丝。(The invention provides a high-strength stainless steel wire for interventional medical treatment, which comprises the following chemical components in percentage by mass: c: 0.01% -0.09%, Si: 0.01% -1.00%, Mn: 0.01% -2.00%, P: 0.005% -0.05%, S: 0.01% -0.30%, Ni: 7% -15%, Cr: 14% -20%, N: 0.01% -0.08%, La + Ce: 0.01% -0.5%, Y: 0.01 to 1 percent of Fe and the balance of Fe; wherein the Ni equivalent is less than or equal to 35, and the Ni equivalent = Ni +0.65Cr +0.98Mo +1.05Mn +0.35Si + 12.6C. The method for manufacturing the stainless steel wire comprises the following steps: vacuum melting, blank forging, wire rough blank drawing and wire drawing. The present invention is based on the stainless steel having the above chemical composition, and ensures a certain Ni equivalent. And a certain martensite volume fraction is obtained by designing the pass reduction, the drawing speed and the drawing temperature, so that the strength is regulated and controlled. And combining a drawing die and the pass sectional area reduction amount to obtain a martensite structure with a certain crystal plane orientation. In addition, the high-strength steel wire is finally obtained through the grain refining effect of the rare earth elements and the precipitation strengthening effect of the in-situ authigenic rare earth nitride.)
1. The high-strength stainless steel wire for interventional medical treatment is characterized by comprising the following chemical components in percentage by mass:
C ：0.01%-0.09%、
Si ：0.01%-1.00%、
Mn ：0.01%-2.00%、
P：0.005%-0.05%、
S：0.01%-0.30%、
Ni：7%-15%、
Cr：14%-20%、
N：0.01%-0.08%、
La+Ce：0.01%-0.5%、
Y：0.01%-1%、
the balance being Fe;
wherein the Ni equivalent is less than or equal to 35, and the Ni equivalent = Ni +0.65Cr +0.98Mo +1.05Mn +0.35Si + 12.6C.
2. The high-strength stainless steel wire for interventional medical treatment according to claim 1, wherein: the mass ratio of La to Ce is 1: 100-100: 1.
3. The high-strength stainless steel wire for interventional medical treatment according to claim 1, wherein: the volume percentage content of the alpha' martensite of the stainless steel wire is more than or equal to 60 percent, and the tensile strength of the stainless steel wire is 2200-3500 MPa.
4. The high-strength stainless steel wire for interventional medical treatment according to claim 3, wherein: the martensite crystal orientation of the stainless steel wire forms a texture with dominant orientation of a (200) crystal plane or a (211) crystal plane along the axis of the stainless steel wire, and the transverse section of the stainless steel wire presents an elongated grain shape and presents a spiral arrangement.
5. A method for preparing a high-strength stainless steel wire for interventional medical treatment according to claims 1 to 4, comprising the steps of:
s1, vacuum melting:
supplying predetermined amount of C, Si, Mn, P, S, Ni, Cr%, N%, La, Ce, Y, Fe, vacuum melting at 1500-1600 deg.C with vacuum degree of 0.5-10Pa, and casting into round ingot;
s2, forging blank:
forging the round ingot obtained by the vacuum melting and casting in the step S1 into a round bar with the diameter of 6-20mm, wherein the forging temperature is 500-1000 ℃;
s3, drawing the rough blank of the wire:
drawing the 6-20mm round bar obtained by forging in the step S2 into a wire rough blank of 0.1-5mm, wherein the initial tensile strength range of the wire rough blank is 600MPa-2200 MPa;
s4, drawing the wire:
cooling the rough blank obtained by drawing in the step S3, then drawing for 4-30 times, and finally drawing to obtain a finished stainless steel wire product, wherein the diameter of the finished stainless steel wire product is 0.02-2.0 mm; the drawing temperature is less than or equal to 400 ℃, and the drawing speed is 1-200 m/min;
the cooling method in the step S4 includes one or more combinations of aqueous solution cooling, oily emulsion cooling and air cooling.
6. The method for preparing a high-strength stainless steel wire for interventional medical treatment according to claim 5, wherein: the reduction of the sectional area in each drawing in the step S4 is 5 to 40%, and the reduction of the sectional area =1-d2/d0 2Wherein said d0The initial diameter, d, is the dimension after deformation.
7. The method for preparing a high-strength stainless steel wire for interventional medical treatment according to claim 5, wherein: the opening angle of the drawing die in the step S4 is more than or equal to 10 degrees, the drawing temperature is 20-100 ℃, the drawing speed is 10-100 m/min, and the cooling method is oily emulsion cooling.
8. The method for preparing a high-strength stainless steel wire for interventional medical treatment according to claim 7, wherein: the deformation section of the drawing die is in a torsional state.
Technical Field
The invention relates to the field of medical instruments, in particular to a high-strength stainless steel wire for interventional medical treatment and a preparation method thereof.
Background
With the progress of medical technology and the development of economic society, the number of interventional operations, such as coronary stent implantation, neurovascular stent implantation, peripheral vascular stent implantation, cerebral artery coil implantation and the like, is increasing. And a guide wire is needed in the interventional operation, so that the functions of channel building, radiography, conveying support and the like are achieved. The guide wire generally comprises a core wire, an outer coating and a head, wherein the core wire is the most critical core raw material and plays a role in supporting and guiding. The guide wire which plays a supporting role is generally made of austenitic stainless steel, the diameter is generally between 0.2mm and 1.0mm, the requirements on concentricity and tensile strength are extremely high, and the requirements cannot be met by a common austenitic stainless steel processing method. In addition, batch production is realized by continuous drawing, and the production efficiency and the cost are ensured under the condition of ensuring high strength, so that the integral processing difficulty of the wire is higher.
Research papers and patents of high-strength carbon steel wires in basic research and engineering practice are numerous, and processing methods of high-strength carbon steel wires are described in detail in application No. 200910060815.8, high-carbon steel wires for ultra-fine steel wires and manufacturing methods thereof, and application No. 201310375326.8, methods for producing ultra-fine steel wires from high-carbon steel wires. However, the austenitic steel cannot improve strength by this method due to differences in composition and structure, and may cause problems such as softening and oxidation.
Theoretical research and practice show that important factors influencing the tensile strength of the stainless steel wire rod comprise chemical components, technological conditions such as pass processing amount and cooling effect, and the content of martensite phase generated by processing. Generally, 304 austenitic stainless steels will partially change to the α' martensite phase upon cold working and help increase strength. However, the common wire processing technology is difficult to achieve higher content of the alpha' martensite phase, and particularly the tensile strength is difficult to continue to be improved when the tensile strength is more than 2000 MPa. For example, as reported by smithtang, et al (smithtang, zungsu, maje, heat treatment strengthening mechanism of large deformation of austenitic stainless steel, shanghai metal, 1981, 3(3),29-35), 304 stainless steel can improve the strength to about 2000MPa by the martensite transformation caused by deformation under a certain process. Greater difficulty is encountered in further improvement.
J. Basic studies of the effect of stainless steel wire processing on structure and strength have been reported by-y, Choi, et al, which also found that processing causes a' martensitic transformation and increases strength. (J. -Y. Choi W. Jin, STRAIN INDUCED MARTENSITE FORMATION AND ITS EFFECT ON STRAIN HARDENING BEHAVIOR IN THE COLD DRAWN 304 AUSTENITIC STAINLESS STEELS, Scripta Materialia 36(1) (1997) 99-104.). However, according to the method disclosed by the document, the highest strength of the stainless steel wire is only about 2200MPa, the requirement of the guide wire cannot be met, and the details of the processing technology need to be further optimized.
Wherein the degree of α' martensitic transformation is related to the nickel equivalent of stainless steel:
ni equivalent = Ni +0.65Cr +0.98Mo +1.05Mn +0.35Si +12.6C
The Ni equivalent in a certain range promotes the α' martensitic transformation and thus improves the strength.
U.S. Pat. No. 3,310,310,196 (US patent Number:6,106,639, inventor: Jo ë l Marandel, Varennes-Vauzelles; Jean-Michel Hauser, Ugine) reports a high strength Stainless steel alloy and a method of processing the same. The Cu content in the composition disclosed in the document is 3% -3.5%, and wires with different diameters have different tensile strengths, the highest is 0.2mm wire, and the strength is more than or equal to 2275 MPa. However, although Cu has a strengthening effect, the corrosion of stainless steel is significantly affected, and the element has positive and negative effects and needs to be used carefully.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a high-strength stainless steel wire for interventional medical treatment and a preparation method thereof.
In order to achieve the above object, the present invention provides a high strength stainless steel wire for interventional medical treatment, which comprises the following chemical components by mass percent:
C ：0.01%-0.09%、
Si ：0.01%-1.00%、
Mn ：0.01%-2.00%、
P：0.005%-0.05%、
S：0.01%-0.30%、
Ni：7%-15%、
Cr：14%-20%、
N：0.01%-0.08%、
La+Ce：0.01%-0.5%、
Y：0.01%-1%、
the balance being Fe;
wherein the Ni equivalent is less than or equal to 35, and the Ni equivalent = Ni +0.65Cr +0.98Mo +1.05Mn +0.35Si + 12.6C.
Further, the mass ratio of La to Ce is 1: 100-100: 1.
Further, the volume percentage content of the alpha' martensite of the stainless steel wire is more than or equal to 60 percent, and the tensile strength of the stainless steel wire is 2200-3500 MPa.
Further, the martensite crystal orientation of the stainless steel wire forms a texture with a predominant orientation of (200) plane or (211) plane along the axis of the stainless steel wire, and the transverse cross section of the stainless steel wire exhibits an elongated grain shape and exhibits a helical arrangement.
The invention also provides a preparation method of the high-strength stainless steel wire for interventional medical treatment, which comprises the following steps:
s1, vacuum melting:
supplying predetermined amount of C, Si, Mn, P, S, Ni, Cr%, N%, La, Ce, Y, Fe, vacuum melting at 1500-1600 deg.C with vacuum degree of 0.5-10Pa, and casting into round ingot;
s2, forging blank:
forging the round ingot obtained by the vacuum melting and casting in the step S1 into a round bar with the diameter of 6-20mm, wherein the forging temperature is 500-1000 ℃;
s3, drawing the rough blank of the wire:
drawing the 6-20mm round bar obtained by forging in the step S2 into a wire rough blank of 0.1-5mm, wherein the initial tensile strength range of the wire rough blank is 600MPa-2200 MPa;
s4, drawing the wire:
cooling the rough blank obtained by drawing in the step S3, then drawing for 4-30 times, and finally drawing to obtain a finished stainless steel wire product, wherein the diameter of the finished stainless steel wire product is 0.02-2.0 mm; the drawing temperature is less than or equal to 400 ℃, and the drawing speed is 1-200 m/min;
the cooling method in the step S4 includes one or more combinations of aqueous solution cooling, oily emulsion cooling and air cooling.
Further, in the step S4, the reduction of the sectional area at the time of drawing of each pass is 5% to 40%, and the reduction of the sectional area =1-d2/d0 2Wherein said d0The initial diameter, d, is the dimension after deformation.
Further, the opening angle of the drawing die in the step S4 is more than or equal to 10 degrees, the drawing temperature is 20-100 ℃, the drawing speed is 10-100 m/min, and the cooling method is oily emulsion cooling.
Furthermore, the deformation section of the drawing die is in a torsional state, so that the cross section torsional deformation of the stainless steel wire is promoted, the orientation is improved, and the spiral crystal grains with the cross section oriented preferentially can be obtained.
The invention has the beneficial effects that:
when the martensite crystal plane forms a dominant orientation, the material can present a certain anisotropy, and the tensile strength along the length axis direction is relatively higher, so that the strength can be further improved. The advantage orientation is obtained by controlling technological parameters, including the reduction of the cross-sectional area of the pass and the design of the parameters of the die.
The volume percentage of martensite also directly affects the final tensile strength, which is closely related to the drawing speed, drawing temperature, and cooling conditions.
The microscopic grain structure on the cross section is spirally arranged and has spiral orientation arrangement, so that the circumferential strength can be improved, and the subsequent processing stability and the torsion synchronism can be improved.
Elements such as Ni, Mn, Cr, N, etc. affect the martensitic transformation efficiency and further affect the strength. Therefore, the patent especially limits the total Ni equivalent, and only when the Ni equivalent is less than a certain value, the martensite transformation efficiency can be ensured, and the strengthening effect is further ensured.
La, Ce and Y are all rare earth elements, and the combination of the elements La and Ce can effectively refine the grain size and improve the strength by the synergistic effect with martensite phase transformation. Meanwhile, the form of the inclusion is changed, and the damage effect of the inclusion is obviously reduced. And Y can obviously improve the martensite phase transformation efficiency, improve the volume fraction of martensite to improve the strength, and can also improve the trend of crystal plane optimization orientation. The three rare earths have synergistic effect to improve the strength obviously. In addition, in the smelting process, Ce, La and Y and N form in-situ authigenic nitride precipitates, so that the obvious precipitation strengthening effect is achieved, and the strength is further improved.
In conclusion, the present invention is based on the stainless steel having the above chemical composition and ensures a certain Ni equivalent. On the basis, a certain martensite volume fraction is obtained by designing the pass reduction, the drawing speed and the drawing temperature, so that the strength is regulated and controlled. And a martensite structure with a certain crystal face orientation is obtained by combining a drawing die and the pass sectional area reduction. In addition, the high-strength steel wire is finally obtained through the grain refining effect of the rare earth elements and the precipitation strengthening effect of the in-situ authigenic rare earth nitride.
Drawings
FIG. 1 is a sectional profile picture of a stainless steel wire sample in example 1 along the long axis.
FIG. 2 is a graph showing the wire tensile strength curves of the stainless steel wire samples of example 5.
Fig. 3 is a schematic view of the microstructure of a cross section of a sample of the stainless steel wire in example 1.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that various changes and modifications can be made by those skilled in the art without departing from the spirit of the invention, and these changes and modifications are all within the scope of the invention.
Example (b): examples 1-10 are high strength austenitic stainless steel wires produced by controlled smelting and processing using the compositions and methods of preparation of the present invention, and the chemical composition is shown in table 1.
Table 1: ingredients and performance parameters for examples 1-10.
Example numbering
1
2
3
4
5
6
7
8
9
10
La+Ce%
0.02
0.11
0.48
0.22
0.14
0.37
0.26
0.19
0.43
0.04
Y%
0.02
0.55
0.31
0.14
0.23
0.05
0.46
0.73
0.09
0.98
P %
0.005
0.04
0.017
0.023
0.006
0.035
0.05
0.009
0.016
0.02
S %
0.28
0.01
0.07
0.05
0.25
0.06
0.21
0.17
0.13
0.12
N %
0.07
0.03
0.06
0.05
0.08
0.02
0.01
0.03
0.04
0.01
Ni %
7.8
15
10.1
12.1
9.4
14.6
11.7
9.2
10.5
8.1
Cr%
17
20
18
16
14
19.7
20
17
18
19
Mn%
0.01
1.9
0.53
1.2
0.19
1.87
1.04
1.8
0.07
1.6
Si%
0.01
0.99
0.51
0.05
0.98
0.79
0.95
0.03
0.46
0.25
C%
0.01
0.09
0.06
0.05
0.06
0.09
0.07
0.03
0.07
0.06
Fe
Balance of
Balance of
Balance of
Balance of
Balance of
Balance of
Balance of
Balance of
Balance of
Balance of
Ni equivalent weight
18.99
31.48
23.29
24.41
19.80
30.78
27.01
22.53
23.32
22.97
Diameter mm of rough blank
0.2
2
4
2
3
0.8
5
4
5
1
Initial tensile strength Mpa
2100
1270
792
907
605
1740
893
1562
2179
1579
Drawing pass
4
13
9
11
19
6
24
9
22
10
Amount of pass reduction
6.0%
13.0%
22.1%
13.0%
5.3%
27.9%
17.8%
19.4%
13.4%
32.7%
Diameter of finished product
0.16
0.33
0.42
0.43
1.07
0.11
0.05
0.57
0.21
0.02
Drawing speed m/min
12
47
93
3
175
200
196
47
190
88
Drawing temperature
53℃
42℃
76℃
193℃
88℃
201℃
15℃
21℃
398℃
21℃
Martensite content
75%
67%
91%
79%
83%
66%
92%
68%
81%
94%
Tensile strength Mpa of finished product
2709
2400
2813
2731
2903
2547
3100
2530
2659
3074
In the embodiment, according to the chemical components and the processing technology disclosed by the invention, the martensite content in the microstructure can be greatly improved, so that the strength is improved, the highest strength can reach 3100MPa, and the implementation effect is remarkable.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.