An ultrafine stainless steel microfilament and a preparation method thereof

Abstract

The present invention provides an ultra-fine stainless steel micro wire, and its chemical composition by mass percentage includes: C: 0.01% - 0.03%, Ni: 3.0% - 4.0%, Cr: 22% - 26%, Ti: 0.1% - 0.3%; N: 0.1% - 0.3%, Mo: 0.15% - 0.20%; W: 0.60% - 0.70%, V: 0.15% - 0.20%, and the balance is Fe and inevitable impurities. Through the optimization of the stainless steel rolling process and the exploration of the bunch drawing process in this application, the wire breakage rate is reduced, and stainless steel micro wires with high strength, corrosion resistance, and excellent impact toughness are prepared, having a market promotion prospect. Under the preferred conditions, when the drawing strength reaches 1800 MPa and the wire diameter is 0.01 μm, the corrosion resistance is excellent and the impact toughness is 30 J.

Description

Technical Field

[0001] The present invention relates to the technical field of metal materials, and particularly relates to a high-strength heat-resistant ultra-fine stainless steel micro-wire and a preparation method thereof. Background Art

[0002] The unique preparation process of stainless steel micro-wires has caused significant changes in the product structure and performance in many aspects, such as electrical conductivity, thermal conductivity, corrosion resistance, high wear resistance, stable surface properties, high strength and high ductility, as well as excellent radiation protection, super-strong shielding effect on electromagnetic interference, and good sound absorption effect. Therefore, stainless steel micro-wires are widely used in modern industries such as petrochemical, textile, metallurgy, automotive manufacturing, construction, medicine, biochemistry, national defense, and aerospace, and modern civil industries, for making high-precision filter wire meshes, shielding and sound-absorbing equipment, microwave absorption devices, battery electrodes, fiber composite reinforcement materials, protective clothing, etc. Even due to the significant changes in its microstructure and the nano-scale grain size effect, there have emerged some new additional characteristics that the raw materials do not have, all of which provide a broad space for expanding the application fields of stainless steel metal micro-wires.

[0003] Currently, the raw materials used for producing micro-wires are mainly low-carbon and ultra-low-carbon stainless steels. Generally, stainless steel wires are based on stainless steels such as 304, 304L, or 316, 316L, etc. However, there are few stainless steel micro-wires prepared from duplex stainless steel on the market, and duplex stainless steel wires can provide better mechanical strength. And the traditional rolling process is prone to wire breakage problems.

[0004] However, there are some defects in the existing alloying schemes. For example, improper selection of alloying elements leads to limited performance improvement, or the alloy cost is too high, affecting industrial application. Therefore, there is an urgent need to develop a new type of high-strength heat-resistant ultra-fine stainless steel micro-wire. By optimizing the types and contents of alloying elements, while ensuring good corrosion resistance, the strength and elongation are significantly improved, so as to meet the actual needs of industrial production. Summary of the Invention

[0005] Aiming at the deficiencies in the mechanical properties, impact toughness, and corrosion resistance of the existing stainless steel micro-wires, as well as the defects in the optimized alloying scheme and the high cost, etc.

[0006] On the one hand, the present invention provides an ultra-fine stainless steel micro-wire. The chemical composition of the ultra-fine stainless steel micro-wire by mass percentage includes: C: 0.01% - 0.03%, Ni: 3.0% - 4.0%, Cr: 22% - 26%, Ti: 0.1% - 0.3%; N: 0.1% - 0.3%, Mo: 0.15% - 0.20%; W: 0.60% - 0.70%, V: 0.15% - 0.20%, and the balance is Fe and inevitable impurities;

[0007] The wire diameter of the stainless steel wire is 50 μm or less;

[0008] The ultrafine stainless steel micro wire is prepared by the following preparation method, and the preparation method includes the following steps:

[0009] Step 1: According to the composition of the ultrafine stainless steel micro wire, ingredients are proportioned, and through smelting and casting, a billet is obtained; the billet is subjected to homogenization treatment; then the heat-insulated billet starts continuous rolling until the target diameter; after hot rolling, annealing is carried out according to the conventional process, and finally a semi-finished wire rod is obtained;

[0010] Step 2: The semi-finished wire rod is loaded into a copper tube, compacted, and then drawn, followed by annealing treatment to soften the stainless steel wire for the drawing of the next process; through repeated drawing and annealing, the diameter of the required fiber is obtained, namely the ultrafine stainless steel micro wire.

[0011] Preferably, in Step 1, the homogenization temperature is controlled at 1100°C - 1150°C, and the treatment time is 3 - 5 hours.

[0012] Preferably, in Step 1, the starting rolling temperature is controlled at 1000°C - 1200°C, and the final rolling temperature is 900°C - 960°C.

[0013] Preferably, in Step 1, the target diameter is 0.01 mm - 0.05 mm; the annealing temperature is controlled at 800°C - 900°C.

[0014] Preferably, in Step 2, the diameter of the copper tube is 50 mm, and the number of cores in the copper tube is controlled at 800 - 900 cores.

[0015] Preferably, in Step 2, the annealing temperature is 700°C - 800°C, and the annealing speed is 10 m / min - 20 m / min.

[0016] Preferably, in Step 2, the pass reduction is 40% - 50%.

[0017] Preferably, the chemical composition of the ultrafine stainless steel micro wire by mass percentage includes: C: 0.025%, Ni: 3.8%, Cr: 25%, Ti: 0.25%; N: 0.17%, Mo: 0.17%; W: 0.68%, V: 0.17%, and the balance is Fe and unavoidable impurities.

[0018] Preferably, the wire diameter of the stainless steel wire is 10 μm or less.

[0019] In the second aspect, the present application provides an application of the above-mentioned ultrafine stainless steel micro wire in the fields of medical devices, aerospace, automobiles, and electronic products.

[0020] The ultrafine stainless steel micro wire provided by the present application has the following functions:

[0021] 1) The ultra-fine stainless steel microfilaments prepared by the present invention have a wire diameter of 50 μm or less by controlling the component content of the alloy and the preparation process. Through the synergistic effect of Ni-Cr-Ti elements in the formula, while ensuring the stability of the grains, intergranular corrosion is reduced, and the raw material cost is lowered. The addition of W-V can prevent the abnormal growth of austenite grains, refine the grains during solution treatment, and meet the production process of stainless steel filaments. At the same time, it makes up for the reduction in corrosion resistance and increases the elongation rate. Tungsten is a corrosion-resistant element. Appropriate addition of tungsten can replace part of the corrosion-resistant function of molybdenum, thereby reducing the alloy cost.

[0022] 2) Through the optimization of the stainless steel rolling process and the exploration of the bunch drawing process in this application, the wire breakage rate is reduced, and stainless steel microfilaments with high strength, corrosion resistance, and excellent impact toughness are prepared, which have market promotion prospects. Specific embodiments

[0023] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0024] In order to illustrate the technical solution of the present invention, it will be described below through specific embodiments.

[0025] In the first aspect, the chemical composition of the ultra-fine stainless steel microfilaments provided by this application includes, by mass percentage: C: 0.01% - 0.03%, Ni: 3.0% - 4.0%, Cr: 22% - 26%, Ti: 0.1% - 0.3%; N: 0.1% - 0.3%, Mo: 0.15% - 0.20%; W: 0.60% - 0.70%, V: 0.15% - 0.20%, and the balance is Fe and unavoidable impurities;

[0026] In the ultra-fine stainless steel microfilaments, C is an austenitizing element. Adding an appropriate amount of C content to less than 0.01% will cause a decrease in the tensile strength and impact toughness of the stainless steel wire. When the C content exceeds 0.03%, carbides of elements such as Cr and C are likely to form at the grain boundaries, increasing the tendency of intergranular corrosion cracking. Therefore, the C content is controlled within the range of 0.01% - 0.03%.

[0027] Ni is an austenite stabilizing element. The passivation effect of nickel is very strong, and it can significantly improve the corrosion resistance, tensile strength, and impact toughness in combination with chromium. However, too high Ni content will increase the alloy cost. Therefore, the Ni content is controlled within the range of 3.0% - 4.0%. While reducing the cost, the reduction in the nickel content will lead to a decrease in the corrosion resistance of the stainless steel wire.

[0028] Cr is the main corrosion-resistant element. Appropriately increasing the Cr content can improve the corrosion resistance. However, too high a Cr content will reduce the austenite stability. Therefore, the Cr content is controlled within the range of 22% - 26%.

[0029] The increase of Ti element is mainly to prevent the excessive increase of chromium element content, which is likely to form the precipitation of Cr23C6 at grain boundaries and inhibit intergranular corrosion. Therefore, the Ti content is controlled within the range of 0.1% - 0.3%.

[0030] N is a strengthening element. Appropriate addition of nitrogen can significantly improve the strength of the material. However, too high a nitrogen content will reduce the corrosion resistance. Therefore, the nitrogen content is controlled within the range of 0.1% - 0.3%.

[0031] Mo is the main corrosion-resistant element. Appropriate addition of molybdenum can improve the corrosion resistance. However, too high a molybdenum content will increase the alloy cost. Therefore, the Mo content is controlled within the range of 0.15% - 0.20%. The synergy of molybdenum / tungsten can increase the elongation.

[0032] The addition of W and V can prevent the abnormal growth of austenite grains, refine the grains during solution treatment, which is in line with the production process of stainless steel fine wires. At the same time, it makes up for the reduction of corrosion resistance and increases the elongation. Therefore, the vanadium content is controlled within the range of 0.05% - 0.25%. W is a corrosion-resistant element. Appropriate addition of tungsten can replace part of the corrosion-resistant effect of molybdenum, thereby reducing the alloy cost. However, too high a tungsten content will affect the austenite stability. Therefore, the tungsten content is controlled within the range of 0.60% - 0.70%.

[0033] The ultra-fine stainless steel micro-wires are prepared by the following preparation method, and the preparation method includes the following steps:

[0034] Step 1: Weigh the raw materials of each alloy element in excess according to the composition of the ultra-fine stainless steel micro-wires and add them to a high-temperature converter. Obtain a continuous casting billet through converter smelting, LF refining, RH or VD degassing, electromagnetic stirring, and continuous casting. By controlling the relevant parameters of converter smelting, LF refining, RH or VD degassing, and performing real-time sampling and analysis on the molten steel in the furnace, pour out the molten steel for electromagnetic stirring and continuous casting when each element component reaches the preset value / range.

[0035] Specifically, weigh the raw materials of each alloy element in excess according to the alloy composition and add them to a high-temperature converter. Obtain a continuous casting billet through converter smelting, LF refining, RH or VD degassing, electromagnetic stirring, and continuous casting. By controlling the relevant parameters of converter smelting, LF refining, RH or VD degassing, and performing real-time sampling and analysis on the molten steel in the furnace, pour out the molten steel for electromagnetic stirring and continuous casting when each element component reaches the preset value / range.

[0036] Step 2: Load the semi-finished coil rod into a copper tube, compact it, then perform drawing and subsequent annealing treatment to soften the stainless steel wire for the drawing of the next process. Obtain the ultra-fine stainless steel micro-wires by repeatedly drawing and annealing to reach the required fiber diameter.

[0037] Bundle drawing

[0038] The metal fiber itself is an important functional material. Bundle drawing is the main method for the engineering preparation of micron-scale metal fibers at present. It draws dozens or even tens of thousands of metal wires wrapped in a cylinder, realizing simultaneous reduction in diameter of multiple wires. When the desired fiber diameter is reached, the coating tube is peeled off and the fibers are separated.

[0039] In some embodiments, the homogenization temperature in Step 1 is controlled at 1100°C - 1150°C, and the treatment time is 3 - 5 hours.

[0040] In the preferred embodiment, the homogenization temperature in Step 1 is controlled at 1100°C, and the treatment time is 5 hours.

[0041] In some embodiments, the starting rolling temperature in Step 1 is controlled at 1000°C - 1200°C, and the finishing rolling temperature is at 900°C - 960°C.

[0042] In the preferred embodiment, the starting rolling temperature in Step 1 is controlled at 1180°C, and the finishing rolling temperature is at 960°C.

[0043] In some embodiments, the target diameter in Step 1 is 0.01mm - 0.05mm; the annealing temperature is controlled at 800°C - 900°C.

[0044] In the preferred embodiment, the target diameter in Step 1 is 0.01mm; the annealing temperature is controlled at 900°C.

[0045] Through the exploration of the rolling process in Step 1, in the homogenization treatment, the reasonable performance of temperature and time is that alloy elements are more evenly distributed. Especially in the high-chromium system, it can eliminate composition segregation and non-uniform microstructure, play the role of stabilizing grains and refining grains, and obtaining semi-finished wire rods with specified wire diameters provides the possibility for the next-step bundle drawing to prepare ultra-fine wires.

[0046] In some embodiments, the diameter of the copper tube in Step 2 is 50mm, and the number of cores in the copper tube is controlled at 800 - 900 cores.

[0047] In the preferred embodiment, the number of cores in the copper tube in Step 2 is controlled at 900 cores.

[0048] In some embodiments, the annealing temperature in Step 2 is 700°C - 800°C, and the annealing speed is 10m / min - 20m / min.

[0049] In the preferred embodiment, the annealing temperature in Step 2 is 800°C, and the annealing speed is 20m / min.

[0050] In some embodiments, the pass reduction in Step 2 is 40% - 50%.

[0051] Through the exploration of the rolling process in Step 2, the multi-pass drawing process can achieve a wire diameter ranging from 0.05 mm to 50 μm, increasing the single-pass reduction rate; compared with the traditional multi-mode drawing process, the copper tube encapsulation reduces the number of annealing times; and it can reduce the wire breakage rate.

[0052] In a preferred embodiment, the chemical composition of the ultra-fine stainless steel micro wire by mass percentage includes: C: 0.025%, Ni: 3.8%, Cr: 25%, Ti: 0.25%; N: 0.17%, Mo: 0.17%; W: 0.68%, V: 0.17%, and the balance is Fe and inevitable impurities.

[0053] In some embodiments, the chemical composition of the ultra-fine stainless steel micro wire by mass percentage includes: C: 0.022%, Ni: 3.5%, Cr: 24%, Ti: 0.2%; N: 0.18%, Mo: 0.18%; W: 0.65%, V: 0.18%, and the balance is Fe and inevitable impurities.

[0054] In some embodiments, the chemical composition of the ultra-fine stainless steel micro wire by mass percentage includes: C: 0.03%, Ni: 4%, Cr: 23%, Ti: 0.2%; N: 0.2%, Mo: 0.2%; W: 0.7%, V: 0.17%, and the balance is Fe and inevitable impurities.

[0055] In some embodiments, the wire diameter of the stainless steel wire is below 10 μm.

[0056] In a preferred embodiment, the wire diameter of the stainless steel wire is 10 μm.

[0057] In a second aspect, the present application provides an application of the above ultra-fine stainless steel micro wire in the fields of medical devices, aerospace, automobiles, and electronic products.

[0058] The present invention will be further described below through examples. Example 1

[0059] The present invention provides a method for preparing ultra-fine stainless steel micro wire, and its chemical composition by mass percentage includes: C: 0.025%, Ni: 3.8%, Cr: 25%, Ti: 0.25%; N: 0.17%, Mo: 0.17%; W: 0.68%, V: 0.17%, and the balance is Fe.

[0060] First, the raw materials of the above chemical composition are proportioned and melted into molten steel in a vacuum induction electric furnace. Then, the molten steel is continuously cast into a billet. The billet is subjected to homogenization treatment, that is, the billet is heated to 1100 °C and held for 5 hours.

[0061] Then, hot rolling is carried out on the blank. The starting rolling temperature is 1180 °C, the final rolling temperature is 960 °C, the annealing temperature is controlled at 900 °C, and it is rolled into a semi-finished wire rod with a thickness of 0.01 mm.

[0062] Finally, the semi-finished wire rod is loaded into a copper tube with a diameter of 50 mm, and the number of cores in the copper tube is controlled at 900 cores; for drawing, the loaded copper tube is compacted and then drawn. When the deformation amount reaches 50%, annealing treatment is carried out to soften the stainless steel wire for the drawing of the next process; when the deformation amount reaches 50% again during the second drawing, annealing treatment is carried out again, the annealing temperature is 800 °C, and the annealing speed is 20 m / min; after drawing 6 times and annealing, a stainless steel micro-wire with a wire diameter of 10 μm is obtained. Example 2

[0063] Most of the steps in this example are the same as those in Example 1. The differences are: C: 0.022%, Ni: 3.5%, Cr: 24%, Ti: 0.2%; N: 0.18%, Mo: 0.18%; W: 0.65%, V: 0.18%. Example 3

[0064] Most of the steps in this example are the same as those in Example 1. The differences are: C: 0.03%, Ni: 4%, Cr: 23%, Ti: 0.2%; N: 0.2%, Mo: 0.2%; W: 0.7%, V: 0.17%. Example 4

[0065] Most of the steps in this example are the same as those in Example 1. The difference is: after drawing 5 times and annealing, a stainless steel micro-wire with a wire diameter of 50 μm is obtained. Example 5

[0066] Most of the steps in this example are the same as those in Example 1. The difference is: after drawing 5 times and annealing, a stainless steel micro-wire with a wire diameter of 40 μm is obtained. Example 6

[0067] Most of the steps in this example are the same as those in Example 1. The difference is: the blank is subjected to homogenization treatment, that is, the blank is heated to 900 °C and held for 3 hours. Example 7

[0068] Most of the steps in this example are the same as those in Example 1. The differences are: hot rolling is carried out on the blank, the starting rolling temperature is 1000 °C, and the final rolling temperature is 900 °C. Example 8

[0069] Most of the steps in this example are the same as those in Example 1. The difference is: during the bunch drawing process, the annealing temperature is 700 °C and the annealing speed is 30 m / min.

[0070] Comparative Example 1

[0071] Most steps of this comparative example are the same as those of Example 1, the difference being that V is not added.

[0072] Comparative Example 2

[0073] Most steps of this comparative example are the same as those of Example 1, the difference being that W is not added.

[0074] Comparative Example 3

[0075] Most steps of this comparative example are the same as those of Example 1, the difference being that Ti is not added.

[0076] Comparative Example 4

[0077] Most steps of this comparative example are the same as those of Example 1, the difference being that Ni: 3.5%, Cr: 15%.

[0078] Performance Test

[0079] The ultrafine stainless steel microfilaments prepared in the above examples and comparative examples were tested as follows.

[0080] 1) Wire diameter

[0081] After being magnified by a high-precision metallographic microscope (NIS-Elements), the edges were automatically identified by software and the diameter was calculated.

[0082] 2) Mechanical test

[0083] The mechanical properties of the specimens were tested for tensile strength and elongation by a SANA CMT8102 electronic universal tensile testing machine. A computer connected to the electronic universal tensile testing machine automatically generated a force-displacement curve by taking points during the drawing process, and the elongation was also directly generated by the computer. The gauge length of the specimens was 250 mm and the drawing rate was 250 mm / min.

[0084] 3) Impact toughness

[0085] According to GB / T 1817-2017, it was tested by a pendulum experiment. The specimens had to be treated with borax and should have no scratches, cracks, burrs or other dirt. The experiment was carried out at room temperature. 50 specimens were in a group and 5 groups were tested in parallel and the average value was taken.

[0086] 4) Corrosion resistance

[0087] The corrosion resistance was tested through a smoke experiment. A 5% NaCl solution was prepared, and the pH value of the solution was tested between 6.5 - 7.2 at a temperature of 36°C. Ten to twenty ultra-fine stainless steel wires were arranged in parallel, and both ends were fixed with polyimide tape to form a 1×1 cm² grid (spacing 0.5 mm). It was cleaned in isopropanol for 5 minutes to remove surface grease and rinsed 3 times with deionized water. The mass loss was recorded.

[0088] The above test results are shown in Table 1.

[0089] Table 1

[0090] Group Stainless steel micro wire diameter (μm) Tensile strength (MPa) Elongation rate (%) Impact toughness (J) Corrosion resistance (μg) Example 1 10 1800 25 30 0.38 Example 2 10 1600 26 28 0.43 Example 3 10 1400 29 24 0.51 Example 4 50 1300 35 20 0.39 Example 5 40 1500 30 23 0.47 Example 6 10 1200 20 19 0.95 Example 7 10 1300 21 18 0.73 Example 8 10 1100 20 16 0.63 Comparative example 1 10 920 10 18 1.20 Comparative example 2 10 980 13 19 1.50 Comparative example 3 10 870 20 15 1.60 Comparative example 4 10 830 16 10 0.63

[0091] Combined with Comparative Examples 1 - 8, it can be seen that Example 1 has stronger mechanical properties and clustering toughness. The alloy formula and preparation process are both optimal. In the preparation process, temperature and time will affect the properties of the finally prepared stainless steel micro-wires.

[0092] Combined with Comparative Example 1 and Comparative Example 1, it can be seen that when vanadium element is not added, it will seriously affect the drawing strength and impact toughness of the prepared stainless steel micro-wires, and will also exacerbate intergranular corrosion, with a mass loss reaching 1.2 μg. From Comparative Example 2, it can be seen that tungsten element mainly affects intergranular corrosion and will also reduce mechanical properties due to the synergistic effect. From Comparative Example 3, it can be seen that titanium element is also the main element affecting mechanical properties and intergranular corrosion and is essential in the alloy formula. From Comparative Example 4, it can be seen that reducing the content of chromium element mainly affects the mechanical properties of stainless steel micro-wires.

[0093] In summary, the stainless steel micro-wires produced by the alloy formula and preparation method provided by the present invention have a drawing strength of 1800 MPa under preferred conditions. When the wire diameter is 0.01 μm, they have excellent corrosion resistance and an impact toughness of 30 J. By improving the element content, pass deformation amount, and solution temperature on the basis of the original process, products with excellent properties are obtained. The process is simple and suitable for industrial production.

[0094] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention and should all be included within the protection scope of the present invention.

Claims

1. An ultra-fine stainless steel micro wire, characterized in that, The chemical composition of the ultra-fine stainless steel micro-wire by mass percentage includes: C: 0.01% - 0.03%, Ni: 3.0% - 4.0%, Cr: 22% - 26%, Ti: 0.1% - 0.3%; N: 0.1% - 0.3%, Mo: 0.15% - 0.20%; W: 0.60% - 0.70%, V: 0.15% - 0.20%, and the balance is Fe and inevitable impurities; The wire diameter of the ultra-fine stainless steel micro-wire is below 50 μm; The ultra-fine stainless steel micro-wire is obtained by the following preparation method, and the preparation method includes the following steps: Step 1: Weigh materials according to the composition of the ultra-fine stainless steel micro-wire, and obtain a casting blank through smelting and casting; homogenize the casting blank; then start continuous rolling of the heat-insulated casting blank until the target diameter; after hot rolling, perform annealing according to the conventional process to finally obtain a semi-finished coil rod; The homogenization temperature is controlled at 1100°C - 1150°C, and the treatment time is 3 - 5 hours; Step 2: Load the semi-finished coil rod into a copper tube, compact it, then perform drawing, and then annealing treatment to soften the stainless steel wire for the drawing of the next process; achieve the required fiber diameter through repeated drawing and annealing to obtain the ultra-fine stainless steel micro-wire; The reduction per pass in Step 2 is 40% - 50%; The annealing temperature in Step 2 is 700°C - 800°C, and the annealing speed is 10 m / min - 20 m / min; The diameter of the copper tube is 50 mm, and the number of cores in the copper tube is controlled at 800 - 900 cores.

2. The ultra-fine stainless steel microfilament according to claim 1, wherein The starting rolling temperature in Step 1 is controlled at 1000°C - 1200°C, and the final rolling temperature is 900°C - 960°C.

3. The ultra-fine stainless steel micro wire according to claim 1, wherein The target diameter in Step 1 is 0.01 mm - 0.05 mm; the annealing temperature is controlled at 800°C - 900°C.

4. The ultra-fine stainless steel microfilament according to claim 1, characterized in that, The chemical composition of the ultra-fine stainless steel micro-wire by mass percentage includes: C: 0.025%, Ni: 3.8%, Cr: 25%, Ti: 0.25%; N: 0.17%, Mo: 0.17%; W: 0.68%, V: 0.17%, and the balance is Fe and inevitable impurities.

5. The ultra-fine stainless steel microfilament according to claim 1, characterized in that, The wire diameter of the stainless steel wire is below 10 μm.

6. The application of the ultra-fine stainless steel micro-wire according to any one of claims 1 - 5 in the fields of medical devices, aerospace, automobiles, and electronic products.