Stahldraht

Abstract

A steel wire is formed from a steel containing not less than 1.0 wt% and not more than 1.1 wt% C, not less than 0.15 wt% and not more than 0.25 wt% Si, not less than 0.25 wt% and not more than 0.35 wt% Mn, and not less than 0.15 wt% and not more than 0.25 wt% Cr, the remainder being Fe and unavoidable impurities. The steel wire 1 has a wire diameter D of at least 0.15 mm and at most 0.42 mm. The steel has a pearlitic structure. The steel has a dislocation density of not less than 2.4 × 10⁻⁶ 16 m -2 and no more than 5.0×10 16 m -2 The steel exhibits a circumferential full width of no less than 42° at the apex of the maximum intensity of a Debye ring for the Fe(211) plane.

Description

Technical area

[0001] The present invention relates to a steel wire.

[0002] This application claims priority based on Japanese Patent Application No. 2022-25608, filed on February 22, 2022, the entire contents of which are incorporated herein by reference. Background technology

[0003] A steel cord containing a pearlite structure can be used, for example, as a steel wire forming a steel rope. During the production of a steel cord, a plurality of steel wires are stranded together. Therefore, a steel wire used for such applications must exhibit not only tensile strength but also toughness to suppress wire breakage during stranding. A method for producing a steel wire that achieves both tensile strength and toughness has been proposed (see, for example, Japanese Patent Application Publication No. 2019-56162 (Patent Literature 1)). Citation listPatent literature

[0004] Patent Literature 1: Japanese Patent Application Publication No. 2019-56162 Summary of the invention

[0005] A steel wire according to the present invention is formed of a steel comprising: not less than 1.0 mass% and not more than 1.1 mass% of C (carbon), not less than 0.15 mass% and not more than 0.25 mass% of Si (silicon), not less than 0.25 mass% and not more than 0.35 mass% of Mn (manganese), and not less than 0.15 mass% and not more than 0.25 mass% of Cr (chromium), with the balance being Fe (iron) and unavoidable impurities. The steel wire of the present invention has a wire diameter of not less than 0.15 mm and not more than 0.42 mm. The steel has a pearlite structure.

[0006] The steel has a dislocation density of not less than 2.4×10 16 m -2 and not more than 5.0×10 16 m -2 The steel has a circumferential half-width of not less than 42° at the apex of maximum intensity of a Debye ring for the Fe(211) plane. Brief description of the drawings Fig. 1 is a schematic perspective view showing the structure of a steel wire. Fig. Figure 2 is a flowchart showing an overview of a process for manufacturing a steel wire. Fig. Figure 3 is a graph illustrating the relationship between dislocation density and tensile strength. Description of Embodiments [Problems to be Solved by the Present Invention]

[0007] As described above, there are cases where a steel wire must have both tensile strength and toughness. One of the objects of the present invention is to provide a steel wire that has both high tensile strength and high toughness. [Advantageous effects of the present invention]

[0008] With the steel wire of the present invention, both high tensile strength and high toughness can be achieved. [Description of the embodiments of the present invention]

[0009] The embodiments of the present invention will first be listed and described. A steel wire of the present invention is made of a steel containing not less than 1.0 mass % and not more than 1.1 mass % of C, not less than 0.15 mass % and not more than 0.25 mass % of Si, not less than 0.25 mass % and not more than 0.35 mass % of Mn, and not less than 0.15 mass % and not more than 0.25 mass % of Cr, with the balance being Fe and unavoidable impurities. The steel wire of the present invention has a wire diameter of not less than 0.15 mm and not more than 0.42 mm.

[0010] The steel has a pearlite structure. The steel has a dislocation density of no less than 2.4×10 16 m -2 and not more than 5.0×10 16 m -2 The steel has a circumferential half-width of not less than 42° at the apex of maximum intensity of a Debye ring for the Fe(211) plane.

[0011] Increasing the degree of deformation (reducing the area) in a wire drawing step during the production of a steel wire can increase the strength of the steel wire. However, this is accompanied by a decrease in the toughness of the steel wire.

[0012] According to studies conducted by the inventors, in the production of a steel wire formed from a steel with a pearlite structure, even in the case where the degree of processing in the wire drawing step is increased to increase the dislocation density and thereby enhance the tensile strength, high toughness can be ensured by suppressing the increase in crystal orientation in the steel constituting the steel wire. Specifically, in the steel wire of the present invention, the Debye ring for the Fe(211) plane of the steel constituting the steel wire has a high dislocation density value of 2.4×10 16 m -2 or more and 5.0×10 16 m -2or less, has a half-width in the circumferential direction of 42° or more at the apex of maximum intensity. Accordingly, the steel wire of the present invention can ensure excellent toughness despite the high tensile strength. Thus, the steel wire of the present invention can achieve both high tensile strength and high toughness.

[0013] As used herein, "wire diameter" means the diameter of a circle having the same area as the cross-section perpendicular to the longitudinal direction of the steel wire. The shape of the cross-section of the steel wire perpendicular to the longitudinal direction is not specifically limited and can take any shape. For example, the cross-section of the steel wire perpendicular to the longitudinal direction can be circular. In this case, "wire diameter" means the diameter of the cross-section perpendicular to the longitudinal direction of the steel wire.

[0014] For the above-mentioned steel wire, the half-width must be no less than 60° and no more than 90°. Setting the half-width to 60° or more makes it easier to ensure high toughness. Setting the half-width to 90° or less enables a high dislocation density and facilitates the achievement of high tensile strength.

[0015] For the above-mentioned steel wire, the dislocation density shall not be less than 3.0×10 16 m -2 and not more than 5.0×10 16 m -2 Setting the dislocation density to 3.0×10 16 m - 2 or more makes it easier to ensure high tensile strength. Setting the dislocation density to 5.0×10 16 m -2 or less facilitates ensuring high toughness by suppressing crystal orientation.

[0016] For the above-mentioned steel wire, the wire diameter can be not less than 0.15 mm and not more than 0.18 mm, and the tensile strength can be not less than 4240 MPa and not more than 4900 MPa.

[0017] For the above-mentioned steel wire, the wire diameter can be not less than 0.18 mm and not more than 0.21 mm, and the tensile strength can be not less than 4180 MPa and not more than 4740 MPa.

[0018] For the above-mentioned steel wire, the wire diameter can be not less than 0.21 mm and not more than 0.30 mm, and the tensile strength can be not less than 4000 MPa and not more than 4580 MPa.

[0019] With the above-mentioned combinations of wire diameter and tensile strength, sufficient tensile strength is achieved for any wire diameter. Tensile strength can be measured, for example, according to JIS (Japanese Industrial Standards) Z 2241.

[0020] The reasons for limiting the composition of the steel from which the steel wire is formed to the ranges described above are now described. C: not less than 1.0 mass% and not more than 1.1 mass%

[0021] C is an element that greatly influences the strength of pearlite steel wire. To achieve sufficient tensile strength of the steel wire, a C content of 1.0 mass% or more is required. A higher C content reduces toughness. To ensure sufficient toughness, a C content of 1.1 mass% or less is required. From the perspective of improving toughness, the C content is preferably 1.05 mass% or less. Si: not less than 0.15 mass% and not more than 0.25 mass%

[0022] Si is an element used as a deoxidizer in steel refining. Si also increases the strength of the ferrite in the pearlite structure. To ensure high tensile strength, a Si content of 0.15 mass% or more is required. A higher Si content can reduce toughness. To ensure sufficient toughness, a Si content of 0.25 mass% or less is required. Mn: not less than 0.25 mass% and not more than 0.35 mass%

[0023] Like Si, Mn is an element used as a deoxidizer in steel refining. To achieve sufficient deoxidizer effectiveness, the manganese content must be 0.25 mass% or more. If the amount of Mn added is large, a martensitic structure would likely form during cooling after heating during wire drawing. The resulting martensitic structure would impair the workability during wire drawing. Therefore, the Mn content must be 0.35 mass% or less. Cr: not less than 0.15 mass% and not more than 0.25 mass%.

[0024] Cr contributes to increasing the tensile strength of a steel wire. To ensure high tensile strength, a Cr content of 0.15 mass% or more is required. The addition of Cr increases raw material costs. To reduce raw material costs, a Cr content of 0.25 mass% or less is required. Inevitable contamination

[0025] During the production of steel wire, P (phosphorus), S (sulfur), and other unavoidable impurities mix into the steel from which the steel wire is formed. Excessive amounts of P and S lead to grain boundary segregation and the formation of inclusions, which degrades the properties of the steel. Therefore, the P and S content should preferably not exceed 0.025 mass% each. The total content of unavoidable impurities, including P and S, should preferably not exceed 0.3 mass%. [Details of embodiments of the present invention]

[0026] An embodiment of the steel wire according to the present invention will be described below with reference to the drawings. In the drawings to which reference is made below, like or corresponding parts are designated by the same reference numerals, and the description thereof will not be repeated.

[0027] Fig. Figure 1 is a schematic perspective view showing the structure of a steel wire. In Fig. 1 also shows a cross-section of the steel wire perpendicular to the longitudinal direction. With respect to Fig.1, the steel wire 1 in the present embodiment is a steel wire with a circular cross-section perpendicular to the longitudinal direction and an outer peripheral surface 11 with a cylindrical surface shape. The steel wire 1 has a wire diameter D of at least 0.15 mm and at most 0.42 mm. The cross-section of the steel wire 1 perpendicular to the longitudinal direction may be non-circular, e.g., elliptical.

[0028] The steel wire 1 is formed from a steel containing not less than 1.0 mass% and not more than 1.1 mass% of C, not less than 0.15 mass% and not more than 0.25 mass% of Si, not less than 0.25 mass% and not more than 0.35 mass% of Mn, and not less than 0.15 mass% and not more than 0.25 mass% of Cr, with the remainder being Fe and unavoidable impurities. The steel from which the steel wire 1 is formed has a pearlite structure. The steel from which the steel wire 1 is formed has a dislocation density of not less than 2.4×10 16 m -2 and not more than 5.0×10 16 m -2 The steel from which the steel wire 1 is formed has a half-width in the circumferential direction of not less than 42° at the apex of the maximum intensity of a Debye ring for the Fe (211) plane.

[0029] The dislocation density of the steel from which steel wire 1 is formed can be measured, for example, using a synchrotron X-ray diffractometer (XRD). The full width at half maximum in the circumferential direction at the apex of maximum density of the Debye ring for the Fe(211) plane of the steel forming steel wire 1 can be obtained, for example, by measuring the entire circumference of the Debye ring for the Fe(211) plane in two dimensions with XRD and calculating the full width at half maximum in the circumferential direction at the apex of maximum intensity.

[0030] An example of the method for producing the steel wire 1 will now be described. With reference to Fig.2, in the method for manufacturing the steel wire 1 in the present embodiment, a raw material preparation step is first performed as step S10. In step S10, a raw material wire formed of a steel containing not less than 1.0 mass% and not more than 1.1 mass% of C, not less than 0.15 mass% and not more than 0.25 mass% of Si, not less than 0.25 mass% and not more than 0.35 mass% of Mn, and not less than 0.15 mass% and not more than 0.25 mass% of Cr, with the balance being Fe and unavoidable impurities, is manufactured. The raw material wire may have a wire diameter of, for example, not less than 4 mm and not more than 6 mm.

[0031] Next, a first wire drawing step is performed as step S20. In step S20, the raw wire prepared in step S10 is subjected to a drawing process. In the present embodiment, the drawing is performed such that the raw wire in step S20 has a wire diameter of, for example, not less than 1 mm and not more than 2 mm.

[0032] Next, a patenting step is performed as step S30. In this step S30, the raw material wire drawn in step S20 is subjected to patenting. Specifically, the raw material wire is first heated to a temperature range not lower than the temperature at which the steel from which the wire is formed is austenitized (temperature range of the Acm point or higher), which is, for example, a temperature range of not less than 950°C and not higher than 1000°C, and held for a period of not less than five seconds and not longer than ten seconds (austenitizing treatment). Thereafter, the raw material wire is rapidly cooled to a temperature range higher than the temperature at which the martensitic transformation of the steel begins (temperature range of the MS point or higher), for example,a temperature range of not less than 500°C and not more than 600°C, and maintained within this temperature range (isothermal transformation treatment). This transforms the metallographic structure of the raw wire material into a fine pearlite structure. During the above austenitizing treatment, the raw wire material can be heated in an inert gas atmosphere to suppress the occurrence of decarburization.

[0033] Next, an orientation reduction step is performed as step S40. In this step S40, the raw wire drawn in step S20 and patented in step S30 is subjected to a heat treatment. Specifically, in step S40, a heat treatment is performed in which the raw wire is heated to a temperature range of not less than 600°C and not more than 665°C and held for a period of not less than five seconds and not more than ten seconds. This heat treatment reduces the orientation of the steel.

[0034] Next, a second wire drawing step is performed as step S50. In this step S50, the raw material wire that was patented in step S30 and subjected to orientation reduction in step S40 is subjected to a drawing process. In the present embodiment, the drawing is performed so that the raw material wire acquires a wire diameter of not less than 0.15 mm and not more than 0.42 mm in step S50. The steel wire of the present embodiment is completed through the above steps.

[0035] In the steel wire manufacturing method of the present embodiment, the heat treatment is performed in step S40 to reduce the orientation of the steel. In this step S40, an appropriate temperature and holding time are selected to suppress the decrease in the dislocation density while simultaneously reducing the orientation of the steel. With the wire drawing performed in step S50, the dislocation density increases, and high tensile strength is achieved. At this time, although the orientation of the steel is increased by the wire drawing in step S50, the orientation has been reduced in step S40, so that the orientation of the steel becomes narrower than in the case where step S40 is not performed. As a result, it is possible to achieve a half-width in the circumferential direction of 42° or more at the apex of the maximum intensity of the Debye ring for the Fe(211) plane while maintaining a dislocation density of 2.4×10 16 m-2 or more and 5.0×10 16 m -2 or less is achieved.

[0036] In the steel wire 1 of the present embodiment, the Debye ring for the Fe(211) plane of the steel from which the steel wire is formed has a high dislocation density value of 2.4×10 10 m -2 or more and 5.0×10 16 m -2 or less, the half-width in the circumferential direction is 42° or more at the peak of maximum intensity. This makes the steel wire 1 a steel wire that has both high tensile strength and high toughness. Due to the high toughness, the steel wire 1 can suppress wire breakage during the stranding process. Therefore, the steel wire 1 is suitable as a steel wire that forms a high-strength steel cord.

[0037] In the present embodiment, the half-width is preferably not less than 60° and not more than 90°. Setting the half-width to 60° or more makes it easier to ensure high toughness. Setting the half-width to 90° or less enables a high dislocation density and facilitates the achievement of high tensile strength.

[0038] In the present embodiment, the dislocation density is preferably not less than 3.0×10 16 m -2 and not more than 5.0×10 16 m -2 . If the dislocation density is set to 3.0×10 10 m -2 or more, it is easier to ensure high tensile strength. Setting the dislocation density to 5.0×10 16 m -2 or less facilitates ensuring high toughness by suppressing crystal orientation.

[0039] In the present embodiment, the wire diameter D can be not less than 0.15 mm and not more than 0.18 mm, and the tensile strength can be not less than 4240 MPa and not more than 4900 MPa. The wire diameter D can be not less than 0.18 mm and not more than 0.21 mm, and the tensile strength can be not less than 4180 MPa and not more than 4740 MPa. The wire diameter D can be not less than 0.21 mm and not more than 0.30 mm, and the tensile strength can be not less than 4000 MPa and not more than 4580 MPa. With the above combinations of wire diameter D and tensile strength, sufficient tensile strength is achieved for any wire diameter D. EXAMPLES

[0040] Experiments were conducted to confirm that the steel wire 1 of the present invention can achieve both high tensile strength and high toughness. The experimental procedures were as follows. (1) Relationship between dislocation density and tensile strength

[0041] Two types of raw material wires (raw material wires A and B) made of steel with different C contents were prepared, and the steel wires were manufactured using the same method as in the above embodiment. The component compositions of steel from which the raw material wires are formed are listed in Table 1. Raw material wires with a circular cross-section and wire diameters of 4.0 mm and 5.5 mm were prepared, which were drawn to wire diameters of 1.3 mm and 1.5 mm in the first wire drawing step. Subsequently, the wires were heated to 980°C and held for eight seconds, and then rapidly cooled to 580°C for patenting. Subsequently, the wires were subjected to a heat treatment in which they were heated to 640°C and held for eight seconds to reduce their orientation.The wires were then copper-plated and galvanized, and then copper and zinc diffused into each other to form a brass layer with a thickness of 2 μm. The wires were then drawn in the second wire drawing step to obtain steel wires (element wires) with a wire diameter of 0.21 mm. The area reductions at this time were 97% and 98%. Steel wires with different dislocation densities were obtained due to different area reductions. The area reduction r is defined by the following expression (1), where S0 is the cross-sectional area before drawing and S1 is the cross-sectional area after drawing in the cross section perpendicular to the longitudinal direction of a wire (steel wire). r={(S0−S1) / S0}×100(%) [Table 1] C Si Mn Cr Fe A 1.05 0.20 0.30 0.20 rest B 0.90 0.25 0.35 0.20 rest

[0042] For the steel wires thus obtained, the dislocation density was measured and the tensile strength was examined. The dislocation density was measured in the following way. First, approximately 20 steel wires prepared in the manner described above were arranged side by side to form a sample to increase the X-ray radiation area, and this sample was irradiated with X-rays. Then, line profiles of the diffraction peaks for the (110) plane, the (200) plane, the (211) plane, the (220) plane, and the (310) plane of iron were obtained. These line profiles were analyzed using the modified Williamson-Hall method and the modified Warren-Averbach method to calculate the dislocation density. The modified Williamson-Hall method and the modified Warren-Averbach method are well-known methods, the details of which can be found, for example, in T. Ungar and A.Borbely, “The effect of dislocation contrast on x-ray line broadening: A new approach to line profile analysis”, Appl. Phys. Lett., vol. 69, no. 21, p. 3173, 1996, and in T. Ungar, S. Ott, P. Sanders, A. Borbely, J. Weertman, “Dislocations, grain size and planar faults in nanostructured copper determined by high resolution X-ray diffraction and a new procedure of peak profile analysis”, Acta Mater., vol. 46, no. 10, pp. 3693-3699, 1998. Synchrotron radiation was used as the X-ray source. A planar Si(111) double crystal monochromator and a Pt (platinum) coated mirror were used. The angle of incidence of the X-rays was 2.5 mrad, and the wavelength was 0.0689 nm (energy: 18.0 keV). A NaI scintillation counter was used as the detector. 2θ-θscan was used as the scanning method.The entrance slit had a width of 4 mm and a height of 0.5 mm, and the light receiving slit was a double slit (with a width of 4 mm and a height of 0.5 mm). The measurement conditions were set so that there were nine or more measurement points within the full width at half maximum of each diffraction peak, the peak intensity was 2000 counts or more, and the measurement range was approximately ten times the full width at half maximum.

[0043] The tensile test was conducted in accordance with JIS Z 2241. The relationship between dislocation density and tensile strength obtained from the experiments is shown in Fig. 3 shown.

[0044] In Fig.3. The horizontal axis corresponds to dislocation density. The vertical axis corresponds to tensile strength. The solid circles are data points for the steel wires made from raw material wire A. The hollow circles are data points for the steel wires made from raw material wire B. The solid and dashed lines show the relationship between dislocation density and tensile strength in raw material wires A and B, respectively.

[0045] Out of Fig. Figure 3 shows that the tensile strength increases with increasing dislocation density. It can be seen that a high tensile strength of 4000 MPa or more can be achieved when a raw material wire with a carbon content of 1.0 mass% or more is used and the dislocation density is increased to 2.4×10 16 m -2 or more is set. (2) Relationship between half-width and toughness

[0046] Steel wires were manufactured using the raw material Wire A by the same method as in (1) above. This time, Sample 1 was prepared with a heating temperature of 665°C and a holding time of 10 seconds in step S40, Sample 2 was prepared with a heating temperature of 600°C and a holding time of 5 seconds. Sample 3 was prepared by omitting step S40. Sample 4 was also prepared by setting the area reduction in the first wire drawing step smaller than that of Samples 1 to 3 and omitting step S40. For each sample, the full width at half maximum was measured and the toughness was evaluated.

[0047] The full width at half maximum was measured using an X-ray residual stress analyzer (model number: µ-X360s) from Pulstec Industrial Co., Ltd. Using a Cr tube as the X-ray source, the full width at half maximum in the circumferential direction was calculated at the apex of maximum intensity of a Debye ring for the Fe(211) plane under the condition that the longitudinal direction of the steel wire was aligned with the incident direction and the angle between the surface of the steel wire and the X-ray incident direction was 35 degrees (incident angle: 35 degrees). Specifically, the full width at half maximum was calculated according to the following method. First, a point corresponding to a maximum intensity peak was identified for the Debye ring for the Fe(211) plane obtained under the above conditions.Subsequently, the peak intensities were examined in the circumferential direction for a circle passing through this point and concentric with the Debye ring. The angle between two points corresponding to half the intensity of the peak with maximum intensity was then calculated as the half-width angle. To evaluate toughness, four brass-coated steel wires with a wire diameter of 0.30 mm were bundled and stranded together using a bundle stranding machine under the same conditions. The number of wire breaks per ton of steel wire was measured. The test results are presented in Table 2. [Table 2] Half-width (°) Number of wire breaks (times / t) Assessment of toughness Dislocation density (×10 16 / m -2 ) 1 72 4 A 4.1 2 43 15 B 4.3 3 35 >30 C 3.8 4 82 3 A 1.9

[0048] For the toughness evaluation in Table 2, considering the yield in mass production of steel cords, A was assigned to those with a favorable number of steel wire breaks, B to those with an acceptable number, and C to those for which improvement was desired. It should be noted that, as shown in Table 2, samples 1 to 3 each had a dislocation density of 3.8×10 16 m -2 up to 4.3×10 16 m -2 have.

[0049] Referring to Table 2, it can be seen that despite similar dislocation densities, there are differences in the number of wire breaks in Samples 1 to 3. This is due to the differences in the circumferential half-width at the apex of the maximum intensity of the Debye ring for the Fe(211) plane. It is confirmed that high toughness can be achieved in Samples 1 and 2 with a half-width of 42° or more. It is also confirmed that even higher toughness can be achieved in Sample 1 with a half-width of 60° or more. On the other hand, although the half-width can be slightly increased by reducing the area reduction in the first wire drawing step, this results in a reduction in the dislocation density to 1.9×10 16 m -2 as in Sample 4. As a result, it is difficult to achieve a high tensile strength of, for example, 4000 MPa or more, as in Fig. 3 shown.

[0050] As described above, the steel wire of the present invention is capable of achieving both high tensile strength and high toughness, making it suitable for, for example, a steel wire forming a steel cord. The application of the steel wire of the present invention is not limited to steel cords; it is applicable to ropes for conveyors and handrails, as well as wires for rubber reinforcement.

[0051] It should be understood that the embodiments and examples disclosed herein are in all respects illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims rather than by the above description, and is intended to include all changes within the scope and meaning that comply with the terms of the claims. List of reference symbols

[0052] 1: steel wire; 11: outer peripheral surface; D: wire diameter; and S10, S20, S30, S40, S50: step. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2022-25608

[0002] JP 2019-56162

[0003] Cited non-patent literature

[0000] T. Ungar and A. Borbely, “The effect of dislocation contrast on x-ray line broadening: A new approach to line profile analysis,” Appl. Phys. Lett., vol. 69, no. 21, p. 3173, 1996

[0042] T. Ungar, S. Ott, P. Sanders, A. Borbely, J. Weertman, „Dislocations, grain size and planar faults in nanostructured copper determined by high resolution X-ray diffraction and a new procedure of peak profile analysis“, Acta Mater., vol. 46, no. 10, pp. 3693-3699, 1998

[0042]

Claims

[1] Steel wire formed from a steel comprising: not less than 1.0 mass% and not more than 1.1 mass% C, not less than 0.15 mass% and not more than 0.25 mass% Si, at least 0.25 mass% and at most 0.35 mass% Mn, and at least 0.15 mass% and at most 0.25 mass% Cr, the remainder being Fe and unavoidable impurities; wherein the steel wire has a wire diameter of not less than 0.15 mm and not more than 0.42 mm, where the steel has: a pearlite structure, a dislocation density of not less than 2.4×10 16 m -2 and not more than 5.0×10 16 m -2 , and a half-width in a circumferential direction of not less than 42° at a vertex of maximum intensity of a Debye ring for the Fe(211) plane. [2] Steel wire according to claim 1, wherein the half width is not less than 60° and not more than 90°. [3] Steel wire according to claim 1 or 2, wherein the dislocation density is not less than 3.0×10 16 m -2 and not more than 5.0×10 16 m -2 amounts. [4] Steel wire according to one of claims 1 to 3, wherein the wire diameter is not less than 0.15 mm and not more than 0.18 mm, and the steel wire has a tensile strength of not less than 4240 MPa and not more than 4900 MPa. [5] Steel wire according to one of claims 1 to 3, wherein the wire diameter is not less than 0.18 mm and not more than 0.21 mm, and the steel wire has a tensile strength of not less than 4180 MPa and not more than 4740 MPa. [6] Steel wire according to one of claims 1 to 3, wherein the wire diameter is not less than 0.21 mm and not more than 0.30 mm, and the steel wire has a tensile strength of not less than 4000 MPa and not more than 4580 MPa.

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