Magnetic wire, composite magnetic wire, and method for producing magnetic wire

Abstract

Provided is a magnetic wire made of an alloy containing iron and cobalt as main components, wherein the alloy contains 6.5-10.5 mass% of vanadium and 0.3-1.2 mass% of manganese, a cross section of the magnetic wire has an interior and an exterior, the interior is a region where the proportion of the magnetic wire in which the crystal orientation in the longitudinal direction of the magnetic wire is the normal direction of the (113) plane is less than 17%, the exterior is a region where the proportion of the magnetic wire in which the crystal orientation in the longitudinal direction of the magnetic wire is the normal direction of the (113) plane is 17% or more, and the Vickers hardness is 450-530 HV.

Description

Magnetic wire, composite magnetic wire, and method for manufacturing magnetic wire

[0001] This disclosure relates to magnetic wires, composite magnetic wires, and methods for manufacturing magnetic wires. This application claims priority under the International Application No. PCT / JP2025 / 015235 dated 18 April 2025, which incorporates all the provisions of the said International Application by reference.

[0002] Patent Document 1 discloses a magnetic wire made of an alloy mainly composed of iron and cobalt. This magnetic wire contains at least an α phase and has a structure in which the area ratio of the α phase, the average grain size of the α phase, and the ratio of the length of the high-angle grain boundaries satisfy a specific range. This magnetic wire is manufactured by twisting a wire having a specific structure in which the α phase and γ phase coexist.

[0003] International Publication No. 2023 / 074693

[0004] The magnetic wire of this disclosure is made of an alloy mainly composed of iron and cobalt. The alloy contains 6.5% to 10.5% by mass of vanadium and 0.3% to 1.2% by mass of manganese. The cross-section of the magnetic wire has an interior and an exterior. The interior is a region in which the proportion of the crystal orientation in the longitudinal direction of the magnetic wire being normal to the (113) plane is less than 17%. The exterior is a region in which the proportion of the crystal orientation in the longitudinal direction of the magnetic wire being normal to the (113) plane is 17% or more. The Vickers hardness is 450 HV to 530 HV.

[0005] Figure 1 is a schematic perspective view of the magnetic wire of the embodiment. Figure 2 is a cross-sectional view taken along line II-II in Figure 1. Figure 3 is a diagram showing an example of an EBSD-IPF map in the cross-section of the magnetic wire of the embodiment. Figure 4 is an enlarged view of region IV in Figure 3. Figure 5 is an enlarged view of region V in Figure 3. Figure 6 is an enlarged view of region VI in Figure 3. Figure 7 is a schematic diagram showing the twist marks of the magnetic wire of the embodiment. Figure 8 is a schematic diagram illustrating the manufacturing method of the magnetic wire of the embodiment. Figure 9 is a schematic perspective view of the composite magnetic wire of the embodiment. Figure 10 is a table showing a list of the composition of the samples in the test example. Figure 11 is a table showing the conditions for each sample in the test example. Figure 12 is a table showing the results for each sample in the test example.

[0006] Further increases in the power output of magnetic wires that generate the large Barkhausen jump phenomenon are needed. Magnetic wires are used in magnetic sensors. A magnetic sensor comprises a core made of magnetic wire and a coil wound around the outer circumference of this core. The performance of a magnetic sensor largely depends on the characteristics of the magnetic wire used in the core. To miniaturize and increase the power output of magnetic sensors, magnetic wires that can produce high output are desired.

[0007] One of the objectives of this disclosure is to provide a magnetic wire with excellent output characteristics. Another objective of this disclosure is to provide a composite magnetic wire with excellent output characteristics. Another objective of this disclosure is to provide a method for manufacturing a magnetic wire that can produce a magnetic wire with excellent output characteristics.

[0008] The magnetic wires of this disclosure exhibit excellent output characteristics.

[0009] First, the embodiments of this disclosure will be listed and described.

[0010] (1) The magnetic wire according to the embodiment of the present disclosure is made of an alloy mainly composed of iron and cobalt. The alloy contains 6.5% by mass or more and 10.5% by mass or less of vanadium and 0.3% by mass or more and 1.2% by mass or less of manganese. The cross-section of the magnetic wire has an interior and an exterior. The interior is a region in which the proportion of the crystal orientation in the longitudinal direction of the magnetic wire being normal to the (113) plane is less than 17%. The exterior is a region in which the proportion of the crystal orientation in the longitudinal direction of the magnetic wire being normal to the (113) plane is 17% or more. The Vickers hardness is 450 HV or more and 530 HV or less.

[0011] The proportion of the cross-section of a magnetic wire in which the longitudinal crystal orientation of the magnetic wire is normal to the (113) plane can be determined by crystallographic analysis using the EBSD (Electron Back Scattered Diffraction Pattern) method. Hereinafter, the proportion of the cross-section of a magnetic wire in which the longitudinal crystal orientation of the magnetic wire is normal to the (113) plane may be referred to as the (113) plane orientation ratio. The longitudinal direction of a magnetic wire is the direction from the first end to the second end of the magnetic wire along its axis. If the orientation ratio of the internal (113) planes in the cross-section of a magnetic wire is less than 17% and the orientation ratio of the external (113) planes is 17% or more, the output characteristics are high, as shown in the test examples described later.

[0012] As described later, magnetic wires are manufactured by drawing and heat-treating a wire material, and then applying torsional stress to the heat-treated material while heating it with an electric current. If the Vickers hardness of the magnetic wire is within the above range, tensile residual stress is easily introduced into the magnetic wire through the twisting process during the manufacturing process, which tends to result in higher output characteristics. In other words, magnetic wires with a Vickers hardness within the above range have high output characteristics.

[0013] Since the above-mentioned magnetic wire has high output characteristics, using this magnetic wire as the core of the magnetic sensor described above can increase the output power of the magnetic sensor. In addition to having high output characteristics, the above-mentioned magnetic wire has low output variation. With a magnetic wire that has low output variation, it is easy to obtain a stable output even when miniaturizing by reducing the diameter or length of the magnetic wire. Therefore, using this magnetic wire as the core of the magnetic sensor described above can miniaturize the magnetic sensor.

[0014] (2) In the magnetic wire described in (1) above, the alloy may contain more than 0.0% by mass and up to 0.4% by mass of silicon.

[0015] Magnetic wires made from alloys containing silicon within the above range tend to have high output characteristics.

[0016] (3) In the magnetic wire of (1) or (2) above, the alloy may contain 0.2% by mass or more and 0.8% by mass or less of aluminum.

[0017] Magnetic wires made from alloys containing aluminum within the above range tend to have high output characteristics.

[0018] (4) In the magnetic wire described in (3) above, the alloy may contain 0.02% by mass or more and 0.15% by mass or less of titanium.

[0019] Magnetic wires made from aluminum-containing alloys may have reduced machinability. Adding titanium tends to improve machinability. Magnetic wires made from alloys containing both aluminum and titanium tend to have improved output characteristics and machinability.

[0020] (5) Any of the magnetic wires described in (1) to (4) above may have a weight ratio of cobalt to iron, Co / Fe, of 1.20 or more and 1.45 or less.

[0021] Magnetic wires with a Co / Fe ratio within the above range tend to have high output characteristics.

[0022] (6) Any of the magnetic wires described in (1) to (5) above may have a twist mark on its outer surface, and the angle of the twist mark with respect to the axis of the magnetic wire may be 2° or more and 60° or less.

[0023] Magnetic wires with twist marks tend to retain the tensile residual stress introduced into the wire by the twisting process. When the angle of the twist mark is within the above range, the tensile residual stress is more easily introduced uniformly along the longitudinal direction of the magnetic wire over its entire length. As a result, the output characteristics of the magnetic wire tend to be higher.

[0024] (7) In any of the magnetic wires described in (1) to (6) above, the diameter of the magnetic wire may be 0.1 mm or more and 1.0 mm or less, and the length of the magnetic wire may be 25 mm or less.

[0025] Generally, if the diameter of a magnetic wire is small or the length of the magnetic wire is short, the volume of the magnetic wire decreases, which tends to lower the output of the magnetic wire. Also, if the length of the magnetic wire is short, the effect of the demagnetizing field becomes larger, so the output of the magnetic wire tends to fluctuate. A magnetic wire in which the orientation ratio of (113) planes in the cross-section satisfies specific conditions and the Vickers hardness satisfies a specific range, as described above, can obtain high output and low output fluctuation. Therefore, even if the diameter of the magnetic wire is small or the length is short, a stable output can be easily obtained. A magnetic wire in which the orientation ratio of (113) planes in the cross-section satisfies specific conditions and the Vickers hardness satisfies a specific range has sufficient output characteristics even if the diameter is small or the length is short. When a magnetic wire with diameter and length within the above ranges is used as the core of a magnetic sensor, the magnetic sensor can be miniaturized.

[0026] (8) A composite magnetic wire according to an embodiment of the present disclosure comprises any of the magnetic wires described in (1) to (7) above, and a metallic coating material disposed on the outer surface of the magnetic wire.

[0027] Composite magnetic wires are manufactured, for example, by drawing and heat-treating a coated wire in which a metal coating material is placed on the outer surface of the wire that will be used as the material for the magnetic wire, and then applying torsional stress to the heat-treated material while heating it with electricity. When a metal coating material is placed on the outer surface of the magnetic wire, residual tensile stress is easily introduced into the magnetic wire by the torsional process during the manufacturing of composite magnetic wires, which tends to improve the output characteristics of the magnetic wire.

[0028] (9) In the composite magnetic wire described in (8) above, the ratio of the diameter of the magnetic wire to the diameter of the composite magnetic wire may be 45% or more and 95% or less.

[0029] If the ratio of the diameter of the magnetic wire to the diameter of the composite magnetic wire is 45% or more, the ratio of the cross-sectional area of the magnetic wire to the cross-sectional area of the composite magnetic wire will not be excessively small, and the output characteristics of the composite magnetic wire tend to be high. If the ratio of the diameter of the magnetic wire to the diameter of the composite magnetic wire is 95% or less, the ratio of the cross-sectional area of the coating material to the cross-sectional area of the composite magnetic wire will not be excessively small, and in the manufacturing process of the composite magnetic wire, tensile residual stress is easily introduced into the magnetic wire by twisting, and the output characteristics of the magnetic wire tend to be high.

[0030] (10) In the composite magnetic wire according to the above (8) or the above (9), the melting point of the coating material may be more than 850°C.

[0031] If the melting point of the coating material is more than 850°C, heat treatment can be performed in the manufacturing process of the composite magnetic wire.

[0032] (11) In the composite magnetic wire according to any one of the above (8) to (10), the Vickers hardness of the coating material may be 200 HV or more.

[0033] If the Vickers hardness of the coating material is 200 HV or more, tensile residual stress is easily introduced into the magnetic wire by twisting in the manufacturing process of the composite magnetic wire, and the output characteristics of the magnetic wire tend to be high.

[0034] (12) A method for manufacturing a magnetic wire according to an embodiment of the present disclosure includes a step of subjecting a material made of an alloy containing iron and cobalt as main components to drawing to produce a drawn wire, a step of subjecting the drawn wire to heat treatment to produce a heat-treated material, and a step of performing current heating while applying twisting stress to the heat-treated material to produce a magnetic wire. The alloy contains 6.5 mass% or more and 10.5 mass% or less of vanadium, and 0.3 mass% or more and 1.2 mass% or less of manganese. The current heating is performed at 18.0 A / mm ２ exceeding and 22.0 A / mm ２ or less of current density for a predetermined time.

[0035] With the above-described method for producing a magnetic wire, after wire drawing and heat treatment are performed on a wire rod serving as the material of the magnetic wire, electric current heating is performed while applying torsional stress to the heat-treated material, whereby a magnetic wire with excellent output characteristics can be produced. When electric current heating is performed while applying torsional stress, in the cross section of the magnetic wire, a structure in which the orientation ratio of the (113) plane in the inner portion is less than 17% and the orientation ratio of the (113) plane in the outer portion is 17% or more is easily formed. Further, when electric current heating is performed while applying torsional stress, the Vickers hardness tends to be 450 HV or more and 530 HV or less. When the orientation ratio of the (113) plane in the cross section satisfies the specific condition and the Vickers hardness falls within the specific range, the output characteristics of the magnetic wire are enhanced.

[0036] Specific examples of the magnetic wire, the composite magnetic wire, and the method for producing a magnetic wire according to the present disclosure will be described with reference to the drawings. The same reference numerals in the drawings denote the same or corresponding parts. In each drawing, for the convenience of description, a part of the configuration may be exaggerated or simplified. The dimensional ratio of each part in the drawings may also differ from the actual one. The present invention is not limited to these exemplifications, is indicated by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims. It should be understood that at least one of the configurations and features described in each embodiment and example may be combined with other embodiments and examples, or may be modified in various ways.

[0037] <Magnetic Wire> The magnetic wire 1 of the embodiment will be described with reference to FIGS. 1 to 7. The magnetic wire 1 generates a large Barkhausen jump phenomenon when an external magnetic field is applied. The magnetic wire 1 is made of an alloy containing iron and cobalt as main components. One of the features of the magnetic wire 1 of the embodiment is that it satisfies the following three conditions (A), (B), and (C). (A) The alloy forming the magnetic wire 1 contains a specific composition. (B) The orientation ratio of the (113) plane in the cross section 10 of the magnetic wire 1 satisfies a specific condition. (C) The Vickers hardness falls within a specific range.

[0038] ≪Composition≫ The composition of the alloy forming the magnetic wire 1 mainly consists of iron (Fe) and cobalt (Co). "Mainly consisting of iron and cobalt" means that the total amount of iron and cobalt is 75% by mass or more. The composition of the magnetic wire 1 may also contain 80% by mass or 85% by mass or more of iron and cobalt in total. The content ratio of each element in the composition is the mass ratio of each element when the composition of the alloy is taken as 100% by mass. The melting point of the alloy forming the magnetic wire 1 is, for example, about 1300°C.

[0039] The weight ratio of cobalt to iron, Co / Fe, is, for example, 1.20 to 1.45. Magnetic wires 1 whose Co / Fe satisfies the above range tend to have high output characteristics. The weight ratio of cobalt to iron, Co / Fe, may also be 1.23 to 1.41, or 1.27 to 1.37. The cobalt content is, for example, 42.0% to 63.0%, 45.0% to 55.0%, or 48.0% to 53.0%. The iron content is, for example, 28.0% to 52.5%, 31.0% to 46.0%, or 33.0% to 44.0%.

[0040] The composition of the alloy forming magnetic wire 1 includes additive elements, with the remainder being iron, cobalt, and unavoidable impurities.

[0041] The composition of the alloy forming the magnetic wire 1 includes vanadium (V) and manganese (Mn) as additive elements other than iron and cobalt. The composition of the alloy forming the magnetic wire 1 may further include at least one of silicon (Si) and aluminum (Al) as additive elements. If the composition of the alloy forming the magnetic wire 1 includes aluminum as an additive element, it may further include titanium (Ti).

[0042] Vanadium contributes to improved magnetic properties and processability. The vanadium content is 6.5% by mass or more and 10.5% by mass or less. If the vanadium content is within the above range, the magnetic properties of the magnetic wire 1 can be improved. If the vanadium content is 6.5% by mass or more, in addition to improving magnetic properties, the processability during manufacturing of the magnetic wire 1 can be improved. The vanadium content may also be 7.5% by mass or more and 10.0% by mass or less, or 8.5% by mass or more and 9.5% by mass or less.

[0043] Manganese contributes to improved magnetic properties and processability. The manganese content is between 0.3% by mass and 1.2% by mass. If the manganese content is within the above range, the magnetic properties of the magnetic wire 1 can be improved. If the manganese content is 0.3% by mass or more, in addition to improving magnetic properties, the processability during manufacturing of the magnetic wire 1 can be improved. The manganese content may also be between 0.4% by mass and 1.0% by mass, or between 0.5% by mass and 0.8% by mass.

[0044] Silicon contributes to improving magnetic properties. The silicon content is greater than 0.0 mass% and less than or equal to 0.4 mass%. If the silicon content is within the above range, the magnetic properties of the magnetic wire 1 can be improved. If the silicon content is too high, the processability during manufacturing of the magnetic wire 1 may decrease. If the silicon content is 0.4 mass% or less, the processability during manufacturing of the magnetic wire 1 is unlikely to decrease. The silicon content may also be between 0.05 mass% and 0.38 mass%, or between 0.10 mass% and 0.35 mass%.

[0045] Aluminum contributes to improving magnetic properties. The aluminum content is between 0.2% by mass and 0.8% by mass. If the aluminum content is within the above range, the magnetic properties of the magnetic wire 1 can be improved. If the aluminum content is too high, the processability during manufacturing of the magnetic wire 1 may decrease. If the aluminum content is 0.8% by mass or less, the processability during manufacturing of the magnetic wire 1 is unlikely to decrease. The aluminum content may also be between 0.3% by mass and 0.7% by mass, or between 0.4% by mass and 0.65% by mass.

[0046] Titanium contributes to improved workability. If the alloy forming the magnetic wire 1 contains aluminum, workability may decrease. If the alloy forming the magnetic wire 1 contains aluminum, adding titanium further tends to improve workability. The titanium content is 0.02% by mass or more and 0.15% by mass or less. If the titanium content is within the above range, the workability during the manufacture of the magnetic wire 1 is unlikely to decrease. If the titanium content is too high, the magnetic properties may decrease. If the titanium content is 0.15% by mass or less, the magnetic properties are unlikely to decrease. The titanium content may also be 0.05% by mass or more and 0.13% by mass or less, or 0.08% by mass or more and 0.12% by mass or less.

[0047] The composition of the alloy forming the magnetic wire 1 may further include, in addition to the above-mentioned elements, one or more elements selected from the group consisting of nickel (Ni), chromium (Cr), molybdenum (Mo), niobium (Nb), tungsten (W), and copper (Cu) as additive elements. These elements have the effect of improving the output characteristics of the magnetic wire 1. The content ratio of each of these elements is, for example, greater than 0 mass% and 1.0 mass% or less, or 0.1 mass% to 0.8 mass%.

[0048] The composition of magnetic wire 1 can be determined, for example, by ICP emission spectroscopy (Inductively Coupled Plasma Optical Emission Spectrometer) or EDX (Energy Dispersive X-ray Spectroscopy).

[0049] <<Structure>> The magnetic wire 1 has a cross-section 10 as shown in Figure 2. The cross-section 10 is a cross-section obtained by cutting the magnetic wire 1 in a direction perpendicular to the longitudinal direction of the magnetic wire 1. The cross-section 10 has an interior 11 and an exterior 12. The interior 11 is a region in which the proportion of the crystal orientation of the magnetic wire 1 in the longitudinal direction being normal to the (113) plane is less than 17%. The exterior 12 is a region in which the proportion of the crystal orientation of the magnetic wire 1 in the longitudinal direction being normal to the (113) plane is 17% or more. The cross-section 10 has a structure in which the proportion of (113) plane orientation in the interior 11 is relatively low, and the proportion of (113) plane orientation in the exterior 12 is relatively high. The direction in which the (113) plane faces is perpendicular to the (113) plane.

[0050] The interior 11 is, for example, the region including the center 111 of the magnetic wire 1. The exterior 12 is, for example, the region including the outer edge 112 of the magnetic wire 1. In Figure 2, for clarity, the interior 11 is shown as a circle including the center 111 of the magnetic wire 1, and the exterior 12 is shown as an annular shape surrounding the interior 11. In Figure 2, for clarity, the boundary between the interior 11 and the exterior 12 is shown as a dashed line.

[0051] Here, in the orientation ratio of the (113) plane, the crystal orientation in the longitudinal direction of the magnetic wire 1 is defined as satisfying the condition that the angular difference between the crystal orientation and a line parallel to the axis of the magnetic wire 1 is within 10°. The proportion of the crystal orientation in the longitudinal direction of the magnetic wire 1 being normal to the (113) plane is the proportion of the area where the minimum angle among the angles of the (113) plane and the plane equivalent to the (113) plane with respect to a line parallel to the axis of the magnetic wire 1 is within 10°. The proportion of the area where the above angle is within 10° is calculated using the crystal lattice planes of an indexed body-centered cubic lattice.

[0052] As will be explained in the example described later, the orientation ratio of the (113) planes of the interior 11, as determined by crystal analysis using the EBSD method, may be 16% or less, 15% or less, or 14% or less. The interior 11 has a structure in which, for example, the orientation ratio of the (113) planes gradually increases from the center 111 toward the outside 12.

[0053] As explained in the example below, the orientation ratio of the (113) planes of the outer 12 obtained by crystal analysis using the EBSD method may be 18% or more, 19% or more, or 19.5% or more. The orientation ratio of the (113) planes of the outer 12 may be, for example, 35% or less, 30% or less, or 25% or less. The orientation ratio of the (113) planes of the outer 12 may also be 17% to 35%, 18% to 30%, 19% to 30%, or 19.5% to 25%.

[0054] The cross-section 10 has a structure in which, for example, the orientation ratio of the (113) planes gradually increases from the center 111 towards the outer edge 112.

[0055] The orientation ratio of the (113) plane in the cross-section 10 is determined by observing the cross-section 10 with an SEM (Scanning Electron Microscope) and performing crystal analysis using the EBSD method. Specifically, it is determined by analyzing an Inverse Pole Figure (IPF) map, which represents the crystal orientation obtained by the EBSD method using color.

[0056] The following describes an example of an IPF map obtained by the EBSD method, with reference to Figures 3 to 6. Figure 3 shows the distribution of crystal orientations in the cross-section 10, and is a diagram in which the crystal orientations have been converted to shades of grayscale. In an actual IPF map, the crystal orientations are represented by color. A color scale is shown in the upper right of Figure 3. The (001) plane is represented in red, and in Figure 3 it is represented in dark gray. The (101) plane is represented in green, and in Figure 3 it is represented in light gray. The (111) plane is represented in blue, and in Figure 3 it is represented in a slightly darker gray than the red. In Figure 3, for the sake of explanation, a portion of the cross-section 10 including the interior 11 and the exterior 12 is shown. In Figure 3, a portion of the exterior 12 is shown in the area enclosed by the rectangle on the left, a portion of the interior 11 is shown in the area enclosed by the rectangle on the right, and another portion of the interior 11 is shown in the area enclosed by the rectangle in the middle. In Figure 3, the leader line for "IV" points to the left rectangular frame, the leader line for "V" points to the right rectangular frame, and the leader line for "VI" points to the middle rectangular frame.

[0057] Figures 4 to 6 extract crystal orientations from those shown in Figure 3 that are oriented in the direction of the normal to the (113) plane, within the range where the angular difference with respect to the line parallel to the axis of magnetic line 1 is 10° or less. In Figures 4 to 6, crystal orientations that satisfy the above angular difference of 10° or less are represented in colors ranging from dark gray to white, excluding black. A color scale is shown in the upper right corner of each of Figures 4 to 6. In this color scale, the darkest gray is used when the angular difference is 0°, white is used when the angular difference is 10°, and between the angular difference of 0° and 10°, the gray becomes lighter as the angular difference increases.

[0058] Figure 4 is an enlarged view of a portion of the outer 12 in the IPF map shown in Figure 3. This enlarged region is on a straight line passing through the center 111 of the magnetic wire 1, and is a square region with sides of 40 μm centered at a point 17.5% of the distance between the two outer edges 112 on the straight line from the outer edge 112 of the magnetic wire 1. As shown in Figures 1 and 2, when the magnetic wire 1 is a round wire and the shape of the cross-section 10 is circular, the enlarged region is on the diameter D1 of the magnetic wire 1, and is a square region with sides of 40 μm centered at a point 17.5% of the diameter D1 of the magnetic wire 1 from the outer edge 112 of the magnetic wire 1. In the results of Figure 4, the orientation ratio of the (113) plane of the outer 12 is 19.9%.

[0059] Figure 5 is an enlarged view of a portion of the interior 11 shown in Figure 3's IPF map. This first enlarged portion of the interior 11 is a square region with sides of 40 μm centered on the center 111 of the magnetic line 1. In the results of Figure 5, the orientation ratio of the (113) plane in the first region of the interior 11 is 7.31%.

[0060] Figure 6 is an enlarged view of another part of the interior 11 in the IPF map shown in Figure 3. This second enlarged region of the interior 11 lies on a straight line passing through the center 111 of the magnetic wire 1, and is a square region with sides of 40 μm centered at a point 33.75% of the distance between the two outer edges 112 on the straight line from the outer edge 112 of the magnetic wire 1. As shown in Figures 1 and 2, when the magnetic wire 1 is a round wire and the shape of the cross-section 10 is circular, the enlarged second region lies on the diameter D1 of the magnetic wire 1, and is a square region with sides of 40 μm centered at a point 33.75% of the diameter D1 of the magnetic wire 1 from the outer edge 112 of the magnetic wire 1. In the results of Figure 6, the orientation ratio of the (113) plane in the second region of the interior 11 is 10.6%.

[0061] As shown in Figures 4 to 6, the cross-section 10 shown in Figure 3 has a structure in which the orientation ratio of (113) planes in the interior 11 is relatively low, and the orientation ratio of (113) planes in the exterior 12 is relatively high. Furthermore, the orientation ratio of (113) planes in the interior 11 has a structure in which it gradually increases from the center 111 toward the exterior 12. If the orientation ratio of (113) planes in the interior 11 is less than 17% and the orientation ratio of (113) planes in the exterior 12 is 17% or more, the output characteristics are high, as shown in the test example described later. Note that the IPF maps shown in Figures 3 to 6 are the results for sample No. 4 in the test example described later.

[0062] ≪Vickers Hardness≫ The Vickers hardness of magnetic wire 1 is 450 HV or more and 530 HV or less. As described later, magnetic wire 1 is manufactured by drawing and heat-treating a wire material that will become the base material of magnetic wire 1, and then applying torsional stress to the heat-treated material while heating it with an electric current. If the Vickers hardness of magnetic wire 1 is within the above range, tensile residual stress is easily introduced into magnetic wire 1 by the torsional process during the manufacturing of magnetic wire 1, and the output characteristics tend to be high. The Vickers hardness of magnetic wire 1 may also be 470 HV or more and 530 HV or less, 480 HV or more and 520 HV or less, or 490 HV or more and 510 HV or less.

[0063] The Vickers hardness of magnetic wire 1 is determined as follows: In the cross-section 10, the center 111 of magnetic wire 1 and four different points around the center 111 are determined. The four different points around the center 111 are selected from four straight lines that are equally spaced around the center 111, among several straight lines that radiate from the center 111. The points selected from each of the four straight lines are midpoints between the center 111 and the outer edge 112. As shown in Figures 1 and 2, if magnetic wire 1 is a round wire and the shape of the cross-section 10 is circular, the four different points around the center 111 are points that are equally spaced around the center 111 on the circumference of a concentric circle having a diameter of 1 / 2 the diameter D1 of magnetic wire 1. A micro-Vickers hardness test is performed on the center 111 of magnetic wire 1 and the four different points around this center 111, for a total of five points. The average value of the Vickers hardness of the five measured points is considered to be the Vickers hardness of magnetic wire 1. The micro-Vickers hardness test will be conducted in accordance with JIS Z 2244:2009 "Vickers hardness test". The test force will be 0.98 N (0.1 kgf).

[0064] <Twist Marks> As shown in Figure 7, the magnetic wire 1 may have twist marks 4 on its outer surface. The magnetic wire 1 is manufactured by drawing a wire material to produce a drawn wire 6, then heat-treating the drawn wire 6, and then twisting it, as will be described later with reference to Figure 8. Multiple drawing marks are formed on the outer surface of the drawn wire 6 after it has been drawn. Drawing marks are thin, streaky marks that extend in a straight line along the axis of the drawn wire 6. Drawing marks can be caused by friction with the die 81 during the drawing process. Drawing marks are formed along the entire length of the drawn wire 6. When the heat-treated material 7, which is the drawn wire 6, is twisted, the drawing marks deform and twist marks 4 are formed. Twist marks 4 are thin, streaky marks that extend in a spiral on the surface of the magnetic wire 1. Even if there are no drawing marks on the outer surface of the drawn wire 6 after the drawing process, if the heat-treated material 7, which is the drawn wire 6, is subjected to twisting, the surface of the heat-treated material 7 may deform and twist marks 4 may be formed. A magnetic wire 1 having twist marks 4 is more likely to maintain the residual tensile stress introduced into the magnetic wire 1 by the twisting process.

[0065] As shown in Figure 7, the twist marks 4 are inclined with respect to the axis of the magnetic wire 1 when the twisted wire remains twisted. "Remaining in a twisted state" means that the twisting process is completed with the wire in a twisted state. A twisted magnetic wire 1 can be obtained by rotating the wire in only one direction during the twisting process. Alternatively, a twisted magnetic wire 1 can be obtained by rotating the wire clockwise and counterclockwise during the twisting process, such that the total number of clockwise rotations and the total number of counterclockwise rotations are different.

[0066] The angle θt of the twist mark 4 with respect to the axis of the magnetic wire 1 is, for example, 2° to 60°. When the angle θt of the twist mark 4 is within the above range, tensile residual stress along the longitudinal direction of the magnetic wire 1 is easily introduced uniformly along the entire length of the magnetic wire 1. As a result, the output characteristics of the magnetic wire 1 tend to be higher. The angle θt of the twist mark 4 may also be 4° to 60°, 5° to 55°, or 20° to 40°.

[0067] The angle θt of the twist marks 4 is determined as follows: Observe the outer surface of the magnetic wire 1 with an optical microscope. Measure the inclination angle of the twist marks 4 with respect to the axis of the magnetic wire 1. Measure the inclination angles of 20 or more twist marks 4 and take the average value as the angle θt of the twist marks 4.

[0068] ≪Shape≫ The shape of the magnetic wire 1 can be selected as appropriate. The magnetic wire 1 shown in Figure 1 is a round wire. The shape of the cross-section 10 shown in Figure 2 is circular. The shape of the cross-section 10 may also be non-circular. Non-circular shapes include, for example, polygonal shapes, flattened shapes, or elliptical shapes. Polygonal shapes include, for example, quadrilaterals or hexagons. Quadrilaterals include rectangles, squares, trapezoids, rhombuses, etc. Elliptical shapes here also include oblong shapes. An oblong shape is a so-called racetrack shape, consisting of two parallel lines and two semicircular arcs connecting the ends of the two lines. The lengths of the two lines are equal. The lengths of the two semicircular arcs are equal. Flattened shapes here refer to all shapes that are flatter than a perfect circle. Flattened shapes include rectangular and elliptical shapes, etc.

[0069] ≪Size≫ The diameter D1 of the magnetic wire 1 can be selected as appropriate. The diameter D1 of the magnetic wire 1 is the diameter of a circle having an area equal to the area of ​​the cross-section 10. The diameter D1 of the magnetic wire 1 is, for example, 0.1 mm or more and 1.0 mm or less. A magnetic wire 1 with a diameter D1 within the above range can be suitably used as a core for magnetic sensors and the like. The diameter D1 of the magnetic wire 1 may also be 0.15 mm or more and 0.8 mm or less, or 0.2 mm or more and 0.6 mm or less.

[0070] The area of ​​the cross-section 10 can be selected as appropriate. For example, the area of ​​the cross-section 10 is 0.007 mm². ２ The above is 0.800 mm ２ The following applies: A magnetic wire 1 whose cross-sectional area 10 is within the above range can be suitably used as a core for a magnetic sensor or the like. The area of ​​the cross-sectional area 10 is 0.017 mm². ２ The above is 0.510 mm ２ The following, or 0.030 mm ２ Above 0.300 mm ２ The following is also acceptable.

[0071] The length L1 of the magnetic wire 1 can be selected as appropriate. The length L1 of the magnetic wire 1 is the length from the first end to the second end of the magnetic wire 1. For example, the length L1 of the magnetic wire 1 is 3 mm or more and 25 mm or less. A magnetic wire 1 with a length L1 within the above range can be suitably used as a core for a magnetic sensor or the like. The length L1 of the magnetic wire 1 may also be 4 mm or more and 20 mm or less, or 5 mm or more and 15 mm or less.

[0072] Generally, if the diameter D1 of the magnetic wire 1 is small or the length L1 of the magnetic wire 1 is short, the volume of the magnetic wire 1 decreases, which tends to lower the output of the magnetic wire 1. If the length L1 of the magnetic wire 1 is short, the effect of the demagnetizing field becomes larger, which tends to cause fluctuations in the output of the magnetic wire 1. The magnetic wire 1 of the embodiment provides high output and low output fluctuation. Therefore, even if the diameter D1 of the magnetic wire 1 is small or the length L1 of the magnetic wire 1 is short, a stable output can be easily obtained. The magnetic wire 1 of the embodiment has sufficient output characteristics even if the diameter D1 is small or the length L1 is short. When a magnetic wire 1 with a diameter D1 and length L1 within the above range is used as the core of a magnetic sensor, the magnetic sensor can be miniaturized. Magnetic sensors can be used in, for example, magnetic encoders, motors, water meters, generators, etc.

[0073] <Method for Manufacturing Magnetic Wire> The method for manufacturing the magnetic wire 1 of this embodiment will be described with reference to Figure 8. The method for manufacturing the magnetic wire 1 of this embodiment comprises a first step of producing a drawn wire 6 from a material 5, a second step of producing a heat-treated material 7 from the drawn wire 6, and a third step of producing the magnetic wire 1 from the heat-treated material 7. The magnetic wire 1 is obtained by sequentially producing the drawn wire 6 and the heat-treated material 7 from the material 5.

[0074] ≪First Process≫ In the first process, as shown in the upper diagram of Figure 8, a drawn wire 6 is produced by drawing the material 5. The material 5 is made of an alloy mainly composed of iron and cobalt. The composition of the alloy forming the material 5 includes vanadium and manganese as additive elements other than iron and cobalt. The composition of the alloy forming the material 5 is the same as the composition of the magnetic wire 1 described above. The composition of the material 5 is the same as the composition of the magnetic wire 1 to be manufactured. The melting point of the material 5 is higher than the temperature of the heat treatment performed in the second process. The melting point of the material 5 is, for example, about 1300°C. The material 5 is, for example, a cast material or an extruded material. Cast materials include continuously cast materials and continuously cast rolled materials. The material 5 may also be a continuously cast material. Continuously cast rolled materials have less variation in structure and higher productivity. The material 5 may also be a hot forged material that is forged while being heated to a high temperature after casting.

[0075] Drawing is a method of processing a material 5 into a wire using a die 81. Drawing includes not only the normal drawing process in which the material 5 is passed through the holes of a die, but also drawing using a roller die or drawing using a Turkshead. When drawing is performed at a cold temperature, it is easier to obtain a drawn wire 6 with high dimensional accuracy.

[0076] The drawing process involves processing the material 5 into a drawn wire 6 of a predetermined shape, so that the diameter of the drawn wire 6 is a predetermined diameter. The cross-sectional shape of the drawn wire 6 is the same as the cross-sectional shape 10 of the magnetic wire 1 to be manufactured. The diameter of the drawn wire 6 is the same as the diameter D1 of the magnetic wire 1 to be manufactured. The drawing process may be performed multiple times until the diameter of the drawn wire 6 reaches a predetermined diameter. When multiple drawing processes are performed, heat treatment may be performed in the middle of the drawing process. This heat treatment is mainly intended to soften the wire during the drawing process and improve its workability. This heat treatment is called intermediate heat treatment. The temperature of the intermediate heat treatment is, for example, 750°C to 1100°C. The higher the temperature of the intermediate heat treatment, the easier it is to improve workability. The temperature of the intermediate heat treatment may be 780°C to 900°C, or 780°C to 850°C. The time of the intermediate heat treatment is, for example, 10 minutes to 720 minutes. The intermediate heat treatment may be performed under a hydrogen atmosphere. After the intermediate heat treatment, the wire is cooled. The cooling rate after the intermediate heat treatment is, for example, 1°C / second or more. The cooling rate may also be 5°C / second or more, or 10°C / second or more. The faster the cooling rate, the easier it is to improve the workability of the wire. If the cooling rate is too slow, regular transformation will occur, resulting in poor workability of the wire.

[0077] The first step may include a step in which the material 5 is drawn to a degree of processing of 10% or more when processing the material 5 into a drawn wire 6. This degree of processing is, if the above intermediate heat treatment is performed, the degree of processing from the last intermediate heat treatment to the final drawing. When the above intermediate heat treatment is performed, the degree of processing is the ratio obtained by dividing the difference between the cross-sectional area of ​​the wire at the stage when the last intermediate heat treatment is performed and the cross-sectional area of ​​the drawn wire 6 after the final drawing by the cross-sectional area of ​​the wire at the stage when the last intermediate heat treatment is performed. If the above intermediate heat treatment is not performed, the above degree of processing is the same as the total degree of processing from the start to the end of the drawing process. The total degree of processing is the ratio obtained by dividing the difference between the cross-sectional area of ​​the material before drawing and the cross-sectional area of ​​the drawn wire 6 after the final drawing by the cross-sectional area of ​​the material before drawing. By having the above degree of processing of 10% or more, it is easier to control the structure of the drawn wire 6 to become the desired structure. The above degree of processing may be 30% or more, or 40% or more. The upper limit of the total processing degree depends on the diameter of the material 5 or the diameter of the drawn wire 6 to be produced, but for example, it is 99.99%. The total processing degree may also be 10% to 99.99%, 30% to 99.9%, or 40% to 99.5%.

[0078] ≪Second Step≫ In the second step, as shown in the middle diagram of Figure 8, the drawn wire 6 is heat-treated to produce a heat-treated material 7. The heat treatment is performed, for example, in a furnace 82. The heat treatment temperature is, for example, between 750°C and 850°C. If the heat treatment temperature is too low, it will be difficult to twist the heat-treated material 7 in the third step. The optimal temperature range for heat treatment varies depending on the composition of the alloy. For example, in the case of a composition containing 42.0% to 63.0% by mass of cobalt, and especially between 45.0% and 55.0% by mass, the heat treatment temperature is, for example, between 760°C and 840°C, between 780°C and 820°C, or between 790°C and 810°C. The heat treatment time is, for example, between 10 minutes and 720 minutes. The heat treatment may be performed in batches or continuously.

[0079] After heat treatment, the heat-treated material 7 is cooled to room temperature. The room temperature is 20°C ± 15°C. The cooling rate after heat treatment is, for example, 1°C / second or more. The cooling rate may also be 5°C / second or more, or 10°C / second or more.

[0080] ≪Third Step≫ In the third step, as shown in the lower diagram of Figure 8, a magnetic wire 1 is produced by applying torsional stress to the heat-treated material 7 while heating it with an electric current. Torsion stress is applied to the heat-treated material 7 by twisting it. Twisting refers to twisting the heat-treated material 7 around its axis of rotation. Twisting is performed, for example, by gripping both ends of the heat-treated material 7 with chucks 91 and 92 and rotating one of the chucks 91. Before twisting, the heat-treated material 7 is cut to a suitable length so that it can be twisted while gripped with chucks 91 and 92. By twisting the heat-treated material 7, a magnetic wire 1 with high output characteristics can be obtained. Twisting causes a processing-induced transformation. With the rotation of the twisting process stopped, the heat-treated material 7 is heated with an electric current while still gripping it with chucks 91 and 92. In other words, the heat-treated material 7 is subjected to torsional stress while being heated by electric current. The wire, which has been heated by electric current while torsional stress is applied, is cut to a predetermined length. This predetermined length is the same as the length of the magnetic wire 1.

[0081] The twisting process may be performed under conditions such that the amount of strain on the outer surface of the twisted heat-treated material 7 is between 1.0 and 4.5. By performing the twisting process so that the above amount of strain is between 1.0 and 4.5, magnetic wires 1 with high output characteristics can be stably manufactured. The above amount of strain may also be between 1.5 and 4.0.

[0082] Referring to Figure 1, the method for determining the amount of strain will be explained. Here, the magnetic wire 1 shown in Figure 1 is considered to be the heat-treated material 7. The amount of strain δ is calculated as rθ / L1. The radius of the heat-treated material 7 is represented by r. The unit of radius r is mm. Radius r is D1 / 2. The twist angle is represented by θ. The unit of twist angle θ is rad. When the heat-treated material 7 is twisted one full turn, the twist angle θ is 2π. The length of the heat-treated material 7 is represented by L1. The unit of length L1 is mm.

[0083] The strain amount is determined by the total number of rotations, in addition to the radius r and the length L1 of the heat-treated material 7. A specific example of the method for determining the strain amount will be described. In this description, the radius r of the heat-treated material 7 is 0.15 mm, and the length L1 is 30 mm. When the heat-treated material 7 is twisted under the condition of 30 clockwise rotations followed by 30 counterclockwise rotations, the strain amount δ is (30 + 30) × {0.15 × 2π / 30} = 60 × 0.01π, which is approximately 1.8. When the heat-treated material 7 is twisted in the order of 15 clockwise rotations, 30 counterclockwise rotations, and 15 clockwise rotations, the strain amount δ is (15 + 30 + 15) × {0.15 × 2π / 30} = 60 × 0.01π, which is approximately 1.8. These two conditions have the same total number of rotations by twisting, and the same total number of clockwise rotations and total number of counterclockwise rotations.

[0084] The conditions for the twisting process can be changed as appropriate. For example, a set of operations of twisting a clockwise rotations and b counterclockwise rotations may be repeated for a plurality of sets. Alternatively, a set of operations of twisting in the order of c clockwise rotations, d counterclockwise rotations, and e clockwise rotations may be repeated for a plurality of sets. Further, the total number of clockwise rotations and the total number of counterclockwise rotations may be different. The electric heating is performed in a state where the final rotation is stopped.

[0085] In the electric heating, the heat-treated material 7 is caused to generate heat directly by passing an electric current directly through the heat-treated material 7. In the electric heating, electrodes 93 and 94 are arranged at both ends of the heat-treated material 7, and an electric current is passed through the electrodes 93 and 94. The electric heating is performed at 18.0 A / mm ２ exceeding 22.0 A / mm ２ or less current density for a predetermined time. When the current density of the electric heating is 18.0 A / mm ２ exceeding, the heat-treated material 7 generates heat to a predetermined temperature, and tensile residual stress is easily introduced into the heat-treated material 7 by the twisting process. Since the tensile residual stress is easily introduced into the heat-treated material 7, the Vickers hardness of the obtained magnetic wire 1 is 470 HV or more. Since the tensile residual stress is easily introduced into the heat-treated material 7, the obtained magnetic wire 1 has high output characteristics. The current density of the electric heating is 22.0 A / mm ２If the following conditions are met, the temperature of the heat-treated material 7 will not become too high, and a structure will be formed in which the orientation ratio of the (113) planes of the interior 11 is less than 17% and the orientation ratio of the (113) planes of the exterior 12 is 17% or more. The current density for electrical heating is 18.5 A / mm². ２ 21.5A / mm or more ２ Below, 19.0A / mm ２ 21.0A / mm or more ２ The following, or 19.5 A / mm ２ 20.5A / mm or more ２ The following is also acceptable.

[0086] The time for electrical heating is, for example, 35 seconds or more and 55 seconds or less. If the time for electrical heating is 35 seconds or more, the heat-treated material 7 is heated to a predetermined temperature, and the Vickers hardness of the resulting magnetic wire 1 tends to be high. If the time for electrical heating is 55 seconds or less, the temperature of the heat-treated material 7 does not become too high, and a structure is easily formed in the cross-section 10 that satisfies the conditions that the orientation ratio of the (113) planes of the interior 11 is less than 17% and the orientation ratio of the (113) planes of the exterior 12 is 17% or more. The time for electrical heating may also be 40 seconds or more and 50 seconds or 42 seconds or more and 48 seconds or less.

[0087] The temperature reached by the heat-treated material 7 by electric heating is, for example, 90°C or more and less than 150°C. The temperature of the heat-treated material 7 by electric heating can be measured with an infrared thermal camera. If the temperature of the heat-treated material 7 by electric heating is 90°C or higher, the Vickers hardness of the resulting magnetic wire 1 tends to be high. If the temperature of the heat-treated material 7 by electric heating is less than 150°C, the temperature of the heat-treated material 7 does not become too high, and a structure is easily formed in the cross-section 10 that satisfies the conditions that the orientation ratio of the (113) planes of the interior 11 is less than 17% and the orientation ratio of the (113) planes of the exterior 12 is 17% or more. The temperature of the heat-treated material 7 by electric heating may also be 95°C or more and 140°C or less, or 100°C or more and 130°C or less.

[0088] In this example, when applying electric current to the heat-treated material 7 for a predetermined time, the current density for electric current heating should be appropriately selected so that the temperature of the heat-treated material 7 falls within the above range.

[0089] In the case of electric heating, the heating rate may be set to 10°C / s or higher. If the heating rate is 10°C / s or higher, the heat-treated material 7 is heated rapidly, and a structure is easily formed in the cross-section 10 where the orientation ratio of the (113) planes of the interior 11 is less than 17% and the orientation ratio of the (113) planes of the exterior 12 is 17% or higher. The heating rate may also be 15°C / s or higher. The upper limit of the heating rate is, for example, 150°C / s or less.

[0090] The heat-treated material 7, which has been heated by electrical current, is cooled to a predetermined temperature. The cooling rate at this time is, for example, 10°C / s or higher. If the cooling rate is 10°C / s or higher, the heat-treated material 7 that has been heated by electrical current is cooled rapidly, and the structure formed by electrical current heating is more likely to be maintained even after cooling. The cooling rate may also be 11°C / s or higher, or 12°C / s or higher. The upper limit of the cooling rate is, for example, 150°C / s or lower.

[0091] The heat-treated material 7, which is subjected to electric heating while applying torsional stress, is the magnetic wire 1 described above. By performing electric heating while applying torsional stress, the orientation ratio of the (113) planes in the cross-section 10 of the magnetic wire 1 satisfies specific conditions, and the Vickers hardness satisfies a specific range. When the orientation ratio of the (113) planes in the cross-section 10 satisfies specific conditions and the Vickers hardness satisfies a specific range, the output characteristics of the magnetic wire 1 are improved.

[0092] <Composite Magnetic Wire> The composite magnetic wire 2 of the embodiment will be described with reference to Figure 9. The composite magnetic wire 2 comprises the magnetic wire 1 described above and a metallic coating material 3. The coating material 3 is arranged on the outer surface of the magnetic wire 1. The outer surface of the magnetic wire 1 and the inner surface of the coating material 3 are in direct contact.

[0093] The metal forming the coating material 3 is, for example, iron, iron alloy, copper, copper alloy, aluminum, aluminum alloy, nickel, or nickel alloy. Iron alloys are, for example, stainless steel or carbon steel. Stainless steel is, for example, SUS403, SUS430, SUS304, SUS316, SUS304L, or SUS316L. Copper alloy is, for example, phosphor bronze. Nickel alloy is, for example, permalloy, nitinol, or nichrome. The coating material 3 may be magnetic or non-magnetic. The material of the coating material 3 can be determined, for example, from the results of compositional analysis of the coating material 3 by EDX.

[0094] The composite magnetic wire 2 is manufactured, for example, by drawing and heat-treating a coated wire in which a metal coating material 3 is placed on the outer surface of the wire material that will be used as the base for the magnetic wire 1, and then by applying torsional stress to the heat-treated material while heating it with electricity. When a metal coating material 3 is placed on the outer surface of the magnetic wire 1, tensile residual stress is easily introduced into the magnetic wire 1 by the torsional process during the manufacturing of the composite magnetic wire 2, and the output characteristics of the magnetic wire 1 tend to be higher. As a result, the composite magnetic wire 2 tends to produce high output.

[0095] The coating material 3 is clad on the outer surface of the magnetic wire 1, for example. In this example, the coating material 3 is joined to the outer surface of the magnetic wire 1 in a state where a cylindrical coating material 3 is fitted onto it. The coating material 3 may also be plated onto the outer surface of the magnetic wire 1.

[0096] The melting point of the coating material 3 is, for example, above 850°C. If the melting point of the coating material 3 is above 850°C, heat treatment can be performed during the manufacturing process of the composite magnetic wire 2. The melting point of the coating material 3 may be 900°C or higher, or 950°C or higher. The melting point of the coating material 3 is determined as follows: Measure the initial size of the composite magnetic wire 2. For example, measure the diameter D2 of the composite magnetic wire 2. Heat and then cool the composite magnetic wire 2. The heating temperature at which the coating material 3 melts and changes shape is taken as the melting point of the coating material 3. If the coating material 3 has not melted, heat the composite magnetic wire 2 to a higher temperature and then cool it. Repeat heating and cooling until the coating material 3 melts. The heating temperature is set, for example, from 100°C to 1300°C in 50°C increments. The time for holding the composite magnetic wire 2 in a heated state is, for example, 5 minutes or more.

[0097] The Vickers hardness of the coating material 3 is, for example, 200 HV or higher. If the Vickers hardness of the coating material 3 is 200 HV or higher, tensile residual stress is easily introduced into the magnetic wire 1 by twisting during the manufacturing process of the composite magnetic wire 2, and the output characteristics of the magnetic wire 1 tend to be higher. The Vickers hardness of the coating material 3 may be 300 HV or higher, or 380 HV or higher. The upper limit of the Vickers hardness of the coating material 3 is, for example, 700 HV or lower. The Vickers hardness of the coating material 3 may be 200 HV to 700 HV, 300 HV to 600 HV, or 380 HV to 480 HV.

[0098] The Vickers hardness of the coating material 3 is determined as follows: The midpoint of the thickness of the coating material 3 is determined in the cross-section of the composite magnetic wire 2. The midpoint of the thickness of the coating material 3 is the midpoint between the inner circumference and the outer circumference of the coating material 3. If the cross-sectional shape of the coating material 3 is cylindrical, the midpoint of the thickness of the coating material 3 is located on the circumference of a concentric circle having a diameter obtained by adding the inner diameter and outer diameter of the coating material 3 and dividing by 2. The inner diameter of the coating material 3 is the diameter D1 of the magnetic wire 1, and the outer diameter of the coating material 3 is the diameter D2 of the composite magnetic wire 2. Micro-Vickers hardness tests are performed on four of the midpoints of the thickness of the coating material 3. The average value of the Vickers hardness of the four measured points is considered to be the Vickers hardness of the coating material 3. The four points are determined to be equally spaced around the central axis of the coating material 3. The method for testing the micro-Vickers hardness of the coating material 3 is the same as the method for testing the micro-Vickers hardness of the magnetic wire 1. However, the test force is 0.098 N (0.01 kgf).

[0099] The ratio of the diameter D1 of the magnetic wire 1 to the diameter D2 of the composite magnetic wire 2 is, for example, 45% to 95%. If the ratio of diameter D1 to diameter D2 is 45% or more, the ratio of the cross-sectional area of ​​the magnetic wire 1 to the cross-sectional area of ​​the composite magnetic wire 2 does not become too small, and the output characteristics of the composite magnetic wire 2 tend to be high. If the ratio of diameter D1 to diameter D2 is 95% or less, the ratio of the cross-sectional area of ​​the coating material 3 to the cross-sectional area of ​​the composite magnetic wire 2 does not become too small. The relatively large ratio of the cross-sectional area of ​​the coating material 3 makes it easier for tensile residual stress to be introduced into the magnetic wire 1 by twisting during the manufacturing process of the composite magnetic wire 2, and the output characteristics of the magnetic wire 1 tend to be high. The ratio of diameter D1 to diameter D2 may also be 48% to 95%, 55% to 90%, or 60% to 85%.

[0100] The shape of the composite magnetic wire 2 can be selected as appropriate. The composite magnetic wire 2 shown in Figure 9 is a round wire. The cross-sectional shape of the composite magnetic wire 2 is circular. The cross-sectional shape of the composite magnetic wire 2 may be non-circular. The cross-sectional shape of the covering material 3 is cylindrical.

[0101] The diameter D2 of the composite magnetic wire 2 can be selected as appropriate. The diameter D2 of the composite magnetic wire 2 is the diameter of a circle having an area equal to the area of ​​the cross-section of the composite magnetic wire 2. For example, the diameter D2 of the composite magnetic wire 2 is between 0.105 mm and 3.0 mm. A composite magnetic wire 2 with a diameter D2 within the above range can be suitably used as a core for magnetic sensors and the like. The diameter D2 of the composite magnetic wire 2 may also be between 0.11 mm and 2.0 mm, between 0.12 mm and 1.0 mm, between 0.15 mm and 0.8 mm, or between 0.2 mm and 0.6 mm.

[0102] The length L2 of the composite magnetic wire 2 can be selected as appropriate. The length L2 of the composite magnetic wire 2 is the length from the first end to the second end of the composite magnetic wire 2. The length L2 of the composite magnetic wire 2 is the same as the length L1 of the magnetic wire 1 described above.

[0103] The composite magnetic wire 2 may have twist marks, which are not shown. The composite magnetic wire 2 is manufactured, for example, by drawing and heat-treating a coated wire in which a metallic coating material 3 is placed on the outer surface of the wire material that will be used as the base material for the magnetic wire 1, and then twisting the heat-treated material. The twist marks are formed by the twisting process. The twist marks formed on the composite magnetic wire 2 are the same as the twist marks 4 formed on the magnetic wire 1 described above.

[0104] <Method for Manufacturing Composite Magnetic Wires> Composite magnetic wires 2 can be manufactured by the same or similar processes as those described above for manufacturing magnetic wire 1. The method for manufacturing composite magnetic wires 2 includes a step of producing a coated wire in which a metal layer coating material 3 is placed on the outer surface of a wire that will be the material for magnetic wire 1. In the method for manufacturing composite magnetic wires 2, the first, second, and third steps described in the method for manufacturing magnetic wire 1 are performed in order on this coated wire.

[0105] In the process of manufacturing coated wires, a coating material 3 is formed on the outer surface of the wire that will be the material for the magnetic wire 1 by a cladding method. The cladding method is a method of joining the coating material 3 to the outer surface of the wire by inserting the wire into a cylindrical coating material 3 and then pulling it out. The thickness of the coating material 3 can be appropriately selected so that the ratio of the diameter D1 of the magnetic wire 1 to the diameter D2 of the composite magnetic wire 2 to be manufactured is within a predetermined range. In the process of manufacturing coated wires, the coating material 3 may also be formed on the outer surface of the wire that will be the material for the magnetic wire 1 by a plating method.

[0106] In the first step of the manufacturing method for the composite magnetic wire 2, a drawn wire 6 is produced by drawing out the coated wire. The first step of the manufacturing method for the composite magnetic wire 2 differs from the first step of the manufacturing method for the magnetic wire 1 described above in that it involves drawing out the coated wire. The drawing process is the same as the drawing process described in the manufacturing method for the magnetic wire 1 described above.

[0107] The second step in the manufacturing method of the composite magnetic wire 2 is the same as the second step in the manufacturing method of the magnetic wire 1 described above.

[0108] The third step in the manufacturing method of the composite magnetic wire 2 is the same as the third step in the manufacturing method of the magnetic wire 1 described above. However, the amount of strain due to twisting in the manufacturing method of the composite magnetic wire 2 is different from the amount of strain due to twisting in the manufacturing method of the magnetic wire 1 described above. In the manufacturing method of the composite magnetic wire 2, the twisting is performed, for example, under conditions such that the amount of strain on the surface of the twisted heat-treated material 7 is between 0.8 and 3.0. By performing the twisting so that the above amount of strain is between 0.8 and 3.0, a composite magnetic wire 2 with high output characteristics can be stably manufactured. The above amount of strain may also be between 1.0 and 2.0. The method for determining the amount of strain of the composite magnetic wire 2 differs from the method for determining the amount of strain of the magnetic wire 1 described above in that the diameter D2 of the composite magnetic wire 2 including the coating material 3 is used. Other than the amount of strain in the third step, it is the same as the third step in the manufacturing method of the magnetic wire 1 described above.

[0109] [Test Examples] In the test examples, the microstructure, Vickers hardness, and power characteristics of magnetic wires or composite magnetic wires manufactured by various manufacturing methods were investigated.

[0110] <Samples> <Samples No. 1 to No. 32, Samples No. 101 to No. 106> Samples No. 1 to No. 32, and Samples No. 101 to No. 106 were manufactured by drawing and heat-treating wire materials that would become the basis for magnetic wires or composite magnetic wires, and then applying torsional stress to the heat-treated material while heating it with an electric current.

[0111] The manufacturing conditions for each sample are as shown in Figure 11. The composition No. in Figure 11 is the composition of the magnetic wire, and refers to the list of magnetic wire compositions shown in Figure 10. The "Coating Material" column in Figure 11 indicates whether or not a coating material is placed on the outer surface of the magnetic wire. If a coating material is placed on the outer surface of the magnetic wire, it is marked "Yes". Samples marked "Yes" are composite magnetic wires. If a coating material is not placed on the outer surface of the magnetic wire, it is marked "No".

[0112] In the composite magnetic wire samples with a coating, the conditions for the coating material are the same. In all samples, the coating material is made of SUS316L. The melting point of the coating material is 1300°C or higher. In all samples, the ratio of the diameter of the magnetic wire to the diameter of the composite magnetic wire is 85%.

[0113] First, drawn wires were produced by drawing a wire that would serve as the material for magnetic wires, or a coated wire in which a metallic coating material was placed on the outer surface of the wire. The shape of the drawn wire was round. That is, the cross-sectional shape of the drawn wire was circular. The diameter of the drawn wire was 5.0 mm. The drawing process was performed cold. Multiple drawing processes were carried out, and intermediate heat treatment was performed during the drawing process. The intermediate heat treatment was performed once when the drawn wire was drawn to a diameter of 1.0 mm. After the intermediate heat treatment, the drawn wire was drawn until its diameter was 0.4 mm. The degree of completion after the intermediate heat treatment and up to the final drawing was 84%. The temperature of the intermediate heat treatment was 800°C. The duration of the intermediate heat treatment was 60 minutes. The intermediate heat treatment was performed in a hydrogen atmosphere. The cooling rate after the intermediate heat treatment was 20°C / second. The total degree of completion was 99.99%.

[0114] Next, heat-treated material was prepared by heat-treating the drawn wire. The heat treatment temperature was set to 800°C. The heat treatment time was set to 60 minutes. The heat treatment was carried out under a hydrogen atmosphere. After the heat treatment, the heat-treated material was cooled to room temperature. The cooling rate after heat treatment was set to 20°C / second.

[0115] Finally, composite magnetic wires were fabricated by applying torsional stress to the heat-treated material while heating it with an electric current. The torsion of the heat-treated material was performed by cutting the material to a length of 55 mm, gripping both ends of the cut material with chucks, and rotating one of the chucks. The length of each end of the heat-treated material gripped by the chucks was set to 2.5 mm so that the distance between the chucks was 50 mm. The length of the portion to be torn was 50 mm. The torsion was performed under conditions such that the amount of strain on the surface of the torn heat-treated material was 1.62. Specifically, each sample was twisted in the following order: 6.3 rotations clockwise, 12.6 rotations counterclockwise, 12.6 rotations clockwise, and 33 rotations counterclockwise.

[0116] For the electric heating process, after the final rotation caused by the twisting process described above had stopped, electrodes were placed at both ends of the cut heat-treated material while it was still held in the chuck, and an electric current was passed through the electrodes. The current density and time for electric heating in each sample are shown in Figure 11. Figure 11 also shows the temperature reached by the heat-treated material through electric heating. The temperature reached by the heat-treated material through electric heating was measured using an infrared thermal camera. Figure 11 also shows the heating rate during electric heating. The heat-treated material that underwent electric heating was cooled to 40°C. The cooling rate is as shown in Figure 11.

[0117] After the heat-treated material, which had been electrically heated, cooled, 20 mm was cut from both ends of a 50 mm wire, and the properties of the remaining 10 mm wire were evaluated. The reason for excluding both ends of the wire from evaluation is that heat escapes from the chuck at both ends, and therefore they are not sufficiently electrically heated.

[0118] ≪Sample No. 107≫ Sample No. 107 was manufactured by drawing and heat-treating a wire that would become the material for a composite magnetic wire, and then twisting the heat-treated material in a furnace without applying electric heating. Sample No. 107 is a composite magnetic wire in which a coating material is placed on the outer surface of the magnetic wire. The composition of the magnetic wire and the conditions of the coating material for Sample No. 107 are the same as those for Sample No. 1.

[0119] Sample No. 107 was manufactured by drawing a coated wire, which had a metal coating placed on its outer surface, to produce a drawn wire. After heat treatment of the drawn wire, a second heat treatment was performed in a furnace while applying torsional stress. Sample No. 107 was not subjected to electric heating. The conditions for drawing, heat treatment, and torsion processing were the same as for Sample No. 1, except that the second heat treatment was performed in a furnace while applying torsional stress without electric heating. In Sample No. 107, the temperature reached in Figure 11 represents the heat treatment temperature in the furnace. In Sample No. 107, the holding time at the reached temperature was 1 minute.

[0120] <Twist Marks> For each sample, the twist marks on the outer surface were examined for the composite magnetic wire if a coating material was placed on the outer surface of the magnetic wire, and for the magnetic wire if no coating material was placed on the outer surface of the magnetic wire. Specifically, the outer surface of the composite magnetic wire or magnetic wire of each sample was observed with an optical microscope, and the inclination angle of the twist marks with respect to the axis of the magnetic wire was measured. The inclination angles of 20 or more twist marks were measured, and the average value was defined as the twist mark angle θt. As a result, for all samples, the twist mark angle θt was within the range of 2° to 60°.

[0121] <Microstructure of Magnetic Lines> The microstructure of the magnetic lines of each sample was determined by EBSD. Specifically, the cross-section of the composite magnetic lines or magnetic lines of each sample was observed using SEM. The EBSD conditions were a step size of 0.2 μm, an acceleration voltage of 15 kV, and a working distance of 15 mm. The crystal orientations obtained by EBSD were represented by an IPF map. First, the interior and exterior were distinguished from the interior based on the colors representing the crystal orientations in the IPF map. In the IPF map, the interior is predominantly green, while the exterior is predominantly red and blue. The color scale of the IPF map is as described above.

[0122] From the internal and external regions identified in the IPF map, we extracted areas for determining the orientation ratio of (113) planes. In this example, two different regions were extracted for determining the orientation ratio of internal (113) planes. The first region is a square region with sides of 40 μm centered on the center of the magnetic line. The second region is a square region with sides of 40 μm centered on the diameter of the magnetic line, at a position 33.75% of the magnetic line's diameter from its outer edge. The region for determining the orientation ratio of external (113) planes is a square region with sides of 40 μm centered on the same diameter of the magnetic line, at a position 17.5% of the magnetic line's diameter from its outer edge. In each region, we determined the proportion of (113) planes in the IPF map that satisfy an angle difference of 10° or less with respect to a line parallel to the axis of the magnetic line. The results are shown in Figure 12.

[0123] <Vickers Hardness> The Vickers hardness of the magnetic wires in each sample was measured. As described above, the Vickers hardness of the magnetic wire is the average of five Vickers hardness measurements taken by performing micro-Vickers hardness tests at four different points: the center of the magnetic wire and the midpoint of the magnetic wire's radius. In samples where a coating material was placed on the outer surface of the magnetic wire, the Vickers hardness of the coating material was also measured. As described above, the Vickers hardness of the coating material is the average of four Vickers hardness measurements taken by performing micro-Vickers hardness tests at four different points: the midpoint of the coating material's thickness. The results are shown in Figure 12.

[0124] <Output Characteristics> The output characteristics of the magnetic wires of each sample were evaluated. The output characteristics were evaluated as follows: A power generation element was fabricated by winding a coil around a magnetic wire or composite magnetic wire. The output of the power generation element was connected to a full-wave rectifier circuit connected to a capacitor and a resistor. An AC magnetic field of 20 Hz was applied to the power generation element connected to the full-wave rectifier circuit in the range of 20 Oe to 200 Oe. In measuring the generated voltage, the peak voltage after rectification of the generated pulse by the power generation element was measured each time the direction of the AC magnetic field was reversed. The peak voltage was measured 2500 times, and the average value of the 2500 measured peak voltages was calculated. This average value of the peak voltage is shown as the output in Figure 12.

[0125] As shown in Figure 12, the output characteristics of samples No. 1 to No. 32 are high, exceeding 2.3V, and especially 2.7V or higher. Samples No. 1 to No. 32 satisfy all three of the following conditions (A), (B), and (C): (A) The alloy forming the magnetic wire contains a specific composition. (B) The orientation ratio of the internal (113) planes is less than 17%, and the orientation ratio of the external (113) planes is 17% or more. (C) The Vickers hardness of the magnetic wire is in the range of 450 HV to 530 HV. Condition (B) above is satisfied when a torsional stress of 18.0 A / mm is applied. ２ Ultra-high 22.0 A / mm ２ Because the following current densities were used for heating, it is thought that a structure was formed in which the orientation ratio of (113) planes was relatively low inside and relatively high outside. In particular, it is thought that a structure was formed in which the orientation ratio of (113) planes was relatively high, at 17% or more on the outside. It can be seen that the orientation ratio of (113) planes tends to increase gradually from the center of the magnetic line towards the outer edge.

[0126] Sample No. 101 exhibited a low Vickers hardness of 440 HV and a low output characteristic of 2.1 V. Sample No. 101 had a low current density during electrical heating. Therefore, it is thought that the heat-treated material was difficult to heat to the required temperature, and that tensile residual stress due to twisting was not easily introduced into the heat-treated material. This difficulty in introducing tensile residual stress into the heat-treated material likely resulted in the low Vickers hardness of the magnetic wire (440 HV).

[0127] Sample No. 102 exhibited a high Vickers hardness of 570 HV, a low orientation ratio of less than 17% for the external (113) planes, and a low output characteristic of 2.1 V. Sample No. 102 had a high current density during electrical heating. Therefore, it is thought that the temperature of the heat-treated material became too high, and excessive tensile residual stress due to twisting was introduced into the heat-treated material, resulting in an excessively high Vickers hardness. Furthermore, it is thought that the excessively high temperature of the heat-treated material caused the external (113) planes to tilt to an angle of more than 10° with respect to a line parallel to the axis of the magnetic wires due to the twisting process.

[0128] In sample No. 103, the orientation ratio of the external (113) plane was low at less than 17%, and the output characteristic was low at 2.1V. In sample No. 103, the current density during electric heating was 20.0 A / mm². ２ However, the heating time was long. As a result, the temperature of the heat-treated material became too high, and it is thought that the twisting process caused the outer (113) surface to tilt at an angle of more than 10° with respect to a line parallel to the axis of the magnetic wire.

[0129] In sample No. 104, the alloy forming the magnetic wire had a low manganese content, resulting in a low output characteristic of 1.3V. In sample No. 105, the alloy forming the magnetic wire had a high vanadium content, resulting in a low output characteristic of 2.0V. In sample No. 106, the alloy forming the magnetic wire had a low vanadium content, resulting in a low output characteristic of 1.5V. This shows that the composition of the alloy forming magnetic wire 1 affects the output characteristics.

[0130] In sample No. 107, heat treatment was performed in a furnace rather than by electric heating, resulting in slow heating and cooling rates. This likely made it difficult to form a structure where the proportion of external (113) surfaces was 17% or more.

[0131] From these results, it was found that by applying torsional stress while heating with a specific current density and time, a structure can be formed in the cross-section of the magnetic wire in which the orientation ratio of the internal (113) planes is less than 17% and the orientation ratio of the external (113) planes is 17% or more. Furthermore, it was found that by applying torsional stress while heating with a specific current density and time, the Vickers hardness of the magnetic wire can be made between 450 HV and 530 HV. It was found that the output characteristics of the magnetic wire are enhanced when the alloy forming the magnetic wire contains a specific composition, the orientation ratio of the (113) planes in the cross-section satisfies specific conditions, and the Vickers hardness satisfies a specific range.

[0132] 1 Magnetic wire 10 Cross-section 11 Interior 111 Center 112 Outer edge 12 Exterior 2 Composite magnetic wire 3 Coating material 4 Twist mark 5 Material 6 Drawn wire 7 Heat-treated material 81 Die 82 Furnace 91, 92 Chuck 93, 94 Electrode D1, D2 Diameter, L1, L2 Length, r Radius θ Twist angle, θt Angle of twist mark

Claims

1. A magnetic wire made of an alloy mainly composed of iron and cobalt, wherein the alloy contains 6.5% by mass or more and 10.5% by mass or less of vanadium and 0.3% by mass or more and 1.2% by mass or less of manganese, the cross-section of the magnetic wire has an interior and an exterior, the interior is a region in which the proportion of the crystal orientation in the longitudinal direction of the magnetic wire being normal to the (113) plane is less than 17%, the exterior is a region in which the proportion of the crystal orientation in the longitudinal direction of the magnetic wire being normal to the (113) plane is 17% or more, and the Vickers hardness is 450 HV or more and 530 HV or less.

2. The magnetic wire according to claim 1, wherein the alloy contains more than 0.0% by mass and 0.4% by mass or less of silicon.

3. The magnetic wire according to claim 1 or claim 2, wherein the alloy contains 0.2% by mass or more and 0.8% by mass or less of aluminum.

4. The magnetic wire according to claim 3, wherein the alloy contains 0.02% by mass or more and 0.15% by mass or less of titanium.

5. The magnetic wire according to any one of claims 1 to 4, wherein the weight ratio of cobalt to iron, Co / Fe, is 1.20 or more and 1.45 or less.

6. The magnetic wire according to any one of claims 1 to 5, wherein the magnetic wire has a twist mark on its outer surface, and the angle of the twist mark with respect to the axis of the magnetic wire is 2° or more and 60° or less.

7. The magnetic wire according to any one of claims 1 to 6, wherein the diameter of the magnetic wire is 0.1 mm or more and 1.0 mm or less, and the length of the magnetic wire is 25 mm or less.

8. A composite magnetic wire comprising a magnetic wire according to any one of claims 1 to 7, and a metallic coating material disposed on the outer surface of the magnetic wire.

9. The composite magnetic wire according to claim 8, wherein the ratio of the diameter of the magnetic wire to the diameter of the composite magnetic wire is 45% or more and 95% or less.

10. The composite magnetic wire according to claim 8 or claim 9, wherein the melting point of the coating material is greater than 850°C.

11. The composite magnetic wire according to any one of claims 8 to 10, wherein the Vickers hardness of the coating material is 200 HV or more.

12. The process comprises: a step of drawing a wire from a material made of an alloy mainly composed of iron and cobalt; a step of heat-treating the wire to produce a heat-treated material; and a step of heating the heat-treated material with an electric current while applying torsional stress to produce a magnetic wire, wherein the alloy contains 6.5% by mass or more and 10.5% by mass or less of vanadium and 0.3% by mass or more and 1.2% by mass or less of manganese, and the electric current heating is 18.0 A / mm ２ Ultra-high 22.0 A / mm ２ A method for manufacturing magnetic wires, performed for a predetermined time at the following current densities.

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