Magnesium wire, method for producing magnesium wire, and method for evaluating magnesium wire

Abstract

The present invention provides a magnesium wire which has high flexibility and which is hardly broken even when the magnesium wire has complex shape deformation.　The magnesium wire according to the present invention contains magnesium as a main component, and in crystal grains constituting the magnesium wire, the proportion of crystal grains having a KAM value of 0° or more and less than 1° is 70% or more.

Description

Magnesium wire, magnesium wire manufacturing method, and magnesium wire evaluation method

[0001] The present invention relates to a magnesium wire containing magnesium as a main component, a method for manufacturing the magnesium wire, and a method for evaluating the magnesium wire.

[0002] In recent years, attention has been focused on the biocompatibility and bioabsorbability of magnesium, and high-purity magnesium and highly biosafe magnesium alloys are expected to be used in the medical field. Medical devices made from magnesium are absorbed into the body as the magnesium corrodes and dissolves in bodily fluids as the body tissue heals and settles, or after the period required for healing and settling has passed. This eliminates the need for a second surgery to remove the medical device after a certain period of time has passed since its implantation, greatly reducing the burden on the patient.

[0003] Patent Document 1 discloses a magnesium-based alloy wire containing magnesium as a main component and a method for producing the same.

[0004] Japanese Patent Application Laid-Open No. 2003-293069

[0005] For example, magnesium wire, which is primarily composed of magnesium, is being considered as a medical device for suturing incisions. However, magnesium is a material that generally lacks ductility due to its close-packed hexagonal lattice crystal structure. Therefore, magnesium wire, which is a thin wire, has the technical challenge of breaking when subjected to complex shape deformation.

[0006] An object of the present invention is to provide a magnesium wire having high flexibility, a method for manufacturing the magnesium wire, and a method for evaluating the magnesium wire.

[0007] As a result of extensive research, the inventors of the present invention have found that the amount of residual strain contained in the crystal grains constituting the magnesium wire has a significant effect on the flexibility of the magnesium wire, i.e., the ease with which the magnesium wire undergoes plastic deformation.

[0008] The KAM (Kernel Average Misorientation) value, which is the average value of the crystal orientation difference between a measurement point and its neighboring measurement points, is known as a value related to the "amount of residual strain contained within a crystal grain." A large KAM value indicates a large amount of residual strain contained within a crystal grain, while a small KAM value indicates a small amount of residual strain contained within a crystal grain.

[0009] As a result of further investigation, the inventors of the present invention have reached the finding that when the proportion of crystal grains having a KAM value of less than 1° among the crystal grains constituting the magnesium wire is 70% or more, a magnesium wire having high flexibility that is difficult to break even when subjected to complex shape deformation can be obtained.

[0010] That is, the magnesium wire according to the present invention is a magnesium wire containing magnesium as a main component, and is characterized in that the proportion of crystal grains constituting the magnesium wire whose KAM value is 0° or more and less than 1° is 70% or more.

[0011] This makes it possible to obtain a magnesium wire that is highly flexible and difficult to break even when subjected to complex shape deformation.

[0012] The method for manufacturing magnesium wire according to the present invention is a method for manufacturing magnesium wire that is thinned by repeatedly performing drawing or extrusion, and is characterized in that magnesium wire is manufactured in which the proportion of crystal grains with a KAM value of 0° or more and less than 1° is 70% or more without performing annealing treatment in each drawing or extrusion process.

[0013] This makes it possible to obtain a magnesium wire that is highly flexible and difficult to break even when complex shape deformation is involved, without performing an annealing treatment in each step of the drawing or extrusion process.

[0014] The magnesium wire evaluation method according to the present invention is a method for evaluating the flexibility of a magnesium wire whose main component is magnesium, and is characterized in that the evaluation is based on the proportion of crystal grains that have a KAM value of 0° or more and less than a predetermined value among the crystal grains that make up the magnesium wire.

[0015] This allows a new evaluation method that has not been available before, that is, an accurate evaluation of the flexibility of magnesium wire based on the proportion of crystal grains whose KAM value is less than a predetermined value.

[0016] As described above, according to the present invention, it is possible to obtain a magnesium wire having high flexibility and being resistant to breakage even when it is subjected to complex shape deformation.

[0017] 1 is a diagram illustrating samples used in an evaluation test of magnesium wires according to an embodiment of the present invention. A table illustrating (Sample N1) to (Sample N9) is shown. It shows the measurement results of the distribution of KAM values ​​within the crystal of (Sample N1). It shows the measurement results of the distribution of KAM values ​​within the crystal of (Sample N2). It shows the measurement results of the distribution of KAM values ​​within the crystal of (Sample N3). It shows the measurement results of the distribution of KAM values ​​within the crystal of (Sample N4). It shows the measurement results of the distribution of KAM values ​​within the crystal of (Sample N5). It shows the measurement results of the distribution of KAM values ​​within the crystal of (Sample N6). It shows the measurement results of the distribution of KAM values ​​within the crystal of (Sample N7). It shows the measurement results of the distribution of KAM values ​​within the crystal of (Sample N8). It shows the measurement results of the distribution of KAM values ​​within the crystal of (Sample N9). It shows the evaluation results of flexibility of (Sample N4). It shows the evaluation results of flexibility of (Sample N8). It shows the evaluation results of stitch size of (Sample N4). 1 is a diagram showing the evaluation results of the stitch size for (Sample N8). FIG. 2 is a table summarizing the evaluation results for (Sample N1) to (Sample N9).

[0018] Hereinafter, a magnesium wire according to an embodiment of the present invention will be described with reference to the drawings.

[0019] The inventors of the present invention analyzed the amount of residual strain contained within the crystal grains constituting magnesium wire samples used as biodegradable medical devices using the electron backscatter diffraction (EBSD) method. Specifically, they measured the KAM (kernel average misorientation) value, which is a value related to the "amount of residual strain contained within the crystal grains constituting the magnesium wire." The KAM value is the average value of the crystal orientation misorientation between a measurement point and its adjacent measurement points. The KAM value can be determined by measuring the crystal orientation misorientation between adjacent measurement points obtained by the EBSD method.

[0020] The equipment used to measure the KAM value using the EBSD method is as follows: {SEM} Scanning electron microscope (SEM) JEOL Ltd. JSM-IT300HR(LA) {EBSD data collection software (software for controlling the SEM stage, calculating crystal orientation, etc.)} TSL Solutions Co., Ltd. OIM Data Collection {EBSD data analysis software (software for analyzing collected data in detail and creating maps, graphs, etc.)} TSL Solutions Co., Ltd. OIM Analysis

[0021] The KAM value was measured by measuring the distribution of KAM values ​​in a partial range included in an arbitrary cross section 10 in the longitudinal direction of a long magnesium wire 1 having a circular cross section as shown in Figure 1. In this embodiment, the distribution of KAM values ​​was measured in a partial range included in the cross section 10, but the measured distribution of KAM values ​​is considered to be approximately the same as the distribution of KAM values ​​in the entire range of the cross section 10.

[0022] Nine types of magnesium wires, designated Samples N1 to N9, were used, as shown in Figure 2. For Samples N1 to N3, Samples N5 to N7, and Sample N9, the KAM distribution was measured within a region 12a corresponding to the radius of the cross section 10 (the region 12a extending from the specified outer surface toward the center), as shown in Figure 1(a). For Samples N4 and N8, the KAM distribution was measured within a region 12b corresponding to the diameter of the cross section 10 (the region 12b extending from the specified outer surface through the center toward the outer surface opposite the specified outer surface), as shown in Figure 1(b). Note that Samples N4 and N8 were drawn, thin wires with a very small diameter (0.2 mm), and the area of ​​the region 12a corresponding to the radius of the cross section 10 was small, making measurement difficult. Therefore, the KAM distribution was measured within a region 12b corresponding to the diameter of the cross section 10.

[0023] (Sample N1): "High-purity extruded material φ3.0" (Sample N1) is an extruded material φ3.0 mm with a magnesium purity of 99.995% or more, which has not been annealed after extrusion.

[0024] (Sample N2): "High-purity drawn material φ2.0" (Sample N2) is a drawn material φ2.0 mm with a magnesium purity of 99.995% or more. More specifically, it was obtained by repeatedly drawing a φ3.0 mm extruded material (Sample N1) down to φ2.0 mm without annealing in between each stage, and was not annealed after the final drawing process.

[0025] (Sample N3): "High-purity drawn material φ1.0" (Sample N3) is a drawn material φ1.0 mm with a magnesium purity of 99.995% or more. More specifically, it is obtained by repeatedly drawing a φ2.0 mm extruded material (not shown as a sample in this embodiment) that has not been annealed after extrusion down to φ1.0 mm without annealing at each stage, and is not annealed after the final drawing.

[0026] (Sample N4): "High-purity drawn material φ0.2" (Sample N4) is a drawn material φ0.2 mm with a magnesium purity of 99.995% or more. More specifically, it was obtained by repeatedly drawing a drawn material φ1.0 mm (Sample N3) down to φ0.2 mm without annealing in between each stage, and was not annealed after the final drawing process.

[0027] (Sample N5): "Low-purity drawn material φ2.0 (annealed for 30 minutes)" (Sample N5) is a drawn material φ2.0 with a magnesium purity of 99.9669% or less, and more specifically, it is a drawn material φ2.0 mm (Sample N9) that has been annealed at 250°C for 30 minutes.

[0028] (Sample N6): "Low-purity drawn material φ2.0 (annealed for 60 minutes)" (Sample N6) is a drawn material φ2.0 with a magnesium purity of 99.9669% or less, and more specifically, it is a drawn material φ2.0 mm (Sample N9) that has been annealed at 250°C for 60 minutes.

[0029] (Sample N7): "Low-purity drawn material φ2.0 (annealed for 120 minutes)" (Sample N7) is a drawn material φ2.0 with a magnesium purity of 99.9669% or less, and more specifically, it is a drawn material φ2.0 mm (Sample N9) that has been annealed at 250°C for 120 minutes.

[0030] (Sample N8): "Low-purity drawn material φ0.2 (unannealed)" This is a φ0.2mm drawn material with a magnesium purity of 99.9669% or less. Specifically, it was obtained by repeatedly drawing raw material with a magnesium purity of 99.9669%, with annealing during each stage, until it was φ0.2mm, and was not annealed after the final drawing process.

[0031] (Sample N9): "Low-purity drawn material φ2.0 (unannealed)" This is a drawn material φ2.0 mm with a magnesium purity of 99.9669% or less. Specifically, an ingot with a magnesium purity of 99.9% was extruded and drawn to a diameter of φ2.0 mm, with annealing performed midway through each stage. No annealing was performed after the final drawing.

[0032] The distribution of KAM values ​​for (Sample N1) to (Sample N9) will be described below. The KAM maps on the left side of Figures 3 to 11 show the distribution of KAM values ​​in region 12 of each sample. Crystals with KAM values ​​of 0° or more and less than 1° are shown in white, crystals with KAM values ​​of 1° or more and less than 2° are shown in gray, and crystals with KAM values ​​of 2° or more and less than 5° are shown in black. In the KAM maps of Figures 3 to 11, the A1 direction indicates the radial direction in region 12, and the A2 direction indicates the tangential direction of the outer surface in region 12. That is, the upper part of the figure shows the distribution near the center of the magnesium wire, and the lower part shows the distribution near the outer surface of the magnesium wire. Note that the KAM maps for (Sample 1) to (Sample 9) include results of measurements of different areas, but in Figures 3 to 11, each KAM map is illustrated to be approximately the same size. In addition, in Figures 3 to 11, the percentage of crystal grains with KAM values ​​of 0° or more and less than 1°, the percentage of crystal grains with KAM values ​​of 1° or more and less than 2°, and the percentage of crystal grains with KAM values ​​of 2° or more and less than 5° are shown numerically on the right side of the KAM maps.

[0033] As shown in Figure 3, the distribution of the KAM values ​​of (sample N1) was measured to be 99.7% for crystal grains with a KAM value of 0° or more and less than 1°, 0.1% for crystal grains with a KAM value of 1° or more and less than 2°, and 0.1% for crystal grains with a KAM value of 2° or more and less than 5°.

[0034] As shown in Figure 4, the distribution of the KAM values ​​of (sample N2) was measured to be 88.8% for crystal grains with a KAM value of 0° or more and less than 1°, 8% for crystal grains with a KAM value of 1° or more and less than 2°, and 3.2% for crystal grains with a KAM value of 2° or more and less than 5°.

[0035] As shown in Figure 5, the distribution of the KAM values ​​of (sample N3) was measured to be 89.3% for crystal grains with a KAM value of 0° or more and less than 1°, 7.8% for crystal grains with a KAM value of 1° or more and less than 2°, and 2.9% for crystal grains with a KAM value of 2° or more and less than 5°.

[0036] As shown in Figure 6, the distribution of the KAM values ​​of (sample N4) was measured to be 94.5% for crystal grains with a KAM value of 0° or more and less than 1°, 3.5% for crystal grains with a KAM value of 1° or more and less than 2°, and 2.0% for crystal grains with a KAM value of 2° or more and less than 5°.

[0037] As shown in FIG. 7, the distribution of the KAM values ​​of (sample N5) was measured to be 98.3% for crystal grains with a KAM value of 0° or more and less than 1°, 0.9% for crystal grains with a KAM value of 1° or more and less than 2°, and 0.8% for crystal grains with a KAM value of 2° or more and less than 5°.

[0038] As shown in Figure 8, the distribution of the KAM values ​​of (sample N6) was measured to be 98.5% for crystal grains with a KAM value of 0° or more and less than 1°, 0.6% for crystal grains with a KAM value of 1° or more and less than 2°, and 0.9% for crystal grains with a KAM value of 2° or more and less than 5°.

[0039] As shown in Figure 9, the distribution of the KAM values ​​of (sample N7) was measured to be 98.3% for crystal grains with a KAM value of 0° or more and less than 1°, 0.9% for crystal grains with a KAM value of 1° or more and less than 2°, and 0.7% for crystal grains with a KAM value of 2° or more and less than 5°.

[0040] As shown in Figure 10, the distribution of the KAM values ​​of (sample N8) was measured to be 67.1% for crystal grains with a KAM value of 0° or more and less than 1°, 13.8% for crystal grains with a KAM value of 1° or more and less than 2°, and 19.2% for crystal grains with a KAM value of 2° or more and less than 5°.

[0041] As shown in Figure 11, the distribution of the KAM values ​​of (sample N9) was measured to be 22.7% for crystal grains with a KAM value of 0° or more and less than 1°, 33.9% for crystal grains with a KAM value of 1° or more and less than 2°, and 43.3% for crystal grains with a KAM value of 2° or more and less than 5°.

[0042] (Flexibility Evaluation Test) In this embodiment, an evaluation test of the flexibility (ease of plastic deformation) of the magnesium wire was carried out for (Sample N4) and (Sample N8). In the evaluation test, the magnesium wires of (Sample N4) and (Sample N8) were wound around a bobbin having a diameter of 35 mm, left to stand for 15 hours, and then the shape of the wires when removed from the bobbin was examined.

[0043] As a result, it was found that (Sample N4) underwent uniform plastic deformation along the bobbin, and the winding tendency was formed into a uniform, neat spiral, as shown in Figure 12. In contrast, it was found that (Sample N8) did not have a uniform winding tendency, and did not form a neat spiral, as shown in Figure 13. In this embodiment, the evaluation result for a sample that formed a neat spiral, like (Sample N4), was deemed good (◯), and the evaluation result for a sample that did not form a neat spiral, like (Sample N8), was deemed bad (X).

[0044] As mentioned above, the KAM value distribution of (Sample N4) shows that 94.8% of the crystal grains have a KAM value of 0° or more but less than 1°, and the residual strain within the crystals is extremely small, making it a flexible material that is prone to plastic deformation. In contrast, the KAM value distribution of (Sample N8) shows that 67.9% of the crystal grains have a KAM value of 0° or more but less than 1°, and the residual strain within the crystals is relatively large, making it a material that lacks flexibility and is difficult to plastically deform.

[0045] As described above, the evaluation results of the flexibility of (Sample N4) and (Sample N8) show that the flexibility of magnesium wire is largely influenced by the distribution of KAM values ​​within the crystals that make up the magnesium wire (the amount of residual strain within the crystals that make up the magnesium wire).

[0046] Therefore, the inventors of the present invention have discovered that, with regard to the distribution of KAM values ​​within magnesium crystals, when the proportion of KAM values ​​between 0° and 1° is high, the residual strain within the crystal is extremely small, resulting in a material that is flexible and prone to plastic deformation, and when the proportion of KAM values ​​between 0° and 1° is low, the residual strain within the crystal is large, resulting in a material that lacks flexibility and is difficult to plastically deform.

[0047] Therefore, based on the above findings, it is possible to predict whether the flexibility of the magnesium wire is good (◯) or not (×) for samples other than (Sample N4) and (Sample N8) based on the proportion of crystal grains having a KAM value of 0° or more and less than 1°.

[0048] That is, in the distribution of KAM values ​​for (Sample N1) to (Sample N7), the proportion of crystal grains with KAM values ​​of 0° or more and less than 1° is large, at approximately 90%, or 90% or more, while in the distribution of KAM values ​​for (Sample N8) to (Sample N9), the proportion of crystal grains with KAM values ​​of 0° or more and less than 1° is smaller than 70%. As described above, the flexibility of (Sample N4) is good (◯), and the flexibility of (Sample N1) to (Sample N3) and (Sample N5) to (Sample N7) is also predicted to be good (◯). In contrast, the flexibility of (Sample N8) is poor (×), and the flexibility of (Sample N9) is also predicted to be poor (×).

[0049] (Evaluation Test of Stitch Size) In this embodiment, an evaluation test of the stitch size of the magnesium wire was conducted for (Sample N4) and (Sample N8). In the evaluation test, the magnesium wires of (Sample N4) and (Sample N8) were flat-knitted and photographed with a camera to examine the stitch size.

[0050] As a result, it was found that the size of one stitch (the length in the left-right direction in FIG. 14) of (Sample N4) when plain knitted was approximately 1 mm, as shown in FIG. 14. In contrast, it was found that the size of one stitch (the length in the left-right direction in FIG. 15) of (Sample N8) when plain knitted was approximately 3 mm, as shown in FIG. 15. In this embodiment, the evaluation result for cases where small stitches can be knitted, such as (Sample N4), is considered good (◯), and the evaluation result for cases where small stitches cannot be knitted, such as (Sample N8), is considered bad (X).

[0051] Here, the distribution of KAM values ​​for (Sample N4) shows that the proportion of crystal grains with a KAM value of 0° or more and less than 1° is 94.8%, making it a flexible material that is prone to plastic deformation, and it is thought that the evaluation result obtained was that small stitches could be knitted.In contrast, the distribution of KAM values ​​for (Sample N8) shows that the proportion of crystal grains with a KAM value of 0° or more and less than 1° is 67.9%, making it a material that is lacking in flexibility and is difficult to plastically deform, and it is thought that the evaluation result obtained was that small stitches could not be knitted.

[0052] Thus, from the evaluation results of the stitch size of (Sample N4) and (Sample N8), it can be seen that the size of a stitch when magnesium wire is flat knitted is largely influenced by the distribution of KAM values ​​within the crystals that make up the magnesium wire (the amount of residual strain within the crystals that make up the magnesium wire).

[0053] Therefore, the inventors of the present invention discovered that, regarding the distribution of KAM values ​​within magnesium crystals, when the proportion of KAM values ​​between 0° and 1° is high, the material can be woven with small stitches, and when the proportion of KAM values ​​between 0° and 1° is low, the material cannot be woven with small stitches.

[0054] Therefore, based on the above findings, it is possible to predict whether the size of a single stitch of a magnesium wire when flat knitting samples other than (Sample N4) and (Sample N8) is good (◯) or not (×) based on the proportion of crystal grains with a KAM value of 0° or more and less than 1°.

[0055] That is, in the distribution of KAM values ​​for (Sample N1) to (Sample N7), the proportion of crystal grains with KAM values ​​of 0° or more and less than 1° is large, at approximately 90%, or 90% or more, while in the distribution of KAM values ​​for (Sample N8) to (Sample N9), the proportion of crystal grains with KAM values ​​of 0° or more and less than 1° is less than 70%. The evaluation result of the stitch size for (Sample N4) is good (◯), and similarly, the evaluation results of the stitch size for (Sample N1) to (Sample N3) and (Sample N5) to (Sample N7) are also predicted to be good (◯). In contrast, the evaluation result of the stitch size for (Sample N8) is poor (×), and similarly, the evaluation result of the stitch size for (Sample N9) is also predicted to be poor (×).

[0056] The distribution of KAM values ​​and the evaluation results of flexibility for (Sample N1) to (Sample N9) are summarized in FIG.

[0057] Considering the results in Figure 16, it can be seen that (Sample N2) was obtained by repeatedly drawing the φ3.0 mm extruded material of (Sample N1) without annealing in between each stage, and that even in the stage of (Sample N1), which is the extruded material before drawing, the proportion of crystal grains with a KAM value of 0° or more and less than 1° was as high as 99.7%, and even in the φ2.0 mm drawn material of (Sample N2) after drawing, the proportion of crystal grains with a KAM value of 0° or more and less than 1° was 88.8%, which does not change significantly. Similarly, (Sample N4) was obtained by repeatedly drawing the φ1.0 mm drawn material of (Sample N3) without annealing at each stage, but it can be seen that the proportion of crystal grains with a KAM value of 0° or more and less than 1° was high at 89.3% in the stage of (Sample N3), which is the drawn material before drawing, and even in the φ0.2 mm drawn material of (Sample N4) after drawing, the proportion of crystal grains with a KAM value of 0° or more and less than 1° was 94.8%, which does not change significantly. According to the results of (Sample N2) to (Sample N4), the proportion of crystal grains with a KAM value of 0° or more and less than 1° increases by repeatedly drawing until the diameter of the magnesium wire becomes thinner.

[0058] In addition, in (Sample N1), the magnesium purity is 99.995% or more, and there are few impurities at the grain boundaries between the magnesium crystal grains. Magnesium crystal grains have the property of moving and aligning in the same direction when subjected to processing pressure, but it is presumed that if there are few impurities at the grain boundaries between the magnesium crystal grains, the crystal grains will move more easily, resulting in a smaller KAM value (misorientation). In contrast, in (Sample N8) and (Sample N9), the magnesium purity is 99.9669% or less, and both are low in purity, so it is presumed that impurities at the grain boundaries between the magnesium crystal grains hinder the movement of the magnesium crystal grains, resulting in a larger KAM value (misorientation).

[0059] In contrast, when there are few impurities at the grain boundaries between magnesium crystal grains, as in (Sample N1) and (Sample N3), the magnesium that makes up the grain boundaries is more likely to align (crystallize) at the atomic level, which is thought to cause the crystal grains to coalesce (fuse) together, preventing them from becoming smaller. As a result, when drawing materials with a magnesium purity of 99.995% or higher, it is thought that repeated drawing can be performed without annealing between each stage.

[0060] In contrast, when there are many impurities at the grain boundaries between magnesium crystal grains, as in (Sample N8) and (Sample N9), the impurities make it difficult for the magnesium at the grain boundaries to align (crystallize) at the atomic level. Repeated drawing increases the number of grain boundaries, leading to finer magnesium crystal grains. As a result, the KAM value increases, suggesting work hardening. Therefore, while the proportion of grains with a KAM value of 0° or greater but less than 1° in (Sample N9) is low at approximately 22%, the proportion of grains with a KAM value of 0° or greater but less than 1° increases to approximately 98% in (Sample N5) to (Sample N7) after annealing (Sample N9) at 250°C for 30, 60, or 120 minutes, resulting in high flexibility.

[0061] The magnesium wire of this embodiment is made of high-purity magnesium containing magnesium as a main component, or a magnesium alloy containing magnesium as a main component. High-purity magnesium contains 99% by mass or more of Mg, with the remainder consisting of impurities. The impurities include unavoidable elements. Examples of impurities include Al, Si, Mn, Fe, Zn, Zr, Cu, Ni, Cr, and Ca. For medical magnesium wire, it is desirable to increase the purity of the magnesium and eliminate or reduce the impurities to an unavoidable level. It is particularly preferable to eliminate elemental components that are unsafe for living organisms. Furthermore, in the case of a magnesium alloy, the main component is less than 99% by mass of Mg, to which various elements, such as Al, Si, Mn, Fe, Zn, Zr, Cu, Ni, Cr, and Ca, or compounds thereof, are added.

[0062] The magnesium wire according to this embodiment is a thin wire, but is braided into a sheet or string and used as a medical device (for example, a device used for suturing an incision). In this case, if the magnesium wire has a high proportion of crystal grains with a KAM value of less than 1°, when it is deformed into a certain shape, it will deform easily to that shape, and the shape when braided into a sheet or string will be uniform and very easy to use. In contrast, if the magnesium wire has a low proportion of crystal grains with a KAM value of 0° or more but less than 1°, even if it is deformed into a certain shape, the shape after deformation will be distorted, and when braided into a sheet or string, it will not be uniform and will be difficult to use.

[0063] As described above, the magnesium wire of the present embodiment is a magnesium wire containing magnesium as its main component, and the proportion of crystal grains constituting the magnesium wire whose KAM value is 0° or more and less than 1° is 70% or more.

[0064] This makes it possible to obtain a magnesium wire that is highly flexible and difficult to break even when subjected to complex shape deformation.

[0065] The method for manufacturing magnesium wire of this embodiment is a method for manufacturing magnesium wire that is thinned by repeatedly performing drawing or extrusion, and produces magnesium wire in which the proportion of crystal grains with a KAM value of 0° or more and less than 1° is 70% or more without performing annealing treatment in each drawing or extrusion process.

[0066] This makes it possible to obtain a magnesium wire that is highly flexible and difficult to break even when complex shape deformation is involved, without performing an annealing treatment in each step of the drawing or extrusion process.

[0067] The magnesium wire evaluation method according to this embodiment is a method for evaluating the flexibility of a magnesium wire whose main component is magnesium, and evaluates the flexibility based on the proportion of crystal grains that have a KAM value of 0° or more and less than 1° among the crystal grains that make up the magnesium wire.

[0068] This allows a new evaluation method that has not been available before, that is, an accurate evaluation of the flexibility of magnesium wire based on the proportion of crystal grains whose KAM value is less than a predetermined value.

[0069] Although the embodiment of the present invention has been described above, the configuration of the embodiment is not limited to the above, and various modifications are possible.

[0070] For example, in the above embodiment, the magnesium wire samples are described as having diameters of φ3.0, φ2.0, φ1.0, and φ0.2, but the diameter of the magnesium wire is not limited thereto. The diameter of the magnesium wire of the present invention is arbitrary.

[0071] In the above embodiment, the flexibility and mesh size of the magnesium wire are evaluated based on the proportion of crystal grains that make up the magnesium wire and have a KAM value of 0° or more and less than 1°, but this is not limiting. The flexibility and mesh size of the magnesium wire may also be evaluated based on the proportion of crystal grains that make up the magnesium wire and have a KAM value of 0° or more and less than a predetermined value. The predetermined value can be set arbitrarily. Therefore, for example, the flexibility and mesh size of the magnesium wire may also be evaluated based on the proportion of crystal grains that make up the magnesium wire and have a KAM value of 0° or more and less than 2°.

[0072] In the above embodiments, the extruded material, the drawn material, and the drawn material that has been annealed have been described, but the present invention is not limited thereto. The present invention is applicable to a magnesium wire that has been thinned by repeatedly performing drawing or extrusion.

[0073] Other configurations can also be modified in various ways without departing from the spirit of the present invention.

[0074] The present invention can be used as a magnesium wire containing magnesium as a main component, a method for manufacturing a magnesium wire, and a method for evaluating a magnesium wire.

[0075] 1. Magnesium wire

Claims

1. A magnesium wire containing magnesium as its main component, characterized in that the proportion of crystal grains constituting the magnesium wire having a KAM value of 0° or more and less than 1° is 70% or more.

2. A method for manufacturing magnesium wire thinned by repeated drawing or extrusion processing, characterized in that magnesium wire is manufactured in which the proportion of crystal grains having a KAM value of 0° or more and less than 1° is 70% or more without performing annealing treatment in each drawing or extrusion process.

3. A method for evaluating the flexibility of a magnesium wire whose main component is magnesium, characterized in that the evaluation is based on the proportion of crystal grains that make up the magnesium wire and have a KAM value of 0° or more and less than a specified value.

Images