Stainless steel wire in as-drawn state, heat-treated stainless steel wire, and wire for stainless steel wire

Abstract

Provided is a stainless steel wire in an as-drawn state comprising, in mass%, 0.01-0.20% C, 0.1-4.0% Si, 0.1-10.0% Mn, 2.0-15.0% Ni, 17.0-25.0% Cr, 0.1-4.0% Mo, 0.10-0.50% N, and 0.5-4.0% Cu, wherein a value A expressed by expression (a) is not more than -60, the dislocation density of an austenite phase of the wire is 1×1015 / m2 to 100×1015 / m2, and the processing-induced martensite amount 50 μm from the wire surface layer is not more than 50%. Also provided is a heat-treated stainless steel wire comprising similar components, wherein a recrystallization ratio is not less than 0.80, and crystal grain size in the surface layer is not more than 80 μm.

Description

Stainless steel wire as-drawn, stainless steel wire after heat treatment, and wire rods for stainless steel wire.

[0001] This invention relates to stainless steel wire as drawn, stainless steel wire after heat treatment, and wire materials for stainless steel wire.

[0002] Conventionally, stainless steel wire products such as ropes, springs, and wire mesh have been manufactured by processing and shaping austenitic stainless steel wire or steel wire, such as SUS304 and SUS316, and then subjecting them to high-temperature heat treatment to ensure ductility. Examples of austenitic stainless steel wire or steel wire for such stainless steel wire products include those listed in Patent Documents 1 to 3.

[0003] The invention described in Patent Document 1 is an inexpensive method for manufacturing highly ductile fine wires, which allows for control of γ stability by adjusting the component composition, strong drawing of 80% or more down to φ300 μm or less, and ultra-short-time strand annealing after wire drawing.

[0004] The invention described in Patent Document 2 is a wire material for ultra-fine wires in which inclusions are controlled by reducing the Al content and performing a special melting process in a vacuum, and the composition is controlled to C > 3N in order to improve wire drawability. It is possible to draw wires down to ultra-fine wires, and high strength and high ductility are imparted by annealing after drawing.

[0005] The invention described in Patent Document 3 is a SUS304 ultrafine wire containing 0.1 to 0.5% N, in which the austenite structure is refined to a predetermined particle size or higher by wire drawing and heat treatment, thereby achieving the target yield strength and elongation values.

[0006] Patent No. 4098171 Patent No. 6491983 Patent No. 4068216

[0007] When manufacturing stainless steel wire products such as ropes, springs, and wire mesh, stainless steel wire rods are first produced by hot rolling cast slabs. These stainless steel wire rods are then cold-drawn to produce stainless steel wire before heat treatment, and finally, the stainless steel wire before heat treatment is subjected to heat treatment to produce stainless steel wire after heat treatment. Hereinafter, stainless steel wire before heat treatment will be referred to as "as-drawn stainless steel wire," and stainless steel wire after heat treatment will be referred to as "heat-treated stainless steel wire." When referring to both, the term "stainless steel wire" will be used.

[0008] For example, in the manufacture of ropes and springs, stainless steel wire in its drawn state before heat treatment is used to perform the required product processing, resulting in a product that meets the final quality standards of stainless steel wire. After product processing, annealing or aging heat treatment is performed as needed. Similarly, in the manufacture of wire mesh, stainless steel wire that has undergone heat treatment is used to perform the required product processing, resulting in a product that meets the final quality standards of stainless steel wire.

[0009] As described above, in order to process products using stainless steel wire as-drawn and stainless steel wire after heat treatment, both stainless steel wire as-drawn and stainless steel wire after heat treatment must possess the necessary strength and ductility.

[0010] The present invention aims to provide stainless steel wire as-drawn, stainless steel wire after heat treatment, and stainless steel wire materials that exhibit excellent strength and ductility.

[0011] In other words, the gist of the present invention is as follows: [1] Contains, by mass%, C: 0.010 to 0.20%, Si: 0.1 to 4.0%, Mn: 0.1 to 10.0%, Ni: 2.0 to 15.0%, Cr: 17.0 to 25.0%, Mo: 0.1 to 4.0%, N: 0.10 to 0.50%, Cu: 0.5 to 4.0%, The composition is V: 0-2.5%, B: 0-0.012%, Al: 0-2.0%, W: 0-2.5%, Ga: 0-0.0500%, Co: 0-2.5%, Sn: 0-2.5%, Ti: 0-1.0%, Nb: 0-2.5%, Ta: 0-2.5%, Ca: 0-0.012%, Mg: 0-0.012%, Zr: 0-0.012%, REM: 0-0.05%, with the remainder being Fe and impurities. The A value shown in the following formula (a) is -60 or less. It has a metallic structure mainly composed of an austenite phase, and the dislocation density of the austenite phase in the steel wire is 1 × 10⁻⁶. １５ / m ２ ~100 x 10 １５ / m ２ Stainless steel wire as-drawn, wherein the amount of work-induced martensite in the top 50 μm of the steel wire surface is 50% or less. A value = 551 - 462 (C + N) - 9.2 Si - 8.1 Mn - 29 (Ni + Cu) - 13.7 Cr - 18.5 Mo ... (a) However, the element symbols in the formula represent the content (mass %) of the element in the steel. Also, if the content of an element in formula (a) is 0%, "0" is substituted in place of the corresponding symbol in the calculation. [2] The stainless steel as-drawn wire according to [1], further containing, by mass%, one or more selected from V: 0.001 to 2.5%, B: 0.001 to 0.012%, Al: 0.001 to 2.0%, W: 0.05 to 2.5%, Ga: 0.0004 to 0.0500%, Co: 0.05 to 2.5%, Sn: 0.01 to 2.5%, Ti: 0.01 to 1.0%, Nb: 0.01 to 2.5%, Ta: 0.01 to 2.5%, Ca: 0.0002 to 0.012%, Mg: 0.0002 to 0.012%, Zr: 0.0002 to 0.012%, and REM: 0.0002 to 0.05%. [3] Stainless steel wire as drawn according to [1] or [2], wherein the tensile strength is 1700 to 4500 MPa, the reduction of area at break is 10% or more, and the twist value (100d) is 1 or more.

[0012] [4] Contains, by mass%, C: 0.010-0.20%, Si: 0.1-4.0%, Mn: 0.1-10.0%, Ni: 2.0-15.0%, Cr: 17.0-25.0%, Mo: 0.1-4.0%, N: 0.10-0.50%, Cu: 0.5-4.0%, Stainless steel wire after heat treatment, wherein the composition is V: 0-2.5%, B: 0-0.012%, Al: 0-2.0%, W: 0-2.5%, Ga: 0-0.0500%, Co: 0-2.5%, Sn: 0-2.5%, Ti: 0-1.0%, Nb: 0-2.5%, Ta: 0-2.5%, Ca: 0-0.012%, Mg: 0-0.012%, Zr: 0-0.012%, REM: 0-0.05%, with the remainder being Fe and impurities, the A value shown in the following formula (a) is -60 or less, the recrystallization rate of the 50 μm surface layer of the steel wire is 0.80 or more, and the grain size of the 50 μm surface layer of the steel wire is 80 μm or less. A value = 551 - 462 (C + N) - 9.2 Si - 8.1 Mn - 29 (Ni + Cu) - 13.7 Cr - 18.5 Mo ... (a) However, the element symbols in the formula represent the content (mass %) of the element in the steel. Also, if the content of an element in formula (a) is 0%, substitute "0" in the place of the corresponding symbol in the calculation. [5] The stainless steel heat-treated wire according to [4], further containing, by mass%, one or more selected from V: 0.001 to 2.5%, B: 0.001 to 0.012%, Al: 0.001 to 2.0%, W: 0.05 to 2.5%, Ga: 0.0004 to 0.0500%, Co: 0.05 to 2.5%, Sn: 0.01 to 2.5%, Ti: 0.01 to 1.0%, Nb: 0.01 to 2.5%, Ta: 0.01 to 2.5%, Ca: 0.0002 to 0.012%, Mg: 0.0002 to 0.012%, Zr: 0.0002 to 0.012%, and REM: 0.0002 to 0.05%. [6] Stainless steel wire after heat treatment according to [4] or [5], wherein the tensile strength is 600 to 1200 MPa, the reduction of area at break is 40% or more, and the pitting potential is 0.20 V or more.

[0013] [7] Contains, by mass%, C: 0.010-0.20%, Si: 0.1-4.0%, Mn: 0.1-10.0%, Ni: 2.0-15.0%, Cr: 17.0-25.0%, Mo: 0.1-4.0%, N: 0.10-0.50%, Cu: 0.5-4.0%, A wire material for stainless steel wire, comprising V: 0-2.5%, B: 0-0.012%, Al: 0-2.0%, W: 0-2.5%, Ga: 0-0.0500%, Co: 0-2.5%, Sn: 0-2.5%, Ti: 0-1.0%, Nb: 0-2.5%, Ta: 0-2.5%, Ca: 0-0.012%, Mg: 0-0.012%, Zr: 0-0.012%, REM: 0-0.05%, with the remainder being Fe and impurities, and having an A value of -60 or less as shown in the following formula (a). A value = 551 - 462 (C + N) - 9.2 Si - 8.1 Mn - 29 (Ni + Cu) - 13.7 Cr - 18.5 Mo ... (a) However, the element symbols in formula (a) represent the content (mass %) of the element in the steel. Also, if the content of an element in formula (a) is 0%, "0" is substituted in place of the corresponding symbol in the calculation. [8] The wire material for stainless steel wire according to [7], further containing, by mass%, one or more selected from V: 0.001 to 2.5%, B: 0.001 to 0.012%, Al: 0.001 to 2.0%, W: 0.05 to 2.5%, Ga: 0.0004 to 0.0500%, Co: 0.05 to 2.5%, Sn: 0.01 to 2.5%, Ti: 0.01 to 1.0%, Nb: 0.01 to 2.5%, Ta: 0.01 to 2.5%, Ca: 0.0002 to 0.012%, Mg: 0.0002 to 0.012%, Zr: 0.0002 to 0.012%, and REM: 0.0002 to 0.05%.

[0014] According to one aspect of the present invention, stainless steel wire as drawn and stainless steel wire after heat treatment can be realized, both of which exhibit excellent strength and ductility.

[0015] The stainless steel material according to this embodiment (as-drawn stainless steel wire, heat-treated stainless steel wire, and wire rod for stainless steel wire) contains, by mass%, C: 0.010 to 0.20%, Si: 0.1 to 4.0%, Mn: 0.1 to 10.0%, Ni: 2.0 to 15.0%, Cr: 17.0 to 25.0%, Mo: 0.1 to 4.0%, N: 0.10 to 0.50%, Cu: 0.5 to 4.0%, and V: The composition is as follows: 0-2.5%, B: 0-0.012%, Al: 0-2.0%, W: 0-2.5%, Ga: 0-0.0500%, Co: 0-2.5%, Sn: 0-2.5%, Ti: 0-1.0%, Nb: 0-2.5%, Ta: 0-2.5%, Ca: 0-0.012%, Mg: 0-0.012%, Zr: 0-0.012%, REM: 0-0.05%, with the remainder being Fe and impurities. In other words, the stainless steel material according to this embodiment is a so-called austenitic stainless steel, whose microstructure at room temperature is mainly composed of the austenite phase. The microstructure of the stainless steel material according to this embodiment contains 95% or more of the austenite phase, and may also contain trace amounts of other materials such as ferrite, precipitates, and inclusions.

[0016] Chemical Composition of Stainless Steel Wire Rods (As-Drawn, Heat-Treated, and Stainless Steel Wire) Below, we will first explain the chemical composition of stainless steel wire rods (as-drawn, heat-treated, and stainless steel wire). The "%" in the chemical composition of steel refers to mass percent. Numerical ranges expressed using "~" mean the range that includes the numbers before and after "~" as the lower and upper limits, respectively. Note that if "greater than" or "less than" is attached to the numbers before or after "~", the numerical range means the range that does not include those numbers as the lower or upper limit, respectively.

[0017] (C: 0.010-0.20%) C is added at a concentration of 0.010% or more to ensure the strength of the steel wire after drawing. Preferably, it is 0.04% or more, and more preferably 0.06% or more. However, if added at a concentration exceeding 0.20%, the strength becomes too high and the reduction at fracture decreases. Therefore, the upper limit of C is set at 0.20%. Preferably, it is 0.15% or less, and more preferably 0.09% or less. For example, a preferred range for C is 0.04-0.15%, and a more preferred range is 0.06-0.09%.

[0018] (Si: 0.1-4.0%) Si is added at a concentration of 0.1% or more to ensure deoxidation and strength. Preferably, it is 0.2% or more, and more preferably 0.3% or more. However, if Si is added at a concentration exceeding 4.0%, the reduction at fracture decreases, so the upper limit is set at 4.0%. Preferably, it is 2.0% or less, and more preferably 1.0% or less. For example, the preferred range for Si is 0.2-2.0%, and the more preferred range is 0.2-1.0%.

[0019] (Mn: 0.1-10.0%) Mn is added at a concentration of 0.1% or more to ensure austenite stability and strength. Preferably, it is 1.0% or more, and more preferably 1.5% or more. However, adding more than 10.0% Mn reduces the reduction at fracture, so the upper limit is set at 10.0%. Preferably, it is 5.0% or less, and more preferably 3.0% or less. For example, the preferred range for Mn is 1.0-5.0%, and the more preferred range is 1.5-3.0%.

[0020] (Ni: 2.0-15.0%) Ni is added at a concentration of 2.0% or more to ensure austenite stability and ductility. Preferably, it is 5.0% or more, and more preferably 6.0% or more. However, adding more than 15.0% increases the alloy cost and reduces the strength of the stainless steel wire, so the upper limit is set at 15.0%. Preferably, it is 9.0% or less, and more preferably 8.0% or less. For example, the preferred range for Ni is 5.0-9.0%, and the more preferred range is 6.0-8.0%.

[0021] (Cr: 17.0-25.0%) Cr is added at a concentration of 17.0% or more to ensure corrosion resistance and nitrogen solubility. Preferably, it is 18.0% or more, and more preferably 18.5% or more. However, adding more than 25.0% reduces the reduction at fracture, so the upper limit is set at 25.0%. Preferably, it is 23.0% or less, and more preferably 22.0% or less. For example, the preferred range for Cr is 18.0-23.0%, and the more preferred range is 18.5-22.0%.

[0022] (Mo: 0.1-4.0%) Mo is added at a concentration of 0.1% or more to improve the corrosion resistance of the stainless steel wire. Preferably, it is 0.2% or more, and more preferably 0.3% or more. However, adding more than 4.0% increases the alloy cost and reduces the reduction at fracture, so the upper limit is set at 4.0%. Preferably, it is 2.0% or less, and more preferably 1.0% or less. For example, the preferred range for Mo is 0.1-2.0%, and the more preferred range is 0.1-1.0%.

[0023] (N: 0.10-0.50%) N is set to 0.10% or more to ensure strength and corrosion resistance. Preferably it is 0.15% or more, and more preferably 0.20% or more. However, if it exceeds 0.50%, the strength decreases and the reduction at fracture decreases, so the upper limit is set to 0.50%. Preferably it is 0.40% or less, and more preferably 0.30% or less. For example, the preferred range for N is 0.15-0.40%, and the more preferred range is 0.15-0.30%.

[0024] (Cu: 0.5-4.0%) Cu is added at a concentration of 0.5% or more to ensure ductility and austenite stability. Preferably, it is 0.8% or more, and more preferably 1.4% or more. However, adding more than 4.0% can cause hot working cracks and reduce strength, so the upper limit is set at 4.0%. Preferably, it is 3.5% or less. For example, the preferred range for Cu is 0.8-3.5%, and the more preferred range is 1.4-3.5%.

[0025] By adding N and Cu in the manner described above, the dislocation density of the austenite phase in the as-drawn stainless steel wire can be reduced, thereby ensuring a balance between strength and ductility in the as-drawn stainless steel wire. Furthermore, by adding N and Cu in the manner described above, the formation of work-induced martensite in the heat-treated stainless steel wire can be suppressed, thereby ensuring a balance between strength and ductility in the heat-treated stainless steel wire.

[0026] The stainless steel wire and wire rod for stainless steel wire of the present invention contain the above components, with the remainder being Fe and impurities. Here, impurities refer to elements that are mixed in from raw materials such as ore, scrap, or the manufacturing environment during the industrial production of steel materials that serve as the base material for steel profiles, and are not intentionally included in the steel profiles. Examples of impurities include P, S, and O. The impurities may be present in amounts of 0.050% or less of P, 0.030% or less of S, and 0.020% or less of O.

[0027] (Regarding optional elements) The chemical composition of the stainless steel wire as drawn in this embodiment may further be selectively modified by adding one or more of the following elements. These elements are all optional and may not be added.

[0028] (V: 0-2.5%) V may be added as needed to improve the strength-ductility balance. However, adding more than 2.5% will conversely decrease the strength-ductility balance, so the upper limit should be 2.5%. Preferably it is 1.0% or less, more preferably 0.7% or less, and even more preferably 0.5% or less. The above effects can be achieved if the V content is 0.001% or more.

[0029] (B: 0-0.012%) B may be added as needed to improve the strength-ductility balance. However, adding more than 0.012% will actually decrease the strength-ductility balance, so the upper limit should be 0.012%. The above effects can be achieved if the B content is 0.001% or more.

[0030] (Al: 0-2.0%) Al may be added as needed to improve the balance of strength and ductility. However, adding more than 2.0% will conversely decrease the balance of strength and ductility, so the upper limit should be 2.0%. Preferably, it should be 1.0% or less, more preferably 0.5% or less, and even more preferably 0.05% or less. The above effects can be achieved if the Al content is 0.001% or more.

[0031] (W: 0-2.5%) W may be added as needed to improve the corrosion resistance of the stainless steel wire. However, adding more than 2.5% will degrade the drawability, so the upper limit should be 2.5%. More preferably, it should be 2.0% or less, and even more preferably 1.5% or less. The above effects can be achieved if the W content is 0.05% or more.

[0032] (Ga: 0-0.0500%) Ga may be added as needed to improve corrosion resistance. However, adding more than 0.0500% will degrade the wire drawability, so the upper limit should be 0.0500%. The above effects can be achieved if the Ga content is 0.0004% or higher.

[0033] (Co: 0-2.5%) Co may be added as needed to improve corrosion resistance. However, adding more than 2.5% will degrade the wire drawability, so the upper limit should be 2.5%. More preferably, it should be 1.0% or less, and even more preferably 0.8% or less. The above effects can be achieved if the Co content is 0.05% or more.

[0034] (Sn: 0-2.5%) Sn may be added as needed to improve corrosion resistance. However, adding more than 2.5% will degrade the wire drawability, so the upper limit should be 2.5%. More preferably, it should be 1.0% or less, and even more preferably 0.2% or less. The above effects can be achieved if the Sn content is 0.01% or more.

[0035] (Ti: 0-1.0%) Ti may be added as needed to improve the strength-ductility balance. However, adding more than 1.0% will conversely decrease the strength-ductility balance, so the upper limit should be 1.0%. Preferably it should be 0.7% or less, and more preferably 0.5% or less. The above effects can be achieved if the Ti content is 0.01% or more.

[0036] (Nb: 0-2.5%) Nb may be added as needed to improve the strength-ductility balance. However, adding more than 2.5% will conversely decrease the strength-ductility balance, so the upper limit should be 2.5%. Preferably it is 1.0% or less, more preferably 0.7% or less, and even more preferably 0.5% or less. The above effects can be achieved if the Nb content is 0.01% or more.

[0037] (Ta: 0-2.5%) Ta may be added as needed to improve the strength-ductility balance. However, adding more than 2.5% will conversely decrease the strength-ductility balance, so the upper limit should be 2.5%. Preferably it is 1.0% or less, more preferably 0.7% or less, and even more preferably 0.5% or less. The above effects can be achieved if the Ta content is 0.01% or more.

[0038] (Ca: 0-0.012%) Ca may be added as needed for deoxidation. However, adding more than 0.012% will degrade the wire drawability, so the upper limit should be 0.012%. The Ca content is preferably 0.010% or less, and more preferably 0.005% or less. The above effects can be achieved if the Ca content is 0.0002% or more.

[0039] (Mg: 0-0.012%) Mg may be added as needed for deoxidation. However, adding more than 0.012% will degrade the wire drawability, so the upper limit should be 0.012%. Preferably it is 0.010% or less, and more preferably 0.005% or less. The above effects can be achieved if the Mg content is 0.0002% or more.

[0040] (Zr: 0-0.012%) Zr may be added as needed for deoxidation. However, adding more than 0.012% will degrade the wire drawability, so the upper limit should be 0.012%. Preferably it is 0.010% or less, and more preferably 0.005% or less. The above effects can be achieved if the Zr content is 0.0002% or more.

[0041] (REM: 0-0.05%) REM may be added as needed for deoxidation. REM (rare earth elements), according to the general definition, refers to the two elements scandium (Sc) and yttrium (Y), and the 15 elements from lanthanum (La) to lutetium (Lu) (lanthanoids). They may be included individually or in mixtures. However, since adding more than 0.05% deteriorates the wire drawability, the upper limit is set at 0.05%. Preferably it is 0.010% or less, and more preferably 0.005% or less. The above effects can be achieved if the REM content is 0.0002% or more.

[0042] (A value: -60 or less) The A value, defined by the following formula (a), is an index obtained by investigating the relationship between the volume fraction and composition of work-induced martensite after wire drawing, and it is necessary to control it in order to prevent the excessive generation of work-induced martensite in steel wire after wire drawing. If the A value exceeds -60, the work-induced martensite phase will be excessively generated during wire drawing, so the A value is limited to -60 or less. Preferably it is -100 or less, and more preferably -150 or less. In order to prevent increased costs due to high alloy content, it is preferable to set the lower limit of the A value to -400. A value = 551 - 462 (C + N) - 9.2 Si - 8.1 Mn - 29 (Ni + Cu) - 13.7 Cr - 18.5 Mo ... (a) However, the element symbols in formula (a) mean the content (mass %) of the element in the steel. Furthermore, if the element content in formula (a) is 0%, substitute "0" in the corresponding symbol and calculate.

[0043] Even though the upper limit of the Ni content is as low as 15.0%, by restricting the A value to -60 or less as described above, it becomes possible to suppress the excessive generation of the processing-induced martensite phase during wire drawing.

[0044] <<First Embodiment>> Hereinafter, the embodiment of the stainless steel wire as it is in wire drawing will be described in detail.

[0045] (Dislocation density of austenite phase: 1×10 １５ / m ２ ~100×10 １５ / m ２ ) If the dislocation density of the austenite phase of the stainless steel wire as it is in wire drawing in the first embodiment is too low, it becomes difficult to ensure strength, so the lower limit is set to 1×10 １５ / m ２ . Preferably, it is 3×10 １５ / m ２ or more. On the other hand, if the dislocation density of the austenite phase is too high, it becomes impossible to ensure the reduction in fracture, so the upper limit is set to 100×10 １５ / m ２ . Preferably, it is 50×10 １５ / m ２ or less, more preferably 30×10 １５ / m ２ or less, still more preferably 10×10 １５ / m ２ or less. For example, the preferable range of the dislocation density of the austenite phase is 3×10 １５ / m ２ ~50×10 １５ / m ２ , more preferably 3×10 １５ / m ２ ~30×10 １５ / m ２ , still more preferably 3×10 １５ / m ２ ~10×10 １５ / m ２ .

[0046] (Metal structure) The crystalline structure of the stainless steel wire in the first embodiment, as drawn, exhibits a work structure. After polishing and etching the L-section of the stainless steel wire (a section containing the central axis of the wire and parallel to the central axis), the degree of grain expansion can be observed with an optical microscope to confirm that it is a work structure. The dislocation density of the austenite phase is 1 × 10⁻⁶. １５ / m ２ From the above, it can be seen that the crystal structure is as it is in its processed state without heat treatment.

[0047] The metallic structure of the stainless steel wire as drawn in the first embodiment is mainly composed of the austenite phase. This can be confirmed by performing X-ray diffraction. If the diffraction pattern obtained from analyzing the sample by X-ray diffraction, as described later, shows a face-centered cubic lattice structure (FCC), then it can be said that the structure is mainly composed of the austenite phase.

[0048] (Amount of work-induced martensite in the 50 μm surface layer of the steel wire: 50% or less) In the as-drawn stainless steel wire of the first embodiment, a portion of the austenite is transformed into work-induced martensite by the drawing process. The amount of work-induced martensite in the 50 μm surface layer of the as-drawn stainless steel wire of the first embodiment is 50% or less. The amount of work-induced martensite in the 50 μm surface layer of the steel wire refers to the amount of work-induced martensite in a 50 × 50 μm area centered at a position 50 μm from the surface of the steel wire in an L-shaped cross section of the steel wire (a cross section including the central axis of the steel wire and parallel to the central axis).

[0049] By limiting the amount of work-induced martensite in the 50 μm surface layer of the steel wire to 50% or less, a high torsion value can be achieved in stainless steel wire as-drawn. The torsion value is obtained by a torsion test. Since the maximum stress is applied to the surface layer of the steel wire during the torsion test, the torsion value is influenced by the microstructure of the steel wire surface layer. Because work-induced martensite does not have deformability, the remaining austenite, which does have deformability, contributes to the high torsion value.

[0050] Furthermore, keeping the amount of work-induced martensite in the 50 μm surface layer of the steel wire below 50% contributes to ensuring a good recrystallization rate and optimizing the grain size of the surface layer in the heat-treated steel wire of the second embodiment described later. If the amount of work-induced martensite in the 50 μm surface layer of the stainless steel wire as-drawn exceeds 50%, recrystallization will be poor in the heat-treated stainless steel wire, resulting in a decrease in the recrystallization rate and an increase in the grain size of the surface layer.

[0051] (Tensile strength: 1700 to 4500 MPa) The stainless steel wire as drawn according to the first embodiment preferably has a tensile strength in the range of 1700 to 4500 MPa. By setting the tensile strength to 1700 MPa or higher, the high strength that is the objective of the present invention can be sufficiently achieved. On the other hand, if the tensile strength exceeds 4500 MPa, sufficient reduction of area at fracture cannot be ensured. More preferably, the tensile strength is 1800 to 3500 MPa. Even more preferably, the tensile strength is 1900 to 3000 MPa.

[0052] (Reduced size at break: 10% or more) The stainless steel wire as drawn according to the first embodiment preferably has a reduced size at break of 10% or more. By having a reduced size at break of 10% or more, a highly ductile stainless steel wire as drawn can be provided. More preferably, the reduced size at break is 20% or more, and even more preferably 30% or more.

[0053] (Twist value: 1 or more) The stainless steel wire as drawn according to the first embodiment preferably has a twist value of 1 or more. By setting the twist value to 1 or more, a highly ductile stainless steel wire as drawn can be provided. More preferably, the twist value is 5 or more, and even more preferably 10 or more.

[0054] 《Method for Manufacturing Stainless Steel Wire in the As-Drawn State of the First Embodiment》 Next, a method for manufacturing stainless steel wire in the as-drawn state according to the first embodiment will be described. It should be noted that the method for manufacturing stainless steel wire in the as-drawn state and wire material for stainless steel wire according to the present invention is not limited to the conditions described below.

[0055] Steel having the above-mentioned component composition is melted and cast into slabs of a predetermined diameter, after which hot wire rolling is performed on the slabs. Subsequently, solution treatment and pickling are performed as needed to produce wire for stainless steel wire.

[0056] The stainless steel wire as-drawn according to the first embodiment is obtained by cold drawing the stainless steel wire material described above. Specifically, a predetermined material is shot peened (SP) before drawing to form a lubricating film, and then drawn and subjected to solution heat treatment under the following conditions. The process from shot peening to solution heat treatment is repeated to obtain the desired wire diameter. The steel wire before the solution heat treatment after final drawing is the stainless steel wire as-drawn. The predetermined material before drawing refers to the wire material after hot rolling as described above, or a steel wire that has undergone preliminary drawing and intermediate strand annealing.

[0057] (Shot peening before wire drawing) Shot peening (SP) is performed on the steel wire before forming a lubricating film for wire drawing. This allows wire drawing to be performed without seizing, even when the die half-angle used in the wire drawing process described later is reduced. The shot peening conditions are, for example, SUS shot with a projection speed of 40 to 100 m / s and a projection angle of 30 to 90°.

[0058] (Half-angle of die used in wire drawing: 3° to 9°) By reducing the half-angle of the die used in wire drawing to 9° or less, the processing strain on the surface of the steel wire during wire drawing can be reduced, and the formation of processing-induced martensite on the surface can be suppressed. If the die half-angle exceeds 9°, seizing occurs during wire drawing, the surface of the steel wire is over-processed, and the formation of processing-induced martensite on the surface is promoted. On the other hand, if the die half-angle is small, seizing is more likely to occur. By performing shot peening (SP) before forming a film on the steel wire for wire drawing, wire drawing can be performed without seizing even with a small die half-angle. However, if the die half-angle is less than 3°, even if shot peening is performed, seizing cannot be prevented, and on the contrary, the surface of the steel wire is over-processed, and the formation of processing-induced martensite on the surface is promoted. The die half-angle is preferably 4 to 8°, and more preferably 4 to 6°.

[0059] (Wire diameter of stainless steel wire) The wire diameter of the stainless steel wire of the present invention can be used in the range of 0.01 to 4.0 mm. In particular, it can be preferably used in the range of 0.1 to 1.0 mm.

[0060] 《Second Embodiment》 By applying heat treatment to the stainless steel wire as it is drawn according to the first embodiment, the stainless steel wire after heat treatment according to the second embodiment described below can be obtained. This will be explained in detail below.

[0061] The stainless steel wire after heat treatment of the second embodiment can be obtained by heat-treating the stainless steel wire as drawn according to the first embodiment. The crystalline structure of the stainless steel wire after heat treatment of the second embodiment is such that the recrystallization rate of the 50 μm surface layer of the steel wire is 0.80 or more, and the grain size of the 50 μm surface layer of the steel wire is 80 μm or less. The recrystallization rate and grain size of the 50 μm surface layer of the steel wire refer to the recrystallization rate and grain size of 100 × 100 μm centered at a position 50 μm from the surface of the steel wire in the L-section of the steel wire (a section including the central axis of the steel wire and parallel to the central axis). By setting the recrystallization rate and grain size of the 50 μm surface layer of the steel wire to the above preferred range, a stainless steel wire after heat treatment can be obtained having a tensile strength of 600 to 1200 MPa, a reduction in size at break of 40% or more, and a pitting potential of 0.20 V or more.

[0062] (Recrystallization rate of the 50 μm surface layer of the steel wire: 0.80 or higher) By having a recrystallization rate of 0.80 or higher in the 50 μm surface layer of the stainless steel wire after heat treatment, it is possible to obtain high tensile strength and high reduction of area at fracture in the stainless steel wire after heat treatment. Furthermore, pitting corrosion occurs due to nitride precipitation in unrecrystallized grains, but by having a recrystallization rate of 0.80 or higher, the number of unrecrystallized grains is reduced, and the pitting corrosion potential can be increased. The recrystallization rate is preferably 0.90 or higher, more preferably 0.95 or higher.

[0063] (Crystal grain size of the 50 μm surface layer of the steel wire: 80 μm or less) By having a crystal grain size of 80 μm or less in the 50 μm surface layer of the stainless steel wire after heat treatment, the effect of grain refinement allows the stainless steel wire after heat treatment to obtain high tensile strength and high reduction of area at fracture. Furthermore, because the crystal grain size of the surface layer is fine, the amount of nitride per unit grain boundary in the surface layer is reduced, pitting corrosion due to sensitization is avoided, and the pitting potential can be increased. The crystal grain size of the surface layer is preferably 50 μm or less, more preferably 30 μm or less.

[0064] (Tensile strength: 600 to 1200 MPa) The stainless steel wire after heat treatment of the second embodiment preferably has a tensile strength in the range of 600 to 1200 MPa. By setting the tensile strength to 600 MPa or higher, the high strength that is the objective of the present invention can be sufficiently achieved. On the other hand, if the tensile strength exceeds 1200 MPa, sufficient reduction of area at fracture cannot be ensured. More preferably, the tensile strength is 700 to 1100 MPa. Even more preferably, the tensile strength is 800 to 1000 MPa.

[0065] (Reduction at fracture: 40% or more) The stainless steel wire after heat treatment of the second embodiment preferably has a reduction at fracture of 40% or more. By having a reduction at fracture of 40% or more, a stainless steel wire after heat treatment with high ductility can be provided. More preferably, the reduction at fracture is 50% or more, and even more preferably 60% or more.

[0066] (Pitting potential: 0.20V or higher) The stainless steel wire after heat treatment of the second embodiment preferably has a pitting potential of 0.20V or higher. By setting the pitting potential to 0.20V or higher, high corrosion resistance can be obtained. More preferably, the pitting potential is 0.30V or higher, and even more preferably, it is 0.40V or higher.

[0067] 《Method for Manufacturing Heat-Treated Stainless Steel Wire of the Second Embodiment》 By using the as-drawn stainless steel wire of the first embodiment as a material and performing the heat treatment described below, it is possible to manufacture the heat-treated stainless steel wire of the second embodiment having a recrystallization rate of 0.80 or more in the 50 μm surface layer of the steel wire and a crystal grain size of 80 μm or less in the 50 μm surface layer of the steel wire. Since the component composition does not change due to the heat treatment, the component composition range of the as-drawn stainless steel wire of the first embodiment and the heat-treated stainless steel wire of the second embodiment are the same, including the A value shown in equation (a).

[0068] The heat treatment conditions for the second embodiment are preferably a temperature of 910 to 1150°C for a time of 10 to 360 s, and more preferably a temperature of 930 to 1050°C for 20 to 80 s.

[0069] As described above, keeping the amount of work-induced martensite in the surface 50 μm of the stainless steel wire as drawn in the first embodiment to 50% or less contributes to ensuring the recrystallization rate of the surface 50 μm of the stainless steel wire and optimizing the grain size of the surface 50 μm of the stainless steel wire after heat treatment in the second embodiment. If the amount of work-induced martensite in the surface 50 μm of the stainless steel wire exceeds 50% in the first embodiment, recrystallization will be poor in the stainless steel wire after heat treatment, the recrystallization rate of the surface 50 μm of the stainless steel wire in the second embodiment will decrease, and the grain size will also increase. １５ / m ２ This also contributes to ensuring a recrystallization rate of the 50 μm surface layer of the steel wire in the second embodiment.

[0070] Stainless steel parts can be made using the stainless steel wire as drawn according to the first embodiment. Depending on the type of part, as described above, stainless steel parts may also be made using the stainless steel wire after heat treatment according to the second embodiment. Examples of stainless steel parts include wire mesh, ropes, springs, and communication cores. Since the stainless steel wire as drawn according to the first embodiment and the stainless steel wire after heat treatment according to the second embodiment each possess excellent strength and ductility, they can be suitably used as materials for the above-mentioned stainless steel parts.

[0071] The following describes embodiments of the present invention. However, the conditions in the embodiments are merely examples of conditions adopted to confirm the feasibility and effectiveness of the present invention, and the present invention is not limited to the conditions used in the following embodiments. The present invention can adopt various conditions as long as they do not depart from the spirit of the invention and achieve the objectives of the present invention.

[0072] Example 1: Table 1 shows the chemical composition (steel grades A to AU) and the A value in formula (a) of the steel used in the example. Underlined items in Table 1 are outside the scope of the present invention.

[0073]

[0074] These steels with chemical compositions were melted in a 100 kg vacuum melting furnace, assuming the AOD (Adaptive Oral Deposition) process, an inexpensive process for melting stainless steel, and cast into φ180 mm slabs. The resulting slabs were heated at 1100°C for 200 minutes, then hot-rolled to φ5.5 mm, and the hot rolling was terminated at 1050°C. Immediately afterward, an in-line heat treatment was performed at 1050°C for 3 minutes as a solution treatment, followed by water cooling and pickling to produce wire for stainless steel wire.

[0075] Subsequently, the processes of shot peening (SP), lubrication film formation, cold drawing, and solution heat treatment were repeated until the wire diameter reached φ0.15 mm. After the final drawing, solution heat treatment was omitted, and the wire was obtained as stainless steel wire as it was drawn. In the drawing process, a die with a die half-angle of 5° was used. Shot peening was performed with SUS shot at a projection speed of 50 m / s and a projection angle of 50°. No heat treatment was performed after the drawing process.

[0076] Then, the steel wires manufactured by the above method were evaluated according to the following method for the austenite phase dislocation density, the amount of work-induced martensite in the top 50 μm of the steel wire surface, tensile strength, reduction of area at fracture, and torsion value.

[0077] [Dislocation Density of Austenite Phase] The dislocation density of the austenite phase of the steel wire was measured by X-ray line profile analysis. Fourteen L-sections (sections containing the central axis of the steel wire and parallel to the central axis) were arranged side by side, and measurements were performed using CuKα rays by X-ray diffraction in a 2 mm × 10 mm area, and the full width at half maximum (FWHM) of (111), (200), (220), and (311) were measured. The obtained FWHMs were substituted into the following equation (E) (modified Williamson-Hall equation): ΔK = 0.9 / D + ((πM ２ b ２ ρ) / 2) 1 / 2 K.C. 1 / 2 +O(K ２ C) ... (E) In equation (E), D is the crystallite size (nm) and ρ is the dislocation density (m －２), b is the magnitude of the Burgers vector (nm), M is a constant relating to the dislocation density ρ and the dislocation interaction distance Re (nm), and C is the average contrast factor of the dislocations. Furthermore, K and ΔK are as follows: K = 2sinθ / λ, ΔK = 2βcosθ / λ In the above equations, β, θ, and λ are the half-width (rad), Bragg reflection angle (rad), and X-ray wavelength (CuKα = 0.15405 nm) of each diffraction line, respectively.

[0078] Here, squaring both sides of equation (E), we obtain the higher-order term O(K ２ Ignoring C), α = (0.9 / D) ２ γ = πM ２ b ２ If we set ρ / 2, we obtain equation (F). [(ΔK) ２ -α] / K ２ = γC ... (F) In the above equation, C = C ｈ００ (1-qH ２ ) ... (G) And q is a parameter that includes the type and proportion of dislocations, and H is described by the following equation (H) as a function of the indices h, k, and l of the diffraction line (hkl). H ２ = (h ２ k ２ +h ２ l ２ +k ２ l ２ ) / (h ２ +k ２ +l ２ ) ２ ... (H) Also, C ｈ００ = C ｅ ｈ００ +S(C) ｓ ｈ００ -C ｅ ｈ００ ) ... (I) and C ｅ ｈ００ , C ｓ ｈ００ This is the contrast factor in the case of 100% edge dislocations and helical dislocations, and is a constant that can be obtained from the elastic constant. The above q value can be determined as follows, and the helical dislocation fraction S of austenite can be calculated from the following relation (J): S = (q - q ｅ ) / (qｓ -q ｅ ),... Equation (J) In the above equation, q ｅ and q ｓ are the q values in the case of 100% edge dislocations and screw dislocations, respectively, and are constants determined from the elastic constants.

[0079] To determine the q value, Equations (F) and (G) are used. Let the variables on the X-axis and Y-axis be H ２ and (ΔK ２ -α ２ ) / K ２ respectively, and determine α for which the linearity is optimal with respect to H ２ . Then, obtain the q value as q = -slope / intercept from the slope and intercept in the above linear function. Obtain the S value from Equation (J) and the C value from Equation (G).

[0080] Next, perform a Fourier transform on the profile of each diffraction plane to obtain the relationship of the modified Warren-Averbach equation of Equation (K). L is the Fourier length. Approximate the relationship between lnA(L) and K ２ C for each Fourier length by a quadratic function. If the slope of the linear term of Equation (K) is set to Y(L), the relationship of Equation (L) is obtained. Y(L) / L ２ and the slope of the relationship between lnL (=πb ２ ρ / 2) to calculate the dislocation density.

[0081] The reason for limiting the evaluation of the dislocation density to "in the austenite phase" is that it is a factor necessary to ensure the strength-ductility balance of the steel wire. Also, by the above evaluation, the dislocation density in the austenite phase can be evaluated.

[0082] After evaluating the dislocation density in the austenite phase by the above procedure, it is described in Table 2. When the dislocation density is 3×10 １５ / m ２ or more and less than 30×10 １５ / m ２ , it is designated as S. When the dislocation density is 30×10 １５ / m ２ or more and less than 50×10 １５ / m ２ , it is designated as A. When the dislocation density is 1×10 １５ / m ２ or more and 3×10１５ / m ２ less than, or 50×10 １５ / m ２ or more and 100×10 １５ / m ２ or less was judged as B, and the dislocation density of 1×10 １５ / m ２ less than, or 100×10 １５ / m ２ or more was judged as X (non-conforming).

[0083] [Amount of strain-induced martensite in the 50-μm surface layer of the steel wire] The amount of strain-induced martensite in the 50-μm surface layer of the steel wire was evaluated by the amount (area ratio) of BCC, which is the crystal structure of martensite. Although ferrite having the same BCC structure may be slightly included in the amount of BCC, since the stainless steel material according to the present embodiment is mainly composed of an austenite phase, the amount of BCC was regarded as the amount of strain-induced martensite. As a measurement method, in the L cross-section of the steel wire, five 50×50-μm fields of view centered at a position 50 μm from the surface of the steel wire were measured. Then, the amount of BCC in the observed field of view was analyzed using FE-SEM / EBSD (JSM-700F, manufactured by JEOL Ltd.), and the average value of the amount of BCC in the five fields of view was calculated. When the amount of strain-induced martensite in the 50-μm surface layer of the steel wire was 30% or less, it was rated as S; when it exceeded 30% and was 40% or less, it was rated as A; when it exceeded 40% and was 50% or less, it was rated as B; and when it exceeded 50%, it was rated as X (non-conforming).

[0084] [Tensile strength] The tensile strength of the steel wire was evaluated by the tensile strength in the tensile test of JIS Z 2241. When the tensile strength was 1900 MPa or more and 3000 MPa or less, it was rated as S; when it was 1800 MPa or more and less than 1900 MPa, or exceeded 3000 MPa and was 3500 MPa or less, it was rated as A; when it was 1700 MPa or more and less than 1800 MPa, or exceeded 3500 MPa and was 4500 MPa or less, it was rated as B; and when it was less than 1700 MPa, or exceeded 4500 MPa, it was rated as X (non-conforming).

[0085] [Elongation at break] The elongation at break of the stainless steel wire was evaluated as the cross-sectional reduction rate of the fracture surface after the tensile test. When the elongation at break was 30% or more, it was rated as S; when it was 20% or more and less than 30%, it was rated as A; when it was 10% or more and less than 20%, it was rated as B; and when it was less than 10%, it was rated as X (non-conforming).

[0086] [Twist Value] The twist value was evaluated by a twist test. The twist test was conducted with a chuck distance L of 150 mm and a rotation speed of 3 rpm, and the twist value was calculated so that the chuck distance was equivalent to 100 d (wire diameter) mm. A twist value of 10 or more was rated S, 5 or more but less than 10 was rated A, 1 or more but less than 5 was rated B, and less than 1 was rated X (fail).

[0087] The evaluation results are shown in Table 2. Items that fall outside the scope of the present invention are underlined.

[0088]

[0089] As shown in Table 2, in the stainless steel wire as-drawn according to Examples 1 to 33 of the present invention, the dislocation density of the austenite phase is 1 × 10⁻⁶. １５ / m ２ ~100 x 10 １５ / m ２ In the case of the first steel wire, the amount of work-induced martensite in the 50 μm surface layer was B to S, the tensile strength was B to S, the elongation at break was B to S, and the torsion value was B to S. On the other hand, in the case of the steel wires of comparative examples 34 to 47, the dislocation density of the austenite phase did not meet the target, and the amount of work-induced martensite in the 50 μm surface layer, tensile strength, and elongation at break were all X (unacceptable) and did not meet the preferred range.

[0090] <Example 2> For steels having the composition of seven types of steel grades M to S and four types of steel grades AH to AK shown in Table 1, the shot peening conditions and die half-angle conditions were as shown in "Manufacturing Conditions" in Table 3, and the other conditions were as shown in the manufacturing conditions of Example 1, to produce stainless steel wire as drawn according to the first embodiment. Using the stainless steel wire as drawn according to the first embodiment, heat treatment was performed according to the heat treatment conditions shown in "Manufacturing Conditions" in Table 3 to produce stainless steel wire after heat treatment according to the second embodiment. The following qualities of the manufactured stainless steel wire after heat treatment were then evaluated.

[0091] [Surface Recrystallization Rate] The surface recrystallization rate (area ratio (-)) was measured in five 100 × 100 μm fields centered 50 μm from the surface of the steel wire in the L-section of the steel wire, and evaluated using FE-SEM / EBSD. Regions with a KAM value (Kernel Average Misorientation) of 1.0 or less obtained by FE-SEM / EBSD were evaluated as recrystallized structures, and the average recrystallization rate of the five fields was calculated. A recrystallization rate of 0.95 or higher was rated S, a recrystallization rate of 0.90 or higher and less than 0.95 was rated A, a recrystallization rate of 0.80 or higher and less than 0.90 was rated B, and a recrystallization rate of less than 0.80 was rated X (fail).

[0092] [Surface grain size] The surface grain size was measured by FE-SEM / EBSD analysis (JSM-700F / manufactured by JEOL Ltd.). Five fields of view of 100 × 100 μm centered 50 μm from the surface of the steel wire were measured in the L-section. The grain size was calculated using the AREA method, with the interface of grains with an orientation difference of 15° or more considered the grain boundary, and the average grain size of the five fields of view was calculated. A surface grain size of 30 μm or less was classified as S, greater than 30 μm and less than or equal to 50 μm as A, greater than 50 μm and less than or equal to 80 μm as B, and greater than 80 μm as X (fail).

[0093] [Tensile Strength] The tensile strength of heat-treated stainless steel wire was evaluated using the tensile strength test according to JIS Z 2241. A tensile strength of 800 MPa or more and 1000 MPa or less was classified as S, 700 MPa or more and less than 800 MPa, or more than 1000 MPa and 1100 MPa or less was classified as A, 600 MPa or more and less than 700 MPa, or more than 1100 MPa and 1200 MPa or less was classified as B, and less than 600 MPa or more than 1200 MPa was classified as X (fail).

[0094] [Fracture Reduction] The fracture reduction of heat-treated stainless steel wire was evaluated as the reduction in cross-sectional area of ​​the fracture surface after tensile testing. A fracture reduction of 60% or more was rated S, 50% or more but less than 60% was rated A, 40% or more but less than 50% was rated B, and less than 40% was rated X (fail).

[0095] [Pitting Potential] The evaluation of pitting potential for corrosion resistance was performed in accordance with JIS G0577:2014. The surface of the steel wire was wet-polished with #600 grit to prepare the test specimen. Next, the test specimen for pitting potential measurement was immersed in a 3.5% NaCl solution at 30°C after sufficient Ar degassing, and dynamic anodic polarization was performed from the natural potential at 20 mV / min to measure the pitting potential. The pitting potential was measured with a current of 100 μA / cm². ２ The potential was defined as the potential when the current was flowing. In this evaluation, the standard for potential was Ag / AgCl, and a pitting potential of 0.40V or higher was classified as S, 0.30V or higher and less than 0.40V as A, 0.20V or higher and less than 0.30V as B, and less than 0.20V as X (fail).

[0096] The evaluation results are shown in the "Evaluation Results of Heat-Treated Stainless Steel Wire" column of Table 3. Items outside the scope of the present invention and values ​​outside the preferred manufacturing conditions of the present invention are underlined.

[0097] For materials No. 51 to 57 of the present invention, the chemical components were within the scope of the present invention, and as a result of adopting preferred manufacturing conditions, the required quality of the second embodiment was met. On the other hand, for comparative materials No. 58 to 61, the chemical components were outside the scope of the present invention, and for comparative example No. 62, the manufacturing conditions were outside the preferred conditions of the present invention, and in all cases, the required quality of the second embodiment could not be met.

[0098]

[0099] <Example 3> Next, the influence of manufacturing conditions on the quality of the stainless steel wire as processed in the first embodiment was investigated. Furthermore, the influence of the quality of the stainless steel wire as processed in the first embodiment on the quality of the stainless steel wire after heat treatment in the second embodiment was investigated.

[0100] Using the steel grade M shown in Table 1, wire rods were manufactured in the same manner as in Example 1 above. Subsequently, the processes of shot peening (SP), lubrication film formation, cold drawing, and solution heat treatment were repeated until the diameter reached φ0.15 mm. After the final drawing, solution heat treatment was omitted, and the resulting stainless steel wire was obtained as is. In the drawing process, dies with the die half-angles shown in Table 4 were used. A comparison was also made between the presence and absence of shot peening (SP) before drawing. The results are shown in the "Manufacturing Method" and "Evaluation Results of First Embodiment (Stainless Steel Wire As Is)" columns of Table 4. For Invention Nos. 101 to 105, shot peening (SP) was performed with SUS shot at a projection speed of 50 m / s and a projection angle of 50°, and dies with a die half-angle of 3° to 9° were used. As a result, good quality was obtained for the steel wire of the first embodiment. On the other hand, Comparative Examples 106 to 109, which employed either no shot peening, a die half-angle of less than 3°, or more than 9°, or both, failed to meet the quality targets of the present invention.

[0101]

[0102] Next, using the stainless steel wire as-drawn according to the first embodiment shown in Table 4, heat treatment was performed under the conditions of 1050°C × 30s to produce the stainless steel wire after heat treatment according to the second embodiment. The quality evaluation of the stainless steel wire after heat treatment was performed in the same manner as in Example 2 above.

[0103] The evaluation results are shown in the "Evaluation Results of the Second Embodiment (Stainless Steel Wire After Heat Treatment)" column of Table 4. Items that fall outside the scope of the present invention and values ​​that deviate from the preferred manufacturing conditions of the present invention are underlined.

[0104] Materials No. 101 to 105 of the present invention, which met the required quality of the first embodiment, also met the required quality of the second embodiment. On the other hand, comparative materials No. 106 to 109, which did not meet the required quality of the first embodiment, also failed to meet the required quality of the second embodiment.

Claims

1. In mass%, C: 0.010-0.20%, Si: 0.1-4.0%, Mn: 0.1-10.0%, Ni: 2.0-15.0%, Cr: 17.0-25.0%, Mo: 0.1-4.0%, N: 0.10-0.50%, Contains Cu: 0.5-4.0%, V: 0-2.5%, B: 0-0.012%, Al: 0-2.0%, W: 0-2.5%, Ga: 0-0.0500%, Co: 0-2.5%, Sn: 0-2.5%, Ti: 0-1.0%, Nb: 0 to 2.5%, Ta: 0 to 2.5%, The composition is Ca: 0-0.012%, Mg: 0-0.012%, Zr: 0-0.012%, REM: 0-0.05%, with the remainder being Fe and impurities. The A value shown in the following formula (a) is -60 or less. It has a metallic structure mainly composed of an austenite phase, and the dislocation density of the austenite phase in the steel wire is 1 × 10⁻⁶. １５ / m ２ ~100 x 10 １５ / m ２ Stainless steel wire as-drawn, wherein the amount of work-induced martensite in the top 50 μm of the steel wire surface is 50% or less. A value = 551 - 462 (C + N) - 9.2 Si - 8.1 Mn - 29 (Ni + Cu) - 13.7 Cr - 18.5 Mo ... (a) However, the element symbols in the formula represent the content (mass %) of the element in the steel. Also, if the content of an element in formula (a) is 0%, "0" is substituted in place of the corresponding symbol in the calculation.

2. The stainless steel as-drawn wire according to claim 1, further containing, by mass%, one or more selected from V: 0.001 to 2.5%, B: 0.001 to 0.012%, Al: 0.001 to 2.0%, W: 0.05 to 2.5%, Ga: 0.0004 to 0.0500%, Co: 0.05 to 2.5%, Sn: 0.01 to 2.5%, Ti: 0.01 to 1.0%, Nb: 0.01 to 2.5%, Ta: 0.01 to 2.5%, Ca: 0.0002 to 0.012%, Mg: 0.0002 to 0.012%, Zr: 0.0002 to 0.012%, and REM: 0.0002 to 0.05%.

3. Stainless steel wire as drawn according to claim 1 or claim 2, wherein the tensile strength is 1700 to 4500 MPa, the reduction of area at break is 10% or more, and the twist value (100d) is 1 or more.

4. In mass %, C: 0.010-0.20%, Si: 0.1-4.0%, Mn: 0.1-10.0%, Ni: 2.0-15.0%, Cr: 17.0-25.0%, Mo: 0.1-4.0%, N: 0.10-0.50%, Contains Cu: 0.5-4.0%, V: 0-2.5%, B: 0-0.012%, Al: 0-2.0%, W: 0-2.5%, Ga: 0-0.0500%, Co: 0-2.5%, Sn: 0-2.5%, Ti: 0-1.0%, Nb: 0 to 2.5%, Ta: 0 to 2.5%, Stainless steel wire after heat treatment, having the following composition: Ca: 0-0.012%, Mg: 0-0.012%, Zr: 0-0.012%, REM: 0-0.05%, with the remainder being Fe and impurities, an A value of -60 or less as shown in the following formula (a), a recrystallization rate of 0.80 or more in the 50 μm surface layer of the steel wire, and a grain size of 80 μm or less in the 50 μm surface layer of the steel wire. A value = 551 - 462 (C + N) - 9.2 Si - 8.1 Mn - 29 (Ni + Cu) - 13.7 Cr - 18.5 Mo ... (a) However, the element symbols in the formula represent the content (mass %) of the element in the steel. Also, if the content of an element in formula (a) is 0%, "0" is substituted in place of the corresponding symbol in the calculation.

5. The stainless steel heat-treated wire according to claim 4, further containing, by mass%, one or more selected from V: 0.001 to 2.5%, B: 0.001 to 0.012%, Al: 0.001 to 2.0%, W: 0.05 to 2.5%, Ga: 0.0004 to 0.0500%, Co: 0.05 to 2.5%, Sn: 0.01 to 2.5%, Ti: 0.01 to 1.0%, Nb: 0.01 to 2.5%, Ta: 0.01 to 2.5%, Ca: 0.0002 to 0.012%, Mg: 0.0002 to 0.012%, Zr: 0.0002 to 0.012%, and REM: 0.0002 to 0.05%.

6. Stainless steel wire after heat treatment according to claim 4 or claim 5, wherein the tensile strength is 600 to 1200 MPa, the reduction of area at break is 40% or more, and the pitting potential is 0.20 V or more.

7. In mass%, C: 0.010-0.20%, Si: 0.1-4.0%, Mn: 0.1-10.0%, Ni: 2.0-15.0%, Cr: 17.0-25.0%, Mo: 0.1-4.0%, N: 0.10-0.50%, Contains Cu: 0.5-4.0%, V: 0-2.5%, B: 0-0.012%, Al: 0-2.0%, W: 0-2.5%, Ga: 0-0.0500%, Co: 0-2.5%, Sn: 0-2.5%, Ti: 0-1.0%, Nb: 0 to 2.5%, Ta: 0 to 2.5%, A wire material for stainless steel wire, having the following composition: Ca: 0-0.012%, Mg: 0-0.012%, Zr: 0-0.012%, REM: 0-0.05%, with the remainder being Fe and impurities, and having an A value of -60 or less as shown in the following formula (a): A value = 551 - 462 (C + N) - 9.2 Si - 8.1 Mn - 29 (Ni + Cu) - 13.7 Cr - 18.5 Mo ... (a) However, the element symbols in formula (a) represent the content (mass%) of the element in the steel. Also, if the content of an element in formula (a) is 0%, "0" is substituted in place of the corresponding symbol in the calculation.

8. The wire material for stainless steel wire according to claim 7, further containing, by mass%, one or more selected from V: 0.001 to 2.5%, B: 0.001 to 0.012%, Al: 0.001 to 2.0%, W: 0.05 to 2.5%, Ga: 0.0004 to 0.0500%, Co: 0.05 to 2.5%, Sn: 0.01 to 2.5%, Ti: 0.01 to 1.0%, Nb: 0.01 to 2.5%, Ta: 0.01 to 2.5%, Ca: 0.0002 to 0.012%, Mg: 0.0002 to 0.012%, Zr: 0.0002 to 0.012%, and REM: 0.0002 to 0.05%.

Images