Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
  • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
  • C21D8/06—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
  • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
  • C21D9/525—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length for wire, for rods
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/008—Ferrous alloys, e.g. steel alloys containing tin
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D2211/00—Microstructure comprising significant phases
  • C21D2211/003—Cementite
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D2211/00—Microstructure comprising significant phases
  • C21D2211/005—Ferrite
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D2211/00—Microstructure comprising significant phases
  • C21D2211/008—Martensite
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D2211/00—Microstructure comprising significant phases
  • C21D2211/009—Pearlite
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur

Definitions

• This disclosure relates to wire rods, steel wires, ropes, and methods for manufacturing ropes.
• Patent Document 1 discloses a high-strength PC steel wire having a tensile strength of 2000 MPa or more, which contains, by mass%, 0.9 to 1.2% C, 0.01 to 1.5% Si, 0.2 to 1.5% Mn, 0.001 to 0.05% Al, and 0.0005 to 0.010% N, with the balance being Fe and unavoidable impurities, and which is made up of 90% or more of drawn pearlite and 10% or less of ferrite and bainite structure, and has a tensile strength of 2000 MPa or more, and which has excellent delayed fracture resistance, characterized in that, when the wire diameter of the PC steel wire is D, the ratio (Hv surface/Hv interior) of the surface layer Hv hardness (Hv surface) in a region 0.1D from the surface of the PC steel wire (surface layer portion) to the internal Hv hardness (Hv internal) of the region (internal) inside the surface layer portion is 1.1 or less.
• the torsional properties decrease
• Patent Document 2 discloses a plated steel wire for PWS having excellent torsional properties, which contains, by mass%, 0.8 to 1.1% C, 0.8 to 1.3% Si, 0.3 to 0.8% Mn, 0.001 to 0.006% N, and 0.0004 to 0.0060% B, and contains 0.0002% or more of solid-solubilized B, and further contains one or two of 0.005 to 0.1% Al and 0.005 to 0.1% Ti, with the balance being Fe and unavoidable impurities, the area ratio of non-pearlite structures in a portion to a depth of 50 ⁇ m from the surface layer is 10% or less, the total area ratio of non-pearlite structures in the entire cross section is 5% or less, and the surface is coated with zinc plating with a plating coating weight of 300 to 500 g/m 2 .
• Patent Document 1 JP 2009-280836 A Patent Document 2: WO 2008/093466
• an object of the present disclosure is to provide a wire rod suitable for producing a steel wire having high strength and excellent torsional properties by wiredrawing, a steel wire having high strength and excellent torsional properties, a rope, and a method for producing the rope.
• Means for solving the above problems include the following aspects. ⁇ 1> In mass%, C: 0.80-1.10%, Si: 0.10 to 1.50%, Mn: 0.10-1.00%, P: 0.030% or less, S: 0.030% or less, N: 0.0120% or less, O: 0.0100% or less, Al: 0.005-0.070%, Mo: 0.02-0.20%, Cr: 0-1.00%, Cu: 0 to 0.80%, Sn: 0 to 0.50%, Ni: 0 to 0.50%, V: 0 to 0.15%, Ti: 0 to 0.050%, Nb: 0 to 0.050%, B: 0 to 0.0040%, REM: 0-0.030%, Mg: 0 to 0.0040%, Ca: 0-0.0040%, Zr: 0 to 0.030%, W: 0-0.10%, Te: 0 to 0.030%, and Sb: 0 to 0.030%, and the balance being Fe and impurities, In a cross section perpendicular to the
• the chemical composition is, in mass%, Cr: 0.03-1.00%, Cu: 0.01-0.80%, Sn: 0.001 to 0.50%, Ni: 0.01 to 0.50%, and V: 0.01 to 0.15%
• the wire according to ⁇ 1> comprising at least one or more selected from the group consisting of: ⁇ 3>
• the chemical composition is, in mass%, Ti: 0.002 to 0.050%, Nb: 0.002 to 0.050%, B: 0.0003 to 0.0040%, REM: 0.002-0.030%, Mg: 0.0002-0.0040%, Ca: 0.0002-0.0040%, Zr: 0.002 to 0.030%, W: 0.02-0.10%, Te: 0.001 to 0.030%, and Sb: 0.001 to 0.030%
• the wire according to ⁇ 1> or ⁇ 2> comprising one or more selected from the group consisting of: ⁇ 4> In mass%, C: 0.80 to 1.10%, Si: 0.10 to 1.50%, Mn: 0.1
• the chemical composition is, in mass%, Cr: 0.03-1.00%, Cu: 0.01-0.80%, Sn: 0.001 to 0.50%, Ni: 0.01 to 0.50%, and V: 0.01 to 0.15%,
• the steel wire according to ⁇ 4> comprising at least one or more selected from the group consisting of: ⁇ 6>
• the chemical composition is, in mass%, Ti: 0.002 to 0.050%, Nb: 0.002 to 0.050%, B: 0.0003 to 0.0040%, REM: 0.002-0.030%, Mg: 0.0002-0.0040%, Ca: 0.0002-0.0040%, Zr: 0.002 to 0.030%, W: 0.02-0.10%, Te: 0.001 to 0.030%, and Sb: 0.001 to 0.030%,
• the steel wire according to ⁇ 4> or ⁇ 5> comprising one or more selected from the group consisting of: ⁇ 7>
• a rope comprising a plurality of steel wires according to any one of ⁇ 4> to ⁇ 7> bound together.
• a method for producing a rope comprising a step of bundling a plurality of the steel wires according to any one of ⁇ 4> to ⁇ 7> to form a rope.
• a wire rod suitable for producing a steel wire having high strength and excellent torsional properties through wire drawing, a steel wire having high strength and excellent torsional properties, a rope, and a method for producing the rope are provided.
• FIG. 2 is a diagram showing an example of a SEM photograph of each structure of a wire rod.
• FIG. 2 is a diagram showing an example of a SEM photograph of a ferrite structure and a martensite structure of a steel wire.
• the "surface layer” or “surface portion” of the wire means a range of 0.5 to 1.0 mm deep from the surface (outer surface) of the wire in a cross section perpendicular to the longitudinal direction of the wire (a region having a depth of 0.5 mm or more and 1.0 mm or less from the surface), and the "center portion” means a range within 1.0 mm from the center of the wire in a cross section perpendicular to the longitudinal direction of the wire.
• the "surface layer” or “surface portion” of a steel wire means a range of 0.2 to 0.5 mm deep from the surface (outer surface) of the steel wire in a cross section parallel to or perpendicular to the longitudinal direction of the steel wire (a region having a depth of 0.2 mm or more and 0.5 mm or less from the surface), and the "center portion” means a range within 1.0 mm from the center of the steel wire in a cross section parallel to or perpendicular to the longitudinal direction of the steel wire.
• the "central axis” means an imaginary line that passes through the center point of a cross section perpendicular to the axial direction (longitudinal direction) of the wire rod or steel wire and extends in the axial direction.
• a cross section perpendicular to the longitudinal direction of a wire rod or steel wire may be referred to as a "transverse cross section,” and a cross section parallel to the longitudinal direction and including the central axis may be referred to as a "longitudinal cross section.”
• a numerical range expressed using “to” means a range that includes the numerical values before and after "to” as the lower and upper limits.
• the numerical values before and after “to” are followed by "more than” or “less than,” the numerical range does not include these numerical values as the lower or upper limit.
• the upper limit value of a certain numerical range may be replaced by the upper limit value of another numerical range described in stages, or may be replaced by a value shown in the examples.
• the lower limit value of a certain numerical range may be replaced by the lower limit value of another numerical range described in stages, or may be replaced by a value shown in the examples.
• the content of an element in a chemical composition may be expressed simply as "amount” (for example, C amount, Si amount, etc.). With regard to the contents of elements in chemical compositions, "%" means “mass %".
• the wire according to the present disclosure is In mass percent, C: 0.80-1.10%, Si: 0.10 to 1.50%, Mn: 0.10-1.00%, P: 0.030% or less, S: 0.030% or less, N: 0.0120% or less, O: 0.0100% or less, Al: 0.005 to 0.070%, and Mo: 0.02 to 0.20%, Including, Optionally, Cr: 0-1.00%, Cu: 0 to 0.80%, Sn: 0 to 0.50%, Ni: 0 to 0.50%, V: 0 to 0.15%, Ti: 0 to 0.050%, Nb: 0 to 0.050%, B: 0 to 0.0040%, REM: 0-0.030%, Mg: 0 to 0.0040%, Ca: 0-0.0040%, Zr: 0 to 0.030%, W: 0-0.10%, Te: 0 to 0.030%, and Sb: 0 to 0.030%, and the balance being Fe and impurities.
• the total area ratio of the ferrite structure and the martensite structure in the central portion within 1.0 mm from the center (sometimes referred to as the "area ratio of the ferrite structure and the martensite structure" in the present disclosure) is 5% or less, and the remainder is a mixed structure consisting of ferrite and cementite
• the average Vickers hardness (sometimes referred to as “average hardness” in this disclosure) H in the cross section satisfies formula (1), 480 ⁇ [C]-40 ⁇ H ⁇ 480 ⁇ [C]+40...(1)
• the surface layer Vickers hardness Hs at a depth of 0.5 to 1.0 mm from the surface (sometimes referred to as the “surface layer hardness” in this disclosure) and the average Vickers hardness H satisfy the relationship of formula (2), 0 ⁇ Hs-H ⁇ 30...(2)
• the inventors of the present disclosure have found the wire rod and steel wire according to the present disclosure through the following studies.
• a mixed structure of ferrite and cementite such as pearlite or bainite, which has excellent work hardening ability, as the main structure.
• the presence of a structure that contains almost no cementite reduces the torsional properties.
• pearlite and bainite are not distinguished in this disclosure because, if they have the same hardness, their properties after wire drawing are similar and it is difficult to distinguish them from photographs as structures.
• the wire diameter of the wire rod often exceeds 7.0 mm.
• the hardness distribution formed in the wire rod is carried over to the wire drawing process, and the steel wire also has a hard surface distribution. In a torsion test, strain is concentrated in the surface layer, so a hard surface distribution is disadvantageous in torsion characteristics.
• the inventors of the present disclosure therefore investigated ways to sufficiently delay the transformation so that pearlite or bainite transformation can occur at the same temperature as the surface layer, even in the center where the cooling rate is slow.
• the inventors of the present disclosure discovered that Mo has the effect of delaying the transformation, and that the addition of Mo improves the uniformity of the hardness distribution in the wire's cross section (cross section perpendicular to the longitudinal direction of the wire), and further confirmed that steel wire containing a specified amount of Mo has good torsional properties even when the tensile strength is 2050 MPa or more.
• C 0.80-1.10%
• C is a component necessary for increasing the tensile strength of the wire rod and the steel wire obtained after wire drawing. If the C content is less than 0.80%, the tensile strength is insufficient. On the other hand, if the C content of the wire rod is too high, the wire rod becomes hard and the torsional properties deteriorate. If the C content of the wire rod exceeds 1.10%, it becomes difficult to suppress the formation of pro-eutectoid cementite. Even if other requirements are met, the desired torsional properties cannot be obtained. From the viewpoint of tensile strength, the C content is preferably 0.85% or more, and more preferably 0.90% or more. On the other hand, from the viewpoint of torsional properties, the C content is preferably 1.05% or more. % or less, and particularly when it is 1.00% or less, better characteristics are exhibited.
• Si 0.10 ⁇ 1.50% Silicon is an effective component for increasing the tensile strength of the wire rod and the steel wire obtained after wire drawing. If the Si content of the wire rod is less than 0.10%, the effect of containing Si cannot be sufficiently obtained. On the other hand, if the Si content of the wire exceeds 1.50%, it becomes difficult to suppress the formation of the martensite structure, which is a hard phase, and even if other requirements are met, the target torsional properties cannot be obtained. I can't. From the viewpoint of tensile strength, the Si content is preferably 0.50% or more, and more preferably 0.70% or more. On the other hand, from the viewpoint of torsional properties, the Si content is 1.40% or more. % or less, and more preferably 1.30% or less, better characteristics are exhibited.
• Mn 0.10-1.00%
• Mn is an effective component for increasing the tensile strength of wire rods and steel wires obtained after wire drawing. Mn also fixes S in steel as MnS, suppressing hot brittleness. It is an ingredient that has an effect. If the Mn content of the wire rod is less than 0.10%, the effect of containing Mn cannot be sufficiently obtained. On the other hand, if the wire rod contains more than 1.00% Mn, it becomes difficult to suppress the formation of the martensite structure, which is a hard phase, and even if other requirements are met, the target torsional properties may not be achieved. Not obtained. From the viewpoint of tensile strength, the Mn content is preferably 0.25% or more, while from the viewpoint of torsional properties, the Mn content is preferably 0.80% or less.
• P 0.030% or less
• P is an element that segregates at grain boundaries of a wire rod and deteriorates the torsional properties. If the P content of the wire rod is 0.030% or less, the deterioration of the torsional properties is suppressed, and the target torsional properties can be obtained by satisfying other requirements.
• the upper limit of the P content is preferably 0.025%, and more preferably 0.020% or less.
• the lower limit of the P content is not limited and is preferably 0% (i.e., no P content), but may be more than 0% or may be 0.001% or more from the viewpoint of reducing the dephosphorization cost.
• S 0.030% or less S is an element that deteriorates the torsional properties. If the S content of the wire rod is 0.030% or less, the target torsional properties can be obtained while satisfying other requirements.
• the upper limit of the S content is preferably 0.020%.
• the lower limit of the S content is not limited, but may be more than 0% or may be 0.001% or more from the viewpoint of reducing the desulfurization cost.
• N 0.0120% or less
• N is an element that deteriorates the torsional properties. If the N content of the wire rod is 0.0120% or less, the target torsional properties can be obtained by satisfying other requirements.
• the upper limit of the N content is preferably 0.0100%, and more preferably 0.0070%.
• the lower limit of the N content is not limited, but may be more than 0% or may be 0.0001% or more from the viewpoint of reducing refining costs.
• O 0.0100% or less
• O is an element that is likely to form oxide-based inclusions in the wire rod. If the O content of the wire rod is 0.0100% or less, the oxide-based inclusions are prevented from becoming coarse, and the deterioration of the torsional properties can be suppressed.
• the upper limit of the O content is preferably 0.0070%, and more preferably 0.0050%.
• the lower limit of the O content is not limited, but may be more than 0% or may be 0.0001% or more from the viewpoint of reducing refining costs.
• Al 0.005% to 0.070%
• Al is an element having a deoxidizing effect and is necessary for reducing the amount of oxygen in the wire rod. If the Al content of the wire rod is less than 0.005%, it is difficult to obtain the effect of containing Al. On the other hand, Al is an element that easily forms hard oxide-based inclusions. If the Al content of the wire rod exceeds 0.070%, coarse oxide-based inclusions are significantly more likely to form, and the wire drawing process becomes difficult. The deterioration of workability becomes significant. From the viewpoint of the deoxidizing effect, the Al content is preferably 0.010% or more, and may be 0.020% or more. On the other hand, from the viewpoint of wire drawing workability, the Al content is 0.050% or less. is preferable, and may be 0.040% or less.
• Mo 0.02 ⁇ 0.20%
• Mo is an element that can delay pearlite transformation and bainite transformation even in a small amount, and is an element that is particularly effective in improving the strength of the center part of a wire rod having a wire diameter of 7.0 mm or more. It has the effect of increasing the tensile strength of the steel wire obtained after processing. If the Mo content of the wire rod is less than 0.02%, the effect of containing Mo cannot be obtained sufficiently. On the other hand, if the Mo content of the wire exceeds 0.20%, it becomes difficult to suppress the formation of the martensite structure, which is a hard phase, and even if other requirements are met, the target torsional properties cannot be obtained. I can't.
• the Mo content is preferably 0.025% or more, and particularly 0.03% or more shows better properties.
• the Mo content is 0.15% or more. % or less, and particularly when it is 0.12% or less, better characteristics are exhibited.
• the wire rod according to the present disclosure may contain, in place of a portion of Fe, one or more of the following optional elements: Cr, Cu, Ni, Sn, V, Ti, Nb, B, REM, Mg, Ca, Zr, W, Te, and Sb. These optional elements may not be included (i.e., 0%), or may be included within the following ranges. When these optional elements are included, the lower limit of the content may be greater than 0%. For example, one or more elements selected from the group consisting of Cr, Cu, Sn, Ni, and V may be included, or one or more elements selected from the group consisting of Ti, Nb, B, REM, Mg, Ca, Zr, W, Te, and Sb may be included.
• Cr 0-1.00%
• Cr has the effect of increasing the tensile strength of the wire rod and the steel wire obtained after wire drawing.
• the Cr content is preferably 0.03% or more. If the Cr content exceeds 1.00%, it becomes difficult to suppress the formation of a martensite structure, which is a hard phase, and the torsional properties deteriorate. Therefore, when Cr is intentionally contained in the wire rod, the Cr content is preferably within the range of 0.03 to 1.00%. Also, it may be preferably 0.85% or less. More preferably, it may be 0.10% or less. ⁇ 0.70%.
• Cu 0-0.80%
• the inclusion of Cu is optional.
• Cu has the effect of enhancing the corrosion resistance of the wire rod and the steel wire obtained after wire drawing. In order to stably obtain this effect, it is preferable that the Cu content be 0.01% or more. On the other hand, even if the Cu content of the wire rod exceeds 0.80%, the effect is saturated. Therefore, when Cu is intentionally contained in the wire rod, the Cu content is preferably within a range of 0.01 to 0.80%, and more preferably 0.05 to 0.60%.
• Sn 0-0.50%
• Sn has the effect of enhancing the corrosion resistance of the wire rod and the steel wire obtained after wire drawing.
• the Sn content is preferably 0.005% or more.
• the Sn content is preferably within a range of 0.001 to 0.50%, and more preferably 0.005 to 0.40%.
• Ni 0-0.50%
• Ni has the effect of enhancing the corrosion resistance of wire rods and steel wires obtained after wire drawing. In order to stably obtain this effect, it is preferable that the Ni content be 0.01% or more. On the other hand, even if the Ni content of the wire rod exceeds 0.50%, the effect is saturated. Therefore, when Ni is intentionally contained in the wire rod, the Ni content is preferably within a range of 0.01 to 0.50%, and more preferably 0.05 to 0.40%.
• V 0 to 0.15%
• V has the effect of increasing the tensile strength of the wire rod and the steel wire obtained after wire drawing. In order to stably obtain this effect, it is preferable that the V content of the wire rod is 0.01% or more. On the other hand, if the V content of the wire exceeds 0.15%, the torsional properties are deteriorated. Therefore, when V is intentionally contained in the wire rod, the V content of the wire rod is preferably 0.02 to 0.15%, more preferably 0.03% to 0.13%, and further preferably 0.05% to 0.12%.
• Ti 0 ⁇ 0.050%
• Ti has the effect of forming carbides or carbonitrides in the wire rod to improve the torsional properties. To obtain this effect, it is preferable that the Ti content of the wire rod is 0.002% or more. On the other hand, if the Ti content of the wire exceeds 0.050%, coarse carbides or carbonitrides are likely to be formed, and the torsional properties are deteriorated. Therefore, when Ti is intentionally contained in the wire rod, the Ti content of the wire rod is preferably 0.002 to 0.050%, and more preferably 0.005 to 0.030%. .
• Nb 0-0.050%
• Nb has the effect of forming carbides or carbonitrides in the wire rod to improve the torsional properties.
• the Nb content of the wire rod is preferably 0.002% or more.
• the Nb content of the wire exceeds 0.050%, coarse carbides or carbonitrides are likely to be formed, and the torsional properties are deteriorated. Therefore, when Nb is intentionally contained in the wire rod, the Nb content of the wire rod is preferably 0.002 to 0.050%, and more preferably 0.005 to 0.030%.
• B 0-0.0040%
• B has the effect of suppressing the ferrite structure and improving the torsional properties.
• the B content of the wire rod is preferably 0.0003% or more.
• the B content of the wire rod is preferably 0.0003 to 0.0040%, and more preferably 0.0006 to 0.0030%.
• REM 0-0.030%
• the inclusion of REM is optional. If REM is contained, the wire rod can exhibit high torsional properties more stably. To obtain this effect, the REM content of the wire rod is preferably 0.002% or more. On the other hand, when the REM content of the wire rod exceeds 0.030%, the effect becomes saturated. Therefore, when REM is intentionally contained, the REM content of the wire rod is preferably set to 0.002 to 0.030%.
• REM refers to a total of 17 elements, namely Sc, Y, and lanthanoids
• the REM content refers to the content of one type of REM when there is one type of REM, and refers to the total content of the REM when there are two or more types of REM.
• Mg 0-0.0040%
• the inclusion of Mg is optional. If Mg is contained, the wire rod can exhibit high torsional properties more stably. To obtain this effect, the Mg content of the wire rod is preferably 0.0002% or more. On the other hand, when the Mg content of the wire rod exceeds 0.0040%, the effect is saturated. Therefore, when Mg is intentionally contained in the wire rod, the Mg content of the wire rod is preferably 0.0002 to 0.0040%.
• Ca 0-0.0040%
• the inclusion of Ca is optional. If Ca is contained, the wire rod can exhibit high torsional properties more stably. To obtain this effect, the Ca content of the wire rod is preferably 0.0002% or more. On the other hand, when the Ca content of the wire rod exceeds 0.0040%, the effect is saturated. Therefore, when Ca is intentionally contained in the wire rod, the Ca content of the wire rod is preferably 0.0002 to 0.0040%.
• Zr 0-0.030%
• the inclusion of Zr is optional. If Zr is contained, the wire rod can exhibit high torsional properties more stably. To obtain this effect, the Zr content of the wire rod is preferably 0.002% or more. On the other hand, if the Zr content of the wire rod exceeds 0.030%, coarse carbides or carbonitrides are likely to be formed, and the torsional properties are deteriorated. Therefore, when Zr is intentionally contained in the wire rod, the Zr content of the wire rod is preferably 0.002 to 0.030%.
• W 0 to 0.10%
• the wire rod can exhibit high torsional properties more stably.
• the W content of the wire rod is preferably 0.02% or more.
• the W content of the wire rod exceeds 0.10%, the effect is saturated. Therefore, when W is intentionally contained in the wire rod, the W content of the wire rod is preferably 0.02 to 0.10%.
• Te 0 ⁇ 0.030%
• the inclusion of Te is optional. If the wire contains Tellurium, it can exhibit high twisting properties more stably. To obtain this effect, the Tellurium content of the wire is preferably 0.001% or more. On the other hand, when the Te content of the wire exceeds 0.030%, the effect is saturated. Therefore, when Tellurium is intentionally contained in the wire rod, the Tellurium content of the wire rod is preferably 0.001 to 0.030%.
• Sb 0-0.030%
• Sb content of the wire rod is preferably 0.001% or more.
• Sb content of the wire rod exceeds 0.030%, the effect is saturated. Therefore, when Sb is intentionally contained in the wire rod, the Sb content of the wire rod is preferably 0.001 to 0.030%.
• Total area ratio of ferrite structure and martensite structure at the center of cross section The total area ratio of the ferrite structure and the martensite structure in the center of the cross section (cross section perpendicular to the longitudinal direction) of the wire is 5% or less. These deteriorate the torsional properties of the steel wire after wire drawing. If the total area ratio of the ferrite structure and the martensite structure in the center of the wire is 5% or less, the total area ratio of the ferrite structure and the martensite structure including the surface layer is low, so the center is measured as a representative.
• the total area ratio of the ferrite structure and the martensite structure in the center of the cross section of the wire may be 4% or less, 2% or less, or 1% or less. Note that either the ferrite structure or the martensite structure may be included, or neither may be included. The same applies to the structure in the longitudinal section of the steel wire described later.
• the wire according to the present disclosure has an average Vickers hardness H in a cross section that satisfies formula (1). 480 ⁇ [C]-40 ⁇ H ⁇ 480 ⁇ [C]+40...(1)
• the average Vickers hardness H in the cross section depends on the carbon content [C] in mass% contained in the wire rod. If the average value of the Vickers hardness is below "480 x [C] - 40", it is difficult to stably impart the tensile strength (e.g., 2050 MPa or more) required for the steel wire after wire drawing.
• the average Vickers hardness H may be in a range satisfying the following formula (1A) or may be in a range satisfying the following formula (1B). 480 ⁇ [C]-30 ⁇ H ⁇ 480 ⁇ [C]+30...(1A) 480 ⁇ [C]-20 ⁇ H ⁇ 480 ⁇ [C]+20...(1B)
• the surface layer Vickers hardness Hs at a depth of 0.5 to 1.0 mm from the surface and the average Vickers hardness H satisfy the relationship of formula (2): 0 ⁇ Hs ⁇ H ⁇ 30 (2) If the surface layer Vickers hardness Hs is 30 or more greater than the average Vickers hardness H, microcracks are likely to occur during the torsion test, and the target torsion test results cannot be obtained even if other requirements are met. On the other hand, it is industrially difficult to make the surface layer Vickers hardness Hs lower than the average Vickers hardness H in a normal rolled wire rod.
• the relationship between the surface layer Vickers hardness Hs and the average Vickers hardness H may be in a range satisfying the following formula (2A) or in a range satisfying the following formula (2B). 0 ⁇ Hs-H ⁇ 25...(2A) 0 ⁇ Hs-H ⁇ 20...(2B)
• the central Vickers hardness Hc and the average Vickers hardness H within 1.0 mm from the center in the cross section satisfy the relationship of formula (3). 0 ⁇ H-Hc ⁇ 30...(3)
• the central Vickers hardness Hc is smaller than the average Vickers hardness H by 30 or more, it is difficult to stably impart the tensile strength (for example, 2050 MPa or more) required for the steel wire after wire drawing. It is industrially difficult to make the center Vickers hardness Hc higher than the average Vickers hardness H in a normal rolled wire rod.
• the relationship between the central Vickers hardness Hc and the average Vickers hardness H may be in a range that satisfies the following formula (3A) or in a range that satisfies the following formula (3B). 0 ⁇ H-Hc ⁇ 25...(3A) 0 ⁇ H-Hc ⁇ 20...(3B)
• the wire rod according to the present disclosure has a wire diameter of 7.0 mm or more. If the wire rod has a wire diameter of less than 7.0 mm, the effect of the present disclosure cannot be obtained. On the other hand, although there is no particular upper limit to the wire diameter of the wire according to the present disclosure, it is difficult to industrially produce a wire having a diameter of more than 20 mm using a normal manufacturing process.
• the wire diameter of the wire according to the present disclosure may be 7.5 to 18.0 mm, or 8.0 to 16.0 mm.
• the steel wire according to the present disclosure comprises, in mass%, C: 0.80-1.10%, Si: 0.10 to 1.50%, Mn: 0.10-1.00%, P: 0.030% or less, S: 0.030% or less, N: 0.0120% or less, O: 0.0100% or less, Al: 0.005 to 0.070%, and Mo: 0.02 to 0.20%, Including, Optionally, Cr: 0-1.00%, Cu: 0 to 0.80%, Sn: 0 to 0.50%, Ni: 0 to 0.50%, V: 0 to 0.15%, Ti: 0 to 0.050%, Nb: 0 to 0.050%, B: 0 to 0.0040%, REM: 0-0.030%, Mg: 0 to 0.0040%, Ca: 0-0.0040%, Zr: 0 to 0.030%, W: 0-0.10%, Te: 0 to 0.030%, and Sb: 0 to 0.030%, 0 to 0.030%
• the steel wire according to the present disclosure is parallel to the longitudinal direction, and in a cross section passing through the central axis, the total area ratio of the ferrite structure and the martensite structure in the central portion is 5% or less, and the remainder is a mixed structure consisting of ferrite and cementite,
• the average Vickers hardness h in a cross section perpendicular to the longitudinal direction is 450 to 620;
• the surface layer Vickers hardness hs at a depth of 0.2 to 0.5 mm from the surface and the average Vickers hardness h satisfy the relationship of formula (4), 0 ⁇ hs ⁇ h ⁇ 30 (4)
• the central Vickers hardness hc within 1.0 mm from the center of the vertical cross section and the average Vickers hardness h satisfy the relationship of formula (5).
• the steel wire according to the present disclosure may be plated with zinc or a zinc alloy, or may be heat-inputted by degreasing. That is, the steel wire according to the present disclosure also includes a steel wire having a plated surface (plated wire).
• the steel wire according to the present disclosure has a plating layer, the chemical composition, metal structure, and hardness in the present disclosure all refer to values of the steel part.
• the steel wire according to the present disclosure may contain optional elements similar to those in the chemical composition of the wire rod described above.
• the wire diameter of the steel wire according to the present disclosure is not particularly limited, but may be, for example, 3.0 to 8.0 mm, or 4.0 to 7.5 mm.
• ⁇ Measurement method> methods for measuring and evaluating the area ratio and hardness of the metal structure of the wire rod and steel wire according to the present disclosure will be described. Note that the values in the examples described below are values measured by the following measurement methods. In the following description, the diameter of the wire rod or steel wire to be measured is designated as D.
• the ferrite structure and the martensite structure do not contain cementite, and the mixed structure consisting of ferrite and cementite is pearlite, bainite, etc., in which cementite is mixed in ferrite.
• a pearlite structure (an example of a mixed structure of ferrite and cementite) which is a layered structure of ferrite (black part) and cementite (whitish part) is present, but the part indicated by the arrow does not contain cementite and is distinguished from the surrounding pearlite structure, so it is judged to be a ferrite structure.
• the two arrow parts are a structure in which more ferrite exists than cementite, but split cementite exists in the ferrite, and it is judged to be a mixed structure of ferrite and cementite.
• the area ratio (%) of the ferrite structure and the martensite structure is measured in each SEM photograph.
• the ferrite structure and the martensite structure which are structures that do not contain cementite, do not necessarily need to be distinguished from each other. Specifically, after each SEM image is printed on a paper surface, a transparent sheet such as an OHP (Over Head Projector) sheet is placed on the paper surface to color the structures that do not contain cementite (ferrite structure and martensite structure).
• OHP Over Head Projector
• the transparent sheet on which the ferrite structure and the martensite structure are colored is analyzed by image analysis to measure the total area ratio of the ferrite structure and the martensite structure.
• the area per field of view is set to 2.7 x 10 -3 mm 2 (length 0.045 mm, width 0.060 mm), and image analysis is performed using image analysis software (for example, Luzex AP manufactured by Nireco Corporation).
• image analysis software for example, Luzex AP manufactured by Nireco Corporation.
• the average value is calculated from the total area ratio of the ferrite structure and the martensite structure of the five images, and the average value is the total area ratio of the ferrite structure and the martensite structure of the wire.
• the ferrite structure and the martensite structure are structures that do not contain cementite, and the mixed structure consisting of ferrite and cementite is a structure in which pearlite, bainite, etc. are wire-drawn, and cementite is mixed in the ferrite.
• the area ratio (%) of the ferrite structure and the martensite structure is measured in each SEM photograph.
• the ferrite structure and the martensite structure, which are structures that do not contain cementite do not necessarily need to be distinguished from each other. Specifically, each SEM image is printed on a paper surface, and then a transparent sheet such as an OHP (Over Head Projector) sheet is placed on the paper surface to paint the ferrite structure and the martensite structure.
• OHP Over Head Projector
• the colored transparent sheet is then analyzed by image analysis to measure the total area ratio of the ferrite structure and the martensite structure.
• the area per field is 3 ⁇ 10 ⁇ 4 mm 2 (0.015 mm long, 0.02 mm wide), and image analysis is performed using image analysis software (e.g., Luzex AP manufactured by Nireco Corporation).
• image analysis software e.g., Luzex AP manufactured by Nireco Corporation.
• the average value is calculated from the area ratios of the ferrite structure and the martensite structure of the five images, and the average value is regarded as the total area ratio of the ferrite structure and the martensite structure of the steel wire.
• the central portion is defined as a portion within a range of 1.0 mm from the center (the central axis of the wire) in the cross section, and a point is struck at the center, 0.5 mm, and 1.0 mm from the center, for a total of nine points, and the average value of the hardness measurements is defined as the central Vickers hardness Hc.
• the average Vickers hardness is the average value of the Vickers hardness measured over the entire cross section, that is, at the center of the cross section and at 0.5 mm intervals from the surface to the center (excluding areas less than 0.3 mm from the center).
• the average value of the Vickers hardness measured at one point in the center, 11 points between a position 0.5 mm from the surface and a position 0.5 mm from the center x 4 directions 44 points, a total of 45 points, is defined as the average Vickers hardness H.
• the average value of the hardness measured at one point in the center and 7 points between 0.5 mm and 3.5 mm from the surface (excluding the position 4.0 mm from the surface because it is 0.2 mm from the center) x 4 directions 28 points, a total of 29 points, is defined as the average Vickers hardness H.
• Step wire hardness measurement Using a Vickers testing machine, an indenter is pressed into the cross section of the steel wire with a load of 1 kgf. Starting from a position 0.2 mm deep from the surface (outer surface) of the steel wire, markings are made at 0.2 mm pitch toward the center. Markings are made from four directions at 90° intervals. For plated steel wire, the markings start from a position 0.2 mm deep from the surface of the steel part.
• the average value of the Vickers hardness measured by injecting a point into the steel wire within a depth of 0.2 to 0.5 mm from the surface of the steel wire is defined as the surface Vickers hardness hs, and the average value of the hardness measured by injecting a point into the steel wire within 1 mm from the center is defined as the central Vickers hardness hc.
• the average Vickers hardness is defined as the average value of the Vickers hardness measured over the entire cross section, i.e., at the center of the cross section and at 0.2 mm intervals from the surface toward the center (excluding areas less than 0.2 mm from the center).
• the average value of the hardness measured at one location in the center and 12 locations between 0.2 mm and 2.4 mm from the surface (excluding the location of 2.6 mm from the surface, which is 0.1 mm from the center) x 4 directions 48 locations, for a total of 49 locations, is defined as the average Vickers hardness h.
• Step wire twist test The test is evaluated based on the number of times until the steel wire breaks, and five wires are tested for each test, with the minimum value being evaluated.
• the distance between the chucks is 100 x the wire diameter D.
• the rotation speed is 20 rpm.
• the breakage of the steel wire mentioned here includes not only the breakage of the entire steel wire but also the occurrence of a partial crack in the steel wire. In other words, when a partial crack occurs in the steel wire during the test, the number of twists at that point is used for evaluation.
• the wire to be subjected to the tensile test may be straightened by correction processing.
• the tensile test is performed with the wire length of 340 mm, the chuck distance of 200 mm, and a stroke speed of 10 mm/min.
• the diameter of the wire is measured in two perpendicular directions at the center of the length of the wire using a vernier caliper, and the average value is used.
• the tensile strength is calculated by dividing the maximum load (N) during the tensile test by the cross-sectional area (mm 2 ).
• Tensile tests and diameter measurements for steel wire can be performed in the same way as for wire rods.
• the plating is removed and the tensile test is performed on the steel wire alone. There are two methods for removing the plating: chemical removal, such as immersion in hydrochloric acid, and physical removal, such as grinding.
• the method for producing the wire rod and steel wire according to the present disclosure is not particularly limited, but an example of a suitable production method will be described below.
• a cast slab having the above-mentioned chemical composition is manufactured.
• the slab is obtained by melting the steel in a converter, sufficiently electromagnetically stirring the molten steel, and further reducing the steel during solidification.
• the cast slab is heated to 1200 to 1250° C. and then rolled into a bloom to obtain a steel slab.
• the heating temperature of the steel slab is 1020°C to 1080°C. If the material is heated to a temperature below 1,020° C., the reaction force becomes large, making rolling difficult. On the other hand, if the temperature exceeds 1080°C, the austenite structure will become coarse, and when the steel is immersed in a molten salt as described below, untransformed austenite will remain and martensite may be mixed in.
• the exit temperature of the finish rolling (finish rolling temperature) is set to 900 to 1000°C. It is industrially difficult to set the finish rolling temperature below 900°C. On the other hand, if the finish rolling temperature exceeds 1000° C., the austenite structure becomes coarse, and when the steel sheet is immersed in a molten salt as described below, untransformed austenite may remain and martensite may be mixed in.
• the sheet is cooled to 800°C to 900°C (temperature before coiling) by water cooling or air cooling. If the temperature is less than 800° C., the temperature will drop too low before the molten salt immersion, causing pearlite transformation to start from the surface layer, resulting in softening of the surface layer. If the temperature exceeds 900°C, the austenite structure will become coarse, and when the steel is immersed in a molten salt as described below, untransformed austenite will remain and martensite may be mixed in.
• Cooling is performed before immersion in the molten salt. Before immersion in the molten salt, the material is cooled at a rate of 10° C./sec or more to a temperature of 740° C. to 800° C. (temperature before immersing in the molten salt). Below 740° C., pearlite transformation begins from the surface layer, causing the surface layer to soften. Coarse pearlite reduces the torsional properties. If the temperature exceeds 800°C, the temperature of the molten salt will increase and pearlite transformation will not occur at the target temperature.
• the cooling rate is less than 10° C./sec, the torsional properties deteriorate due to the precipitation of pro-eutectoid cementite.
• the upper limit of the cooling rate is not particularly limited, but may be 50° C./sec or less from a technical viewpoint.
• the wire rod manufactured through the above steps can be subjected to wire drawing to obtain a steel wire having high strength and excellent torsional properties.
• a steel wire with high strength and excellent torsional properties can be manufactured.
• post-treatment such as plating and degreasing treatment may be performed.
• the degreasing treatment and plating treatment with zinc or a zinc alloy are preferably performed within the range of 400 to 530°C. If the temperature is less than 400°C, the steel material becomes hard due to age hardening and the torsional properties deteriorate. If the temperature is 530°C or higher, softening due to spheroidization of cementite becomes significant, resulting in insufficient strength.
• the applications of the steel wire obtained by wire drawing the wire rod according to the present disclosure are not particularly limited, but the wire rod according to the present disclosure is suitable for various applications requiring high strength and torsional properties, such as steel wire for bridge cables and various ropes.
• the wire rod according to the present disclosure is suitable as a material for the steel wire used in these applications.
• a rope (strand) can be obtained by bundling a plurality of steel wires according to the present disclosure.
• a rope can also be obtained by bundling a plurality of plated wires obtained by applying a zinc-containing plating to the steel wire according to the present disclosure.
• wire rod and steel wire of the present disclosure will be described in more detail with reference to examples. However, these examples do not limit the wire rod and steel wire of the present disclosure.
• Example 1 Steel materials having the chemical compositions (unit: mass%) shown in Table 1 were prepared, and wire rods were manufactured by the methods (conditions) shown in Table 2. Note that the notation "-" in Table 1 indicates that the content of the element is at the impurity level, and it can be determined that the element is not substantially contained. The same applies to "-" in Table 4 described later. The remainder of the chemical compositions in Tables 1 and 4 is Fe and impurities.
• the total area ratio of the ferrite structure and the martensite structure in the center, the Vickers hardness, and the tensile strength were measured by the methods described above.
• the wire was drawn to produce a steel wire having a wire diameter of 5.0 mm, that is, a steel wire having a wire drawing strain of 2.06 in the case of a wire diameter of 14.0 mm.
• the Vickers hardness and tensile strength were measured by the above-mentioned methods, and further the number of twists was measured by a torsion test.
• wire rods Nos. 1 to 4 steel wires having high strength (2050 MPa or more) and excellent torsional properties were obtained by wire drawing.
• the ferrite structure or martensite structure was mixed in the wire rod, the area ratio of the ferrite structure or the martensite structure was high, and breakage occurred during wire drawing.
• the surface hardness and average hardness of the wire rod were small, and the tensile strength of the steel wire after wire drawing was insufficient.
• the structure of the wire rod contained a mixture of ferrite and martensite structures, the area ratio of the ferrite and martensite structures was high, and wire breakage occurred during wire drawing.
• No. 10 and 11 the ferrite structure or martensite structure was mixed in the wire rod, the area ratio of the ferrite structure or the martensite structure was high, and breakage occurred during wire drawing.
• the ferrite structure or martensite structure was mixed in the wire rod, the area ratio of the ferrite structure or the martensite structure was high, and wire breakage occurred during
• the surface hardness and average hardness of the wire rod were small, and the tensile strength of the steel wire after wire drawing was insufficient.
• the average hardness was small and the tensile strength of the steel wire after wire drawing was insufficient.
• the difference between the average hardness and the hardness at the center of the wire rod was large due to the temperature difference between the surface layer and the inside of the wire rod, and the torsional properties of the steel wire after wire drawing were insufficient.
• the structure of the wire rod contained a mixture of ferrite and martensite structures, the area ratio of the ferrite and martensite structures was high, and the wire was broken during wire drawing. In No.
• the structure of the wire rod contained a mixture of ferrite and martensite structures, the area ratio of the ferrite and martensite structures was high, and wire breakage occurred during wire drawing.
• Example 2 Steel materials having the chemical compositions (units: mass %) shown in Table 4 were prepared, and wire rods were manufactured under the conditions of manufacturing method A shown in Table 2.
• the total area ratio of the ferrite structure and the martensite structure, the Vickers hardness, and the tensile strength of the produced wire rod were measured by the methods described above.
• the wire was drawn to produce a steel wire with a wire diameter of 5.0 mm.
• the total area ratio of the ferrite structure and the martensite structure in the center, the Vickers hardness, and the tensile strength were measured by the methods described above, and further the number of twists was measured by a torsion test. The measurement results are shown in Tables 5A and 5B.
• the wire rods Nos. 20 to 33 satisfied the requirements of the present disclosure, and steel wires having high strength (2050 MPa or more) and excellent torsional properties were obtained by wiredrawing.
• the C amount was too small, and the tensile strength of the steel wire after wire drawing was insufficient.
• the C content was excessively large, so the average hardness relative to the C content was small, and the torsional properties of the steel wire after wire drawing were insufficient.
• the amount of Si was excessive, so that the area ratio of the ferrite and martensite structures in the wire rod was high, and wire breakage occurred during wire drawing.
• No. 40 the C amount was too small, and the tensile strength of the steel wire after wire drawing was insufficient.
• the C content was excessively large, so the average hardness relative to the C content was small, and the torsional properties of the steel wire after wire drawing were insufficient.
• the amount of Si was excessive, so that the area ratio of the ferrite and martensite structures in the wire rod was high, and
• the area ratio of ferrite and martensite structures in the wire rod was high due to an excessive amount of Mn, and wire breakage occurred during wire drawing.
• the amount of Mo was insufficient, so the average hardness relative to the amount of C was small, and the difference between the average hardness and the hardness at the center and the difference between the hardness at the surface layer and the average hardness were all large, resulting in insufficient tensile strength and torsional properties of the steel wire after wire drawing.
• martensite was mixed in due to the large amount of Mo, the area ratio of the martensite structure in the wire rod was high, the average hardness was small, and breakage occurred during wire drawing.
• the amount of Al was excessive, and breakage occurred during wire drawing.
• the wire rods etc. according to the present disclosure have been described above, but the wire rods etc. according to the present disclosure are not limited to the above-mentioned embodiments and examples.
• the method of manufacturing the wire rods according to the present disclosure is not limited to the method of winding and then immersing in molten salt.
• the scope of the present disclosure also includes a case in which the wire rods according to the present disclosure are manufactured by lead patenting, in which the wire rods are heated and then immersed in a lead bath to create a metal structure, and the wire rods are drawn to manufacture the steel wires according to the present disclosure, and the steel wires are bundled to manufacture a rope (cable).

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Manufacturing & Machinery (AREA)
• Heat Treatment Of Steel (AREA)
• Heat Treatment Of Strip Materials And Filament Materials (AREA)

Priority Applications (5)

Applications Claiming Priority (1)

Publications (1)

Family

ID=92145923

Family Applications (1)

Country Status (5)

Citations (7)

• 2023
  • 2023-02-03 EP EP23919796.5A patent/EP4660331A4/en active Pending
  • 2023-02-03 CN CN202380092981.4A patent/CN120569503A/zh active Pending
  • 2023-02-03 KR KR1020257027563A patent/KR20250138760A/ko active Pending
  • 2023-02-03 JP JP2024574239A patent/JPWO2024161659A1/ja active Pending
  • 2023-02-03 WO PCT/JP2023/003671 patent/WO2024161659A1/ja not_active Ceased

Patent Citations (7)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events