WO2016002413A1 - Matériau de fil pour fil d'acier, et fil d'acier - Google Patents

Matériau de fil pour fil d'acier, et fil d'acier Download PDF

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WO2016002413A1
WO2016002413A1 PCT/JP2015/065863 JP2015065863W WO2016002413A1 WO 2016002413 A1 WO2016002413 A1 WO 2016002413A1 JP 2015065863 W JP2015065863 W JP 2015065863W WO 2016002413 A1 WO2016002413 A1 WO 2016002413A1
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wire
amount
steel wire
pro
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PCT/JP2015/065863
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Japanese (ja)
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友信 石田
智一 増田
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株式会社神戸製鋼所
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Priority to CN201580034203.5A priority Critical patent/CN106661687A/zh
Priority to CA2951799A priority patent/CA2951799A1/fr
Priority to EP18171309.0A priority patent/EP3378964A1/fr
Priority to US15/321,034 priority patent/US20170198375A1/en
Priority to KR1020167036839A priority patent/KR20170013340A/ko
Priority to EP15814624.1A priority patent/EP3165625A4/fr
Priority to MX2016017005A priority patent/MX2016017005A/es
Publication of WO2016002413A1 publication Critical patent/WO2016002413A1/fr

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    • 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
    • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
    • 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 by deformation combined with, or followed by, heat treatment
    • C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
    • C21D8/065—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires of ferrous alloys
    • 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
    • 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
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • 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
    • C22C38/02—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
    • C22C38/08—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
    • C22C38/10—Ferrous alloys, e.g. steel alloys containing cobalt
    • C22C38/105—Ferrous alloys, e.g. steel alloys containing cobalt containing Co and Ni
    • 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
    • C22C38/16—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
    • C22C38/28—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
    • C22C38/40—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
    • 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
    • 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 by deformation combined with, or followed by, heat treatment
    • C21D8/06—Modifying the physical properties 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

Definitions

  • the present invention relates to a wire for steel wire that is a material of a high-strength steel wire used for a wire rope, PC steel wire, and the like, and such a steel wire.
  • a high-strength steel wire rod excellent in bending fatigue characteristics is also useful as a material for a PC (Pressed Concrete) steel wire. Specifically, such a wire for a steel wire is required not to generate low cycle fatigue that occurs when the number of repetitions is 10 4 to 10 5 .
  • Patent Document 1 discloses a technique for improving fatigue strength by finely depositing BN inclusions in steel.
  • Patent Document 2 discloses a technique for obtaining a high-strength wire by controlling the wire structure to a pearlite structure in which the area ratio of pro-eutectoid ferrite is 3% or less by directly performing a melt salt patenting treatment after hot rolling. It is disclosed.
  • the metal structure of the wire is a pearlite structure of 95% or more, and the maximum value and the average value of the pearlite block particle size of the pearlite at the center of the cross section perpendicular to the axial direction of the wire are within a predetermined range.
  • a technique for obtaining a highly ductile wire rod by controlling is disclosed. This technique also discloses that it is useful to adjust the volume fraction of pro-eutectoid ferrite to 2% or less in order to improve the wire drawing workability.
  • Patent Document 1 The characteristic that is a problem in the technique of Patent Document 1 is high cycle fatigue that occurs near the fatigue limit of 10 7 repetitions, and the mechanism is different from that of the low cycle fatigue.
  • products that are exposed to the outside air for a long time, such as wire rope cracks are likely to occur in the surface layer due to oxidation of the surface layer, penetration of hydrogen, friction between strands, etc., far exceeding the original fatigue limit Therefore, it is necessary to take measures to suppress the crack growth.
  • the present invention has been made in view of the circumstances as described above, and its purpose is excellent in low cycle fatigue characteristics and is useful as a material for high-strength steel wires such as wire ropes and PC steel wires, And it is providing the steel wire which can exhibit such a characteristic.
  • the wire rod for steel wire of the present invention that can solve the above-mentioned problems is, in mass%, C: 0.70 to 1.3%, Si: 0.1 to 1.5%, Mn: 0.1 to 1. 5%, N: 0.001 to 0.006%, Al: 0.001 to 0.10%, Ti: 0.02 to 0.20%, B: 0.0005 to 0.010%, P: 0 %, 0.030% or less, S: 0% or more and 0.030% or less, the balance being iron and inevitable impurities, pearlite as the main phase, and the area ratio of proeutectoid ferrite is 1. It has a gist in that it is 0% or less and the average thickness of pro-eutectoid ferrite is 5 ⁇ m or less.
  • the average thickness of pro-eutectoid ferrite means the average value of thickness in the width direction of pro-eutectoid ferrite when the pro-eutectoid ferrite is observed with an optical microscope.
  • the wire for steel wire of the present invention is further mass%, (A) Cr: more than 0%, 1.0% or less and V: more than 0%, 0.5% or less, (B) Ni: more than 0%, 0.5% or less and Nb: at least one kind of more than 0%, 0.5% or less, (C) Co: more than 0%, 1.0% or less, (D) Mo: more than 0%, 0.5% or less and Cu: more than 0%, 0.5% or less, Etc. are also preferable.
  • the content of solute B is preferably 0.0003% or more.
  • the present invention also includes a steel wire having the chemical composition of the steel described above and having a 100,000 times fatigue strength ⁇ satisfying the relationship of the following formula (1) with a tensile strength TS (Tensile Strength). ⁇ > 0.45TS (1)
  • the bending fatigue strength of a steel wire after cold working (drawing) can be reduced by reducing the area ratio of proeutectoid ferrite in the steel wire before drawing and reducing the thickness thereof. It is possible to improve the fatigue characteristics. In particular, it exhibits excellent characteristics against low cycle fatigue caused by repeated stress loading of about 10 4 to 10 5 times.
  • FIG. 1 is a schematic explanatory view showing an implementation status of a four-point bending fatigue test.
  • FIG. 2 is a drawing-substituting micrograph showing an example of the observed pro-eutectoid ferrite grains.
  • the present inventors diligently investigated the factors that influence the low cycle fatigue characteristics in a steel wire material having a metal structure mainly composed of pearlite. As a result, it was found that pro-eutectoid ferrite slightly precipitated in the pearlite structure (hereinafter sometimes abbreviated as “pre-deposition ⁇ ”) promotes the progress of fatigue cracks. In a high carbon steel with a carbon content of 0.70% or more, as shown in FIG. 2 to be described later, the pro-eutectoid ⁇ precipitates in a plate shape at the prior austenite grain boundaries. The present inventors completed the present invention by finding out that excellent low cycle fatigue characteristics can be exhibited by reducing the thickness after setting the content to 1.0% or less.
  • the area ratio of pro-eutectoid ⁇ is preferably 0.8% or less, and more preferably 0.6% or less.
  • B is effective to reduce the area ratio of proeutectoid ⁇ .
  • the area ratio reduction effect of the pro-eutectoid ⁇ is exhibited when B exists as a solid solution B, and the amount deposited as a compound such as BN loses that effect. Therefore, in the steel wire rod of the present invention, it is necessary to control the N content and the B content within appropriate ranges, and it is preferable to manufacture them under manufacturing conditions in which BN hardly precipitates.
  • the average thickness of the pro-eutectoid ⁇ needs to be 5 ⁇ m or less.
  • the average thickness of pro-eutectoid ⁇ is preferably 4 ⁇ m or less, and more preferably 3 ⁇ m or less.
  • Ti inclusions such as TiC are finely dispersed in the steel, particularly in the vicinity of grain boundaries, and a large number of pro-eutectoid ⁇ precipitation nuclei are formed and the nuclei grow. It is effective to suppress this.
  • the steel wire rod according to the present invention needs to have its chemical composition appropriately adjusted from the viewpoint of exerting its basic characteristics when applied to a wire or the like.
  • the chemical component composition including the amounts of B, N, and Ti described above is as follows. Note that “%” in the chemical composition is all “mass%”.
  • C is an element effective for increasing the strength, and the strength of the wire before cold working (steel wire) and the strength of the steel wire after cold working improves as the amount of C increases.
  • the amount of C also affects the amount of precipitation of pro-eutectoid ⁇ . If the amount of C is small, precipitation of pro-eutectoid ⁇ cannot be sufficiently suppressed. Therefore, the C amount is set to 0.70% or more.
  • the amount of C is preferably 0.74% or more, and more preferably 0.78% or more.
  • pro-eutectoid cementite hereinafter sometimes abbreviated as “pre-deposition ⁇ ”
  • the C amount is set to 1.3% or less.
  • the amount of C is preferably 1.2% or less, more preferably 1.1% or less.
  • Si has an action as a deoxidizer and also has an action of improving the strength of the wire.
  • the Si amount was determined to be 0.1% or more.
  • the amount of Si is preferably 0.15% or more, and more preferably 0.20% or more.
  • the Si amount is set to 1.5% or less.
  • the amount of Si is preferably 1.4% or less, and more preferably 1.3% or less.
  • Mn has a deoxidizing effect similar to Si, but has an effect of increasing the toughness and ductility of steel by fixing S in the steel as MnS.
  • the amount of Mn is set to 0.1% or more.
  • the amount of Mn is preferably 0.15% or more, more preferably 0.20% or more.
  • Mn is an element that is easily segregated, and if added excessively, the hardenability of the Mn segregated portion is excessively increased, and a supercooled structure such as martensite may be generated. Therefore, the amount of Mn is set to 1.5% or less.
  • the amount of Mn is preferably 1.4% or less, more preferably 1.3% or less.
  • N (N: 0.001 to 0.006%) N combines with B in the steel to form BN, and the effect of B is lost. Further, N in a solid solution state causes a decrease in torsional characteristics due to strain aging during wire drawing, and if it is remarkable, causes vertical cracks. In order to prevent these harmful effects, the N content is 0.006% or less.
  • the N amount is preferably 0.005% or less, and more preferably 0.004% or less.
  • the N amount is set to 0.001% or more.
  • the N amount is preferably 0.0015% or more, more preferably 0.0020% or more.
  • Al is an effective deoxidizing element. It also has the effect of forming a nitride such as AlN to refine the crystal grains. In order to effectively exhibit such an effect, the Al content is set to 0.001% or more.
  • the amount of Al is preferably 0.002% or more, and more preferably 0.003% or more.
  • Al is set to 0.10% or less.
  • the amount of Al is preferably 0.09% or less, and more preferably 0.08% or less.
  • Ti forms carbides such as TiC and serves to reduce the particle size (thickness) of pro-eutectoid ⁇ . Moreover, it combines with N in the steel to form a nitride such as TiN, and has the function of preventing the twisting characteristics from being lowered by N. In order to effectively exhibit these effects, the Ti content is 0.02% or more.
  • the amount of Ti is preferably 0.03% or more, more preferably 0.04% or more.
  • the amount of Ti becomes excessive, a large amount of Ti-based inclusions such as TiC and TiN are precipitated, increasing the disconnection at the time of wire drawing. Therefore, the Ti content is 0.20% or less.
  • the amount of Ti is preferably 0.15% or less, more preferably 0.10% or less.
  • B (B: 0.0005 to 0.010%, preferably 0.0003% or more as solute B) B functions to prevent the generation of proeutectoid ⁇ and reduce the area ratio.
  • the amount of B needs to be 0.0005% or more.
  • the lower limit of the preferable amount of B is 0.0007% or more, more preferably 0.001% or more.
  • Fe—B compounds such as FeB 2, which are compounds with Fe, precipitate and cause cracking during hot rolling, so the amount of B needs to be 0.010% or less. is there.
  • the amount of B is preferably 0.008% or less, and more preferably 0.006% or less.
  • P 0% or more, 0.030% or less
  • P segregates at the prior austenite grain boundaries, embrittles the grain boundaries, and lowers fatigue strength. Therefore, the smaller the content, the better. Therefore, the P content is 0.030% or less.
  • the amount of P is preferably 0.025% or less, and more preferably 0.020% or less.
  • the amount of P may be 0%, but is usually contained at 0.001% or more.
  • S (S: 0% or more, 0.030% or less) S, like P, segregates at the prior austenite grain boundaries, embrittles the grain boundaries, and lowers fatigue strength. Therefore, the content is preferably as small as possible. Therefore, the S amount is 0.030% or less.
  • the amount of S is preferably 0.025% or less, and more preferably 0.020% or less.
  • the amount of S may be 0%, but is usually contained at 0.001% or more.
  • the basic components of the wire rod of the present invention are as described above, and the balance is substantially iron. However, it is naturally allowed that inevitable impurities brought into the steel depending on the situation of raw materials, materials, manufacturing equipment, etc. are contained in the steel.
  • the wire of the present invention further improves properties such as strength, toughness, ductility, etc.
  • D) Mo: more than 0%, 0.5% or less and Cu: more than 0%, 0.5% or less, Etc. are also preferable.
  • Cr and V are elements useful in increasing the strength (tensile strength) of the wire, and these may be used alone or in combination of two or more.
  • Cr has the effect of increasing the strength and toughness of the wire rod by reducing the pearlite lamella spacing.
  • the Cr content is preferably 0.05% or more.
  • the amount of Cr is more preferably 0.10% or more, and still more preferably 0.15% or more.
  • the Cr amount is preferably 1.0% or less.
  • the amount of Cr is more preferably 0.8% or less, and still more preferably 0.6% or less.
  • V has the effect of improving the strength of the wire by forming carbonitride. Further, in the same manner as Nb, nitride forms excessive solid solution N and nitride after precipitation of AlN and contributes to refinement of crystal grains, and also has an effect of suppressing aging embrittlement by fixing solid solution N.
  • the V amount is preferably 0.01% or more, more preferably 0.02% or more, and further preferably 0.03% or more.
  • V is an expensive element, and even if added excessively, the effect is saturated and economically wasteful, so the V amount is preferably 0.5% or less, more preferably 0.4% or less, More preferably, it is 0.2% or less.
  • Ni and Nb are elements useful for increasing the toughness of the steel wire, and these may be used alone or in combination of two or more.
  • Ni is an element that enhances the toughness of the steel wire after drawing.
  • the Ni content is preferably 0.05% or more, more preferably 0.1% or more, and further preferably 0.2% or more.
  • the Ni content is preferably 0.5% or less, more preferably 0.4% or less, and still more preferably 0.3% or less.
  • Nb like Ti and Al, forms a nitride, contributes to improving the toughness of the steel wire by refining crystal grains, and also has the effect of suppressing aging embrittlement by fixing solid solution N.
  • the Nb content is preferably 0.01% or more, more preferably 0.03% or more, and still more preferably 0.05% or more.
  • Nb is an expensive element, and even if added excessively, the effect is saturated and economically wasteful, so the amount of Nb is preferably 0.5% or less, more preferably 0.4% or less, More preferably, it is 0.3% or less.
  • Co over 0%, 1.0% or less
  • Co has the effect of reducing the formation of pro-eutectoid cementite and making the structure a uniform pearlite structure, particularly when the amount of C is high.
  • the Co content is preferably 0.05% or more, more preferably 0.1% or more, and further preferably 0.2% or more.
  • the Co content is preferably 1.0% or less, more preferably 0.8% or less, and still more preferably 0.6% or less.
  • Mo more than 0%, 0.5% or less and Cu: more than 0%, 0.5% or less
  • Mo is an element that improves the corrosion resistance of the steel wire.
  • the Mo amount is preferably 0.05% or more, more preferably 0.1% or more, and further preferably 0.2% or more.
  • the Mo amount is preferably 0.5% or less, more preferably 0.4% or less, and still more preferably 0.3% or less.
  • Cu is an element that improves the corrosion resistance of steel wires.
  • the amount of Cu is preferably 0.05% or more, more preferably 0.08% or more, and further preferably 0.10% or more.
  • the amount of Cu is preferably 0.5% or less, more preferably 0.4% or less, and still more preferably 0.3% or less.
  • Mo and Cu may be contained in combination of one or two kinds.
  • the wire rod before cold drawing is usually produced by melting, split-rolling and hot-rolling steel with appropriately controlled chemical components, and further performing patenting treatment as necessary.
  • the contents of Ti, B and N are within the above ranges. It is important to appropriately control the precipitation behavior of TiC and BN while appropriately controlling.
  • the slab is heated to 1200 ° C. or higher to decompose the coarse TiC precipitated during casting.
  • the heating temperature is lower than 1200 ° C., coarse TiC remains in the wire, and the thickness of the pro-eutectoid ⁇ cannot be sufficiently reduced, so that the fatigue strength is lowered.
  • This heating temperature is more preferably 1250 ° C. or more, and further preferably 1300 ° C. or more. However, if the heating temperature becomes too high, melting of the wire material occurs, so the temperature is usually set to about 1400 ° C.
  • the coarse BN in the billet is sufficiently decomposed, and then sufficiently cooled by water cooling after rolling, and rolled material ( It is preferable to control the mounting temperature of the wire) on the laying head to 800 to 1000 ° C.
  • the mounting temperature is more preferably 980 ° C. or lower, and further preferably 950 ° C. or lower.
  • the mounting temperature is preferably 800 ° C. or higher.
  • the mounting temperature is more preferably 820 ° C. or higher, and further preferably 850 ° C. or higher.
  • the strain rate in the final four passes of rolling it is preferable to set the strain rate in the final four passes of rolling to 0.5 second ⁇ 1 or more, to refine crystal grains by dynamic recrystallization, and to precipitate fine TiC. . If the strain rate is less than 0.5 sec ⁇ 1 , TiC cannot be sufficiently refined, and the average thickness of proeutectoid ⁇ cannot be sufficiently reduced.
  • the strain rate at this time is more preferably 0.8 sec ⁇ 1 or more, and further preferably 1.0 sec ⁇ 1 or more. However, from the viewpoint of equipment load, the strain rate is usually preferably 5 seconds -1 or less.
  • strain rate V ⁇ is equal to the cross-sectional area S 0 (m 2 ) before entering the first roll, four rolls before the final pass, and the cross-sectional area S 4 (m 2 ) after passing the final pass.
  • total passage time (rolling time) t (seconds) of 4 passes can be expressed by the following equation (2).
  • V ⁇ ⁇ ln (S 0 / S 4 ) ⁇ / t (2)
  • the wire After mounting, the wire is cooled on a cooling conveyor, and pearlite transformation is caused during this cooling, but it is preferable to rapidly cool the pearlite transformation at an average cooling rate of 5 ° C./second or more.
  • the average cooling rate at this time is slow, the pro-eutectoid ⁇ is likely to precipitate and become coarse at high temperatures, and the thickness of the pro-eutectoid ⁇ may not be sufficiently reduced.
  • the average cooling rate is less than 5 ° C./second, a structure with extremely rough lamellar spacing called “corse pearlite” is deposited locally, which may reduce the drawability.
  • the temperature of a wire may be measured and the point (inflection point) where a cooling curve may change by transformation heat_generation
  • the average cooling rate is more preferably 10 ° C./second or more, and further preferably 15 ° C./second or more.
  • a preferable upper limit of the average cooling rate is 100 ° C./second or less, and more preferably 50 ° C./second or less.
  • the wire obtained as described above can be used as a steel wire by drawing (cold working) as it is, but it may be subjected to a patenting treatment before the drawing. By performing such a patenting process before wire drawing, the strength of the wire can be increased and the variation in strength can be reduced.
  • the wire material structure is subjected to a patenting treatment after drawing to some extent from the rolled material, and the wire material structure is converted into an unprocessed pearlite. It is also useful to perform further wire drawing after returning to the tissue.
  • a patenting treatment by performing a patenting treatment, the pro-eutectoid ⁇ obtained during hot rolling is lost, but if finely precipitated TiC and a sufficient amount of solute B are secured, general patenting can be performed.
  • An appropriate area ratio and average thickness of pro-eutectoid ⁇ can be obtained depending on processing conditions.
  • the heating temperature when the patenting treatment is performed (hereinafter, this temperature may be referred to as “reheating temperature”) is preferably about 900 to 1000 ° C., more preferably 920 ° C. or more and 980 ° C. or less.
  • the reheating temperature is preferably 900 ° C. or more from the viewpoint of preventing the remaining of insoluble carbides and making the structure completely austenitic.
  • TiC becomes coarse or solute B is N.
  • the area ratio and average thickness of a predetermined pro-eutectoid ⁇ may not be obtained.
  • the holding temperature in the patenting treatment is preferably about 530 to 600 ° C., more preferably 550 ° C. or higher and 580 ° C. or lower.
  • the wire rod according to the present invention has a sufficiently reduced amount of pro-eutectoid ⁇ that promotes the generation and propagation of fatigue cracks, and the thickness thereof is controlled to be small.
  • Products such as wire ropes and PC steel wires that use all or part of the wires have better fatigue properties than normal products.
  • the tensile strength and fatigue strength are in a proportional relationship, but the steel wire manufactured from the wire of the present invention has a 100,000 times fatigue strength ⁇ satisfying the relationship of the following formula (1) with the tensile strength TS.
  • the present invention also includes such a steel wire.
  • the present invention also includes products such as wire ropes manufactured using all or part of such steel wires. ⁇ > 0.45TS (1)
  • the area ratio of proeutectoid ⁇ was measured by embedding the collected sample in resin or the like, mirror polishing, observing with an optical microscope using a mixed solution of trinitrol phenol and ethanol, and measuring the area ratio by image analysis. .
  • the part whitened by the above-mentioned corrosive liquid is the pro-eutectoid ⁇ .
  • the diameter of the wire was D
  • the D / 4 portion of the cross section was considered as the representative structure, and images were taken at a magnification of 400 times to evaluate a total of 5 fields of view.
  • the “area ratio of pro-eutectoid ⁇ ” shown in Table 4 below shows the average value.
  • a cross section points out a surface perpendicular
  • the area ratio of pearlite was also measured by this method.
  • P indicates that the pearlite structure is 95 area% or more, that is, pearlite is the main phase.
  • P + ⁇ ” or P + ⁇ indicates a structure in which the pearlite structure is less than 95 area%, and in addition to the pearlite structure, ferrite ( ⁇ ) and cementite ( ⁇ ) are mixed.
  • the amount of solute B was evaluated by measuring the electrolytic extraction residue. Electrolytic extraction residue measurement using a 10% acetylacetone solution was carried out, and the amount of compound type B in the residue was measured by a bromester method using a mesh with an opening of 0.1 ⁇ m. The solid solution B amount was determined by subtracting the compound type B amount from the total B amount in the steel. The results are shown in Table 4 below. The sample used for the bromester method was 3 g. Moreover, since the amount of solid solution B does not change unless it receives a heat history of 900 ° C. or higher, the amount of solid solution B may be investigated with a steel wire after cold working.
  • the obtained wire coil was drawn to produce a steel wire (wire), and a tensile test, a twisting property evaluation, and a fatigue property evaluation were performed.
  • Table 5 shows the reduction in area during wire drawing and the wire diameter of the steel wire obtained by wire drawing.
  • the twisting property was evaluated based on the twist value (number of times of rupture twist) required for rupture after conducting a twist test.
  • the twist value was normalized by converting the distance between the chucks (test wire length) to 100 times the wire diameter d (100d). Moreover, the normal fracture surface and the vertical crack were discriminated by the fracture surface observation, and even one of the five vertical cracks was described as “with vertical crack” in Table 5 below.
  • the fatigue characteristics were evaluated by repeatedly performing a four-point bending fatigue test using a jig that supported four points.
  • 1 is a test piece (wire)
  • 2 is a direction in which repeated stress is applied
  • ⁇ is a support point.
  • the maximum stress amplitude in the passed sample was defined as 100,000 times fatigue strength ⁇ .
  • the 100,000 times fatigue strength ⁇ is shown in Table 5 below.
  • the stress waveform was a sine wave and the frequency was 10 Hz.
  • test No. for 1-3, 10-21 the chemical component composition and the metal structure (perlite area ratio, area ratio of pro-eutectoid ⁇ , average thickness of pro-eutectoid ⁇ ) are all within the ranges specified by the present invention.
  • a tensile strength standard, for example, 1620 to 1770 MPa when the wire diameter is 7.0 mm
  • “Piano wire type B” described in G 3522 (1991) the relationship of the above equation (1) is obtained.
  • a steel wire (wire) that achieves satisfactory fatigue strength is obtained.
  • test no. Examples 4 to 9 and 22 to 27 are examples in which any of the requirements of the present invention is not satisfied. Of these, test no. As shown in Table 2, since the heating temperature at the time of the block rolling was low as shown in Table 2, coarse TiC was precipitated, and as shown in Table 4, the average thickness of proeutectoid ⁇ was increased and the fatigue strength was lowered.
  • Test No. No. 22 is an example using the steel type P having a small amount of C. As shown in Table 4, both the area ratio and the average thickness of the pro-eutectoid ⁇ were increased, and the twisting characteristics and fatigue strength were lowered.
  • Test No. No. 23 is an example using the steel type Q having a large amount of C. Since a large amount of proeutectoid cementite was precipitated, it was broken during wire drawing.
  • Test No. No. 24 is an example using the steel type R with a small amount of Ti.
  • the amount of TiC was small, the average thickness of proeutectoid ⁇ was increased, and the fatigue strength was lowered.
  • Test No. No. 25 is an example using the steel type S with a large amount of Ti, and a large amount of Ti-based inclusions were precipitated and disconnected during wire drawing.
  • Test No. No. 26 is an example using the steel type T having a large amount of B, and a sample was not obtained due to disconnection during hot rolling.
  • Test No. 27 is an example using the steel type U with a small amount of B.
  • the area ratio of the pro-eutectoid ⁇ was increased, and the twisting characteristics and fatigue strength were reduced.
  • FIG. 2 shows test No. 1 as an example.
  • 3 is a drawing-substituting micrograph showing an example of pro-eutectoid ⁇ observed in FIG.
  • An ellipse 3 shown in FIG. 2 indicates the deposition position of proeutectoid ⁇ . From FIG. 2, it can be seen that the pro-eutectoid ⁇ is precipitated in a plate shape, and the “width direction” and “length direction” of the grains can be easily distinguished.

Abstract

La présente invention concerne un matériau de fil pour fil d'acier, ledit matériau de fil possédant d'excellentes caractéristiques de fatigue oligocyclique et étant utile en tant que matériau brut pour fil d'acier à haute résistance pour câble d'acier, fil d'acier PC, ou analogue. L'invention concerne également un fil d'acier qui peut présenter lesdites caractéristiques. L'invention a également trait à un matériau de fil pour fil d'acier selon la présente invention qui contient, en % en masse, 0,70 % à 1,3 % de C, 0,1 % à 1,5 % de Si, 0,1 % à 1,5 % de Mn, 0 001 % à 0 006 % de N, 0,001 % à 0,10 % de Al, 0,02 % à 0,20 % de Ti, 0,0005 % à 0 010 % de B, 0 % à 0 030 % de P, et de 0 % à 0 030 % de S, le reste étant du fer et des impuretés inévitables, la phase principale étant de la perlite, le rapport surfacique de ferrite proeutectoïde étant égale ou inférieure à 1,0 %, et l'épaisseur moyenne de la ferrite proeutectoïde étant de 5 µm ou moins.
PCT/JP2015/065863 2014-07-01 2015-06-02 Matériau de fil pour fil d'acier, et fil d'acier WO2016002413A1 (fr)

Priority Applications (7)

Application Number Priority Date Filing Date Title
CN201580034203.5A CN106661687A (zh) 2014-07-01 2015-06-02 钢丝用线材和钢丝
CA2951799A CA2951799A1 (fr) 2014-07-01 2015-06-02 Materiau de fil pour fil d'acier, et fil d'acier
EP18171309.0A EP3378964A1 (fr) 2014-07-01 2015-06-02 Tige de fil métallique pour fil d'acier et fil d'acier
US15/321,034 US20170198375A1 (en) 2014-07-01 2015-06-02 Wire rod for steel wire, and steel wire
KR1020167036839A KR20170013340A (ko) 2014-07-01 2015-06-02 강선용 선재 및 강선
EP15814624.1A EP3165625A4 (fr) 2014-07-01 2015-06-02 Matériau de fil pour fil d'acier, et fil d'acier
MX2016017005A MX2016017005A (es) 2014-07-01 2015-06-02 Barra de alambre para alambre de acero, y alambre de acero.

Applications Claiming Priority (2)

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JP2014-136222 2014-07-01
JP2014136222A JP2016014168A (ja) 2014-07-01 2014-07-01 鋼線用線材および鋼線

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CA (1) CA2951799A1 (fr)
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EP3336205A1 (fr) * 2016-12-16 2018-06-20 Posco Fil d'acier à haute résistance et son procédé de fabrication

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JP6528920B2 (ja) * 2017-05-18 2019-06-12 日本製鉄株式会社 線材、及び鋼線の製造方法
CN107630171A (zh) * 2017-09-22 2018-01-26 张家港沙工科技服务有限公司 一种起重机用抗拉型金属吊绳
KR102079550B1 (ko) * 2018-08-09 2020-02-21 주식회사 포스코 킹크 특성이 우수한 강선, 강선용 선재 및 이들의 제조방법
KR102059095B1 (ko) * 2019-07-02 2019-12-24 홍덕산업(주) 직선 품질이 우수한 강선 및 이의 제조방법
JP7440758B2 (ja) * 2020-03-30 2024-02-29 日本製鉄株式会社 線材及び鋼線
CN111974798B (zh) * 2020-07-24 2022-05-27 柳州钢铁股份有限公司 提高盘条表面氧化铁皮厚度的方法
CN116356588B (zh) * 2023-04-06 2024-01-19 任丘市海峰电力科技有限公司 一种钢绞线制备方法

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EP3165625A4 (fr) 2017-11-22
EP3378964A1 (fr) 2018-09-26
KR20170013340A (ko) 2017-02-06
CN106661687A (zh) 2017-05-10
JP2016014168A (ja) 2016-01-28
CA2951799A1 (fr) 2016-01-07
EP3165625A1 (fr) 2017-05-10
MX2016017005A (es) 2017-05-12
CN109576448A (zh) 2019-04-05

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