CN105612269A - Wire rod, hypereutectoid bainite steel wire, and method for manufacturing same - Google Patents

Wire rod, hypereutectoid bainite steel wire, and method for manufacturing same Download PDF

Info

Publication number
CN105612269A
CN105612269A CN201480055078.1A CN201480055078A CN105612269A CN 105612269 A CN105612269 A CN 105612269A CN 201480055078 A CN201480055078 A CN 201480055078A CN 105612269 A CN105612269 A CN 105612269A
Authority
CN
China
Prior art keywords
wire rod
wire
bath
molten salt
salt bath
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
CN201480055078.1A
Other languages
Chinese (zh)
Other versions
CN105612269B (en
Inventor
多田达诚
高桥幸弘
西川宜孝
平上大辅
真锅敏之
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nippon Steel Corp
Original Assignee
Nippon Steel Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nippon Steel Corp filed Critical Nippon Steel Corp
Publication of CN105612269A publication Critical patent/CN105612269A/en
Application granted granted Critical
Publication of CN105612269B publication Critical patent/CN105612269B/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

Links

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
    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C21D1/19—Hardening; Quenching with or without subsequent tempering by interrupted quenching
    • C21D1/20—Isothermal quenching, e.g. bainitic hardening
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/34—Methods of heating
    • C21D1/44—Methods of heating in heat-treatment baths
    • C21D1/46—Salt baths
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/34—Methods of heating
    • C21D1/44—Methods of heating in heat-treatment baths
    • C21D1/48—Metal baths
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/56—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering characterised by the quenching agents
    • C21D1/607—Molten salts
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/008—Heat treatment of ferrous alloys containing Si
    • 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
    • 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
    • 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
    • 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
    • C21D9/54—Furnaces for treating strips or wire
    • C21D9/56—Continuous furnaces for strip or wire
    • C21D9/58—Continuous furnaces for strip or wire with heating by baths
    • 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
    • C22C38/002—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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • 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
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel 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
    • C22C38/40—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
    • 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
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel 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
    • C22C38/40—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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
    • 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
    • C21D2211/002—Bainite

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)

Abstract

A wire rod according to the present invention includes a predetermined chemical composition, wherein a structure includes 90 to 100 area% of bainite, when 8 test pieces having a length of 400mm are produced by dividing the wire rod having a length of 3200mm into 8 pieces having an equal length, an average tensile strength TS of each of the test pieces satisfies a relation of '[TS] <= 810*[C]+475' in terms of N/mm<2>, a difference of tensile strength between a maximum value and a minimum value of each of the test pieces is 50N/mm<2> or less, and an average reduction in area RA of each of the test pieces satisfies a relation of '[RA] >= -0.083*[TS]+154' in terms of %.

Description

Wire rod, hypereutectoid bainite steel wire and their manufacture method
Technical field
The present invention relates to wire rod that the hypereutectoid bainite steel wire of wire drawing characteristic and delayed fracture resistance characteristics excellence uses, by thisThe hypereutectoid bainite steel wire that wire rod is manufactured and their manufacture method.
The application is based on advocating priority No. 2013-211365 in the Patent of Japanese publication on October 8th, 2013, in itAppearance is incorporated herein.
Background technology
Wire rod is the material of the various mechanical parts such as steel wire. Manufactured various mechanical parts by wire rod (hereinafter referred to as finallyGoods) situation under, conventionally wire rod is carried out machining and the annealing such as Wire Drawing. The tensile strength of end article is mainly subject toOne-tenth to wire rod is grouped into, the particularly impact of the C content of wire rod. When on the other hand, the metal structure of wire rod is due to annealingPhase transformation meeting changes. Therefore, manufacturing by the operation that comprises annealing at end article, the metal structure of wire rodCan not affect the tensile strength of end article. Due to above reason, manufacture by the operation that comprises annealing at end articleSituation under, the one-tenth of wire rod is grouped into need to be corresponding with the needed tensile strength of end article.
On the other hand, no matter the tensile strength of end article is how, all preferred low persons of tensile strength of wire rod. Tensile strengthThe machining property of high wire rod and wire drawing characteristic are low. And then, due to the high wire rod of tensile strength to delayed fracture (by hydrogen embrittlementThe fracture causing) sensitiveness high, so its manufacture, keeping and carry time easily lose. Particularly the C content of wire rod is0.8 quality % is when above (, when exceeding eutectoid point thereby wire rod and be hypereutectoid steel due to the C content of wire rod), there is wire rod pairThe sensitiveness of delayed fracture (hydrogen embrittlement) uprises such problem. Consequently, for keeping and carry and by manufacture after wire rodWhen bundling becomes coiled material shape, the stress during sometimes because of bundling causes wire rod to be lost. Wire rod lose the work efficiency that adds that can cause wire rodThe reduction of rate. And then, when the needed length of Length Ratio end article of the wire rod of losing in short-term, cannot be using this wire rod asThe materials'use of whole goods.
In order to prevent from resulting from losing of delayed fracture (hydrogen embrittlement), consider mitigation bundling condition, for example reduced bundling lineThe power of material etc. But, owing to relaxing bundling condition, can cause coiled material keeping, coiled material transporting and while processing coiled materialSecurities etc. suffer damage.
For example, if be grouped into, make C content to reduce the tensile strength of wire rod by adjusting the one-tenth of wire rod, with delayFracture and the relevant problem of machining property are resolved. But, as described above, the one-tenth of wire rod be grouped into must with final systemThe needed tensile strength of product is corresponding. Therefore, cannot adopt adjustment that the one-tenth of wire rod is grouped into as preventing delayed fractureMeans.
Heat-treat condition when changing the manufacture of wire rod, can make the tensile strength of wire rod reduce. In the past excessively commonThe metal structure of analysing wire rod (C content exceedes the wire rod of eutectoid point) is mainly made up of pearlite. The system of hypereutectoid wire rod in the pastMaking method comprises and steel rolling is obtained to the operation of wire rod and by operation cooling this wire rod. In the time of cooling operation, wire rodMetal structure become pearlite. In this manufacture method, if first the wire rod after rolling is heated to austenitic temperature region,Then cooling with slow cooling velocity, can make the tensile strength of wire rod reduce. But, C content is being exceeded to eutectoidThe manufacture method of the wire rod of point is suitable in the slow situation of creating conditions of cooling velocity, not only generates more pearlite when coolingAnd generate the more cementite of just analysing. Just analyse the processability deterioration that cementite can make wire rod. Therefore, cannot adopt the wire rod that slows downThe method of cooling velocity is as the means that prevent delayed fracture.
In view of above situation, it is strong as reducing tension that people of the present invention have studied the adjustment of the metal structure that adopts wire rodThe means of degree. As described above, in the time that end article is manufactured by the operation that comprises annealing, the metal structure of wire rod can be not rightThe tensile strength of end article impacts. Utilize the common wire rod that prior art obtains mainly to be formed by pearlitic structrure,Such wire rod is called as pearlitic wires. On the other hand, the known wire rod (bainite wire rod) taking bainite as Main TissuesWire drawing excellent compared with pearlitic wires (for example, with reference to patent documentation 1～7). In addition, C content exceedes the excessively common of eutectoid pointAnalyse the tensile strength of bainite wire rod than the tensile strength of pearlitic wires with the C content identical with this bainite wire rodLow. For example, people of the present invention recognize that C content is that the average tensile strength of 1.1% bainite wire rod is 1.1% than C contentThe low 200～300MPa of average tensile strength of pearlitic wires. By the metal structure of wire rod is made to bainite, no matter rightHow (no matter to the desired C content of steel wire how) of the desired tensile strength of end article after annealing, all can make lineThe tensile strength of material reduces, and can reach thus the raising of wire drawing characteristic and the inhibition of delayed fracture.
But there is the easily such problem of inequality of tensile strength in bainite wire rod. The shape of the tensile strength inequality of wire rodState refers in the multiple positions in 1 wire rod and measures tensile strength, the state of these measured value inequalities. Wire rodWhen tensile strength is uneven, in the high position of tensile strength, the sensitiveness of delayed fracture (hydrogen embrittlement) is improved, generation is lost. EnterAnd when the tensile strength of wire rod is uneven, the processability inequality of wire rod, so that the machining of wire rod becomes is difficult. Patent documentation 1～In 7, the manufacture method of bainite wire rod is disclosed. But people of the present invention recognize: based on specifically disclosed in these documentsWhen manufacture method is manufactured bainite wire rod, the tensile strength of wire rod is uneven widely. People of the present invention are by by above-mentioned systemFirst the wire rod that making method obtains cuts into the length of 3200mm. Then people of the present invention, by by these wire rod 8 deciles, make 8Root has the test film of the length of 400mm, and these test films have been carried out to tension test. In the tensile strength of these test filmsPoor (hereinafter referred to as the uneven amplitude of tensile strength) of maximum and minimum of a value exceedes 100N/mm2. On the other hand, the inventorThe result studied know, the uneven amplitude of the tensile strength of wire rod exceedes 50N/mm2Wire rod be difficult to for industrial profitWith.
Prior art document
Patent documentation
Patent documentation 1: Japanese kokai publication hei 05-117762 communique
Patent documentation 2: Japanese kokai publication hei 06-017190 communique
Patent documentation 3: Japanese kokai publication hei 06-017191 communique
Patent documentation 4: Japanese kokai publication hei 06-017192 communique
Patent documentation 5: Japanese kokai publication hei 06-073502 communique
Patent documentation 6: Japanese kokai publication hei 06-330240 communique
Patent documentation 7: Japanese kokai publication hei 08-003639 communique
Summary of the invention
Invent technical problem to be solved
As described above, utilize pearlitic wires that prior art obtains because tensile strength is high, so there is easy productThe such problem of raw delayed fracture. Reduce tensile strength in view of by pearlite line by reducing the C content of this pearlitic wiresThe specification that requires of the end article that material obtains is difficult. On the other hand, in the manufacture method of this pearlitic wires, by subtractingFew cooling velocity reduces tensile strength because meeting increases the amount of just analysing cementite, so not preferred. Just analyse the increasing of the carburizing scale of constructionConference reduces the machining property of wire rod. In addition, utilize bainite wire rod that prior art obtains, particularly C content exceedesThe hypereutectoid bainite wire rod of eutectoid point has the easily such problem of inequality of tensile strength. The inequality of tensile strength can make to postponeThe occurrence frequency of fracture rises, and machining property is reduced.
Problem of the present invention is, by the metal structure of wire rod is mainly made to bainite, to carry out C content and exceed eutectoidLow tensile strength and the high ductibility of the wire rod of point, wire drawing characteristic and the delayed fracture resistance characteristics of raising wire rod. And then, thisThe problem of invention is the inequality of the tensile strength that suppresses wire rod. And, the object of the present invention is to provide and solve these problemsWire rod, use the hypereutectoid bainite steel wire of this wire rod manufacture and for stably manufacturing their manufacture method.
For the means of technical solution problem
People of the present invention find, by just analysing the inhibition of cementite and the low-intensity of wire rod based on generating to take into accountThe bainite structure of changing create conditions to manufacture wire rod, can solve above-mentioned problem.
The present invention carries out based on above-mentioned opinion, and its purport is as described below.
(1) wire rod of a mode of the present invention has following compositions composition: in unit mass, % contains C: exceed0.80～1.20％、Si：0.10～1.50％、Mn：0～1.00％、P：0～0.02％、S：0～0.02％、Cr：0～1.00％、Ni：0～1.00％、Cu：0～1.00％、Mo：0～0.50％、Ti：0～0.20％、Nb：0～0.20％、V：0～0.20%, B:0～0.0050%, Al:0～0.10% and Ca:0～0.05%, remainder comprise Fe and impurity, wherein, and goldBelong to the bainite that tissue comprises 90～100 area %, be divided into 8 equal length by the wire rod that is 3200mm by lengthUnit is manufactured in the situation of the test film that 8 length are 400mm, and the mean value TS of the tensile strength of each above-mentioned test film is with listPosition N/mm2Meter meets following formula 1, and the maximum in the each above-mentioned tensile strength of each above-mentioned test film and the difference of minimum of a value are 50N/mm2Below, the mean value RA of the drawing value of each above-mentioned test film meets following formula 2 in the % of unit.
[TS]≤810 × [C]+475 (formula 1)
[RA] >=-0.083 × [TS]+154 (formula 2)
Wherein, [C] is the C content of the above-mentioned wire rod in unit mass %, and [TS] is with the N/mm of unit2The above-mentioned of meter resistsThe above-mentioned mean value TS of tensile strength, [RA] is the above-mentioned mean value RA of the above-mentioned drawing value in the % of unit.
(2) the hypereutectoid bainite steel wire of another mode of the present invention can be by entering the wire rod above-mentioned (1) Suo ShuRow Wire Drawing obtains.
(3) manufacture method of the wire rod of a mode of the present invention is the manufacture method of above-mentioned (1) described wire rod, its toolStandby following operation: billet rolling is obtained to the operation of wire rod, above-mentioned steel billet has following compositions composition: in unit mass %Contain C: exceed 0.80～1.20%, Si:0.10～1.50%, Mn:0～1.00%, P:0～0.02%, S:0～0.02%,Cr：0～1.00％、Ni：0～1.00％、Cu：0～1.00％、Mo：0～0.50％、Ti：0～0.20％、Nb：0～0.20%, V:0～0.20%, B:0～0.0050%, Al:0～0.10% and Ca:0～0.05%, remainder comprise Fe andImpurity; The above-mentioned wire rod of 850～1050 DEG C is immersed in the 1st molten salt bath or molten lead bath of 350～450 DEG C, then willThe operation that above-mentioned wire rod takes out from above-mentioned the 1st molten salt bath or molten lead bath; Moment in 5 seconds from above-mentioned taking-up,And the t of the beginning of the bainitic transformation of above-mentioned wire rodsBefore second～tsIn moment after second, above-mentioned wire rod is immersed in to 530～600 DEG CThe 2nd molten salt bath or molten lead bath in operation; With by above-mentioned wire rod after above-mentioned bainitic transformation finishes completely from above-mentionedThe operation of taking out in the 2nd molten salt bath or molten lead bath.
ts＝0.05×tComplete(formula 3)
tCompleteBe illustrated in the in the situation that above-mentioned wire rod being continued to dipping in above-mentioned the 1st molten salt bath or molten lead bath, with listThe bainitic transformation from above-mentioned wire rod of bps meter starts till the time finishing.
(4), according to the manufacture method of the wire rod above-mentioned (3) Suo Shu, wherein, above-mentioned wire rod is submerged in above-mentioned the 1st fuse saltMoment and above-mentioned wire rod in bath or molten lead bath were submerged between the moment in above-mentioned the 2nd molten salt bath or molten lead bathElapsed time can be 10～40 seconds.
(5), according to the manufacture method of the wire rod above-mentioned (3) Suo Shu, wherein, can come by the backheat that detects above-mentioned wire rodJudge the above-mentioned moment that the above-mentioned bainitic transformation in the above-mentioned wire rod in above-mentioned the 1st molten salt bath or molten lead bath starts.
(6) manufacture method of the hypereutectoid bainite steel wire of another mode of the present invention is above-mentioned (2) described excessively commonAnalyse the manufacture method of bainite steel wire, it possesses following operation: billet rolling is obtained to the operation of wire rod, above-mentioned steel billet hasFollowing compositions composition: % contains C in unit mass: exceed 0.80～1.20%, Si:0.10～1.50%, Mn:0～1.00%, P:0.02% is following, S:0.02% following, Cr:0～1.00%, Ni:0～1.00%, Cu:0～1.00%, Mo:0～0.50%, Ti:0～0.20%, Nb:0～0.20%, V:0～0.20%, B:0～0.0050%, Al:0～0.10% andCa:0～0.05%, remainder comprise Fe and impurity; The wire rod of 850～1050 DEG C is immersed in to 350～450 DEG C the 1st moltenMelt in salt bath or molten lead bath the operation of then above-mentioned wire rod being taken out from above-mentioned the 1st molten salt bath or molten lead bath; FromAbove-mentioned taking-up plays 5 seconds t with the beginning of the bainitic transformation of interior moment and above-mentioned wire rodsBefore second～tsMoment after second, willAbove-mentioned wire rod is immersed in the operation in the 2nd molten salt bath or the molten lead bath of 530～600 DEG C; By above-mentioned wire rod at above-mentioned Bei ShiThe operation of taking out from the 2nd molten salt bath or molten lead bath after body phase transformation finishes completely; With to from above-mentioned the 2nd molten salt bath or moltenMelt the above-mentioned wire rod taking out in lead bath and implement the operation of Wire Drawing.
ts＝0.05×tComplete
tCompleteBe illustrated in the in the situation that above-mentioned wire rod being continued to dipping in above-mentioned the 1st molten salt bath or molten lead bath, with listThe bainitic transformation from above-mentioned wire rod of bps meter starts till the time finishing.
(7) according to the manufacture method of the hypereutectoid bainite steel wire above-mentioned (6) Suo Shu, wherein, above-mentioned wire rod is submerged inTime in above-mentioned the 1st molten salt bath or molten lead bath can be 10～40 seconds.
(8) according to the manufacture method of the hypereutectoid bainite steel wire above-mentioned (6) Suo Shu, wherein, can be above-mentioned by detectingThe backheat of wire rod is judged what the above-mentioned bainitic transformation in the above-mentioned wire rod in above-mentioned the 1st molten salt bath or molten lead bath startedThe above-mentioned moment.
(9) manufacture method of the hypereutectoid bainite steel wire described in another mode of the present invention is that above-mentioned (2) are describedThe manufacture method of hypereutectoid bainite steel wire, it possesses following operation: to drawing by the wire rod that billet rolling is obtainedSilk processing and obtain the operation of steel wire, above-mentioned steel billet has following compositions composition: in unit mass, % contains C: exceed 0.80～1.20％、Si：0.10～1.50％、Mn：0～1.00％、P：0～0.02％、S：0～0.02％、Cr：0～1.00％、Ni：0～1.00％、Cu：0～1.00％、Mo：0～0.50％、Ti：0～0.20％、Nb：0～0.20％、V：0～0.20％、B:0～0.0050%, Al:0～0.10% and Ca:0～0.05%, remainder comprise Fe and impurity; By 850～1050 DEG CAbove-mentioned steel wire is immersed in the 1st molten salt bath or molten lead bath of 350～450 DEG C, then by above-mentioned steel wire from above-mentioned the 1st meltingThe operation of taking out in salt bath or molten lead bath; Moment in 5 seconds from above-mentioned taking-up and the bainitic transformation of above-mentioned steel wireThe t of beginningsBefore second～tsIn moment after second, above-mentioned steel wire is immersed in to the 2nd molten salt bath or the molten lead bath of 530～600 DEG CIn operation; With by above-mentioned steel wire after above-mentioned bainitic transformation finishes completely from above-mentioned the 2nd molten salt bath or molten lead bathThe operation of taking out.
ts＝0.05×tComplete
tCompleteBe illustrated in the in the situation that above-mentioned wire rod being continued to dipping in above-mentioned the 1st molten salt bath or molten lead bath, with listThe bainitic transformation from above-mentioned wire rod of bps meter starts till the time finishing.
(10) according to the manufacture method of the hypereutectoid bainite steel wire above-mentioned (9) Suo Shu, wherein, above-mentioned steel wire is submerged inMoment in above-mentioned the 1st molten salt bath or molten lead bath and above-mentioned steel wire are submerged in above-mentioned the 2nd molten salt bath or molten lead bathIn moment between elapsed time can be 10～40 seconds.
(11) according to the manufacture method of the hypereutectoid bainite steel wire above-mentioned (9) Suo Shu, wherein, can be above-mentioned by detectingThe backheat of steel wire is judged what the above-mentioned bainitic transformation in the above-mentioned steel wire in above-mentioned the 1st molten salt bath or molten lead bath startedThe above-mentioned moment.
(12) according to the manufacture method of the hypereutectoid bainite steel wire described in any one in above-mentioned (9)～(11), wherein, canFurther implement the operation of Wire Drawing to possess above-mentioned steel wire to taking out from above-mentioned the 2nd molten salt bath or molten lead bath.
Invention effect
According to the present invention, can obtain with pearlitic wires be in the past in a ratio of low tensile strength and for high ductibility, withPast bainite wire rod is compared the little wire rod of uneven amplitude of tensile strength. In the time of bundling wire rod of the present invention or in the present inventionWire rod by under the state of bundling, that loses is inhibited. And then, the processability of wire rod of the present invention and this wire rod is enteredRow Wire Drawing and the processability of the steel wire of the present invention that obtains is good. Therefore, according to the present invention, can provide wire drawing characteristic andThe wire rod that the hypereutectoid bainite steel wire of delayed fracture resistance characteristics excellence is used, the hypereutectoid bainite steel wire that uses this wire rod to manufactureAnd stably manufacture their manufacture method.
Brief description of the drawings
Fig. 1 is the figure of the heat-treat condition in the manufacture method of wire rod of explanation an embodiment of the invention.
Fig. 2 is the tensile strength TS (N/mm representing in the wire rod of an embodiment of the invention2) and C content (matterAmount %) the figure of an example of relation.
Fig. 3 is represent heat-treat condition in the manufacture method of wire rod of an embodiment of the invention and wire rod anti-The figure of the relation of tensile strength inequality.
Fig. 4 is the flow chart that represents the wire rod of an embodiment of the invention or the manufacture method of steel wire.
Fig. 5 is the flow chart that represents the manufacture method of the steel wire of another embodiment of the invention.
Fig. 6 is the figure that represents the method for the area occupation ratio of obtaining bainite.
Fig. 7 is the schematic diagram of wire rod shape when wire rod is immersed in molten salt bath or molten lead bath.
Detailed description of the invention
Below, embodiments of the present invention are described.
Wire drawing characteristic to present embodiment and the hypereutectoid bainite of delayed fracture resistance characteristics excellence wire rod for steel wire (withUnder be sometimes referred to as " wire rod of present embodiment ") describe.
The wire rod of present embodiment is characterised in that to have following compositions composition: % contains C in unit mass: exceed0.80～1.20％、Si：0.10～1.50％、Mn：0～1.00％、P：0～0.02％、S：0～0.02％、Cr：0～1.00％、Ni：0～1.00％、Cu：0～1.00％、Mo：0～0.50％、Ti：0～0.20％、Nb：0～0.20％、V：0～0.20%, B:0～0.0050%, Al:0～0.10% and Ca:0～0.05%, remainder comprise Fe and impurity, are passing through generalLength is the situation that the test film that 8 length are 400mm is manufactured in unit that the wire rod of 3200mm is divided into 8 equal lengthUnder, the average tensile strength TS of each above-mentioned test film is with the N/mm of unit2Meter meets following formula 1, each above-mentioned test film each above-mentionedMaximum in tensile strength and the difference of minimum of a value are 50N/mm2Below, the average drawing value RA of each above-mentioned test film is with listPosition % meter meets following formula 2.
[TS]≤810 × [C]+475 (formula 1)
[RA] >=-0.083 × [TS]+154 (formula 2)
Wherein, [C] is the C content of the above-mentioned wire rod in unit mass %, and [TS] is with the N/mm of unit2The above-mentioned of meter put downAll tensile strength TS.
First, the one-tenth of the wire rod to present embodiment is grouped into and describes. Below, unit " % " refers to " quality % ".
C: exceed 0.80～1.20%
C improves the hardenability of wire rod and the element of tensile strength. By improving the hardenability of wire rod, main group of wire rodKnit and become bainite. When C content exceedes 0.80%, can obtain needed hardenability and tensile strength. On the other hand, C contentWhile exceeding 1.20%, generate and just analyse cementite, in the time of the Wire Drawing of wire rod, become easy generation broken string. Therefore, in order to suppressJust analyse the generation of cementite, the higher limit of C content is set as to 1.20%. For bainite is generated further easily, also canSo that the lower limit of C content is set as to 0.85%, 0.90% or 0.95%. In addition,, because tensile strength is when too high, wire rod is to prolongingThe sensitiveness of fracture improves late, so also the lower limit of C content can be set as to 1.15%, 1.10% or 1.05%.
Si：0.10～1.50％
Si is the element that improves the tensile strength of wire rod. In addition, Si is the element as deoxidier performance function. Due to SiContent lower than 0.10% time, can not get above-mentioned effect, so the lower limit of Si content is set as to 0.10%. But, in mistakeIn eutectoid steel, Si promotes just to analyse ferritic separating out. Just analyse ferrite and have the possibility that produces broken string in the time of the Wire Drawing of wire rodProperty. And then Si is in hypereutectoid steel, makes in addition the possibility of the limit degree of finish reduction in Wire Drawing. Therefore, by Si contentHigher limit be set as 1.50%. In order further to improve the above-mentioned effect of being brought by Si, also can be by the lower limit of Si contentValue is set as 0.15%, 0.20% or 0.25%. In addition, for Wire Drawing is more prone to, also can be by Si content upperLimit value is set as 1.45%, 1.40% or 1.35%.
Mn：0～1.00％
The wire rod of present embodiment does not need to contain Mn. Therefore, the lower limit of the Mn content of the wire rod of present embodiment is0%. But Mn has the effect that improves the intensity of wire rod by the hardenability of raising wire rod. In addition, Mn be with Si similarlyFor the element working as deoxidier. Therefore, also can in wire rod, contain as required Mn. Mn content exceedes 1.00%Time, in the segregation portion of Mn, hardenability improves, and the time till finishing to phase transformation is elongated. ,, in this situation, in wire rod, quenchIt is different that bad temper becomes, and the position high in hardenability produces martensite, and this martensite becomes the reason of broken string in the time of Wire Drawing.Therefore, the higher limit of Mn content need to be set as to 1.00%. In addition, in order further to improve wire drawing characteristic, also can be by MnThe higher limit of content is set as 0.90% or 0.80%. The lower limit of Mn content is 0%, but in order to obtain above-mentioned effect, MnThe lower limit of content is preferably 0.20%, and more preferably 0.40%.
P：0～0.02％
S：0～0.02％
P and S are impurity elements. When P and S exist in large quantities in wire rod, the ductility of wire rod reduces. Therefore, P and SHigher limit is 0.02%. The higher limit of P content and S content is all preferably 0.01%, is more all preferably 0.005%. Because P containsAmount and S content are more few more preferred, so the lower limit of P content and S content is 0%. But, the content of these elements is reduced toBelow 0.001%, can cause the rising of the manufacturing cost of wire rod. Therefore, in practical steel, the lower limit of P content and S content reaches conventionallyTo 0.001%.
The wire rod of present embodiment, except above-mentioned element, is not hindering the scope of characteristic of wire rod of present embodimentInside also can suitably contain Cr, Ni, Cu, Mo, Ti, Nb, V, B, Al and Ca. But, because containing of these elements is not necessary, so the lower limit of the content of these elements is 0%.
Cr：0～1.00％
Cr is the element that improves the hardenability of wire rod and promote thus bainitic transformation. When Cr content exceedes 1.00%, fromPhase transformation start till phase transformation to finish the needed time elongated, become to the heat treatment time completing till bainitic transformation thusLong, so not preferred. In addition, identical with Mn, exceeding 1.00% Cr also has and in wire rod, generates martensitic possibility. CauseThis, be set as 1.00% by the higher limit of Cr content. Cr content is preferably below 0.50%, more preferably below 0.30%. CrThe lower limit of content is 0%, but in order to obtain above-mentioned effect, also can contain more than 0.01%, more preferably more than 0.05%Cr.
Ni：0～1.00％
Ni and Cr are similarly the elements that improves the hardenability of wire rod and advance thus bainitic transformation. Ni content exceedes1.00% time, the ductility of ferritic phase reduces. Therefore, the higher limit of Ni content is set as to 1.00%. Ni content is preferablyBelow 0.70%, more preferably below 0.50%. The lower limit of Ni content is 0%, but in order to obtain above-mentioned effect, also canContain preferably more than 0.05%, more preferably more than 0.10% Ni.
Cu：0～1.00％
Cu is the element that improves the corrosion fatigue characteristic of wire rod. When Cu content exceedes 1.00%, the ferrite in bainiteDuctility reduce. Therefore, the upper limit of Cu content is set as to 1.00%. Cu content is preferably below 0.70%, more preferablyBelow 0.50%. The lower limit of Cu content is 0%, but in order to obtain above-mentioned effect, also can contain preferably more than 0.05%,More preferably more than 0.10% Cu.
Mo：0～0.50％
Mo is the element that improves the hardenability of wire rod. When Mo content exceedes 0.50%, the hardenability of wire rod excessively improves,Have thus and in Mo segregation portion, separate out micro-martensitic possibility. The situation that micro-martensite has the ductility that makes wire rod to reduce. CauseThis, be set as 0.50% by the higher limit of Mo content. Mo content is preferably below 0.30%, more preferably below 0.10%. MoThe lower limit of content is 0%, but in order to obtain above-mentioned effect, also can contain preferably more than 0.01%, more preferably 0.03%Above Mo.
Ti：0～0.20％
Nb：0～0.20％
V：0～0.20％
Ti, Nb and V are by the γ particle diameter miniaturization of heated wire rod. In this situation, due to institute's shape in the time that wire rod is cooledThe tissue becoming is micronized, so the toughness of wire rod improves. On the other hand, when the content of Ti, Nb and V exceedes 0.20%, to thisThe characteristic of the wire rod of embodiment causes harmful effect. Therefore, the higher limit of the content of Ti, Nb and V is all set as 0.20%.The content of Ti, Nb and V is all preferably below 0.15%, more preferably below 0.10%. The lower limit of the content of Ti, Nb and V is equalBe 0%, but in order to obtain above-mentioned effect, also the lower limit of the content of Ti, Nb and V can be preferably set to separately0.01%, be more preferably set as 0.02%.
B：0～0.0050％
B can improve the hardenability of wire rod. When B content exceedes 0.0050%, the hardenability of wire rod becomes too high, so have logicalCross the possibility that forms martensite and cause the ductility of wire rod to reduce in wire rod. Therefore, the higher limit of B content is set as0.0050%. B content is preferably below 0.0040%, more preferably below 0.0030%. The lower limit of B content is 0%, but isObtain above-mentioned effect, also can contain preferably more than 0.0005%, more preferably more than 0.0010% B.
Al：0～0.10％
Al is the element as deoxidier performance function. When Al content exceedes 0.10%, generate the alumina series folder of hardForeign material, this field trash can make the ductility of wire rod and stringiness reduce. Therefore, the higher limit of Al content is set as to 0.10%.Al content is preferably below 0.07%, more preferably below 0.05%. The lower limit of Al content is 0%, but above-mentioned in order to obtainEffect, also can contain preferably more than 0.01%, more preferably more than 0.02% Al.
Ca：0～0.05％
Ca is the form of MnS by the field trash of controlling in wire rod, and the delayed fracture resistance characteristics of wire rod is improved. But,When Ca content exceedes 0.05%, Ca generates thick field trash, and the delayed fracture resistance characteristics of wire rod reduces thus. Therefore, by CaThe higher limit of content is set as 0.05%. Ca content is preferably below 0.04%, more preferably below 0.03%. Under Ca contentLimit value is 0%, but in order to obtain above-mentioned effect, also can contain preferably more than 0.001%, more preferably more than 0.005%Ca。
The remainder that the one-tenth of the wire rod of present embodiment is grouped into comprises Fe and impurity. Impurity refers in industrial manufactureWhen steel, the composition of sneaking into by the various principal elements of such raw material such as ore or waste material or manufacturing process, is notCan cause the composition allowing in dysgenic scope to the wire rod of present embodiment.
Then, the metal structure of the wire rod to present embodiment describes.
Bainite: 90～100 area %
The bainite that the metal structure of the wire rod of present embodiment contains 90～100 area %. Metal structure contains 90～The wire drawing characteristic of the wire rod (bainite wire rod) of the bainite of 100 area % is than the main wire rod being made up of pearlite of metal structure(pearlitic wires) excellence. In addition, because the cementite comprising in bainite is finer than the cementite comprising in pearlite, soWhen one-tenth is grouped into identical bainite wire rod and pearlitic wires comparison, the tensile strength of bainite wire rod compares pearlitic wiresTensile strength low. When the tensile strength of wire rod is low, wire rod and this wire rod is carried out to Wire Drawing and the extension of the steel wire that obtainsProperty, wire drawing characteristic and processability are high. For these characteristics are further improved, the lower limit of bainite content can be setBe 95 area %, also can be set as 98 area %. Except bainite, such as micro-martensite (MA), just analyse cementite etc.There is the situation in the metal structure that is included in wire rod. As long as the content of bainite is that containing of they permitted 90 area % abovePermitted.
The content of bainite is obtained by observing the wire rod cross section vertical with wire-drawing direction. For measuring containing of bainiteThe example of the method for amount is as described below. First, in multiple positions in the wire rod cross section vertical with wire-drawing direction, obtain metal groupKnit image. Then, obtain the mean value of the area occupation ratio of the bainite in each metal structure image. Obtain the bat of metal structure imageTaking the photograph region is not particularly limited. For example as shown in Figure 6, the preferred central part in the wire rod cross section 1 vertical with wire-drawing direction11, the region of 1/4 of skin section 12 and gauge or diameter of wire the degree of depth is that pars intermedia 13 comprises respectively each other 4 of isolation as much as possibleShooting area 2. Be not particularly limited for the means that obtain metal structure image. For example, (scanning electron is aobvious preferably to use SEMMicro mirror), to take multiplying power as 1000 times of shooting metal structure images. The means of differentiating bainite in metal structure image do not haveBe particularly limited. In view of its one-tenth is grouped into, the wire rod that can be considered as present embodiment does not comprise and (comprises micro-except pearlite, martensiteMartensite), just analyse the tissue beyond cementite and bainite, so in the metal structure image of the wire rod of present embodiment,Also can will be considered as bainite except pearlite, martensite and the tissue of just analysing cementite.
Then, the mechanical property of the wire rod to present embodiment describes.
Average tensile strength TS:810 × [the C]+475N/mm of wire rod2Below
The mechanical property of the wire rod of present embodiment can be evaluated by the characteristic of measuring following test film: by growingDegree has 8 test films that length is 400mm that 8 unit of equal length obtain for the wire rod of 3200mm is divided into. OnThe mean value of the tensile strength of 8 test films stating is defined as the average tensile strength TS of wire rod. The wire rod of present embodimentAverage tensile strength TS meet following formula 1.
[TS]≤810×[C]+475(1)
Wherein, [C] is the C content of the wire rod in unit mass %, and [TS] is with the N/mm of unit2The average tensile of meter is strongDegree TS.
The main cause that the tensile strength of wire rod is increased is the C content of wire rod and the wire rod heat-treat condition while manufacturing.The increase of tensile strength of C content of wire rod of resulting from can not make the tensile strength inequality of wire rod. Its reason is, follows C to containThe increase of amount and the increase of the tensile strength that produces spreads all over wire rod entirety and equally produces. On the other hand, result from wire rod systemThe increase of the tensile strength of the heat-treat condition while making has the possibility of the tensile strength inequality that makes wire rod. Particularly wire rod is straightIn the little situation in footpath, the thermal capacity of the per unit length of wire rod is little, and it is large that the Temperature Distribution of the length direction of wire rod becomes, so onlineIn material entirety, equally heat-treat and become difficult, easily produce the inequality of tensile strength. The shadow that heat treatment causes tensile strengthSound is larger, and the inequality of tensile strength also becomes larger. When the tensile strength of wire rod is uneven, the processability of wire rod and steel wire is notAll, so the machining of wire rod and steel wire becomes difficulty. And then, in this situation, in the high position of the tensile strength of wire rod, to prolongingThe sensitiveness of fracture (hydrogen embrittlement) improves late, and generation is lost.
In view of above item, the average tensile strength of the wire rod of present embodiment need to be lower than only specifying by C contentHigher limit. People of the present invention define the higher limit of average tensile strength TS by above-mentioned formula 1.
Coefficient " 810 " in above-mentioned formula 1 and " 475 " are for exceeding 0.80% wire rod at C content, C content exceedes eutectoidIn the wire rod of point, the coefficient that people of the present invention obtain by experiment. People of the present invention recognize: the average tensile strength TS of wire rodWhile being greater than through type 1 set upper limit value when too high with respect to C content, average tensile strength (), heat treatment is to tensile strengthThe impact causing is increased to unsuitable level, so the inequality of the tensile strength of wire rod becomes greatly, machining is stable thusProperty suffers damage, and becomes easy generation and lose. In this situation, think: the heat-treat condition when manufacture of wire rod is inappropriate, because ofThe tensile strength of this wire rod improves unevenly.
The TS of average tensile strength shown in Fig. 2 (N/mm2) with an example of the relation of C content (quality %). Can by figureKnow, the average tensile strength TS of the wire rod of present embodiment is in the region of " [TS]≤810 × [C]+475 ".
The lower limit of the tensile strength of wire rod does not have special provision. But, conventionally the wire rod of industrial utilization is required to oneDetermine the tensile strength of degree. When the average tensile strength of wire rod is too low with respect to C content, also become difficult at the industrial wire rod that utilizes.Therefore, also can be by following formula 1 ', formula 1 " or formula 1 " ' carry out the average tensile strength of the wire rod of regulation present embodiment.
810 × [C]+425≤[TS]≤810 × [C]+475 (formula 1 ')
810 × [C]+435≤[TS]≤810 × [C]+475 (formula 1 ")
810 × [C]+445≤[TS]≤810 × [C]+475 (formula 1 " ')
More than the average drawing value RA:-0.083 × TS+154 of wire rod
The evaluation of the mechanical property of the wire rod of present embodiment is undertaken by the characteristic of measuring following test film: by inciting somebody to actionLength is that the wire rod of 3200mm is divided into and has 8 test films that length is 400mm that 8 unit of equal length obtain.The mean value of the drawing value of 8 above-mentioned test films is defined as the average drawing value RA of wire rod. The wire rod of present embodimentAverage drawing value RA meets following formula 2.
[RA] >=-0.083 × [TS]+154 (formula 2)
Wherein, [TS] is with the N/mm of unit2The average tensile strength TS of meter.
In addition, in the wire rod of present embodiment, limit on average by the lower limit being calculated by average tensile strength TS,The lower limit of drawing value RA.
Coefficient " 0.083 " and " 154 " in above-mentioned formula 2 are: people of the present invention by inquiry C content in hypereutectoid districtThe average tensile strength of the various wire rods in territory and average drawing value, the coefficient of obtaining according to experiment. Described later by this enforcementThe drawing value of the wire rod that the manufacture method of mode obtains at least has " 0.083 × [TS]+154 " above average drawing value. ShouldAverage drawing value is the value that exceedes the average drawing value of pearlitic wires in the past. On the other hand, metal structure do not have 90～The average drawing value of the wire rod of 100% bainite is lower than above-mentioned lower limit. In addition, metal structure is mainly by bainite structureBecome but flat by wire rod that the austenite of supercooling state is heated to obtain before the beginning of bainitic transformation of this bainiteAll drawing value is also low than above-mentioned lower limit.
The uneven amplitude of the tensile strength of wire rod: the maximum in each tensile strength of 8 test films and minimum of a value poorFor 50N/mm2Below
The evaluation of the mechanical property of the wire rod of present embodiment is undertaken by the characteristic of measuring following test film: by inciting somebody to actionLength is that the wire rod of 3200mm is divided into and has 8 test films that length is 400mm that 8 unit of equal length obtain.In the wire rod of present embodiment, the maximum in each tensile strength of above-mentioned each test film and the difference of minimum of a value are defined asThe uneven amplitude of the tensile strength of wire rod. The uneven amplitude of the tensile strength of the wire rod of present embodiment is 50N/mm2Below.
When the tensile strength of wire rod is large, wire rod and wire rod is carried out to Wire Drawing and the processability of the steel wire that obtains diminishes.The uneven amplitude of the tensile strength of wire rod exceedes 50N/mm2Time, obtain by this wire rod and by this wire rod is carried out to Wire DrawingTo steel wire process under certain condition become difficulty. And then, in this situation, in the high position of the tensile strength of wire rodThe sensitiveness of delayed fracture (hydrogen embrittlement) is improved, and generation is lost. For the processing of wire rod and steel wire being more prone to and furtherSuppress the generation of losing of wire rod, the uneven amplitude of the tensile strength of wire rod can be also 45N/mm240N/mm below,2Below,35N/mm2Below or 30N/mm2Below.
The diameter of the wire rod of present embodiment does not have special provision. But, in order further to suppress the tensile strength of wire rodInequality, also the diameter of wire rod can be set as to 3.5～16.0mm. As described above, the diameter of wire rod is during lower than 3.5mm,The thermal capacity of the per unit length of wire rod is little, and it is large that the Temperature Distribution of the length direction of wire rod becomes, so the same in wire rod entiretyHeat-treat and become difficult, easily produce the inequality of tensile strength. On the other hand, when the diameter of wire rod exceedes 16.0mm, under havingState possibility: be difficult to, by the same with skin section the central part of wire rod cooling, be difficult to the metal structure system of the central part of wire rodBecome the metal structure of regulation.
Then, the manufacture method of the wire rod to present embodiment and steel wire (is sometimes referred to as " manufacture of present embodiment belowMethod ") describe.
The manufacture method of the wire rod of present embodiment as shown in Figure 4, possesses following operation: (a) will have above-mentionedThe billet rolling that is grouped into of the one-tenth of wire rod of present embodiment and obtain the operation of wire rod; (b) by the wire rod of 850～1050 DEG CBe immersed in the 1st molten salt bath or molten lead bath of 350～450 DEG C, then by wire rod from the 1st molten salt bath or molten lead bathThe operation of taking out; (c) t of the beginning of the bainitic transformation of the moment in 5 seconds from taking out and wire rodsBefore second～tsAfter secondMoment, wire rod is immersed in to the operation in the 2nd molten salt bath or the molten lead bath of 530～600 DEG C; (d) by above-mentioned wire rodThe operation of taking out from the 2nd molten salt bath or molten lead bath after above-mentioned bainitic transformation finishes completely. tsBy following formula 3Obtain.
ts＝0.05×tComplete(formula 3)
tCompleteBe illustrated in by wire rod in the 1st molten salt bath or molten lead bath, continue dipping in the situation that, in unit secondStart till the time finishing from the bainitic transformation of wire rod. The manufacture method of the hypereutectoid bainite steel wire of present embodimentAs shown in Figure 4, except above-mentioned (a)～(d), also possess and wire rod is being immersed in to the 1st molten salt bath or fusion of leadBefore in bath, wire rod is carried out Wire Drawing and obtains the operation of steel wire. In addition the hypereutectoid of another embodiment of the invention,The manufacture method of bainite steel wire as shown in Figure 5, except above-mentioned (a)～(d), also possesses (e) to from the 2nd meltingThe wire rod taking out in salt bath or molten lead bath is implemented the operation of Wire Drawing. In addition, in Fig. 4 and Fig. 5, " molten salt bath or moltenMelt lead bath " note by abridging as " bath ". Below, there is following possibility: will be " at the t of the beginning of the bainitic transformation of wire rodsBefore second～tsSecondAfter moment wire rod is immersed in the 2nd molten salt bath or molten lead bath " be recited as " large with the beginning of the bainitic transformation of wire rodCause and side by side wire rod is immersed in the 2nd molten salt bath or molten lead bath ".
The heat treatment of the manufacture method of present embodiment shown in Fig. 1. The arrow of the symbol with (b) in figure represent byThe wire rod of 850～1050 DEG C is in the temperature T of the scope of 350～450 DEG C1The 1st molten salt bath or molten lead bath in flood, thenTake out i.e. above-mentioned (b). In (b), wire rod is in temperature T1Under be kept, take out, be then transferred to the 2nd molten salt bath or moltenMelt in lead bath. T in figure1Represent that the time that wire rod is flooded in the 1st molten salt bath or molten lead bath is with molten from the 1st by wire rodMelting salt bath or molten lead bath is transferred to the total of the time in the 2nd molten salt bath or molten lead bath and (, is submerged in from wire rodIn 1 molten salt bath or molten lead bath time be carved into wire rod and be submerged in till the moment in the 2nd molten salt bath or molten lead bathTime). The arrow of the symbol with (c) in figure represents roughly side by side wire rod to be immersed in the beginning of bainitic transformationTemperature (the T of the scope of 530～600 DEG C1+ Δ T) the 2nd molten salt bath or molten lead bath in, i.e. above-mentioned (c). Band in figureThere is the arrow of the symbol of (d) to be illustrated in, in the 2nd molten salt bath or molten lead bath, wire rod is retained to bainitic transformation and finish completelyTill, i.e. above-mentioned (d).
The temperature of the wire rod before being immersed in the 1st molten salt bath or molten lead bath: 850～1050 DEG C
In the manufacture method of the wire rod of present embodiment, first, the one-tenth of wire rod with present embodiment is grouped intoBillet rolling and obtain wire rod. Then, this wire rod is immersed in the 1st molten salt bath or molten lead bath. Can and soak in rollingTemporarily that wire rod is cooling between stain, then heat again, yet can between rolling and dipping, not carry out cooling and heat again. ThisAlso can between rolling and dipping, carry out Wire Drawing to wire rod outward. In either case, be immersed in the 1st molten salt bath orThe temperature of the wire rod in molten lead bath is all set as 850～1050 DEG C. Conventionally, because the temperature of the wire rod after just rolling is 1050Below DEG C, thus by the steel wire direct impregnation after the wire rod after rolling or wire drawing in the 1st molten salt bath or molten lead bath (,Do not carry out cooling and flood heatedly again) time, the upper limit of the wire rod flooding or the temperature of steel wire reaches in fact 1050 DEG C. ThisOutward, even by the steel wire after the wire rod after rolling or wire drawing temporarily cooling, then after heating, be immersed in the 1st molten salt bath againOr in situation in molten lead bath, also can wire rod in the 1st molten salt bath or molten lead bath or the temperature of steel wire will be immersed inHigher limit be set as 1050 DEG C. This is because wire rod or steel wire heating to a 1050 DEG C above advantage are not existed. If dippingWire rod in the 1st molten salt bath or molten lead bath or the temperature of steel wire, lower than 850 DEG C, do not become wire rod or steel wire are filledPoint quench, be set as so be immersed in the lower limit of the temperature of wire rod in the 1st molten salt bath or molten lead bath or steel wire850 DEG C. In addition, while wire rod being carried out to Wire Drawing between rolling and dipping, by " wire rod " in the explanation of following operationRecord suitably change " steel wire " into.
The temperature of the 1st molten salt bath or molten lead bath: 350～450 DEG C
In the manufacture method of the wire rod of present embodiment, by the wire rod of 850～1050 DEG C being immersed in to the 1st molten salt bathOr in molten lead bath, carry out quenching (in Fig. 1 (b)). The temperature T of the 1st molten salt bath or molten lead bath1It is 350～450 DEG C. LogicalCross this quenching, the metal structure of wire rod becomes the austenite of supercooling state. If wire rod is carried out to isothermal maintenance with this state,The austenitic bainitic transformation of supercooling state starts.
The temperature T of the 1st molten salt bath or molten lead bath1While exceeding 450 DEG C, the cooling velocity of wire rod reduces, so wire rodMetal structure before the austenite that becomes supercooling state, carry out bainitic transformation. In this situation, the tensile strength of wire rod is fallenLow, just analyse cementite but separate out in wire rod. Just analyse cementite and can make the wire drawing characteristic degradation of wire rod. Therefore, for by wire rodQuenching, need to be by the temperature T of the 1st molten salt bath or molten lead bath1Be set as below 450 DEG C. On the other hand, the 1st molten salt bathOr the temperature T of molten lead bath1During lower than 350 DEG C, the possibility that has the 1st molten salt bath or molten lead bath to solidify. By wire rodThe time being immersed in the 1st molten salt bath or molten lead bath need to be according to carrying out wire rod to be immersed in the 2nd as specifiedThe mode of the operation in molten salt bath or molten lead bath is suitably adjusted.
Wire rod is immersed in to the moment in the 2nd molten salt bath or molten lead bath: for from by wire rod from the 1st molten salt bath or moltenMelt taking-up in lead bath and play 5 seconds taking the interior moment and as the t of the beginning of the bainitic transformation of wire rodsBefore second～tsSecond after timeCarve.
In the manufacture method of the wire rod of present embodiment, be T from temperature1The 1st molten salt bath or molten lead bath in getGo out wire rod and play 5 seconds taking the interior moment and as the t of the beginning of the bainitic transformation of wire rodsBefore second～tsMoment after second, by wire rodBeing immersed in temperature is T2The 2nd molten salt bath or molten lead bath in.
People of the present invention by make from wire rod be submerged in the 1st molten salt bath or molten lead bath time to be carved into wire rod immersedTime till the moment of stain in the 2nd molten salt bath or molten lead bath, (, wire rod was submerged in the 1st molten salt bath or meltingTime in lead bath and wire rod are transferred to the time the 2nd molten salt bath or molten lead bath from the 1st molten salt bath or molten lead bathTotal ascent time) t1Temperature T with the 1st molten salt bath or molten lead bath1What change variously creates conditions to manufacture wire rod,Measure the uneven amplitude of the tensile strength of these wire rods. Use the data that obtain thus, investigation temperature T1, time t1And tension is strongThe relation of the uneven amplitude of degree. Consequently, obtain the result shown in Fig. 3.
The curve with symbol " S " in Fig. 3 be the curve that represents the temperature and time that starts of bainitic transformation (hereinafter referred to asFor S curve). This curve is grouped into and changes according to the one-tenth of wire rod. The data point of recording in Fig. 3 represents to manufacture this data pointWire rod time temperature T1And time t1. Before the wire rod of the data point of the side that more keeps left than curve is the beginning at bainitic transformationBeing submerged in the wire rod in the 2nd molten salt bath or molten lead bath, is being at Bei Shi than the wire rod of curve data point more on the right sideAfter the beginning of body phase transformation, be submerged in the wire rod in the 2nd molten salt bath or molten lead bath. In Fig. 3, record about each data pointDotted line represent the thermal history of the wire rod of each data point. The kind of data point is the uneven width of the tensile strength of the wire rod of " BAD "Degree exceedes 50N/mm2, the uneven amplitude of the tensile strength of the wire rod that the kind of data point is " GOOD " is for exceeding 40N/mm2And50N/mm2The uneven amplitude of the tensile strength of the wire rod that below, the kind of data point is " VERYGOOD " is 40N/mm2Below.
As represented in Fig. 3, (, large with the beginning of bainitic transformation with the wire rod of the approaching data point of curveCause the wire rod being side by side submerged in the 2nd molten salt bath or molten lead bath) in, the uneven amplitude of tensile strength is little.
Time t1According to the t of the beginning of the bainitic transformation at wire rodsBefore second～tsMoment wire rod after second is submerged in theMode in 2 molten salt baths or molten lead bath is suitably set. tsRefer to the value of obtaining by formula shown below 3.
ts＝0.05×tComplete(formula 3)
tCompleteBe illustrated in by wire rod in the 1st molten salt bath or molten lead bath, continue dipping in the situation that, in unit secondStart till the time finishing from the bainitic transformation of wire rod.
From wire rod is immersed in to the 1st molten salt bath or molten lead bath till the time that the bainitic transformation of wire rod startsAnd ts, be that basis decides with the temperature that the one-tenth of wire rod is grouped into corresponding S curve and the 1st molten salt bath or molten lead bath.Therefore, be grouped into and simulation and/or the preliminary experiment of the temperature of the 1st molten salt bath or molten lead bath by the one-tenth based on wire rod, askGo out time t1. In addition as described later, by detecting the backheat of wire rod, obtain from wire rod being immersed in to the 1st molten salt bath or molten,Melt in lead bath till the time that the bainitic transformation of wire rod starts. Therefore, also can be before manufacture wire rod, by above-mentioned handSection, carries out for determining time t1The investigation of preparation.
By roughly side by side wire rod being immersed in to the 2nd molten salt bath or fusion of lead with the beginning of the bainitic transformation of wire rodIn bath, the reason that the inequality of the tensile strength of wire rod is inhibited is also unclear. But, be estimated as the reason of following explanation. LineDuring the bainitic transformation of material floods in the 1st molten salt bath or molten lead bath or to the 2nd molten salt bath or molten lead bathWhile generation in transfer, by backheat (phase transformation heating), during flooding in the 1st molten salt bath or molten lead bath or to the 2nd, meltMelt in the transfer of salt bath or molten lead bath, wire temperature rises. In this situation, there is the rising that produces unevenly wire temperaturePossibility. Its reason is, carry out the heat treatment of wire rod in molten salt bath or molten lead bath time, wire rod is for example to have as figureShown in 7, the state of such web-shaped is submerged in molten salt bath or molten lead bath, is then removed. Line in heat treatmentWhen material has web-shaped, the part that wire rod overlaps each other, compared with part in addition, results from the temperature rise of backheatBecome large. Its reason is to be, in the part that the cooling effect being brought by the 1st molten salt bath or molten lead bath overlaps each other at wire rodRelatively be difficult to reach. Therefore, by above-mentioned time t1In the slack-off situation of the beginning of the heating of elongated and wire rod, wire temperatureInhomogeneous rising, thereby produce the inequality of tensile strength of wire rod. In addition, in the time of heat treatment, wire rod is made to web-shapedManufacture efficiency in order to improve wire rod and indispensable. As long as no special reason, can be not there is wire rod each otherThe state of the shape not overlapping is immersed in wire rod in molten salt bath or molten lead bath. On the other hand, at above-mentioned time t1BecomeShort and exceeding t compared with the starting of bainitic transformationsBefore second, wire rod is submerged in the 2nd molten salt bath or molten lead bathTime, the starting in advance of phase transformation, so starting temperature of transformation uprises. In this situation, the rising of the intensity of generation wire rod and wire rodThe reduction of ductility.
In view of above-mentioned reason, the dipping of wire rod in the 2nd molten salt bath or molten lead bath most preferably with the Bei Shi of wire rodThe beginning of body phase transformation is carried out completely simultaneously. But, people of the present invention by the fact cognition of testing to: the carrying out of bainitic transformationIn the larger wire rod of the temperature rise of hurry up and caused by backheat, if between the beginning of the phase transformation of the dipping of wire rod and wire rod timeBetween be 5 seconds with the next inequality that can suppress fully the tensile strength of wire rod, the carrying out of this external bainitic transformation slow and byIn the lower wire rod of temperature rise that backheat causes, though the time between the beginning of the phase transformation of the dipping of wire rod and wire rod exceedWithin 5 seconds, also can suppress uneven. Based on such opinion, in the manufacture method of the wire rod of present embodiment, by according to Bei ShiThe carrying out speed of body phase transformation and the value t that determinessCarry out the time between the dipping of regulation wire rod and the beginning of the phase transformation of wire rod. SeparatelyOutward, in the wire rod of present embodiment, due to tCompleteCan not become lower than 100 seconds, so also can be by tsHigher limit be set as5 seconds.
In situation, moment and wire rod that wire rod is submerged in the 1st molten salt bath or molten lead bath are submerged in the 2nd mostlyElapsed time t between moment in molten salt bath or molten lead bath1Be preferably 10～40 seconds. In view of the wire rod of present embodimentOne-tenth be grouped into, by time t1Be set as, lower than 10 seconds or while exceeding 40 seconds, being difficult to suitably carry out ensuing wire rod the 2ndDipping in molten salt bath or molten lead bath.
Except above-mentioned regulation, wire rod also need to be in 5 seconds from taking out the 1st molten salt bath or molten lead bathBe submerged in the 2nd molten salt bath or molten lead bath. From wire rod be fetched into till dipping between time, the i.e. transfer of wire rodTime while exceeding 5 seconds, have the possibility of the temperature change of wire rod during the transfer of wire rod, thus with the Bei Shi of wire rodThe beginning of body phase transformation is roughly side by side immersed in wire rod in the 2nd molten salt bath or molten lead bath and becomes extremely difficult.
In wire rod in the 1st molten salt bath or molten lead bath, also can be by detecting the backheat (phase transformation heating) of wire rodJudge the moment that bainitic transformation starts. Backheat in present embodiment refers to, by opening of the bainitic transformation in wire rodThe at first phenomenon of the temperature rise of wire rod. Backheat can be got after for example flooding in the 1st molten salt bath or molten lead bathThe temperature of the temperature of the wire rod going out and the 1st molten salt bath or molten lead bath compares to detect. The temperature of wire rod is molten higher than the 1stWhile melting the temperature of salt bath or molten lead bath, judge and in wire rod, produce backheat. Making soaking in the 1st molten salt bath or molten lead bathThe stain time occurs in the wire rod of various variations, having or not of backheat by inquiry respectively, obtains and can make to produce back in wire rodThe shortest dip time t of heatmin. Can after being flooded in the 1st molten salt bath or molten lead bath, wire rod only pass through tmin'sMoment is considered as the moment that in wire rod, bainitic transformation starts. Further preferably: utilize like this backheat to obtain in advance in wire rodIn the moment that bainitic transformation starts, carry out the manufacture of wire rod based on this.
In addition, the time in the 1st molten salt bath or molten lead bath of being submerged in is during lower than 5 seconds, even if the temperature of wire rod is highIn the 1st molten salt bath or molten lead bath, also cannot judge whether to produce backheat in wire rod. This is because the temperature of wire rod hasNot to result from backheat but result from inadequate dip time and situation about uprising.
The temperature of the 2nd molten salt bath or molten lead bath: 530～600 DEG C
When wire rod taking-up from the 2nd molten salt bath or molten lead bath: the moment after bainitic transformation finishes completely
With the beginning of the bainitic transformation of wire rod roughly simultaneously, be T in temperature2The 2nd molten salt bath or molten lead bath inDipping wire rod. Temperature T2It is 530～600 DEG C. Thus, wire rod is heated to hastily till the temperature of 530～600 DEG C (in Fig. 1(c)), till can being retained to bainitic transformation and finishing completely with this temperature. If with the beginning of the bainitic transformation of wire rod roughlySide by side wire rod is heated to hastily to the temperature of 530～600 DEG C, the interval of the cementite in bainite broadens. Its resultBe, compared with not carrying out the situation of instant heating, the strength decreased of wire rod. The temperature of the 2nd molten salt bath or molten lead bath is lowIn 530 DEG C or while exceeding 600 DEG C, till the end of bainitic transformation, need cost long-time. Therefore, in order to make Bainite Phases of SomeChange completed reliably with the short time, and the Temperature Setting of the 2nd molten salt bath or molten lead bath is 530～600 DEG C. Wire rod is heated toFiring rate when above-mentioned temperature range is not particularly limited. But, for till foreshortening to bainitic transformation and completing timeBetween, the preferably very fast person of firing rate, particularly, is preferably 10～50 DEG C/sec. By in temperature being the melting of 530～600 DEG CIn salt bath or molten lead bath, flood wire rod, can obtain such firing rate. Before bainitic transformation completes, wire rod is molten from the 2ndMelt while taking-up in salt bath or molten lead bath, have following possibility: in wire rod, generate MA, this MA can make the processability of wire rod fallLow.
After in dipping at wire rod in the 1st molten salt bath or molten lead bath, bainitic transformation starts, if wire rod is keptAt this state, fine and close bainite structure growth. The wire rod of fine and close bainite structure growth and the beginning of bainitic transformationRoughly side by side the wire rod phase specific strength of instant heating is high. Therefore, with regard to the wire rod of present embodiment, by wire rod is carried outInstant heating, thus the interval expansion of the cementite of separating out is made to strength decreased.
The hypereutectoid bainite steel wire of the delayed fracture resistance characteristics excellence of present embodiment (is sometimes referred to as " this enforcement belowThe steel wire of mode ") for the wire rod of the present embodiment of wire drawing excellent is carried out to the steel wire that Wire Drawing obtains. Wire drawing addsWork is common Wire Drawing, and the contraction percentage of area is not particularly limited. The steel wire of present embodiment is due to delayed fracture resistanceExcellent, so the purposes of steel wire expands significantly.
Embodiment
Then, embodiments of the invention are described, but condition in embodiment be for confirm of the present invention can be realThe property executed and effect and a condition example adopting, the present invention is not limited to this condition example. The present invention only otherwise de-From purport of the present invention, the object of attainable cost invention, can adopt various conditions.
(embodiment 1)
The hypereutectoid steel billet that one-tenth shown in table 1 is grouped into is rolled into the wire rod of the wire diameter shown in table 2, shown in table 2Under temperature conditions, complete bainitic transformation. Measure the average tensile strength (N/mm of the wire rod after bainitic transformation completes2), averageUneven amplitude (the N/mm of drawing value (%) and tensile strength2). The average tensile strength of wire rod is for by being 3200mm by lengthWire rod be divided into test film that 8 length having 8 unit of equal length and obtain are 400mm tensile strength separatelyMean value. The average drawing value of wire rod is to be divided into 8 lists with equal length by the wire rod that is 3200mm by lengthThe mean value of the test film that 8 length first and that obtain are 400mm drawing value separately. The uneven amplitude of the tensile strength of wire rodWhat have 8 length that 8 unit of equal length obtain for being divided into by the wire rod that is 3200mm by length be 400mmMaximum in test film tensile strength separately and minimum of a value poor. Measurement result is shown in Table 2 in the lump. In addition, by lineFiring rate when material is immersed in the 2nd molten salt bath or molten lead bath is set as 10～50 DEG C/sec.
In table 2, T0For being submerged in the temperature of the wire rod in the 1st molten salt bath or molten lead bath, T1It is the 1st fuse saltThe temperature of bath or molten lead bath, t1For from flooding wire rod at the 2nd molten salt bath or molten in the 1st molten salt bath or molten lead bathMelt the time till dipping wire rod in lead bath, Δ T rises by flood wire rod in the 2nd molten salt bath or molten lead bathTemperature, T2Be the temperature of the 2nd molten salt bath or molten lead bath, the TS upper limit is the average tensile strength that calculated by C content and formula 1Higher limit, TS average out to average tensile strength (N/mm2), TS is the maximum (N/mm of tensile strength to the maximum2), TS is minimum for anti-Minimum of a value (the N/mm of tensile strength2), the uneven amplitude of TS is the poor (N/mm of TS maximum and TS minimum2), RA lower limit is by average tensileThe higher limit of the average drawing value that the higher limit of intensity and formula 2 calculate, the average drawing value of RA average out to (%), RA is drawing to the maximumThe maximum (%) of value, RA minimum is the minimum of a value (%) of drawing value, the uneven amplitude of RA is poor (%) of RA maximum and RA minimum.The dip time t of the wire rod in the 1st molten salt bath or molten lead bath while manufacturing the example of No.1～7 is the according to wire rodDipping in 2 molten salt baths or molten lead bath become with the beginning of bainitic transformation roughly mode simultaneously and suitably select timeBetween. In the comparative example of No.8, wire rod is not submerged in the 2nd molten salt bath or molten lead bath. In the comparison of No.9 and 10In example, wire rod is submerged in the 2nd molten salt bath or molten lead bath after the beginning of bainitic transformation after long-time. SeparatelyOutward, in example No.1～7, comparative example No.9 and comparative example No.10, wire rod is from the 1st molten salt bath or molten lead bathTake out and be submerged in the 2nd molten salt bath or molten lead bath with interior for 5 seconds.
As shown in Table 2, in the example of No.1～7, the average and RA of TS on average meets formula 1 and formula 2, in addition, and TS inequalityAmplitude is 50N/mm2Below. Hence one can see that, and in the example of No.1～7, delayed fracture resistance characteristics improves, at Wire bundlingTime and bundling state under do not lose.
Utilizability in industry
As mentioned above, according to the present invention, can provide the line that is in a ratio of low-intensity and high ductibility with pearlitic steelLosing when the bundling operation of material and wire rod or under the state of bundling is suppressed, wire drawing characteristic and delayed fracture resistance characteristics excellenceWire rod, use the hypereutectoid bainite steel wire of this wire rod manufacture and stably manufacture their manufacture method. Thereby, the present inventionIn steel industry, utilizability is high.
The explanation of symbol
1 wire rod cross section
11 central parts
12 skin section
13 pars intermedias
2 shooting areas

Claims (12)

1. a wire rod, is characterized in that, it has following compositions composition:
In unit mass, % contains:
C: exceed 0.80～1.20%,
Si：0.10～1.50％、
Mn：0～1.00％、
P：0～0.02％、
S：0～0.02％、
Cr：0～1.00％、
Ni：0～1.00％、
Cu：0～1.00％、
Mo：0～0.50％、
Ti：0～0.20％、
Nb：0～0.20％、
V：0～0.20％、
B：0～0.0050％、
Al:0～0.10% and
Ca：0～0.05％、
Remainder comprises Fe and impurity,
Wherein, the bainite that metal structure comprises 90～100 area %,
Manufacture in the unit that is divided into 8 equal length by the wire rod that is 3200mm by length the examination that 8 length are 400mmTest in the situation of sheet, the mean value TS of the tensile strength of each described test film is with the N/mm of unit2Meter meets following formula 1,
Maximum in the each described tensile strength of each described test film and the difference of minimum of a value are 50N/mm2Below,
The mean value RA of the drawing value of each described test film meets following formula 2 in the % of unit,
[TS]≤810 × [C]+475 formula 1
[RA] >=-0.083 × [TS]+154 formula 2
Wherein, [C] is the C content of the described wire rod in unit mass %, and [TS] is with the N/mm of unit2The described tension of meter is strongThe described mean value TS of degree, [RA] is the described mean value RA of the described drawing value in the % of unit.
2. a hypereutectoid bainite steel wire, is characterized in that, it is to add by wire rod claimed in claim 1 is carried out to wire drawingWork obtains.
3. a manufacture method for wire rod, is characterized in that, it is the manufacture method of wire rod claimed in claim 1, and it possessesFollowing operation:
Billet rolling is obtained to the operation of wire rod, described steel billet has following compositions composition:
In unit mass, % contains:
C: exceed 0.80～1.20%,
Si：0.10～1.50％、
Mn：0～1.00％、
P：0～0.02％、
S：0～0.02％、
Cr：0～1.00％、
Ni：0～1.00％、
Cu：0～1.00％、
Mo：0～0.50％、
Ti：0～0.20％、
Nb：0～0.20％、
V：0～0.20％、
B：0～0.0050％、
Al:0～0.10% and
Ca：0～0.05％、
Remainder comprises Fe and impurity;
The described wire rod of 850～1050 DEG C is immersed in the 1st molten salt bath or molten lead bath of 350～450 DEG C, then by instituteState the operation that wire rod takes out from described the 1st molten salt bath or molten lead bath;
The t of the beginning of the moment in 5 seconds from described taking-up and the bainitic transformation of described wire rodsBefore second～tsAfter secondIn the moment, described wire rod is immersed in to the operation in the 2nd molten salt bath or the molten lead bath of 530～600 DEG C; With
The work that described wire rod is taken out after described bainitic transformation finishes completely from described the 2nd molten salt bath or molten lead bathOrder,
ts＝0.05×tCompleteFormula 3
tCompleteBe illustrated in by described wire rod in described the 1st molten salt bath or molten lead bath, continue dipping in the situation that, with unit secondThe bainitic transformation from described wire rod of meter started till the time finishing.
4. the manufacture method of wire rod according to claim 3, is characterized in that, described wire rod is submerged in the described the 1st and meltsMelt moment in salt bath or molten lead bath and described wire rod be submerged in moment in described the 2nd molten salt bath or molten lead bath itBetween elapsed time be 10～40 seconds.
5. the manufacture method of wire rod according to claim 3, is characterized in that, sentences by the backheat that detects described wire rodThe described moment that described bainitic transformation in described wire rod in fixed described the 1st molten salt bath or molten lead bath starts.
6. a manufacture method for hypereutectoid bainite steel wire, is characterized in that, it is hypereutectoid Bei Shi claimed in claim 2The manufacture method of body steel wire, it possesses following operation:
Billet rolling is obtained to the operation of wire rod, described steel billet has following compositions composition:
In unit mass, % contains:
C: exceed 0.80～1.20%,
Si：0.10～1.50％、
Mn：0～1.00％、
P：0～0.02％、
S：0～0.02％、
Cr：0～1.00％、
Ni：0～1.00％、
Cu：0～1.00％、
Mo：0～0.50％、
Ti：0～0.20％、
Nb：0～0.20％、
V：0～0.20％、
B：0～0.0050％、
Al:0～0.10% and
Ca：0～0.05％、
Remainder comprises Fe and impurity;
The wire rod of 850～1050 DEG C is immersed in the 1st molten salt bath or molten lead bath of 350～450 DEG C, then by described lineThe operation that material takes out from described the 1st molten salt bath or molten lead bath;
The t of the beginning of the moment in 5 seconds from described taking-up and the bainitic transformation of described wire rodsBefore second～tsAfter secondIn the moment, described wire rod is immersed in to the operation in the 2nd molten salt bath or the molten lead bath of 530～600 DEG C;
The operation that described wire rod is taken out after described bainitic transformation finishes completely from the 2nd molten salt bath or molten lead bath;With
The described wire rod taking out is implemented to the operation of Wire Drawing from described the 2nd molten salt bath or molten lead bath,
ts＝0.05×tComplete
tCompleteBe illustrated in by described wire rod in described the 1st molten salt bath or molten lead bath, continue dipping in the situation that, with unit secondThe described bainitic transformation from described wire rod of meter started till the time finishing.
7. the manufacture method of hypereutectoid bainite steel wire according to claim 6, is characterized in that, described wire rod is impregnatedTime in described the 1st molten salt bath or molten lead bath is 10～40 seconds.
8. the manufacture method of hypereutectoid bainite steel wire according to claim 6, is characterized in that, by detecting described lineThe backheat of material is judged the institute that the described bainitic transformation in the described wire rod in described the 1st molten salt bath or molten lead bath startsState the moment.
9. a manufacture method for hypereutectoid bainite steel wire, is characterized in that, it is hypereutectoid Bei Shi claimed in claim 2The manufacture method of body steel wire, it possesses following operation:
The operation of the wire rod by billet rolling is obtained being carried out Wire Drawing and obtained steel wire, described steel billet has followingOne-tenth is grouped into:
In unit mass, % contains:
C: exceed 0.80～1.20%,
Si：0.10～1.50％、
Mn：0～1.00％、
P：0～0.02％、
S：0～0.02％、
Cr：0～1.00％、
Ni：0～1.00％、
Cu：0～1.00％、
Mo：0～0.50％、
Ti：0～0.20％、
Nb：0～0.20％、
V：0～0.20％、
B：0～0.0050％、
Al:0～0.10% and
Ca：0～0.05％、
Remainder comprises Fe and impurity;
The described steel wire of 850～1050 DEG C is immersed in the 1st molten salt bath or molten lead bath of 350～450 DEG C, then by instituteState the operation that steel wire takes out from described the 1st molten salt bath or molten lead bath;
The t of the beginning of the moment in 5 seconds from described taking-up and the bainitic transformation of described steel wiresBefore second～tsAfter secondIn the moment, described steel wire is immersed in to the operation in the 2nd molten salt bath or the molten lead bath of 530～600 DEG C; With
The work that described steel wire is taken out after described bainitic transformation finishes completely from described the 2nd molten salt bath or molten lead bathOrder,
ts＝0.05×tComplete
tCompleteBe illustrated in by described steel wire in described the 1st molten salt bath or molten lead bath, continue dipping in the situation that, with unit secondThe described bainitic transformation from described steel wire of meter started till the time finishing.
10. the manufacture method of hypereutectoid bainite steel wire according to claim 9, is characterized in that, described steel wire is immersedMoment and the described steel wire of stain in described the 1st molten salt bath or molten lead bath is submerged in described the 2nd molten salt bath or meltingElapsed time between moment in lead bath is 10～40 seconds.
The manufacture method of 11. hypereutectoid bainite steel wires according to claim 9, is characterized in that, described in detectingThe backheat of steel wire is judged what the described bainitic transformation in the described steel wire in described the 1st molten salt bath or molten lead bath startedThe described moment.
12. according to the manufacture method of the hypereutectoid bainite steel wire described in any one in claim 9～11, it is characterized in that,It possesses described steel wire to taking out from described the 2nd molten salt bath or molten lead bath further implements the operation of Wire Drawing.
CN201480055078.1A 2013-10-08 2014-10-08 Wire rod, hypereutectoid bainite steel wire and their manufacture method Expired - Fee Related CN105612269B (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP2013-211365 2013-10-08
JP2013211365 2013-10-08
PCT/JP2014/076938 WO2015053311A1 (en) 2013-10-08 2014-10-08 Wire rod, hypereutectoid bainite steel wire, and method for manufacturing same

Publications (2)

Publication Number Publication Date
CN105612269A true CN105612269A (en) 2016-05-25
CN105612269B CN105612269B (en) 2017-11-14

Family

ID=52813126

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201480055078.1A Expired - Fee Related CN105612269B (en) 2013-10-08 2014-10-08 Wire rod, hypereutectoid bainite steel wire and their manufacture method

Country Status (7)

Country Link
US (1) US20160244858A1 (en)
EP (1) EP3056580A4 (en)
JP (1) JP6079894B2 (en)
KR (1) KR101789949B1 (en)
CN (1) CN105612269B (en)
TW (1) TWI516611B (en)
WO (1) WO2015053311A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108138285A (en) * 2015-10-23 2018-06-08 新日铁住金株式会社 Wire Drawing steel wire material
CN109312436A (en) * 2016-07-05 2019-02-05 新日铁住金株式会社 Wire rod, steel wire and component

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6416709B2 (en) * 2015-07-21 2018-10-31 新日鐵住金株式会社 High strength PC steel wire
JP6416708B2 (en) * 2015-07-21 2018-10-31 新日鐵住金株式会社 High strength PC steel wire
CN105220786A (en) * 2015-10-17 2016-01-06 张磊 A kind of building heat preserving puigging
CN105178455A (en) * 2015-10-17 2015-12-23 张磊 Fireproof insulating layer of building exterior wall
KR102021199B1 (en) * 2017-11-27 2019-09-11 현대제철 주식회사 Steel and method of manufacturing the same
KR102362665B1 (en) * 2019-12-20 2022-02-11 주식회사 포스코 Wire rod, high strength steel wire and method for manufacturing thereof
JP7469643B2 (en) 2020-05-21 2024-04-17 日本製鉄株式会社 Steel wire, wire rods for non-tempered machine parts, and non-tempered machine parts

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH11293400A (en) * 1998-04-15 1999-10-26 Nippon Steel Corp High strength steel wire
JP2001220650A (en) * 1999-11-30 2001-08-14 Sumitomo Electric Ind Ltd Steel wire, spring and producing method therefor
JP2002241899A (en) * 2001-02-09 2002-08-28 Kobe Steel Ltd High strength steel wire having excellent delayed fracture resistance and excellent forging property and manufacturing method therefor
CN102301024A (en) * 2010-02-01 2011-12-28 新日本制铁株式会社 Wire material, steel wire, and processes for production of those products

Family Cites Families (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2742967B2 (en) * 1991-10-24 1998-04-22 新日本製鐵株式会社 Manufacturing method of bainite wire rod
JP2984886B2 (en) 1992-04-09 1999-11-29 新日本製鐵株式会社 Bainite wire or steel wire for wire drawing and method for producing the same
JP2984885B2 (en) 1992-04-09 1999-11-29 新日本製鐵株式会社 Bainite wire or steel wire for wire drawing and method for producing the same
JP2984887B2 (en) 1992-04-09 1999-11-29 新日本製鐵株式会社 Bainite wire or steel wire for wire drawing and method for producing the same
JP2984889B2 (en) 1992-07-08 1999-11-29 新日本製鐵株式会社 High carbon steel wire or steel wire excellent in wire drawability and method for producing the same
JP3400071B2 (en) * 1993-04-06 2003-04-28 新日本製鐵株式会社 High strength steel wire and high strength steel wire with excellent fatigue properties
US5662747A (en) * 1993-04-06 1997-09-02 Nippon Steel Corporation Bainite wire rod and wire for drawing and methods of producing the same
DE69424783T2 (en) * 1993-04-06 2000-11-23 Nippon Steel Corp., Tokio/Tokyo BAINITE ROD OR STEEL WIRE FOR DRAWING WIRE AND METHOD FOR THE PRODUCTION THEREOF
JP3018268B2 (en) * 1993-05-25 2000-03-13 新日本製鐵株式会社 High carbon steel wire or steel wire excellent in wire drawability and method for producing the same
US5658402A (en) * 1993-05-25 1997-08-19 Nippon Steel Corporation High-carbon steel wire rod and wire excellent in drawability and methods of producing the same
JP3388418B2 (en) 1994-06-21 2003-03-24 新日本製鐵株式会社 Method for producing high carbon steel wire or steel wire excellent in wire drawing workability
JPH083649A (en) * 1994-06-21 1996-01-09 Nippon Steel Corp Production of high carbon steel wire rod or steel wire excellent in wire drawability
JP3448459B2 (en) * 1997-06-10 2003-09-22 新日本製鐵株式会社 Wire rod for steel wire

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH11293400A (en) * 1998-04-15 1999-10-26 Nippon Steel Corp High strength steel wire
JP2001220650A (en) * 1999-11-30 2001-08-14 Sumitomo Electric Ind Ltd Steel wire, spring and producing method therefor
JP2002241899A (en) * 2001-02-09 2002-08-28 Kobe Steel Ltd High strength steel wire having excellent delayed fracture resistance and excellent forging property and manufacturing method therefor
CN102301024A (en) * 2010-02-01 2011-12-28 新日本制铁株式会社 Wire material, steel wire, and processes for production of those products

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108138285A (en) * 2015-10-23 2018-06-08 新日铁住金株式会社 Wire Drawing steel wire material
CN108138285B (en) * 2015-10-23 2020-02-21 日本制铁株式会社 Steel wire for wire drawing
CN109312436A (en) * 2016-07-05 2019-02-05 新日铁住金株式会社 Wire rod, steel wire and component
CN109312436B (en) * 2016-07-05 2021-08-10 日本制铁株式会社 Wire rod, steel wire and member

Also Published As

Publication number Publication date
TWI516611B (en) 2016-01-11
CN105612269B (en) 2017-11-14
KR101789949B1 (en) 2017-10-25
TW201516162A (en) 2015-05-01
EP3056580A1 (en) 2016-08-17
US20160244858A1 (en) 2016-08-25
EP3056580A4 (en) 2017-07-26
JP6079894B2 (en) 2017-02-15
WO2015053311A1 (en) 2015-04-16
JPWO2015053311A1 (en) 2017-03-09
KR20160048991A (en) 2016-05-04

Similar Documents

Publication Publication Date Title
CN105612269A (en) Wire rod, hypereutectoid bainite steel wire, and method for manufacturing same
JP7068434B2 (en) How to manufacture high-strength steel plate
CN107002198B (en) High strength cold rolled steel plate and its manufacturing method
CN102918174B (en) High-strength molten-zinc-plated steel sheet having excellent bendability and weldability, and process for production thereof
US20100319814A1 (en) Bainitic steels with boron
CN109790601A (en) Steel plate
EP2997168B1 (en) Method for producing a hot dip galvanized and or galvannealed steel sheet by quenching and partitioning
JP6047037B2 (en) Manufacturing method of high-strength cold-rolled steel sheet with excellent steel plate shape
JP3737354B2 (en) Wire rod for wire drawing excellent in twisting characteristics and method for producing the same
CN106133173A (en) The high strength cold rolled steel plate of uniform in material excellence and manufacture method thereof
BRPI0613975B1 (en) SEAMLESS STEEL TUBE AND ITS PRODUCTION METHOD
CN106687613A (en) High strength seamless steel pipe for use in oil wells and manufacturing method thereof
CN103842541A (en) High-strength galvannealed steel sheet of high bake hardenability, high-strength alloyed galvannealed steel sheet, and method for manufacturing same
JPWO2011089782A1 (en) Wire, steel wire, and method for manufacturing wire
JP5741456B2 (en) Alloyed hot-dip galvanized steel sheet and method for producing the same
WO2007007678A1 (en) Low-alloy steel for oil well tube having excellent sulfide stress cracking resistance
CN109280861A (en) Flat product and its production method with good resistance to ag(e)ing
CN106687614B (en) Oil well high-strength seamless steel pipe and its manufacturing method
CN104321454A (en) Steel wire for high-strength spring having exceptional coiling performance and hydrogen embrittlement resistance, and method for manufacturing same
CN106133176B (en) Pipe as fuel injection seamless steel pipe
WO2018020660A1 (en) High-strength steel sheet
KR102378147B1 (en) Hot rolled steel sheet and its manufacturing method
WO2015004902A1 (en) High-carbon hot-rolled steel sheet and production method for same
CN106133170A (en) High-carbon hot-rolled steel sheet and manufacture method thereof
CN106133169A (en) High-carbon hot-rolled steel sheet and manufacture method thereof

Legal Events

Date Code Title Description
C06 Publication
PB01 Publication
C10 Entry into substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant
CP01 Change in the name or title of a patent holder
CP01 Change in the name or title of a patent holder

Address after: Tokyo, Japan

Patentee after: NIPPON STEEL & SUMITOMO METAL Corp.

Address before: Tokyo, Japan

Patentee before: NIPPON STEEL & SUMITOMO METAL Corp.

CF01 Termination of patent right due to non-payment of annual fee
CF01 Termination of patent right due to non-payment of annual fee

Granted publication date: 20171114

Termination date: 20211008