EP3848477B1 - Kaltgewalztes stahlblech mit hohem kohlenstoffgehalt, verfahren zu seiner herstellung und maschinenteile aus stahl mit hohem kohlenstoffgehalt - Google Patents

Kaltgewalztes stahlblech mit hohem kohlenstoffgehalt, verfahren zu seiner herstellung und maschinenteile aus stahl mit hohem kohlenstoffgehalt

Info

Publication number
EP3848477B1
EP3848477B1 EP19817932.7A EP19817932A EP3848477B1 EP 3848477 B1 EP3848477 B1 EP 3848477B1 EP 19817932 A EP19817932 A EP 19817932A EP 3848477 B1 EP3848477 B1 EP 3848477B1
Authority
EP
European Patent Office
Prior art keywords
steel sheet
less
rolled steel
carbide
treatment
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.)
Active
Application number
EP19817932.7A
Other languages
English (en)
French (fr)
Other versions
EP3848477A1 (de
EP3848477A4 (de
Inventor
Eiji Tsuchiya
Yuta Matsumura
Hiroki Ota
Yuka Miyamoto
Yasuhiro Sakurai
Hideyuki Kimura
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.)
JFE Steel Corp
TOKUSHU KINZOKU EXCEL CO Ltd
Original Assignee
JFE Steel Corp
TOKUSHU KINZOKU EXCEL CO Ltd
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 JFE Steel Corp, TOKUSHU KINZOKU EXCEL CO Ltd filed Critical JFE Steel Corp
Publication of EP3848477A1 publication Critical patent/EP3848477A1/de
Publication of EP3848477A4 publication Critical patent/EP3848477A4/de
Application granted granted Critical
Publication of EP3848477B1 publication Critical patent/EP3848477B1/de
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • 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
    • 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
    • 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
    • C21D1/25—Hardening, combined with annealing between 300 degrees Celsius and 600 degrees Celsius, i.e. heat refining ("Vergüten")
    • 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
    • C21D1/26—Methods of annealing
    • 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
    • C21D1/26—Methods of annealing
    • C21D1/32—Soft annealing, e.g. spheroidising
    • 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
    • C21D1/58—Oils
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0236—Cold rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0247—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C21D8/0268—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment between cold rolling steps
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0247—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C21D8/0273—Final recrystallisation annealing
    • 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
    • C21D9/26—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for needles; for teeth for card-clothing
    • 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
    • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
    • 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
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium 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
    • C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
    • 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
    • C21D2211/004—Dispersions; Precipitations
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/008—Martensite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2261/00—Machining or cutting being involved

Definitions

  • the present invention relates to a high carbon cold rolled steel sheet serving as a material for various machine parts produced by quenching and tempering treatment and a method for manufacturing the high carbon cold rolled steel sheet, and relates particularly to a high carbon cold rolled steel sheet with a thickness of less than 1.0 mm applied to knitting needles and the like.
  • carbon steels for machine structural use SxxC
  • carbon tool steels (SK) specified in JIS are used for various types of machine parts. When used as flat-rolled materials, these steels are formed into a part shape through punching and various plastic processing, and quenching and tempering treatment is then carried out to impart a predetermined hardness and toughness (impact characteristics).
  • a knitting needle for knitting a knit fabric knits a knitting fabric by pulling yarn while repeating reciprocating motion at a high speed, so that a butt portion of a needle body coming into contact with a rotary driving part is required to have sufficient strength and wear resistance, and, in addition, a hook portion rubbing against the yarn is required to have excellent impact characteristics at its tip portion due to reciprocating motion in addition to sufficient wear resistance.
  • a high carbon cold rolled steel sheet used as a material for knitting needles is suitable for knitting needles for flat knitting machines when the thickness is 1.0 mm or more.
  • the high carbon cold rolled steel sheet is used for knitting needles for circular knitting machines and warp knitting machines. Since the latter needles knit small diameter yarns at high speed, the thickness of a material used is often 0.4 to 0.7 mm.
  • the material is required to have sufficient hardness and sufficient toughness at the needle tip when quenched and tempered after secondary working into a needle shape.
  • high carbon steel sheets such as carbon steels for machine structural use (SxxC) and carbon tool steels (SK) specified in JIS are classified in detail according to a C content.
  • a C content is less than 0.8% by mass, that is, a steel sheet with a hypo-eutectoid composition, since the fraction of the ferrite phase is high, the cold workability is excellent.
  • this steel sheet is not suitable for knitting needle applications that require wear resistance of a hook portion and durability of a needle body.
  • the material is subjected to a quenching and tempering treatment in order to ensure a predetermined hardness characteristic.
  • the temperature of the tempering treatment is a low temperature of 200 to 350°C.
  • a martensite phase is not sufficiently tempered, so that in some cases, the impact characteristics (toughness) are not sufficiently improved, and a toughness value may vary.
  • Patent Literature 1 describes "HIGH CARBON STEEL SHEET EXCELLENT IN HARDENABILITY, FATIGUE CHARACTERISTICS, AND TOUGHNESS AND METHOD FOR MANUFACTURING THE SAME".
  • the high carbon steel sheet described in Patent Literature 1 includes a composition containing, by mass%, C: 0.5 to 0.7%, Si: 0.5% or less, Mn: 1.0 to 2.0%, P: 0.02% or less, S: 0.02% or less, and Al: 0.001 to 0.10% and one or two or more elements selected from V: 0.05 to 0.50%, Ti: 0.02 to 0.20%, and Nb: 0.01 to 0.50%, with the balance being Fe and inevitable impurities, has a spheroidization rate of carbides is 95% or more, and has a structure in which the carbide having a maximum particle size of 2.5 ⁇ m or less is dispersed.
  • Patent Literature 1 For hypo-eutectoid steel, carbonitride forming elements V, Ti, and Nb are added to form fine carbonitrides. It is described that prior austenite grains are refined using the pinning effect of these fine carbonitrides to improve toughness.
  • Patent Literature 2 describes "HIGH CARBON STEEL MEMBER EXCELLENT IN IMPACT CHARACTERISTICS".
  • the high carbon steel member described in Patent Literature 2 has a composition consisting of, by mass%, C: 0.60 to 1.30%, Si: 1.0% or less, Mn: 0.2 to 1.5%, P: 0.02% or less, S: 0.02% or less, and the balance being Fe except inevitable impurities.
  • Patent Literature 2 describes that the high carbon steel member may, in addition to the above composition, contain, by mass%, one or two or more elements selected from Ni: 1.8% or less, Cr: 2.0% or less, V: 0.5% or less, Mo: 0.5% or less, Nb: 0.3% or less, Ti: 0.3% or less, B: 0.01% or less, and Ca: 0.01% or less.
  • Patent Literature 2 targets steels with a wide range of carbon content from hypo-eutectoid to hyper-eutectoid, it is described that it is possible to obtain a high carbon steel member exhibiting excellent impact characteristics with an impact value of 25 J/cm 2 or more while maintaining a target hardness of 600 to 900 HV.
  • Patent Literature 3 describes "HIGH CARBON COLD ROLLED STEEL SHEET AND METHOD FOR MANUFACTURING THE SAME".
  • the high carbon cold rolled steel sheet described in Patent Literature 3 contains, by mass%, C: 0.85 to 1.10%, Mn: 0.50 to 1.0%, Si: 0.10 to 0.35%, P: 0.030% or less, S: 0.030 % or less, Cr: 0.35 to 0.45%, and Nb: 0.005 to 0.020%, the balance being Fe and inevitable impurities.
  • An average particle diameter (d av ) of carbides dispersed in the steel sheet satisfies the following formula (1): 0.2 ⁇ d av ⁇ 0.7 ⁇ m and a spheroidization rate (N SC /N TC ) ⁇ 100% satisfies the following formula (2): N SC / N TC ⁇ 100 ⁇ 90 %
  • the high carbon cold rolled steel sheet has a thickness of less than 1.0 mm.
  • one or two elements selected from Mo and V are further contained in addition to the above-described composition, and each content is preferably 0.001% or more and less than 0.05%.
  • the content of Nb: 0.005 to 0.020% is effective for improving the hardenability and impact characteristics (toughness) after a short-time solution treatment and a low-temperature tempering treatment.
  • Patent Literature 4 describes "WEAR RESISTANT STEEL SHEET HAVING EXCELLENT TOUGHNESS".
  • the wear resistant steel sheet described in Patent Literature 4 has a chemical composition consisting of, by mass%, C: 0.60 to 1.25%, Si: 0.50% or less, Mn: 0.30 to 1.20%, P: 0.030% or less, S: 0.030% or less, Cr: 0.30 to 1.50%, Nb: 0.10 to 0.50%, Ti: 0 to 0.50%, Mo: 0 to 0.50%, V: 0 to 0.50%, Ni: 0 to 2.00%, the balance being Fe and inevitable impurities, and has a metal structure in which cementite particles and carbide particles containing one or more of Nb and Ti are dispersed in a metal matrix of a ferrite phase.
  • Patent Literature 4 describes that wear resistant steel sheet is a steel sheet having both excellent wear resistance and toughness.
  • a high carbon cold rolled steel sheet used as a material for knitting needles is required to have sufficient hardness and sufficient impact characteristics (toughness) after quenching and tempering treatment.
  • higher speeds of knitting machines have been demanded in order to improve productivity, so that load on the knitting needles has increased, and the knitting needles often break in a shorter time than conventional ones, or their service life is often shorter than conventional ones, which becomes problematic.
  • a knitting needle having improved impact characteristics and wear resistance.
  • Such a knitting needle is considered to be achieved by adding a third element or increasing the amount of alloy elements such as Cr, Mn, and Mo; however, there is a concern that the secondary workability in the needle manufacturing process is hindered. For these reasons, there is a demand for a material for knitting needles that can improve the wear resistance and impact characteristics (toughness) after quenching and tempering without lowering the secondary workability further than conventional one.
  • Patent Literature 1 is difficult to apply to machine parts that require high hardness.
  • the technique described in Patent Literature 1 is limited to hypo-eutectoid steel composition.
  • a carbonitride forming element such as V, Ti, and Nb as the third element, the prior austenite grains are refined with these fine carbonitrides, and the effect of improve toughness is expected.
  • the technique described in Patent Literature 1 is also a technique that improves formability of a ferrite matrix because the carbon level is a hypo-eutectoid composition.
  • Patent Literature 2 shows only an example for steel with a carbon content in the range of 0.67 to 0.81% by mass for the addition of Mo, V, Ti, Nb, and B as the third elements.
  • the third element such as Mo, V, Ti, Nb, and B is added to improve properties of hypo-eutectoid steel.
  • Patent Literature 2 does not describe anything about the action of the third element such as Mo, V, Ti, Nb, and B and the optimization for steel with a carbon content exceeding 0.81% by mass.
  • Patent Literature 1 and Patent Literature 2 do not describe a technique in which a high carbon cold rolled steel sheet is quenched after solution treatment for a short time such as 3 to 15 min and tempered at a low temperature of 200 to 350°C to advantageously improve desired impact characteristics and predetermined hardness.
  • Patent Literature 3 In the technique described in Patent Literature 3, it is described that the content of Nb: 0.005 to 0.020% is effective for improving the hardenability/impact characteristics (toughness) after quenching after holding solutionizing for a short time and a low-temperature tempering treatment; however, Patent Literature 3 does not specifically describe secondary workability of a high carbon cold rolled steel sheet before quenching (rapid cooling) after holding solutionizing for a short time and low-temperature tempering treatment (hereinafter, also referred to as quenching and tempering treatment). Patent Literature 3 describes a high carbon cold rolled steel sheet that can have both excellent toughness and excellent wear resistance after quenching and tempering treatment. However, this high carbon cold rolled steel sheet has a problem that the secondary workability before the quenching and tempering treatment is insufficient and it is not possible to meet recent demands for improving productivity.
  • Patent Literature 4 In the technique described in Patent Literature 4, it is described that in the high carbon cold rolled steel sheet, both wear resistance and toughness after quenching and tempering can be increased. However, there is no description about the secondary workability before the quenching and tempering treatment, and Patent Literature 4 does not mention that the wear resistance and toughness after quenching and tempering can be improved without lowering the secondary workability before quenching and tempering treatment.
  • an object of the present invention is to provide a high carbon cold rolled steel sheet which suppresses lowering of secondary workability before quenching (rapid cooling) after a short-time solution treatment and a low-temperature tempering treatment (quenching and tempering treatment), and, when evaluated by an impact test near an actually used sheet thickness after the quenching (rapid cooling) after the short-time solution treatment and the low-temperature tempering treatment (quenching and tempering treatment), has an impact value of 9 J/cm 2 or more, a hardness satisfying a range of 600 to 750 HV, excellent wear resistance, and a sheet thickness of less than 1.0 mm.
  • the present inventors have made intensive studies on a relationship of a composition of the high carbon cold rolled steel sheet with secondary workability before quenching and tempering treatment, hardness after the quenching and tempering treatment, impact characteristics, and wear resistance.
  • the high carbon cold rolled steel sheet of the present invention suppresses lowering of secondary workability such as a machinability, and the life of tools used for punching, swaging, bending, secondary working, etc. is comparable to that of a conventional high carbon cold rolled steel sheet.
  • a rapid cooling treatment after a short-time solution treatment and a low-temperature tempering treatment (quenching and tempering treatment) compared to conventional high-carbon steel sheets, it is possible to produce machine parts having a high balance of high hardness characteristics, excellent impact characteristics, and excellent wear resistance, which has a marked effect on the industry.
  • the high carbon cold rolled steel sheet of the present invention is excellent in impact characteristics (toughness), wear resistance, and fatigue resistance characteristics after quenching and tempering treatment, and particularly has an effect that the steel sheet is suitable for a material for machine parts that requires excellent durability in a severe use environment, such as a knitting needle.
  • a high carbon cold rolled steel sheet of the present invention is a high carbon cold rolled steel sheet as defines in claim 1.
  • This steel sheet has a sheet thickness of less than 1.0 mm .
  • C is an essential element for obtaining sufficient hardness (600 to 750 HV) with precision parts such as knitting needles after heat treatment (quenching and tempering treatment).
  • the content of C needs to be 0.85% or more.
  • the amount of C increases, the amount of carbide increases, cold workability is lowered, and it becomes impossible to withstand various plastic working (cold working) such as punching, swaging, bending, and secondary working.
  • the cold workability is improved by repeating cold rolling and spheroidizing annealing, and spheroidizing the carbide; however, if more than 1.10% C is contained, problems in manufacturing process become apparent, for example, when rolling load increases in a hot rolling process and a cold rolling process, or when a frequency of cracks at coil ends remarkably increases. Therefore, the amount of C is limited to 0.85% or more and 1.10% or less. The amount of C is preferably 0.95 to 1.05%.
  • Mn is an element that effectively acts on deoxidation of steel, and can improve hardenability of steel and stably ensure a predetermined hardness.
  • the content is 0.60% or more, MnS inclusions increase, which adversely affects secondary workability before quenching and tempering treatment.
  • cleanliness, particularly dA is 0.10% or more, probability of inclusions hitting a cutting blade increases, the cutting resistance is increased, and the secondary workability is significantly deteriorated.
  • Mn is limited to 0.50% or less as a range where dA is less than 0.10%.
  • the cleanliness is measured according to JIS G 0555.
  • an attention is paid to dA especially for A-type inclusions.
  • Si 0.10% or more and 0.35% or less
  • Si acts as a deoxidizer for molten steel and is an effective element for producing clean steel.
  • Si is an element that contributes to tempering softening resistance of martensite. In order to obtain such an effect, the content of 0.10% or more is required.
  • a large amount of Si exceeding 0.35% results in insufficient tempering of martensite during low-temperature tempering treatment, and impact characteristics are deteriorated. For these reasons, Si is limited to the range of 0.10% or more and 0.35% or less.
  • Both P and S are elements that are unavoidably present in steel and adversely affect impact characteristics. Although it is desirable to reduce P and S as much as possible, it is practically acceptable so long as the content of P is up to 0.030% and the content of S is up to 0.030%. For these reasons, P is limited to 0.030% or less, and S is limited to 0.030% or less. From the viewpoint of maintaining excellent impact characteristics, it is preferable to adjust P to 0.020% or less and S to 0.020% or less.
  • Cr is an element that improves hardenability of steel and is solid-dissolved in carbide (cementite) to harden the carbide, thereby contributing to improvement of wear resistance.
  • carbide cementite
  • the residual carbide refers to, among carbides which were not able to be completely solved into a base matrix during heating and holding during quenching treatment, the carbide remaining in the base matrix after rapid cooling for martensitic transformation. As residual carbides increase, wear resistance improves.
  • Cr is limited to less than 0.50%. Cr is preferably 0.10% or more.
  • Nb 0.005% or more and 0.020% or less
  • Nb is an element that enlarges an unrecrystallization temperature range of steel during hot rolling, mainly in low-carbon steel, at the same time, is precipitated as NbC, and contributes to refinement of austenite grains. Also in high carbon steel, Nb may be added in anticipation of a structure refining effect after the cold rolling process.
  • Nb is contained in an amount of 0.005% or more and 0.020% or less mainly for the purpose of recovering toughness by low-temperature tempering after quenching. If the Nb content is small, NbC contributing to structure refinement is not formed, and Nb is in a dilute solid solution state.
  • Nb was limited to 0.005% or more and 0.020% or less.
  • Nb is preferably 0.015% or less.
  • the total of the Mn content and the Cr content (Mn + Cr) is adjusted to less than 0.90%.
  • Mn + Cr the total of the Mn content and the Cr content
  • an effect of delaying re-dissolution of the carbide in the heating stage during quenching is greater than in a case that Mn alone is used and Cr alone is used, residual carbides increase, and the wear resistance also increases.
  • the residual carbide when (Mn + Cr) increases to 1.0% or more, the residual carbide becomes 6% or more in terms of area ratio, the effect of hardenability deterioration increases, and an impact value (toughness) after quenching and tempering also decreases. If (Mn + Cr) is less than 1%, the residual carbide is less than 6% in terms of area ratio, and it is possible to provide both excellent wear resistance and toughness. On the other hand, if (Mn + Cr) is too small, the residual carbides decreases, and desired wear resistance cannot be ensured.
  • the residual carbide is preferably 3% or more in terms of area ratio.
  • (Mn + Cr) for achieving the amount of the residual carbides of 3% or more in terms of area ratio is preferably 0.15% or more.
  • the above-described components are basic components, in addition to the basic components, one or two selected from Mo: 0.001% or more and less than 0.05% and V: 0.001% or more and less than 0.05% may be contained as selected elements.
  • Mo and V as one or two selected from Mo: 0.001% or more and less than 0.05% and V: 0.001% or more and less than 0.05% are both elements contributing to improvement in the hardenability of steel and improvement in impact characteristics (toughness) after quenching and tempering treatment, and one or two selected as necessary can be contained in an amount greater than an unavoidably contained level (0.001%).
  • Mo is an element effective for improving the hardenability of steel, if the Mo content is 0.05% or more, the effect of delaying dissolution of carbides increases, so that the hardenability is further lowered and sufficient hardness is not obtained. In addition, the effect of Nb is lost, and the impact characteristics after low-temperature tempering are reduced.
  • Mo is preferably limited to 0.001% or more which is the inevitably contained level or more, and less than 0.05%, Mo is preferably 0.01% or more and 0.03% or less.
  • V is an element that contributes to improvement in impact characteristics through refinement of a steel structure
  • a large amount, 0.05% or more, of V is contained, the effect of delaying dissolution of carbides increases, so that the hardenability is further lowered and sufficient hardness is not obtained.
  • the effect of Nb is lost, and the impact characteristics after low-temperature tempering treatment are reduced.
  • V is preferably limited to 0.001% or more which is the inevitably contained level or more, and less than 0.05%
  • Mo is preferably 0.01% or more and 0.03% or less.
  • the balance other than the above components contains Fe and inevitable impurities.
  • the high carbon cold rolled steel sheet of the present invention has the above-described composition and a structure in which a carbide having an average particle diameter (d av ) ( ⁇ m) satisfying the following formula (1): 0.2 ⁇ d av ⁇ 0.7 ⁇ m and a spheroidization rate (N SC /N TC ) satisfying the following formula (2): N SC / N TC ⁇ 100 ⁇ 90 % is dispersed.
  • the average particle diameter (d av ) in the formula (1) is an average value of diameters of individual circles (equivalent circle diameters) when assuming a circle having the same area as each carbide observed in a cross section of the steel sheet.
  • the average particle diameter (d av ) of the dispersed carbide is in a range satisfying the formula (1), the impact characteristics are excellent, and, in addition, there is an effect that desired quenching hardness can be easily secured even in a rapid cooling (quenching) treatment after a short-time solution treatment.
  • the average particle diameter (d av ) of the dispersed carbide is less than 0.2 ⁇ m, the carbide becomes finer, and the number of dispersed carbides increases, so that load of secondary working on a needle shape increases.
  • the average particle diameter (d av ) exceeds 0.7 ⁇ m, it is difficult to secure desired quenching hardness in the rapid cooling treatment after the short-time solution treatment.
  • the spheroidization rate is defined by (N SC /N TC ) in the formula (2).
  • N TC is a total number of carbides per observed area of 100 ⁇ m 2
  • N SC is a number of carbides regarded as spheroidized in the same observation field and is the number of carbides satisfying a condition of d L /d S ⁇ 1.4.
  • the major axis of the carbide is d L and the minor axis is d S .
  • the carbide is completely formed into a spherical shape, and the carbide is often observed as an elliptical shape depending on the observed surface, so that a degree of spheroidization is specified by a ratio (d L /d S ) of the major axis to the minor axis.
  • carbides satisfying a condition of (d L /d S ): 1.4 or less are defined as spheroidized carbides, and the number thereof is N SC . From empirical knowledge, it is necessary that the spheroidization rate (N SC /N TC ) ⁇ 100 is 90% or more in order to keep good secondary workability of the steel sheet.
  • the average particle diameter and spheroidization rate of the carbides described above were calculated by observing a secondary electron microscope image (magnification: 2000 times) using a scanning electron microscope and performing image analysis.
  • a test piece for carbide observation was sampled from a cold rolled steel sheet (sheet-thickness central portion), embedded in resin, polished, and etched with an etching solution, and the carbide was observed using a scanning electron microscope.
  • the equivalent circle diameter, the ratio of the major axis d L to the minor axis d S , N TC , and N SC of the carbide were measured in the range of the observed area of 100 ⁇ m 2 near the sheet-thickness central portion. Such measurement was carried out for five fields of view, and each average value was calculated. For these measurements and calculations, commercially available image analysis software winroof was used.
  • the high carbon cold rolled steel sheet of the present invention has the above-described steel sheet composition and structure, and while secondary workability such as a machinability is held, the life of tools used for punching, swaging, bending, secondary working, etc. is comparable to that of a conventional high carbon cold rolled steel sheet.
  • a rapid cooling treatment after a short-time solution treatment and a low-temperature tempering treatment (quenching and tempering treatment) compared to conventional high-carbon steel sheets, it is possible to produce machine parts having a high balance of high hardness characteristics, excellent impact characteristics, and excellent wear resistance.
  • excellent in secondary workability refers to that, as shown in Fig. 1 , when a cutting (end milling) test is performed, a force applied to a tool (end mill) is less than 40 N (tool rotational speed is low (1300 rpm)) or less than 35 N (tool rotational speed is high (2300 rpm)).
  • a steel sheet (work material) was subjected to cutting work (end milling) using an end mill.
  • an X-direction component force, a Y-direction component force, and a Z-direction component force as cutting resistance forces applied to the tool were measured by a cutting dynamometer (not shown) attached to the tool, and the resultant force was calculated and used as a secondary workability evaluation index.
  • the conditions of the endmill working test were: cutting speed 25 m/min (low speed), 45 m/min (high speed); feed amount per blade 0.016 mm/touth; cut amount 0.2mm; tool protrusion length 25mm; cutting distance 30 mm, and no cutting oil was used.
  • the secondary workability can be evaluated in a state closer to an actual use environment. If the cutting resistance force applied to the tool is less than 40 N (or less than 35 N), it means to provide excellent secondary workability equal to or better than the secondary workability of conventional high carbon cold rolled steel sheets.
  • excellent wear resistance refers to a case where a wear test using a wear testing machine shown in Fig. 2 is performed and the obtained wear depth is less than 485 ⁇ m.
  • a wear testing machine 10 shown in Fig. 2 includes a yarn unwinding device 11 for unwinding yarn, a tension adjusting means 12 for applying a desired tension to unwound yarn 2, a wear test piece 1 having holes 1a to 1d for passing the tensioned yarn, and a yarn winding device 13 for winding the yarn and can reproduce wear of a knitting needle due to knitting yarn in a situation close to an actual machine.
  • the wear testing machine 10 has a structure in which the tension is zero when the yarn breaks, and the machine automatically stops at that point.
  • the wear test piece 1 to be used is a wear test piece having the shape shown in Fig. 3(a) , and the yarn 2 continuously unwound from a bobbin (yarn unwinding device) 11 is subjected to a proper tension by the tension adjusting means 12. Then, the yarn 2 passes through, for example, the hole 1a formed in the wear test piece 1 and is wound by the yarn winding device 13 while being in contact with the hole 1a to wear the hole 1a.
  • Four holes (1a to 1d) were formed per one test piece.
  • the conditions for the wear test were: polyester full dull knitting yarn (standard 110T48); yarn feed speed 160 m/s; tension 10 ⁇ 2 N/cm.
  • the wear test was performed until the yarn with a length of 100,000 m was fed out from one hole, and the wear depth in the hole was measured. Such a wear test was performed on each of the four holes 1a to 1d formed in one wear test piece, the wear depth of each hole was measured, and the average value thereof was taken as the wear depth (average) of the wear test piece.
  • the wear resistance can be evaluated in a state close to wear due to yarn of a hook portion of a knitting needle. It was found that the wear resistance was evaluated in the state close to the wear due to the yarn of the hook portion of the knitting needle, so that presence of residual carbides greatly affected the wear resistance.
  • the wear resistance is proportional to the area ratio of the residual carbide. If the residual carbide is less than 3% in terms of area ratio, desired wear resistance cannot be ensured.
  • the residual carbide is preferably 3% or more in terms of area ratio.
  • excellent impact characteristics refers to a case where an impact test piece (a U-notch test piece with a notch width of 0.2 mm (notch depth 2.5 mm, notch radius 0.1 mm)) shown in Fig. 4 was used, and when a test was performed at room temperature and at a supporting bed distance of 40 mm as shown in Fig. 5 by a Charpy impact tester (Toyo Seiki Seisaku-sho, Ltd. model DG-GB) with a rated capacity of 1 J based on JIS K 7077, an impact value was 9 J/cm 2 or more.
  • a Charpy impact tester Toyo Seiki Seisaku-sho, Ltd. model DG-GB
  • the high carbon cold rolled steel sheet of the present invention is manufactured by applying softening annealing to a hot rolled steel sheet as necessary, and repeatedly performing cold rolling and spheroidizing annealing.
  • the hot rolled steel sheet used in the present invention may be one obtained under normal manufactured conditions.
  • a steel piece (slab) having the above-described composition is heated to 1050 to 1250°C, hot rolled at a finishing temperature of 800 to 950°C, and formed into a coil at a coiling temperature of 600 to 750°C, whereby the hot rolled steel sheet can be produced.
  • the sheet thickness of the hot rolled steel sheet may be appropriately set from the sheet thickness of a desired cold rolled steel sheet such that a suitable reduction rate in cold rolling is obtained.
  • the hot rolled steel sheet is repeatedly subjected to cold rolling and spheroidizing annealing multiple times to obtain a high carbon cold rolled steel sheet having a sheet thickness of less than 1.0 mm.
  • the cold rolling and spheroidizing annealing are repeated 2 to 5 times.
  • the reduction rate in cold rolling is in a range of 25 to 65%. If a steel sheet (cold rolled steel sheet) with a cold rolling reduction rate of less than 25% is subjected to spheroidizing annealing, carbides become coarse. On the other hand, if the reduction rate in cold rolling exceeds 65%, load of cold rolling operation may be too large. Thus, the reduction rate in cold rolling is limited to the range of 25 to 65%. For a final cold rolling which does not give spheroidizing annealing after cold rolling, the lower limit of the reduction rate is not particularly limited.
  • the spheroidizing annealing is performed at a temperature in a range of 640 to 720°C. If the spheroidizing annealing temperature is less than 640°C, spheroidization tends to be insufficient, whereas if the temperature is higher than 720°C, carbides tend to become coarse. Thus, the spheroidizing annealing is performed at a temperature in the range of 640 to 720°C. A holding time of the spheroidizing annealing is preferably selected as appropriate in a range of 9 to 30 hr.
  • N SC /N TC carbide spheroidization rate
  • Particularly preferred are cold rolling from twice to five times and spheroidizing annealing from twice to five times.
  • the same temperature range is preferable for softening annealing aiming at softening of a hot rolled steel sheet before cold rolling.
  • the above method is the method for manufacturing the high carbon cold rolled steel sheet of the present invention.
  • this steel sheet In order to form this steel sheet into a machine part such as a knitting needle as a final object, it is preferable to form the steel sheet into a predetermined shape and then perform the following heat treatment.
  • a high carbon cold rolled steel sheet in which carbide spheroidized by 90% or more is distributed is processed into various machine parts, then subjected to a rapid cooling (quenching) treatment after solution treatment, and subsequently subjected to tempering treatment.
  • the heating temperature is 760 to 820°C
  • the holding time is a short time such as 3 to 15 min. Oil is used for quenching (rapid cooling).
  • the tempering temperature is 200 to 350°C.
  • the tempering temperature is preferably 250 to 300°C.
  • the holding time of the solution treatment is longer than 15 min, the carbide is excessively dissolved, and austenite grains become coarse, so that the martensite phase after quenching becomes coarse and impact characteristics are deteriorated.
  • the holding time is shorter than 3 min, the carbide is not sufficiently dissolved, and it is difficult to obtain a desired high hardness after rapid cooling.
  • the holding time of the solution treatment is 3 min or more and 15 min or less. The holding time is more preferably 5 to 10 min.
  • the tempering temperature is in a range of 200 to 350°C.
  • the tempering temperature is more preferably 250 to 300°C.
  • a holding time of tempering treatment is preferably selected as appropriate in a range of 30 min to 3 hr.
  • Molten steel having the chemical components shown in Table 1 was melted in a vacuum melting furnace and then cast into a mold to obtain small-size steel ingots (50 kgf). These small-size steel ingots were slabbed, formed into steel pieces, and then hot-rolled under conditions of a heating temperature of 1150°C and a rolling finishing temperature of 870°C to form a hot rolled steel sheet (sheet thickness: 4 mm). Subsequently, the obtained hot rolled steel sheet was subjected to cold rolling and spheroidizing annealing under the conditions shown in Table 2 to obtain a cold rolled steel sheet having a sheet thickness of 0.4 mm or more and less than 1.0 mm.
  • a test piece for structure observation was collected from the obtained cold rolled steel sheet, embedded in resin, polished and etched, and a structure was observed from a secondary electron microscope image (magnification: 2000 times) using a scanning electron microscope and imaged.
  • the average particle diameter (d av ) and the spheroidization rate (N SC /N TC ) of the carbide were calculated by image analysis.
  • the equivalent circle diameter of each carbide and the ratio of the major axis d L to the minor axis d S of each carbide were determined, and the total number N TC of carbides per observed area of 100 ⁇ m 2 and the total number N SC of carbides satisfying the condition of d L /d S : 1.4 or less were measured.
  • Such measurement was carried out for five fields of view, and their average values were calculated.
  • commercially available image analysis software winroof was used.
  • cleanliness dA was measured for A-type inclusions in accordance with JIS G 0555.
  • the measurement visual field was 60 visual fields.
  • a test piece was collected from the obtained cold rolled steel sheet, and under the conditions shown in Table 3, as shown in Fig. 1 , a machinability test (endmill working test) was performed. After forces in the X direction, the Y direction, and the Z direction applied to a tool (end mill: 6 mm diameter) were measured, the resultant force was calculated and used as the cutting resistance force. Two types of rotational speeds of the tool were a low speed (1300 rpm) and a high speed (2300 rpm).
  • the obtained cold rolled steel sheet was charged into a heating furnace and subjected to a short-time solution treatment under the conditions shown in Table 4, and then subjected to a rapid cooling (oil quenching) treatment.
  • heat treatment that applies a low-temperature tempering treatment was performed.
  • a test piece was collected from the heat-treated steel sheet and subjected to residual carbide investigation, hardness test, impact test, and wear test. The test method was as follows.
  • a test piece for structure observation was collected from the heat-treated steel sheet, embedded in resin, polished and etched, and a structure was observed from a secondary electron microscope image (magnification: 2000 times) using a scanning electron microscope and imaged, and by image analysis, the area ratio (%) of residual carbide was calculated for residual carbide having an equivalent circle diameter of 0.1 ⁇ m or more.
  • the measurement area was 100 ⁇ m 2 .
  • a hardness test piece was cut out from the heat-treated steel sheet in a direction perpendicular to a rolling direction and embedded in resin, the cross section was polished, and the hardness was measured at the sheet-thickness central portion. The hardness was measured at five points for each piece in accordance with JIS Z 2244 using a Vickers hardness tester (test force: 49.0 N), and the average value thereof was taken as the hardness of the steel sheet.
  • a wear test piece having the shape shown in Fig. 3 was collected from the heat-treated steel sheet and subjected to the wear test using the wear testing machine shown in Fig. 2 .
  • the conditions for the wear test were: polyester full dull knitting yarn (standard 110T48); yarn feed speed 160 m/s; tension 10 ⁇ 2 N/cm. After the yarn was run through 100,000 m in one hole, the testing machine was stopped, and the wear depth formed in the hole (1a in this case) of the wear test piece 1 as shown in Fig. 3(b) was measured with an optical microscope. Such a wear test was performed on each hole (1a to 1d), the wear depth of each hole (four holes) was measured, and the average value thereof was obtained and taken as the wear depth of the wear test piece.
  • All of the examples of the present invention provide high carbon cold rolled steel sheets in which the force (cutting resistance) applied to the tool was less than 40 N at low speed working and less than 35 N at high speed working, and the secondary workability was equivalent to that of a conventional high carbon cold rolled steel sheet.
  • the high carbon cold rolled steel sheet After rapid cooling (oil quenching) treatment after short-time solution treatment and low-temperature tempering treatment, the high carbon cold rolled steel sheet had high hardness characteristics satisfying a hardness range of 600 to 750 HV, the impact value satisfied 9 J/cm 2 or more, and the impact characteristics were excellent.
  • the high carbon cold rolled steel sheet had a wear depth of less than 485 ⁇ m, thus was excellent in wear resistance, and was evaluated as " ⁇ ".
  • the force (cutting resistance) applied to the tool is 40 N or more at low speed working and 35 N or more at high speed working, and the secondary workability is poor.
  • the impact value is less than 9 J/cm 2 , and thus impact characteristics are deteriorated.
  • the high carbon cold rolled steel sheet has a wear depth of 485 ⁇ m or more, thus has lowered wear resistance, and is evaluated as " ⁇ ".
  • Comparative Example (steel sheet No. 1) in which the C content is lower than the range of the present invention the cutting resistance is low, and the secondary workability is excellent.
  • the impact value is 9 J/cm 2 or more, and thus the impact characteristics are excellent.
  • the amount of residual carbide is small, the wear depth is 485 ⁇ m or more, and thus the wear resistance is lowered.
  • Comparative Example (steel No. 12) in which the C content is higher than the range of the present invention the amount of residual carbide is large.
  • the wear depth is less than 485 ⁇ m, and thus the wear resistance is excellent.
  • the impact value is less than 9 J/cm 2 , and thus the impact characteristics are deteriorated.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Heat Treatment Of Sheet Steel (AREA)
  • Heat Treatment Of Articles (AREA)

Claims (3)

  1. Ein kaltgewalztes Stahlblech mit hohem Kohlenstoffgehalt, das eine Stahlblechzusammensetzung aufweist, in Masse-%,
    C: 0,85% oder mehr und 1,10% oder weniger, Mn: 0,50% oder weniger,
    Si: 0,10 % oder mehr und 0,35 % oder weniger, P: 0,030 % oder weniger,
    S: 0,030% oder weniger, Cr: weniger als 0,50%, und
    Nb: 0,005 % oder mehr und 0,020 % oder weniger,
    eine Summe aus einem Mn-Gehalt und einem Cr-Gehalt (Mn + Cr), die weniger als 0,90% beträgt,
    gegebenenfalls, in Masse-%, ein oder zwei Elemente, ausgewählt aus
    Mo: 0,001% oder mehr und weniger als 0,05% und V: 0,001% oder mehr und weniger als 0,05%, und wobei der Rest Fe und unvermeidbare Verunreinigungen sind, wobei die Dicke des Stahlblechs weniger als 1,0 mm beträgt, und ferner eine Stahlblechstruktur aufweist, in der ein durchschnittlicher Teilchendurchmesser dav und eine Sphäroidisierungsrate (NSC/NTC) × 100% des in einem Stahlblech dispergierten Karbids die folgenden Formeln (1) bzw. (2) erfüllen: 0 , 2 ≤ d av ≤ 0 , 7 μm N SC / N TC × 100 ≥ 90 %
    wobei dav ein Durchschnittswert eines äquivalenten Kreisdurchmessers des Hartmetalls, gemessen in µm, ist,
    NTC die Gesamtzahl der Karbide pro beobachteter Fläche von 100 µm2ist, und
    NSC eine Anzahl der Karbide ist, die eine Bedingung erfüllen, bei der (Hauptachse dL) /(Nebenachse dS) pro beobachteter Fläche von 100 µm2 1,4 oder weniger ist, und wobei der durchschnittliche Teilchendurchmesser dav und die Sphäroidisierungsrate (NSC/NTC) × 100% des in einem Stahlblech dispergierten Karbids nach den in der Beschreibung beschriebenen Verfahren gemessen werden.
  2. Ein Verfahren zur Herstellung eines kaltgewalzten Stahlblechs mit hohem Kohlenstoffgehalt weist das wiederholte Anwenden von Kaltwalzen und sphäroidisierendem Glühen auf ein warmgewalztes Stahlblech mit der Stahlblechzusammensetzung nach Anspruch 1 auf,
    wobei die Anzahl der Wiederholungen des Kaltwalzens und des sphäroidisierenden Glühens 2 bis 5 Mal beträgt,
    wobei die Reduktionsrate beim Kaltwalzen 25 bis 65% beträgt und die Temperatur des Kugelglühens 640 bis 720°C beträgt,
    wobei ein durchschnittlicher Teilchendurchmesser dav und eine Sphäroidisierungsrate (NSC/NTC) von in dem kaltgewalzten Stahlblech mit hohem Kohlenstoffgehalt dispergiertem Karbid die folgenden Formeln (1) bzw. (2) erfüllen: 0 , 2 ≤ d av ≤ 0 , 7 μm N SC / N TC × 100 ≥ 90 %
    wobei dav ein Durchschnittswert eines äquivalenten Kreisdurchmessers des Karbids, gemessen in µm, ist,
    NTC die Gesamtzahl der Karbide pro beobachteter Fläche von 100 µm2ist, und
    NSC die Anzahl der Karbide ist, die eine Bedingung erfüllen, bei der (Hauptachse dL) /(Nebenachse dS) pro beobachteter Fläche von 100 µm2 1,4 oder weniger ist, und
    die Blechdicke des kaltgewalzten Stahlblechs mit hohem Kohlenstoffgehalt weniger als 1,0 mm beträgt, und wobei
    der durchschnittliche Teilchendurchmesser dav und die Sphäroidisierungsrate (NSC/NTC) × 100 % des in einem Stahlblech dispergierten Karbids unter Verwendung der in der Beschreibung beschriebenen Verfahren gemessen werden.
  3. Ein Verfahren zum Herstellen eines Maschinenteils aus kohlenstoffreichem Stahl, das aufweist: Anwenden einer sekundären Bearbeitung auf das kaltgewalzte Stahlblech mit hohem Kohlenstoffgehalt gemäß Anspruch 1 als ein Material, um das Stahlblech zu einem Maschinenteil mit einer vorbestimmten Form zu formen; und Anwenden einer Schnellabkühlungsbehandlung, wobei die Schnellabkühlung eine Ölabschreckung ist, nach einer Kurzzeitlösungsbehandlung und einer Anlaßbehandlung auf das Maschinenteil, wobei
    die Schnellkühlbehandlung nach der Kurzzeitlösungsbehandlung eine Behandlung ist, bei der das Maschinenteil bei einer Temperatur in einem Bereich von 760 bis 820°C für eine Zeit in einem Bereich von 3 bis 15 Minuten gehalten und schnell abgekühlt wird, und die Anlassbehandlung eine Behandlung ist, bei der das Anlassen bei einer Temperatur in einem Bereich von 200 bis 350°C durchgeführt wird, um dem Maschinenteil sowohl eine ausgezeichnete Verschleißfestigkeit als auch eine ausgezeichnete Zähigkeit zu verleihen.
EP19817932.7A 2019-11-08 2019-11-08 Kaltgewalztes stahlblech mit hohem kohlenstoffgehalt, verfahren zu seiner herstellung und maschinenteile aus stahl mit hohem kohlenstoffgehalt Active EP3848477B1 (de)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/JP2019/043828 WO2021090472A1 (ja) 2019-11-08 2019-11-08 高炭素冷延鋼板およびその製造方法並びに高炭素鋼製機械部品

Publications (3)

Publication Number Publication Date
EP3848477A1 EP3848477A1 (de) 2021-07-14
EP3848477A4 EP3848477A4 (de) 2022-05-25
EP3848477B1 true EP3848477B1 (de) 2025-09-17

Family

ID=75849823

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19817932.7A Active EP3848477B1 (de) 2019-11-08 2019-11-08 Kaltgewalztes stahlblech mit hohem kohlenstoffgehalt, verfahren zu seiner herstellung und maschinenteile aus stahl mit hohem kohlenstoffgehalt

Country Status (6)

Country Link
EP (1) EP3848477B1 (de)
JP (1) JP6880245B1 (de)
KR (1) KR102329386B1 (de)
CN (1) CN113099723B (de)
TW (1) TWI734291B (de)
WO (1) WO2021090472A1 (de)

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2022264947A1 (ja) * 2021-06-18 2022-12-22 Ｊｆｅスチール株式会社 冷延鋼板、鋼製部品、冷延鋼板の製造方法、および鋼製部品の製造方法
WO2022264948A1 (ja) * 2021-06-18 2022-12-22 Ｊｆｅスチール株式会社 鋼製部品および鋼製部品の製造方法
CN114055082B (zh) * 2021-11-15 2024-02-06 江苏九天光电科技有限公司 一种钩针用优特钢精密钢带的生产方法
CN114855076B (zh) * 2022-04-15 2023-03-17 首钢集团有限公司 一种高球化率高碳钢及其制备方法
CN114850436B (zh) * 2022-05-06 2023-05-09 上海交通大学 一种高碳高合金钢的碳化物细化方法
CN114774795A (zh) * 2022-05-09 2022-07-22 湖南华菱涟钢特种新材料有限公司 一种超高碳素工具钢热轧钢板及其生产方法
WO2024141228A1 (en) * 2022-12-30 2024-07-04 Hilti Aktiengesellschaft Steel alloy, article of manufacture and method
EP4435132A1 (de) * 2023-03-22 2024-09-25 Hilti Aktiengesellschaft Stahllegierung, herstellungsgegenstand und verfahren
JP7748078B1 (ja) * 2023-11-06 2025-10-02 Ｊｆｅスチール株式会社 鋼製部品およびその製造方法

Family Cites Families (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4492105B2 (ja) * 2003-11-28 2010-06-30 Ｊｆｅスチール株式会社 伸びフランジ性に優れた高強度冷延鋼板の製造方法
JP4530268B2 (ja) 2004-08-26 2010-08-25 日新製鋼株式会社 衝撃特性に優れた高炭素鋼部材及びその製造方法
CN1772939A (zh) * 2005-11-17 2006-05-17 上海隆兴特钢有限公司 高纯净钢纺织针用钢带及其生产方法
JP5030280B2 (ja) 2007-07-20 2012-09-19 日新製鋼株式会社 焼入れ性、疲労特性、靭性に優れた高炭素鋼板及びその製造方法
KR101128942B1 (ko) * 2008-12-24 2012-03-27 주식회사 포스코 열처리 특성이 우수한 미세구상화 강판 및 그 제조방법
WO2012036483A2 (ko) * 2010-09-16 2012-03-22 주식회사 포스코 고탄소 열연강판, 냉연강판 및 그 제조방법
WO2013047821A1 (ja) * 2011-09-30 2013-04-04 新日鐵住金株式会社 焼付硬化性に優れた高強度溶融亜鉛めっき鋼板、高強度合金化溶融亜鉛めっき鋼板、並びにそれらの製造方法
CN103290308B (zh) * 2012-02-27 2017-04-12 株式会社神户制钢所 高强度冷轧钢板及其制造方法
CN105378127B (zh) * 2013-06-27 2018-09-21 日新制钢株式会社 疲劳特性优良的耐磨性钢材及其制造方法
US10407748B2 (en) * 2013-11-22 2019-09-10 Nippon Steel Corporation High-carbon steel sheet and method of manufacturing the same
WO2017010008A1 (ja) * 2015-07-16 2017-01-19 日新製鋼株式会社 繊維機械部品用鋼板およびその製造方法
JP6089131B2 (ja) * 2015-08-14 2017-03-01 株式会社特殊金属エクセル 高炭素冷延鋼板及びその製造方法
JP6615039B2 (ja) 2016-04-13 2019-12-04 日鉄日新製鋼株式会社 靭性に優れる耐摩耗性鋼板
CN110306027A (zh) * 2019-07-02 2019-10-08 浙江豪环新材料有限公司 一种t8碳素钢冷轧生产工艺

Also Published As

Publication number Publication date
WO2021090472A1 (ja) 2021-05-14
CN113099723A (zh) 2021-07-09
TWI734291B (zh) 2021-07-21
KR20210056880A (ko) 2021-05-20
EP3848477A1 (de) 2021-07-14
EP3848477A4 (de) 2022-05-25
JPWO2021090472A1 (ja) 2021-11-25
JP6880245B1 (ja) 2021-06-02
CN113099723B (zh) 2023-02-17
TW202118881A (zh) 2021-05-16
KR102329386B1 (ko) 2021-11-19

Similar Documents

Publication Publication Date Title
EP3848477B1 (de) Kaltgewalztes stahlblech mit hohem kohlenstoffgehalt, verfahren zu seiner herstellung und maschinenteile aus stahl mit hohem kohlenstoffgehalt
CN107208224B (zh) 高碳冷轧钢板及其制造方法
JP5484103B2 (ja) 高強度機械部品用素材鋼板およびその製造方法並びに高強度機械部品製造方法
US20120018063A1 (en) Case-hardened steel superiorin cold workability, machinability, and fatigue characteristics after carburized quenching and method of production of same
KR20130125816A (ko) 기소강 및 그의 제조 방법, 및 기소강을 이용한 기계 구조 부품
JP4465057B2 (ja) 精密打抜き用高炭素鋼板
JP5280324B2 (ja) 精密打抜き用高炭素鋼板
JP2008081841A (ja) 冷間鍛造性および結晶粒粗大化防止特性に優れた肌焼鋼およびそれから得られる機械部品
JP2003147485A (ja) 加工性に優れた高靭性高炭素鋼板およびその製造方法
US10533235B2 (en) Hot-working tool material, method for manufacturing hot-working tool, and hot-working tool
JP3737323B2 (ja) 球状化後の冷間鍛造性に優れた鋼線材・棒鋼およびその製造方法
JP4159009B2 (ja) 疲労特性に優れた打抜き部品用鋼板
JP7626165B2 (ja) 鋼製部品の製造方法
JP4161090B2 (ja) 打抜き性に優れた高炭素鋼板
JP4330090B2 (ja) 鋼製リクライニングシートギア
JP4121416B2 (ja) 機械構造用非調質型熱間鍛造部品およびその製造方法
JP7748018B2 (ja) 鋼板
JP4266052B2 (ja) 局部延性に優れた高加工性高炭素鋼板
JP2005336560A (ja) 精密打抜き部品用高炭素鋼板および精密打抜き部品
WO2025079651A1 (ja) 鋼板
JP4266051B2 (ja) 局部延性に優れた高加工性高炭素鋼板
WO2025100150A1 (ja) 鋼製部品およびその製造方法

Legal Events

Date Code Title Description
STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: UNKNOWN

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE INTERNATIONAL PUBLICATION HAS BEEN MADE

PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: REQUEST FOR EXAMINATION WAS MADE

17P Request for examination filed

Effective date: 20191220

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

REG Reference to a national code

Ref country code: DE

Ref legal event code: R079

Free format text: PREVIOUS MAIN CLASS: C22C0038000000

Ipc: C21D0009460000

Ref document number: 602019075896

Country of ref document: DE

A4 Supplementary search report drawn up and despatched

Effective date: 20220425

RIC1 Information provided on ipc code assigned before grant

Ipc: C21D 8/02 20060101ALI20220419BHEP

Ipc: C22C 38/24 20060101ALI20220419BHEP

Ipc: C22C 38/22 20060101ALI20220419BHEP

Ipc: C22C 38/04 20060101ALI20220419BHEP

Ipc: C22C 38/02 20060101ALI20220419BHEP

Ipc: C21D 9/26 20060101ALI20220419BHEP

Ipc: C21D 1/58 20060101ALI20220419BHEP

Ipc: C21D 1/32 20060101ALI20220419BHEP

Ipc: C21D 1/26 20060101ALI20220419BHEP

Ipc: C21D 1/25 20060101ALI20220419BHEP

Ipc: C21D 1/18 20060101ALI20220419BHEP

Ipc: C22C 38/12 20060101ALI20220419BHEP

Ipc: C22C 38/26 20060101ALI20220419BHEP

Ipc: C21D 9/46 20060101AFI20220419BHEP

DAV Request for validation of the european patent (deleted)
DAX Request for extension of the european patent (deleted)
STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: EXAMINATION IS IN PROGRESS

17Q First examination report despatched

Effective date: 20241204

GRAP Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOSNIGR1

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: GRANT OF PATENT IS INTENDED

INTG Intention to grant announced

Effective date: 20250610

GRAS Grant fee paid

Free format text: ORIGINAL CODE: EPIDOSNIGR3

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE PATENT HAS BEEN GRANTED

P01 Opt-out of the competence of the unified patent court (upc) registered

Free format text: CASE NUMBER: UPC_APP_0216_3848477/2025

Effective date: 20250711

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

REG Reference to a national code

Ref country code: GB

Ref legal event code: FG4D

REG Reference to a national code

Ref country code: CH

Ref legal event code: EP

REG Reference to a national code

Ref country code: IE

Ref legal event code: FG4D

REG Reference to a national code

Ref country code: DE

Ref legal event code: R096

Ref document number: 602019075896

Country of ref document: DE

REG Reference to a national code

Ref country code: SE

Ref legal event code: TRGR

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 20251128

Year of fee payment: 7

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: NO

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20251217

REG Reference to a national code

Ref country code: LT

Ref legal event code: MG9D

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FI

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20250917

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: HR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20250917

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20251218

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: SE

Payment date: 20251127

Year of fee payment: 7

REG Reference to a national code

Ref country code: NL

Ref legal event code: MP

Effective date: 20250917

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: LV

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20250917

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: BG

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20250917

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: RS

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20251217

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: NL

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20250917

REG Reference to a national code

Ref country code: AT

Ref legal event code: MK05

Ref document number: 1838328

Country of ref document: AT

Kind code of ref document: T

Effective date: 20250917