WO2018008698A1 - 線材、鋼線及び部品 - Google Patents

線材、鋼線及び部品 Download PDF

Info

Publication number
WO2018008698A1
WO2018008698A1 PCT/JP2017/024705 JP2017024705W WO2018008698A1 WO 2018008698 A1 WO2018008698 A1 WO 2018008698A1 JP 2017024705 W JP2017024705 W JP 2017024705W WO 2018008698 A1 WO2018008698 A1 WO 2018008698A1
Authority
WO
WIPO (PCT)
Prior art keywords
bainite
particle size
less
average
wire
Prior art date
Application number
PCT/JP2017/024705
Other languages
English (en)
French (fr)
Japanese (ja)
Inventor
真 小此木
直樹 松井
Original Assignee
新日鐵住金株式会社
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 新日鐵住金株式会社 filed Critical 新日鐵住金株式会社
Priority to MX2018015999A priority Critical patent/MX2018015999A/es
Priority to CN201780037106.0A priority patent/CN109312436B/zh
Priority to KR1020187038029A priority patent/KR102154575B1/ko
Priority to JP2018526423A priority patent/JP6673478B2/ja
Priority to US16/314,122 priority patent/US20200123625A1/en
Publication of WO2018008698A1 publication Critical patent/WO2018008698A1/ja

Links

Images

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
    • 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
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—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
    • C22C38/24—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
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
    • C—CHEMISTRY; METALLURGY
    • 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
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/003—Cementite

Definitions

  • the present invention relates to a wire, a steel wire produced from the wire, and a part having a tensile strength produced from the steel wire of 700 MPa to 1200 MPa.
  • a machine part and a building part are contained in the components used as object in this invention.
  • High-strength mechanical parts having a tensile strength of 700 MPa or more are used for automobiles and various industrial machines for the purpose of reducing weight and size.
  • this type of high-strength mechanical component is sequentially subjected to hot rolling and spheroidizing annealing on a steel material made of alloy steel obtained by adding alloy elements such as Mn, Cr, Mo, and B to carbon steel for mechanical structure. And then softened, and then cold forged or rolled into a predetermined shape, and then subjected to quenching and tempering treatment to impart strength.
  • JP-A-2-166229 discloses that C: 0.03 to 0.20%, Si: 0.10% or less, Mn: 0.7 to 2.5%, one of V, Nb, and Ti, or A steel containing 2 or more types: 0.05 to 0.30%, B: 0.0005 to 0.0050%, a non-made bainite structure cooled at a cooling rate of 5 ° C / sec or more after wire rolling.
  • a method for manufacturing a tempered machine part is disclosed.
  • JP-A-8-41537 discloses C: 0.05 to 0.20%, Si: 0.01 to 1.0%, Mn: 1.0 to 2.0%, S: 0.015. %, Al: 0.01-0.05%, V: 0.05-0.3% steel is heated to a temperature of 900-1150 ° C. and then hot-rolled.
  • Japanese Patent Laid-Open No. 2000-144306 discloses cold forging in which C is 0.40 to 1.0% by mass, the component composition satisfies a specific conditional expression, and the structure is made of pearlite or pseudo-pearlite. Steel for use is disclosed. This steel has a large amount of C and is inferior in cold forgeability as compared with carbon steel for machine structure and alloy steel for machine structure conventionally used for machine parts.
  • the present invention (A) a component having a tensile strength of 700 to 1200 MPa that can be manufactured at low cost; (B) To provide a steel wire capable of omitting the spheroidizing annealing, quenching / tempering treatment, and bluing treatment after cold forging, and a wire rod for producing the steel wire used for the production of the part. , With the goal.
  • the present inventors can perform cold forging even if spheroidizing annealing is omitted, and the tensile strength is 700 MPa or more without performing tempering treatment of quenching and tempering.
  • the relationship between the composition of steel and the structure to obtain high strength parts was investigated.
  • the present invention has been made on the basis of metallurgical findings obtained through such investigations, and the gist thereof is as follows.
  • the above wire material further contains one or two of Cr: 0 to 0.40%, Nb: 0 to 0.03%, and V: 0 to 0.10% by mass%.
  • the above steel wire further comprises one or two of Cr: 0 to 0.40%, Nb: 0 to 0.03%, V: 0 to 0.10% in mass%.
  • the above component further contains one or two of Cr: 0 to 0.40%, Nb: 0 to 0.03%, and V: 0 to 0.10% by mass%.
  • Cr 0 to 0.40%
  • Nb 0 to 0.03%
  • V 0 to 0.10% by mass%.
  • high-strength parts having a tensile strength of 700 to 1200 MPa that contribute to weight reduction and downsizing of machine parts used in automobiles and various industrial machines and construction parts used at construction sites are provided at low cost. can do.
  • the present inventors can perform cold forging even if spheroidizing annealing is omitted, and a tensile strength exceeding 700 MPa without performing tempering treatment of quenching and tempering.
  • the relationship between the composition of steel and the structure for obtaining high strength parts was investigated in detail. And in order to manufacture high-strength parts inexpensively, the present inventors based on the metallurgical knowledge obtained in the investigation, in-line heat treatment using the retained heat at the time of hot rolling of the wire, and the subsequent steel wire A comprehensive study of a series of manufacturing methods up to parts was conducted, and the following conclusions were reached.
  • a steel wire that has been strengthened by wire drawing and cold forging is inferior in workability, has high deformation resistance, and is susceptible to work cracking.
  • the structure is mainly composed of bainite, the block particle size of the surface layer is made fine, and the average particle size of cementite dispersed in bainite is 0. It is effective to set the thickness to 1 ⁇ m or less.
  • Such a steel wire that can be cold forged even if spheroidizing annealing is omitted, and that is a material for obtaining a high-strength part without performing tempering treatment of quenching and tempering, It is effective to have a microstructure with the above characteristics at the stage of steel wire, and to process this into a part without performing heat treatment before processing.
  • the present invention is advantageous.
  • the component of the present invention is a bainite-based material composed of a predetermined average block particle size and cementite particle size by immersing a steel material having an adjusted composition in a molten salt bath using residual heat during hot rolling. It is manufactured by a series of manufacturing methods in which a wire is drawn at a specific temperature at room temperature, a high-strength bainite is adjusted, and molded into a part.
  • parts having a tensile strength of 700 to 1200 MPa can be manufactured at low cost.
  • Component composition Wires for parts having a tensile strength of 700 to 1200 MPa according to the present embodiment, and steel wires (hereinafter sometimes simply referred to as “wires” and “steel wires”, respectively), and parts according to the present embodiment (
  • the composition of the component (sometimes simply referred to as “component”) will be described.
  • the steel wire according to the present embodiment is obtained by drawing the wire according to the present embodiment.
  • the component which concerns on this embodiment is obtained by cold forging the steel wire which concerns on this embodiment, or cold forging and rolling. Wire drawing, cold forging, and rolling do not affect the composition of the steel. Therefore, the description regarding the component composition described below applies to any of wire, steel wire, and parts.
  • “%” means “mass%”.
  • the balance of the component composition is Fe and inevitable impurities.
  • C 0.15-0.30%
  • C is an element necessary for ensuring tensile strength.
  • the C content is less than 0.15%, it is difficult to obtain a tensile strength of 700 MPa or more.
  • the C content is 0.20% or more.
  • the C content exceeds 0.30%, the cold forgeability deteriorates.
  • it is 0.25% or less.
  • Si 0.05 to 0.50%
  • Si is a deoxidizing element and is an element that increases the tensile strength by solid solution strengthening.
  • the Si content is less than 0.05%, the effect of addition is not sufficiently exhibited.
  • the Si content is 0.15% or more.
  • the Si content is more than 0.50%, the effect of addition is saturated, the ductility during hot rolling is deteriorated, and soot is easily generated.
  • a preferable Si content is 0.30% or less.
  • Mn 0.50 to 1.50%
  • Mn is an element that increases the tensile strength of steel.
  • the Mn content is less than 0.50%, the effect of addition is not sufficiently exhibited.
  • the Mn content is 0.70% or more.
  • the Mn content is more than 1.50%, the effect of addition is saturated, and the transformation completion time in the isothermal transformation treatment of the wire becomes long, and the productivity is deteriorated.
  • a preferable Mn content is 1.30% or less.
  • P 0.030% or less
  • P is an element that segregates at a grain boundary and deteriorates cold workability.
  • a preferable P content is 0.015% or less. Since the wire, the steel wire, and the component according to the present embodiment do not need to contain P, the lower limit value of the P content is 0%.
  • S 0.030% or less S, like P, is an element that segregates at the grain boundaries and degrades the cold workability. When the S content exceeds 0.030%, the cold workability is significantly deteriorated.
  • a preferable S content is 0.015% or less, more preferably 0.010% or less. Since the wire, the steel wire, and the fixture which concern on this embodiment do not need to contain S, the lower limit of S content is 0%.
  • Al 0.005 to 0.060%
  • Al is a deoxidizing element and an element that forms AlN that functions as pinning particles. AlN refines crystal grains, thereby improving cold workability.
  • Al is an element having an action of reducing solid solution N and suppressing dynamic strain aging.
  • a preferable Al content is 0.020% or more.
  • the Al content is more than 0.060%, the above effect is saturated and wrinkles are likely to occur during hot rolling.
  • a preferable Al content is 0.050% or less.
  • Ti 0.005 to 0.030%
  • Ti is a deoxidizing element, and is an element that forms TiN and has an action of suppressing solid strain aging by reducing solid solution N.
  • a preferable Ti content is 0.010% or more.
  • the Ti content is more than 0.030%, the above effects are saturated and wrinkles are likely to occur during hot rolling.
  • a preferable Ti content is 0.025% or less.
  • B 0.0003 to 0.0050% B has the effect of suppressing grain boundary ferrite and improving cold workability, and the effect of promoting bainite transformation and improving strength. If it is less than 0.0003%, the effect is insufficient, and if it exceeds 0.0050%, the effect is saturated.
  • N 0.0010 to 0.0100%
  • N is an element that may deteriorate cold workability due to dynamic strain aging. In order to avoid such adverse effects, the N content is set to 0.0100% or less. N also has the effect of increasing the cold workability by forming AlN or TiN to reduce the crystal grain size. For this reason, the lower limit was made 0.0010%. A preferable N content is 0.0020 to 0.0040%.
  • one or two of Cr: 0.01 to 0.40%, Nb: 0 to 0.03%, and V: 0 to 0.10% may be contained.
  • the content of Cr, Nb and V is arbitrary and may be 0%.
  • Cr has the effect of increasing the tensile strength of the steel
  • Nb and V have the effect of reducing the solid solution N to suppress dynamic strain aging, and the effect of increasing the strength by promoting bainite transformation.
  • Cr 0.01-0.40% Cr is an element that increases the tensile strength of steel.
  • the Cr content is less than 0.01%, the above effects cannot be obtained sufficiently.
  • the Cr content is more than 0.40%, martensite is liable to occur, thereby deteriorating the wire drawing workability and the cold forgeability.
  • a preferable content of Cr is 0.03 to 0.30%.
  • Nb 0 to 0.03%
  • Nb is an element which has the effect
  • the Nb content is preferably 0.025% or less.
  • V 0 to 0.10%
  • V is an element that has the function of forming VN, reducing solid solution N, and suppressing dynamic strain aging.
  • V content exceeds 0.10%, the above-described effects are saturated and wrinkles are likely to occur during hot rolling.
  • a preferable V content is 0.05% or less.
  • O 0 to 0.0030% or less O is present as an oxide such as Al and Ti in wire rods, steel wires, and parts (for example, machine parts). When the O content exceeds 0.0030%, coarse oxides are generated in the steel, and fatigue failure is likely to occur.
  • a preferable O content is 0.0020% or less. The lower limit of the O content is 0%.
  • the remainder of a component composition is Fe and an unavoidable impurity.
  • the inevitable impurities are components that are included in raw materials or mixed in during the manufacturing process, and are components that are not intentionally included in steel.
  • Inevitable impurities are specifically Sb, Sn, W, Co, As, Mg, Pb, Bi, and H.
  • Sb, Sn, W, Co, As, Mg, Pb, Bi, and H are 0.010%, 0.10%, 0.50%, 0, respectively, for realizing the effects of the present application. It is acceptable to include up to .50%, 0.010%, 0.010%, 0.10%, 0.10%, and 0.0010%.
  • the steel wire according to the present embodiment is obtained by drawing the wire according to the present embodiment, and the component according to the present embodiment is obtained by cold forging the steel wire according to the present embodiment, or cold forging. And obtained by rolling.
  • the effect of cold forging and rolling on the metal structure of the part is small. This is because the amount of processing that cold forging and rolling exert on parts is small.
  • the metal structures of the wire, the steel wire, and the component according to the present embodiment include bainite having an area ratio of 90% or more. In this embodiment, as shown in FIG.
  • 1, bainite is obtained by etching a cross section (cross section perpendicular to the axis of a steel material (steel wire)) of an object (wire material, steel wire or component) with nital, When a position of a predetermined depth from the surface layer of the object (for example, a depth of 0.25 times the diameter from the surface layer) is photographed with a scanning electron microscope (SEM), acicular or granular cementite is dispersed. It is a recognized organization.
  • SEM scanning electron microscope
  • the bainite area ratio of the wire, steel wire, and parts is determined by the following procedure. That is, first, the cross section of the object is etched with nital to reveal the structure. Next, assuming that the diameter of the object is D, the four positions determined by rotating every 90 ° about the longitudinal axis of the symmetrical object at a depth position of 50 ⁇ m from the surface layer of the object. And four locations determined by rotating the object about 90 ° around the axis at a depth position of 0.25D, and the center part of the axis (the depth from the surface layer is A total of nine locations are identified, including one location determined to a depth position of 0.5D.
  • tissue photographs at a magnification of 1000 times are taken using SEM at these nine locations.
  • the non-bainite (ferrite, pearlite, and martensite structures) in the photographed structure photograph is visually marked, and the area of each structure is obtained by image analysis.
  • the bainite-containing region can be obtained by subtracting the non-bainite region from the entire observation field.
  • the area ratio of this region is defined as the area ratio of bainite.
  • this operation measures and calculates about at least 2 samples, calculates
  • bainite may be difficult to distinguish from the SEM micrograph.
  • KAM method is a pixel of the first approximation that is six adjacent hexagonal pixels in the measurement data, the second approximation that is 12 outside the pixel, or the third approximation that is 18 outside the pixel. This is a method of performing calculation for each pixel by averaging the azimuth differences between them and setting the value as the value of the center pixel. By performing this calculation so as not to cross the grain boundary, a map expressing the orientation change in the grain can be created.
  • the condition for calculating the azimuth difference between adjacent pixels is the third approximation, and the one whose azimuth difference is 5 ° or less is displayed, of which the grains whose azimuth difference exceeds 1 ° are displayed. It shall be bainite.
  • the steel wire may be contained in the steel wire, but as long as the area ratio of bainite in the steel wire is 90% or more, inclusion of a metal structure other than bainite is acceptable. Is done.
  • the area ratio of the bainite of the steel wire is less than 90%, the strength (tensile strength, hardness, etc.) of the steel wire becomes non-uniform, so that cracking is likely to occur during cold working of parts. .
  • the upper limit of the area ratio of the bainite of a steel wire is 100%.
  • the average block particle size of the bainite wire is 15 ⁇ m or less
  • the average block particle size of bainite measured in a cross section is 15 ⁇ m or less.
  • the cross section means a plane perpendicular to the axial direction of the wire.
  • the average aspect ratio R of the bainite block grains measured in the longitudinal section of the steel wire is 1.2 to 2.0 at the surface layer position of the steel wire.
  • the longitudinal section means a plane that is parallel to the axial direction of the wire and includes the central axis.
  • the average aspect ratio R of the bainite block grains of the steel wire and parts is determined as follows. First, a bainite block grain boundary is determined using EBSD with respect to the longitudinal section of a steel wire. At this time, in each of the two regions of 100 ⁇ m in the direction of the steel wire central axis and 500 ⁇ m in the direction of the steel wire central axis from each surface on both sides of the longitudinal section, the measurement step is set to 0.3 ⁇ m at each measurement point in the region. The crystal orientation of bcc-Fe was measured, and a boundary having an orientation difference of 15 degrees or more is defined as a bainite block boundary. And the area
  • a map of bainite block grains is obtained in a total of two regions on both sides of one longitudinal section. This is done on 4 samples to obtain a map of bainite block grains in a total of 8 regions. From the obtained map of bainite block grains, 10 bainite block grains are selected in order from the largest equivalent circle diameter. The aspect ratio of the block grains is measured for the selected 10 bainite block grains, and finally, the average value thereof is calculated as the average aspect ratio R of the bainite block grains.
  • the average block particle size of the surface layer bainite measured in the cross section is (15 / R) ⁇ m or less.
  • the cross section means a plane perpendicular to the axial direction of the steel wire.
  • the average block particle size of bainite in the surface layer of the wire (the same applies to steel wires and parts) is determined as follows. First, in the cross section of the wire, a region extending 500 ⁇ m in the circumferential direction with a width of 500 ⁇ m from the surface layer in the central axis direction is determined, and four regions obtained by rotating this region every 90 ° around the central axis are determined. Identify. And about these four area
  • the average block particle size of the bainite of the part is (15 / R) ⁇ m or less
  • the average block particle size of the surface layer bainite measured in the cross section is (15 / R) ⁇ m or less.
  • the cross section means a plane perpendicular to the axial direction of the component.
  • the ratio of the average block particle size of bainite in the surface layer measured in the cross section and the average block particle size of bainite in the center portion measured in the cross section is 1.0. Is less than. When the ratio exceeds 1.0, the cold forgeability of the steel wire deteriorates and the yield strength ratio of the parts deteriorates.
  • the average block particle size of bainite at the center of the wire is determined as follows. First, an area of 500 ⁇ m ⁇ 500 ⁇ m centering on the central axis is determined in the cross section of the wire, and the block particle diameter is measured with an EBSD apparatus in this area. Next, after the same measurement was performed on three different cross sections, the block particle diameters of the four samples were averaged to obtain the average block particle diameter of bainite at the center of the wire (the same applies to steel wires and parts).
  • the ratio between the block particle size of the surface layer and the block particle size of the central portion is obtained by (average block particle size of bainite in the surface layer) / (average block particle size of bainite in the central portion).
  • the average particle size of cementite dispersed in bainite is 0.1 ⁇ m or less.
  • the average particle diameter of cementite exceeds 0.1 ⁇ m, the cold forgeability of the steel wire deteriorates. Further, the yield strength ratio of the parts is lowered, and for example, the permanent elongation when used as a machine part is deteriorated.
  • the average particle size of cementite in bainite is determined by the following procedure. First, the cross-section of the object (wire, steel wire or part) is etched using picral to reveal the structure. Next, assuming that the diameter of the object is D, the four positions determined by rotating every 90 ° about the longitudinal axis of the symmetrical object at a depth position of 50 ⁇ m from the surface layer of the object. And four locations determined by rotating the object about 90 ° around the axis at a depth position of 0.25D, and the center part of the axis (the depth from the surface layer is A total of nine locations are identified, including one location determined to a depth position of 0.5D.
  • tissue photographs at a magnification of 20000 times are taken at these nine locations using a field emission scanning electron microscope (FE-SEM).
  • FE-SEM field emission scanning electron microscope
  • the limit compression rate of steel wire is 80% or more
  • the steel wire obtained as described above exhibits good cold workability.
  • the critical compression ratio is used as an index indicating the cold workability.
  • the critical compression ratio is a sample whose height is 1.5 times the diameter from a steel wire after wire drawing by machining, and concentric grooves are formed on the end surface of this sample. When compressing in the axial direction using the attached mold, it means the maximum compression ratio at which no cracks occur.
  • the compression ratio is ((H ⁇ H1) /) where H is the height before drawing (axial dimension) before drawing, and H1 is the height after drawing (axial dimension) after drawing. H) A value indicated by x100.
  • the critical compression ratio can be 80% or more, and excellent cold workability can be realized.
  • the component composition is mass%, C: 0.15 to 0.30%, Si: 0.05 to 0.50%, Mn: 0.50 to 1.50%, P: 0.030% or less S: 0.030% or less, Al: 0.005-0.060%, Ti: 0.005-0.030%, B: 0.0003-0.0050%, N: 0.001-0. 010%, optionally containing one or two of Cr: 0 to 0.40%, Nb: 0 to 0.03%, V: 0 to 0.10%, the balance
  • a steel slab comprising Fe and impurities is prepared. The steel slab is heated to 1000 to 1150 ° C.
  • the wire at 800 to 950 ° C. is cooled to 600 ° C. at an average cooling rate of 40 ° C./s or higher, and then cooled to 480 ° C. at an average cooling rate of 25 ° C./s or higher. Thereafter, the wire is held at a temperature range of 400 to 480 ° C. for 15 seconds or more (first constant temperature hold), and further immersed in a temperature range of 530 to 600 ° C. for 25 seconds or more to hold a constant temperature (second constant temperature). Hold). Finally, the wire is cooled with water.
  • the two-stage cooling after the finish rolling and the first constant temperature holding are performed by immersing the wire in a molten salt at 400 to 480 ° C. in the first molten salt bath.
  • the second constant temperature holding is performed by immersing the wire in a molten salt at 530 to 600 ° C. in the second molten salt bath.
  • the cooling of the wire at 800 to 950 ° C. is performed in two stages of cooling to 600 ° C. and cooling to 600 ° C. to 480 ° C. .
  • the average block particle size of bainite can be controlled to 15 ⁇ m or less by setting the cooling rate to 25 ° C./s or more.
  • the molten salt bath temperature in the first molten salt bath is set to 400 to 480 ° C.
  • the immersion time is set to 15 to 50 s.
  • the molten salt bath temperature in the second molten salt bath can be set to 530 to 600 ° C.
  • the immersion time can be set to 25 to 80 s.
  • the steel wire according to the present embodiment can be manufactured by the following method as an example. That is, the wire manufactured by the above method is drawn at a total area reduction of 10 to 55%.
  • the total area reduction ratio of 10 to 55% in the wire drawing process may be achieved by a single wire drawing process or may be achieved by a plurality of wire drawing processes.
  • the steel wire according to the present embodiment is obtained.
  • the parts (machine parts, building parts, etc.) of this embodiment can be manufactured by the following method as an example. That is, the above steel wire is processed into various parts by cold forging or by cold forging and rolling to obtain a part having a tensile strength of 700 to 1200 MPa.
  • the conditions in the examples are one example of conditions used for confirming the feasibility and effects of the present invention, and the present invention is based on this one example of conditions. It is not limited.
  • the present invention can adopt various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.
  • a tensile test piece is taken from the shaft portion of each part, a tensile test is performed, and the tensile strength and the 0.2% proof stress are measured, and then the proof stress ratio (0.2% proof stress / tensile strength) is 0. .90 parts or more were judged to have good yield strength ratio.
  • levels 1 to 7 and levels 14 to 20 are invention examples, and levels 8 to 13 and levels 21 to 28 are comparative examples.
  • level 10 is an example of manufacturing by immersing in a boiling water tank without performing isothermal transformation after hot rolling.
  • Level 11 is an example of manufacturing by cooling with air cooling without performing a constant temperature transformation treatment after hot rolling.
  • Level 13 is an example in which the hot-rolled wire was once cooled to room temperature, reheated to 1000 ° C., and immersed in one tank of molten salt.
  • Table 3 shows the results relating to the structure of the wire
  • Table 4 shows the results relating to the structure of the steel wire
  • Table 5 shows the results relating to the cold forgeability of the steel wire and the characteristics of the parts.
  • a part having a tensile strength of 700 to 1200 MPa that can be manufactured at low cost can be obtained, and spheroidizing annealing, quenching and tempering used for manufacturing the part can be obtained.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)
  • Heat Treatment Of Strip Materials And Filament Materials (AREA)
PCT/JP2017/024705 2016-07-05 2017-07-05 線材、鋼線及び部品 WO2018008698A1 (ja)

Priority Applications (5)

Application Number Priority Date Filing Date Title
MX2018015999A MX2018015999A (es) 2016-07-05 2017-07-05 Varilla de alambre de acero, alambre de acero, y parte.
CN201780037106.0A CN109312436B (zh) 2016-07-05 2017-07-05 线材、钢线及部件
KR1020187038029A KR102154575B1 (ko) 2016-07-05 2017-07-05 선재, 강선 및 부품
JP2018526423A JP6673478B2 (ja) 2016-07-05 2017-07-05 線材、鋼線及び部品
US16/314,122 US20200123625A1 (en) 2016-07-05 2017-07-05 Steel wire rod, steel wire, and part

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2016-133361 2016-07-05
JP2016133361 2016-07-05

Publications (1)

Publication Number Publication Date
WO2018008698A1 true WO2018008698A1 (ja) 2018-01-11

Family

ID=60912855

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2017/024705 WO2018008698A1 (ja) 2016-07-05 2017-07-05 線材、鋼線及び部品

Country Status (7)

Country Link
US (1) US20200123625A1 (es)
JP (1) JP6673478B2 (es)
KR (1) KR102154575B1 (es)
CN (1) CN109312436B (es)
MX (1) MX2018015999A (es)
TW (1) TWI643959B (es)
WO (1) WO2018008698A1 (es)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111690801B (zh) * 2020-05-25 2021-11-02 中天钢铁集团有限公司 一种获得全贝氏体组织的合金工具钢盘条生产工艺
CN113416884A (zh) * 2021-06-07 2021-09-21 宁夏建龙龙祥钢铁有限公司 一种高延耐蚀钢筋生产方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02166229A (ja) * 1988-12-20 1990-06-26 Toa Steel Co Ltd 非調質ボルト用鋼線材の製造方法
JP2001089830A (ja) * 1999-09-17 2001-04-03 Kobe Steel Ltd 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
WO2012161322A1 (ja) * 2011-05-26 2012-11-29 新日鐵住金株式会社 機械構造用鋼部品およびその製造方法
WO2013031640A1 (ja) * 2011-08-26 2013-03-07 新日鐵住金株式会社 非調質機械部品用線材、非調質機械部品用鋼線、及び、非調質機械部品とそれらの製造方法
WO2015133614A1 (ja) * 2014-03-06 2015-09-11 新日鐵住金株式会社 伸線加工性に優れた高炭素鋼線材とその製造方法

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4349732B2 (ja) * 2000-09-20 2009-10-21 Ｊｆｅ条鋼株式会社 溶接性および加工性に優れたばね用線材および鋼線
JP5092554B2 (ja) * 2007-01-17 2012-12-05 Ｊｆｅスチール株式会社 高強度鉄筋用鋼材の製造方法
CN105612269B (zh) * 2013-10-08 2017-11-14 新日铁住金株式会社 线材、过共析贝氏体钢丝及它们的制造方法
CN104018076B (zh) * 2014-06-25 2016-06-15 武汉钢铁(集团)公司 一种耐高温钢筋及生产方法

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02166229A (ja) * 1988-12-20 1990-06-26 Toa Steel Co Ltd 非調質ボルト用鋼線材の製造方法
JP2001089830A (ja) * 1999-09-17 2001-04-03 Kobe Steel Ltd 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
WO2012161322A1 (ja) * 2011-05-26 2012-11-29 新日鐵住金株式会社 機械構造用鋼部品およびその製造方法
WO2013031640A1 (ja) * 2011-08-26 2013-03-07 新日鐵住金株式会社 非調質機械部品用線材、非調質機械部品用鋼線、及び、非調質機械部品とそれらの製造方法
WO2015133614A1 (ja) * 2014-03-06 2015-09-11 新日鐵住金株式会社 伸線加工性に優れた高炭素鋼線材とその製造方法

Also Published As

Publication number Publication date
CN109312436A (zh) 2019-02-05
JP6673478B2 (ja) 2020-03-25
KR20190012226A (ko) 2019-02-08
TWI643959B (zh) 2018-12-11
TW201812027A (zh) 2018-04-01
US20200123625A1 (en) 2020-04-23
CN109312436B (zh) 2021-08-10
MX2018015999A (es) 2019-05-13
JPWO2018008698A1 (ja) 2019-04-18
KR102154575B1 (ko) 2020-09-10

Similar Documents

Publication Publication Date Title
JP5590246B2 (ja) 非調質機械部品用線材、非調質機械部品用鋼線、及び、非調質機械部品とそれらの製造方法
JP6528860B2 (ja) 非調質機械部品用鋼線及び非調質機械部品
WO2012023483A1 (ja) 特殊鋼鋼線及び特殊鋼線材
JP5776623B2 (ja) 冷間加工性に優れた鋼線材・棒鋼とその製造方法
WO2013094475A1 (ja) 冷間加工用機械構造用鋼およびその製造方法
JP5407178B2 (ja) 冷間加工性に優れた冷間鍛造用鋼線材およびその製造方法
JP4632931B2 (ja) 冷間加工性に優れる高周波焼入れ用鋼及びその製造方法
WO2014199919A1 (ja) 引張強さが９５０～１６００ＭＰａであるパーライト組織ボルト用の鋼線の製造用の線材、引張強さが９５０～１６００ＭＰａであるパーライト組織ボルト用の鋼線、パーライト組織ボルト、及び、それらの製造方法
WO2015194411A1 (ja) 冷間加工用機械構造用鋼及びその製造方法
CN108368583B (zh) 非调质机械部件用钢丝及非调质机械部件
JP5704716B2 (ja) 冷間加工用機械構造用鋼およびその製造方法
JP7151885B2 (ja) 鋼線
WO2018008698A1 (ja) 線材、鋼線及び部品
WO2017033773A1 (ja) 冷間加工用機械構造用鋼、およびその製造方法
WO2017038436A1 (ja) 機械構造部品用鋼線
JP7469643B2 (ja) 鋼線、非調質機械部品用線材、及び非調質機械部品
JP2018044235A (ja) 機械構造部品用鋼線

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 17824301

Country of ref document: EP

Kind code of ref document: A1

ENP Entry into the national phase

Ref document number: 2018526423

Country of ref document: JP

Kind code of ref document: A

ENP Entry into the national phase

Ref document number: 20187038029

Country of ref document: KR

Kind code of ref document: A

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 17824301

Country of ref document: EP

Kind code of ref document: A1