EP3260566B1 - Hot-rolled steel sheet - Google Patents

Hot-rolled steel sheet Download PDF

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Publication number
EP3260566B1
EP3260566B1 EP15882647.9A EP15882647A EP3260566B1 EP 3260566 B1 EP3260566 B1 EP 3260566B1 EP 15882647 A EP15882647 A EP 15882647A EP 3260566 B1 EP3260566 B1 EP 3260566B1
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range
steel sheet
hot
equal
rolled steel
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German (de)
English (en)
French (fr)
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EP3260566A4 (en
EP3260566A1 (en
Inventor
Natsuko Sugiura
Mitsuru Yoshida
Hiroshi Shuto
Tatsuo Yokoi
Masayuki Wakita
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Nippon Steel Corp
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Nippon Steel Corp
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    • 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
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/001—Heat treatment of ferrous alloys containing Ni
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/002—Heat treatment of ferrous alloys containing Cr
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/008—Heat treatment of ferrous alloys containing Si
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—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
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/002—Bainite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/008—Martensite

Definitions

  • the present invention relates to a hot-rolled steel sheet excellent in workability and particularly relates to a hot-rolled steel sheet having a composite structure and excellent in stretch flangeability.
  • the steel sheets used for the structural member, the suspension member, and the like which account for about 20% of the vehicle body weight are press-formed mainly based on stretch flange processing and burring processing after performing blanking and drilling by shearing or punching. For this reason, excellent stretch flangeability is required for such steel sheets.
  • Patent Document 1 discloses a hot-rolled steel sheet in which the fraction and the size of the martensite, the number density, and the average gap between martensite is specified, and is excellent in elongation and hole expansibility.
  • Patent Document 2 discloses a hot-rolled steel sheet in which average particle diameters of ferrite and a second phase and a carbon concentration of the second phase are limited, and is excellent in burring workability.
  • Patent Document 3 discloses a hot-rolled steel sheet which is obtained by coiling the steel sheet at a low temperature after being kept at a temperature in a range of 750°C to 600°C for 2 to 15 seconds, and is excellent in workability, surface texture, and plate flatness.
  • Patent Document 1 since a primary cooling rate should be set to be equal to or higher than 50°C/s after completing the hot rolling, the load applied on an apparatus becomes higher. In addition, in a case of setting the primary cooling rate to be equal to or higher than 50°C/s, there is a problem in that unevenness in material properties is caused by unevenness in the cooling rate.
  • breaking occurs without the strains in the circumferential direction are hardly distributed; however, in the actual process of components, strain distribution is present, and thus a gradient of the strain and the stress in the vicinity of the broken portion affects a breaking limit. Accordingly, regarding the high-strength steel sheet, even if the stretch flangeability is sufficient in the hole expansion test, in a case of performing cold pressing, the breaking may occur due to the strain distribution.
  • Patent Documents 1 to 3 disclose that in all of the inventions, the hole expansibility is improved by specifying only the structures observed using an optical microscope. However, it is not clear whether or not sufficient stretch flangeability can be secured even in consideration of the strain distribution.
  • Patent Document 4 discloses a method for manufacturing steel sheets which have excellent workability including the stretch flanging performance and which have various strength levels with homogeneous mechanical properties.
  • the present invention has been made in consideration of the above-described circumstance.
  • An object of the present invention is to provide a high-strength hot-rolled steel sheet which is excellent in the stretch flangeability and can be applied to a member which requires high strength and the strict stretch flangeability.
  • the stretch flangeability means a value evaluated by a product of limit forming height H (mm) and tensile strength TS (MPa) of the flange obtained as a result of the test by the saddle type stretch flange test method, which is an index of the stretch flangeability in consideration of the strain distribution.
  • the excellent stretch flangeability means that the product of the limit forming height H (mm) and the tensile strength TS (MPa) is equal to or greater than 19500 (mm.MPa).
  • the high strength means that the tensile strength is equal to or greater than 590 MPa. There is no need to particularly set the upper limit of the strength; however, in the range of the structure defined in the present invention, it is difficult to secure a strength of greater than 1470 MPa.
  • the improvement of the stretch flangeability has been performed by inclusion control, homogenization of structure, unification of structure, and/or reduction in hardness difference between structure, as disclosed in Patent Documents 1 to 3.
  • hole expansibility, workability, or the like have been improved by controlling the structure which can be observed using an optical microscope.
  • the present inventors made an intensive study by focusing an intragranular orientation difference in grains in consideration that the stretch flangeability under the presence of the strain distribution cannot be improved even by controlling only the structure observed using an optical microscope. As a result, it was found that it is possible to greatly improve the stretch flangeability by controlling the ratio of the grains in which the intragranular orientation difference is in a range of 5° to 14° with respect to the entire grains to be within a certain range.
  • the present invention is configured on the basis of the above findings, and the gists thereof are as follows.
  • a hot-rolled steel sheet (hereinafter, referred to as a hot-rolled steel sheet according to the present embodiment in some case) of the embodiment of the present invention will be described in detail.
  • the hot-rolled steel sheet according to the present embodiment includes, as a chemical composition, by mass%, C: 0.04% to 0.18%, Si: 0.10% to 1.70%, Mn: 0.50% to 3.00%, Al: 0.010% to 1.00%, and optionally B: 0.005% or less, Cr: 1.0% or less, Mo: 1.0% or less, Cu: 2.0% or less, Ni: 2.0% or less, Mg: 0.05% or less, REM: 0.05% or less, Ca: 0.05% or less, Zr: 0.05% or less, P: limited to equal to or less than 0.050%, S: limited to equal to or less than 0.010%, and N: limited to equal to or less than 0.0060%, with the remainder including Fe and impurities.
  • a structure in the hot-rolled steel sheet according to the present embodiment, includes, by area ratio, ferrite and bainite in a range of 75% to 95% in total, and martensite in a range of 5% to 20%.
  • a boundary having an orientation difference of equal to or greater than 15° is defined as a grain boundary
  • an area which is surrounded by the grain boundary and has an equivalent circle diameter of equal to or greater than 0.3 ⁇ m is defined as a grain
  • the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° is, by area ratio, in a range of 10% to 60%.
  • the amount (%) of the respective elements is based on mass%.
  • the C is an element which contributes to improvement of the strength of steel.
  • the lower limit of the C content is set to 0.04%.
  • the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° is decreased. From this point, the lower limit of the C content is set to 0.04%.
  • the lower limit of the C content is preferably 0.045%, and the lower limit of the C content is further preferably 0.05%.
  • the C content is greater than 0.18%, the stretch flangeability and the weldability are deteriorated.
  • the hardenability is excessively enhanced, and the grains having an intragranular orientation difference of greater than 14° are increased, thereby the ratio of grains having an intragranular orientation difference in a range of 5° to 14° is decreased.
  • the upper limit of the C content is set to 0.18%.
  • the upper limit of the C content is preferably 0.17%, and the upper limit of the C content is further preferably 0.16%.
  • the lower limit of the Si content is set to 0.10%.
  • the lower limit of the Si content is preferably 0.12%, the lower limit of the Si content is further preferably 0.15%.
  • the upper limit of the Si content is set to 1.70%.
  • the upper limit of the Si content is preferably 1.60%, and the upper limit of the Si content is further preferably 1.50%.
  • the lower limit of the Mn content is set to 0.50%.
  • the lower limit of the Mn content is preferably 0.65%, and the lower limit of the Mn content is further preferably 0.70%.
  • the upper limit of the Mn content is set 3.00%.
  • the upper limit of the Mn content is preferably 2.60%, and is further preferably the upper limit of the Mn content is 2.30%.
  • the lower limit of the Al content is set to 0.010%.
  • the lower limit of the Al content is preferably 0.015%, and the lower limit of the Al content is further preferably 0.020%.
  • the Al content is greater than 1.00%, the weldability and the toughness are deteriorated.
  • the upper limit of the Al content is set to 1.00%.
  • the upper limit of the Al content is preferably 0.90%, and the upper limit of the Al content is further preferably 0.80%.
  • P is an impurity.
  • P causes the toughness, the workability, and the weldability to be deteriorated, and thus the less the content, the better.
  • the P content is greater than 0.050%, the stretch flangeability is remarkably deteriorated, and thus the P content is limited to be equal to or less than 0.050%.
  • the P content is further preferably equal to or less than 0.040%.
  • S is an element for forming an A type inclusion which not only causes cracks at the time of hot rolling, but also makes the stretch flangeability deteriorated. For this reason, the less the S content, the better.
  • the S content is further preferably equal to or less than 0.005%.
  • N is an element which forms AlN during the cooling after hot rolling, and deteriorates the formability of the steel sheet.
  • the upper limit of the N content is limited to be equal to or less than 0.0060%.
  • the upper limit of the N content is preferably 0.0040%.
  • the above-described chemical elements are base elements contained in the hot-rolled steel sheet according to the present embodiment, and a chemical composition which contains such basic elements, with the remainder including Fe and impurities is a base composition of the hot-rolled steel sheet according to the present embodiment.
  • the impurities are elements contaminated in the steel, which are caused from raw materials such as ore and scrap at the time of industrially manufacturing an alloy such as As and Sn, or caused by various factors in the manufacturing process, and are in an allowable range which does not adversely affect the properties of the hot-rolled steel sheet according to the present embodiment.
  • the hot-rolled steel sheet further contains, if necessary, one or more of B, Cr, Mo, Cu, Ni, Mg, REM, Ca, and Zr within a range described below. It is not necessary to contain these elements, and thus the lower limit of the content is 0%.
  • Nb and Ti limit the recrystallization and thus the workability is deteriorated. For this reason, Nb is preferably less than 0.005%, and Ti is preferably less than 0.015.
  • the B is an element which improves the hardenability, and contributes to strengthening of steel.
  • the B content is preferably set to be equal to or greater than 0.0001%.
  • the B content is greater than 0.0050%, the workability is deteriorated.
  • bainite having a large orientation dispersion is likely to be generated at the time of quenching, and the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° is decreased. For this reason, even in a case of containing B, the upper limit of the B content is preferably 0.0050%.
  • Cr is an element which contributes to improvement of the strength of steel.
  • Cr is an element having an effect of limiting cementite.
  • the Cr content is preferably equal to or greater than 0.01%.
  • the upper limit of the Cr content is preferably 1.0%.
  • Mo is an element which improves the hardenability and has an effect of enhancing the strength by forming a carbide.
  • the Mo content is preferably equal to or greater than 0.01%.
  • the Mo content is set to 1.0% even in a case of containing Mo.
  • the Cu is an element which enhances the strength of steel sheet and improves corrosion resistance and the exfoliation properties of the scale.
  • the Cu content is preferably equal to or greater than 0.01%, and is further preferably equal to or greater than 0.04%.
  • the upper limit of the Cu content is preferably set to 2.0%, and is further preferably set to 1.0%.
  • Ni is an element which enhances the strength and improves the toughness of the steel sheet.
  • the Ni content is preferably equal to or greater than 0.01%.
  • the upper limit of the Ni content is preferably set to 2.0%.
  • All of Ca, Mg, Zr, and REM are elements which improve the toughness by controlling the shape of sulfides and oxides. Accordingly, in order to obtain such effects, each of one or more of these elements is preferably equal to or greater than 0.0001%, and is further preferably equal to or greater than 0.0005%. However, when the amount of these elements is excessively high, the stretch flangeability is deteriorated. For this reason, even in the case of containing these elements, the upper limit of each content is preferably set to 0.05%.
  • the hot-rolled steel sheet according to the present embodiment contain, by area ratio, ferrite and bainite in a range of 75% to 95% in total, and martensite in a range of 5% to 20%, in the structure observed using an optical microscope.
  • ferrite and bainite in a range of 75% to 95% in total
  • martensite in a range of 5% to 20%
  • the hot-rolled steel sheet according to the present embodiment contains, by area ratio, ferrite and bainite in a range of 75% to 95% in total, and martensite in a range of 5% to 20%, in the structure observed using an optical microscope.
  • the total amount of the ferrite and the bainite is less than 75% by area ratio, the stretch flangeability is deteriorated.
  • the total area ratio of the ferrite and the bainite is greater than 95%, the strength is deteriorated, the ductility is deteriorated, and thereby it is difficult to secure the properties which are generally required for the vehicle members.
  • each of the fraction (the area ratio) of the ferrite and the bainite is not necessarily limited, when the fraction of the ferrite is greater than 90%, sufficient strength cannot be obtained in some cases, and thus the fraction of the ferrite is preferably equal to less than 90%, and is further preferably less than 70%.
  • the fraction of the bainite is greater than 60%, the ductility may be deteriorated, and thus the fraction of the bainite is preferably less than 60%, and is further preferably less than 50%.
  • the structures of the remainders other than the ferrite, bainite, and martensite are not particularly limited, and for example, it may be residual austenite, pearlite, or the like.
  • the ratio of the structures of the remainders is preferably equal to or less than 5%, further preferably equal to or less than 3%, and still further preferably 0%, by area ratio.
  • the structure fraction (the area ratio) can be obtained using the following method. First, a sample collected from the hot-rolled steel sheet is etched using nital. After etching, a structure photograph obtained at a 1/4 thickness position in a visual field of 300 ⁇ m ⁇ 300 ⁇ m using an optical microscope is subjected to image analysis, and thereby the area ratio of ferrite and pearlite, and the total area ratio bainite and martensite are obtained. Then, a sample etched by LePera solution, the structure photograph obtained at a 1/4 thickness position in the visual field of 300 ⁇ m ⁇ 300 ⁇ m using the optical microscope is subjected to the image analysis, and thereby the total area ratio of residual austenite and martensite is calculated.
  • the volume fraction of the residual austenite is obtained through X-ray diffraction measurement.
  • the volume fraction of the residual austenite is equivalent to the area ratio, and thus is set as the area ratio of the residual austenite.
  • the hot-rolled steel sheet according to the present embodiment it is necessary to control the structure observed using the optical microscope to be within the above-described range, and to control the ratio of the grains having an intragranular orientation difference in a range of 5° to 14°, obtained using an EBSD method (electron beam back scattering diffraction pattern analysis method) frequently used for the crystal orientation analysis.
  • EBSD method electron beam back scattering diffraction pattern analysis method
  • the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° is set to be in a range of 10% to 60% by area ratio, with respect to the entire grains.
  • the grains having such intragranular orientation difference are effective to obtain the steel sheet which has the strength and the workability in the excellent balance, and thus when the ratio is controlled, it is possible to greatly improve the stretch flangeability while maintaining a desired steel sheet strength.
  • the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° is less than 10% by area ratio, the stretch flangeability is deteriorated.
  • the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° is greater than 60% by area ratio, the ductility is deteriorated.
  • an intragranular orientation difference is related to a dislocation density contained in the grains.
  • the increase in the intragranular dislocation density causes the workability to be deteriorated while bringing about the improvement of the strength.
  • the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° is controlled to be in a range of 10% to 60%.
  • the grains having an intragranular orientation difference of less lower 5° are excellent in the workability, but are hard to be highly strengthened, and the grains having an intragranular orientation difference of greater than 14° have different deformations therein, and thus do not contribute to the improvement of the stretch flangeability.
  • the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° can be measured by the following method.
  • an area of 200 ⁇ m in the rolling direction, and 100 ⁇ m in the normal direction to the rolled surface is subjected to EBSD analysis at a measurement pitch of 0.2 ⁇ m so as to obtain crystal orientation information.
  • the EBSD analysis is performed using an apparatus which is configured to include a thermal field emission scanning electron microscope (JSM-7001F, manufactured by JEOL) and an EBSD detector (HIKARI detector manufactured by TSL), at an analysis speed in a range of 200 to 300 points per second.
  • an area having the orientation difference of equal to or greater than 15° and an equivalent circle diameter of equal to or greater than 0.3 ⁇ m is defined as a grain, the average intragranular orientation difference of the grains is calculated, and the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° is obtained.
  • the grain defined as described above and the average intragranular orientation difference can be calculated using software "OIM Analysis (trademark)" attached to an EBSD analyzer.
  • the "intragranular orientation difference” of the present invention means "Grain Orientation Spread (GOS)" which is an orientation dispersion in the grains, and the value thereof is obtained as an average value of reference crystal orientations and misorientations of all of the measurement points within the same grain as disclosed in " Misorientation Analysis of Plastic Deformation of Stainless Steel by EBSD and X-Ray Diffraction Methods", KIMURA Hidehiko, journal of the Japan Society of Mechanical Engineers (Series A) Vol.71, No.712, 2005, p. 1722 to 1728 .
  • the reference crystal orientation is an orientation obtained by averaging all of the measurement points in the same grain, a value of GOS can be calculated using "OIM Analysis (trademark) Version 7.0.1" which is software attached to the EBSD analyzer.
  • FIG. 1 is an example of an EBSD analysis result of an area of 100 ⁇ m ⁇ 100 ⁇ m at 1/4t portion in the cross section vertical to the rolling direction of the hot-rolled steel sheet according to the present embodiment.
  • an area shown in black indicates martensite.
  • the stretch flangeability is evaluated using the saddle type stretch flange test method in which the saddle-shaped formed product is used. Specifically, the saddle-shaped formed product simulating the stretch flange shape formed of a linear portion and an arc portion as illustrated in FIG. 2 is pressed, and the stretch flangeability is evaluated using a limit forming height at this time.
  • the limit forming height H (mm) when a clearance at the time of punching a corner portion is set to 11% is measured using the saddle-type formed product in which a radius of curvature R of a corner is set to be in a range of 50 to 60 mm, and an opening angle ⁇ is set to 120°.
  • the clearance indicates the ratio of a gap between a punching die and a punch, and the thickness of the test piece.
  • the clearance is determined by combination of a punching tool and the sheet thickness, and thus the value of 11 % means a range of 10.5% to 11.5%.
  • the existence of the cracks having a length of 1/3 of the sheet thickness are visually observed after forming, and then a forming height of the limit in which the cracks are not present is determined as the limit forming height.
  • the area ratio of each of the structures of the ferrite and bainite which are observed using the optical microscope is not directly related to the ratio of the grains having an intragranular orientation difference in a range of 5° to 14°.
  • the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° are not necessarily the same. Accordingly, it is not possible to obtain the properties corresponding to the hot-rolled steel sheet according to the present embodiment only by controlling the ferrite area ratio, the bainite area ratio, and the martensite area ratio. Details for this will be described in Examples below.
  • the hot-rolled steel sheet according to the present embodiment can be obtained using a manufacturing method including a hot rolling process and a cooling process as follows.
  • the hot-rolled steel sheet is obtained by heating and hot rolling a slab having the above-described chemical composition.
  • the slab heating temperature is preferably in a range of 1050°C to 1260°C.
  • the slab heating temperature is lower than 1050°C, it is difficult to secure the hot rolling finishing temperature, which is not preferable.
  • the slab heating temperature is equal to or higher than 1260°C, the yield is decreased due to the scale off, and thus the heating temperature is preferably equal to or lower than 1260°C.
  • the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° is set to be in a range of 10% to 60% by area ratio, in the hot rolling performed on the heated slab, it is important to set cumulative strains in a latter three stages (last three passes) of finish rolling to be greater than 0.6 to 0.7, and then perform cooling described below.
  • the reason for this is that since the grain having an intragranular orientation difference in a range of 5° to 14° is generated by being transformed at a relatively low temperature in a para-equilibrium state, it is possible to control the generation of grain having an intragranular orientation difference in a range of 5° to 14° by limiting the dislocation density of austenite before the transformation to be in a certain range and limiting the cooling rate after transformation to be in a certain range.
  • the cumulative strain at the latter three stages in the finish rolling, and the subsequent cooling are controlled, the grain nucleation frequency of the grain having an intragranular orientation difference in a range of 5° to 14°, and the subsequent growth rate can be controlled, and thus it is possible to control the area ratio which is obtained as a result.
  • the dislocation density of the austenite introduced through the finish rolling is mainly related to the grain nucleation frequency
  • the cooling rate after rolling is mainly related to the growth rate.
  • the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° is less than 10%, which is not preferable.
  • the cumulative strain at the latter three stages in the finish rolling is greater than 0.7, the recrystallization of the austenite occurs during the hot rolling, the accumulated dislocation density at the time of the transformation is decreased, and thus the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° is less than 10%, which is not preferable.
  • the cumulative strain ( ⁇ eff.) at the latter three stages in the finish rolling in the present embodiment can be obtained from the following Equation (1).
  • ⁇ ⁇ eff . ⁇ ⁇ i t T
  • ⁇ ⁇ i t T ⁇ ⁇ i 0 / exp t / ⁇ R 2 / 3
  • ⁇ ⁇ R ⁇ 0 ⁇ exp Q / RT
  • ⁇ 0 8.46 ⁇ 10 ⁇ 6
  • Q 183200 J
  • R 8.314 J / K ⁇ mol
  • ⁇ i0 represents a logarithmic strain at the time of rolling reduction
  • t represents a cumulative time immediately before the cooling in the pass
  • T represents a rolling temperature in the pass.
  • the rolling finishing temperature of the hot rolling is preferably in a range of Ar3°C to Ar3 + 60°C.
  • the rolling finishing temperature is higher than Ar3 + 60°C, the grain size of the hot-rolled sheet becomes larger, thus the workability is deteriorated, and the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° is decreased, which is not preferable.
  • the rolling finishing temperature is lower than Ar3, the hot rolling is performed in the two phase region, thus the ferrite phase is deformed, the ductility and the hole expansibility of the hot-rolled steel sheet are deteriorated, and the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° is decreased, which is not preferable.
  • the hot rolling includes rough rolling and finish rolling
  • the finish rolling is preferably performed using a tandem mill with which a plurality of mills are linearly arranged and continuously rolling in one direction so as to obtain a desired thickness.
  • cooling cooling between stands
  • the maximum temperature of the steel sheet during the finish rolling is controlled to be in a range of Ar3 + 60°C to Ar3 + 150°C.
  • the range of the dislocation density of austenite before the transformation can be limited, and as a result, it is possible to obtain a desired ratio of the grains having an intragranular orientation difference in a range of 5° to 14°.
  • Ar3 can be calculated by the following Expression (2) in consideration of the influence on the transformation point by rolling reduction.
  • Ar 3 970 ⁇ 325 ⁇ C + 33 ⁇ Si ⁇ 287 ⁇ P + 40 ⁇ Al ⁇ 92 ⁇ Mn + Mo + Cu ⁇ 46 ⁇ Cr + Ni
  • [C], [Si], [P], [Al], [Mn], [Mo], [Cu], [Cr], and [Ni] each represent, by mass%, the amount of each of C, Si, P, Al, Mn, Mo, Cu, Cr, and Ni.
  • the elements which are not contained are calculated as 0%.
  • the hot-rolled steel sheet which was subjected to the hot rolling controlled as described above is cooled.
  • the hot-rolled steel sheet after completing the hot rolling is cooled (first cooling) down to a temperature range in a range of 650°C to 750°C at a cooling rate of equal to or greater than 10°C/s, and the temperature is kept for 3 to 10 seconds in the temperature range, and thereafter, the hot-rolled steel sheet is cooled (second cooling) down to the temperature of equal to or lower than 100°C at a cooling rate of equal to or greater than 30°C/s.
  • the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° is less than 10%, which is not preferable.
  • a cooling stopping temperature in the first cooling is lower than 650°C, the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° is less than 10%, which is not preferable.
  • the cooling stopping temperature in the first cooling is higher than 750°C
  • the martensite fraction is excessively low, the strength is decreased, and the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° is greater than 60%, which is not preferable.
  • the retention time is shorter than three seconds at a temperature range of 650°C to 750°C
  • the martensite fraction is excessively high, the ductility is deteriorated, and the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° is less than 10%, which is not preferable.
  • the martensite fraction When the retention time at a temperature range of 650°C to 750°C is longer than 10 seconds, the martensite fraction is decreased, the strength is deteriorated, and the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° is less than 10%, which is not preferable.
  • the cooling rate of the second cooling is lower than 30°C/s, the martensite fraction is decreased, the strength is deteriorated, and the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° is greater than 60%, which is not preferable.
  • the cooling stopping temperature of the second cooling is higher than 100°C, the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° is greater than 60%, which is not preferable.
  • the cooling rate in the first cooling and the second cooling may be set to be equal to or lower than 200°C/s in consideration of the equipment capacity of the cooling facility.
  • the above-described manufacturing method it is possible to obtain a structure which has, by area ratio, ferrite and bainite in a range of 75% to 95% in total, and martensite in a range of 5% to 20%, in which a boundary having an orientation difference of equal to or greater than 15° is set as a grain boundary, and in a case where an area which is surrounded by the grain boundary, and has an equivalent circle diameter of equal to or greater than 0.3 ⁇ m is defined as a grain, the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° is, by area ratio, in a range of 10% to 60%.
  • the present invention will be described more specifically with reference to examples of the hot-rolled steel sheet of the present invention.
  • the present invention is not limited to Example described below, and can be implemented by being properly modified the extent that it can satisfy the object before and after description, which are all included in the technical range of the present invention.
  • the steel having the chemical composition indicated in the following Table 1 was melted, and continuous cast so as to produce a slab. Then, the slab was heated at a temperature indicated in Table 2, and was subjected to rough rolling. After the rough rolling, the finish rolling was performed under the conditions indicated in Table 2 so as to obtain a hot-rolled steel sheet having the sheet thickness in a range of 2.2 to 3.4 mm.
  • Ar3 (°C) indicated in Table 2 was obtained from the chemical composition indicated in Table 1 using the following Expression (2).
  • Ar 3 970 ⁇ 325 ⁇ C + 33 ⁇ Si ⁇ 287 ⁇ P + 40 ⁇ Al ⁇ 92 ⁇ Mn + Mo + Cu ⁇ 46 ⁇ Cr + Ni
  • [C], [Si], [P], [Al], [Mn], [Mo], [Cu], [Cr], and [Ni] each represent, by mass%, the amount of each of C, Si, P, Al, Mn, Mo, Cu, Cr, and Ni, by mass%, and in a case of not containing the elements, 0 is substituted.
  • the blank column in Table 1 means that the analysis value was less than the detection limit.
  • each structure fraction (the area ratio), and the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° were obtained.
  • the structure fraction (the area ratio) was obtained using the following method. First, a sample collected from the hot-rolled steel sheet was etched using nital. After etching, a structure photograph obtained at a 1/4 thickness position in a visual field of 300 ⁇ m ⁇ 300 ⁇ m using an optical microscope was subjected to image analysis, and thereby the area ratio of ferrite and pearlite, and the total area ratio bainite and martensite were obtained.
  • the volume fraction of the residual austenite was obtained through X-ray diffraction measurement.
  • the volume fraction of the residual austenite was equivalent to the area ratio, and thus was set as the area ratio of the residual austenite.
  • the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° was measured using the following method.
  • the EBSD analysis was performed using an apparatus which is configured to include a thermal field emission scanning electron microscope (JSM-7001F, manufactured by JEOL) and an EBSD detector (HIKARI detector manufactured by TSL), at an analysis speed in a range of 200 to 300 points per second.
  • an area having the orientation difference of equal to or greater than 15° and an equivalent circle diameter of equal to or greater than 0.3 ⁇ m was defined as a grain, the average intragranular orientation difference of the grains was calculated, and the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° was obtained.
  • the grain defined as described above and the average intragranular orientation difference can be calculated using software "OIM Analysis (trademark)" attached to an EBSD analyzer.
  • the yield strength and the tensile strength were obtained in the tensile test, and the limit forming height was obtained by the saddle type stretch flange test.
  • a product of tensile strength (MPa) and limit forming height (mm) was evaluated as an index of the stretch flangeability, and in a case where the product thereof is equal to or greater than 19500 mm ⁇ MPa, it was determined that the steel sheet was excellent in the stretch flangeability.
  • the tensile test was performed based on JIS Z 2241 using tensile test pieces No. 5 of JIS which were collected in the longitudinal direction which is orthogonal to the rolling direction.
  • the saddle type stretch flange test was conducted by setting a clearance at the time of punching a corner portion to 11% using a saddle-type formed product in which a radius of curvature R of a corner was set to 60 mm, and an opening angle ⁇ was set to 120°.
  • the existence of the cracks having a length of 1/3 of the sheet thickness were visually observed after forming, and then a forming height of the limit in which the cracks were not present was determined as the limit forming height.
  • the chemical composition was outside the range of the present invention, and thus any one or both of the structure observed using the optical microscope and the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° did not satisfy the range of the present invention. As a result, the stretch flangeability did not satisfy the target value. In addition, in some examples, the tensile strength is also decreased.
  • Nos. 24 to 36 are examples in which the manufacturing method was outside the preferable range, and thus any one or both of the structure observed using the optical microscope and the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° did not satisfy the range of the present invention.
  • the stretch flangeability did not satisfy the target value.
  • the tensile strength was also decreased.
  • an high-strength hot-rolled steel sheet which is excellent in the stretch flangeability and can be applied to a member which requires high strength and the strict stretch flangeability.
  • the steel sheet contributes to improving fuel economy of vehicles, and thus has high industrial applicability.

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Families Citing this family (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016132549A1 (ja) * 2015-02-20 2016-08-25 新日鐵住金株式会社 熱延鋼板
EP3260565B1 (en) * 2015-02-20 2019-07-31 Nippon Steel Corporation Hot-rolled steel sheet
PL3263729T3 (pl) * 2015-02-25 2020-05-18 Nippon Steel Corporation Blacha stalowa cienka walcowana na gorąco
WO2016135898A1 (ja) 2015-02-25 2016-09-01 新日鐵住金株式会社 熱延鋼板
KR102205432B1 (ko) 2016-08-05 2021-01-20 닛폰세이테츠 가부시키가이샤 강판 및 도금 강판
BR112019000766B8 (pt) 2016-08-05 2023-03-14 Nippon Steel & Sumitomo Metal Corp Chapa de aço
EP3778951A4 (en) * 2018-03-29 2021-10-27 Nippon Steel Corporation HOT PUNCHED SHAPED PRODUCT
CN112585289B (zh) * 2018-08-23 2022-04-29 杰富意钢铁株式会社 热轧钢板及其制造方法
CN113840936B (zh) 2019-05-31 2022-06-17 日本制铁株式会社 热冲压成型体
KR102603495B1 (ko) 2019-05-31 2023-11-20 닛폰세이테츠 가부시키가이샤 핫 스탬프 성형체
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JP7231022B2 (ja) 2019-05-31 2023-03-01 日本製鉄株式会社 ホットスタンプ成形体
WO2020241257A1 (ja) 2019-05-31 2020-12-03 日本製鉄株式会社 ホットスタンプ用鋼板
CN113906152B (zh) 2019-05-31 2022-11-01 日本制铁株式会社 热压成型体
US20230001466A1 (en) * 2020-01-09 2023-01-05 Nippon Steel Corporation Hot-stamping formed body

Family Cites Families (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0949026A (ja) * 1995-08-07 1997-02-18 Kobe Steel Ltd 強度−伸びバランス及び伸びフランジ性にすぐれる高強度熱延鋼板の製造方法
DE60045303D1 (de) * 1999-09-29 2011-01-13 Jfe Steel Corp Stahlblech und verfahren zu dessen herstellung
JP4258934B2 (ja) * 2000-01-17 2009-04-30 Ｊｆｅスチール株式会社 加工性と疲労特性に優れた高強度熱延鋼板およびその製造方法
JP4306076B2 (ja) * 2000-02-02 2009-07-29 Ｊｆｅスチール株式会社 伸びフランジ性に優れた高延性熱延鋼板およびその製造方法
JP4445095B2 (ja) 2000-04-21 2010-04-07 新日本製鐵株式会社 バーリング加工性に優れる複合組織鋼板およびその製造方法
JP2002226943A (ja) * 2001-02-01 2002-08-14 Kawasaki Steel Corp 加工性に優れた高降伏比型高張力熱延鋼板およびその製造方法
JP4062118B2 (ja) * 2002-03-22 2008-03-19 Ｊｆｅスチール株式会社 伸び特性および伸びフランジ特性に優れた高張力熱延鋼板とその製造方法
JP4333379B2 (ja) 2004-01-29 2009-09-16 Ｊｆｅスチール株式会社 加工性、表面性状および板平坦度に優れた高強度薄鋼板の製造方法
JP4470701B2 (ja) * 2004-01-29 2010-06-02 Ｊｆｅスチール株式会社 加工性および表面性状に優れた高強度薄鋼板およびその製造方法
JP5228447B2 (ja) * 2006-11-07 2013-07-03 新日鐵住金株式会社 高ヤング率鋼板及びその製造方法
JP5037415B2 (ja) * 2007-06-12 2012-09-26 新日本製鐵株式会社 穴広げ性に優れた高ヤング率鋼板及びその製造方法
JP4980163B2 (ja) * 2007-07-20 2012-07-18 新日本製鐵株式会社 成形性に優れる複合組織鋼板およびその製造方法
JP5200653B2 (ja) * 2008-05-09 2013-06-05 新日鐵住金株式会社 熱間圧延鋼板およびその製造方法
JP5438302B2 (ja) * 2008-10-30 2014-03-12 株式会社神戸製鋼所 加工性に優れた高降伏比高強度の溶融亜鉛めっき鋼板または合金化溶融亜鉛めっき鋼板とその製造方法
JP5719545B2 (ja) * 2010-08-13 2015-05-20 新日鐵住金株式会社 伸びとプレス成形安定性に優れた高強度薄鋼板
US9670569B2 (en) * 2011-03-28 2017-06-06 Nippon Steel & Sumitomo Metal Corporation Cold-rolled steel sheet and production method thereof
CN103562428B (zh) * 2011-05-25 2015-11-25 新日铁住金株式会社 冷轧钢板及其制造方法
JP5640898B2 (ja) * 2011-06-02 2014-12-17 新日鐵住金株式会社 熱延鋼板
JP5780210B2 (ja) 2011-06-14 2015-09-16 新日鐵住金株式会社 伸びと穴広げ性に優れた高強度熱延鋼板およびその製造方法
RU2567960C1 (ru) * 2011-09-30 2015-11-10 Ниппон Стил Энд Сумитомо Метал Корпорейшн Высокопрочный гальванизированный горячим погружением стальной лист
JP5825225B2 (ja) * 2012-08-20 2015-12-02 新日鐵住金株式会社 熱延鋼板の製造方法
RU2605014C2 (ru) * 2012-09-26 2016-12-20 Ниппон Стил Энд Сумитомо Метал Корпорейшн Лист двухфазной стали и способ его изготовления
BR112015024840B1 (pt) * 2013-04-15 2020-03-31 Nippon Steel Corporation Chapa de aço laminada a quente

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None *

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