EP3239331B1 - Hochfester stahl mit hervorragender sprödbruchstablität und herstellungsverfahren dafür - Google Patents

Hochfester stahl mit hervorragender sprödbruchstablität und herstellungsverfahren dafür Download PDF

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EP3239331B1
EP3239331B1 EP15873589.4A EP15873589A EP3239331B1 EP 3239331 B1 EP3239331 B1 EP 3239331B1 EP 15873589 A EP15873589 A EP 15873589A EP 3239331 B1 EP3239331 B1 EP 3239331B1
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steel
steel sheet
thickness
central portion
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French (fr)
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EP3239331A4 (de
EP3239331A1 (de
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Hak-Cheol Lee
Sung-Ho Jang
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Posco Holdings Inc
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Posco Co Ltd
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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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES, PROFILES OR LIKE SEMI-MANUFACTURED PRODUCTS OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C37/00—Manufacture of metal sheets, rods, wire, tubes, profiles or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape
    • B21C37/02—Manufacture of metal sheets, rods, wire, tubes, profiles or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape of sheets
    • 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
    • C21D6/005—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 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
    • C21D8/021—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 involving particular fabrication steps or treatments of ingots or slabs
    • 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
    • C21D8/0226—Hot 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
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/08—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
    • C22C38/12—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
    • C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
    • 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
    • C21D2201/00—Treatment for obtaining particular effects
    • C21D2201/05—Grain orientation
    • 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
    • C21D2211/009—Pearlite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties 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
    • C21D8/0263—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 following hot rolling

Definitions

  • the present disclosure relates to a high-strength steel having excellent brittle crack arrestability and a method of manufacturing the same.
  • brittle crack arrestability referring to stability of a structure
  • a high-strength steel is applied to a major structure such as a ship, or the like
  • cases in which guaranteed levels of brittle crack arrestability are required have increased.
  • a low temperature transformation phase is generated in a central portion, a phenomenon in which brittle crack arrestability is significantly reduced occurs. Therefore, it may be difficult to improve brittle crack arrestability of an extremely thick high-strength steel.
  • EP 2 660 346 describes a high-strength steel sheet superior toughness at cryogenic temperatures, and a method for manufacturing the same.
  • KR 100 723 201 B1 describes thick steel plates for ship building.
  • An aspect of the present disclosure is to provide a high-strength steel having excellent brittle crack arrestability.
  • Another aspect of the present disclosure is to provide a method of manufacturing a high-strength steel having excellent brittle crack arrestability.
  • a high-strength steel sheet having excellent brittle crack arrestability includes 0.05 wt% to 0.1 wt% of carbon (C), 0.9 wt% to 1.5 wt% of manganese (Mn), 0.8 wt% to 1.5 wt% of nickel (Ni), 0.005 wt% to 0.1 wt% of niobium (Nb), 0.005 wt% to 0.1 wt% of titanium (Ti), 0.1 wt% to 0.6 wt% of copper (Cu), 0.1 wt% to 0.4 wt% of silicon (Si), 100 ppm or less of phosphorous (P), 40 ppm or less of sulfur (S), and the remainder being iron (Fe) and other inevitably contained impurities, the high-strength steel having a microstructure being one structure selected from the group consisting of a single-phase structure of ferrite, a single-phase structure of bainite, a complex
  • a fraction of pearlite may be 20% or less.
  • the steel thickness may be 80mm to 100mm.
  • a method of manufacturing a high-strength steel sheet having excellent brittle crack arrestability includes: reheating a slab at 950°C to 1100°C, the steel of the slab consisting of 0.05 wt% to 0.1 wt % of carbon (C), 0.9 wt% to 1.5 wt% of manganese (Mn), 0.8 wt% to 1.5 wt% of nickel (Ni), 0.005 wt% to 0.1 wt% of niobium (Nb), 0.005 wt% to 0.1 wt% of titanium (Ti), 0.1 wt% to 0.6 wt% of copper (Cu), 0.1 wt% to 0.4 wt% of silicon (Si), 100 ppm or less of phosphorous (P), 40 ppm or less of sulfur (S), and the remainder being iron (Fe) and other inevitably contained impurities, and then rough rolling the slab at a temperature of 1100°C to
  • a reduction ratio per pass with respect to three final passes may be 5% or more, and a total cumulative reduction ratio may be 40% or more.
  • a crystal grain size of a central portion of the bar in a thickness direction before the finish rolling after the rough rolling may preferably be 150 ⁇ m or less, and more preferably 100 ⁇ m or less.
  • a reduction ratio during the finish rolling may be set such that a ratio of a slab thickness (mm) / a steel sheet thickness (mm) after finish rolling may be 3.5 or above, preferably 3.8 or above.
  • the cooling of the steel sheet is performed at a cooling rate of a central portion of the steel sheet in a thickness direction of 2°C/s or more.
  • the cooling of the steel sheet may be performed at an average cooling rate from 3°C/s to 300°C/s.
  • a high-strength steel having high yield strength and excellent brittle crack arrestability is obtained.
  • FIG. 1 is an image of a central portion of Inventive steel 1 in a thickness direction, captured with an optical microscope.
  • the inventors conducted research and experiments into improving yield strength and brittle crack arrestability of a thick steel having a thickness of 50 mm or more, and the present disclosure has been proposed based on the results thereof.
  • a steel composition, a structure, a texture, and manufacturing conditions of a steel are controlled, so yield strength and brittle crack arrestability of a steel having a thick thickness are further improved.
  • a main concept in the present disclosure is as follows.
  • a pressing condition is controlled, and a sufficient temperature difference between a central portion and a surface is secured, so a fine structure is secured in a central portion of a steel.
  • a high-strength steel having excellent brittle crack arrestability includes the features as defined in claim 1.
  • C is the most important element in securing basic strength, so C needs to be contained in a steel in an appropriate range. In order to obtain such an additive effect, C is added in an amount of 0.05% or more.
  • the content of C exceeds 0.10%, due to the generation of a large amount of martensite-austenite constituent (MA), high strength of ferrite itself, and generation of a large amount of a low temperature transformation phase, or the like, low temperature toughness may be reduced.
  • the content of C is limited to 0.05% to 0.10%, preferably limited to 0.061% to 0.091%, and more preferably limited to 0.065% to 0.085%.
  • Mn is a useful element for improving strength due to solid solution strengthening and for improving hardenability to allow a low temperature transformation phase to be generated.
  • Mn is added in an amount of 0.9% or more.
  • the content of Mn is limited to 0.9% to 1.5%, preferably limited to 0.97% to 1.39%, and more preferably limited to 1.15% to 1.30%.
  • Ni is an important element, allowing dislocation cross-slip to be easily performed at a low temperature to improve impact toughness, and improving hardenability to improve strength.
  • Ni is added in an amount of 0.8% or more.
  • hardenability is excessively increased, so a low temperature transformation phase is generated.
  • toughness may be reduced and manufacturing costs may be increased.
  • an upper limit of the content of Ni is limited to 1.5%.
  • the content of Ni is preferably limited to 0.89% to 1.42% and more preferably limited to 1.01% to 1.35 %.
  • Nb is precipitated in the form of NbC or NbCN, thereby improving strength of a base material.
  • Nb dissolved during reheating at a high temperature, is significantly finely precipitated in the form of NbC during rolling, so recrystallization of austenite is suppressed.
  • a structure may be refined.
  • Nb is added in an amount of 0.005% or more.
  • an upper limit of the content of Nb is limited to 0.1%.
  • the content of Nb is preferably limited to 0.012% to 0.028% and more preferably limited to 0.018% to 0.024%.
  • Ti is precipitated as TiN during reheating, and thus inhibits growth of a crystal grain in a base material and in a weld heat affected zone, thereby significantly improving low temperature toughness.
  • Ti is added in an amount of 0.005% or more.
  • Ti when Ti is added in an amount exceeding 0.1%, a continuous casting nozzle may be clogged, or low temperature toughness may be reduced by crystallization of a central portion. In this case, the content of Ti is limited to 0.005% to 0.1%.
  • the content of Ti is preferably limited to 0.009% to 0.024% and more preferably limited to 0.011% to 0.018%.
  • P and S are elements causing brittleness in a grain boundary or causing brittleness by forming a coarse inclusion.
  • P is limited to 100 ppm or less and S is limited to 40 ppm or less.
  • Si improves strength of a steel and has a strong deoxidizing effect, and thus is an essential element in producing clean steel.
  • Si is added in an amount of 0.1% or more.
  • an upper limit of the content of Si is limited to 0.4%.
  • the content of Si is preferably limited to 0.22% to 0.32% and more preferably limited to 0.25% to 0.3 %.
  • Cu is a main element in improving strength of a steel by improving hardenability and causing solid solution strengthening, and is a main element in increasing a yield strength due to generation of ⁇ (epsilon) Cu precipitate when tempering is applied.
  • ⁇ epsilon
  • Cu is added in an amount of 0.1% or more.
  • an upper limit of the content of Cu is limited to 0.6%.
  • the content of Cu is preferably limited to 0.21% to 0.51% and more preferably is limited to 0.18% to 0.3%.
  • the contents of Cu and Ni are set such that a Cu/Ni weight ratio is 0.6 or less and preferably 0.5 or less.
  • iron (Fe) is provided as a remainder thereof.
  • the impurities may be known to those skilled in the art, and thus, may not be particularly described in this specification.
  • the steel according to an exemplary embodiment has a microstructure including a single structure selected from the group consisting of a single-phase structure of ferrite, a single-phase structure of bainite, a complex-phase structure of ferrite and bainite, a complex-phase structure of ferrite and pearlite, and a complex-phase structure of ferrite, bainite, and pearlite.
  • the ferrite is polygonal ferrite or acicular ferrite, and the bainite is preferably granular bainite.
  • fraction of pearlite is preferably limited to 20% or less.
  • a grain size having a high-angle boundary of 15 degrees or more, measured in an EBSD method, in a central portion is 30 ⁇ m or less.
  • the grain size of a structure of a central portion of the steel is refined to be 30 ⁇ m or less, so strength is improved due to strengthening by grain refinement, while brittle crack arrestability is improved by significantly reducing the generation and propagation of cracks.
  • An area ratio of a (100) plane forming an angle within 15 degrees with respect to a plane perpendicular to a rolling direction in a region of the high-strength steel in a range of 20% of an overall steel thickness based on a position equal to 1/2 of the steel thickness is 40% or less.
  • a crack is propagated in a width direction of a steel, that is, in a direction perpendicular to a rolling direction, and a brittle fracture surface of a body-centered cubic structure (BCC) is a (100) plane.
  • BCC body-centered cubic structure
  • a texture of an area of a central portion in which a microstructure is relatively coarse in comparison with a surface is controlled.
  • a texture of a steel and, particularly, an area ratio of a (100) plane forming an angle within 15 degrees with respect to a plane perpendicular to a rolling direction in a region of the high-strength steel in a range of 20% of an overall steel thickness based on a position equal to 1/2 of the steel thickness is controlled to be 40% or less. Even when a crack is generated, propagation of the crack is significantly reduced, so brittle crack arrestability is improved.
  • the steel has a yield strength of 390 MPa or more.
  • the steel has a thickness of 50 mm or more, preferably has a thickness of 50 mm to 100 mm, and more preferably has a thickness of 80 mm to 100 mm.
  • a method of manufacturing a high-strength steel is defined in claim 4.
  • a slab is reheated before rough rolling.
  • a reheating temperature of a slab is set to be 950 °C or more, to dissolve carbonitride of Ti and/or Nb formed during casting.
  • it is preferably to heat at 1000°C or more.
  • austenite may be coarsened.
  • an upper limit of the reheating temperature is limited to 1100°C.
  • the slab, having been reheated, is rough rolled.
  • a rough rolling temperature is a temperature (Tnr) at which recrystallization of austenite is stopped or more. Due to rolling, effects in which a casting structure such as a dendrite formed during casting or the like is destroyed and a size of austenite is reduced may be obtained. To obtain the effects described above, the rough rolling temperature is limited to 1100°C to 900°C.
  • a temperature difference between a central portion and a surface of the slab or bar immediately before the rough rolling should be 100°C to 300°C.
  • a surface of the slab or bar maintains a temperature lower than that of a central portion. While the temperature difference exists, when rough rolling is performed, more deformation occurs in a central portion in which a temperature is relatively high than in the surface in which a temperature is relatively low. Thus, a crystal grain size of a central portion is more refined. In this case, an average grain size of a central portion is maintained to be 30 ⁇ m or less.
  • a phenomenon in which the surface in which a temperature is relatively low has strength higher than that of a central portion in which a temperature is relatively high, so more deformation occurs in a central portion having relatively low strength, is used.
  • a temperature difference between a central portion and a surface is 100°C to 300°C.
  • the temperature difference between a central portion and a surface of the slab or bar indicates a difference between a temperature of a surface of the slab or bar measured immediately before rough rolling, and a temperature of a central portion, calculated in consideration of a cooling condition and a thickness of the slab or bar immediately before rough rolling.
  • Measuring of a temperature of a surface and a thickness of the slab is performed before first rough rolling, and measuring of a temperature of a surface and a thickness of the bar is performed before rough rolling, starting from a second process of rough rolling.
  • a temperature difference between a central portion and a surface of the slab or bar indicates that a temperature difference, in which a temperature difference for each pass of rough rolling is measured and a total average value is calculated, is 100°C to 300°C.
  • a reduction ratio per pass is 5% or more, and a total cumulative reduction ratio is preferably 40% or more.
  • a reduction ratio per pass of rough rolling is lowered, sufficient deformation is not transferred to a central portion, so toughness degradation caused by coarsening of a central portion may occur.
  • a reduction ratio per pass of three final passes is preferably limited to 5% or more.
  • a total cumulative reduction ratio during rough rolling is preferably set to be 40% or more.
  • the bar having been rough rolled is finish rolled at 850°C to Ar 3 (a ferrite transformation start temperature), so a steel sheet is obtained.
  • a finish rolling temperature of finish rolling is 850°C or less.
  • a crystal grain size of a central portion of a bar before finish rolling after the rough rolling is 200 ⁇ m or less, preferably 150 ⁇ m or less, and more preferably 100 ⁇ m or less.
  • the crystal grain size of a central portion of a bar before finish rolling after the rough rolling may be controlled according to a rough rolling condition, or the like.
  • a reduction ratio during the finish rolling may be set such that a ratio of a slab thickness (mm)/a steel sheet thickness (mm) after finish rolling is 3.5 or above, preferably 3.8 or more.
  • a steel sheet After finish rolling, a steel sheet has a thickness of 50 mm or more, preferably has a thickness of 50 mm to 100 mm, and more preferably has a thickness 80 mm to 100 mm.
  • a steel sheet After finish rolling, a steel sheet is cooled to 700°C or less When a cooling end temperature exceeds 700°C, a microstructure is not properly formed, so yield strength may be 390 Mpa or less.
  • Cooling of the steel sheet is performed at a cooling rate of a central portion of the steel sheet in a thickness direction of 2°C/s or more.
  • a cooling rate of a central portion of the steel sheet in a thickness direction is less than 2°C/s, a microstructure is not properly formed, so yield strength may be 390 Mpa or less.
  • cooling of the steel sheet may be performed at an average cooling rate from 3°C/s to 300°C/s.
  • the average temperature difference between a central portion and a surface during rough rolling of Table 2 refers to a difference between a temperature of a surface of a slab or bar measured immediately before rough rolling, and a temperature of a central portion calculated in consideration of an amount of water sprayed to a bar and a slab thickness immediately before rough rolling, and is a result in which a temperature difference for each pass of rough rolling is measured and a total average value is calculated.
  • a thickness of the bar having been rough rolled was 180 mm, and a crystal grain size before finish rolling after rough rolling was 80 ⁇ m.
  • finish rolling was performed at a finish rolling temperature of 770°C, so a steel sheet having a thickness of Table 2 was obtained, and cooling was performed to a temperature of 700°C or less at a cooling rate of 5°C/sec thereafter.
  • a microstructure, yield strength, an average grain size of a central portion measured in EBSD, an area ratio of a (100) plane forming an angle within 15 degrees with respect to a plane perpendicular to a rolling direction in a region of the high-strength steel in a range of 20% of an overall steel thickness based on a position equal to 1/2 of the steel thickness, a Kca value (a brittle crack arrestability coefficient) were investigated, and a result thereof is illustrated in Table 2.
  • a Kca value of Table 2 is a value evaluated by performing an ESSO test with respect to a steel sheet.
  • Steel Grade Steel Composition (Weight%) C Si Mn Ni Cu Ti Nb P (ppm) S (ppm) Cu/Ni weight ratio Inventive steel 1 0.061 0.23 1.25 0.89 0.35 0.015 0.019 75 16 0.39 Inventive steel 2 0.082 0.31 1.36 0.95 0.44 0.016 0.017 77 25 0.46 Inventive steel 3 0.054 0.32 1.09 1.26 0.36 0.009 0.023 82 34 0.29 Inventive steel 4 0.072 0.22 1.39 1.13 0.21 0.024 0.012 65 19 0.19 Inventive steel 5 0.069 0.29 1.17 1.21 0.45 0.02 0.019 68 22 0.36 Inventive steel 6 0.091 0.31 0.97 1.42 0.51 0.019 0.028 71 31 0.36 Comparative steel 1 0.072 0.25 1.21 0.97 0.36 0.017 0.026 69 16 0.37 Comparative steel 2 0.
  • an average temperature difference between a central portion and a surface during rough rolling presented in the present disclosure is controlled to be less than 70°C.
  • a grain size of a central portion is 35.4 pm
  • an area ratio of a (100) plane forming an angle within 15 degrees with respect to a plane perpendicular to a rolling direction in a region of the high-strength steel in a range of 20% of an overall steel thickness based on a position equal to 1/2 of the steel thickness is 40% or more
  • a Kca value measured at -10°C does not exceed 6000, required for steel for shipbuilding according to the related art.
  • the content of C has a value higher than an upper limit of the content of C according to the present disclosure.
  • a grain size of austenite of a central portion is refined, but upper bainite is generated.
  • a grain size of a final microstructure is 38.3 pm
  • an area ratio of a (100) plane forming an angle within 15 degrees with respect to a plane perpendicular to a rolling direction in a region of the high-strength steel in a range of 20% of an overall steel thickness based on a position equal to 1/2 of the steel thickness is 40% or more.
  • upper bainite in which brittleness may easily occur is included as a base structure, so a Kca value is a value of 6000 or less at -10°C.
  • the content of Si has a value higher than an upper limit of the content of Si according to the present disclosure.
  • a grain size of austenite of a central portion is refined, but upper bainite is partially generated in a central portion.
  • a Kca value is a value of 6000 or less at -10°C.
  • the content of Mn has a value higher than an upper limit of the content of Mn according to the present disclosure.
  • a microstructure of a base material is upper bainite.
  • an area ratio of a (100) plane forming an angle within 15 degrees with respect to a plane perpendicular to a rolling direction in a region of the high-strength steel in a range of 20% of an overall steel thickness based on a position equal to 1/2 of the steel thickness is 40% or more
  • a Kca value is a value of 6000 or less at -10°C.
  • the content of Ni has a value higher than an upper limit of the content of Ni according to the present disclosure. Due to high hardenability, a microstructure of a base material is granular bainite and upper bainite. When rough rolling is performed, through cooling, a grain size of austenite of a central portion is refined, but a grain size of a final microstructure is 31.2 ⁇ m, and a Kca value is a value of 6000 or less at -10°C.
  • a Kca value is a value of 6000 or less at -10°C.
  • Inventive steel 1 through 6 satisfying a composition range according to the present disclosure and in which a grain size of austenite of a central portion is refined through cooling during rough rolling, yield strength satisfies 390 MPa or more, and a grain size of a central portion satisfies 30 ⁇ m or less.
  • a complex-phase structure of ferrite and pearlite, a single-phase structure of acicular ferrite, or a complex-phase structure of acicular ferrite and granular bainite is included as a microstructure.
  • an area ratio of a (100) plane forming an angle within 15 degrees with respect to a plane perpendicular to a rolling direction in a region of the high-strength steel in a range of 20% of an overall steel thickness based on a position equal to 1/2 of the steel thickness is 40% or less, and a Kca value satisfies a value of 6000 or more at -10°C.
  • FIG. 1 is an image of a central portion of Inventive steel 1 in a thickness direction captured with an optical microscope. As illustrated in FIG. 1 , it is confirmed that a structure of a central portion in a thickness direction is refined.

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Claims (7)

  1. Hochfestes Stahlblech, das eine ausgezeichnete Sprödrisshemmfähigkeit aufweist, wobei das hochfeste Stahl des Blechs aus Folgendem besteht:
    0,05 Gew.-% bis 0,1 Gew.-% Kohlenstoff (C), 0,9 Gew.-% bis 1,5 Gew.-% Mangan (Mn), 0,8 Gew.-% bis 1,5 Gew.-% Nickel (Ni), 0,005 Gew.-% bis 0,1 Gew.-% Niob (Nb), 0,005 Gew.-% bis 0,1 Gew.-% Titan (Ti), 0,1 Gew.-% bis 0,6 Gew.-% Kupfer (Cu), 0,1 Gew.-% bis 0,4 Gew.-% Silicium (Si), 100 ppm oder weniger Phosphor (P), 40 ppm oder weniger Schwefel (S), und wobei der Rest aus Eisen (Fe) und anderen unvermeidlich enthaltenen Verunreinigungen besteht, wobei der hochfeste Stahl mit einer Mikrostruktur eine Struktur hat, die aus der Gruppe ausgewählt ist, die aus einer Einphasenstruktur von Ferrit; einer Einphasenstruktur aus Bainit; einer Komplexphasenstruktur aus Ferrit und Bainit; einer Komplexphasenstruktur aus Ferrit und Perlit und einer Komplexphasenstruktur aus Ferrit, Bainit und Perlit mit einer Dicke von 50 mm oder mehr besteht, wobei die Gehalte an Cu und Ni so eingestellt sind, dass ein Cu/Ni-Gewichtsverhältnis 0,6 oder weniger beträgt, wobei der Ferrit nadelförmiger Ferrit oder polygonaler Ferrit ist und der Bainit körniger Bainit ist, wobei in dem hochfesten Stahlblech eine Korngröße mit einer Hochwinkelgrenze von 15 Grad oder mehr, gemessen in einem Elektronenrückstreuungsbeugungsverfahren (electron backscattered diffraction, EBSD), in einem zentralen Abschnitt einer Stahldicke 30 µm oder weniger beträgt, wobei ein Flächenverhältnis von einer (100) Ebene, die einen Winkel innerhalb von 15 Grad in Bezug auf eine Ebene senkrecht zu einer Walzrichtung in einem Bereich des hochfesten Stahlblechs in einem Bereich von 20 % einer Gesamtstahldicke bildet, basierend auf einer Position gleich 1/2 der Stahldicke 40 % oder weniger beträgt, und wobei die Streckgrenze des hochfesten Stahls 390 MPa oder mehr beträgt.
  2. Hochfestes Stahlblech mit ausgezeichneter Sprödrisshemmfähigkeit nach Anspruch 1, wobei, wenn die Mikrostruktur des Stahls eine Komplexphasenstruktur einschließlich Perlit ist, ein Anteil an Perlit 20 % oder weniger beträgt.
  3. Hochfestes Stahlblech mit ausgezeichneter Sprödrisshemmfähigkeit nach Anspruch 1, wobei eine Stahldicke 80 mm bis 100 mm beträgt.
  4. Verfahren zum Herstellen eines hochfesten Stahlblechs, das die ausgezeichnete Sprödrisshemmfähigkeit gemäß Anspruch 1 aufweist, wobei das Verfahren umfasst:
    Wiedererhitzen einer Bramme auf eine Temperatur zwischen 950 °C und 1.100 °C und anschließendes Grobwalzen der Bramme bei einer Temperatur zwischen 1.100 °C und 900 °C, wobei die Bramme aus 0,05 Gew.-% bis 0,1 Gew.-% Kohlenstoff (C), 0,9 Gew.-% bis 1,5 Gew.-% Mangan (Mn), 0,8 Gew.-% bis 1,5 Gew.-% Nickel (Ni), 0,005 Gew.-% bis 0,1 Gew.-% Niob (Nb), 0,005 Gew.-% bis 0,1 Gew.-% Titan (Ti), 0,1 Gew.-% bis 0,6 Gew.-% Kupfer (Cu), 0,1 Gew.-% bis 0,4 Gew.-% Silicium (Si), höchstens 100 ppm Phosphor (P) und höchstens 40 ppm Schwefel (S) besteht, und wobei der Rest aus Eisen (Fe) und anderen unvermeidlich enthaltenen Verunreinigungen besteht;
    Erhalten eines Stahlblechs mit einer Dicke von 50 mm oder mehr durch Fertigwalzen eines grobgewalzten Stabes bei einer Temperatur von 850 °C auf Ar3; und
    Abkühlen des Stahlblechs auf eine Temperatur von 700 °C oder weniger, wobei die Gehalte an Cu und Ni so eingestellt sind, dass ein Cu/Ni-Gewichtsverhältnis 0,6 oder weniger beträgt, wobei das Grobwalzen in zwei oder mehr Durchgängen durchgeführt wird, wobei eine Außenfläche der Bramme oder Stange vor jedem Durchgang des Grobwalzens eine Temperatur aufrechthält, die niedriger als die eines Mittelabschnitts in Dickenrichtung ist, wobei ein Durchschnittswert der Temperaturunterschiede zwischen dem Mittelabschnitt in einer Dickenrichtung der Bramme oder des Stabes und einer Außenfläche der Bramme oder des Stabes unmittelbar vor jedem Durchgang des Rohwalzens 100 °C bis 300 °C beträgt, wobei die Temperaturunterschiede Unterschiede zwischen einer Temperatur einer Außenfläche der Bramme oder des Stabes sind, die unmittelbar vor jedem Durchgang des Grobwalzens gemessen wird, und einer Temperatur eines zentralen Abschnitts, unter Berücksichtigung eines Abkühlungszustands und einer Dicke der Bramme oder des Stabes, die unmittelbar vor jedem Durchgang des groben Walzens berechnet wird, wobei eine Kristallkorngröße eines zentralen Abschnitts des Stabes vor dem Fertigwalzen nach dem Grobwalzen 200 µm oder weniger beträgt, und wobei das Abkühlen des Blechs mit einer Abkühlgeschwindigkeit eines zentralen Abschnitts des Stahlblechs von 2 °C/s oder mehr durchgeführt wird.
  5. Verfahren zur Herstellung eines hochfesten Stahlblechs mit ausgezeichneter Sprödrisshemmfähigkeit nach Anspruch 4, wobei ein Reduktionsverhältnis pro Durchgang in Bezug auf drei Enddurchgänge, wenn das Grobwalzen durchgeführt wird, 5 % oder mehr beträgt und ein kumulatives Gesamtreduktionsverhältnis 40 % oder mehr beträgt.
  6. Verfahren zur Herstellung eines hochfesten Stahlblechs mit ausgezeichneter Sprödrisshemmfähigkeit nach Anspruch 4, wobei ein Reduktionsverhältnis während des Fertigwalzens so eingestellt wird, dass ein Verhältnis einer Plattendicke in mm zu einer Stahlblechdicke in mm nach dem Fertigwalzen 3,5 oder mehr beträgt.
  7. Verfahren zur Herstellung eines hochfesten Stahlblechs mit ausgezeichneter Sprödrisshemmfähigkeit nach Anspruch 4, wobei das Abkühlen des Stahlblechs mit einer durchschnittlichen Abkühlgeschwindigkeit von 3 °C/s bis 300 °C/s durchgeführt wird.
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Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3239332B1 (de) * 2014-12-24 2019-11-20 Posco Hochfester stahl mit hervorragender sprödbruchstablität und herstellungsverfahren dafür
US10822671B2 (en) 2014-12-24 2020-11-03 Posco High-strength steel having superior brittle crack arrestability, and production method therefor
JP6536514B2 (ja) * 2016-08-09 2019-07-03 Ｊｆｅスチール株式会社 脆性亀裂伝播停止特性に優れた構造用高強度厚鋼板およびその製造方法
JP6504131B2 (ja) * 2016-08-09 2019-04-24 Ｊｆｅスチール株式会社 高強度厚鋼板およびその製造方法
KR101917455B1 (ko) 2016-12-22 2018-11-09 주식회사 포스코 표면부 nrl-dwt 물성이 우수한 극후물 강재 및 그 제조방법
KR102209561B1 (ko) 2018-11-30 2021-01-28 주식회사 포스코 취성균열전파 저항성이 우수한 극후물 강재 및 그 제조방법
KR102209547B1 (ko) * 2018-12-19 2021-01-28 주식회사 포스코 취성균열개시 저항성이 우수한 구조용 극후물 강재 및 그 제조방법
JP7616164B2 (ja) * 2021-07-19 2025-01-17 Ｊｆｅスチール株式会社 鋼板およびその製造方法

Family Cites Families (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04180521A (ja) * 1990-11-14 1992-06-26 Kobe Steel Ltd 高降伏強度高靭性厚肉高張力鋼板の製造方法
JP3211046B2 (ja) * 1994-09-07 2001-09-25 新日本製鐵株式会社 溶接継手部の脆性破壊伝播停止性能の優れた溶接構造用厚鋼板の製造方法
JP3749616B2 (ja) * 1998-03-26 2006-03-01 新日本製鐵株式会社 超大入熱溶接熱影響部の靱性に優れた溶接用高張力鋼
JP4830330B2 (ja) * 2005-03-25 2011-12-07 Ｊｆｅスチール株式会社 厚肉低降伏比高張力鋼板の製造方法
KR100723201B1 (ko) * 2005-12-16 2007-05-29 주식회사 포스코 다층용접부 인성이 우수한 고강도 고인성 강 및 그제조방법
KR100660230B1 (ko) * 2005-12-26 2006-12-21 주식회사 포스코 두께 중심부의 강도와 인성이 우수한 용접구조용 극후물강판 및 그 제조방법
JP4058097B2 (ja) * 2006-04-13 2008-03-05 新日本製鐵株式会社 アレスト性に優れた高強度厚鋼板
JP5064150B2 (ja) * 2006-12-14 2012-10-31 新日本製鐵株式会社 脆性き裂伝播停止性能に優れた高強度厚鋼板
JP4309946B2 (ja) * 2007-03-05 2009-08-05 新日本製鐵株式会社 脆性き裂伝播停止特性に優れた厚手高強度鋼板およびその製造方法
KR100957964B1 (ko) * 2007-12-26 2010-05-17 주식회사 포스코 용접열영향부의 저온인성과 인장강도가 우수한 고강도저항복비 구조용 강재 및 그 제조방법
CN102271861B (zh) * 2009-01-14 2013-03-20 新日铁住金株式会社 耐脆性裂纹传播性优良的焊接结构体
KR101360737B1 (ko) * 2009-12-28 2014-02-07 주식회사 포스코 취성 균열 발생 저항성이 우수한 고강도 강판 및 그 제조방법
KR20120075274A (ko) * 2010-12-28 2012-07-06 주식회사 포스코 극저온 인성이 우수한 고강도 강판 및 그 제조방법
CN108130479A (zh) * 2011-02-08 2018-06-08 杰富意钢铁株式会社 长脆性裂纹传播停止特性优异的板厚为50mm以上的厚钢板及其制造方法
JP5304925B2 (ja) * 2011-12-27 2013-10-02 Ｊｆｅスチール株式会社 脆性亀裂伝播停止特性に優れた構造用高強度厚鋼板およびその製造方法
KR101681491B1 (ko) * 2011-12-27 2016-12-01 제이에프이 스틸 가부시키가이샤 취성 균열 전파 정지 특성이 우수한 고강도 후강판
TWI463018B (zh) * 2012-04-06 2014-12-01 Nippon Steel & Sumitomo Metal Corp 具優異裂縫阻滯性之高強度厚鋼板
JP2013221190A (ja) * 2012-04-17 2013-10-28 Nippon Steel & Sumitomo Metal Corp 脆性亀裂伝播停止性能に優れた高強度厚鋼板
JP2013221189A (ja) * 2012-04-17 2013-10-28 Nippon Steel & Sumitomo Metal Corp 脆性亀裂伝播停止性能に優れた高強度厚鋼板
KR20130134333A (ko) * 2012-05-30 2013-12-10 현대제철 주식회사 고강도 강판 및 그 제조 방법
KR20140098900A (ko) * 2013-01-31 2014-08-11 현대제철 주식회사 고강도 극후물 강판 및 그 제조 방법
EP3239332B1 (de) * 2014-12-24 2019-11-20 Posco Hochfester stahl mit hervorragender sprödbruchstablität und herstellungsverfahren dafür
US10822671B2 (en) * 2014-12-24 2020-11-03 Posco High-strength steel having superior brittle crack arrestability, and production method therefor

Non-Patent Citations (1)

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

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