WO2015037060A1 - Plaque d'acier pressée à chaud, article moulé à la presse, et procédé de fabrication d'article moulé à la presse - Google Patents

Plaque d'acier pressée à chaud, article moulé à la presse, et procédé de fabrication d'article moulé à la presse Download PDF

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WO2015037060A1
WO2015037060A1 PCT/JP2013/074426 JP2013074426W WO2015037060A1 WO 2015037060 A1 WO2015037060 A1 WO 2015037060A1 JP 2013074426 W JP2013074426 W JP 2013074426W WO 2015037060 A1 WO2015037060 A1 WO 2015037060A1
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press
less
area
amount
steel
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PCT/JP2013/074426
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Japanese (ja)
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村上　俊夫
純也 内藤
圭介 沖田
池田　周之
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株式会社神戸製鋼所
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Priority to CA3014626A priority Critical patent/CA3014626A1/fr
Priority to CA2923583A priority patent/CA2923583A1/fr
Priority to MX2016003260A priority patent/MX2016003260A/es
Priority to KR1020167006201A priority patent/KR101827187B1/ko
Priority to EP13893228.0A priority patent/EP3045553A4/fr
Priority to CN201380079439.1A priority patent/CN105518170A/zh
Priority to PCT/JP2013/074426 priority patent/WO2015037060A1/fr
Priority to US14/917,823 priority patent/US20160222482A1/en
Priority to RU2016111914A priority patent/RU2625357C1/ru
Publication of WO2015037060A1 publication Critical patent/WO2015037060A1/fr

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    • 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
    • C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
    • 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
    • C21D9/0068—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for particular articles not mentioned below
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D22/00—Shaping without cutting, by stamping, spinning, or deep-drawing
    • B21D22/02—Stamping using rigid devices or tools
    • B21D22/022—Stamping using rigid devices or tools by heating the blank or stamping associated with heat treatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D22/00—Shaping without cutting, by stamping, spinning, or deep-drawing
    • B21D22/20—Deep-drawing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D22/00—Shaping without cutting, by stamping, spinning, or deep-drawing
    • B21D22/20—Deep-drawing
    • B21D22/208—Deep-drawing by heating the blank or deep-drawing associated with heat treatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D22/00—Shaping without cutting, by stamping, spinning, or deep-drawing
    • B21D22/20—Deep-drawing
    • B21D22/28—Deep-drawing of cylindrical articles using consecutive dies
    • B21D22/286—Deep-drawing of cylindrical articles using consecutive dies with lubricating or cooling means
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    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
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    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C21D1/19—Hardening; Quenching with or without subsequent tempering by interrupted quenching
    • C21D1/20—Isothermal quenching, e.g. bainitic hardening
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    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
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    • C21—METALLURGY OF IRON
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    • 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
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    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
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    • 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
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    • 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
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    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
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    • 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
    • C22C38/14—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
    • C22C38/20—Ferrous alloys, e.g. steel alloys containing chromium with copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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    • 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
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    • 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
    • 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
    • C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/62—Quenching devices
    • C21D1/673—Quenching devices for die quenching
    • 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

Definitions

  • the present invention is used when manufacturing a structural part of an automobile, and is a hot-press steel sheet suitable for hot press forming, a press-formed product obtained from such a hot-press steel plate, and a press-formed product. It relates to a manufacturing method.
  • a preheated steel plate blade
  • the hot press steel plate is useful for application to a hot press forming method in which a heat treatment is performed simultaneously with shape formation to obtain a predetermined strength.
  • a press-formed product, and a useful method for producing such a press-formed product is used when manufacturing a structural part of an automobile, and is a hot-press steel sheet suitable for hot press forming, a press-formed product obtained from such a hot-press steel plate, and a press-formed product.
  • the steel sheet is heated to a predetermined temperature (for example, the temperature at which it becomes an austenite phase) to lower the strength, and then formed with a mold having a temperature lower than that of the steel sheet (for example, room temperature).
  • a hot press molding method is used for manufacturing a part (press-molded product) that performs quenching heat treatment (quenching) using the temperature difference between the two to ensure strength after molding.
  • a hot press forming method is called by various names such as a hot forming method, a hot stamping method, a hot stamp method, and a die quench method in addition to the hot press method.
  • FIG. 1 is a schematic explanatory diagram showing a mold configuration for carrying out hot press molding as described above.
  • 1 is a punch
  • 2 is a die
  • 3 is a blank holder
  • 4 is a steel plate (blank)
  • BHF is a crease pressing force
  • rp is a punch shoulder radius
  • rd is a die shoulder radius
  • CL is a punch / die clearance.
  • the punch 1 and the die 2 have passages 1a and 2a through which a cooling medium (for example, water) can pass, and the cooling medium is allowed to pass through the passages.
  • a cooling medium for example, water
  • the steel plate (blank) 4 is subjected to the two-phase region temperature (Ac 1 transformation point to Ac 3 transformation point) or Ac 3 transformation. Molding is started in a state of being softened by heating to a single-phase temperature above the point. That is, in a state where the steel plate 4 in a high temperature state is sandwiched between the die 2 and the blank holder 3, the steel plate 4 is pushed into the hole of the die 2 (between 2 and 2 in FIG. 1) by the punch 1, and the outer diameter of the steel plate 4 is reduced. A shape corresponding to the outer shape of the punch 1 is formed while shrinking.
  • a steel sheet for hot pressing that is widely used at present, a steel sheet made of 22MnB5 steel is known.
  • This steel sheet has a tensile strength of 1500 MPa and an elongation of about 6 to 8%, and is applied to an impact resistant member (a member that is not deformed as much as possible and does not break).
  • an impact resistant member a member that is not deformed as much as possible and does not break.
  • Patent Documents 1 to 4 As hot-press steel sheets exhibiting good elongation, for example, the techniques of Patent Documents 1 to 4 have been proposed. In these technologies, the basic strength class of each steel sheet is adjusted by setting the carbon content in the steel sheet to various ranges, and ferrite with high deformability is introduced, and the average of ferrite and martensite Elongation is improved by reducing the particle size. These techniques are effective for improving the elongation, but are still insufficient from the viewpoint of improving the elongation according to the strength of the steel sheet. For example, the tensile strength TS is 1470 MPa or more and the elongation EL is about 10.2% at the maximum, and further improvement is required.
  • the part where deformation should be prevented is high strength (high strength side: impact resistant part side), and the part requiring energy absorption is low strength and high ductility (low strength side: energy absorbing part side).
  • High strength side impact resistant part side
  • low strength side energy absorbing part side
  • Technology has been proposed.
  • impact resistance is included in the parts of the B pillar and rear side member in consideration of compatibility (a function to protect the other party when a small car collides) in a side collision or a rear collision. In some cases, it has both functional parts of energy absorption.
  • a tensile strength of 1500 MPa is achieved on the high strength side (impact resistant site side), but the maximum tensile strength is 700 MPa and the elongation EL is about 17% on the low strength side (energy absorption site side).
  • the energy absorption site side In order to further improve the energy absorption characteristics, it is required to realize higher strength and higher ductility.
  • Non-Patent Document 1 Although it is necessary to join automobile parts mainly by spot welding, it is known that the strength reduction in the welding heat affected zone (HAZ) is remarkable and the strength of the welded joint is reduced (softened) (for example, Non-Patent Document 1).
  • the present invention has been made in view of the above circumstances, and its purpose is to facilitate molding and processing before hot pressing, and when a uniform characteristic is required in a molded product, it has high strength. If a region corresponding to an impact resistant region and an energy absorbing region is required in a single molded product, it is possible to obtain a press molded product that can achieve a high balance between elongation and elongation. Steel sheet for hot pressing that can achieve a high balance between high strength and elongation at a high level, and that is useful in obtaining a press-formed product with good softening prevention characteristics in HAZ, and a press-formed product that exhibits the above characteristics And providing a useful method for producing such a press-formed product.
  • the steel sheet for hot pressing of the present invention that was able to achieve the above object, C: 0.15 to 0.5% (meaning mass%, hereinafter the same for chemical composition) Si: 0.2-3%, Mn: 0.5 to 3%, P: 0.05% or less (excluding 0%), S: 0.05% or less (excluding 0%), Al: 0.01 to 1%, B: 0.0002 to 0.01%, Ti: 3.4 [N] + 0.01% or more, 3.4 [N] + 0.1% or less (where [N] indicates the content (% by mass) of N), and N: 0.0010 ⁇ 0.01%, Each of which contains iron and inevitable impurities, Among the Ti-containing precipitates contained in the steel sheet, the average equivalent circle diameter of those having an equivalent circle diameter of 30 nm or less is 6 nm or less, and the relationship between the precipitated Ti amount in the steel and the total Ti amount in the following formula (1) And the metal structure is characterized in that the ferrite fraction is 30 area% or more.
  • the “equivalent circle diameter” means the diameter when converted to a circle of the same area when focusing on the size (area) of the Ti-containing precipitate (eg, TiC) (the “average equivalent circle diameter” is its average Value).
  • the hot press-forming steel sheet of the present invention it is also useful to contain at least one of the following (a) to (c) as other elements as required. Depending on the type of element contained as required, the properties of the press-formed product are further improved.
  • C 0.01% or less (excluding 0%) of at least one selected from the group consisting of Mg, Ca and REM
  • the method for producing a press-formed product of the present invention that has achieved the above-mentioned object includes the steel sheet for hot pressing of the present invention as described above having an Ac 1 transformation point of + 20 ° C. or higher and an Ac 3 transformation point of ⁇ 20 ° C. or lower. After heating to the above temperature, press forming of the steel sheet is started, and during the forming and after the forming is completed, a temperature lower by 100 ° C. than the bainite transformation start temperature Bs while ensuring an average cooling rate of 20 ° C./second or more in the mold. It is characterized by cooling to the following.
  • the metal structure of the press-formed product is as follows: retained austenite: 3 to 20 area%, ferrite: 30 to 80 area%, bainitic ferrite: less than 30 area% (excluding 0 area%) Martensite: 31 area% or less (excluding 0 area%), and among the Ti-containing precipitates contained in the press-formed product, the average equivalent circle diameter of the equivalent circle diameter of 30 nm or less is 10 nm or less.
  • the amount of precipitated Ti in the steel and the total amount of Ti satisfy the relationship of the following formula (1), and the balance between high strength and elongation can be achieved as a uniform characteristic at a high level in the molded product.
  • Precipitated Ti amount (mass%)-3.4 [N] ⁇ 0.5 ⁇ [Total Ti amount (mass%)-3.4 [N]] (1) (In the formula (1), [N] indicates the content (% by mass) of N in the steel)
  • another method for producing a press-formed product of the present invention that has achieved the above object is to use a steel sheet for hot pressing as described above, and divide the heating area of the steel sheet into at least two areas. region of Ac 3 transformation point or more, while heating to a temperature of 950 ° C. or less, the other one region Ac 1 transformation point + 20 ° C. or higher, then heated to Ac 3 transformation point -20 ° C. or less of the temperature, both Press molding is started for the region, and during molding and after completion of molding, the mold is cooled to a temperature below the martensite transformation start temperature Ms while ensuring an average cooling rate of 20 ° C./second or more in the mold. It is characterized by that.
  • Another press-formed product of the present invention is a steel plate press-formed product having the chemical composition as described above, and the press-formed product has a metal structure of retained austenite: 3 to 20 area%, martensite: The first region is 80 area% or more, and the metal structure is retained austenite: 3 to 20 area%, ferrite: 30 to 80 area%, bainitic ferrite: less than 30 area% (excluding 0 area%) , Martensite: having a second region that is 31 area% or less (not including 0 area%), and among the Ti-containing precipitates contained in the steel of this second region, the equivalent circle diameter is The average equivalent circle diameter of those having a thickness of 30 nm or less is 10 nm or less, and the amount of precipitated Ti in the steel and the total amount of Ti satisfy the relationship of the following formula (1).
  • the chemical component composition is strictly defined, the size of Ti-containing precipitates is controlled, the precipitation rate is controlled for Ti that does not form TiN, and the ferrite ratio for the metal structure. Since a steel sheet with adjusted thickness is used, the strength-elongation balance of the press-formed product can be raised to a high level by hot pressing this under predetermined conditions. In addition, when hot pressing is performed under different conditions in a plurality of regions, an impact resistant part and an energy absorbing part can be formed in a single molded product, and a high strength and elongation balance can be achieved at each part at a high level. The anti-softening property of is improved.
  • the inventors of the present invention when heating a steel plate to a predetermined temperature and then producing a press-formed product by hot press forming, show good ductility (elongation) while ensuring high strength after press forming. In order to realize a hot-press steel sheet that can provide a simple press-formed product, studies were made from various angles.
  • the chemical component composition of the steel sheet for hot pressing is strictly defined, the size of Ti-containing precipitates and the amount of precipitated Ti are controlled, the metal structure is made appropriate, and the steel sheet is subjected to predetermined conditions. It has been found that by performing hot press molding, a predetermined amount of retained austenite can be secured after press molding, and a press-molded product having increased inherent ductility (residual ductility) can be obtained, and the present invention has been completed.
  • C corresponds to an impact resistant site and an energy absorbing site in a single molded product in order to achieve a high balance between high strength and elongation when uniform properties are required in a press molded product. It is an important element for securing retained austenite when a region is required, particularly in a low strength / high ductility region. Moreover, at the time of heating by hot press molding, C concentrates to austenite, so that residual austenite can be formed after quenching. Furthermore, it contributes to an increase in the amount of martensite and raises the strength. In order to exert these effects, the C content needs to be 0.15% or more.
  • the target metal structure ferrite, bainitic ferrite, especially in low strength and high ductility parts
  • the preferable lower limit of the C content is 0.17% or more (more preferably 0.20% or more), and the more preferable upper limit is 0.45% or less (more preferably 0.40% or less).
  • Si (Si: 0.2-3%) Si exhibits the effect of forming retained austenite by suppressing martensite from tempering to form cementite and decomposition of untransformed austenite during cooling of mold quenching.
  • the Si content needs to be 0.2% or more. Further, if the Si content is excessive and exceeds 3%, ferrite transformation is promoted during cooling after hot rolling, so that TiC in the ferrite formed at that time is easily formed coarsely. Therefore, the HAZ softening preventing property cannot be obtained.
  • the preferable lower limit of the Si content is 0.5% or more (more preferably 1.0% or more), and the preferable upper limit is 2.5% or less (more preferably 2.0% or less).
  • Mn is an element effective in enhancing hardenability and suppressing the formation of structures (ferrite, pearlite, bainite, etc.) other than martensite and retained austenite during cooling of mold hardening. Further, it is an element that stabilizes austenite and contributes to an increase in the amount of retained austenite. In order to exhibit such an effect, it is necessary to contain 0.5% or more of Mn. When only the characteristics are taken into consideration, it is preferable that the Mn content is high, but the upper limit is made 3% or less because the cost of alloy addition increases. The minimum with preferable Mn content is 0.7% or more (more preferably 1.0% or more), and a preferable upper limit is 2.5% or less (more preferably 2.0% or less).
  • P 0.05% or less (excluding 0%)
  • P is an element inevitably contained in the steel, but it deteriorates ductility, so P is preferably reduced as much as possible.
  • the upper limit was made 0.05% or less (excluding 0%).
  • the upper limit with preferable P content is 0.045% or less (more preferably 0.040% or less).
  • S 0.05% or less (excluding 0%)
  • S is an element inevitably contained in steel, and deteriorates ductility. Therefore, S is preferably reduced as much as possible.
  • the upper limit was made 0.05% or less (excluding 0%).
  • the upper limit with preferable S content is 0.045% or less (more preferably 0.040% or less).
  • Al 0.01-1%)
  • Al is useful as a deoxidizing element, and also fixes solid solution N present in steel as AlN, which is useful for improving ductility.
  • the Al content needs to be 0.01% or more.
  • the preferable lower limit of the Al content is 0.02% or more (more preferably 0.03% or more), and the preferable upper limit is 0.8% or less (more preferably 0.6% or less).
  • B has an action of suppressing ferrite transformation, pearlite transformation, and bainite transformation on the high-strength portion side, so that during the cooling after heating to the two-phase region temperature (Ac 1 transformation point to Ac 3 transformation point), It is an element that prevents the formation of pearlite and bainite and contributes to securing retained austenite.
  • B In order to exert such an effect, B needs to be contained in an amount of 0.0002% or more, but the effect is saturated even if it is contained in excess of 0.01%.
  • a preferable lower limit of the B content is 0.0003% or more (more preferably 0.0005% or more), and a preferable upper limit is 0.008% or less (more preferably 0.005% or less).
  • Ti 3.4 [N] + 0.01% or more, 3.4 [N] + 0.1% or less: [N] is N content (mass%)
  • Ti fixes N and allows B to be maintained in a solid solution state, thereby exhibiting an effect of improving hardenability. In order to exert such an effect, it is important to contain 0.01% or more than the stoichiometric ratio of Ti and N (3.4 times the N content). Further, Ti added excessively to N is present in a solid solution state in the hot stamping molded product, and the precipitated compound is dispersed finely, so that the solid solution is dissolved when the hot stamping molded product is welded.
  • Strength reduction in HAZ can be suppressed by effects such as precipitation strengthening due to the formation of Ti as TiC and an increase delay of dislocation density due to the effect of preventing dislocation movement due to TiC.
  • the Ti content becomes excessive and exceeds 3.4 [N] + 0.1%, the Ti-containing precipitates formed (for example, TiN) are coarsened and the ductility of the steel sheet is lowered.
  • the more preferable lower limit of the Ti content is 3.4 [N] + 0.02% or more (more preferably 3.4 [N] + 0.05% or more), and the more preferable upper limit is 3.4 [N]. + 0.09% or less (more preferably 3.4 [N] + 0.08% or less).
  • N (N: 0.001 to 0.01%) N is an element inevitably mixed in and is preferably reduced as much as possible. However, since there is a limit to reducing it in the actual process, 0.001% was set as the lower limit. Further, when the N content is excessive, the Ti-containing precipitates formed (for example, TiN) are coarsened, and the precipitates act as a starting point for fracture and reduce the ductility of the steel sheet. It was.
  • the upper limit with more preferable N content is 0.008% or less (more preferably 0.006% or less).
  • the basic chemical components in the steel sheet for hot pressing of the present invention are as described above, and the balance is iron and inevitable impurities (for example, O, H, etc.) other than P, S, and N.
  • the steel sheet for hot pressing according to the present invention further contains at least one of the following (a) to (c) if necessary.
  • the properties of the steel sheet for hot pressing ie, press-formed product
  • the preferable range when these elements are contained and the reason for limiting the range are as follows.
  • A 0.1% or less in total of one or more selected from the group consisting of V, Nb and Zr (excluding 0%)
  • B 1% or less in total of at least one selected from the group consisting of Cu, Ni, Cr and Mo (not including 0%)
  • C 0.01% or less (excluding 0%) of at least one selected from the group consisting of Mg, Ca and REM
  • V, Nb, and Zr have the effect of forming fine carbides and making the structure fine by the pinning effect. In order to exhibit such an effect, it is preferable to contain 0.001% or more in total. However, when the content of these elements is excessive, coarse carbides are formed, and the ductility is deteriorated by becoming the starting point of fracture. For these reasons, the total content of these elements is preferably 0.1% or less. The more preferable lower limit of the content of these elements is 0.005% or more (more preferably 0.008% or more) in total, and the more preferable upper limit is 0.08% or less (more preferably 0.06%) in total. The following).
  • Cu, Ni, Cr and Mo 1% or less in total (excluding 0%)
  • Cu, Ni, Cr, and Mo suppress ferrite transformation, pearlite transformation, and bainite transformation, and thus prevent formation of ferrite, pearlite, and bainite during cooling after heating, and effectively act to secure retained austenite.
  • the more preferable lower limit of the content of these elements is 0.05% or more (more preferably 0.06% or more) in total, and the more preferable upper limit is 0.5% or less (more preferably 0.3% or less) in total. ).
  • a total of one or more selected from the group consisting of Mg, Ca and REM (rare earth elements) is 0.01% or less (excluding 0%)) Since these elements refine the inclusions, they effectively work to improve ductility. In order to exhibit these effects, it is preferable to contain 0.0001% or more in total. Considering only the characteristics, it is preferable that the content is large, but since the effect is saturated, the total content is preferably 0.01% or less.
  • the more preferable lower limit of the content of these elements is 0.0002% or more (more preferably 0.0005% or more) in total, and the more preferable upper limit is 0.005% or less (more preferably 0.003% or less) in total. ).
  • the Ti-containing precipitates and the control of the formula (1) are for preventing the softening of the HAZ, and are essentially necessary control in the molded product, but the change of these values before and after hot press molding is small. Therefore, it is necessary to already control at the stage before forming (steel plate for hot pressing).
  • a Ti-containing precipitate can be maintained in a solid solution state or a fine state during heating by hot pressing. It becomes like this.
  • the amount of precipitated Ti in the press-formed product can be controlled to a predetermined amount or less, and joint characteristics can be improved by preventing softening in the HAZ.
  • the average equivalent circle diameter of those having an equivalent circle diameter of 30 nm or less is 6 nm or less.
  • the equivalent circle diameter of the target Ti-containing precipitate is defined as 30 nm or less, except for TiN, which is coarsely formed in the melting stage and does not affect the structure change or properties thereafter. This is because it is necessary to control the Ti-containing precipitates.
  • the size (average equivalent circle diameter) of the Ti-containing precipitate is preferably 5 nm or less, and more preferably 3 nm or less.
  • the Ti-containing precipitates that are the subject of the present invention include TiC and TiN as well as precipitates containing Ti such as TiVC, TiNbC, TiVCN, and TiNbCN.
  • the average equivalent circle diameter of Ti-containing precipitates in a press-formed product is specified to be 10 nm or less, whereas it is specified to be 6 nm or less before forming (hot-press steel plate). .
  • the reason is that Ti is present in a fine precipitate or a solid solution state in the steel plate, but when heating for about 15 minutes or more near 800 ° C., the Ti-containing precipitate is slightly coarsened. Rather than the molded product, the size of the precipitate is defined larger.
  • the average equivalent circle diameter of the Ti-containing precipitate is required to be 10 nm or less, and in order to realize the precipitation state with a hot stamped product, It is necessary that the average equivalent circle diameter of fine precipitates of 30 ⁇ m or less is 6 nm or less at the stage, and most of Ti is present in a solid solution state.
  • the amount of Ti present as precipitates other than TiN is the remaining amount of 0.1% after subtracting the Ti forming TiN out of the total Ti.
  • the amount needs to be less than 5 times (that is, 0.5 ⁇ [total Ti amount (mass%) ⁇ 3.4 [N]]) (requirement (B) above).
  • the amount of precipitated Ti (mass%)-3.4 [N] is preferably 0.4 ⁇ [total Ti amount (mass%)-3.4 [N]] or less, more preferably 0.3 ⁇ [ The total Ti amount (% by mass) is -3.4 [N] or less.
  • the ferrite fraction in the hot-press steel sheet needs to be 30 area% or more (requirement (C) above).
  • the ferrite fraction is preferably 50 area% or more, more preferably 70 area% or more.
  • the balance of the metal structure is not particularly limited, and examples thereof include at least one of pearlite, bainite, martensite, and retained austenite.
  • a slab obtained by melting a steel material having the above chemical composition is heated at a temperature of 1100 ° C. or higher (preferably 1150 ° C. or higher), Hot rolling is performed at 1300 ° C. or lower (preferably 1250 ° C. or lower), and the finish rolling temperature is 850 ° C. or higher (preferably 900 ° C. or higher), or 1050 ° C. or lower (preferably 1000 ° C. or lower). (Preferably 625 ° C. or less) is cooled (rapidly cooled) at an average cooling rate of 20 ° C./second or more (preferably 30 ° C./second or more), and 620 ° C.
  • 580 ° C. is 10 ° C./second or less (preferably 5 ° C. After cooling at an average cooling rate of 10 ° C./second or higher, then 350 ° C. or higher (preferably 380 ° C. or higher), 450 ° C. or lower (preferably 4 0 °C should be as winding below).
  • the steel sheet for hot pressing having the chemical composition, the metal structure and the Ti precipitation state as described above may be used for the production of the hot press as it is, and the reduction ratio after pickling: 60% or less (preferably 40% The following may be applied to the production of a hot press after cold rolling.
  • the steel sheet for hot pressing of the present invention may have a microstructure when the hot-rolled material is heat-treated in a continuous annealing furnace or a continuous hot dip galvanizing line. In short, as long as the required characteristics such as the metal structure and the Ti precipitation state are satisfied, it is included in the steel sheet for hot pressing of the present invention.
  • a steel sheet containing a predetermined amount of ferrite it is necessary to control the heating temperature within a predetermined range in order to partially transform the ferrite into austenite while partially retaining the ferrite.
  • the heating temperature of the steel sheet is less than the Ac 1 transformation point + 20 ° C., a sufficient amount of austenite cannot be obtained during heating, and a predetermined amount of retained austenite cannot be secured in the final structure (structure of the molded product). If the heating temperature of the steel sheet exceeds the Ac 3 transformation point of ⁇ 20 ° C., the amount of transformation to austenite increases too much during heating, and a predetermined amount of ferrite cannot be secured in the final structure (structure of the molded product).
  • the average cooling rate and the cooling end temperature during and after molding are appropriately controlled. There is a need. From such a viewpoint, the average cooling rate during molding must be 20 ° C./second or more, and the cooling end temperature must be 100 ° C. or lower than the bainite transformation start temperature Bs.
  • the average cooling rate during molding is preferably 30 ° C./second or more (more preferably 40 ° C./second or more). By making the cooling end temperature 100 ° C.
  • the austenite existing during heating is transformed into bainite or martensite while preventing the formation of a structure such as ferrite or pearlite.
  • a predetermined amount of retained austenite is secured by allowing fine austenite to remain between bainite and martensite lath while securing martensite.
  • the cooling end temperature is higher than the temperature lower by 100 ° C. than the bainite transformation start temperature Bs or the average cooling rate is less than 20 ° C./second, a structure such as ferrite or pearlite is formed, and a predetermined amount of retained austenite is secured. This is not possible, and the elongation (ductility) of the molded product is deteriorated.
  • the cooling end temperature is not particularly limited as long as it is 100 ° C. or lower than Bs, and may be, for example, martensitic transformation start temperature Ms or lower.
  • control of the average cooling rate is basically unnecessary when the temperature is lower than the bainite transformation start temperature Bs by 100 ° C. or less, for example, at an average cooling rate of 1 ° C./second or more and 100 ° C./second or less to room temperature. It may be cooled.
  • Control of the average cooling rate during molding and after molding is completed by controlling (a) the temperature of the molding die (cooling medium shown in FIG. 1) and (b) controlling the thermal conductivity of the die. It can be achieved by such means.
  • a press-molded product single region molded product manufactured by hot pressing as described above
  • the metal structure is retained austenite: 3 to 20 area%, ferrite: 30 to 80 area%, bainitic ferrite: 30 Less than area% (excluding 0 area%), martensite: 31 area% or less (excluding 0 area%), and a high level and uniform balance between high strength and elongation in the molded product It can be achieved.
  • the reason for setting the range of each requirement (basic structure) in such a hot press-formed product is as follows.
  • Residual austenite has the effect of increasing the work hardening rate (transformation-induced plasticity) and improving the ductility of the molded product by transforming into martensite during plastic deformation.
  • the retained austenite fraction needs to be 3 area% or more.
  • the higher the retained austenite fraction the better.
  • the retained austenite that can be secured is limited, and the upper limit is about 20 area%.
  • the preferable lower limit of retained austenite is 5 area% or more (more preferably 7 area% or more).
  • the ductility (elongation) of a press-formed product can be increased by making the main structure fine and highly ductile ferrite. From this point of view, the ferrite fraction is 30% by area or more. However, if this fraction exceeds 80 area%, the strength of the molded product cannot be ensured.
  • a preferred lower limit of the ferrite fraction is 35 area% or more (more preferably 40 area% or more), and a preferred upper limit is 75 area% or less (more preferably 70 area% or less).
  • Bainitic ferrite is an effective structure for improving the strength of a molded product, but it is a structure that is slightly poor in ductility. From such a viewpoint, the fraction of bainitic ferrite is less than 30 area%. A preferable upper limit of the fraction of bainitic ferrite is 25 area% or less (more preferably 20 area% or less).
  • Martensite (an as-quenched martensite) is an effective structure for improving the strength of a molded product, but is a structure having poor ductility, and therefore, when present in a large amount, it deteriorates elongation. From such a viewpoint, the martensite fraction is 31 area% or less. A preferred upper limit of the martensite fraction is 25 area% or less (more preferably 20 area% or less).
  • pearlite may be included as the remaining structure.
  • these structures have a lower contribution to strength and ductility than other structures, and it is preferable not to basically contain them. (It may be 0 area%).
  • the equivalent of the average circle having an equivalent circle diameter of 30 nm or less is 10 nm or less.
  • the average equivalent circle diameter of the Ti-containing precipitate is preferably 8 nm or less, and more preferably 6 nm or less.
  • the amount of Ti present as precipitates other than TiN is the remainder after subtracting Ti that forms TiN out of all Ti.
  • the Ti content is less than 0.5 times that of Ti (that is, less than 0.5 ⁇ [total Ti amount (%) ⁇ 3.4 [N]]).
  • the deposited Ti amount-3.4 [N] is preferably 0.4 ⁇ [total Ti amount (mass%) ⁇ 3.4 [N]] or less, more preferably 0.3 ⁇ [total Ti amount ( % By mass) -3.4 [N]] or less.
  • the properties such as strength and elongation of the press-formed product can be controlled by appropriately adjusting the press forming conditions (heating temperature and cooling rate) and high ductility. (Residual ductility) press-molded products can be obtained, so it can be applied to parts that have been difficult to apply with conventional press-molded products (for example, energy absorbing members). Useful.
  • the heating temperature and the conditions of each region at the time of molding are appropriately controlled.
  • a press-formed product that exhibits a strength-ductility balance corresponding to each region hereinafter sometimes referred to as a multi-region molded product
  • the heating region of the steel plate is divided into at least two regions, one of which is hereinafter referred to as the first region. Is heated to a temperature not lower than Ac 3 transformation point and not higher than 950 ° C., and the other region (hereinafter referred to as second region) is not lower than Ac 1 transformation point + 20 ° C. and temperature not higher than Ac 3 transformation point ⁇ 20 ° C. Then, press molding is started for both the first and second regions, and during molding and after completion of molding, both the first and second regions have a temperature of 20 ° C./second or more in the mold. What is necessary is just to cool to the temperature below the martensitic transformation start temperature Ms, ensuring an average cooling rate.
  • the heating region of the steel sheet is divided into at least two regions (high-strength side region and low-strength side region), and the manufacturing conditions are controlled according to each region, whereby the strength-ductility balance corresponding to each region is obtained.
  • a press-formed product exhibiting the above can be obtained.
  • the second region corresponds to the low-strength side region
  • the manufacturing conditions, structure, and characteristics in this region are basically the same as those of the single-region molded product described above.
  • manufacturing conditions for forming the other first region corresponding to the high-strength side region
  • the heating temperature of the steel sheet is preferably Ac 3 transformation point + 50 ° C. or higher and 930 ° C. or lower.
  • the average cooling rate and the cooling end temperature during and after molding are appropriately controlled. There is a need. From this point of view, the average cooling rate during molding needs to be 20 ° C./second or more, and the cooling end temperature needs to be lower than the martensite transformation start temperature (Ms point).
  • the average cooling rate during molding is preferably 30 ° C./second or more (more preferably 40 ° C./second or more).
  • the cooling end temperature is specifically 400 ° C. or lower, preferably 300 ° C. or lower.
  • the metal structure and precipitates are different between the first region and the second region.
  • the metal structures are retained austenite: 3 to 20 area% (the effect of retained austenite is the same as described above), and martensite: 80 area% or more.
  • the same metal structure and Ti state average equivalent circle diameter of Ti-containing precipitates, amount of precipitated Ti (mass%) -3.4 [N], etc.) as the single region molded product are satisfied. .
  • the area fraction of martensite needs to be 80 area% or more.
  • the fraction of martensite is preferably 85 area% or more (more preferably 90 area% or more).
  • the remaining structure in the first region may partially include ferrite, pearlite, bainite, and the like.
  • Example 1 Steel materials (steel Nos. 1-16, 18-32) having the chemical composition shown in Tables 1 and 2 below are vacuum-melted to form experimental slabs, followed by hot rolling to obtain steel plates, and then The process which cooled and simulated winding was performed (plate
  • the winding simulation processing method after cooling to the winding temperature, the sample was placed in a furnace heated to the winding temperature, held for 30 minutes, and then cooled in the furnace. The steel sheet manufacturing conditions at this time are shown in Tables 3 and 4 below.
  • Treatment (1) After cold-rolling a hot-rolled steel sheet (sheet thickness: 1.6 mm), simulating continuous annealing with a heat treatment simulator, heating to 800 ° C., holding for 90 seconds, and average cooling at 20 ° C./second Cooled to 500 ° C. at a rate and held for 300 seconds.
  • the obtained steel plate (press forming steel plate) was analyzed for the precipitation state of Ti and the observation of the metal structure (fraction of each structure) in the following manner. Moreover, the tensile strength (TS) of each steel plate was measured by the method mentioned later. The results are shown in Table 5 below together with a calculated value of 0.5 ⁇ [total Ti amount (mass%) ⁇ 3.4 [N]] [displayed as 0.5 ⁇ [total Ti amount-3.4 [N]]]. , 6.
  • the amount of precipitated Ti (mass%)-3.4 [N] (the amount of Ti present as a precipitate) was subjected to extraction residue analysis using a mesh having a mesh diameter of 0.1 ⁇ m (in the extraction process, Precipitates aggregate and fine precipitates can be measured), and the amount of precipitated Ti (mass%)-3.4 [N] (in Tables 5 and 6, indicated as precipitated Ti amount-3.4 [N]) is obtained. It was. When the Ti-containing precipitate partially contains V or Nb, the content of these precipitates was also measured.
  • the Ti precipitation state was analyzed by the method described above.
  • the martensite (as-quenched martensite) fraction was determined by X-ray diffraction from the area ratio of the martensite and retained austenite as it was quenched by repeller corrosion of the steel sheet.
  • the martensite fraction was calculated by subtracting the residual austenite fraction.
  • Tables 8 and 9 The observation results of the metal structure (Ti precipitation state, fraction of each structure, amount of precipitated Ti-3.4 [N]) are shown in Tables 8 and 9 below.
  • Table 10 shows the mechanical properties (tensile strength TS, elongation EL, TS ⁇ EL, and hardness reduction amount ⁇ Hv) of the molded product.
  • the value of the precipitated Ti amount-3.4 [N] in the formed product is slightly different from the value of the precipitated Ti amount-3.4 [N] in the press-formed steel sheet, but this is a measurement error.
  • Steel No. Those of 3, 7 to 9, 12 to 14, 18, and 22 are comparative examples that do not satisfy any of the requirements defined in the present invention, and any of the characteristics is deteriorated. That is, Steel No. No. 3 uses a steel sheet for press forming with a low Si content, and the retained austenite fraction in the press-formed product is not ensured and elongation is not achieved, so that the strength-elongation balance deteriorates. ing. Steel No. No. 7 has a low finish rolling temperature at the time of manufacturing the steel sheet, the Ti-containing precipitates in the press forming steel sheet become coarse, and does not satisfy the relationship of formula (1) at any stage of the press forming steel sheet or the press formed product. The anti-softening property is deteriorated.
  • Steel No. No. 8 has a high cooling rate of 620 ° C. to 580 ° C. at the time of manufacturing the steel sheet, the ferrite transformation does not proceed sufficiently, the ferrite fraction in the press forming steel sheet cannot be secured, and the strength becomes high. It is expected that molding and processing before press molding will be difficult.
  • Steel No. In No. 9 the coiling temperature at the time of manufacturing the steel sheet is high, and the Ti-containing precipitates in the steel sheet for press forming are coarsened. When press forming using such a steel sheet, the forming conditions are appropriate and the strength- Even if the ductility balance is good, the anti-softening property is deteriorated.
  • Steel No. No. 14 has a high cooling end temperature during press molding, pearlite is generated, retained austenite cannot be secured, strength and elongation are lowered, and strength-elongation balance (TS ⁇ EL) is deteriorated.
  • Steel No. No. 18 uses a steel sheet for press forming with an excessive C content, the ferrite fraction of the steel sheet cannot be secured, the ferrite fraction in the press-formed product cannot be secured, and only a low elongation EL is obtained. The strength-elongation balance (TS ⁇ EL) is also deteriorated.
  • Example 2 Steel materials (steel Nos. 33 to 37) having the chemical composition shown in Table 11 below were melted in vacuum to form experimental slabs, followed by hot rolling, followed by cooling and winding (sheet thickness) : 3.0 mm). The steel plate production conditions at this time are shown in Table 12 below.
  • each steel sheet (3.0mm t ⁇ 150mm ⁇ 200mm) was heated to a predetermined temperature in a heating furnace, performing a press-forming and cooling process in a mold of hat-shaped (FIG. 1), and a molded article .
  • the steel sheet is placed in an infrared furnace, and the portion (the steel plate portion corresponding to the first region) to be strengthened is directly irradiated with infrared rays so that the portion can be heated at a high temperature.
  • the steel plate portion corresponding to the region of (1) was covered with a cover so as to block a part of infrared rays so that it could be heated at a low temperature, thereby giving a heating temperature difference. Therefore, the molded product has regions having different strengths within a single part.
  • Table 14 shows the press molding conditions (heating temperature, average cooling rate, rapid cooling end temperature in each region during press molding).
  • Table 15 shows the observation results of metal structures (fraction of each structure) and the analysis results of the precipitation state of Ti.
  • the mechanical properties (tensile strength TS, elongation EL, TS ⁇ EL, and hardness reduction amount ⁇ Hv) of the press-formed product are shown in Table 16 below.
  • the tensile strength (TS) on the high strength side is 1470 MPa or higher
  • the elongation (EL) satisfies 8% or higher
  • the strength-elongation balance (TS ⁇ EL) is 14000 (MPa ⁇ %) or higher.
  • Steel No. Nos. 33 to 36 are examples that satisfy the requirements defined in the present invention, and it can be seen that press-formed products having a good strength-ductility balance in each region are obtained.
  • Steel No. In No. 37 the heating temperature at the time of press molding is low, the martensite fraction on the high strength side is insufficient, and the strength on the high strength side is reduced (the strength difference from the low strength side is Less than 300 MPa).
  • the average equivalent circle diameter of those having an equivalent circle diameter of 30 nm or less is 6 nm or less, and the amount of precipitated Ti in the steel And the total Ti content satisfy a predetermined relationship, and the metal structure has a ferrite fraction of 30% by area or more, so that molding and processing can be easily performed before hot pressing, and in the molded product.
  • a press-molded product that can achieve a high level of balance between strength and elongation can be obtained, and the area corresponding to the impact-resistant and energy-absorbing sites in a single molded product. Is required, it is possible to achieve a high level of balance between high strength and elongation according to each region, and hot press useful for obtaining a press-molded product with good softening prevention properties in HAZ. Steel sheet can be realized.

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Abstract

　La présente invention concerne une plaque d'acier pressée à chaud utile pour obtenir un article moulé à la presse ayant d'excellentes caractéristiques anti-ramollissement dans des zones thermiquement affectées (HAZ) tout en obtenant un article moulé à la presse qui peut atteindre un niveau élevé d'équilibre entre une résistance élevée et une aptitude à l'étirage si des caractéristiques uniformes dans l'article moulé sont requises, et un niveau élevé d'équilibre entre une résistance élevée et une aptitude à l'étirage dans des régions respectives si des régions correspondant à des parties résistantes aux chocs et des parties d'absorption d'énergie sont requises dans un article moulé ; le moulage et le traitement avant le pressage à chaud étant facilités par la plaque d'acier pressée à chaud ayant une composition chimique prescrite, ayant un diamètre circulaire équivalent de dépôts contenant Ti inclus dans la plaque d'acier étant de 30 nm ou moins, le diamètre circulaire équivalent moyen des dépôts contenant Ti étant de 6 nm ou moins, la quantité de Ti déposée et la quantité totale de Ti dans l'acier satisfaisant à une relation prescrite, et ayant une structure métallique avec une proportion de ferrite de 30 % en aire ou moins.
PCT/JP2013/074426 2013-09-10 2013-09-10 Plaque d'acier pressée à chaud, article moulé à la presse, et procédé de fabrication d'article moulé à la presse WO2015037060A1 (fr)

Priority Applications (9)

Application Number Priority Date Filing Date Title
CA3014626A CA3014626A1 (fr) 2013-09-10 2013-09-10 Plaque d'acier pressee a chaud, article moule a la presse, et procede de fabrication d'article moule a la presse
CA2923583A CA2923583A1 (fr) 2013-09-10 2013-09-10 Plaque d'acier pressee a chaud, article moule a la presse, et procede de fabrication d'article moule a la presse
MX2016003260A MX2016003260A (es) 2013-09-10 2013-09-10 Placa de acero de prensado en caliente, articulo moldeado a presion, y metodo para fabricar articulo moldeado a presion.
KR1020167006201A KR101827187B1 (ko) 2013-09-10 2013-09-10 열간 프레스용 강판 및 프레스 성형품, 및 프레스 성형품의 제조 방법
EP13893228.0A EP3045553A4 (fr) 2013-09-10 2013-09-10 Plaque d'acier pressée à chaud, article moulé à la presse, et procédé de fabrication d'article moulé à la presse
CN201380079439.1A CN105518170A (zh) 2013-09-10 2013-09-10 热压用钢板和冲压成形品、以及冲压成形品的制造方法
PCT/JP2013/074426 WO2015037060A1 (fr) 2013-09-10 2013-09-10 Plaque d'acier pressée à chaud, article moulé à la presse, et procédé de fabrication d'article moulé à la presse
US14/917,823 US20160222482A1 (en) 2013-09-10 2013-09-10 Hot-pressing steel plate, press-molded article, and method for manufacturing press-molded article
RU2016111914A RU2625357C1 (ru) 2013-09-10 2013-09-10 Горячештампованная толстолистовая сталь, формованное штампованием изделие и способ изготовления формованного штампованием изделия

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EP3485996B1 (fr) * 2016-07-13 2022-06-01 Nippon Steel Corporation Produit embouti à chaud, élément structural l'utilisant et procédé de fabrication d'un produit embouti à chaud

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EP3045553A1 (fr) 2016-07-20
RU2625357C1 (ru) 2017-07-13
CN105518170A (zh) 2016-04-20
KR20160042968A (ko) 2016-04-20
EP3045553A4 (fr) 2017-03-22
US20160222482A1 (en) 2016-08-04
MX2016003260A (es) 2016-06-07
CA3014626A1 (fr) 2015-03-19
CA2923583A1 (fr) 2015-03-19

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