WO2014156790A1 - プレス成形品およびその製造方法 - Google Patents
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- WO2014156790A1 WO2014156790A1 PCT/JP2014/057204 JP2014057204W WO2014156790A1 WO 2014156790 A1 WO2014156790 A1 WO 2014156790A1 JP 2014057204 W JP2014057204 W JP 2014057204W WO 2014156790 A1 WO2014156790 A1 WO 2014156790A1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B15/00—Layered products comprising a layer of metal
- B32B15/01—Layered products comprising a layer of metal all layers being exclusively metallic
- B32B15/013—Layered products comprising a layer of metal all layers being exclusively metallic one layer being formed of an iron alloy or steel, another layer being formed of a metal other than iron or aluminium
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- 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
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- 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
- B21D24/00—Special deep-drawing arrangements in, or in connection with, presses
- B21D24/04—Blank holders; Mounting means therefor
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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
- 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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- 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
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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
- C21D9/0068—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for particular articles not mentioned below
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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
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C18/00—Alloys based on zinc
- C22C18/04—Alloys based on zinc with aluminium as the next major constituent
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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
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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
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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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
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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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
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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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
- C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
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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
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
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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
- C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
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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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
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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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
- C23C2/06—Zinc or cadmium or alloys based thereon
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/26—After-treatment
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/26—After-treatment
- C23C2/261—After-treatment in a gas atmosphere, e.g. inert or reducing atmosphere
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/26—After-treatment
- C23C2/28—Thermal after-treatment, e.g. treatment in oil bath
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/26—After-treatment
- C23C2/28—Thermal after-treatment, e.g. treatment in oil bath
- C23C2/29—Cooling or quenching
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/34—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the shape of the material to be treated
- C23C2/36—Elongated material
- C23C2/40—Plates; Strips
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2605/00—Vehicles
- B32B2605/08—Cars
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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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
Definitions
- the present invention relates to a press-formed product that requires strength and corrosion resistance as used for a structural member of an automobile part and a manufacturing method thereof, and more particularly, after heating a galvanized steel sheet or an alloyed hot-dip galvanized steel sheet,
- the present invention relates to a press-molded product that obtains a predetermined strength by quenching at the same time as shape imparting, and a method for producing such a press-molded product.
- hot stamping a so-called hot press molding method in which the strength of the molded product is ensured by quenching simultaneously with molding.
- hot stamp is spreading as a construction method for manufacturing a part (press-molded product) that requires a high strength of 1470 MPa or more in particular.
- FIG. 1 is a schematic explanatory view showing a mold configuration for carrying out hot stamping as described above, in which 1 is a punch, 2 is a die, 3 is a blank holder, 4 is a steel plate (blank), and BHF is The wrinkle pressing force, rp is the punch shoulder radius, rd is the die shoulder radius, and CL is the 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 made to have a single-phase temperature equal to or higher than the two-phase region temperature (Ac1 transformation point to Ac3 transformation point) or Ac3 transformation point. Molding is started in a state of being softened by heating to a zone temperature. 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. While shrinking, it is formed into a shape corresponding to the outer shape of the punch 1.
- liquid metal embrittlement (hereinafter referred to as “ LME ” may cause cracks during press molding, resulting in a problem that impact resistance and fatigue strength as a part (press-molded product) are reduced.
- Patent Document 1 discloses that a high temperature holding time before press molding is made relatively long (for example, 300 seconds or more).
- a method has been proposed in which alloying of the plating layer is promoted and the Fe concentration in the plating layer is increased to suppress the occurrence of cracks during press forming.
- this method has a drawback in that it requires heating for a long time in the hot stamping process, which impairs productivity.
- the method of the present invention that has achieved the above object is a method for producing a press-formed product by forming a galvanized steel sheet or an alloyed hot-dip galvanized steel sheet by a hot press forming method, and heating the steel sheet After the holding, forming is started at a temperature of 680 ° C. or higher and 750 ° C. or lower while liquid zinc is present on the steel plate surface, and the strain rate at the plastic deformation portion of the steel plate is set to 0.5 second ⁇ 1 or lower. Molding is performed.
- the heating and holding of the steel sheet is preferably performed at a temperature of 880 ° C. or more and 920 ° C. or less for 10 seconds to 4 minutes.
- the plate thickness of the steel plate is t (mm), the bending radius (inner diameter) of the plastic deformation portion.
- R is (mm)
- a configuration in which the plastic deformation portion is formed over [t / (R + t / 2)] seconds or more can be mentioned.
- a press-molded product manufactured by the method as described above is also included.
- the heating conditions before forming and the strain rate at the plastic deformation portion of the steel sheet during forming are appropriately controlled.
- the heating time before molding was shortened, it was possible to produce a press-molded product exhibiting good characteristics while avoiding the occurrence of LME cracks with high productivity.
- FIG. 1 is a schematic explanatory view showing a mold configuration for carrying out hot press molding.
- FIG. 2 is a schematic explanatory view showing a mechanism in a mold when the present invention is carried out.
- FIG. 3 is a diagram for explaining a cross section of the R portion of the steel plate that vertically bisects the R ridge line.
- the inventors of the present invention after heating a galvanized steel sheet or an alloyed hot dip galvanized steel sheet to a predetermined temperature and then producing a press-formed product by hot press forming, press forming In order to produce a press-molded product exhibiting good characteristics while avoiding the occurrence of LME cracks with good productivity, investigations were made from various angles.
- LME cracks are generated when press forming is performed in a state where the base steel sheet is embrittled by molten liquid zinc.
- a steel sheet with liquid zinc adhered thereto is press-molded, liquid zinc infiltrates into the crystal grain boundaries, and the yield strength of the crystal grain boundaries is lost, so it is considered that cracks occur.
- the galvanized layer is liquefied, and a reaction in which a solid alloy phase of Fe / Zn is generated at the interface with the steel sheet proceeds, and the Fe concentration in the plated layer increases.
- Patent Document 1 It is known that when a certain time or more elapses after heating, liquid zinc in the plating layer is almost lost, and thus LME cracks are not generated even if press molding is performed thereafter (Patent Document 1). However, since it is necessary to hold
- the present inventors examined the influence of various process conditions. As a result, forming was performed such that the strain rate at the plastic deformation portion of the steel sheet during forming was 0.5 sec- 1 or less. Thus, it was found that cracks due to LME can be suppressed even if the time (holding time) held in the heating step before press molding is relatively short and within 4 minutes.
- the strain rate at this time is preferably 0.4 sec- 1 or less (more preferably 0.3 sec- 1 or less). However, if the strain rate is made too slow, the productivity will be lowered, so it is preferable to set it to 0.1 second- 1 or more.
- the holding time may be 4 minutes or less (preferably 3 minutes or less), but from the viewpoint of austenitizing the entire steel structure, it is 10 seconds or more (preferably 30 seconds or more, more preferably 1 minute or more). It is preferable to do.
- the thickness of the steel plate is t ( mm), where the bending radius (inner diameter) of the plastic deformation part is R (mm), the plastic deformation part is formed over t / (R + t / 2) seconds or more.
- FIG. 2 is a schematic explanatory view showing a mechanism in a mold when the present invention is carried out.
- the mold configuration shown in FIG. 2 is upside down with respect to the mold configuration shown in FIG. 1 for convenience of explanation.
- the bending radius (inner diameter) R (mm) of the plastic deformation portion corresponds to the die shoulder radius rd shown in FIG.
- the punch speed V (mm / second) means that the molding satisfies the relationship of the following formula (2). From these relationships, it is understood that the plastic deformation portion may be formed in [t / (R + t / 2)] seconds or more.
- the plate thickness is 1.4 mm and the bending radius (inner diameter) is 5 mm or 10 mm, it corresponds to the molding speed over 0.25 seconds or more or 0.13 seconds or more, respectively.
- the plate thickness is 0.8 mm and the bending radius (inner diameter) is 5 mm or 10 mm, it corresponds to the molding speed of 0.15 seconds or more and 0.08 seconds or more, respectively.
- the range for press forming at the strain rate as described above may be at least the plastic deformation portion (region shown in FIG. 2), but the other steel plate regions may be formed at the same strain rate. However, in regions other than the plastically deformed portion, LME cracks are unlikely to occur, so press molding may be performed with a strain rate higher than 0.5 sec- 1 .
- a galvanized steel sheet or an alloyed hot-dip galvanized steel sheet that has been plated on the surface of the base steel sheet (sometimes collectively referred to as “surface-treated steel sheet”) is pressed using a mold.
- the surface-treated steel sheet is first heated and held.
- the heating at this time is preferably a temperature of 880 ° C. or more and 920 ° C. or less.
- the heating temperature is preferably at least 880 ° C. or higher. When the heating temperature is less than 880 ° C., an appropriate amount of austenite cannot be obtained during heating, and good moldability cannot be ensured.
- heating temperature exceeds 920 degreeC, since the zinc in the plating layer of a surface-treated steel plate will boil and evaporate and corrosion resistance will deteriorate, it is unpreferable. Moreover, the more preferable minimum of heating temperature is 900 degreeC or more (temperature which makes all austenite), and a more preferable upper limit is 910 degreeC or less.
- the heating temperature in the present invention is a value measured by the surface temperature of the steel sheet (the same applies to the following temperatures).
- the holding time in the above temperature range may be 4 minutes or less (preferably 3 minutes or less). That is, even if this holding time is 4 minutes or less, cracks due to LME can be suppressed in subsequent press molding. However, if this holding time is too short, an appropriate amount of austenite cannot be obtained during heating, and good moldability cannot be ensured, so at least 10 seconds (preferably 30 seconds or more, more preferably 1 minute or more). It is preferable to do.
- the press molding start temperature needs to be 750 ° C. or lower.
- the productivity of the press production process will deteriorate, and in order to avoid uneven material properties after pressing due to uneven cooling, the lower limit is set to 680 ° C or higher.
- the lower limit is set to 680 ° C or higher.
- n value work hardening coefficient
- the average cooling rate at the time of cooling preferably secures an average cooling rate of 20 ° C./second or more in order to make the plating layer as solid as possible. More preferably, it is 30 ° C./second or more. However, even if the cooling stop temperature in this cooling (that is, press molding start temperature) is too low, it is necessary to set the temperature to 680 ° C. or higher even from the viewpoint that good press moldability cannot be secured. Preferably, it is 700 degreeC or more.
- the surface-treated steel sheet used in the present invention is a galvanized steel sheet or an alloyed hot dip galvanized steel sheet, but the chemical composition of a normal steel as a high-strength steel sheet is the steel type of the steel sheet (base steel sheet) that is the material of these surface-treated steel sheets. (See Table 1 in Examples below).
- the hot press molding the purpose of molding a part is mainly to increase the strength, and the strength is ensured by quenching in the process of cooling with a mold. For this reason, in general, a steel sheet to which elements that improve hardenability such as B and Mn are added in addition to C is used.
- a hot-rolled steel sheet or a cold-rolled steel sheet obtained by cold rolling a hot-rolled steel sheet can be used.
- the galvanized steel sheet used in the present invention can be obtained by galvanizing a hot-rolled steel sheet or a cold-rolled steel sheet. Sufficient corrosion resistance can be obtained by setting the desired coating amount of the galvanized layer to about 30 to 200 g / m 2 per side.
- Examples of the plating method include hot dipping and electroplating.
- An alloyed galvanized steel sheet (usually alloyed hot dip galvanized) in which the plating layer and iron in the base steel sheet are alloyed by holding at a predetermined temperature (470 ° C. to 580 ° C.) for 1 to 10 minutes after plating. Steel plate), which can also be used.
- a steel material having the chemical composition (steel types A to F) shown in Table 1 below was melted into a slab and hot-rolled to obtain a hot-rolled steel sheet having a thickness of 3.2 mm. This was cold-rolled to produce a cold-rolled steel sheet having a thickness of 0.8 mm or 1.4 mm. These steel sheets were galvanized to give galvanized steel sheets. At this time, the galvanization process was performed with the batch type atmosphere control annealing plating apparatus. Moreover, about some steel plates, the alloying process was performed and the alloyed galvanized steel plate was produced.
- an experimental furnace capable of controlling the atmosphere equipped with a heating / cooling mechanism and a crucible serving as a galvanizing bath, and capable of performing plating treatment and alloying treatment in an integrated process was used.
- the plating treatment conditions were immersed in a 460 ° C. Zn bath (Al: containing 0.13%) for 3 seconds.
- the alloying treatment was performed by holding at 550 ° C. for 20 seconds in an atmosphere of 5% H 2 —N 2 (dew point ⁇ 45 ° C.), and then cooled by blowing Ar gas.
- the average cooling rate at this time is 15 ° C./second.
- the coating amount of the galvanized steel sheet and the alloyed galvanized steel sheet was evaluated by cross-sectional SEM (scanning electron microscope) observation and Fe concentration measurement during plating.
- the zinc plating on one side of the test piece was polished and removed, and the temperature was controlled by a thermocouple installed on the side of the plating removed.
- the heating method induction heating or current heating can be considered.
- the parallel part of the test piece was heated by current heating while induction heating the vicinity of the gripping part of the test piece.
- the temperature history is from room temperature to a temperature T1 (about 900 ° C.), held for a predetermined time t1 and then cooled to a processing temperature T2, up to a predetermined target strain amount with liquid zinc remaining on the specimen surface.
- Processing was performed at a constant strain rate (second ⁇ 1 ). During heating and processing, it was performed in an air atmosphere. Only the cooling process was performed by cooling with Ar gas. In addition, liquid zinc remained on the surface of the test piece at the time of the test. In the cross-sectional SEM (scanning electron microscope) observation of “measurement of the maximum crack depth” performed after the test, a part of the plating layer was whitened. This was confirmed by the fact that a visible zinc layer remained.
- the actual value of the amount of strain was obtained by previously marking a standard line with a distance of 20 mm between the grades on the back surface (side from which the plating was removed) of the test piece, and measuring the elongation (%) of the distance between the grades with the amount of logarithmic strain.
- plate thickness, plating adhesion, presence / absence of alloying treatment, press molding conditions [heating temperature, heating holding time, average cooling rate before molding, molding start temperature), strain amount (target, actual results), strain rate (Aim, actual results) and molding time] are shown in Tables 2 to 4 below.
- Test No. 1 to 3 5 to 7, 10 to 12, 14 to 16, 19, 22, 24, 26, 28, 30, 32, 33, 35 to 37, 39, 40, 42, 43, 45, 46, 48, No. 49 is an example that satisfies the requirements defined in the present invention, and it is understood that the occurrence of LME cracks is suppressed and a good hot press-formed product is obtained.
- the molding times for these examples all satisfy the condition of [t / (R + t / 2)] seconds or more.
- test no. 4,8,9,13,17,18,20,21,23,25,27,29,31,34,38,41,44,47 Since the press molding is performed under a condition where the strain rate is large, the maximum crack depth is large.
- the present invention is useful as a method of manufacturing a structural member of an automobile part such as a side member, a side sill, a cross member, or a pillar lower part by press forming a galvanized steel sheet or an alloyed hot-dip galvanized steel sheet.
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Abstract
Description
W=t/{2(R+t/2)}/Δt=V×t/{2(R+t)×(R+t/2)}…(1)
V≦{(R+t)×(R+t/2)}/t …(2)
試験片の裏面にハット型成形した鋼板のR部について、Rの稜線を垂直二等分する断面(図3参照)で切断し、樹脂埋め研磨試料を作製した。この断面をSEMにて観察した。めっき層よりも下側(地鋼板に亀裂が進展している箇所)において、R部で進展深さが最大の亀裂の亀裂深さを測定した。各試験条件で、加工開始から歪み速度Wと最大亀裂深さの対応を確認した。
本出願は、2013年3月26日出願の日本特許出願(特願2013-065233)に基づくものであり、その内容はここに参照として取り込まれる。
2 ダイ
3 ブランクホルダー
4 鋼板(ブランク)
Claims (4)
- 亜鉛めっき鋼板または合金化溶融亜鉛めっき鋼板を、熱間プレス成形法によって成形してプレス成形品を製造する方法であって、前記鋼板を加熱・保持した後、鋼板表面に液体亜鉛が存在する状態のまま680℃以上、750℃以下の温度で成形を開始し、前記鋼板における塑性変形部での歪み速度を0.5秒-1以下として成形を行うことを特徴とするプレス成形品の製造方法。
- 前記鋼板の加熱・保持は、880℃以上、920℃以下の温度で10秒~4分間で行う請求項1に記載の製造方法。
- 前記鋼板の板厚をt(mm)、塑性変形部の曲げ半径(内径)をR(mm)としたとき、塑性変形部の成形を[t/(R+t/2)]秒以上で行う請求項1または2に記載の製造方法。
- 請求項1~3のいずれかに記載の方法によって得られたプレス成形品。
Priority Applications (4)
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EP14775588.8A EP2979771A4 (en) | 2013-03-26 | 2014-03-17 | PRESS MOLDED ARTICLE AND METHOD FOR MANUFACTURING THE SAME |
KR1020157026230A KR101719446B1 (ko) | 2013-03-26 | 2014-03-17 | 프레스 성형품 및 그 제조 방법 |
CN201480017028.4A CN105050743B (zh) | 2013-03-26 | 2014-03-17 | 冲压成形品及其制造方法 |
US14/780,321 US9744744B2 (en) | 2013-03-26 | 2014-03-17 | Press-formed article and method for manufacturing same |
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JP2013-065233 | 2013-03-26 | ||
JP2013065233A JP6002072B2 (ja) | 2013-03-26 | 2013-03-26 | プレス成形品の製造方法 |
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EP (1) | EP2979771A4 (ja) |
JP (1) | JP6002072B2 (ja) |
KR (1) | KR101719446B1 (ja) |
CN (1) | CN105050743B (ja) |
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Cited By (1)
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EP3228399A4 (en) * | 2014-12-02 | 2017-12-27 | JFE Steel Corporation | Methods for evaluating and manufacturing hot-press formed article |
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AU2016434720A1 (en) * | 2016-12-26 | 2019-07-18 | Nippon Steel Nisshin Co., Ltd. | Surface-treated steel plate component having cut end surface, and cutting method therefor |
CN109323062A (zh) * | 2018-10-31 | 2019-02-12 | 武汉市计量测试检定(研究)所 | 一种变径式流量万用接头及其制备方法 |
KR102405945B1 (ko) | 2020-12-03 | 2022-06-07 | (주)대신에스엔씨 | 프레스 금형 |
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2013
- 2013-03-26 JP JP2013065233A patent/JP6002072B2/ja not_active Expired - Fee Related
-
2014
- 2014-03-17 WO PCT/JP2014/057204 patent/WO2014156790A1/ja active Application Filing
- 2014-03-17 KR KR1020157026230A patent/KR101719446B1/ko active IP Right Grant
- 2014-03-17 EP EP14775588.8A patent/EP2979771A4/en not_active Withdrawn
- 2014-03-17 US US14/780,321 patent/US9744744B2/en not_active Expired - Fee Related
- 2014-03-17 CN CN201480017028.4A patent/CN105050743B/zh not_active Expired - Fee Related
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JP2006104527A (ja) * | 2004-10-06 | 2006-04-20 | Nippon Steel Corp | 高強度部品の製造方法と高強度部品 |
JP2006152361A (ja) * | 2004-11-29 | 2006-06-15 | Jfe Steel Kk | 薄鋼板およびその製造方法、並びに形状凍結性に優れた部品の製造方法 |
JP2008284610A (ja) * | 2007-04-20 | 2008-11-27 | Nippon Steel Corp | 高強度部品の製造方法および高強度部品 |
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EP2979771A1 (en) | 2016-02-03 |
CN105050743B (zh) | 2018-01-30 |
EP2979771A4 (en) | 2016-11-02 |
JP6002072B2 (ja) | 2016-10-05 |
KR101719446B1 (ko) | 2017-03-23 |
US9744744B2 (en) | 2017-08-29 |
US20160039180A1 (en) | 2016-02-11 |
KR20150123860A (ko) | 2015-11-04 |
CN105050743A (zh) | 2015-11-11 |
JP2014188542A (ja) | 2014-10-06 |
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