JP6152836B2 - Manufacturing method of hot press-formed product - Google Patents
Manufacturing method of hot press-formed product Download PDFInfo
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- JP6152836B2 JP6152836B2 JP2014195530A JP2014195530A JP6152836B2 JP 6152836 B2 JP6152836 B2 JP 6152836B2 JP 2014195530 A JP2014195530 A JP 2014195530A JP 2014195530 A JP2014195530 A JP 2014195530A JP 6152836 B2 JP6152836 B2 JP 6152836B2
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- steel sheet
- cooling
- press
- temperature
- plating layer
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- 238000004519 manufacturing process Methods 0.000 title claims description 20
- 229910000831 Steel Inorganic materials 0.000 claims description 169
- 239000010959 steel Substances 0.000 claims description 169
- 238000001816 cooling Methods 0.000 claims description 98
- 238000007747 plating Methods 0.000 claims description 77
- 238000000465 moulding Methods 0.000 claims description 64
- 238000000034 method Methods 0.000 claims description 42
- 229910007567 Zn-Ni Inorganic materials 0.000 claims description 32
- 229910007614 Zn—Ni Inorganic materials 0.000 claims description 32
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 17
- 230000008569 process Effects 0.000 claims description 17
- 238000010791 quenching Methods 0.000 claims description 13
- 230000009466 transformation Effects 0.000 claims description 13
- 230000000171 quenching effect Effects 0.000 claims description 12
- 238000007731 hot pressing Methods 0.000 claims description 4
- 229910052742 iron Inorganic materials 0.000 claims description 3
- 239000010410 layer Substances 0.000 description 59
- 239000011701 zinc Substances 0.000 description 23
- 230000007423 decrease Effects 0.000 description 18
- 238000010438 heat treatment Methods 0.000 description 17
- 238000012545 processing Methods 0.000 description 16
- 230000000694 effects Effects 0.000 description 15
- 230000000052 comparative effect Effects 0.000 description 14
- 238000007710 freezing Methods 0.000 description 14
- 230000008014 freezing Effects 0.000 description 14
- 238000003825 pressing Methods 0.000 description 13
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 11
- 239000010960 cold rolled steel Substances 0.000 description 10
- 239000000463 material Substances 0.000 description 8
- 230000007797 corrosion Effects 0.000 description 7
- 238000005260 corrosion Methods 0.000 description 7
- 229910045601 alloy Inorganic materials 0.000 description 6
- 239000000956 alloy Substances 0.000 description 6
- 229910000734 martensite Inorganic materials 0.000 description 6
- 239000010953 base metal Substances 0.000 description 5
- 238000005452 bending Methods 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- 229910052751 metal Inorganic materials 0.000 description 5
- 229910052759 nickel Inorganic materials 0.000 description 5
- 229910000859 α-Fe Inorganic materials 0.000 description 5
- 229910001566 austenite Inorganic materials 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
- 230000008859 change Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000009713 electroplating Methods 0.000 description 4
- 229910001338 liquidmetal Inorganic materials 0.000 description 4
- 238000002844 melting Methods 0.000 description 4
- 230000008018 melting Effects 0.000 description 4
- 229910052750 molybdenum Inorganic materials 0.000 description 4
- 238000005554 pickling Methods 0.000 description 4
- 229920006395 saturated elastomer Polymers 0.000 description 4
- 238000007493 shaping process Methods 0.000 description 4
- 238000005728 strengthening Methods 0.000 description 4
- 239000002344 surface layer Substances 0.000 description 4
- 229910052720 vanadium Inorganic materials 0.000 description 4
- 229910052725 zinc Inorganic materials 0.000 description 4
- RZLVQBNCHSJZPX-UHFFFAOYSA-L zinc sulfate heptahydrate Chemical compound O.O.O.O.O.O.O.[Zn+2].[O-]S([O-])(=O)=O RZLVQBNCHSJZPX-UHFFFAOYSA-L 0.000 description 4
- 229910052804 chromium Inorganic materials 0.000 description 3
- 238000005336 cracking Methods 0.000 description 3
- 238000005238 degreasing Methods 0.000 description 3
- 238000007598 dipping method Methods 0.000 description 3
- 238000010097 foam moulding Methods 0.000 description 3
- 229910052748 manganese Inorganic materials 0.000 description 3
- 229910052698 phosphorus Inorganic materials 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 238000011282 treatment Methods 0.000 description 3
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 238000005275 alloying Methods 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- 238000000137 annealing Methods 0.000 description 2
- 229910001563 bainite Inorganic materials 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000005097 cold rolling Methods 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 238000005246 galvanizing Methods 0.000 description 2
- 238000005098 hot rolling Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- RRIWRJBSCGCBID-UHFFFAOYSA-L nickel sulfate hexahydrate Chemical compound O.O.O.O.O.O.[Ni+2].[O-]S([O-])(=O)=O RRIWRJBSCGCBID-UHFFFAOYSA-L 0.000 description 2
- 229940116202 nickel sulfate hexahydrate Drugs 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 238000004381 surface treatment Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 230000037303 wrinkles Effects 0.000 description 2
- 241000219307 Atriplex rosea Species 0.000 description 1
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 1
- 229910003962 NiZn Inorganic materials 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000005422 blasting Methods 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 230000003449 preventive effect Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 150000003568 thioethers Chemical class 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
Classifications
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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
-
- 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
- B21D22/201—Work-pieces; preparation of the work-pieces, e.g. lubricating, coating
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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
-
- 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
- B21D37/00—Tools as parts of machines covered by this subclass
- B21D37/16—Heating or cooling
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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
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C18/00—Alloys based on zinc
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
-
- C—CHEMISTRY; METALLURGY
- 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
- C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
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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
- C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
- C23C2/022—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by heating
- C23C2/0224—Two or more thermal pretreatments
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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
- C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
- C23C2/024—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by cleaning or etching
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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
- C23C30/00—Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process
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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
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F17/00—Multi-step processes for surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by subclass C21D or C22F or class C25
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D3/00—Electroplating: Baths therefor
- C25D3/02—Electroplating: Baths therefor from solutions
- C25D3/56—Electroplating: Baths therefor from solutions of alloys
- C25D3/565—Electroplating: Baths therefor from solutions of alloys containing more than 50% by weight of zinc
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
- C25D5/48—After-treatment of electroplated surfaces
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Thermal Sciences (AREA)
- Physics & Mathematics (AREA)
- Crystallography & Structural Chemistry (AREA)
- Electrochemistry (AREA)
- Shaping Metal By Deep-Drawing, Or The Like (AREA)
- Heat Treatment Of Articles (AREA)
- Mounting, Exchange, And Manufacturing Of Dies (AREA)
- Other Surface Treatments For Metallic Materials (AREA)
Description
本発明は、熱間プレス成形品およびその製造方法に関し、特に予め加熱された表面処理鋼板をプレス加工する際に、形状付与と同時に焼入れて所定強度を得る熱間プレス成形品の製造方法および熱間プレス成形品に関するものである。 The present invention relates to a hot press-formed product and a method for manufacturing the same, and in particular, when a surface-treated steel sheet that has been preheated is pressed, a method and a method for manufacturing a hot press-formed product that obtains a predetermined strength by quenching simultaneously with shape formation. It is related to hot press molded products.
近年、自動車部品の高強度化・薄肉化が要求され、使用される鋼板の高強度化に伴ってプレス加工性が低下し、鋼板を所望の部品形状に加工することが難しくなっている。
このような問題を解決するものとして、高温に加熱した素材鋼板を、金型を用いて所望の形状に熱間プレス成形しつつ金型内で抜熱して焼入れし、熱間プレス成形後の部品を高強度化する技術が知られている。
例えば、特許文献１には900℃前後のオーステナイト単相域まで加熱したブランク板（鋼板）に熱間プレスを施して所定形状の部品を製造するに際し、熱間プレス成形と同時に金型内で焼入れを行うことで、部品の高強度化を図る技術が提案されている。
In recent years, high strength and thinning of automobile parts have been demanded, and press workability has deteriorated with the increase in strength of steel sheets used, and it has become difficult to process steel sheets into desired part shapes.
In order to solve such problems, a steel plate heated to a high temperature is subjected to hot press molding into a desired shape using a mold, and the heat is extracted and quenched in the mold, and the parts after hot press molding A technique for increasing the strength of the steel is known.
For example, Patent Document 1 discloses that when a blank plate (steel plate) heated to an austenite single phase region around 900 ° C. is hot pressed to produce a part having a predetermined shape, it is quenched in the mold simultaneously with hot press forming. A technique for increasing the strength of parts by performing the above has been proposed.
しかし、特許文献1で提案された技術では、プレス前に鋼板を900℃前後の高温に加熱する際、鋼板表面に酸化スケール（鉄酸化物）が生成し、その酸化スケールが熱間プレス成形時に剥離して金型を損傷させたり、熱間プレス成形後の部材表面を損傷させるという問題がある。また、部材表面に残った酸化スケールは、外観不良や塗装密着性の低下の原因にもなる。このため、通常は酸洗やショットブラストなどの処理を行って部材表面の酸化スケールを除去するが、これらの処理は生産性の低下を招く。更に、自動車の足回り部材や車体構造部材などには優れた耐食性も必要とされるが、特許文献1で提案された技術では素材鋼板にめっき層などの防錆皮膜が設けられていないため、熱間プレス成形部材の耐食性が不十分となる。 However, in the technique proposed in Patent Document 1, when the steel plate is heated to a high temperature of about 900 ° C. before pressing, oxide scale (iron oxide) is generated on the surface of the steel plate, and the oxide scale is formed during hot press forming. There exists a problem of peeling and damaging a metal mold | die or damaging the member surface after hot press molding. In addition, the oxide scale remaining on the surface of the member also causes poor appearance and poor paint adhesion. For this reason, usually, treatment such as pickling or shot blasting is performed to remove the oxidized scale on the surface of the member, but these treatments cause a decrease in productivity. Furthermore, excellent corrosion resistance is also required for automobile underbody members and vehicle body structural members, etc., but the technology proposed in Patent Document 1 does not have a rust preventive film such as a plating layer on the material steel plate, Corrosion resistance of the hot press-formed member becomes insufficient.
上記の理由により、熱間プレス成形前の加熱時に酸化スケールの生成を抑制するとともに、熱間プレス成形後の部材の耐食性を向上させることが可能な熱間プレス成形技術が要望されている。このような要望に対し、表面にめっき層などの皮膜を設けた表面処理鋼板や、表面処理鋼板を用いた熱間プレス成形方法が提案されている。例えば特許文献２には、ZnまたはZnベース合金で被覆された鋼板を、700〜1200℃に加熱した後、熱間プレス成形することにより、表面にZn-Feベース化合物またはZn-Fe-Alベース化合物を備えた熱間プレス成形部材とする技術が提案されている。また、特許文献２には、ZnまたはZnベース合金で被覆された鋼板を用いることにより、熱間プレス成形前の加熱時に問題となる鋼板表面の酸化を抑制することが可能となり、しかも耐食性に優れた熱間プレス成形部材が得られると記載されている。 For the above reasons, there is a demand for a hot press molding technique that can suppress the formation of oxide scale during heating before hot press molding and can improve the corrosion resistance of members after hot press molding. In response to such a demand, a surface-treated steel sheet provided with a coating such as a plating layer on the surface and a hot press forming method using the surface-treated steel sheet have been proposed. For example, in Patent Document 2, a steel sheet coated with Zn or a Zn base alloy is heated to 700 to 1200 ° C. and then hot pressed to form a Zn—Fe base compound or a Zn—Fe—Al base on the surface. A technique for forming a hot press-formed member provided with a compound has been proposed. Further, in Patent Document 2, by using a steel sheet coated with Zn or a Zn base alloy, it becomes possible to suppress the oxidation of the steel sheet surface, which becomes a problem during heating before hot press forming, and has excellent corrosion resistance. Further, it is described that a hot press-formed member is obtained.
特許文献２で提案された技術によると、熱間プレス成形部材表面の酸化スケール生成はある程度抑制される。しかし、めっき層中のZnに起因する液体金属脆化割れが起こり、熱間プレス成形部材の表層部に深さ100μm程度のクラックが発生する場合がある。このようなクラックが発生すると、熱間プレス成形部材の耐疲労特性が低下するなど、様々な支障をきたす。 According to the technique proposed in Patent Document 2, generation of oxide scale on the surface of a hot press-formed member is suppressed to some extent. However, liquid metal embrittlement cracking due to Zn in the plating layer occurs, and a crack having a depth of about 100 μm may occur in the surface layer portion of the hot press-formed member. When such a crack occurs, various troubles such as deterioration of the fatigue resistance of the hot press-formed member are caused.
このような問題に対し、特許文献３では、Zn-Fe系めっき層が素地鋼板表面に形成された表面処理鋼板を、前記表面処理鋼板を素地鋼板のAc1変態点以上950℃以下の温度に加熱し、めっき層の凝固点以下の温度まで表面処理鋼板を冷却した後、成形を開始する方法が提案されている。そして、特許文献３には、めっき層の凝固点以下の温度まで表面処理鋼板を冷却してから成形を開始することにより、液体金属脆化の抑制が可能であると記載されている。 With respect to such a problem, in Patent Document 3, a surface-treated steel sheet in which a Zn-Fe-based plating layer is formed on the surface of the base steel sheet is heated to a temperature not lower than the Ac1 transformation point of the base steel sheet and not higher than 950 ° C. And the method of starting shaping | molding after cooling a surface-treated steel plate to the temperature below the freezing point of a plating layer is proposed. Patent Document 3 describes that liquid metal embrittlement can be suppressed by cooling the surface-treated steel sheet to a temperature not higher than the freezing point of the plating layer and then starting forming.
特許文献３で提案された技術によると、液体金属脆化割れ、すなわち熱間プレス成形部材の表面に発生し、めっき層-地鉄界面から地鉄内部方向への深さが100μm程度であって、割れ部の界面にZnが検出されるクラック（以下、「マクロクラック」という）を抑制し得ると考えられる。このようなマクロクラックの抑制に対して、本発明者らは高融点のめっき層としてZnに9〜25％程度のNiを含有したZn-Ni合金めっきを用いることを検討した。Zn-Ni合金めっきの耐食性確保にはZn-Ni合金をγ相とする必要があり、Zn-Ni合金の平衡状態図に存在するγ相は融点が860℃以上と通常のZn系めっき層に比べて非常に高く、通常のプレス条件でもマクロクラックの発生が抑制可能となる。
しかしながら、熱間プレス成形部材の表面には、上記のマクロクラックではなく、めっき層-地鉄界面から地鉄内部方向への深さが約30μm以下であって、割れ部の界面にはZnが検出されない微小割れが発生することが知られている。この微小割れはミクロクラックと称され、めっき層-地鉄界面を貫通して地鉄（素地鋼板）の内部にまで至り、熱間プレス成形部材の諸特性（耐疲労特性等）に悪影響を及ぼす。
マクロクラックは、例えば、ハット断面部材をプレス成形する際に、ダイ肩Ｒ部のパンチ接触側のような引張り歪のみが生ずる部分でも発生するが、一方、ミクロクラックはそのような部分では発生せず、縦壁部のダイ接触側のような（曲げ）圧縮の後（曲げ戻し）引張り歪を受けるところで発生するものであり、両者ではその発生のメカニズムが異なると推察される。
According to the technique proposed in Patent Document 3, liquid metal embrittlement cracks occur, that is, occur on the surface of a hot press-formed member, and the depth from the plating layer-base metal interface to the inside of the base metal is about 100 μm. It is considered that cracks in which Zn is detected at the interface of the cracked portion (hereinafter referred to as “macro crack”) can be suppressed. In order to suppress such macro cracks, the present inventors examined the use of Zn—Ni alloy plating containing about 9 to 25% Ni in Zn as a high melting point plating layer. In order to ensure the corrosion resistance of Zn-Ni alloy plating, it is necessary to use Zn-Ni alloy as the γ phase. The γ phase present in the equilibrium diagram of the Zn-Ni alloy has a melting point of 860 ° C or higher and becomes a normal Zn-based plating layer. It is very high compared to the above, and the occurrence of macro cracks can be suppressed even under normal pressing conditions.
However, on the surface of the hot press-formed member, the depth from the plating layer-base metal interface to the inside of the iron core is not more than about 30 μm, not Zn, and Zn is not present at the interface of the cracked part. It is known that microcracks that are not detected occur. This microcrack is called a microcrack and penetrates through the plating layer-base metal interface to the inside of the base metal (base steel plate), which adversely affects various properties (such as fatigue resistance) of hot press-formed members. .
For example, when a hat cross-section member is press-molded, macro cracks occur even in portions where only tensile strain occurs, such as the punch contact side of the die shoulder R, whereas micro cracks do not occur in such portions. However, it occurs when subjected to a tensile strain after (bending) compression (bending back) as on the die contact side of the vertical wall, and it is assumed that the generation mechanism is different between the two.
特許文献３では、Zn-Fe系めっき層が形成された表面処理鋼板についてマクロクラックの発生抑制は可能であるが、Zn-Niめっき層が形成された表面処理鋼板におけるミクロクラックのことは何らの考慮もされておらず、ミクロクラック発生抑制には必ずしも有効とは言えない。
また、特許文献３で提案された技術では、表面処理鋼板全体をめっき層の凝固点以下の温度まで冷却した状態でプレス成形するとしており、プレス成形を開始する温度の下限値が示されておらず、成形温度の低下によりプレス成形時の鋼板の強度上昇が起こり、形状凍結性（スプリングバック等がわずかでプレス下死点での形状が維持される性質）が低下してスプリングバックが起きやすいという問題もある。
In Patent Document 3, it is possible to suppress the occurrence of macro cracks in a surface-treated steel sheet on which a Zn-Fe-based plating layer is formed, but what are the microcracks in a surface-treated steel sheet in which a Zn-Ni plating layer is formed? It has not been taken into consideration, and is not necessarily effective in suppressing the occurrence of microcracks.
In the technique proposed in Patent Document 3, the entire surface-treated steel sheet is press-formed while being cooled to a temperature below the freezing point of the plating layer, and the lower limit value of the temperature at which press forming is started is not shown. The strength of the steel sheet during press forming increases due to the decrease in the forming temperature, and the shape freezing property (the property of maintaining the shape at the bottom dead center of the press with a slight spring back etc.) decreases and the spring back is likely to occur. There is also a problem.
本発明はかかる問題を解決するためになされたものであり、Zn-Ni系めっき層を形成した表面処理鋼板に熱間プレスを施して熱間プレス成形部材を製造するに際し、熱間プレス成形時の形状凍結性の低下を抑制しつつ、ミクロクラックの発生を抑制する熱間プレス成形品の製造方法および熱間プレス成形品を提供することを目的としている。 The present invention has been made in order to solve such a problem. When a hot-pressed member is manufactured by hot-pressing a surface-treated steel sheet on which a Zn-Ni-based plating layer is formed, An object of the present invention is to provide a method for producing a hot press-molded product and a hot press-molded product that suppress the occurrence of microcracks while suppressing a decrease in shape freezing property.
本発明者らは、Zn系めっき鋼板を熱間プレス成形する際に問題となるミクロクラック（微小割れ）を抑制する手段について検討した。
ミクロクラックの生成メカニズムについては明確になっていないが、Zn系のめっき鋼板をめっき凝固点以下の高温でプレス成形することによりめっき鋼板の表面に微小割れが発生し、Zn-Niめっきにおいても同様に起こる。この微小割れは、めっき層-素地鋼板界面からの深さが30μm程度の微小な割れであり、めっき層-素地鋼板界面を貫通して素地鋼板内部に至る。このような問題に対し、本発明者らが種々の検討を行った結果、熱間プレス成形時の温度を低くすることによりミクロクラックが抑制されることを明らかにした。更に、上記のようなプレス成形時の温度低下により、従来の熱間プレス用めっき鋼板で問題となっている金型へのめっき付着量も大幅に低減する効果が得られた。
The present inventors have studied a means for suppressing microcracks (microcracks) that are problematic when hot-pressing a Zn-based plated steel sheet.
Although the microcrack formation mechanism is not clear, micro-cracking occurs on the surface of the plated steel sheet by press-forming a Zn-based plated steel sheet at a high temperature below the freezing point of plating, and the same applies to Zn-Ni plating. Occur. This microcrack is a microcrack having a depth of about 30 μm from the plating layer-base steel plate interface and penetrates the plating layer-base steel plate interface to the inside of the base steel plate. As a result of various studies conducted by the present inventors for such problems, it has been clarified that microcracks are suppressed by lowering the temperature during hot press molding. Furthermore, due to the temperature drop during press forming as described above, the effect of greatly reducing the amount of plating adhered to the mold, which is a problem with conventional hot-pressed plated steel sheets, was obtained.
しかし、プレス成形時の鋼板温度が低くなると、鋼板の強度が上昇するため形状凍結性の低下が起こり、熱間プレス成形時の利点を生かすことができなくなる。
そこで、本発明者らは、プレス成形時にミクロクラックが発生するような加工を受ける部分のみを冷却した後、熱間プレス成形すればよいと考え、前記ミクロクラックが発生する加工とはいかなる加工であり、当該加工を受ける部分とはいかなる部分かについて検討した。
まず、ミクロクラックが発生する加工について検討するに際し、加工歪みがミクロクラックの発生に及ぼす影響を種々検討した。その結果、単なる引張り、圧縮変形や曲げ変形のみではミクロクラックは発生せず、一旦曲げられた部分が再度伸ばされる、曲げ-曲げ戻し変形を受ける部分でミクロクラックが発生することを明らかにした。
上記のような加工は、成形品の形状によっては特定の箇所に限定されるが、成形品の形状が種々のものになれば、ミクロクラックが発生する加工を受ける部位が鋼板の全面に及ぶ場合もある。
However, when the steel plate temperature during press forming decreases, the strength of the steel plate increases and the shape freezing property decreases, making it impossible to take advantage of the advantages during hot press forming.
Therefore, the present inventors consider that it is sufficient to perform hot press molding after cooling only a portion subjected to processing that generates micro cracks during press molding, and what is the processing in which the micro cracks are generated? Yes, we examined what part is subject to the processing.
First, when examining the processing in which microcracks occur, various effects of processing strain on the occurrence of microcracks were examined. As a result, it was clarified that micro-cracks do not occur only by simple tension, compression deformation and bending deformation, but micro-cracks occur in the portion subjected to bending-bending unbending deformation, where the once bent portion is stretched again.
The processing as described above is limited to a specific part depending on the shape of the molded product, but if the shape of the molded product becomes various, the part subjected to processing that generates micro cracks covers the entire surface of the steel plate. There is also.
そこで、被加工部材である鋼板の特定部位に限定されることなくミクロクラックの発生を抑制できる方法について検討し、その結果、プレス成形前に鋼板のほぼ全面に接触することができる冷却用金型で鋼板を挟んで鋼板温度が550℃以下410℃以上になる時間を保持して冷却を行い、その後に鋼板温度が550℃以下400℃以上でプレス成形を開始することで鋼板の全面に亘ってミクロクラックの発生を抑制しつつ、形状精度不良も抑制可能となることが明らかとなった。 Therefore, we examined a method that can suppress the occurrence of microcracks without being limited to a specific part of the steel plate that is the workpiece, and as a result, a cooling mold that can contact almost the entire surface of the steel plate before press forming. The steel sheet is held at a temperature of 550 ° C or lower and 410 ° C or higher for cooling, and then press forming is started when the steel plate temperature is 550 ° C or lower and 400 ° C or higher. It has been clarified that it is possible to suppress poor shape accuracy while suppressing the occurrence of microcracks.
冷却用金型での冷却により形状精度不良が抑制された理由については以下のように考えられる。ハット型部材の代表的な形状精度不良としては、曲げの稜線を挟む２つの面のなす角度が金型角度に対して大きくなる角度変化と、縦壁部の平面が曲率を持った面になる壁反りが挙げられる。これらはいずれも板厚方向の応力分布の差により生じ、加工時の鋼板の流動応力が高いほど、応力分布の差が拡大して形状精度が低下する。すなわち、熱間プレスにおいては、加工温度が低いほど鋼板の加工時の流動応力が高くなり形状精度が低下する。冷却により加工時の鋼板の温度が低くなり形状精度が低下すると考えられるが、鋼板温度が410℃以上となる保持時間まで冷却し、その後に400℃以上でプレス成形を開始することにより、ほとんど形状精度の低下は認められなかった。これは、鋼板温度が400℃以上ではプレス加工時の組織がオーステナイトであり、加工後にマルテンサイト変態して加工時に入った応力が緩和され形状精度の低下が起こらなかったと考えられる。
逆に保持時間が長くなり鋼板温度が400℃未満となると、プレス加工時に既にマルテンサイトに変態しているため、鋼板強度の増加も加わって、加工時に入った応力により壁反りが発生すると考えられる。
本発明は、上記のような知見に基づいてなされたものであり、具体的には以下の構成を備えてなるものである。
The reason why the shape accuracy defect is suppressed by cooling with the cooling mold is considered as follows. A typical shape accuracy failure of the hat-shaped member is that the angle formed by the two surfaces sandwiching the bending ridge line becomes larger with respect to the mold angle, and the plane of the vertical wall portion has a curved surface. Wall warping can be mentioned. These are all caused by the difference in stress distribution in the thickness direction, and the higher the flow stress of the steel sheet during processing, the greater the difference in stress distribution and the lower the shape accuracy. That is, in the hot press, the lower the processing temperature, the higher the flow stress during processing of the steel sheet and the lower the shape accuracy. Although it is considered that the steel sheet temperature during processing decreases due to cooling, the shape accuracy is lowered, but the shape is almost reduced by cooling to a holding time where the steel sheet temperature is 410 ° C or higher and then starting press forming at 400 ° C or higher. No decrease in accuracy was observed. This is probably because when the steel plate temperature is 400 ° C. or higher, the structure at the time of pressing is austenite, the martensite transformation after the processing is relaxed, and the stress entered at the time of processing is relieved and the shape accuracy does not decrease.
Conversely, if the holding time is long and the steel sheet temperature is less than 400 ° C, it has already transformed into martensite at the time of press processing, so the increase in steel sheet strength is also added, and it is thought that wall warpage occurs due to the stress entered during processing .
The present invention has been made on the basis of the above-described knowledge, and specifically comprises the following configuration.
（１）本発明に係る熱間プレス成形品の製造方法は、Zn-Niめっき層が素地鋼板の表面に形成された表面処理鋼板に熱間プレスを施して熱間プレス成形品を製造する熱間プレス成形品の製造方法であって、Ac3変態点以上で1000℃以下の温度域に加熱した前記表面処理鋼板の全面を、前記表面処理鋼板との接触面が平面である冷却用金型を用いて、前記表面処理鋼板が800℃以下670℃以上になっているタイミングで、100℃/s以上の冷却速度で550℃以下410℃以上の温度まで冷却する冷却工程と、冷却後5秒以内にプレス成形金型を用いて鋼板温度が550℃以下400℃以上の範囲内でプレス成形を開始するプレス成形工程と、前記表面処理鋼板を前記プレス成形金型で挟んだまま保持して前記表面処理鋼板を焼入れる焼入れ工程とを備え、Zn-Niめっき層−地鉄界面から地鉄内部方向への深さが約30μm以下であってミクロクラックと称する微小割れの発生を防止することを特徴とするものである。 (1) The method for producing a hot press-formed product according to the present invention is a method for producing a hot press-formed product by subjecting a surface-treated steel plate having a Zn-Ni plating layer formed on the surface of a base steel plate to a hot press. A method for producing an intermediate press-formed product, comprising: a cooling die having a flat contact surface with the surface-treated steel sheet over the entire surface of the surface-treated steel sheet heated to a temperature range of 1000 ° C. or higher but not lower than the Ac3 transformation point. Using the cooling process to cool the surface-treated steel sheet to a temperature of 800 ° C or lower and 670 ° C or higher at a cooling rate of 100 ° C / s or higher to a temperature of 550 ° C or lower and 410 ° C or higher, and within 5 seconds after cooling A press forming step in which press forming is started within a range where the steel plate temperature is 550 ° C. or lower and 400 ° C. or higher using a press forming die, and the surface treated steel plate is held while being sandwiched between the press forming dies and the surface With a quenching process for quenching the treated steel sheet, Zn-Ni plating layer- The depth from the surface to the inside of the ground iron is about 30 μm or less, and the occurrence of microcracks called microcracks is prevented .
本発明においては、Zn-Niめっき層が素地鋼板の表面に形成された表面処理鋼板に熱間プレスを施して熱間プレス成形品を製造する熱間プレス成形品の製造方法であって、Ac3変態点以上で1000℃以下の温度域に加熱した前記表面処理鋼板全面を、前記表面処理鋼板との接触面が平面である冷却用金型を用いて、100℃/s以上の冷却速度で550℃以下410℃以上の温度まで冷却する冷却工程と、冷却後5秒後以内に前記表面処理鋼板の温度が550℃以下400℃以上の範囲でプレス成形を開始するプレス成形工程と、前記表面処理鋼板を金型で挟んだまま保持して前記表面処理鋼板を焼入れる焼入れ工程とを備えたことにより、どのような製品形状をプレス成形加工する場合でも、ミクロクラックが発生することなく、成形品の硬度も十分であり、大幅な成形荷重の増加もなく、形状凍結性としても問題ないという効果が得られる。 In the present invention, a hot press-formed product manufacturing method for manufacturing a hot press-formed product by subjecting a surface-treated steel plate having a Zn-Ni plated layer formed on the surface of a base steel plate to hot press, is provided. The entire surface-treated steel sheet heated to a temperature range of not less than the transformation point and not more than 1000 ° C. is 550 at a cooling rate of 100 ° C./s or more using a cooling mold having a flat contact surface with the surface-treated steel sheet. A cooling step of cooling to a temperature of not higher than 410 ° C and a temperature of not lower than 410 ° C, a press forming step of starting press forming in a range where the temperature of the surface-treated steel sheet is not higher than 550 ° C and not lower than 400 ° C within 5 seconds after cooling, and the surface treatment By holding the steel sheet sandwiched between molds and quenching the surface-treated steel sheet, the molded product can be produced without any micro-cracking in any product shape. Has sufficient hardness and a large molding load Increases without, effect that even no problem as shape fixability.
本発明の一実施の形態に係る熱間プレス成形品の製造方法は、Zn-Niめっき層が素地鋼板の表面に形成された表面処理鋼板１に熱間プレスを施して熱間プレス成形品を製造する熱間プレス成形品の製造方法であって、図１に示すように、Ac3変態点以上で1000℃以下の温度域に加熱した表面処理鋼板１を、表面処理鋼板１との接触面が平面である冷却用金型３を用いて挟んで100℃/s以上の冷却速度で550℃以下410℃以上の温度まで冷却する冷却工程（Ｓ１）と、冷却後5秒以内にプレス成形金型１１を用いて鋼板温度が500℃以下400℃以上の範囲内でプレス成形を開始するプレス成形工程（Ｓ２）と、表面処理鋼板１をプレス成形金型１１で挟んだまま保持して表面処理鋼板１を焼入れる焼入れ工程（Ｓ３）とを備えたものである。
以下、熱間プレス成形部材の素材、冷却工程（Ｓ１）、プレス成形工程（Ｓ２）、焼入れ工程（Ｓ３）について詳細に説明する。
The method for manufacturing a hot press-formed product according to an embodiment of the present invention includes a hot press-formed product obtained by hot-pressing a surface-treated steel plate 1 having a Zn-Ni plating layer formed on the surface of a base steel plate. A method of manufacturing a hot press-formed product to be manufactured, as shown in FIG. 1, a surface-treated steel sheet 1 heated to a temperature range of not less than Ac3 transformation point and not more than 1000 ° C. has a contact surface with the surface-treated steel sheet 1. A cooling step (S1) in which a flat cooling die 3 is sandwiched and cooled to a temperature of 550 ° C. or lower and 410 ° C. or higher at a cooling rate of 100 ° C./s or higher, and a press mold within 5 seconds after cooling. 11 and press forming step (S2) in which press forming is started within a range where the steel plate temperature is 500 ° C. or lower and 400 ° C. or higher, and the surface-treated steel plate 1 is held while being sandwiched between the press-molding dies 11. And a quenching step (S3) for quenching 1.
Hereinafter, the raw material of the hot press-formed member, the cooling step (S1), the press-forming step (S2), and the quenching step (S3) will be described in detail.
＜熱間プレス成形部材の素材＞
熱間プレス成形部材の素材としては、素地鋼板の表面にZn-Niめっき層が設けられたものを用いる。鋼板表面にZn-Niめっき層を設けることにより、熱間プレス成形後の部材の耐食性を確保することができる。
素地鋼板表面にZn-Niめっき層を形成する方法は特に限定されず、溶融めっき、電気めっきなどいずれの方法でもよい。めっきの付着量は、片面あたり10g/m2以上90g/m2以下とすることが好ましい。
<Hot press-molded material>
As a raw material for the hot press-formed member, a material in which a Zn—Ni plating layer is provided on the surface of a base steel plate is used. By providing the Zn—Ni plating layer on the surface of the steel sheet, the corrosion resistance of the member after hot press forming can be ensured.
The method for forming the Zn—Ni plating layer on the surface of the base steel plate is not particularly limited, and any method such as hot dipping or electroplating may be used. The amount of plating is preferably 10 g / m 2 or more and 90 g / m 2 or less per side.
めっき層中のNi含有量を9質量%以上25質量%以下とすることが好ましい。電気めっき法によりZn-Niめっき層を素地鋼板表面に形成する際、めっき層中のNi含有量を9質量%以上25質量%以下とすることで、Ni2Zn11，NiZn3、Nｉ5Zn21のいずれかの結晶構造を有するγ相が形成される。このγ相は融点が高いことから、熱間プレス成形前の表面処理鋼板加熱時に懸念されるめっき層の蒸発を抑制する上で有利となる。また、高温の熱間プレス成形時に問題となる液体金属脆化の抑制にも有利となる。 The Ni content in the plating layer is preferably 9% by mass or more and 25% by mass or less. When the Zn-Ni plating layer is formed on the surface of the base steel sheet by electroplating, Ni 2 Zn 11 , NiZn 3 , Ni 5 Zn A γ phase having any one of the 21 crystal structures is formed. Since this γ phase has a high melting point, it is advantageous for suppressing evaporation of the plating layer, which is a concern during heating of the surface-treated steel sheet before hot press forming. It is also advantageous for suppressing liquid metal embrittlement, which is a problem during hot press forming at high temperatures.
表面処理鋼板１は、Ac3変態点以上で1000℃以下の温度域に加熱する。表面処理鋼板１の加熱温度がAc3変態点未満であると、加熱時に適切な量のオーステナイトが得られず、プレス成形時にフェライトが存在することで、熱間プレス成形後に十分な強度を得ることや良好な形状凍結性を確保することが困難となる。一方、表面処理鋼板１の加熱温度が1000℃を越えると、めっき層の蒸発や表層部での酸化物の過度な生成により、耐酸化性や熱間プレス成形部材の耐食性が低下する。したがって、加熱温度はAc3変態点以上1000℃以下とする。より好ましくはAc3変態点+30℃以上950℃以下である。表面処理鋼板１の加熱方法は特に限定されず、電気炉や誘導加熱炉、直接通電加熱炉による加熱等、いずれの方法であってもよい。 The surface-treated steel sheet 1 is heated to a temperature range from the Ac3 transformation point to 1000 ° C. When the heating temperature of the surface-treated steel sheet 1 is lower than the Ac3 transformation point, an appropriate amount of austenite cannot be obtained during heating, and ferrite exists during press forming, so that sufficient strength can be obtained after hot press forming. It becomes difficult to ensure a good shape freezing property. On the other hand, when the heating temperature of the surface-treated steel sheet 1 exceeds 1000 ° C., the oxidation resistance and the corrosion resistance of the hot press-formed member are deteriorated due to evaporation of the plating layer and excessive generation of oxide at the surface layer portion. Accordingly, the heating temperature is set to the Ac3 transformation point or higher and 1000 ° C or lower. More preferably, it is Ac3 transformation point + 30 ° C. or higher and 950 ° C. or lower. The heating method of the surface-treated steel sheet 1 is not particularly limited, and any method such as heating with an electric furnace, an induction heating furnace, or a direct current heating furnace may be used.
＜冷却工程＞
冷却工程（Ｓ１）は、加熱した表面処理鋼板１を冷却用金型３で挟んで100℃/s以上の冷却速度で550℃以下400℃以上の温度まで冷却する工程である。
冷却用金型３は、図１に示すように、表面処理鋼板１との接触面が平面状になっている上金型５と下金型７とを有し、下金型７には伸縮式のリフターピン９が設置されている。加熱した表面処理鋼板１は、リフターピン９上に載置され、その後、上金型５と下金型７とで挟むことで冷却される。
加熱した表面処理鋼板１を冷却用金型３で挟むタイミングとしては、Zn-Niめっき層が金型に付着する危険性のない800℃以下とすることが好ましく、熱間プレス成形後の強度確保の点から670℃以上とすることが好ましい。なお、冷却用金型３は表面処理鋼板１の片側面に押し当てて冷却してもよい。
<Cooling process>
The cooling step (S1) is a step in which the heated surface-treated steel sheet 1 is sandwiched between cooling dies 3 and cooled to a temperature of 550 ° C. or lower and 400 ° C. or higher at a cooling rate of 100 ° C./s or higher.
As shown in FIG. 1, the cooling mold 3 includes an upper mold 5 and a lower mold 7 whose contact surfaces with the surface-treated steel sheet 1 are flat, and the lower mold 7 is extended and contracted. A lifter pin 9 of the type is installed. The heated surface-treated steel sheet 1 is placed on the lifter pin 9 and then cooled by being sandwiched between the upper mold 5 and the lower mold 7.
The timing for sandwiching the heated surface-treated steel sheet 1 with the cooling mold 3 is preferably set to 800 ° C. or less without risk of the Zn—Ni plating layer adhering to the mold, and ensuring the strength after hot press forming. From this point, the temperature is preferably 670 ° C. or higher. The cooling mold 3 may be cooled by pressing against one side surface of the surface-treated steel sheet 1.
冷却速度を100℃/s以上としたのは、コストアップすることなく、マルテンサイト単相組織となり高強度化を可能とするためである。
この点をさらに詳細に説明する。
図２は金属組織と温度、冷却時間との関係を示す模式図である。図２（ａ）は成形開始温度が高い場合を示しており、成形開始後、金型への抜熱によって急冷され、マルテンサイト単相組織となる。
他方、図２（ｂ）に示すように、成形開始温度が低い場合には、成形開始前にフェライトやベイナイトが生成し、プレス成形後の部材強度が低下する。
本発明では、プレス成形開始温度を下げているため、図２（ｂ）の形態となるが、それをプレス開始前に急冷が可能な冷却工程を採用することで、図３の破線の曲線で示すように、成形開始温度を低くしながらも、マルテンサイト単相組織とすることができる。
The reason why the cooling rate is set to 100 ° C./s or more is that a martensite single-phase structure can be obtained without increasing the cost, and high strength can be achieved.
This point will be described in more detail.
FIG. 2 is a schematic diagram showing the relationship between the metal structure, temperature, and cooling time. FIG. 2A shows a case where the molding start temperature is high, and after the molding starts, the mold is rapidly cooled by removing heat into the mold to become a martensite single phase structure.
On the other hand, as shown in FIG. 2B, when the molding start temperature is low, ferrite and bainite are generated before the molding starts, and the strength of the member after press molding is lowered.
In the present invention, since the press molding start temperature is lowered, the configuration shown in FIG. 2 (b) is obtained. By adopting a cooling process that can be rapidly cooled before the press starts, the curve shown by the broken line in FIG. As shown, a martensitic single phase structure can be obtained while lowering the molding start temperature.
冷却工程で550℃以下まで冷却するとしているのは、550℃超では冷却が不十分となり、熱間プレス成形後にミクロクラックが生成するからである。また、冷却温度の下限値を410℃としたのは、この温度を超えて冷却した場合にはプレス成形前に表面処理鋼板１が過度に冷却されてプレス成形後の形状凍結性が低下するからである。 The reason for cooling to 550 ° C. or lower in the cooling step is that if it exceeds 550 ° C., cooling becomes insufficient and microcracks are generated after hot press forming. Further, the lower limit of the cooling temperature is set to 410 ° C., because when the temperature is exceeded and the surface-treated steel sheet 1 is excessively cooled before press forming, the shape freezing property after press forming is lowered. It is.
プレス前の冷却工程における金型での冷却は、冷却用金型３で素材を保持している時間によって制御した（図１参照）。冷却用金型３で表面処理鋼板１を挟むことによる表面処理鋼板１の温度変化については、図４に示す鋼板に0.5mmφのシース熱電対１９を挿入して表面処理鋼板１の温度を測定した。図５はその結果を示すグラフであり、縦軸が温度（℃）、横軸が時間（ｓ）を示している。また、図６は図５における破線で囲んだ部分の横軸を拡大して示すグラフである。金型冷却による温度変化は、図６に示すように、約160℃/sであり急冷が可能であることが分かる。 Cooling in the mold in the cooling step before pressing was controlled by the time during which the material was held in the cooling mold 3 (see FIG. 1). Regarding the temperature change of the surface-treated steel sheet 1 by sandwiching the surface-treated steel sheet 1 with the cooling mold 3, the temperature of the surface-treated steel sheet 1 was measured by inserting a 0.5mmφ sheath thermocouple 19 into the steel sheet shown in FIG. . FIG. 5 is a graph showing the results, where the vertical axis represents temperature (° C.) and the horizontal axis represents time (s). FIG. 6 is a graph showing an enlarged horizontal axis of a portion surrounded by a broken line in FIG. As shown in FIG. 6, the temperature change due to mold cooling is about 160 ° C./s, and it can be seen that rapid cooling is possible.
評価項目としては、プレス成形品の縦壁部の断面を観察して、ミクロクラックの有無を確認すること、成形品の硬度を確認すること、成形荷重を確認すること、成形品のハット開口部の口開き量（成形後に離型した開口部の幅寸法と金型形状での成形品幅との差）を確認することで形状凍結性を確認することである。 As evaluation items, observe the cross section of the vertical wall of the press-molded product to confirm the presence or absence of microcracks, confirm the hardness of the molded product, confirm the molding load, and the hat opening of the molded product. It is to confirm the shape freezing property by confirming the amount of opening (the difference between the width dimension of the opening part released after molding and the width of the molded product in the mold shape).
図７は縦壁部のプレス成形金型１１側の鋼板表層の断面のSEM像であり、金型での冷却時間が0.9s以上（プレス成形開始温度550℃以下）でミクロクラックが認められなくなることが分かる。また、全ての条件でHv＞450であり焼入れ性の低下がないことが確認された。 FIG. 7 is an SEM image of the cross section of the steel sheet surface layer on the press molding die 11 side of the vertical wall, and microcracks are not observed when the cooling time in the die is 0.9 s or more (press molding start temperature 550 ° C. or less). I understand that. Moreover, it was confirmed that Hv> 450 under all conditions and there was no deterioration in hardenability.
図８は成形荷重についての結果を示すグラフであり、縦軸がプレス荷重（kN）を示し、横軸がプレス成形開始温度（℃）を示している。図８のグラフに示されるように、プレス前の金型冷却によるプレス成形開始温度の低下に伴いプレス荷重が増加するが、ミクロクラックの発生が無くなる550℃程度の温度では軟鋼（270D、冷間ドロー成形）と同等レベルの成形荷重であり、問題ないことが確認された。 FIG. 8 is a graph showing the results of the molding load, in which the vertical axis represents the press load (kN) and the horizontal axis represents the press molding start temperature (° C.). As shown in the graph of FIG. 8, the press load increases with a decrease in the press forming start temperature due to die cooling before pressing, but mild steel (270D, cold It was confirmed that there was no problem with the molding load at the same level as that of (draw molding).
図９は形状凍結性についての結果を示すグラフであり、縦軸が成形品の口開き量（mm）を示し、横軸がプレス成形開始温度（℃）を示している。図９のグラフに示すように、プレス成形前の金型冷却による成形開始温度の低下に伴い口開き量が増しており、形状凍結性が低下する傾向を示しているが、プレス成形開始温度が400℃まではほとんど形状凍結性の低下は認められない。 FIG. 9 is a graph showing the results of the shape freezing property, in which the vertical axis represents the opening amount (mm) of the molded product, and the horizontal axis represents the press molding start temperature (° C.). As shown in the graph of FIG. 9, the amount of opening increases as the molding start temperature decreases due to cooling of the mold before press molding, and the shape freezeability tends to decrease. Until 400 ° C, almost no decrease in shape freezing property is observed.
以上のように、550℃以下400℃以上の温度でプレス成形を開始することで、ミクロクラックが発生することなく、成形品の硬度が十分であり、成形荷重が増すこともなく、形状凍結性としても問題ないことが確認された。 As described above, by starting press molding at a temperature of 550 ° C or lower and 400 ° C or higher, microcracks are not generated, the hardness of the molded product is sufficient, the molding load does not increase, and the shape freezing property It was confirmed that there was no problem.
＜プレス成形工程＞
プレス成形工程（Ｓ２）は、表面処理鋼板１を製品形状にプレス成形する工程である。プレス成形工程は、冷却工程の後、５秒以内に開始し、プレス成形金型１１を用いて行う。プレス成形金型１１は、図１に示すように、ダイ１３とパンチ１７を備え、ダイ１３とパンチ１７で表面処理鋼板１を挟むことで成形を行う。
<Press molding process>
The press forming step (S2) is a step of press forming the surface-treated steel sheet 1 into a product shape. The press molding process starts within 5 seconds after the cooling process and is performed using the press molding die 11. As shown in FIG. 1, the press molding die 11 includes a die 13 and a punch 17, and performs molding by sandwiching the surface-treated steel sheet 1 between the die 13 and the punch 17.
冷却工程における表面処理鋼板１の温度が550℃から410℃の間に、冷却用金型３から表面処理鋼板１を抜き出して加工する。
冷却工程の後、5秒以内にプレス成形工程を開始するのは、冷却後、成形を開始するまでの時間が5秒を超えると、プレス成形開始前にフェライトやベイナイトなどの生成が起こり、マルテンサイト単相組織が得られず、プレス成形品の硬度が不十分となるためである。冷却工程後、プレス成形工程開始までの時間は、好ましくは3秒以内である。
While the temperature of the surface-treated steel sheet 1 in the cooling process is between 550 ° C. and 410 ° C., the surface-treated steel sheet 1 is extracted from the cooling mold 3 and processed.
The press molding process is started within 5 seconds after the cooling process. If the time until the molding starts after cooling exceeds 5 seconds, ferrite, bainite, etc. are generated before the start of press molding, and martensite This is because a site single-phase structure cannot be obtained and the hardness of the press-formed product becomes insufficient. The time from the cooling step to the start of the press molding step is preferably within 3 seconds.
プレス成形方法については特に限定されない。図１０(a)に示したように、ダイ１３とブランクホルダ１５で表面処理鋼板１を挟んだまま成形を行うドロー成形、あるいは図１０(b)に示したように、ブランクホルダ１５を下げるか、または、ブランクホルダ１５を使用せずに成形を行うフォーム成形などが可能である。ミクロクラック抑制の観点からは縦壁の加工度合いが小さくなるフォーム成形の方が好ましい。 The press molding method is not particularly limited. As shown in FIG. 10 (a), draw forming is performed with the die 13 and the blank holder 15 sandwiching the surface-treated steel sheet 1, or is the blank holder 15 lowered as shown in FIG. 10 (b)? Alternatively, it is possible to perform foam molding that performs molding without using the blank holder 15. From the viewpoint of suppressing microcracks, foam molding is preferable because the degree of processing of the vertical wall is small.
＜焼入れ工程＞
焼入れ工程は、表面処理鋼板１をプレス成形金型１１で挟んだまま保持して表面処理鋼板１を焼入れる工程である。プレス成形後に金型により表面処理鋼板１を焼入れるためには、プレス成形後に下死点においてスライドを停止することが好ましい。停止時間は金型による抜熱量により異なるが3秒以上とすることが好ましい。
<Hardening process>
The quenching step is a step of quenching the surface-treated steel sheet 1 while holding the surface-treated steel sheet 1 while being sandwiched between the press molds 11. In order to quench the surface-treated steel sheet 1 with a die after press molding, it is preferable to stop the slide at the bottom dead center after press molding. The stop time varies depending on the amount of heat removed by the mold, but is preferably 3 seconds or more.
なお、金型内に所定時間保持して素地鋼板を焼入れ組織とするには、例えば、質量%で、C：0.15%以上0.50%以下、Si：0.05%以上2.00%以下、Mn：0.50%以上3.00%以下、P：0.10%以下、S：0.050%以下、Al：0.10%以下、N：0.010%以下を含有し、残部がFeおよび不可避的不純物からなる成分組成を有する熱延鋼板や冷延鋼板を用いることができる。各成分の限定理由を以下に説明する。ここで、成分の含有量を示す「%」は特に断らない限り「質量%」を意味する。 In order to make the base steel sheet into a quenched structure by holding it in the mold for a predetermined time, for example, in mass%, C: 0.15% to 0.50%, Si: 0.05% to 2.00%, Mn: 0.50% or more 3.00% or less, P: 0.10% or less, S: 0.050% or less, Al: 0.10% or less, N: 0.010% or less, the hot-rolled steel sheet or the cold-rolled steel having a composition composed of Fe and inevitable impurities as the balance A steel plate can be used. The reason for limitation of each component is demonstrated below. Here, “%” indicating the content of a component means “% by mass” unless otherwise specified.
《C：0.15%以上0.50%以下》
Cは鋼の強度を向上させる元素であり、熱間プレス成形部材の高強度化のためにはその量を0.15%以上とすることが好ましい。一方、C量が0.50%を超えると、熱間プレス成形部材の溶接性や素材（素地鋼板）のブランキング性が著しく低下する。したがって、C含有量は0.15%以上0.50%以下とすることが好ましく、0.20%以上0.40%以下とすることがより好ましい。
《C: 0.15% to 0.50%》
C is an element that improves the strength of the steel, and the amount is preferably 0.15% or more in order to increase the strength of the hot press-formed member. On the other hand, when the amount of C exceeds 0.50%, the weldability of the hot press-formed member and the blanking property of the material (base steel plate) are significantly reduced. Therefore, the C content is preferably 0.15% or more and 0.50% or less, and more preferably 0.20% or more and 0.40% or less.
《Si：0.05%以上2.00%以下》
SiはCと同様に鋼の強度を向上させる元素であり、熱間プレス成形部材の高強度化のためにはその量を0.05%以上とすることが好ましい。一方、Si量が2.00%を超えると、素地鋼板を製造する際、熱間圧延時に赤スケールと呼ばれる表面欠陥の発生が著しく増大する。したがって、Si含有量は0.05%以上2.00%以下とすることが好ましく、0.10%以上1.50%以下とすることがより好ましい。
<< Si: 0.05% or more and 2.00% or less >>
Si, like C, is an element that improves the strength of steel, and the amount is preferably 0.05% or more in order to increase the strength of the hot press-formed member. On the other hand, when the Si content exceeds 2.00%, the occurrence of surface defects called red scale during hot rolling significantly increases during the production of the base steel sheet. Therefore, the Si content is preferably 0.05% or more and 2.00% or less, and more preferably 0.10% or more and 1.50% or less.
《Mn：0.50%以上3.00%》
Mnは鋼の焼入れ性を高める元素であり、熱間プレス成形後の冷却過程で素地鋼板のフェライト変態を抑制して焼き入れ性を向上させるのに効果的な元素である。また、MnはAc3変態点を低下させる作用を有するため、熱間プレス成形前の表面処理鋼板１の加熱温度を低温下するのに有効な元素である。このような効果の発現のためには、Mn含有量を0.50%以上とすることが好ましい。一方、Mn量が3.00%を超えると、Mnが偏析して素地鋼板および熱間プレス成形部材の特性の均一性が低下する。したがってMn含有量は0.50%以上3.00%以下とすることが好ましく、0.75%以上2.50%以下とすることがより好ましい。
《Mn: 0.50% to 3.00%》
Mn is an element that enhances the hardenability of the steel, and is an effective element for improving the hardenability by suppressing the ferrite transformation of the base steel sheet during the cooling process after hot press forming. Further, Mn is an element effective for lowering the heating temperature of the surface-treated steel sheet 1 before hot press forming because it has an action of lowering the Ac3 transformation point. In order to exhibit such an effect, the Mn content is preferably 0.50% or more. On the other hand, when the amount of Mn exceeds 3.00%, Mn is segregated and the uniformity of the properties of the base steel sheet and the hot press-formed member decreases. Therefore, the Mn content is preferably 0.50% or more and 3.00% or less, and more preferably 0.75% or more and 2.50% or less.
《P：0.10%以下》
P含有量が0.10%を超えると、Pが粒界に偏析して素地鋼板および熱間プレス成形部材の低温靭性が低下する。したがって、P含有量は0.10%以下とすることが好ましく、0.01%以下とすることがより好ましい。
<< P: 0.10% or less >>
When the P content exceeds 0.10%, P is segregated at the grain boundaries, and the low temperature toughness of the base steel sheet and the hot press-formed member decreases. Therefore, the P content is preferably 0.10% or less, and more preferably 0.01% or less.
《S：0.050%以下》
SはMnと結合して粗大な硫化物を形成し、鋼の延性低下を招く元素である。そのため、S含有量は極力低減することが好ましいが、0.050%までは許容できる。したがって、S含有量は0.050%以下とすることが好ましく、0.010%以下とすることがより好ましい。
<< S: 0.050% or less >>
S is an element that combines with Mn to form coarse sulfides and causes a reduction in the ductility of the steel. Therefore, it is preferable to reduce the S content as much as possible, but it is acceptable up to 0.050%. Therefore, the S content is preferably 0.050% or less, and more preferably 0.010% or less.
《Al：0.10%以下》
Al含有量が0.10%を超えると酸化物系介在物の増加を招き、鋼の延性が低下する。したがって、Al含有量は0.10%以下とすることが好ましく、0.07%以下とすることがより好ましい。但し、Alは脱酸材としての作用を有し、鋼の清浄度向上の観点からは、その含有量を0.01%以上とすることが好ましい。
<Al: 0.10% or less>
If the Al content exceeds 0.10%, the oxide inclusions increase and the ductility of the steel decreases. Therefore, the Al content is preferably 0.10% or less, and more preferably 0.07% or less. However, Al has an action as a deoxidizing material, and from the viewpoint of improving the cleanliness of the steel, its content is preferably 0.01% or more.
《N：0.010%以下》
N含有量が0.010%を超えると、素地鋼板中にAlN等の窒化物が形成され、熱間プレス成形時の成形性の低下を招く。したがって、N含有量は0.010%以下とすることが好ましく、0.005%以下とすることがより好ましい。
<N: 0.010% or less>
When the N content exceeds 0.010%, a nitride such as AlN is formed in the base steel sheet, resulting in a decrease in formability during hot press forming. Therefore, the N content is preferably 0.010% or less, and more preferably 0.005% or less.
以上が本発明における素地鋼板の好ましい基本成分であるが、該素地鋼板は必要に応じて更に以下の元素を含有してもよい。
Cr：0.01%以上0.50%以下、V：0.01%以上0.50%以下、Mo：0.01%以上0.50%以下、Ni：0.01以上0.50%以下のうちの少なくとも１種以上。
Cr、V、Mo、Niはいずれも鋼の焼き入れ性を向上させるのに有効な元素である。この効果は、いずれの元素の場合も含有量を0.01%以上とすることにより得られる。しかし、Cr、V、Mo、Niはいずれも含有量が0.50％を超えると上記効果は飽和し、コストアップの要因となる。したがって、Cr、V、Mo、Niのいずれか1種以上を含有する場合には、それぞれ含有量を0.01%以上0.50%以下とすることが好ましく、0.10%以上0.40%以下とすることがより好ましい。
Although the above is a preferable basic component of the base steel plate in this invention, this base steel plate may contain the following elements further as needed.
Cr: 0.01% or more and 0.50% or less, V: 0.01% or more and 0.50% or less, Mo: 0.01% or more and 0.50% or less, Ni: 0.01 or more and 0.50% or less.
Cr, V, Mo, and Ni are all effective elements for improving the hardenability of steel. This effect can be obtained by setting the content to 0.01% or more for any element. However, if the Cr, V, Mo, and Ni content exceeds 0.50%, the above effect is saturated, which increases the cost. Therefore, when containing one or more of Cr, V, Mo, Ni, the content is preferably 0.01% or more and 0.50% or less, more preferably 0.10% or more and 0.40% or less .
Ti：0.01%以上0.20%以下
Tiは鋼の強化に有効である。Tiによる強度上昇効果は、その含有量を0.01%以上とすることで得られ、本発明で規定した範囲内であれば、鋼の強化に使用して差し支えない。しかし、含有量が0.20%を超えるとその効果は飽和し、コストアップの要因となる。従って、Tiを含有する場合には0.01%以上0.20%以下とすることが好ましく、0.01%以上0.05%以下とすることがより好ましい。
Ti: 0.01% or more and 0.20% or less
Ti is effective for strengthening steel. The effect of increasing the strength by Ti is obtained by setting its content to 0.01% or more. If it is within the range specified in the present invention, it can be used for strengthening steel. However, if the content exceeds 0.20%, the effect is saturated, which increases the cost. Therefore, when Ti is contained, it is preferably 0.01% or more and 0.20% or less, and more preferably 0.01% or more and 0.05% or less.
Nb：0.01%以上0.10%以下
Nbも鋼の強化に有効である。Nbによる強度上昇効果は、その含有量を0.01%以上とすることで得られ、本発明で規定した範囲内であれば、鋼の強化に使用して差し支えない。しかし、含有量が0.10%を超えるとその効果は飽和し、コストアップの要因となる。従って、Nbを含有する場合には0.01%以上0.10%以下とすることが好ましく、0.01%以上0.05%以下とすることがより好ましい。
Nb: 0.01% or more and 0.10% or less
Nb is also effective for strengthening steel. The effect of increasing the strength by Nb can be obtained by setting its content to 0.01% or more, and can be used for strengthening steel as long as it is within the range specified in the present invention. However, if the content exceeds 0.10%, the effect is saturated, which increases the cost. Therefore, when Nb is contained, it is preferably 0.01% or more and 0.10% or less, and more preferably 0.01% or more and 0.05% or less.
B：0.0002%以上0.0050%以下
Bは鋼の焼入れ性を高める元素であり、熱間プレス成形後に素地鋼板が冷却される際、オーステナイト粒界からのフェライトの生成を抑制して焼入れ組織を得るのに有効な元素である。その効果はB含有量を0.0002%以上で得られるが、0.0050%を超えるとその効果は飽和し、コストアップの要因となる。したがって、Bを含有する場合には、その含有量を0.0002%以上0.0050%以下とすることが好ましい。より好ましくは0.0005%以上0.0030%以下である。
B: 0.0002% or more and 0.0050% or less
B is an element that enhances the hardenability of the steel, and is an element effective for obtaining a quenched structure by suppressing the formation of ferrite from the austenite grain boundaries when the base steel sheet is cooled after hot press forming. The effect can be obtained when the B content is 0.0002% or more. However, if the B content exceeds 0.0050%, the effect is saturated, resulting in a cost increase. Therefore, when B is contained, the content is preferably 0.0002% or more and 0.0050% or less. More preferably, it is 0.0005% or more and 0.0030% or less.
Sb：0.003%以上0.030%以下
Sbは熱間プレス成形前に鋼板を加熱してから熱間プレス成形の一連の処理によって鋼板を冷却するまでの間に、素地鋼板表層部に生じる脱炭層を抑制する効果を有する。このような効果の発現のためには、Sb含有量を0.003%以上とすることが好ましい。しかし、Sb含有量が0.030%を超えると素地鋼板製造時に圧延荷重の増大を招き、生産性の低下が懸念される。したがって、Sbを含有する場合には、その含有量を0.003%以上0.030%以下とすることが好ましく、0.005%以上0.010%以下とすることがより好ましい。
Sb: 0.003% to 0.030%
Sb has an effect of suppressing a decarburized layer generated in the surface layer portion of the base steel sheet after the steel sheet is heated before hot press forming and before the steel plate is cooled by a series of processes of hot press forming. In order to exhibit such an effect, the Sb content is preferably 0.003% or more. However, if the Sb content exceeds 0.030%, the rolling load increases during the production of the base steel sheet, and there is a concern that the productivity may be reduced. Therefore, when Sb is contained, the content is preferably 0.003% or more and 0.030% or less, and more preferably 0.005% or more and 0.010% or less.
なお、上記成分以外の成分(残部)はFeおよび不可避的不純物である。 Components other than the above components (remainder) are Fe and inevitable impurities.
本発明において熱間プレス成形部材の素材として用いる表面処理鋼板１は、その製造条件に特段の制限はない。素地鋼板の製造条件は特に限定されず、例えば所定の成分組成を有する熱延鋼板（酸洗鋼板）や熱延鋼板に冷間圧延を施すことにより得られる冷延鋼板を素地鋼板としても良い。
素地鋼板の表面に、Zn-Niめっき層を形成して表面処理鋼板１とする際の条件も、特に限定されない。素地鋼板として熱延鋼板（酸洗鋼板）を用いる場合には、熱延鋼板（酸洗鋼板）にZn-Niめっき処理を施すことにより、表面処理鋼板１とすることができる。
In the present invention, the surface-treated steel sheet 1 used as a raw material of the hot press-formed member is not particularly limited in its production conditions. The production conditions of the base steel sheet are not particularly limited. For example, a hot-rolled steel sheet (pickled steel sheet) having a predetermined composition and a cold-rolled steel sheet obtained by cold rolling a hot-rolled steel sheet may be used as the base steel sheet.
The conditions for forming the Zn-Ni plating layer on the surface of the base steel sheet to form the surface-treated steel sheet 1 are not particularly limited. When a hot-rolled steel plate (pickled steel plate) is used as the base steel plate, the surface-treated steel plate 1 can be obtained by subjecting the hot-rolled steel plate (pickled steel plate) to a Zn—Ni plating treatment.
一方、素地鋼板として冷延鋼板を用いる場合には、冷間圧延後そのまま、あるいは焼鈍処理を行った後、Zn-Niめっき処理を施すことにより、表面処理鋼板１とすることができる。 On the other hand, when a cold-rolled steel sheet is used as the base steel sheet, the surface-treated steel sheet 1 can be obtained by performing a Zn-Ni plating process as it is after cold rolling or after annealing.
素地鋼板表面にZn-Niめっき層を形成する場合、例えば、素地鋼板を、脱脂、酸洗した後、100g/L以上400g/L以下の硫酸ニッケル六水和物、10g/L以上400g/L以下の硫酸亜鉛七水和物を含有するpH1.0以上3.0以下、浴温30℃以上70℃以下のめっき浴中で、10A/dm2以上150A/dm2以下の電流密度で電気めっき処理を行うことにより、Zn-Niめっき層を形成することができる。なお、素地鋼板として冷延鋼板を用いる場合には、上記脱脂、酸洗に先立ち、冷延鋼板に焼鈍処理を施してもよい。めっき層中のNi含有量は、硫酸亜鉛七水和物の濃度や電流密度を上記の範囲内で適宜調整することにより、所望のNi含有量（例えば、9質量%以上25質量%以下）とすることができる。また、Zn-Niめっき層の付着量は、通電時間を調整することにより、所望の付着量（例えば、片面あたり10g/m2以上90g/m2以下）とすることができる。 When forming a Zn-Ni plating layer on the base steel plate surface, for example, after degreasing and pickling the base steel plate, nickel sulfate hexahydrate of 100 g / L to 400 g / L, 10 g / L to 400 g / L Perform electroplating at a current density of 10A / dm2 or more and 150A / dm2 or less in a plating bath containing the following zinc sulfate heptahydrate, pH 1.0 to 3.0 and bath temperature 30 ° C to 70 ° C. Thus, a Zn—Ni plating layer can be formed. In addition, when using a cold-rolled steel plate as a base steel plate, you may anneal a cold-rolled steel plate prior to the said degreasing | defatting and pickling. The Ni content in the plating layer can be adjusted to the desired Ni content (for example, 9% by mass to 25% by mass) by appropriately adjusting the concentration and current density of zinc sulfate heptahydrate within the above ranges. can do. Moreover, the adhesion amount of the Zn—Ni plating layer can be set to a desired adhesion amount (for example, 10 g / m 2 or more and 90 g / m 2 or less per side) by adjusting the energization time.
本発明に係る熱間プレス成形品の製造方法の効果を確認する実験を行ったので、以下これについて説明する。
表1に示す成分を有する鋼を溶製して鋳片として、該鋳片を1200℃に加熱し、870℃の仕上げ圧延終了温度で熱間圧延を施した後、600℃で巻き取り、熱延鋼板とした。
Since an experiment for confirming the effect of the method for producing a hot press-formed product according to the present invention was conducted, this will be described below.
As a slab by melting steel having the components shown in Table 1, the slab is heated to 1200 ° C, subjected to hot rolling at a finish rolling finish temperature of 870 ° C, and then wound up at 600 ° C and heated. A rolled steel sheet was used.
次いで、該熱延鋼板を酸洗後50%の圧下率で冷間圧延し、板厚1.6mmの冷延鋼板とした。表1に記載のAc3変態点は、以下の（１）式より算出した（William C.Leslie著、幸田成康監訳、熊井浩、野田龍彦訳、「レスリー鉄鋼材料学」、丸善株式会社、1985年、p.273参照）。
Ac3（℃）=910-203√[C]+44.7×[Si]-30×[Mn]+700×[P]+400×[Al] ・・・（１）
なお、（１）式において、[C]、[Si]、[Mn]、[P]、[Al]は、各元素（C、Si、Mn、P、Al）の含有%（質量%）である。
以上のようにして得られた冷延鋼板を素地鋼板とし、素地鋼板の表面に、純Znめっき層、Zn-Feめっき層、Zn-Niめっき層の各めっき層を形成して表面処理鋼板１とした。各めっき層は、以下の条件で形成した。
Next, the hot-rolled steel sheet was pickled and cold-rolled at a reduction rate of 50% to obtain a cold-rolled steel sheet having a thickness of 1.6 mm. The Ac3 transformation point shown in Table 1 was calculated from the following formula (1) (William C. Leslie, translated by Kouda Shigeyasu, Kumai Hiroshi, Noda Tatsuhiko, Leslie Steel Materials Science, Maruzen Corporation, 1985 , P.273).
Ac3 (℃) = 910-203√ [C] + 44.7 × [Si] -30 × [Mn] + 700 × [P] + 400 × [Al] (1)
In the formula (1), [C], [Si], [Mn], [P], and [Al] are the content% (mass%) of each element (C, Si, Mn, P, Al). is there.
The cold-rolled steel sheet obtained as described above is used as a base steel sheet, and a surface-treated steel sheet 1 is formed by forming each of the pure Zn plating layer, Zn-Fe plating layer, and Zn-Ni plating layer on the surface of the base steel plate. It was. Each plating layer was formed under the following conditions.
＜純Znめっき層＞
冷延鋼板を連続溶融亜鉛めっきラインに通板し、10℃/sの昇温速度で800℃以上900℃以下の温度域まで加熱し、該温度域に10s以上120s以下滞留させた後、15℃/sの冷却速度で460℃以上500℃以下の温度域まで冷却し、450℃の亜鉛めっき浴に浸漬することにより、Znめっき層を形成した。Znめっき層の付着量は、ガスワイピング法により所定の付着量に調整した。
<Pure Zn plating layer>
The cold-rolled steel sheet is passed through a continuous hot-dip galvanizing line, heated to a temperature range of 800 ° C. or higher and 900 ° C. or lower at a temperature increase rate of 10 ° C./s. The Zn plating layer was formed by cooling to a temperature range of 460 ° C. or more and 500 ° C. or less at a cooling rate of ° C./s and dipping in a 450 ° C. zinc plating bath. The adhesion amount of the Zn plating layer was adjusted to a predetermined adhesion amount by a gas wiping method.
＜Zn-Feめっき層＞
冷延鋼板を連続溶融亜鉛めっきラインに通板し、10℃/sの昇温速度で800℃以上900℃以下の温度域まで加熱し、該温度域に10s以上120s以下滞留させた後、15℃/sの冷却速度で460℃以上500℃以下の温度域まで冷却し、450℃の亜鉛めっき浴に浸漬することにより、Znめっき層を形成した。Znめっき層の付着量は、ガスワイピング法により所定の付着量に調整した。ガスワイピング法により所定の付着量に調整した後、直ちに合金化炉で500〜550℃に加熱して5〜60s保持することにより、Zn-Feめっき層を形成した。めっき層中のFe含有量は、合金化炉での加熱温度や該加熱温度での滞留時間を上記の範囲内で変更することにより、所定の含有量とした。
<Zn-Fe plating layer>
The cold-rolled steel sheet is passed through a continuous hot-dip galvanizing line, heated to a temperature range of 800 ° C. or higher and 900 ° C. or lower at a temperature increase rate of 10 ° C./s. The Zn plating layer was formed by cooling to a temperature range of 460 ° C. or more and 500 ° C. or less at a cooling rate of ° C./s and dipping in a 450 ° C. zinc plating bath. The adhesion amount of the Zn plating layer was adjusted to a predetermined adhesion amount by a gas wiping method. After adjusting to a predetermined adhesion amount by a gas wiping method, the Zn—Fe plating layer was formed by immediately heating to 500 to 550 ° C. in an alloying furnace and holding for 5 to 60 s. The Fe content in the plating layer was set to a predetermined content by changing the heating temperature in the alloying furnace and the residence time at the heating temperature within the above range.
＜Zn-Niめっき層＞
冷延鋼板を連続焼鈍ラインに通板し、10℃/sの昇温速度で800℃以上900℃以下の温度域まで加熱し、該温度域に10ｓ以上120ｓ以下滞留させた後、15℃/sの冷却速度で500℃以下の温度域まで冷却した。次いで、脱脂、酸洗した後、200g/Lの硫酸ニッケル六水和物、10〜300g/Lの硫酸亜鉛七水和物を含有するpH1.3、浴温50℃のめっき浴中、30〜100A/dm2の電流密度で10〜100s通電する電気めっき処理を行うことにより、Zn-Niめっき層を形成した。めっき層中のNi含有量は、硫酸亜鉛七水和物の濃度や電流密度を上記の範囲内で適宜調整することにより、所定の含有量とした。また、Zn-Niめっき層の付着量は、通電時間を上記の範囲内で適宜調整することにより、所定の付着量とした。
<Zn-Ni plating layer>
The cold-rolled steel sheet is passed through a continuous annealing line, heated to a temperature range of 800 ° C to 900 ° C at a rate of 10 ° C / s, and retained in the temperature range for 10s to 120s, then 15 ° C / s It cooled to the temperature range below 500 degreeC with the cooling rate of s. Next, after degreasing and pickling, in a plating bath containing 200 g / L nickel sulfate hexahydrate, 10 to 300 g / L zinc sulfate heptahydrate pH 1.3, bath temperature 50 ° C., 30 to A Zn-Ni plating layer was formed by performing an electroplating process in which a current of 10 to 100 s was applied at a current density of 100 A / dm2. The Ni content in the plating layer was set to a predetermined content by appropriately adjusting the concentration and current density of zinc sulfate heptahydrate within the above ranges. Moreover, the adhesion amount of the Zn—Ni plating layer was set to a predetermined adhesion amount by appropriately adjusting the energization time within the above range.
以上のようにして得られた表面処理鋼板から、200mm×400mmのブランク板を打抜き、該ブランク板を大気雰囲気の電気炉により加熱したのち、ブランク板を金型（材料：SKD61）に設置し、その後に金型による冷却およびプレス成形を行った。そして、金型内で焼入れた後、離型することにより、図１１に示すハット形状のプレス成形部材を製造した。金型の形状は、パンチ肩R：6mm、ダイ肩R：6mmの金型を用い、パンチ-ダイのクリアランス：1.6mmとした。プレス成形前の表面処理鋼板の冷却は冷却用金型との接触で行った。プレス成形は、98ｋNのしわ押さえ力をかけたまま成形するドロー成形と、しわ押さえ無しで成形するフォーム成形にて行った。 From the surface-treated steel plate obtained as described above, a blank plate of 200 mm × 400 mm is punched, and after the blank plate is heated by an electric furnace in an air atmosphere, the blank plate is placed in a mold (material: SKD61), Thereafter, cooling with a mold and press molding were performed. And after quenching in a metal mold | die, the hat-shaped press molding member shown in FIG. 11 was manufactured by releasing. The molds were punch punch R: 6 mm and die shoulder R: 6 mm, and the punch-die clearance was 1.6 mm. The surface-treated steel sheet before press forming was cooled by contact with a cooling mold. The press molding was performed by a draw molding in which a 98 kN wrinkle pressing force was applied and a foam molding in which no wrinkle pressing was performed.
ブランク板の加熱温度、素地鋼板の種類、めっき層の種類、加熱条件、プレス前冷却条件、プレス条件、プレス後サンプルの状態を表２に示す。 Table 2 shows the heating temperature of the blank plate, the type of the base steel plate, the type of the plating layer, the heating condition, the cooling condition before pressing, the pressing condition, and the state of the sample after pressing.
得られたハット形状のプレス成形部材の縦壁部からサンプルを採取し、その表面の断面を、走査型電子顕微鏡（SEM）を用いて倍率1000倍で各サンプルにつき10視野観察し、ミクロクラック（サンプル表面に生じる微小割れであって、めっき層-素地鋼板の界面を貫通して素地鋼板内部に至る微小割れ）の有無、およびミクロクラックの平均深さを調べた。ミクロクラックの平均深さは、任意のミクロクラック20個分のミクロクラック深さの平均値として求めた。なお、ここでいう「ミクロクラック深さ」とは、図１２に示すようにミクロクラック２１の、めっき層２３と素地鋼板２５の界面から測定される板厚中央方向への割れの長さ（図１２中、hの長さ）を意味する。観察されるミクロクラックの個数が20個未満である場合には、観察される全てのミクロクラック深さの平均深さとした。
また、得られたプレス成形部材の形状精度について図１３に示すハット部材の離型後の成形品幅Ｗと金型形状での成形品幅Ｗ０の差（Ｗ−Ｗ０）を口開き量として評価した。その結果も併せて表２に示してある。
Samples were taken from the vertical wall portion of the obtained hat-shaped press-molded member, and the cross-section of the surface was observed with 10 fields of view for each sample at a magnification of 1000 using a scanning electron microscope (SEM). The presence or absence of microcracks that occurred on the sample surface and penetrated the interface between the plating layer and the base steel sheet and reached the inside of the base steel sheet, and the average depth of the microcracks were examined. The average depth of microcracks was determined as the average value of the depth of microcracks for 20 arbitrary microcracks. As used herein, “microcrack depth” refers to the length of the crack in the center direction of the thickness of the microcrack 21 measured from the interface between the plating layer 23 and the base steel plate 25 (see FIG. 12). 12, the length of h). When the number of observed microcracks was less than 20, the average depth of all the observed microcracks was taken.
Further, regarding the shape accuracy of the obtained press-molded member, the difference (W−W 0 ) between the molded product width W after release of the hat member shown in FIG. 13 and the molded product width W 0 in the mold shape is shown in FIG. As evaluated. The results are also shown in Table 2.
発明例１〜７、８〜９において、めっき層の種類（Zn-Niめっき層）、冷却方法（金型冷却）、冷却時間（0.6s〜1.7s）、冷却速度（発明範囲：100℃/s以上）、および冷却停止温度（発明範囲：410℃〜550℃）、冷却後プレス成形開始までの時間（発明範囲：５秒）、プレス成形開始温度（発明範囲400℃〜550℃）は、すべて本発明の範囲内にある。プレス後サンプルには、ミクロクラックは発生せず、口開き量も0mmであった。これにより、本発明範囲内のプレス成形方法では、良好な形状凍結性を確保しつつ、ミクロクラックの生成を抑制することが可能であると実証された。 In Invention Examples 1 to 7 and 8 to 9, the type of the plating layer (Zn—Ni plating layer), the cooling method (mold cooling), the cooling time (0.6 s to 1.7 s), the cooling rate (invention range: 100 ° C. / s) or more, and the cooling stop temperature (invention range: 410 ° C. to 550 ° C.), the time until the start of press molding after cooling (invention range: 5 seconds), the press molding start temperature (invention range 400 ° C. to 550 ° C.), All are within the scope of the present invention. The sample after pressing had no microcracks and the opening amount was 0 mm. As a result, it was demonstrated that the press molding method within the scope of the present invention can suppress the generation of microcracks while ensuring good shape freezing property.
比較例１において、めっき層の種類（Zn-Niめっき層）は本発明と同じであるが、冷却用金型で冷却することなく成形を行ったものである。また、比較例２〜４は、めっき層の種類はZn-Niめっき層であるが、冷却停止温度（発明範囲：410℃〜550℃）が本発明範囲外のものである。具体的には、比較例２の冷却停止温度が600℃、比較例３、４の冷却停止温度が340℃、290℃である。 In Comparative Example 1, the type of the plating layer (Zn—Ni plating layer) is the same as that of the present invention, but is formed without cooling with a cooling mold. In Comparative Examples 2 to 4, the type of the plating layer is a Zn—Ni plating layer, but the cooling stop temperature (invention range: 410 ° C. to 550 ° C.) is outside the range of the present invention. Specifically, the cooling stop temperature of Comparative Example 2 is 600 ° C., and the cooling stop temperatures of Comparative Examples 3 and 4 are 340 ° C. and 290 ° C.
比較例１、２のプレス成形後のサンプルをみると、口開き量は0mmであるが、ミクロクラックが発生している。これにより、鋼板の成形開始温度が550℃より高い場合には、ミクロクラックが発生することが実証された。
比較例３、４をみると、ミクロクラックは発生していないが、口開き量が8mm〜9mmである。これにより、冷却時間が長すぎて鋼板の冷却停止温度が410℃未満となった場合には、プレス成形開始温度が400℃未満となるため、鋼板の強度が上昇して、形状凍結性の低下が起こることが実証された。
When the samples after press molding of Comparative Examples 1 and 2 are viewed, the opening amount is 0 mm, but microcracks are generated. As a result, it was proved that microcracks occur when the forming start temperature of the steel sheet is higher than 550 ° C.
In Comparative Examples 3 and 4, no microcracks are generated, but the amount of opening is 8 mm to 9 mm. As a result, if the cooling time is too long and the cooling stop temperature of the steel sheet is less than 410 ° C, the press forming start temperature is less than 400 ° C, so the strength of the steel sheet increases and the shape freezeability decreases. Has been demonstrated to occur.
比較例５〜７において、めっき層の種類（Zn-Niめっき層）は本発明と同じであるが、冷却方法がガス冷却であることで、冷却速度が本発明範囲内（100℃/s以上）とならず、急速冷却することができない。そのため、比較例５、６では鋼板の冷却停止温度及びプレス成形開始温度が発明範囲外（550℃超）であり、ミクロクラックが発生する。また、比較例７では、冷却停止温度が510℃であり本発明範囲内となるが、口開き量が3mmと形状凍結性の低下が生じている。これは、ガス冷却のため冷却時間が長くて冷却速度が遅くなり、角度変化が生じたものと考えられる。
さらに、比較例６、７ではガス冷却である程度まで緩冷却しプレスした後での焼入れとなったため、プレス成形後の硬度が低下している。
In Comparative Examples 5 to 7, the type of the plating layer (Zn—Ni plating layer) is the same as that of the present invention, but the cooling method is gas cooling, so that the cooling rate is within the range of the present invention (100 ° C./s or more). ) And cannot be rapidly cooled. Therefore, in Comparative Examples 5 and 6, the steel sheet cooling stop temperature and press forming start temperature are outside the range of the invention (above 550 ° C.), and microcracks are generated. Further, in Comparative Example 7, the cooling stop temperature is 510 ° C., which is within the range of the present invention, but the shape openability is reduced to 3 mm and the shape freezeability is reduced. This is considered to be because the cooling time was slow due to gas cooling, the cooling rate was slow, and the angle change occurred.
Furthermore, in Comparative Examples 6 and 7, since the quenching was performed after the gas was cooled to a certain degree and then cooled and pressed, the hardness after press molding was lowered.
比較例８、９において、冷却方法（金型冷却）、冷却速度（180℃/s、153℃/s）、冷却停止温度（530℃、440℃）、プレス成形開始温度（505℃、420℃）、は本発明の範囲内であるが、プレス成形開始までの時間がそれぞれ10秒、8秒と本発明の5秒以内よりも長時間になっている。そのため、プレス成形後のサンプルをみると、口開き量が2mm、と硬度の低下（365Hv、382Hv）が発生している。 In Comparative Examples 8 and 9, cooling method (mold cooling), cooling rate (180 ° C / s, 153 ° C / s), cooling stop temperature (530 ° C, 440 ° C), press molding start temperature (505 ° C, 420 ° C) ) Is within the scope of the present invention, but the time until the start of press molding is 10 seconds and 8 seconds, respectively, which is longer than 5 seconds of the present invention. Therefore, looking at the sample after press molding, the opening amount is 2 mm, and the hardness is reduced (365Hv, 382Hv).
比較例１０、１１において、冷却方法（金型冷却）、冷却速度（167℃/s、190℃/s）、冷却停止温度（500℃、530℃）、プレス成形開始までの時間（2S）、プレス成形開始温度（495℃、525℃）は本発明範囲内であるが、めっき層の種類が異なる。比較例１０はZnのみ、比較例１１はZn-Feのめっき層である。そのため、プレス後サンプルをみると、ミクロクラックが発生している。 In Comparative Examples 10 and 11, the cooling method (mold cooling), the cooling rate (167 ° C./s, 190 ° C./s), the cooling stop temperature (500 ° C., 530 ° C.), the time until the start of press molding (2S), The press molding start temperature (495 ° C., 525 ° C.) is within the scope of the present invention, but the type of the plating layer is different. Comparative Example 10 is only Zn, and Comparative Example 11 is a Zn—Fe plating layer. For this reason, microcracks are generated in the sample after pressing.
１ 表面処理鋼板
３ 冷却用金型
５ 上金型
７ 下金型
９ リフターピン
１１ プレス成形金型
１３ ダイ
１５ ブランクホルダ
１７ パンチ
１９ 熱電対
２１ ミクロクラック
２３ めっき層
２５ 素地鋼板
DESCRIPTION OF SYMBOLS 1 Surface treatment steel plate 3 Cooling die 5 Upper die 7 Lower die 9 Lifter pin 11 Press molding die 13 Die 15 Blank holder 17 Punch 19 Thermocouple 21 Micro crack 23 Plating layer 25 Base steel plate
Claims (1)
Ac3変態点以上で1000℃以下の温度域に加熱した前記表面処理鋼板の全面を、前記表面処理鋼板との接触面が平面である冷却用金型を用いて、前記表面処理鋼板が800℃以下670℃以上になっているタイミングで、100℃/s以上の冷却速度で550℃以下410℃以上の温度まで冷却する冷却工程と、
冷却後5秒以内にプレス成形金型を用いて鋼板温度が550℃以下400℃以上の範囲内でプレス成形を開始するプレス成形工程と、
前記表面処理鋼板を前記プレス成形金型で挟んだまま保持して前記表面処理鋼板を焼入れる焼入れ工程とを備え、
Zn-Niめっき層−地鉄界面から地鉄内部方向への深さが約30μm以下であってミクロクラックと称する微小割れの発生を防止することを特徴とする熱間プレス成形品の製造方法。 A hot press-formed product manufacturing method for manufacturing a hot press-formed product by hot-pressing a surface-treated steel sheet having a Zn-Ni plating layer formed on the surface of a base steel plate,
The entire surface of the surface-treated steel sheet heated to a temperature range of 1000 ° C. or more above the Ac3 transformation point, using a cooling mold having a flat contact surface with the surface-treated steel sheet, the surface-treated steel sheet is 800 ° C. or less. at a timing that is a 670 ° C. or higher, a cooling step of cooling at 100 ° C. / s or more cooling rate until a temperature of 550 ° C. or less 410 ° C. or higher,
A press forming process in which press forming is started within a range of a steel sheet temperature of 550 ° C. or lower and 400 ° C. or higher using a press mold within 5 seconds after cooling;
Holding the surface-treated steel sheet sandwiched between the press-molding dies and quenching the surface-treated steel sheet,
A method for producing a hot press-formed product, characterized in that the depth from the Zn-Ni plating layer-base iron interface to the inside of the base iron is about 30 μm or less and the occurrence of microcracks called microcracks is prevented .
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| JP2014195530A JP6152836B2 (en) | 2014-09-25 | 2014-09-25 | Manufacturing method of hot press-formed product |
| US15/502,614 US20170225215A1 (en) | 2014-09-25 | 2015-09-07 | Method of manufacturing hot press-formed part, and hot press-formed part |
| CN201580049874.9A CN106714996B (en) | 2014-09-25 | 2015-09-07 | The manufacturing method of hot-forming product and hot-forming product |
| PCT/JP2015/004533 WO2016047058A1 (en) | 2014-09-25 | 2015-09-07 | Method of manufacturing hot press-formed product, and hot press-formed product |
| MX2017003875A MX2017003875A (en) | 2014-09-25 | 2015-09-07 | Method of manufacturing hot press-formed part, and hot press-formed part. |
| EP15843885.3A EP3199257B1 (en) | 2014-09-25 | 2015-09-07 | Method of manufacturing hot press-formed part, and hot press-formed part |
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| CN111936248B (en) * | 2018-04-13 | 2022-08-30 | 日本制铁株式会社 | Method for manufacturing hot press-molded product, die and die set |
| WO2020158285A1 (en) * | 2019-01-31 | 2020-08-06 | Ｊｆｅスチール株式会社 | Hot-pressed member, cold-rolled steel sheet for hot-pressed member, and methods respectively for producing these products |
| CN112139335B (en) * | 2020-09-09 | 2022-02-01 | 山东钢铁集团日照有限公司 | Preparation method of high-corrosion-resistance easy-to-weld hot-pressed part |
| US11441039B2 (en) * | 2020-12-18 | 2022-09-13 | GM Global Technology Operations LLC | High temperature coatings to mitigate weld cracking in resistance welding |
| CN114029699B (en) * | 2021-10-22 | 2022-08-30 | 广东中辉绿建移动房屋科技有限公司 | Preparation method of galvanized roof and integrated house roof |
Family Cites Families (21)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE435527B (en) * | 1973-11-06 | 1984-10-01 | Plannja Ab | PROCEDURE FOR PREPARING A PART OF Hardened Steel |
| GB1465209A (en) * | 1973-12-17 | 1977-02-23 | Upjohn Co | Clindamycin2-phosphates |
| FR2807447B1 (en) * | 2000-04-07 | 2002-10-11 | Usinor | METHOD FOR MAKING A PART WITH VERY HIGH MECHANICAL CHARACTERISTICS, SHAPED BY STAMPING, FROM A STRIP OF LAMINATED AND IN PARTICULAR HOT ROLLED AND COATED STEEL SHEET |
| JP3896061B2 (en) * | 2002-10-07 | 2007-03-22 | 新日本製鐵株式会社 | Steel sheet with excellent curability after hot forming and method of using the same |
| JP3816937B1 (en) * | 2005-03-31 | 2006-08-30 | 株式会社神戸製鋼所 | Steel sheet for hot-formed product, method for producing the same, and hot-formed product |
| JP4681492B2 (en) * | 2006-04-07 | 2011-05-11 | 新日本製鐵株式会社 | Steel plate hot pressing method and press-formed product |
| US7650547B2 (en) | 2007-02-28 | 2010-01-19 | Verigy (Singapore) Pte. Ltd. | Apparatus for locating a defect in a scan chain while testing digital logic |
| JP4825882B2 (en) * | 2009-02-03 | 2011-11-30 | トヨタ自動車株式会社 | High-strength quenched molded body and method for producing the same |
| PT2290133E (en) * | 2009-08-25 | 2012-06-19 | Thyssenkrupp Steel Europe Ag | Method for producing a steel component with an anti-corrosive metal coating and steel component |
| JP4849186B2 (en) * | 2009-10-28 | 2012-01-11 | Ｊｆｅスチール株式会社 | Hot pressed member and method for manufacturing the same |
| JP4883240B1 (en) * | 2010-08-04 | 2012-02-22 | Ｊｆｅスチール株式会社 | Steel sheet for hot press and method for producing hot press member using the same |
| ES2858225T3 (en) * | 2010-12-24 | 2021-09-29 | Voestalpine Stahl Gmbh | Procedure for producing tempered structural elements |
| DE102011053941B4 (en) * | 2011-09-26 | 2015-11-05 | Voestalpine Stahl Gmbh | Method for producing hardened components with regions of different hardness and / or ductility |
| DE102011053939B4 (en) * | 2011-09-26 | 2015-10-29 | Voestalpine Stahl Gmbh | Method for producing hardened components |
| WO2012097976A1 (en) * | 2011-01-17 | 2012-07-26 | Tata Steel Ijmuiden B.V. | Method to produce a hot formed part, and part thus formed |
| JP5817479B2 (en) * | 2011-03-10 | 2015-11-18 | Ｊｆｅスチール株式会社 | Manufacturing method of hot press member |
| EP2719788B1 (en) * | 2011-06-10 | 2016-11-02 | Kabushiki Kaisha Kobe Seiko Sho | Hot press molded article, method for producing same, and thin steel sheet for hot press molding |
| EP2752257B1 (en) * | 2011-09-01 | 2016-07-27 | Kabushiki Kaisha Kobe Seiko Sho | Hot-stamp molded part and method for manufacturing same |
| JP2013075329A (en) * | 2011-09-30 | 2013-04-25 | Kobe Steel Ltd | Method for manufacturing press-molded article and press molding equipment |
| WO2013132821A1 (en) * | 2012-03-06 | 2013-09-12 | Ｊｆｅスチール株式会社 | Warm press forming method and automobile frame component |
| JP5825413B1 (en) * | 2014-04-23 | 2015-12-02 | Ｊｆｅスチール株式会社 | Manufacturing method of hot press-formed product |
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| EP3199257A4 (en) | 2017-12-06 |
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| WO2016047058A8 (en) | 2017-01-19 |
| MX2017003875A (en) | 2017-06-08 |
| JP2016064440A (en) | 2016-04-28 |
| US20170225215A1 (en) | 2017-08-10 |
| CN106714996A (en) | 2017-05-24 |
| CN106714996B (en) | 2019-07-05 |
| EP3199257A1 (en) | 2017-08-02 |
| WO2016047058A1 (en) | 2016-03-31 |
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