WO2009113938A1 - A method of shaping and hardening a sheet steel blank - Google Patents

A method of shaping and hardening a sheet steel blank Download PDF

Info

Publication number
WO2009113938A1
WO2009113938A1 PCT/SE2009/000122 SE2009000122W WO2009113938A1 WO 2009113938 A1 WO2009113938 A1 WO 2009113938A1 SE 2009000122 W SE2009000122 W SE 2009000122W WO 2009113938 A1 WO2009113938 A1 WO 2009113938A1
Authority
WO
WIPO (PCT)
Prior art keywords
blank
product
sheet steel
dies
hardening
Prior art date
Application number
PCT/SE2009/000122
Other languages
French (fr)
Inventor
Katarina LINDSTRÖM
Daniel Berglund
Paul AKERSTRÖM
Original Assignee
Gestamp Hardtech Ab
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Gestamp Hardtech Ab filed Critical Gestamp Hardtech Ab
Publication of WO2009113938A1 publication Critical patent/WO2009113938A1/en

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D22/00—Shaping without cutting, by stamping, spinning, or deep-drawing
    • B21D22/02—Stamping using rigid devices or tools
    • 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
    • C21D1/02—Hardening articles or materials formed by forging or rolling, with no further heating beyond that required for the formation
    • 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
    • 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
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
    • 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
    • C21D9/48—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals deep-drawing sheets
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D11/00—Process control or regulation for heat treatments
    • C21D11/005—Process control or regulation for heat treatments for cooling
    • 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
    • C21D2221/00—Treating localised areas of an article

Definitions

  • the invention pertains to a method of shaping and hardening a sheet steel blank into a product by heating the blank to the austenite state and hot-shaping the blank in a cooled pair of dies and hardening the shaped product while it is still inside the pair of dies, wherein one cools a portion of the product at a reduced cooling rate so that this part does not obtain the same high proportion of martensite as the rest of the product.
  • WO 2006/038868 describes a way of using the press-hardening process to obtain soft regions by reducing the cooling rate in these regions so that they do not obtain the same high proportion of martensite as the rest of the product, while the product otherwise remains predominantly martensitic.
  • the press-hardening process normally makes use of boron steel and one achieves a tensile strength of 1500 MPa or higher.
  • One purpose of the invention is to use the press-hardening process to make a heat- shaped and hardened products of sheet steel which have soft portions with an elongation at rupture that is better then achieved heretofore.
  • a blank of annealed sheet It can be a blank of cold-rolled and recrystallisation-annealed or soft-annealed sheet.
  • the invention is defined by the patent claims.

Abstract

In the press-hardening process, if one wishes to have soft portions in the finished product and therefore reduces the cooling rate for these portions so that the material in these portions does not obtain the same high proportion of martensite as the rest of the product, one can improve the elongation at rupture in these soft portions by using annealed sheet steel as the starting blank, even though the hot shaping is done at a temperature in which the steel is austenitic.

Description

A method of shaping and hardening a sheet steel blank
Field of the invention
The invention pertains to a method of shaping and hardening a sheet steel blank into a product by heating the blank to the austenite state and hot-shaping the blank in a cooled pair of dies and hardening the shaped product while it is still inside the pair of dies, wherein one cools a portion of the product at a reduced cooling rate so that this part does not obtain the same high proportion of martensite as the rest of the product.
Background of the invention
WO 2006/038868 describes a way of using the press-hardening process to obtain soft regions by reducing the cooling rate in these regions so that they do not obtain the same high proportion of martensite as the rest of the product, while the product otherwise remains predominantly martensitic. One can reduce the cooling rate in these regions by having gaps between the pair of shaping dies and the shaped product. Alternatively, one can prevent quick cooling of these regions in other ways, for example, by heating a portion of the pair of dies while the rest of the pair of dies are cooled as usual. The press-hardening process normally makes use of boron steel and one achieves a tensile strength of 1500 MPa or higher. In the vehicle industry, when one uses press-hardened beams with relatively short soft sections in order to control the course of deformation during a collision, these regions will be exposed to large deformation. It is therefore important that the material in these regions have large elongation at rupture. In the press-hardening process, one heats up to the austenite state and gets the same result for the hardened material whether one uses a starting material that was annealed or not. Therefore, one uses the cheaper non- annealed material. Object of the invention and description of the invention
One purpose of the invention is to use the press-hardening process to make a heat- shaped and hardened products of sheet steel which have soft portions with an elongation at rupture that is better then achieved heretofore.
This is accomplished, according to the invention, by using a blank of annealed sheet. It can be a blank of cold-rolled and recrystallisation-annealed or soft-annealed sheet.
A soft portion of a finished product, which is cooled at a lower rate and thus do not obtain the same high proportion of martensite as the rest of the product, have a lower yield strength and a lower tensile strength whether the starting material is annealed or not. It has been found, surprisingly, that the elongation at rupture is better when annealed starting material is used, than non-annealed, even though the blank is heated during the process to the austenitisation temperature range and hot-shaped in the austenitic state. Preferably, one achieves the lower cooling rate by holding portions of the pair of dies at an elevated temperature, for example, by induction heating, but one can achieve the lower cooling rate in other ways, for example, by gaps between the pair of dies and the shaped product. The invention is defined by the patent claims.

Claims

Patent claims
1. Method of shaping and hardening a sheet steel blank into a product by heating the blank to the austenite state and hot-shaping the blank in a cooled pair of dies and hardening the shaped product while it is still inside the pair of dies, wherein one cools a portion of the product at a reduced cooling rate so that this portion does not obtain the same high proportion of martensite as the rest of the product, characterised in that one uses a blank of annealed sheet steel.
2. Method according to claim 1 , characterised in that one uses gaps between the pair of dies and the shaped product to reduce the cooling rate.
3. Method according to claim 1 , characterised in that one holds certain portions of the pair of dies at an elevated temperature to reduce the cooling rate of portions of the shaped product.
4. Method according to claim 3, characterised in that one uses induction heating to hold the elevated temperature.
5. Method according to any of the preceding claims, characterised in that one uses a blank of recrystallisation-annealed sheet steel.
6. Method according to any of the preceding claims, characterised in that one uses a blank of soft-annealed sheet steel.
7. Method according to any of the preceding claims, characterised in that one uses a blank of cold-rolled sheet.
PCT/SE2009/000122 2008-03-12 2009-03-05 A method of shaping and hardening a sheet steel blank WO2009113938A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE0800566-2 2008-03-12
SE0800566A SE532160C2 (en) 2008-03-12 2008-03-12 Ways to mold and harden a sheet metal

Publications (1)

Publication Number Publication Date
WO2009113938A1 true WO2009113938A1 (en) 2009-09-17

Family

ID=41065465

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE2009/000122 WO2009113938A1 (en) 2008-03-12 2009-03-05 A method of shaping and hardening a sheet steel blank

Country Status (2)

Country Link
SE (1) SE532160C2 (en)
WO (1) WO2009113938A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2497840A1 (en) 2011-03-10 2012-09-12 Schwartz, Eva Oven system for partially heating steel blanks
EP3360621A1 (en) * 2017-02-14 2018-08-15 Volkswagen Aktiengesellschaft Method for producing a thermoformed and press-hardened steel sheet component

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1642991A1 (en) * 2003-05-28 2006-04-05 Sumitomo Metal Industries, Ltd. Method for hot forming and hot formed member
WO2006038868A1 (en) * 2004-10-04 2006-04-13 Gestamp Hardtech Ab A method of hot stamping and hardening a metal sheet
US20070163683A1 (en) * 2004-02-13 2007-07-19 Audi Ag Method for producing a component by reshaping a plate, and device for carrying out said method

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1642991A1 (en) * 2003-05-28 2006-04-05 Sumitomo Metal Industries, Ltd. Method for hot forming and hot formed member
US20070163683A1 (en) * 2004-02-13 2007-07-19 Audi Ag Method for producing a component by reshaping a plate, and device for carrying out said method
WO2006038868A1 (en) * 2004-10-04 2006-04-13 Gestamp Hardtech Ab A method of hot stamping and hardening a metal sheet

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2497840A1 (en) 2011-03-10 2012-09-12 Schwartz, Eva Oven system for partially heating steel blanks
WO2012120123A1 (en) 2011-03-10 2012-09-13 Schwartz, Eva Furnace system for the controlled heat treatment of sheet metal components
US9493856B2 (en) 2011-03-10 2016-11-15 Schwartz Gmbh Furnace system for the controlled heat treatment of sheet metal components
EP3360621A1 (en) * 2017-02-14 2018-08-15 Volkswagen Aktiengesellschaft Method for producing a thermoformed and press-hardened steel sheet component

Also Published As

Publication number Publication date
SE532160C2 (en) 2009-11-03
SE0800566L (en) 2009-09-13

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