EP0748874A1 - Mehrphasiger Stahl, Erzeugung von Walzprodukten und Verwendung des Stahls - Google Patents

Mehrphasiger Stahl, Erzeugung von Walzprodukten und Verwendung des Stahls Download PDF

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Publication number
EP0748874A1
EP0748874A1 EP96107885A EP96107885A EP0748874A1 EP 0748874 A1 EP0748874 A1 EP 0748874A1 EP 96107885 A EP96107885 A EP 96107885A EP 96107885 A EP96107885 A EP 96107885A EP 0748874 A1 EP0748874 A1 EP 0748874A1
Authority
EP
European Patent Office
Prior art keywords
carbon
steel
temperature
vol
equ
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP96107885A
Other languages
German (de)
English (en)
French (fr)
Inventor
Bertram Ehrhardt
Thomas Heidelauf
Klaus-Peter Imlau
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Thyssen Stahl AG
Original Assignee
Thyssen Stahl AG
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
Priority claimed from DE19605697A external-priority patent/DE19605697C2/de
Application filed by Thyssen Stahl AG filed Critical Thyssen Stahl AG
Publication of EP0748874A1 publication Critical patent/EP0748874A1/de
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
    • C—CHEMISTRY; METALLURGY
    • 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
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/001—Austenite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/002—Bainite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/008—Martensite

Definitions

  • the invention relates to a multi-phase steel, a method for producing rolled products from this steel with up to 70 vol .-% polygonal-ferritic structure and its use.
  • the steel should have high strength, good cold formability and improved surface quality after the last hot working step.
  • Known steels with predominantly polygonal ferrite in the structure and martensite embedded therein consist of (in mass%) 0.03 to 0.12% C, up to 0.8% Si and 0.8 to 1.7% Mn (DE 29 24 340 C2) or 0.02 to 0.2% C, 0.05 to 2.0% Si, 0.5 to 2% Mn, 0.3 to 1.5% Cr and up to 1% Cu, Ni and Mo (EP 0 072 867 B1). Both steels are calmed with aluminum and contain soluble residual contents of less than 0.1% Al. Silicon in these steels promotes ferrite transformation. In combination with manganese and possibly chromium, pearlite formation is suppressed. This ensures the sufficient enrichment of carbon in the second phase and the Polygonal ferrite formation predominantly achieved in relation to the second phase.
  • a multi-phase steel with (in mass%) 0.12 to 0.3% carbon 1.2 to 3.5% manganese 1.1 to 2.2% aluminum less than 0.2% silicon Balance iron including unavoidable impurities such as phosphorus and sulfur, with a pearlite-free structure consisting of less than 70% by volume of soft polygonal ferrite and the rest of bainitic ferrite and more than 4% by volume, preferably up to 20% by volume, of carbon-enriched austenite as well as, if necessary, additionally smaller proportions of carbon-enriched martensite Aluminum in an amount of% by mass Al ⁇ 7.6 * C equ. - 0.36 contains with one carbon equivalent (C equ. ) 0.2 ⁇ C. equ. % C + 1/20% Mn + 1/20% Cr + 1/15% Mo ⁇ 0.325.
  • Such a steel surpasses the product Rm.
  • A5 known silicon alloyed dual-phase steels and after the hot forming has improved surface quality, such as z. B. is required for wheel disks of motor vehicles, which are generated by cold forming of the hot-rolled steel.
  • the following additional elements can be added to the steel up to the specified amounts (in mass%): up to 0.05% titanium up to 0.8% chromium up to 0.5% molybdenum up to 0.8% copper up to 0.5% nickel.
  • Such a steel alloyed with aluminum instead of silicon achieves a product R m ⁇ A 5 > 18,000 N / mm 2nd % , ie an elongation at break A 5 > 18000 / Rm in% with a tensile strength value of Rm up to 900 N / mm 2 .
  • Characteristic of the steel according to the invention is the aluminum content, which is considerably increased compared to known steels with 1.1-2.2%.
  • the silicon content was limited to less than 0.2% according to the invention.
  • Known steels of this type require silicon contents over 0.5%.
  • the steel alloyed with aluminum according to the invention has the aforementioned multi-phase structure with residual austenite and has excellent mechanical properties. Above all, the surface quality of the thermoformed product after the last thermoforming stage is much better than was previously known from silicon-alloyed steels. The formation of pearlite is significantly delayed compared to known steels and can be safely avoided if the claimed process parameters are observed.
  • the carbon content is within the usual range for generic steels.
  • Manganese is added in an amount of 1.2 to 3.5% to avoid pearlite formation. Manganese has a solidifying effect and increases the strength level. The contents of carbon and manganese are interchangeable under the aspects of pearlite avoidance and effects on ferrite formation within the framework set by the carbon equivalent.
  • the intersection of the carbon equivalent value and the corresponding aluminum value should lie in the shaded area in FIG. 1 in order to obtain a ferrite content below 70% by volume and residual austenite contents of over 4% by volume under large-scale production conditions.
  • titanium up to 0.05% ensures nitrogen removal and prevents the formation of elongated manganese sulfides.
  • Chromium in an amount of up to 0.8% can be added to improve the martensite resistance and to prevent pearlite formation.
  • molybdenum increases the range of successful cooling rates.
  • Copper and nickel in an amount of up to 0.5% each can help lower the transition temperature and prevent pearlite.
  • the hot rolling end temperature ET should be in the range of Ar3 - 50 ° C ⁇ ET ⁇ Ar3 + 100 ° C lie.
  • the cooling from the hot rolling end temperature to the reel temperature between 200 and 500 ° C is accelerated with a cooling rate of 15 to 70 K / s.
  • the process according to the invention can promote the formation of polygonal ferrite in the range from Ar3 to Ar3 - 200 ° C. by taking a cooling break of 2 to 30 s, in which the cooling rate is below 15 K / s.
  • Fig. 2 shows a schematic representation of the production of hot strip coupled with the cooling process of the steel according to the invention during and after hot rolling.
  • a steel A according to the invention of the composition according to Table 1 was hot-rolled to a final strip thickness of 3.7 mm with a hot-rolling final temperature of 855 ° C.
  • the steel according to the invention is particularly suitable for the production of cold-formed automotive structural elements, such as floor reinforcement elements, wishbones, or for wheel disks.
  • Table 1 C% Mn% Al% Si% Cu% Ni% Cr% P% S% N% A 0.216 1.38 1.83 0.06 0.57 0.27 0.52 0.010 ⁇ 0.001 0.0024 B * 0.21 1.50 0.057 1.48 ⁇ 0.01 0.01 0.02 ⁇ 0.005 0.004 0.006 * according to EP 0 586 704 A1

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)
  • Heat Treatment Of Sheet Steel (AREA)
  • Laminated Bodies (AREA)
EP96107885A 1995-06-16 1996-05-17 Mehrphasiger Stahl, Erzeugung von Walzprodukten und Verwendung des Stahls Withdrawn EP0748874A1 (de)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DE19521836 1995-06-16
DE19521836 1995-06-16
DE19605697 1996-02-16
DE19605697A DE19605697C2 (de) 1995-06-16 1996-02-16 Mehrphasiger Stahl, Erzeugung von Walzprodukten und Verwendung des Stahls

Publications (1)

Publication Number Publication Date
EP0748874A1 true EP0748874A1 (de) 1996-12-18

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ID=26016012

Family Applications (1)

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EP96107885A Withdrawn EP0748874A1 (de) 1995-06-16 1996-05-17 Mehrphasiger Stahl, Erzeugung von Walzprodukten und Verwendung des Stahls

Country Status (10)

Country Link
EP (1) EP0748874A1 (es)
CN (1) CN1190998A (es)
AR (1) AR002502A1 (es)
BR (1) BR9608969A (es)
CA (1) CA2224813A1 (es)
CZ (1) CZ402697A3 (es)
HU (1) HUP9801755A3 (es)
PL (1) PL324556A1 (es)
TR (1) TR199701721T1 (es)
WO (1) WO1997000331A1 (es)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2748033A1 (fr) * 1996-04-26 1997-10-31 Lorraine Laminage Procede de realisation d'une bande de tole d'acier laminee a chaud a tres haute resistance utilisable pour la mise en forme et notamment pour l'emboutissage
EP1642990A1 (en) * 2003-06-19 2006-04-05 Nippon Steel Corporation High strength steel plate excellent in formability and method for production thereof

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4716359B2 (ja) * 2005-03-30 2011-07-06 株式会社神戸製鋼所 均一伸びに優れた高強度冷延鋼板およびその製造方法
CN103695762B (zh) * 2013-12-13 2016-06-08 安徽工业大学 一种抗拉强度560～590MPa热轧轮辋用钢及其制造方法
KR102648441B1 (ko) * 2015-09-22 2024-03-15 타타 스틸 이즈무이덴 베.뷔. 우수한 신장-플랜지 성형성을 가진 열간-압연 고강도 롤-성형 가능한 강 시트 및 그 제조방법
DE102016202005A1 (de) * 2016-02-10 2017-08-10 Thyssenkrupp Ag Nutzfahrzeugrad und Verwendung
DE102016211411A1 (de) * 2016-06-24 2017-12-28 Thyssenkrupp Ag Fahrzeugrad und Verwendung

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2253841A1 (es) * 1973-12-06 1975-07-04 Centro Speriment Metallurg
US4316753A (en) * 1978-04-05 1982-02-23 Nippon Steel Corporation Method for producing low alloy hot rolled steel strip or sheet having high tensile strength, low yield ratio and excellent total elongation
BE899253A (fr) * 1984-03-27 1984-07-16 Gielen Paul M E L Un nouvel acier hsla, principalement pour l'industrie automobile.
JPH0559485A (ja) * 1991-08-27 1993-03-09 Sumitomo Metal Ind Ltd 高延性熱延高張力鋼板とその製造方法
EP0586704A1 (en) * 1991-05-30 1994-03-16 Nippon Steel Corporation High-yield-ratio hot-rolled high-strength steel sheet excellent in formability or in both of formability and spot weldability, and production thereof
JPH06264183A (ja) * 1993-03-11 1994-09-20 Sumitomo Metal Ind Ltd 高加工性熱延高張力鋼板とその製造方法
US5470529A (en) * 1994-03-08 1995-11-28 Sumitomo Metal Industries, Ltd. High tensile strength steel sheet having improved formability

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2253841A1 (es) * 1973-12-06 1975-07-04 Centro Speriment Metallurg
US4316753A (en) * 1978-04-05 1982-02-23 Nippon Steel Corporation Method for producing low alloy hot rolled steel strip or sheet having high tensile strength, low yield ratio and excellent total elongation
BE899253A (fr) * 1984-03-27 1984-07-16 Gielen Paul M E L Un nouvel acier hsla, principalement pour l'industrie automobile.
EP0586704A1 (en) * 1991-05-30 1994-03-16 Nippon Steel Corporation High-yield-ratio hot-rolled high-strength steel sheet excellent in formability or in both of formability and spot weldability, and production thereof
JPH0559485A (ja) * 1991-08-27 1993-03-09 Sumitomo Metal Ind Ltd 高延性熱延高張力鋼板とその製造方法
JPH06264183A (ja) * 1993-03-11 1994-09-20 Sumitomo Metal Ind Ltd 高加工性熱延高張力鋼板とその製造方法
US5470529A (en) * 1994-03-08 1995-11-28 Sumitomo Metal Industries, Ltd. High tensile strength steel sheet having improved formability

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 017, no. 373 (C - 1083) 14 July 1993 (1993-07-14) *
PATENT ABSTRACTS OF JAPAN vol. 018, no. 668 (C - 1289) 16 December 1994 (1994-12-16) *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2748033A1 (fr) * 1996-04-26 1997-10-31 Lorraine Laminage Procede de realisation d'une bande de tole d'acier laminee a chaud a tres haute resistance utilisable pour la mise en forme et notamment pour l'emboutissage
EP1642990A1 (en) * 2003-06-19 2006-04-05 Nippon Steel Corporation High strength steel plate excellent in formability and method for production thereof
EP1642990A4 (en) * 2003-06-19 2006-11-29 Nippon Steel Corp HIGH-RESISTANCE STEEL PLATE WITH EXCELLENT DIVISION AND MANUFACTURING METHOD THEREFOR
US7922835B2 (en) 2003-06-19 2011-04-12 Nippon Steel Corporation High strength steel sheet excellent in formability
US8262818B2 (en) 2003-06-19 2012-09-11 Nippon Steel Corporation Method for producing high strength steel sheet excellent in formability

Also Published As

Publication number Publication date
TR199701721T1 (xx) 1998-04-21
HUP9801755A3 (en) 1999-09-28
PL324556A1 (en) 1998-06-08
HUP9801755A2 (hu) 1998-11-30
MX9710229A (es) 1998-03-29
CZ402697A3 (cs) 1998-06-17
CA2224813A1 (en) 1997-01-03
AR002502A1 (es) 1998-03-25
BR9608969A (pt) 1999-06-29
CN1190998A (zh) 1998-08-19
WO1997000331A1 (de) 1997-01-03

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