WO1999050463A1 - Method for manufacturing a forming steel having good forming characteristics and low-carbon grade forming steel - Google Patents

Method for manufacturing a forming steel having good forming characteristics and low-carbon grade forming steel Download PDF

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Publication number
WO1999050463A1
WO1999050463A1 PCT/NL1999/000182 NL9900182W WO9950463A1 WO 1999050463 A1 WO1999050463 A1 WO 1999050463A1 NL 9900182 W NL9900182 W NL 9900182W WO 9950463 A1 WO9950463 A1 WO 9950463A1
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WO
WIPO (PCT)
Prior art keywords
steel
forming
rolled
annealing
temperature
Prior art date
Application number
PCT/NL1999/000182
Other languages
French (fr)
Inventor
Gerard Krusemeijer
Henk Vegter
Sybrand van der ZWAAG
Original Assignee
Corus Staal Bv
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 Corus Staal Bv filed Critical Corus Staal Bv
Priority to AU30595/99A priority Critical patent/AU3059599A/en
Publication of WO1999050463A1 publication Critical patent/WO1999050463A1/en

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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
    • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
    • C21D8/0421—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the working steps
    • C21D8/0426—Hot rolling
    • 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
    • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
    • C21D8/0447—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the heat treatment
    • C21D8/0463—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the heat treatment following hot rolling
    • 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
    • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
    • C21D8/0478—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing involving a particular surface treatment

Definitions

  • the invention relates to a method for manufacturing a forming steel having good forming characteristics.
  • Forming steel having good forming characteristics is generally obtained via the so-called cold rolling route. This involves an intermediate first obtained by hot rolling being further processed by cold rolling, followed by the process steps of annealing and temper-rolling, to achieve the desired characteristics in the end product.
  • the texture of hot-rolled material can be controlled to a lesser extent than that of cold-rolled material, because a number of production steps by which the texture can be controlled are omitted.
  • the desired forming characteristics therefore need to be obtained via different routes.
  • the invention then consists in hot-rolling starting with a steel slab having a C content of ⁇ 0.005 wt %, said slab being rolled substantially in the austenitic temperature range and the final treatment comprising an annealing treatment at a temperature of between 700° and 750°C.
  • the hot-rolled steel is, according to the invention, coiled at a temperature of between 700° and 750°C. On the coil the strip material then cools down slowly, resulting in a long annealing time.
  • the hot-rolled steel is finish-rolled at a temperature of from 550° to 600°C, followed by a continuous annealing treatment at a temperature of between 700° and 750°C.
  • the material in particular, is to be made - 2 -
  • annealing insensitive to ageing, and if good surface quality likewise has to meet certain requirements, it is preferred, according to the invention, for annealing to be carried out over a period of about 60 minutes.
  • the annealing treatment can then be the heat treatment required while the rolled strip is thermally metallically coated.
  • the best forming characteristics and the best surface quality of formed products obtained from the forming steel obtained are achieved if the forming steel is free from free interstitials. This result can be achieved by adding to the steel one or more of the elements Ti, Nb or B.
  • the invention also relates to a low-C grade forming steel having a C content of ⁇ 0.005% in the form of strip or plate having a structure such as that obtained by a cast steel slab being hot-rolled substantially in the austenitic range, the final treatment comprising an annealing treatment at a temperature of between 700° and 750°C.
  • a forming steel where the steel is furthermore of a Ti, Nb or B-Sulc grade.
  • said forming steel is additionally provided with a thermal metallic layer such as a thermal zinc layer.

Abstract

Method for manufacturing a forming steel having good forming characteristics, wherein a steel slab having a C content of ∫0.005 % is hot-rolled substantially in the austenitic temperature range and wherein the final treatment comprises an annealing treatment at a temperature of between 700° and 750 °C. The annealing treatment can be the heat treatment employed while the rolled strip is thermally metallically coated.

Description

METHOD FOR MANUFACTURING A FORMING STEEL HAVING GOOD FORMING CHARACTERISTICS AND LOW-CARBON GRADE FORMING STEEL
The invention relates to a method for manufacturing a forming steel having good forming characteristics.
Forming steel having good forming characteristics is generally obtained via the so-called cold rolling route. This involves an intermediate first obtained by hot rolling being further processed by cold rolling, followed by the process steps of annealing and temper-rolling, to achieve the desired characteristics in the end product.
The ultimate options for forming such a steel product arrived at are largely determined by the chemical composition, the texture, the grain size and the amount of free interstitials (mainly of C and N).
The known way of manufacturing forming steel requires many processing steps, including uncoiling and coiling operations, as a result of which the manufacturing costs of said forming steel are considerably increased.
Underlying the invention is the search for a method with which a number of these processing steps could be avoided.
Should, in particular, a method for manufacturing a hot-rolled product having good forming characteristics be achievable, this would lead to a significantly shorter production route, shorter delivery time and lower cost price.
The texture of hot-rolled material can be controlled to a lesser extent than that of cold-rolled material, because a number of production steps by which the texture can be controlled are omitted. The desired forming characteristics therefore need to be obtained via different routes.
The invention then consists in hot-rolling starting with a steel slab having a C content of < 0.005 wt %, said slab being rolled substantially in the austenitic temperature range and the final treatment comprising an annealing treatment at a temperature of between 700° and 750°C. In one embodiment of the novel method, the hot-rolled steel is, according to the invention, coiled at a temperature of between 700° and 750°C. On the coil the strip material then cools down slowly, resulting in a long annealing time.
According to another embodiment of the novel method, the hot-rolled steel is finish-rolled at a temperature of from 550° to 600°C, followed by a continuous annealing treatment at a temperature of between 700° and 750°C.
Depending on the annealing method followed, it is possible to vary the characteristics of the forming steel. If the material, in particular, is to be made - 2 -
insensitive to ageing, and if good surface quality likewise has to meet certain requirements, it is preferred, according to the invention, for annealing to be carried out over a period of about 60 minutes.
If good mechanical characteristics are aimed for it is found that preference can be given to an annealing time of < 100 sec. In the latter case it proved desirable, according to the invention, for the rolled strip to be brought to the annealing temperature within 100 sec and for it to be cooled, after annealing, to 600°C within 150 sec.
An additional saving can be achieved if the end product is to be given a metallic coating layer, for example a zinc layer. According to the invention, the annealing treatment can then be the heat treatment required while the rolled strip is thermally metallically coated.
Obviously it is possible for the casting of the slab, the rolling thereof and/or the annealing treatment to be carried out in separate treatments. The greatest cost price benefits are obtained, however, by these treatments, according to the invention, being carried out in one continuous treatment. Such a method is described, for example, in
WO97/46332.
The best forming characteristics and the best surface quality of formed products obtained from the forming steel obtained are achieved if the forming steel is free from free interstitials. This result can be achieved by adding to the steel one or more of the elements Ti, Nb or B.
Preference is given to a method which uses as a starting material a steel which also contains between 0.03 and 0.1 wt % of Ti, preferably between 0.04 and 0.07 wt % ofTi.
The invention also relates to a low-C grade forming steel having a C content of < 0.005% in the form of strip or plate having a structure such as that obtained by a cast steel slab being hot-rolled substantially in the austenitic range, the final treatment comprising an annealing treatment at a temperature of between 700° and 750°C. Preference is further given to a forming steel where the steel is furthermore of a Ti, Nb or B-Sulc grade. In the case of a special embodiment of the forming steel according to the invention, said forming steel is additionally provided with a thermal metallic layer such as a thermal zinc layer.
The priority application on which the present application is based comprehensively describes some of the terminology, the tests of test materials and the results of those tests. Said priority application is incorporated by reference into the present application.

Claims

1. Method for manufacturing a forming steel having good forming characteristics, wherein a steel slab having a C content of < 0.005% is hot-rolled substantially in the austenitic temperature range and wherein the final treatment comprises an annealing treatment at a temperature of between 700┬░ and 750┬░C.
2. Method according to Claim 1, characterized in that the hot-rolled steel is coiled at a temperature of from 700┬░ to 750┬░C.
3. Method according to Claim 1, characterized in that the hot-rolled steel is finish rolled at a temperature of from 550┬░C to 600┬░C, followed by a continuous annealing treatment at a temperature of between 700┬░ and 750┬░C.
4. Method according to any one of Claims 1-2, characterized in that annealing takes place over a period of about 60 minutes.
5. Method according to Claim 3, characterized in that annealing is carried out over a period of < 100 sec.
6. Method according to Claim 5, characterized in that the rolled strip is brought to the annealing temperature within 100 sec and after annealing is cooled to 600┬░C within 150 sec.
7. Method according to Claim 5 or 6, characterized in that the anneal is a heat treatment while the rolled strip is thermally metallically coated.
8. Method according to Claim 7, characterized in that the strip is provided with a zinc layer.
9. Method according to any one of Claims 1-8, characterized in that the casting of the slab, the rolling thereof and the annealing treatment are carried out in one continuous treatment.
10. Method according to any one of the preceding claims, characterized in that the starting material used is a steel which additionally contains between 0.03% and
0.1% and preferably between 0.04% and 0.07% of Ti. - 4 -
11. Low-C grade forming steel having a C content < 0.005%, in the form of strip or plate, having a structure such as obtained by a cast steel slab being hot-rolled in substantially the austenitic range, the final treatment comprising an annealing treatment at a temperature of between 700┬░ and 750┬░C.
12. Forming steel according to Claim 11, characterized in that the steel is furthermore of a Ti, Nb or B-Sulc grade.
13. Forming steel according to Claim 11 or 12, characterized in that it is provided with a thermal metallic coating layer.
14. Forming steel according to Claim 13, characterized in that the metallic coating layer is a zinc layer.
PCT/NL1999/000182 1998-03-27 1999-03-29 Method for manufacturing a forming steel having good forming characteristics and low-carbon grade forming steel WO1999050463A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU30595/99A AU3059599A (en) 1998-03-27 1999-03-29 Method for manufacturing a forming steel having good forming characteristics andlow-carbon grade forming steel

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL1008728 1998-03-27
NL1008728 1998-03-27

Publications (1)

Publication Number Publication Date
WO1999050463A1 true WO1999050463A1 (en) 1999-10-07

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/NL1999/000182 WO1999050463A1 (en) 1998-03-27 1999-03-29 Method for manufacturing a forming steel having good forming characteristics and low-carbon grade forming steel

Country Status (2)

Country Link
AU (1) AU3059599A (en)
WO (1) WO1999050463A1 (en)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0376733A1 (en) * 1988-12-28 1990-07-04 Kawasaki Steel Corporation Method of manufacturing steel sheet having excellent deep-drawability
JPH06122923A (en) * 1992-10-12 1994-05-06 Kobe Steel Ltd Production of high ductility hot rolled steel sheet excellent in longitudinal cracking resistance
DE19600990A1 (en) * 1996-01-14 1997-07-17 Thyssen Stahl Ag Process for hot rolling steel strips
WO1997046332A1 (en) * 1996-06-07 1997-12-11 Hoogovens Staal B.V. Method and apparatus for the manufacture of a steel strip
EP0823294A1 (en) * 1996-08-05 1998-02-11 MANNESMANN Aktiengesellschaft Method and installation for manufacturing strips of low-carbon and ultra-low-carbon steel

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0376733A1 (en) * 1988-12-28 1990-07-04 Kawasaki Steel Corporation Method of manufacturing steel sheet having excellent deep-drawability
JPH06122923A (en) * 1992-10-12 1994-05-06 Kobe Steel Ltd Production of high ductility hot rolled steel sheet excellent in longitudinal cracking resistance
DE19600990A1 (en) * 1996-01-14 1997-07-17 Thyssen Stahl Ag Process for hot rolling steel strips
WO1997046332A1 (en) * 1996-06-07 1997-12-11 Hoogovens Staal B.V. Method and apparatus for the manufacture of a steel strip
EP0823294A1 (en) * 1996-08-05 1998-02-11 MANNESMANN Aktiengesellschaft Method and installation for manufacturing strips of low-carbon and ultra-low-carbon steel

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
MESSIEN P: "LAMINAGE FERRITIQUE DE BANDES A CHAUD MINCES EN ACIER DOUX *", CAHIERS D'INFORMATIONS TECHNIQUES DE LA REVUE DE METALLURGIE, vol. 88, no. 5, 1 May 1991 (1991-05-01), pages 433 - 442, XP000249515, ISSN: 0035-1563 *
PATENT ABSTRACTS OF JAPAN vol. 018, no. 415 (C - 1233) 4 August 1994 (1994-08-04) *

Also Published As

Publication number Publication date
AU3059599A (en) 1999-10-18

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