EP2155916A1 - Low density steel with good stamping capability - Google Patents

Low density steel with good stamping capability

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Publication number
EP2155916A1
EP2155916A1 EP08805524A EP08805524A EP2155916A1 EP 2155916 A1 EP2155916 A1 EP 2155916A1 EP 08805524 A EP08805524 A EP 08805524A EP 08805524 A EP08805524 A EP 08805524A EP 2155916 A1 EP2155916 A1 EP 2155916A1
Authority
EP
European Patent Office
Prior art keywords
sheet
rolled
steel
cold
temperature
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.)
Granted
Application number
EP08805524A
Other languages
German (de)
French (fr)
Other versions
EP2155916B1 (en
EP2155916B2 (en
Inventor
Astrid Perlade
Xavier Garat
Jean-Louis Uriarte
Olivier Bouaziz
Josée Drillet
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.)
ArcelorMittal France SA
Original Assignee
ArcelorMittal France SA
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Filing date
Publication date
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Application filed by ArcelorMittal France SA filed Critical ArcelorMittal France SA
Priority to EP08805524.9A priority Critical patent/EP2155916B2/en
Priority to PL08805524T priority patent/PL2155916T5/en
Publication of EP2155916A1 publication Critical patent/EP2155916A1/en
Publication of EP2155916B1 publication Critical patent/EP2155916B1/en
Application granted granted Critical
Publication of EP2155916B2 publication Critical patent/EP2155916B2/en
Active 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
    • 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
    • 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
    • C21D8/021—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips involving a particular fabrication or treatment of ingot or slab
    • 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
    • C21D8/021—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips involving a particular fabrication or treatment of ingot or slab
    • C21D8/0215—Rapid solidification; Thin strip casting
    • 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
    • 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
    • C21D8/0236—Cold 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
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • 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
    • C21D8/041—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 fabrication or treatment of ingot or slab
    • 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
    • C21D8/041—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 fabrication or treatment of ingot or slab
    • C21D8/0415—Rapid solidification; Thin strip casting
    • 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
    • C21D8/0421—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
    • C21D8/0436—Cold 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
    • C22C38/002—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
    • C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
    • 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
    • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn

Definitions

  • the invention relates to a ferritic sheet of hot-rolled or cold-rolled steel, having a strength greater than 400 MPa and a density of less than about 7.3, and its manufacturing process.
  • the reduction in the amount of CO 2 emitted by motor vehicles includes the reduction of motor vehicles. This relief can be achieved:
  • the first channel is the subject of much research, steels whose mechanical strength ranges from 800 MPa to more than 1000 MPa have been proposed by the steel industry. The density of these steels however remains close to 7.8, which is the density of conventional steels.
  • Patent EP1485511 thus discloses steels comprising additions of silicon (2-10%) and aluminum (1-10%) of ferritic microstructure and also containing carburized phases.
  • silicon 2-10%)
  • aluminum 1-10%)
  • carburized phases the relatively high silicon content of these steels may in some cases pose problems of coating and ductility.
  • Steels containing an addition of approximately 8% of aluminum are also known: however, difficulties can be encountered during the manufacture of these steels, in particular during cold rolling. There may also be problems of scouring during the stamping of these steels. When these contain more than 0.010% C 1 a precipitation of carburized phases can increase the fragility. The use of such steels for the manufacture of structural parts is then impossible.
  • the object of the invention is to propose hot-rolled or cold-rolled steel sheets having simultaneously:
  • the object of the invention is also to provide a manufacturing method compatible with the usual industrial installations.
  • the subject of the invention is a ferritic hot-rolled steel sheet whose composition comprises, the contents being expressed by weight: 0.001 ⁇ C ⁇ 0.15%, Mn ⁇ 1%, Si ⁇ 1.5% , 6% ⁇ AI ⁇ 10%, 0.020% ⁇ Ti ⁇ 0.5%, S ⁇ 0.050%, P ⁇ 0, 1% and, optionally, one or more elements selected from: Cr ⁇ 1%, Mo ⁇ 1%, Ni ⁇ 1%, Nb ⁇ 0.1%, V ⁇ 0.2%, B ⁇ 0.01%, the rest of the composition consisting of iron and unavoidable impurities resulting from the preparation, the average size
  • the invention also relates to a ferritic cold-rolled and annealed sheet made of steel of the above composition, characterized in that said ferrite grain div measured on a surface perpendicular to the direction transverse to the rolling is less than 100 microns. its structure consists
  • the composition comprises: 0.001% ⁇ C ⁇ 0.010%, Mn ⁇ 0.2%.
  • the composition comprises: 0.010% ⁇ C ⁇ 0.15%, 0.2% ⁇ Mn ⁇ 1%.
  • the composition comprises: 7.5% ⁇ Al ⁇ 10%.
  • the composition comprises: 7.5% ⁇ Al ⁇ 8.5%.
  • the carbon content in solid solution is preferably less than 0.005% by weight.
  • the strength of the sheet is greater than or equal to 400 MPa.
  • the strength of the sheet is greater than or equal to 600 MPa.
  • the subject of the invention is also a process for manufacturing a hot-rolled steel sheet according to which a steel of composition is supplied according to one of the above compositions, the steel is cast in the form of a semi-finished product. which is heated to a temperature greater than or equal to 1150 ° C.
  • the semi-finished product is hot-rolled to obtain a sheet, by means of at least two rolling stages carried out at temperatures above 1050 ° C., the reduction ratio each step being greater than or equal to 30%, the time elapsing between each of the rolling steps, and the next rolling step being greater than or equal to 10 s.
  • the rolling is completed at a temperature T F ⁇ _ greater than or equal to 900 ° C., the sheet is cooled so that the time interval t p flowing between 850 and 700 ° C. is greater than 3 s, in order to obtain a precipitation of precipitates K, then coil the sheet at a temperature T b o b between 500 and 700 0 C.
  • the casting is carried out directly in the form of thin slabs or thin strips between contra-rotating rolls.
  • the invention also relates to a method of manufacturing a cold-rolled and annealed steel sheet according to which a hot-rolled steel sheet manufactured according to one of the above modes is supplied, then the sheet is cold-rolled. with a reduction ratio of between 30 and 90%, so as to obtain a cold-rolled sheet.
  • the cold-rolled sheet is then heated to a temperature T 'with a speed V 0 greater than 3 ° C./s, then the sheet is cooled to a speed VR less than 100 ° C./s, the temperature T' and the speed V R being selected so as to obtain complete recrystallization, a linear fraction f of intergranular precipitates K of less than 30% and a carbon content in solid solution of less than 0.005% by weight.
  • the cold-rolled sheet is preferably heated to a temperature T 'of between 750 and 950 ° C.
  • a sheet of composition is supplied: 0.010% ⁇ C ⁇ 0.15%, 0.2% ⁇ Mn ⁇ 1%, Si ⁇ 1.5%, 6% ⁇ AI ⁇ 10%, 0.020% ⁇ Ti ⁇ 0.5%, S ⁇ 0.050%, P ⁇ 0.1% and, optionally, one or more elements selected from: Cr ⁇ 1%, Mo ⁇ 1 %, Ni ⁇ 1%, Nb ⁇ 0.1%, V ⁇ 0.2%, B ⁇ 0.01%, the remainder of the composition consisting of iron and unavoidable impurities resulting from the preparation, and heating the cold-rolled sheet at a temperature T chosen so as to avoid the dissolution of precipitates K.
  • the invention also relates to the use of steel sheets according to one of the above modes or manufactured in one of the above modes for the manufacture of skin parts or structural parts in the automotive field.
  • FIG. 1 schematically defines the linear fraction f of ferritic grain boundaries with intergranular precipitation
  • FIG. 2 shows the microstructure of a hot-rolled steel sheet according to the invention.
  • FIG. 3 shows the microstructure of a hot-rolled steel sheet manufactured according to conditions that do not satisfy the invention
  • FIG. 4 and 5 illustrate the microstructure of two cold-rolled sheets and annealed according to the invention.
  • FIG. 6 shows the microstructure of a cold-rolled and annealed steel sheet manufactured according to conditions that do not satisfy the invention
  • the present invention relates to steels having a reduced density, less than about 7.3, while retaining satisfactory use characteristics.
  • the invention relates in particular to a manufacturing method for controlling the precipitation of intermetallic carbides, the microstructure, and the texture in steels including particular combinations of carbon, aluminum and titanium.
  • carbon plays an important role in the formation of the microstructure and in the mechanical properties:
  • the carbon content is between 0.001% and 0.15%: below 0.001%, significant curing can not be obtained.
  • the carbon content is greater than 0.15%, the cold rollability of the steels is low.
  • the steels according to the invention have a ferritic microstructure at ambient temperature. Different particular embodiments of the invention may be implemented, depending on the carbon and manganese content of the steel:
  • the minimum resistance R m obtained is 400MPa.
  • the minimum resistance obtained is 600 MPa .
  • the inventors have demonstrated that this element contributes to a significant hardening by a precipitation of carbides (TiC or kappa precipitates) and a refinement of the ferritic grain.
  • the addition of carbon only leads to a small loss of ductility if the precipitation of carbides is not intergranular or if the carbon is not in solid solution.
  • the steel has a ferritic matrix at any temperature during the manufacturing cycle, that is to say from the solidification from the casting.
  • silicon is an element that reduces the density of steel.
  • an excessive addition of silicon beyond 1, 5%, causes the formation of strongly adherent oxides and the possible appearance of surface defects, leading in particular to a lack of wettability in dip galvanizing operations.
  • this excessive addition decreases ductility.
  • Aluminum is an important element of the invention: when its content is less than 6% by weight, a sufficient reduction of the density can not be obtained. When its content is greater than 10%, there is a risk of formation of embrittling intermetallic phases F ⁇ 3 AI and FeAI.
  • the aluminum content is between 7.5 and 10%: within this range, the density of the sheet is less than about 7.1.
  • the aluminum content is between 7.5 and 8.5%: in this range, satisfactory lightening is obtained without reducing the ductility.
  • the steel also contains a minimum titanium content of 0.020% which contributes to limiting the carbon content in solid solution in an amount of less than 0.005% by weight, thanks to a precipitation of TiC.
  • Carbon in solid solution has a deleterious effect on ductility because it reduces the mobility of dislocations. Beyond 0.5% titanium, the precipitation of titanium carbides occurs in too large a quantity, and the ductility is reduced.
  • the sulfur content is less than 0.050% so as to limit a possible precipitation of TiS which would reduce the ductility.
  • the phosphorus content is also limited to 0.1%.
  • steel may also contain, alone or in combination:
  • chromium, molybdenum, or nickel in an amount of less than or equal to 1%. These elements provide additional hardening by solid solution.
  • Micro-alloy elements such as niobium and vanadium in an amount of less than 0.1 and 0.2% by weight respectively, can be added to obtain a complementary hardening by precipitation.
  • the rest of the composition consists of iron and unavoidable impurities that result from the elaboration.
  • the structure of the steels according to the invention comprises a homogeneous distribution of highly disoriented ferritic grains: the strong disorientation between neighboring grains makes it possible to avoid the crimping defect: this defect is characterized, during the cold forming of sheets, by the localized and premature appearance of strips in the direction of rolling, forming a relief. This phenomenon is due to the presence of recrystallized and weakly disoriented grain groups, since they originate from the same original grain before recrystallization.
  • a scuff sensitive structure is characterized by spatial texture distribution. When the scuffing phenomenon is present, the cross-machine mechanical properties (especially the uniform elongation) and the formability are greatly reduced.
  • the microstructure at ambient temperature of the steels consists of an equiaxed ferrite matrix whose average grain size is less than 50 micrometers.
  • Aluminum is mainly in solid solution in this matrix based on iron.
  • These steels contain kappa precipitates ("K") which are a ternary Fe 3 AIC x intermetallic phase. The presence of these precipitates in the ferritic matrix leads to a significant hardening.
  • ⁇ di denotes the total length of the grain boundaries
  • the ferritic grain is not equiaxed but its average size d
  • V denotes the grain size measured by the method of linear intercepts on a representative surface (S) perpendicular to the direction transverse to the rolling. The measure of div is made in the direction perpendicular to the thickness of the sheet.
  • S representative surface
  • This non-equiaxial grain morphology, having an elongation in the direction of rolling, may for example be present on hot-rolled steel sheets according to the invention.
  • the implementation of the method for manufacturing a hot-rolled sheet according to the invention is as follows:
  • This casting may be carried out in ingots, or continuously in the form of slabs of thickness of the order of 200 mm.
  • the casting can also be carried out in the form of thin slabs of a few tens of millimeters thick, or thin strips, between contra-rotating steel rolls.
  • This method of manufacture in the form of thin products is particularly advantageous because it makes it easier to obtain a fine structure which favors the production of the invention as will be seen later.
  • the skilled person will determine the casting conditions satisfying both the need to obtain a fine and equiaxed structure after casting, and that of meeting the usual requirements of an industrial casting.
  • the cast semi-finished products are first brought to a temperature above 1150 ° C. in order to reach at all points a temperature favorable to the high deformations which the steel will undergo during the various rolling steps.
  • the hot rolling step of these semi-products starting at more than 1150 ° C. can be done directly after casting so well. that an intermediate heating step is not necessary in this case.
  • the semi-finished product is hot rolled to obtain a sheet, by a succession of rolling steps.
  • Each of the steps corresponds to a reduction in the thickness of the product by passing through rolling mill rolls. Under industrial conditions, these steps are performed when roughing the semi-finished product on a band train.
  • the reduction rate associated with each of these stages is defined by: (thickness of the half-product after rolling step-thickness before rolling) /
  • the rolling is completed at a TFL temperature greater than or equal to 900 0 C, so as to obtain a complete recrystallization.
  • the sheet obtained is then cooled: the inventors have demonstrated that a particularly effective precipitation of precipitates K and TiC carbides was obtained when the time interval t p flowing on cooling between 850 and 700 ° C. was greater than 3 sec. In this way, an intense precipitation is obtained which is favorable to hardening.
  • the sheet is then reeled at a temperature T bOb between 500 and 700 0 C. This step completes the precipitation of TiC.
  • a hot-rolled sheet is obtained, the thickness of which is, for example, from 2 to 6 mm. If it is desired to manufacture a sheet of lower thickness, for example from 0.6 to 1.5 mm, the manufacturing process is as follows:
  • a hot-rolled sheet is supplied, manufactured according to the method described above. Naturally, if the surface state of the sheet requires it, stripping will be carried out by means of a method known per se.
  • the cold-rolled sheet is then heated with a heating rate V 0 greater than 3 ° C./s, in order to avoid a restoration which would reduce the capacity for subsequent recrystallization.
  • Reheating is performed up to an annealing temperature T 'which will be chosen so as to obtain a complete recrystallization of the initial structure hardened.
  • the sheet is then cooled at a speed V R of less than 100 ° C./s so as not to cause any embrittlement by excess of carbon in solid solution. This result is particularly surprising in that it could be thought that a rapid cooling rate would be favorable to reduce embrittling precipitation.
  • a solid solution carbon content of less than 0.005% Preferably be chosen a temperature T 'between 750 and 95o 0 C to achieve complete recrystallization.
  • Example 1 Hot rolled sheets Steels were produced by casting in the form of half-products with a thickness of about 50 mm. Their compositions, expressed in weight percent, are shown in Table 1 below.
  • the half-products were heated to a temperature of 122O 0 C and hot rolled to obtain a sheet of a thickness of about 3.5 mm. From the same composition, some steels have been subjected to different hot rolling conditions.
  • the references 11-a, 11-b, 11-c, 11-d, 11-e designate for example five steel sheets manufactured under different conditions from the composition 11.
  • the table 2 details the conditions of the successive stages of hot rolling:
  • Table 3 shows the density measured on the plates of Table 2 and certain mechanical and microstructural characteristics.
  • the resistance Rm the uniform elongation A u , the elongation at break A t, have thus been measured in the cross-machine direction with respect to rolling.
  • the grain size div was also measured by the linear intercepts method according to the NF EN ISO 643 standard on a surface perpendicular to the direction transverse to the rolling. The measure of div was made in the direction perpendicular to the thickness of the sheet. In order to obtain increased mechanical properties, a grain size div less than 100 microns is particularly desired.
  • the steel sheets according to the invention are characterized by a grain size d IV less than 100 microns and have a mechanical strength ranging from 505-645 MPa .
  • the sheets 11b and 11e were laminated with a time interpasse too short. Their structure is then coarse and not recrystallized or insufficiently recrystallized as shown in Figure 3 relating to the sheet 11e. As a result, the ductility is decreased and the sheet is more sensitive to the lack of creasing. Similar conclusions can be drawn for sheet 13b.
  • the sheet 11c was rolled with an insufficient number of rolling steps with a rate greater than 30%, a time interpasse and a time interval t p too short.
  • the consequences are identical to those noted on plates 11b and 11e. Since the time interval t p is too low, a hardening precipitation of K precipitates and TiC carbides occurs only partially, which makes it impossible to take full advantage of the curing possibilities.
  • the steel R1 has an insufficient titanium content which leads to a solid solution carbon content that is too high: the folding ability is then reduced.
  • Steel R2 has an insufficient aluminum content which does not allow to obtain a density lower than 7.3.
  • R3, R4, R5 and R6 steels contain too much aluminum and possibly carbon: their ductility is reduced due to the excessive precipitation of intermetallic phases or carbides
  • Example 2 Cold-rolled and annealed sheets
  • Table 6 shows some of the mechanical, chemical, microstructural and density characteristics of the sheets of Table 5.
  • the yield strength Re 1 the resistance Rm, the resistance, was measured by transverse tensile tests with respect to rolling. uniform elongation A u , elongation at break At. By means of observations by scanning electron microscopy, it was noted the possible presence of cleavage facets on the rupture surfaces of test specimens.
  • the carbon content C SO ⁇ in solid solution was also measured.
  • microstructure of these recrystallized sheets consists of equiaxed ferrite whose average ⁇ - grain size was measured in the transverse rolling direction.
  • Table 6 Mechanical properties of cold-rolled and annealed sheets obtained from steels 11 and 13.
  • the sheets of Mal and I3a1 steels have a solid solution carbon content, a ferritic equiaxed grain size, and a grain boundary coverage rate that satisfies the requirements of the invention. As a result, the ability to bend, stamping, scratch resistance of these sheets, is high.
  • FIG. 4 illustrates the microstructure of the steel sheet Mal according to the invention.
  • FIG. 5 illustrates the microstructure of another steel sheet according to the invention.
  • I3a1 Note the presence of K precipitates of which only a small amount is present in intergranular form, which allows to maintain a high ductility.
  • FIG. 6 illustrates the microstructure of the sheet I3a3: this was annealed at too high a temperature T ': the precipitates K present before the annealing were dissolved, their subsequent precipitation after cooling intervened in an intergranular form in excessive amounts . This results in the local presence of fragile beaches on the fracture facies.
  • the I3a4 sheet was also annealed at a temperature which causes partial dissolution of the precipitates K.
  • the carbon content in solid solution is excessive.
  • the steel sheet I1c1 was made from a hot-rolled sheet not satisfying the requirements of the invention: the equiaxial grain size is too large, the crimping resistance and the stamping ability are insufficient.
  • the hot-rolled sheet 13b which does not satisfy the criteria of the invention, is not suitable for deformation since transverse cracks appear during cold rolling.
  • the steels according to the invention thus have a combination of properties (density, mechanical strength, deformability, weldability, coating) particularly interesting. These steel sheets are used with advantage for the manufacture of skin parts or structure in the automotive field.

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Abstract

The invention relates to a hot-rolled ferritic sheet made of steel having the following composition in weight: 0.001< C ≤0.15%, Mn ≤ 1 %, Si < 1.5%, 6% ≤AI < 10%, 0.020% < Ti < 0.5%, S < 0.050%, P < 0.1 %, and optionally one or more elements selected from: Cr < 1 %, Mo < 1 %, Ni < 1%, Nb < 0.1 %, V ≤ 0.2%,, B ≤ 0.010%, the balance of the composition consisting of Fe and unavoidable impurities resulting from the manufacture, the average grain size of ferrite dIV as measured on a surface perpendicular to the transverse relative to the rolling being lower than 100 micrometers.

Description

ACIER A FAIBLE DENSITE PRESENTANT UNE BONNE APTITUDE A LOW DENSITY STEEL HAVING GOOD ABILITY
L'EMBOUTISSAGESTAMPING
L'invention concerne une tôle ferritique d'acier laminée à chaud ou à froid, possédant une résistance supérieure à 400 MPa et une densité inférieure à 7,3 environ, ainsi que son procédé de fabrication.The invention relates to a ferritic sheet of hot-rolled or cold-rolled steel, having a strength greater than 400 MPa and a density of less than about 7.3, and its manufacturing process.
La diminution de la quantité de CO2 émis par les véhicules automobiles passe notamment par l'allégement des véhicules automobiles. Cet allégement peut être réalisé :The reduction in the amount of CO 2 emitted by motor vehicles includes the reduction of motor vehicles. This relief can be achieved:
- grâce à une augmentation des caractéristiques mécaniques des aciers constituant les pièces structurales ou les pièces de peau, outhanks to an increase in the mechanical characteristics of the steels constituting the structural parts or the pieces of skin, or
- à caractéristiques mécaniques données, grâce à une réduction de la densité des aciers. - La première voie fait l'objet de nombreuses recherches, des aciers dont la résistance mécanique va de 800MPa à plus de 1000MPa ont été proposés par l'industrie sidérurgique. La densité de ces aciers reste cependant voisine de 7,8, qui est la densité d'aciers conventionnels.- with given mechanical characteristics, thanks to a reduction of the density of the steels. - The first channel is the subject of much research, steels whose mechanical strength ranges from 800 MPa to more than 1000 MPa have been proposed by the steel industry. The density of these steels however remains close to 7.8, which is the density of conventional steels.
Une seconde voie passe par l'addition d'éléments susceptibles de réduire la densité des aciers : Le brevet EP1485511 divulgue ainsi des aciers comportant des additions de silicium (2-10%) et d'aluminium (1-10%) de microstructure ferritique, et contenant également des phases carburées. Cependant, la teneur en silicium relativement élevée de ces aciers peut poser dans certains cas des problèmes de revêtabilité et de ductilité. On connaît par ailleurs des aciers contenant une addition d'environ 8% d'aluminium : on peut cependant rencontrer des difficultés lors de la fabrication de ces aciers, en particulier lors du laminage à froid. On peut également rencontrer des problèmes de chiffonnage lors de l'emboutissage de ces aciers. Lorsque ceux-ci contiennent plus de 0,010% C1 une précipitation de phases carburées peut augmenter la fragilité. L'utilisation de tels aciers pour la fabrication de pièces structurales est alors impossible. Le but de l'invention est de proposer des tôles d'acier laminées à chaud ou à froid présentant simultanément :A second route involves the addition of elements capable of reducing the density of the steels: Patent EP1485511 thus discloses steels comprising additions of silicon (2-10%) and aluminum (1-10%) of ferritic microstructure and also containing carburized phases. However, the relatively high silicon content of these steels may in some cases pose problems of coating and ductility. Steels containing an addition of approximately 8% of aluminum are also known: however, difficulties can be encountered during the manufacture of these steels, in particular during cold rolling. There may also be problems of scouring during the stamping of these steels. When these contain more than 0.010% C 1 a precipitation of carburized phases can increase the fragility. The use of such steels for the manufacture of structural parts is then impossible. The object of the invention is to propose hot-rolled or cold-rolled steel sheets having simultaneously:
- une densité inférieure à 7,3 environ- a density of less than about 7.3
- une résistance Rm supérieure à 400MPa - une bonne aptitude à la déformation, en particulier au laminage et une excellente résistance au chiffonnage,a resistance R m greater than 400 MPa, a good deformation capacity, in particular rolling ability and excellent resistance to creasing,
- une bonne soudabilité et une bonne revêtabilité- good weldability and good coating
Le but de l'invention est également de proposer un procédé de fabrication compatible avec les installations industrielles usuelles. A cet effet, l'invention a pour objet une tôle ferritique laminée à chaud en acier dont la composition comprend, les teneurs étant exprimées en poids : 0,001 ≤ C <0,15%, Mn < 1%, Si < 1 ,5%, 6% ≤AI < 10%, 0,020% < Ti < 0,5%, S ≤ 0,050%, P ≤ 0, 1% et, à titre optionnel, un ou plusieurs éléments choisis parmi : Cr ≤ 1%, Mo < 1 %, Ni < 1%, Nb < 0.1%, V < 0,2%, B ≤ 0,01%, le reste de la composition étant constitué de fer et d'impuretés inévitables résultant de l'élaboration, la taille moyenne de grain de ferrite div mesurée sur une surface perpendiculaire à la direction transverse par rapport au laminage étant inférieure à 100 micromètres L'invention a également pour objet une tôle ferritique laminée à froid et recuite en acier de composition ci-dessus, caractérisée en ce que sa structure est constituée de ferrite équiaxe dont la taille moyenne de grain dα est inférieure à 50 micromètres, et en ce que la fraction linéaire f de précipités K intergranulaires est inférieure à 30%, la fraction linéaire f étant définie par :The object of the invention is also to provide a manufacturing method compatible with the usual industrial installations. For this purpose, the subject of the invention is a ferritic hot-rolled steel sheet whose composition comprises, the contents being expressed by weight: 0.001 ≤ C <0.15%, Mn <1%, Si <1.5% , 6% ≤AI <10%, 0.020% <Ti <0.5%, S ≤ 0.050%, P ≤ 0, 1% and, optionally, one or more elements selected from: Cr ≤ 1%, Mo < 1%, Ni <1%, Nb <0.1%, V <0.2%, B ≤ 0.01%, the rest of the composition consisting of iron and unavoidable impurities resulting from the preparation, the average size The invention also relates to a ferritic cold-rolled and annealed sheet made of steel of the above composition, characterized in that said ferrite grain div measured on a surface perpendicular to the direction transverse to the rolling is less than 100 microns. its structure consists of equiaxed ferrite whose average grain size α is less than 50 micrometers, and in that the linear fraction f of precipitates K in is less than 30%, the linear fraction f being defined by:
f = , Ydi désignant la longueur totale des joints de grains comportant des précipités K relativement à une surface (S) considérée, ∑Li désignant laf =, Ydi denoting the total length of the grain boundaries comprising precipitates K relative to a surface (S) considered, ΣLi designating the
(S) longueur totale des joints de grains relativement à la surface (S) considérée Selon un mode particulier, la composition comprend : 0,001 % ≤C ≤ 0,010%, Mn ≤ 0,2%.(S) total length of the grain boundaries relative to the surface (S) considered According to a particular embodiment, the composition comprises: 0.001% ≤C ≤ 0.010%, Mn ≤ 0.2%.
Selon un mode préféré, la composition comprend : 0,010 % < C ≤ 0,15%, 0,2% < Mn < 1%. Préférentiellement, la composition comprend :7,5 % ≤AI ≤ 10%. Très préférentiellement, la composition comprend : 7,5 % ≤AI < 8,5%. La teneur en carbone en solution solide est préférentiellement inférieure à 0,005% en poids. Selon un mode préféré, la résistance de la tôle est supérieure ou égale à 400MPa.In a preferred embodiment, the composition comprises: 0.010% <C ≤ 0.15%, 0.2% <Mn <1%. Preferably, the composition comprises: 7.5% ≤Al ≤ 10%. Very preferably, the composition comprises: 7.5% ≤Al <8.5%. The carbon content in solid solution is preferably less than 0.005% by weight. In a preferred embodiment, the strength of the sheet is greater than or equal to 400 MPa.
A titre préférentiel, la résistance de la tôle est supérieure ou égale à 600MPa. L'invention a également pour objet un procédé de fabrication d'une tôle d'acier laminée à chaud selon lequel on approvisionne un acier de composition selon l'une des compositions ci-dessus, on coule l'acier sous forme de demi-produit qu'on porte à une température supérieure ou égale à 11500C. On lamine à chaud le demi-produit pour obtenir une tôle, grâce à au moins deux étapes de laminage effectuées à des températures supérieures à 10500C, le taux de réduction de chacune des étapes étant supérieur ou égal à 30%, le temps s'écoulant entre chacune des étapes de laminage, et l'étape de laminage suivante, étant supérieur ou égal à 10 s. On achève le laminage à une température TFι_ supérieure ou égale à 9000C, on refroidit la tôle de telle sorte que l'intervalle de temps tp s'écoulant entre 850 et 700°C soit supérieur à 3 s, pour obtenir une précipitation de précipités K, puis on bobine la tôle à une température Tbob comprise entre 500 et 7000C.As a preference, the strength of the sheet is greater than or equal to 600 MPa. The subject of the invention is also a process for manufacturing a hot-rolled steel sheet according to which a steel of composition is supplied according to one of the above compositions, the steel is cast in the form of a semi-finished product. which is heated to a temperature greater than or equal to 1150 ° C. The semi-finished product is hot-rolled to obtain a sheet, by means of at least two rolling stages carried out at temperatures above 1050 ° C., the reduction ratio each step being greater than or equal to 30%, the time elapsing between each of the rolling steps, and the next rolling step being greater than or equal to 10 s. The rolling is completed at a temperature T F ι_ greater than or equal to 900 ° C., the sheet is cooled so that the time interval t p flowing between 850 and 700 ° C. is greater than 3 s, in order to obtain a precipitation of precipitates K, then coil the sheet at a temperature T b o b between 500 and 700 0 C.
Selon un mode particulier, la coulée est effectuée directement sous forme de brames minces ou de bandes minces entre cylindres contra-rotatifs. L'invention a également pour objet un procédé de fabrication d'une tôle en acier laminée à froid et recuite selon lequel on approvisionne une tôle d'acier laminée à chaud fabriquée selon un des modes ci-dessus, puis on lamine à froid la tôle avec un taux de réduction compris entre 30 et 90%, de façon à obtenir une tôle laminée à froid. On chauffe ensuite la tôle laminée à froid à une température T' avec une vitesse V0 supérieure à 3°C/s, puis on refroidit la tôle à une vitesse VR inférieure à 100°C/s, la température T' et la vitesse VR étant choisies de façon à obtenir une recristallisation complète, une fraction linéaire f de précipités intergranulaires K inférieure à 30% et une teneur en carbone en solution solide inférieure à 0,005% en poids. On chauffe préférentiellement la tôle laminée à froid à une température T' comprise entre 750 et 9500C.In a particular embodiment, the casting is carried out directly in the form of thin slabs or thin strips between contra-rotating rolls. The invention also relates to a method of manufacturing a cold-rolled and annealed steel sheet according to which a hot-rolled steel sheet manufactured according to one of the above modes is supplied, then the sheet is cold-rolled. with a reduction ratio of between 30 and 90%, so as to obtain a cold-rolled sheet. The cold-rolled sheet is then heated to a temperature T 'with a speed V 0 greater than 3 ° C./s, then the sheet is cooled to a speed VR less than 100 ° C./s, the temperature T' and the speed V R being selected so as to obtain complete recrystallization, a linear fraction f of intergranular precipitates K of less than 30% and a carbon content in solid solution of less than 0.005% by weight. The cold-rolled sheet is preferably heated to a temperature T 'of between 750 and 950 ° C.
Selon un mode particulier de fabrication d'une tôle laminée à froid et recuite, on approvisionne une tôle de composition : 0,010 % < C ≤ 0,15%, 0,2% < Mn < 1%, Si < 1 ,5%, 6% ≤AI < 10%, 0,020% ≤ Ti < 0,5%, S < 0,050%, P < 0, 1% et, à titre optionnel, un ou plusieurs éléments choisis parmi : Cr ≤ 1%, Mo < 1%, Ni < 1%, Nb < 0.1 %, V ≤ 0,2%, B < 0,01%, le reste de la composition étant constitué de fer et d'impuretés inévitables résultant de l'élaboration, et on chauffe la tôle laminée à froid à une température T choisie de façon à éviter la dissolution de précipités K.According to a particular method of manufacturing a cold-rolled and annealed sheet, a sheet of composition is supplied: 0.010% <C ≤ 0.15%, 0.2% <Mn <1%, Si <1.5%, 6% ≤AI <10%, 0.020% ≤ Ti <0.5%, S <0.050%, P <0.1% and, optionally, one or more elements selected from: Cr ≤ 1%, Mo <1 %, Ni <1%, Nb <0.1%, V ≤ 0.2%, B <0.01%, the remainder of the composition consisting of iron and unavoidable impurities resulting from the preparation, and heating the cold-rolled sheet at a temperature T chosen so as to avoid the dissolution of precipitates K.
Selon un mode particulier, on approvisionne une tôle de composition ci- dessus et on chauffe la tôle laminée à froid à une température T' comprise entre 750 et 8000C. L'invention a également pour objet l'utilisation de tôles d'acier selon l'un des modes ci-dessus ou fabriquées selon l'un des modes ci-dessus pour la fabrication de pièces de peau ou de pièces structurales dans le domaine automobile.According to a particular mode, supplying a sheet of composition above and heating the cold-rolled sheet to a temperature T 'of between 750 and 800 ° C. The invention also relates to the use of steel sheets according to one of the above modes or manufactured in one of the above modes for the manufacture of skin parts or structural parts in the automotive field.
D'autres caractéristiques et avantages de l'invention apparaîtront au cours de la description ci-dessous, donnée à titre d'exemple et faite en référence aux figures annexées ci-jointes selon lesquelles :Other features and advantages of the invention will become apparent from the description below, given by way of example and with reference to the appended accompanying figures in which:
- La figure 1 définit schématiquement la fraction linéaire f de joints de grains ferritiques comportant une précipitation intergranulaireFIG. 1 schematically defines the linear fraction f of ferritic grain boundaries with intergranular precipitation
- La figure 2 présente la microstructure d'une tôle d'acier laminée à chaud selon l'invention. - La figure 3 présente la microstructure d'une tôle d'acier laminée à chaud fabriquée selon des conditions ne satisfaisant pas à l'invention- Figure 2 shows the microstructure of a hot-rolled steel sheet according to the invention. FIG. 3 shows the microstructure of a hot-rolled steel sheet manufactured according to conditions that do not satisfy the invention
- Les figures 4 et 5 illustrent la microstructure de deux tôles laminées à froid et recuites selon l'invention.- Figures 4 and 5 illustrate the microstructure of two cold-rolled sheets and annealed according to the invention.
- La figure 6 présente la microstructure d'une tôle d'acier laminée à froid et recuite fabriquée selon des conditions ne satisfaisant pas à l'inventionFIG. 6 shows the microstructure of a cold-rolled and annealed steel sheet manufactured according to conditions that do not satisfy the invention
La présente invention est relative à des aciers présentant une densité réduite, inférieure à 7,3 environ, tout en conservant des caractéristiques d'usage satisfaisantes. L'invention est notamment relative à un procédé de fabrication permettant de contrôler la précipitation de carbures intermétalliques, la microstructure, et la texture dans des aciers comportant notamment des combinaisons particulières de carbone, d'aluminium et de titane. En ce qui concerne la composition chimique de l'acier, le carbone joue un rôle important sur la formation de la microstructure et sur les propriétés mécaniques :The present invention relates to steels having a reduced density, less than about 7.3, while retaining satisfactory use characteristics. The invention relates in particular to a manufacturing method for controlling the precipitation of intermetallic carbides, the microstructure, and the texture in steels including particular combinations of carbon, aluminum and titanium. With regard to the chemical composition of steel, carbon plays an important role in the formation of the microstructure and in the mechanical properties:
- Selon l'invention, la teneur en carbone est comprise entre 0,001% et 0,15% : au dessous de 0,001%, on ne peut obtenir un durcissement significatif. Lorsque la teneur en carbone est supérieure à 0,15%, l'aptitude au laminage à froid des aciers est faible.According to the invention, the carbon content is between 0.001% and 0.15%: below 0.001%, significant curing can not be obtained. When the carbon content is greater than 0.15%, the cold rollability of the steels is low.
- Lorsque la teneur en manganèse excède 1%, il existe un risque de stabilisation de l'austénite résiduelle à température ambiante en raison du caractère gammagène de cet élément. Les aciers selon l'invention ont une microstructure ferritique à température ambiante. Différents modes particuliers de l'invention peuvent être mis en œuvre, en fonction de la teneur en carbone et en manganèse de l'acier :- When the manganese content exceeds 1%, there is a risk of stabilization of the residual austenite at room temperature because of the gamma-genic nature of this element. The steels according to the invention have a ferritic microstructure at ambient temperature. Different particular embodiments of the invention may be implemented, depending on the carbon and manganese content of the steel:
- Lorsque la teneur en carbone est comprise entre 0,001 et 0,010% et lorsque la teneur en manganèse est inférieure ou égale à 0,2%, la résistance Rm minimale obtenue est de 400MPa.- When the carbon content is between 0.001 and 0.010% and when the manganese content is less than or equal to 0.2%, the minimum resistance R m obtained is 400MPa.
- Lorsque la teneur en carbone est supérieure à 0,010% et inférieure ou égale à 0,15%, et lorsque la teneur en manganèse est supérieure à 0,2% et inférieure ou égale à 1%, la résistance minimale obtenue est de 600 MPa. Dans les gammes des teneurs en carbone présentées ci-dessus, les inventeurs ont mis en évidence que cet élément contribuait à un durcissement important par une précipitation de carbures (TiC ou précipités kappa) et par un affinement du grain ferritique. L'addition de carbone ne conduit qu'à une faible perte de ductilité si la précipitation de carbures n'est pas intergranulaire ou si le carbone n'est pas en solution solide. Dans ces gammes de composition, l'acier a une matrice ferritique à toute température lors du cycle de fabrication, c'est à dire dès la solidification à partir de la coulée. - Au même titre que l'aluminium, le silicium est un élément permettant de réduire la densité de l'acier. Cependant, une addition excessive de silicium, au delà de 1 ,5%, provoque la formation d'oxydes fortement adhérents et l'apparition éventuelle de défauts de surface, conduisant notamment à un manque de mouillabilité dans les opérations de galvanisation au trempé. De plus, cette addition excessive diminue la ductilité.- When the carbon content is greater than 0,010% and less than or equal to 0,15%, and when the manganese content is greater than 0,2% and less than or equal to 1%, the minimum resistance obtained is 600 MPa . In the ranges of carbon contents presented above, the inventors have demonstrated that this element contributes to a significant hardening by a precipitation of carbides (TiC or kappa precipitates) and a refinement of the ferritic grain. The addition of carbon only leads to a small loss of ductility if the precipitation of carbides is not intergranular or if the carbon is not in solid solution. In these composition ranges, the steel has a ferritic matrix at any temperature during the manufacturing cycle, that is to say from the solidification from the casting. - As with aluminum, silicon is an element that reduces the density of steel. However, an excessive addition of silicon, beyond 1, 5%, causes the formation of strongly adherent oxides and the possible appearance of surface defects, leading in particular to a lack of wettability in dip galvanizing operations. In addition, this excessive addition decreases ductility.
- L'aluminium est un élément important de l'invention : lorsque sa teneur est inférieure à 6% en poids, une réduction suffisante de la densité ne peut être obtenue. Lorsque sa teneur est supérieure à 10%, il existe un risque de formation de phases intermétalliques fragilisantes Fβ3AI et FeAI.Aluminum is an important element of the invention: when its content is less than 6% by weight, a sufficient reduction of the density can not be obtained. When its content is greater than 10%, there is a risk of formation of embrittling intermetallic phases Fβ 3 AI and FeAI.
Préférentiellement, la teneur en aluminium est comprise entre 7,5 et 10% : au sein de cette gamme, la densité de la tôle est inférieure à 7,1 environ. Préférentiellement, la teneur en aluminium est comprise entre 7,5 et 8,5% : dans cette gamme, on obtient un allégement satisfaisant sans diminution de la ductilité.Preferably, the aluminum content is between 7.5 and 10%: within this range, the density of the sheet is less than about 7.1. Preferably, the aluminum content is between 7.5 and 8.5%: in this range, satisfactory lightening is obtained without reducing the ductility.
- L'acier contient également une teneur minimale en titane de 0,020% qui contribue à limiter la teneur en carbone en solution solide en quantité inférieure à 0,005% en poids, grâce à une précipitation de TiC. Le carbone en solution solide a un effet néfaste sur la ductilité du fait qu'il réduit la mobilité des dislocations. Au delà de 0,5% de titane, la précipitation de carbures de titane intervient en quantité trop importante, et la ductilité est réduite.The steel also contains a minimum titanium content of 0.020% which contributes to limiting the carbon content in solid solution in an amount of less than 0.005% by weight, thanks to a precipitation of TiC. Carbon in solid solution has a deleterious effect on ductility because it reduces the mobility of dislocations. Beyond 0.5% titanium, the precipitation of titanium carbides occurs in too large a quantity, and the ductility is reduced.
- Une addition éventuelle de bore limitée à 0,010% contribue également à une réduction du carbone en solution solide.- A possible addition of boron limited to 0.010% also contributes to a reduction of carbon in solid solution.
- La teneur en soufre est inférieure à 0,050% de façon à limiter une précipitation éventuelle de TiS qui diminuerait la ductilité.- The sulfur content is less than 0.050% so as to limit a possible precipitation of TiS which would reduce the ductility.
- Pour des raisons de ductilité à chaud, la teneur en phosphore est également limitée à 0,1%.For reasons of hot ductility, the phosphorus content is also limited to 0.1%.
A titre optionnel, l'acier peut également contenir, seuls ou en combinaison :As an option, steel may also contain, alone or in combination:
- du chrome, du molybdène, ou du nickel en quantité inférieure ou égale à 1%. Ces éléments apportent un durcissement complémentaire par solution solide. - Des éléments de micro-alliage, comme le niobium et le vanadium en quantité respectivement inférieure à 0,1 et 0,2% en poids, peuvent être ajoutés pour obtenir un durcissement complémentaire par précipitation. Le reste de la composition est constitué de fer et des impuretés inévitables qui résultent de l'élaboration.chromium, molybdenum, or nickel in an amount of less than or equal to 1%. These elements provide additional hardening by solid solution. Micro-alloy elements, such as niobium and vanadium in an amount of less than 0.1 and 0.2% by weight respectively, can be added to obtain a complementary hardening by precipitation. The rest of the composition consists of iron and unavoidable impurities that result from the elaboration.
La structure des aciers selon l'invention comporte une distribution homogène de grains ferritiques fortement désorientés : la désorientation forte entre grains voisins permet d'éviter le défaut de chiffonnage : ce défaut se caractérise, lors de la mise en forme à froid de tôles, par l'apparition localisée et prématurée de bandes suivant le sens de laminage, formant un relief. Ce phénomène est dû à la présence de groupement de grains recristallisés et faiblement désorientés, car provenant d'un même grain originel avant recristallisation. Une structure sensible au chiffonnage est caractérisée par une distribution spatiale de texture. Lorsque le phénomène de chiffonnage est présent, les propriétés mécaniques en sens travers (notamment l'allongement uniforme) et l'aptitude à la mise en forme sont fortement réduites. Les aciers selon l'invention ne présentent pas de sensibilité au chiffonnage lors de la mise en forme, en raison de leur texture favorable. Selon une forme de l'invention, la microstructure à température ambiante des aciers est constituée d'une matrice de ferrite équiaxe dont la taille de grain moyenne est inférieure à 50 micromètres. L'aluminium est majoritairement en solution solide dans cette matrice à base de fer. Ces aciers contiennent des précipités kappa (« K ») qui sont une phase intermétallique ternaire Fe3AICx. La présence de ces précipités dans la matrice ferritique conduit à un durcissement important. Ces précipités K ne doivent cependant pas être présents sous forme d'une précipitation intergranulaire marquée sous peine d'une réduction importante de la ductilité : les inventeurs ont mis en évidence que la ductilité était réduite lorsque la fraction linéaire de joints de grains ferritiques qui présentent une précipitation K, était supérieure ou égale à 30%. La définition de cette fraction linéaire f est donnée à la figure 1 : Si l'on considère un grain particulier dont le contour est limité par des joints de grains successifs de longueur Li, L2, .. U, les observations par microscopie montrent que ce grain peut comporter des précipités K le long des joints sur une longueur d-i, ..dj... En considérant une surface (S) statistiquement représentative de la microstructure, par exemple composée de plus de 50 grains, on définit la fraction linéaire comportant des précipités K par l'expression f :The structure of the steels according to the invention comprises a homogeneous distribution of highly disoriented ferritic grains: the strong disorientation between neighboring grains makes it possible to avoid the crimping defect: this defect is characterized, during the cold forming of sheets, by the localized and premature appearance of strips in the direction of rolling, forming a relief. This phenomenon is due to the presence of recrystallized and weakly disoriented grain groups, since they originate from the same original grain before recrystallization. A scuff sensitive structure is characterized by spatial texture distribution. When the scuffing phenomenon is present, the cross-machine mechanical properties (especially the uniform elongation) and the formability are greatly reduced. The steels according to the invention do not show any sensitivity to creasing during the shaping, because of their favorable texture. According to one form of the invention, the microstructure at ambient temperature of the steels consists of an equiaxed ferrite matrix whose average grain size is less than 50 micrometers. Aluminum is mainly in solid solution in this matrix based on iron. These steels contain kappa precipitates ("K") which are a ternary Fe 3 AIC x intermetallic phase. The presence of these precipitates in the ferritic matrix leads to a significant hardening. These precipitates K must not, however, be present in the form of a marked intergranular precipitation under penalty of a significant reduction of the ductility: the inventors have shown that the ductility was reduced when the linear fraction of ferritic grain boundaries which present K precipitation was greater than or equal to 30%. The definition of this linear fraction f is given in FIG. 1: If we consider a particular grain whose contour is limited by successive grain boundaries of length Li, L 2 ,. the observations by microscopy show that this grain may comprise precipitates K along the joints over a length di, ..dj ... Considering a surface (S) statistically representative of the microstructure, for example composed of more than 50 grains, the linear fraction containing precipitates K is defined by the expression f:
∑di désigne la longueur totale des joints de grains comportant desΣdi denotes the total length of the grain boundaries with
(S) précipités K, relativement à la surface (S) considérée. ∑Li représente la(S) precipitated K, relative to the surface (S) considered. ΣLi represents the
(S) longueur totale des joints de grains relativement à la surface (S) considérée. L'expression f traduit donc le taux de recouvrement des joints de grains ferritiques par une précipitation K.(S) total length of the grain boundaries relative to the surface (S) considered. The expression f thus translates the degree of recovery of the ferritic grain boundaries by a precipitation K.
Selon une autre forme de l'invention, le grain ferritique n'est pas équiaxe mais sa taille moyenne d|V est inférieure à 100 micromètres. d|V désigne la taille de grain mesurée par la méthode des intercepts linéaires sur une surface (S) représentative perpendiculaire à la direction transverse par rapport au laminage. La mesure de div est effectuée selon la direction perpendiculaire à l'épaisseur de la tôle. Cette morphologie de grain non équiaxe, présentant un allongement dans le sens du laminage, peut être par exemple présente sur des tôles d'acier laminées à chaud selon l'invention. La mise en œuvre du procédé de fabrication d'une tôle laminée à chaud selon l'invention est la suivante :According to another form of the invention, the ferritic grain is not equiaxed but its average size d | V is less than 100 micrometers. d | V denotes the grain size measured by the method of linear intercepts on a representative surface (S) perpendicular to the direction transverse to the rolling. The measure of div is made in the direction perpendicular to the thickness of the sheet. This non-equiaxial grain morphology, having an elongation in the direction of rolling, may for example be present on hot-rolled steel sheets according to the invention. The implementation of the method for manufacturing a hot-rolled sheet according to the invention is as follows:
- On approvisionne un acier de composition selon l'invention.- A steel composition is provided according to the invention.
- On procède à la coulée d'un demi-produit à partir de cet acier. Cette coulée peut être réalisée en lingots, ou en continu sous forme de brames d'épaisseur de l'ordre de 200mm. On peut également effectuer la coulée sous forme de brames minces de quelques dizaines de millimètres d'épaisseur, ou de bandes minces, entre cylindres d'acier contra-rotatifs. Ce mode de fabrication sous forme de produits minces est particulièrement avantageux, car il permet d'obtenir plus facilement une structure fine qui favorise la réalisation de l'invention comme on le verra plus loin. Au moyen de ses connaissances générales, l'homme du métier saura déterminer les conditions de coulée satisfaisant à la fois la nécessité d'obtenir une structure fine et équiaxe après la coulée, et celle de satisfaire les exigences usuelles d'une coulée industrielle.- It proceeds to the casting of a half-product from this steel. This casting may be carried out in ingots, or continuously in the form of slabs of thickness of the order of 200 mm. The casting can also be carried out in the form of thin slabs of a few tens of millimeters thick, or thin strips, between contra-rotating steel rolls. This method of manufacture in the form of thin products is particularly advantageous because it makes it easier to obtain a fine structure which favors the production of the invention as will be seen later. By means of his general knowledge, the skilled person will determine the casting conditions satisfying both the need to obtain a fine and equiaxed structure after casting, and that of meeting the usual requirements of an industrial casting.
Les demi-produits coulés sont tout d'abord portés à une température supérieure à 11500C pour atteindre en tout point une température favorable aux déformations élevées que va subir l'acier lors des différentes étapes de laminage. Naturellement, dans le cas d'une coulée directe de brames minces ou de bandes minces entre cylindres contra-rotatifs, l'étape de laminage à chaud de ces demi-produits débutant à plus de 11500C peut se faire directement après coulée si bien qu'une étape de réchauffage intermédiaire n'est pas nécessaire dans ce cas. A la suite de nombreux essais, les inventeurs ont mis en évidence qu'il était possible d'éviter le problème de chiffonnage et d'obtenir une très bonne emboutissabilité et une bonne ductilité, au moyen du procédé de fabrication comportant les étapes suivantes :The cast semi-finished products are first brought to a temperature above 1150 ° C. in order to reach at all points a temperature favorable to the high deformations which the steel will undergo during the various rolling steps. Naturally, in the case of a direct casting of thin slabs or thin strips between contra-rotating rolls, the hot rolling step of these semi-products starting at more than 1150 ° C. can be done directly after casting so well. that an intermediate heating step is not necessary in this case. After numerous tests, the inventors have demonstrated that it was possible to avoid the problem of scouring and to obtain very good drawability and good ductility, by means of the manufacturing process comprising the following steps:
- On lamine à chaud le demi-produit pour obtenir une tôle, par une succession d'étapes de laminage. Chacune des étapes correspond à une réduction d'épaisseur du produit par le passage au sein de cylindres de laminoir. Dans des conditions industrielles, ces étapes sont réalisées lors du dégrossissage du demi-produit sur un train à bandes. Le taux de réduction associé à chacune de ces étapes est défini par : (épaisseur du demi-produit après étape de laminage- épaisseur avant laminage)/- The semi-finished product is hot rolled to obtain a sheet, by a succession of rolling steps. Each of the steps corresponds to a reduction in the thickness of the product by passing through rolling mill rolls. Under industrial conditions, these steps are performed when roughing the semi-finished product on a band train. The reduction rate associated with each of these stages is defined by: (thickness of the half-product after rolling step-thickness before rolling) /
(épaisseur avant laminage) Selon l'invention, au moins deux de ces étapes sont réalisées à des températures supérieures à 10500C, le taux de réduction de chacune d'elles est supérieur ou égal à 30%. L'intervalle de temps tj entre chacune des déformations de taux supérieur à 30% et la déformation ultérieure est supérieur ou égal à 10 s de façon à obtenir une recristallisation totale à l'issue de cet intervalle de temps tj. Les inventeurs ont mis en évidence que cette combinaison particulière de conditions conduisait à un affinement très important de la structure à chaud. On promeut ainsi une recristallisation grâce à des températures de laminage supérieures à la température de non-recristallisation Tnr. Les inventeurs ont également mis en évidence qu'une structure initiale fine, telle que celle obtenue après une coulée directe, était favorable pour accélérer la recristallisation.(thickness before rolling) According to the invention, at least two of these steps are performed at temperatures above 1050 ° C., the reduction ratio of each of them is greater than or equal to 30%. The time interval tj between each of the rate deformations greater than 30% and the subsequent deformation is greater than or equal to 10 s so as to obtain a total recrystallization at the end of this time interval tj. The inventors have demonstrated that this particular combination of conditions led to a very important refinement of the hot structure. We thus promotes recrystallization thanks to rolling temperatures higher than the non-recrystallization temperature Tnr. The inventors have also demonstrated that a fine initial structure, such as that obtained after direct casting, was favorable to accelerate the recrystallization.
- On achève le laminage à une température TFL supérieure ou égale à 9000C, de façon à obtenir une recristallisation complète.- The rolling is completed at a TFL temperature greater than or equal to 900 0 C, so as to obtain a complete recrystallization.
On refroidit ensuite la tôle obtenue : les inventeurs ont mis en évidence qu'une précipitation particulièrement efficace de précipités K et de carbures TiC était obtenue lorsque l'intervalle de temps tp s'écoulant au refroidissement entre 850 et 7000C était supérieur à 3 s. On obtient de la sorte une précipitation intense favorable au durcissement. - On bobine ensuite la tôle à une température TbOb comprise entre 500 et 7000C. Cette étape achève la précipitation de TiC. A ce stade, on obtient ainsi une tôle laminée à chaud dont l'épaisseur va par exemple de 2 à 6mm. Si l'on souhaite fabriquer une tôle d'épaisseur plus faible, par exemple de 0,6 à 1 ,5mm, le procédé de fabrication est le suivant :The sheet obtained is then cooled: the inventors have demonstrated that a particularly effective precipitation of precipitates K and TiC carbides was obtained when the time interval t p flowing on cooling between 850 and 700 ° C. was greater than 3 sec. In this way, an intense precipitation is obtained which is favorable to hardening. - The sheet is then reeled at a temperature T bOb between 500 and 700 0 C. This step completes the precipitation of TiC. At this stage, a hot-rolled sheet is obtained, the thickness of which is, for example, from 2 to 6 mm. If it is desired to manufacture a sheet of lower thickness, for example from 0.6 to 1.5 mm, the manufacturing process is as follows:
- On approvisionne une tôle laminée à chaud, fabriquée selon le procédé décrit ci-dessus. Naturellement, si l'état de surface de la tôle l'exige, on effectuera un décapage au moyen d'un procédé connu en soi.- A hot-rolled sheet is supplied, manufactured according to the method described above. Naturally, if the surface state of the sheet requires it, stripping will be carried out by means of a method known per se.
- On effectue ensuite un laminage à froid, le taux de réduction étant compris entre 30 et 90%- Cold rolling is then carried out, the reduction rate being between 30 and 90%
- On chauffe ensuite la tôle laminée à froid avec une vitesse de réchauffage V0 supérieure à 3°C/s, ceci afin d'éviter une restauration qui diminuerait la capacité à la recristallisation ultérieure. Le réchauffage est effectué jusqu'à une température de recuit T' qui sera choisie de façon à obtenir une recristallisation complète de la structure initiale fortement écrouie. On refroidit ensuite la tôle à une vitesse VR inférieure à 100°C/s de façon à ne pas provoquer une éventuelle fragilisation par un excès de carbone en solution solide. Ce résultat est particulièrement surprenant dans la mesure où l'on pouvait penser qu'une vitesse de refroidissement rapide serait favorable pour réduire une précipitation fragilisante. Or les inventeurs ont mis en évidence qu'un refroidissement lent, à une vitesse de refroidissement inférieure à 100°C/s, conduisait une précipitation importante de carbures qui réduisait ainsi la teneur en carbone en solution solide: cette précipitation a pour effet d'augmenter la résistance sans conséquence néfaste sur la ductilité. On choisira la température de recuit T et la vitesse VR de façon à obtenir sur le produit final :- The cold-rolled sheet is then heated with a heating rate V 0 greater than 3 ° C./s, in order to avoid a restoration which would reduce the capacity for subsequent recrystallization. Reheating is performed up to an annealing temperature T 'which will be chosen so as to obtain a complete recrystallization of the initial structure hardened. The sheet is then cooled at a speed V R of less than 100 ° C./s so as not to cause any embrittlement by excess of carbon in solid solution. This result is particularly surprising in that it could be thought that a rapid cooling rate would be favorable to reduce embrittling precipitation. However, the inventors have shown that slow cooling at a cooling rate less than 100 ° C / s, led a significant precipitation of carbides which reduced the carbon content in solid solution: this precipitation has the effect of increasing the resistance without adverse effect on ductility. We will choose the annealing temperature T and the speed V R so as to obtain on the final product:
- Une recristallisation complète- A complete recrystallization
- Une fraction linéaire f de précipités intergranulaires K inférieure à 30%A linear fraction f of intergranular precipitates K less than 30%
- Une teneur en carbone en solution solide inférieure à 0,005%. On choisira préférentiellement une température T' comprise entre 750 et 95O0C pour obtenir une recristallisation complète.- A solid solution carbon content of less than 0.005%. Preferably be chosen a temperature T 'between 750 and 95o 0 C to achieve complete recrystallization.
Plus particulièrement, lorsque la teneur en carbone est supérieure à 0,010 % et inférieure ou égale à 0,15% et lorsque la teneur en manganèse est supérieure à 0,2% et inférieure ou égale à 1%, on choisira la température T' de façon à éviter en outre la dissolution de précipités K présents avant le recuit. En effet, si ces précipités sont dissous, la précipitation ultérieure au refroidissement lent interviendra sous forme intergranulaire fragilisante : une température de recuit trop importante conduirait à la redissolution des précipités K formés lors de la fabrication de la tôle laminée à chaud et diminuerait la résistance mécanique. A cette fin, on choisira préférentiellement une température T' comprise entre 750 et 8000C. A titre d'exemple non limitatif, les résultats suivants vont montrer les caractéristiques avantageuses conférées par l'invention. Exemple 1 :Tôles laminées à chaud On a élaboré des aciers par coulée sous la forme de demi-produits d'épaisseur de 50 mm environ. Leurs compositions, exprimées en pourcentage pondéral, figurent au tableau 1 ci-dessous. More particularly, when the carbon content is greater than 0.010% and less than or equal to 0.15% and when the manganese content is greater than 0.2% and less than or equal to 1%, the temperature T 'of in addition to preventing the dissolution of precipitates K present before the annealing. In fact, if these precipitates are dissolved, the subsequent precipitation after slow cooling will take place in embrittling intergranular form: a too high annealing temperature would lead to the redissolution of the precipitates K formed during the manufacture of the hot-rolled sheet and reduce the mechanical strength. . For this purpose, a temperature T 'will preferably be chosen between 750 and 800 ° C. By way of non-limiting example, the following results will show the advantageous characteristics conferred by the invention. Example 1: Hot rolled sheets Steels were produced by casting in the form of half-products with a thickness of about 50 mm. Their compositions, expressed in weight percent, are shown in Table 1 below.
Tableau 1 Compositions d'aciers (% poids). I= Selon l'invention. R= référence Valeurs soulignées : Non conforme à l'invention.Table 1 Compositions of steel (% by weight). I = according to the invention. R = reference Underlined values: Not in accordance with the invention.
Les demi-produits ont été réchauffés à une température de 122O0C et laminés à chaud pour obtenir une tôle d'une épaisseur de 3,5 mm environ. A partir d'une même composition, certains aciers ont fait l'objet de différentes conditions de laminage à chaud. Les références 11-a, 11-b, 11-c, 11-d, 11-e désignent par exemple cinq tôles d'aciers fabriquées selon des conditions différentes à partir de la composition 11. Pour les aciers 11 à 13, le tableau 2 détaille les conditions des étapes successives de laminage à chaud :The half-products were heated to a temperature of 122O 0 C and hot rolled to obtain a sheet of a thickness of about 3.5 mm. From the same composition, some steels have been subjected to different hot rolling conditions. The references 11-a, 11-b, 11-c, 11-d, 11-e designate for example five steel sheets manufactured under different conditions from the composition 11. For the steels 11 to 13, the table 2 details the conditions of the successive stages of hot rolling:
- Le nombre N d'étapes de laminage effectuées à une température de laminage à chaud supérieure à 10500CThe number N of rolling steps carried out at a hot rolling temperature greater than 1050 ° C.
- Parmi celles-ci, le nombre Ni d'étapes de laminage dont le taux de réduction est supérieur à 30%- Of these, the number Ni of rolling stages whose reduction rate is greater than 30%
- Le temps tj s'écoulant entre chacune des étapes Nj, et l'étape de laminage succédant immédiatement à chacune de celles-ciThe time tj flowing between each of the steps Nj, and the rolling step immediately succeeding each of these
- La température de fin de laminage TFL- The end temperature of rolling TFL
- L'intervalle de temps tp s'écoulant au refroidissement entre 850 et 7000C- The time interval t p flowing on cooling between 850 and 700 0 C
- La température de bobinage Tbob - Tbob winding temperature
Tableau 2 : Conditions de fabrication lors du laminage à chaudTable 2: Manufacturing conditions during hot rolling
I= Selon l'invention. R= référence Valeurs soulignées : Non conformes à l'invention.I = according to the invention. R = reference Underlined values: Not according to the invention.
Le tableau 3 présente la densité mesurée sur les tôles du tableau 2 et certaines caractéristiques mécaniques et microstructurales. On a ainsi mesuré, en sens travers par rapport au laminage, la résistance Rm, l'allongement uniforme Au, l'allongement à rupture At. On a également mesuré la taille de grains div par la méthode des intercepts linéaires selon la norme NF EN ISO 643 sur une surface perpendiculaire à la direction transverse par rapport au laminage. La mesure de div a été effectuée selon la direction perpendiculaire à l'épaisseur de la tôle Dans le but d'obtenir des propriétés mécaniques accrues, on recherche plus particulièrement une taille de grain div inférieure à 100 micromètres. Table 3 shows the density measured on the plates of Table 2 and certain mechanical and microstructural characteristics. The resistance Rm, the uniform elongation A u , the elongation at break A t, have thus been measured in the cross-machine direction with respect to rolling. The grain size div was also measured by the linear intercepts method according to the NF EN ISO 643 standard on a surface perpendicular to the direction transverse to the rolling. The measure of div was made in the direction perpendicular to the thickness of the sheet. In order to obtain increased mechanical properties, a grain size div less than 100 microns is particularly desired.
Tableau 3 : Propriétés des tôles laminées à chaud obtenues à partir des aciers 11 et 13. I= Selon l'invention. R= référence n.d= non déterminé Valeurs soulignées : Non conformes à l'invention.Table 3: Properties of hot-rolled sheets obtained from steels 11 and 13. I = According to the invention. R = reference n.d = not determined Underlined values: Not according to the invention.
Les tôles d'acier selon l'invention, dont la microstructure est illustrée par exemple à la figure 2 pour la tôle Hd, sont caractérisées par une taille de grain diV inférieure à 100 micromètres et présentent une résistance mécanique allant de 505 à 645 MPa. Les tôles 11b et 11e ont été laminées avec un temps interpasse trop court. Leur structure est alors grossière et non recristallisée ou insuffisamment recristallisée comme le montre la figure 3 relative à la tôle 11e. En conséquence, la ductilité est diminuée et la tôle est plus sensible au défaut de chiffonnage. Des conclusions similaires peuvent être tirées pour la tôle 13b.The steel sheets according to the invention, the microstructure of which is illustrated for example in Figure 2 for the sheet Hd, are characterized by a grain size d IV less than 100 microns and have a mechanical strength ranging from 505-645 MPa . The sheets 11b and 11e were laminated with a time interpasse too short. Their structure is then coarse and not recrystallized or insufficiently recrystallized as shown in Figure 3 relating to the sheet 11e. As a result, the ductility is decreased and the sheet is more sensitive to the lack of creasing. Similar conclusions can be drawn for sheet 13b.
La tôle 11c a été laminée avec un nombre insuffisant d'étapes de laminage avec un taux supérieur à 30%, un temps interpasse et un intervalle de temps tp trop courts. Les conséquences sont identiques à celles notées sur les tôles 11b et 11e. L'intervalle de temps tp étant trop faible, une précipitation durcissante de précipités K et de carbures TiC ne se produit que partiellement, ce qui ne permet pas de tirer le plein parti des possibilités de durcissement.The sheet 11c was rolled with an insufficient number of rolling steps with a rate greater than 30%, a time interpasse and a time interval t p too short. The consequences are identical to those noted on plates 11b and 11e. Since the time interval t p is too low, a hardening precipitation of K precipitates and TiC carbides occurs only partially, which makes it impossible to take full advantage of the curing possibilities.
Les demi-produits réalisés à partir des aciers de référence R1 à R6 ont été laminés pour fabriquer des tôles laminées à chaud dans des conditions de fabrication identiques à celles de l'acier I3a du tableau 2. Les propriétés obtenues sur ces tôles sont portées au tableau 4. The semi-finished products made from the reference steels R1 to R6 were rolled to produce hot rolled sheets under manufacturing conditions identical to those of the steel I3a of Table 2. The properties obtained on these sheets are brought to table 4.
Tableau 4 : Propriétés mécaniques des tôles laminées à chaud obtenues à partir des aciers R1 à R6. I= Selon l'invention. R= référence n.d.= non déterminéTable 4: Mechanical properties of hot-rolled sheets obtained from steels R1 to R6. I = according to the invention. R = reference n.d. = not determined
Valeurs soulignées : Non conformes à l'invention.Underlined Values: Not in accordance with the invention.
L'acier R1 possède une teneur insuffisante en titane ce qui conduit à une teneur en carbone en solution solide trop importante : l'aptitude au pliage est alors réduite.The steel R1 has an insufficient titanium content which leads to a solid solution carbon content that is too high: the folding ability is then reduced.
L'acier R2 possède une teneur en aluminium insuffisante ce qui ne permet pas d'obtenir une densité inférieure à 7,3.Steel R2 has an insufficient aluminum content which does not allow to obtain a density lower than 7.3.
Les aciers R3, R4, R5 et R6 contiennent une teneur trop importante en aluminium et éventuellement en carbone : leur ductilité est réduite en raison de la précipitation excessive de phases intermétalliques ou de carburesR3, R4, R5 and R6 steels contain too much aluminum and possibly carbon: their ductility is reduced due to the excessive precipitation of intermetallic phases or carbides
Exemple 2 : Tôles laminées à froid et recuitesExample 2: Cold-rolled and annealed sheets
A partir des tôles d'aciers laminées à chaud 11 -a et 13-a (selon l'invention) et 11-c et l-3b (ne satisfaisant pas aux conditions de l'invention), on a effectué un laminage à froid avec une réduction de 75% pour obtenir des tôles deFrom hot-rolled steel sheets 11a and 13a (according to the invention) and 11c and 1-3b (not satisfying the conditions of the invention), cold rolling was carried out. with a reduction of 75% to obtain plate of
0,9mm d'épaisseur environ. L'aptitude au laminage à froid a été relevée durant cette étape. On a ensuite effectué un recuit caractérisé par une vitesse de chauffage Vc=10°C/s. Les températures de recuit T' et les vitesses de refroidissement VR ont été portées au tableau 5. Dans ces conditions, le recuit entraîne une recristallisation complète.About 0.9mm thick. The cold rolling ability was noted during this step. An annealing characterized by a heating rate V c = 10 ° C./s. The annealing temperatures T 'and the cooling rates V R are given in Table 5. Under these conditions, annealing results in complete recrystallization.
A partir d'une même tôle laminée à chaud, certains aciers ont fait l'objet de différentes conditions de laminage à froid et de recuit. Les références I3a1 , I3a2, I3a3, I3a4, désignent par exemple quatre tôles d'aciers fabriquées selon des conditions différentes de laminage à froid et de recuit à partir de la tôle laminée à chaud 13a.From the same hot-rolled sheet, some steels have undergone different conditions of cold rolling and annealing. The references I3a1, I3a2, I3a3, I3a4, for example, designate four steel sheets made under different cold rolling conditions and annealing from the hot-rolled sheet 13a.
Tableau 5 : Conditions de fabrication des tôles laminées à froid et recuitesTable 5: Production conditions for cold-rolled and annealed sheets
I= Selon l'invention. R= référence Valeurs soulignées : Non conformes à l'invention.I = according to the invention. R = reference Underlined values: Not according to the invention.
Le tableau 6 présente certaines caractéristiques mécaniques, chimiques, microstructurales et de densité des tôles du tableau 5. On a ainsi mesuré par des essais de traction en sens travers par rapport au laminage, la limite d'élasticité Re1 la résistance Rm, l'allongement uniforme Au, l'allongement à rupture At. Au moyen d'observations par microscopie électronique à balayage, on a relevé la présence éventuelle de facettes de clivage sur les surfaces de rupture des éprouvettes d'essais.Table 6 shows some of the mechanical, chemical, microstructural and density characteristics of the sheets of Table 5. The yield strength Re 1, the resistance Rm, the resistance, was measured by transverse tensile tests with respect to rolling. uniform elongation A u , elongation at break At. By means of observations by scanning electron microscopy, it was noted the possible presence of cleavage facets on the rupture surfaces of test specimens.
La teneur en carbone CSOι en solution solide a été également mesurée.The carbon content C SO ι in solid solution was also measured.
L'aptitude au pliage et à l'emboutissage ont été évaluées. On a également relevé la présence éventuelle de chiffonnage consécutif aux déformations.The ability to bend and press was evaluated. It was also noted the possible presence of scuffing consecutive deformations.
La microstructure de ces tôles recristallisées est constituée de ferrite équiaxe dont la taille moyenne de grain dα a été mesurée dans le sens transverse du laminage. On a également mesuré le taux de recouvrement f des joints de grains ferritiques par une précipitation K, au moyen du logiciel d'analyses d'images Aphelion™.The microstructure of these recrystallized sheets consists of equiaxed ferrite whose average α- grain size was measured in the transverse rolling direction. We also measured the recovery rate f of the joints of Ferritic grains by precipitation K, using the Aphelion ™ image analysis software.
Tableau 6 : Propriétés mécaniques des tôles laminées à froid et recuites obtenues à partir des aciers 11 et 13.Table 6: Mechanical properties of cold-rolled and annealed sheets obtained from steels 11 and 13.
I= Selon l'invention. R= référence. N.d. : non déterminéI = according to the invention. R = reference. N.d. : not determined
Valeurs soulignées : Non conformes à l'invention.Underlined Values: Not in accordance with the invention.
Les tôles d'aciers Mal et I3a1 présentent une teneur en carbone en solution îo solide, une taille de grain équiaxe ferritique et un taux de recouvrement f des joints de grains qui satisfont aux conditions de l'invention. Par suite, l'aptitude au pliage, à l'emboutissage, la résistance au chiffonnage de ces tôles, est élevée.The sheets of Mal and I3a1 steels have a solid solution carbon content, a ferritic equiaxed grain size, and a grain boundary coverage rate that satisfies the requirements of the invention. As a result, the ability to bend, stamping, scratch resistance of these sheets, is high.
La figure 4 illustre la microstructure de la tôle d'acier Mal selon l'invention. 15 La figure 5 illustre la microstructure d'une autre tôle d'acier selon l'invention,Figure 4 illustrates the microstructure of the steel sheet Mal according to the invention. FIG. 5 illustrates the microstructure of another steel sheet according to the invention,
I3a1 : on note la présence de précipités K dont une faible quantité seulement est présente sous forme intergranulaire, ce qui permet de conserver une ductilité élevée.I3a1: Note the presence of K precipitates of which only a small amount is present in intergranular form, which allows to maintain a high ductility.
En comparaison, la tôle d'acier I1a2 a été refroidie à une vitesse trop 20 importante après recuit : le carbone est alors totalement en solution solide, ce qui entraine une réduction de ductilité de la matrice se traduisant par la présence locale de plages fragiles sur les faciès de rupture. De même, la tôleIn comparison, the steel sheet I1a2 has been cooled at a too high speed after annealing: the carbon is then completely in solid solution, which leads to a reduction in ductility of the matrix resulting in the local presence of fragile areas on the facies of rupture. Similarly, sheet metal
I3a2 a été refroidie à une vitesse trop importante et conduit également à une teneur excessive en solution solide. La figure 6 illustre la microstructure de la tôle I3a3 : celle-ci a été recuite à une température T' trop importante : les précipités K présents avant le recuit ont été dissous, leur précipitation ultérieure au refroidissement est intervenue sous une forme intergranulaire en quantité excessive. Ceci se traduit par la présence locale de plages fragiles sur les faciès de rupture.I3a2 has been cooled too fast and also leads to an excessive content of solid solution. FIG. 6 illustrates the microstructure of the sheet I3a3: this was annealed at too high a temperature T ': the precipitates K present before the annealing were dissolved, their subsequent precipitation after cooling intervened in an intergranular form in excessive amounts . This results in the local presence of fragile beaches on the fracture facies.
La tôle I3a4 a été également recuite à une température qui entraîne une dissolution partielle des précipités K. La teneur en carbone en solution solide est excessive. La tôle d'acier I1c1 a été fabriquée à partir d'une tôle laminée à chaud ne satisfaisant pas aux conditions de l'invention : la taille de grain équiaxe est trop importante, la résistance au chiffonnage et l'aptitude à l'emboutissage sont insuffisantes.The I3a4 sheet was also annealed at a temperature which causes partial dissolution of the precipitates K. The carbon content in solid solution is excessive. The steel sheet I1c1 was made from a hot-rolled sheet not satisfying the requirements of the invention: the equiaxial grain size is too large, the crimping resistance and the stamping ability are insufficient.
La tôle 13b laminée à chaud, ne satisfaisant pas aux critères de l'invention, n'est pas apte à la déformation puisque des fissures transversales apparaissent lors du laminage à froid.The hot-rolled sheet 13b, which does not satisfy the criteria of the invention, is not suitable for deformation since transverse cracks appear during cold rolling.
Des essais de soudabilité par résistance par points ont été effectués sur la tôle d'acier Mal , soit en soudage homogène (soudage de deux tôles de même composition) soit en soudage hétérogène (soudage avec une tôle d'acier sans interstitiel de composition, exprimée en pourcentage pondéral : 0,002%C, 0,01 %Si, 0,15%Mn, 0,04%AI, 0,015%Nb, 0.026%Ti) Les examens montrent que les joints soudés sont exempts de défauts. Dans le cas de traitement thermique ultérieur des joints soudés, l'addition de 0,096%Ti garantit l'absence de carbone en solution solide en zone affectée par la chaleur. Les aciers selon l'invention présentent une bonne aptitude à la galvanisation en continu, en particulier, lors d'un cycle de recuit à 8000C avec une température de point de rosée supérieure à -2O0C.Spot resistance weldability tests were carried out on the steel sheet Mal, either in homogeneous welding (welding of two sheets of the same composition) or in heterogeneous welding (welding with a sheet of steel without interstitial composition, expressed in weight percent: 0.002% C, 0.01% Si, 0.15% Mn, 0.04% AI, 0.015% Nb, 0.026% Ti) Examinations show that welded joints are free from defects. In the case of subsequent heat treatment of the welded joints, the addition of 0.096% Ti guarantees the absence of solid solution carbon in the heat-affected zone. The steels according to the invention have good continuous galvanization properties, in particular during an annealing cycle at 800 ° C. with a dew point temperature greater than -2 ° C.
Les aciers selon l'invention présentent donc une combinaison de propriétés (densité, une résistance mécanique, aptitude à la déformation, soudabilité, revêtabilité) particulièrement intéressante. Ces tôles d'aciers sont utilisées avec profit pour la fabrication de pièces de peau ou de structure dans le domaine automobile. The steels according to the invention thus have a combination of properties (density, mechanical strength, deformability, weldability, coating) particularly interesting. These steel sheets are used with advantage for the manufacture of skin parts or structure in the automotive field.

Claims

REVENDICATIONS
1 Tôle ferritique laminée à chaud en acier dont la composition comprend, les teneurs étant exprimées en poids :1 Ferritic sheet hot rolled of steel whose composition comprises, the contents being expressed by weight:
0,001< C <0,15%0.001 <C <0.15%
Mn ≤ 1%Mn ≤ 1%
Si ≤ 1 ,5%If ≤ 1, 5%
6% ≤AI < 10% 0,020% < Ti < 0,5%6% ≤ AI <10% 0.020% <Ti <0.5%
S < 0,050% P ≤ 0, 1% et, à titre optionnel, un ou plusieurs éléments choisis parmi :S <0.050% P ≤ 0, 1% and, optionally, one or more elements chosen from:
Cr < 1% Mo < 1%Cr <1% Mo <1%
Ni < 1%Ni <1%
Nb < 0,1 %Nb <0.1%
V < 0,2%,V <0.2%,
B ≤ 0,010% le reste de la composition étant constitué de fer et d'impuretés inévitables résultant de l'élaboration, la taille moyenne de grain de ferrite d|V mesurée sur une surface perpendiculaire à la direction transverse par rapport au laminage étant inférieure à 100 micromètresB ≤ 0.010% the remainder of the composition consisting of iron and unavoidable impurities resulting from the elaboration, the average size of ferrite grain d | V measured on a surface perpendicular to the direction transverse to the rolling being less than 100 micrometers
2 Tôle ferritique laminée à froid et recuite en acier de composition selon la revendication 1 , caractérisée en ce que sa structure est constituée de ferrite équiaxe dont la taille moyenne de grain dα est inférieure à 50 micromètres, et en ce que la fraction linéaire f de précipités K intergranulaires2 cold-rolled ferritic sheet annealed steel composition according to claim 1, characterized in that its structure consists of equiaxed ferrite whose average grain size α is less than 50 micrometers, and in that the linear fraction f intergranular K precipitates
est inférieure à 30%, ladite fraction linéaire f étant définie par :f , ∑di désignant la longueur totale des joints de grains comportant desis less than 30%, said linear fraction f being defined by: f Where Σdi is the total length of the grain boundaries with
(S) précipités K relativement à une surface (S) considérée, ∑Li désignant la(S) precipitated K relative to a surface (S) considered, ΣLi designating the
(5) longueur totale des joints de grains relativement à ladite surface (S) considérée(5) total length of grain boundaries relative to said surface (S) considered
3 Tôle en acier selon la revendication 1 ou 2, caractérisée en ce que sa composition comprend, les teneurs étant exprimées en poids3 steel sheet according to claim 1 or 2, characterized in that its composition comprises, the contents being expressed by weight
0,001 % ≤C < 0,010% Mn < 0,2%0.001% ≤C <0.010% Mn <0.2%
4 Tôle en acier selon la revendication 1 ou 2, caractérisée en ce que sa composition comprend, les teneurs étant exprimées en poids4 steel sheet according to claim 1 or 2, characterized in that its composition comprises, the contents being expressed by weight
0,010 % < C < 0,15% 0,2% < Mn ≤ 1%0.010% <C <0.15% 0.2% <Mn ≤ 1%
5 Tôle en acier selon l'une quelconque des revendications 1 à 4, caractérisée en ce que sa composition comprend, les teneurs étant exprimées en poids :Steel sheet according to any one of claims 1 to 4, characterized in that its composition comprises, the contents being expressed by weight:
7,5 % <AI ≤ 10%7.5% <AI ≤ 10%
6 Tôle en acier selon l'une quelconque des revendications 1 à 4, caractérisée en ce que sa composition comprend, les teneurs étant exprimées en poids :6 steel sheet according to any one of claims 1 to 4, characterized in that its composition comprises, the contents being expressed by weight:
7,5 % ≤AI < 8,5%7.5% ≤AI <8.5%
7 Tôle en acier selon l'une quelconque des revendications 1 à 6, caractérisée en ce que la teneur en carbone en solution solide est inférieure à 0,005% en poids 8 Tôle en acier selon l'une quelconque des revendications 1 à 7, caractérisée en ce que sa résistance Rm est supérieure ou égale à 400MPaSteel sheet according to one of Claims 1 to 6, characterized in that the carbon content in solid solution is less than 0.005% by weight 8 steel sheet according to any one of claims 1 to 7, characterized in that its resistance R m is greater than or equal to 400MPa
9 Tôle en acier selon la revendication 4, caractérisée en ce que sa résistance Rm est supérieure ou égale à 600MPa9 steel sheet according to claim 4, characterized in that its resistance R m is greater than or equal to 600MPa
10 Procédé de fabrication d'une tôle d'acier laminée à chaud selon lequel :A method of manufacturing a hot-rolled steel sheet according to which:
- On approvisionne un acier de composition selon l'une quelconque des revendications 1 à 6 - On coule ledit acier sous forme de demi-produit, puis- A steel composition is provided according to any one of claims 1 to 6 - said steel is cast as a semi-finished product, then
- On porte ledit demi-produit à une température supérieure ou égale à 11500C, puis- bringing said semi-finished product at a temperature greater than or equal to 1150 0 C, then
- On lamine à chaud ledit demi-produit pour obtenir une tôle, grâce à au moins deux étapes de laminage effectuées à des températures supérieures à 10500C, le taux de réduction de chacune desdites au moins deux étapes étant supérieur ou égal à 30%, le temps s'écoulant entre chacune desdites au moins deux étapes de laminage, et l'étape de laminage suivante, étant supérieur ou égal à 10 s, puisSaid half-product is hot rolled to obtain a sheet, by means of at least two rolling stages carried out at temperatures greater than 1050 ° C., the reduction ratio of each of the said at least two stages being greater than or equal to 30%; the time elapsing between each of the at least two rolling steps, and the next rolling step being greater than or equal to 10 s, and
- on achève le laminage à une température TFL supérieure ou égale à 900°C, puisthe rolling is completed at a temperature TFL greater than or equal to 900 ° C., and then
- on refroidit ladite tôle de telle sorte que l'intervalle de temps tp s'écoulant entre 850 et 7000C soit supérieur à 3 s, pour obtenir une précipitation de précipités K, puissaid sheet is cooled so that the time interval t p flowing between 850 and 700 ° C. is greater than 3 s, to obtain a precipitation of precipitates K, then
- on bobine ladite tôle à une température Tbob comprise entre 500 et 700°Csaid sheet is reeled at a temperature T b ob of between 500 and 700 ° C.
11 Procédé de fabrication d'une tôle laminée à chaud selon la revendication 10, caractérisé en ce que ladite coulée est effectuée directement sous forme de coulée de brames minces ou de bandes minces entre cylindres contra-rotatifs11 A process for manufacturing a hot rolled sheet according to claim 10, characterized in that said casting is carried out directly in the form of casting thin slabs or thin strips between contra-rotating cylinders
12 Procédé de fabrication d'une tôle en acier laminée à froid et recuite selon lequel : - On approvisionne une tôle d'acier laminée à chaud fabriquée selon la revendication 10 ou 11, puis12 Process for manufacturing a cold-rolled and annealed steel sheet according to which: - A hot-rolled steel sheet manufactured according to claim 10 or 11 is supplied and then
- On lamine à froid ladite tôle avec un taux de réduction compris entre 30 et 90%, de façon à obtenir une tôle laminée à froid, puis - On chauffe ladite tôle laminée à froid à une température T' avec une vitesse Vc supérieure à 3°C/s, puisSaid sheet is cold-rolled with a reduction ratio of between 30 and 90%, so as to obtain a cold-rolled sheet, and then said cold-rolled sheet is heated to a temperature T 'with a speed V c greater than 3 ° C / s, then
- On refroidit ladite tôle à une vitesse VR inférieure à 100°C/s- Cooling said sheet at a speed V R less than 100 ° C / s
- ladite température T1 et ladite vitesse VR étant choisies de façon à obtenir une recristallisation complète, une fraction linéaire f de précipités K intergranulaires inférieure à 30% et une teneur en carbone en solution solide inférieure à 0,005% en poidssaid temperature T 1 and said speed VR being chosen so as to obtain a complete recrystallization, a linear fraction f of intergranular K precipitates of less than 30% and a carbon content in solid solution of less than 0.005% by weight
13 Procédé de fabrication selon la revendication 12, caractérisé en ce qu'on chauffe ladite tôle laminée à froid à une température T comprise entre 750 et 9500C13 Manufacturing process according to claim 12, characterized in that said cold-rolled sheet is heated to a temperature T of between 750 and 950 ° C.
14 Procédé de fabrication selon la revendication 12, caractérisé en ce qu'on approvisionne une tôle de composition selon la revendication 4 et en ce qu'on chauffe ladite tôle laminée à froid à une température T' choisie de façon à éviter la dissolution de précipités K14 Manufacturing process according to claim 12, characterized in that supplies a sheet of composition according to claim 4 and in that said cold rolled sheet is heated to a temperature T 'chosen so as to avoid the dissolution of precipitates K
15 Procédé de fabrication selon la revendication 12, caractérisé en ce qu'on approvisionne une tôle de composition selon la revendication 4 et en ce qu'on chauffe ladite tôle laminée à froid à une température T' comprise entre 750 et 8000CManufacturing method according to claim 12, characterized in that supplies a composition sheet according to claim 4 and in that said cold rolled sheet is heated to a temperature T 'of between 750 and 800 0 C
16 Utilisation de tôles d'acier selon l'une quelconque des revendications 1 à 9, ou fabriquées selon l'une quelconque des revendications 10 à 15 pour la fabrication de pièces de peau ou de pièces structurales dans le domaine automobile 16 Use of steel sheets according to any one of claims 1 to 9, or manufactured according to any one of claims 10 to 15 for the manufacture of skin parts or structural parts in the automotive field
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Families Citing this family (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2406404B1 (en) * 2009-03-11 2017-08-23 Salzgitter Flachstahl GmbH Method for producing a hot rolled strip from ferritic steel by horizontal strip casting
JP5257239B2 (en) * 2009-05-22 2013-08-07 新日鐵住金株式会社 High strength low specific gravity steel plate excellent in ductility, workability and toughness, and method for producing the same
KR20140129150A (en) * 2012-02-20 2014-11-06 타타 스틸 네덜란드 테크날러지 베.뷔. High strength bake-hardenable low density steel and method for producing said steel
JP2015515547A (en) * 2012-04-11 2015-05-28 タタ、スティール、ネダーランド、テクノロジー、ベスローテン、フェンノートシャップＴａｔａ Ｓｔｅｅｌ Ｎｅｄｅｒｌａｎｄ Ｔｅｃｈｎｏｌｏｇｙ Ｂｖ High strength IF low density steel and method for producing the steel
WO2013178887A1 (en) * 2012-05-31 2013-12-05 Arcelormittal Investigación Desarrollo Sl Low-density hot- or cold-rolled steel, method for implementing same and use thereof
WO2014014120A1 (en) * 2012-07-20 2014-01-23 新日鐵住金株式会社 Steel material
US9315883B2 (en) 2012-09-14 2016-04-19 Tata Steel Nederland Technology Bv High strength and low density particle-reinforced steel with improved E-modulus and method for producing said steel
CN103691741A (en) * 2012-09-27 2014-04-02 日立金属株式会社 Manufacturing method of making fe-a1 alloy strip steel
CN103884624A (en) * 2012-12-21 2014-06-25 鞍钢股份有限公司 Crystal boundary density measuring method
EP2767601B1 (en) * 2013-02-14 2018-10-10 ThyssenKrupp Steel Europe AG Cold rolled steel flat product for deep drawing applications and method for its production
ES2736303T3 (en) * 2013-02-14 2019-12-27 Thyssenkrupp Steel Europe Ag Cold rolled steel flat product for deep drawing applications and manufacturing process
CR20170156A (en) 2014-10-20 2017-09-22 Arcelormittal METHOD OF PRODUCTION OF LEAF CONTAINING A SILICON STEEL SHEET OF NON-ORIENTED GRAIN, STEEL SHEET OBTAINED AND USE OF THIS.
WO2017125147A1 (en) * 2016-01-20 2017-07-27 Thyssenkrupp Steel Europe Ag Flat steel product and method for the production thereof
WO2017163098A1 (en) * 2016-03-25 2017-09-28 Arcelormittal Process for manufacturing cold-rolled and welded steel sheets, and sheets thus produced
CN105908089B (en) 2016-06-28 2019-11-22 宝山钢铁股份有限公司 A kind of hot-dip low density steel and its manufacturing method
CN106011652B (en) * 2016-06-28 2017-12-26 宝山钢铁股份有限公司 A kind of excellent cold rolling low-density steel plate of phosphorus characteristic and its manufacture method
RU2627079C1 (en) * 2016-11-17 2017-08-03 Федеральное Государственное Унитарное Предприятие "Центральный научно-исследовательский институт черной металлургии им. И.П. Бардина" (ФГУП "ЦНИИчермет им. И.П. Бардина") Method of manufacture of high-strengthen corrosive-resistant hot-rolled steel with low specific weight
CN106756478B (en) * 2016-12-07 2018-03-27 钢铁研究总院 A kind of economical seawater corrosion resistance low-density low-alloy steel and preparation method thereof
KR20190065671A (en) * 2017-12-04 2019-06-12 현대자동차주식회사 Ferric lightweight steel
CN108359897B (en) * 2018-03-19 2020-01-31 武汉钢铁有限公司 precipitation strengthening ferritic steels with yield strength of 1000MPa and production method thereof
CN111378908B (en) * 2020-03-18 2021-10-01 云南昆钢耐磨材料科技股份有限公司 Preparation method of alloy steel lining plate
CN112226701B (en) * 2020-09-11 2021-12-31 北京科技大学 High-aluminum-content fine-grain low-density full-high-temperature ferrite steel and preparation method thereof
CN112877606B (en) * 2021-01-12 2022-03-08 钢铁研究总院 Ultrahigh-strength full-austenite low-density steel and preparation method thereof
CN114480988B (en) * 2021-12-27 2023-01-06 北京科技大学 Multiphase composite high-strength high-toughness low-density steel and preparation method thereof
US12082533B2 (en) 2022-03-10 2024-09-10 Vermeer Manufacturing Company Wrap material guide pan for round baler

Family Cites Families (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1044801A (en) * 1963-01-30 1966-10-05 Yawata Iron & Steel Co Improvements in or relating to aluminum steels
JPH0723521B2 (en) * 1990-06-22 1995-03-15 川崎製鉄株式会社 Welded structural steel with excellent vibration damping characteristics
JPH056748A (en) 1991-06-21 1993-01-14 Mitsubishi Electric Corp Flat cathode-ray tube
CN1040343C (en) * 1993-04-26 1998-10-21 新日本制铁株式会社 Sheet steel excellent in flanging capability and process for producing the same
US5595706A (en) * 1994-12-29 1997-01-21 Philip Morris Incorporated Aluminum containing iron-base alloys useful as electrical resistance heating elements
DE19634524A1 (en) * 1996-08-27 1998-04-09 Krupp Ag Hoesch Krupp Lightweight steel and its use for vehicle parts and facade cladding
JP2001001053A (en) * 1999-04-22 2001-01-09 Aisin Seiki Co Ltd Roll-formed part and bumper for automobile
JP2001271148A (en) * 2000-03-27 2001-10-02 Nisshin Steel Co Ltd HIGH Al STEEL SHEET EXCELLENT IN HIGH TEMPERATURE OXIDATION RESISTANCE
AUPR048000A0 (en) * 2000-09-29 2000-10-26 Bhp Steel (Jla) Pty Limited A method of producing steel
JP4056748B2 (en) * 2002-01-21 2008-03-05 花王株式会社 How to determine the quality of fly ash
FR2836930B1 (en) * 2002-03-11 2005-02-25 Usinor HOT ROLLED STEEL WITH HIGH RESISTANCE AND LOW DENSITY
JP4235077B2 (en) 2003-06-05 2009-03-04 新日本製鐵株式会社 High strength low specific gravity steel plate for automobile and its manufacturing method
JP4430502B2 (en) 2004-02-24 2010-03-10 新日本製鐵株式会社 Method for producing low specific gravity steel sheet with excellent ductility
JP5062985B2 (en) * 2004-10-21 2012-10-31 新日鉄マテリアルズ株式会社 High Al content steel plate with excellent workability and method for producing the same
JP4324072B2 (en) 2004-10-21 2009-09-02 新日本製鐵株式会社 Lightweight high strength steel with excellent ductility and its manufacturing method
JP4299774B2 (en) * 2004-12-22 2009-07-22 新日本製鐵株式会社 High strength low specific gravity steel sheet with excellent ductility and fatigue characteristics and method for producing the same
US20070227634A1 (en) * 2005-03-16 2007-10-04 Mittal Steel Gandrange Forged or Stamped Average or Small Size Mechanical Part
ES2528427T3 (en) * 2005-08-05 2015-02-09 Jfe Steel Corporation High tensile steel sheet and procedure to produce it
JP4797807B2 (en) * 2006-05-30 2011-10-19 Ｊｆｅスチール株式会社 High-rigidity low-density steel plate and manufacturing method thereof

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2008145872A1 *

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CN101755057B (en) 2012-03-28
PL2155916T3 (en) 2011-05-31
DE602008003801D1 (en) 2011-01-13
EP2155916B2 (en) 2015-03-11
ES2356186T5 (en) 2015-06-19
ZA200907619B (en) 2010-05-26
US20100300585A1 (en) 2010-12-02
US9580766B2 (en) 2017-02-28
CA2687327A1 (en) 2008-12-04
US20170101694A1 (en) 2017-04-13
JP2014040668A (en) 2014-03-06
ES2356186T3 (en) 2011-04-05
CN101755057A (en) 2010-06-23
ATE490348T1 (en) 2010-12-15
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AR066569A1 (en) 2009-08-26
UA99827C2 (en) 2012-10-10
CA2687327C (en) 2012-06-26
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JP2010526939A (en) 2010-08-05
PL2155916T5 (en) 2016-06-30
MA31363B1 (en) 2010-05-03
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US9765415B2 (en) 2017-09-19
JP5552045B2 (en) 2014-07-16

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