WO2023144019A1 - Bande d'acier à haute résistance laminée à chaud - Google Patents

Bande d'acier à haute résistance laminée à chaud Download PDF

Info

Publication number
WO2023144019A1
WO2023144019A1 PCT/EP2023/051306 EP2023051306W WO2023144019A1 WO 2023144019 A1 WO2023144019 A1 WO 2023144019A1 EP 2023051306 W EP2023051306 W EP 2023051306W WO 2023144019 A1 WO2023144019 A1 WO 2023144019A1
Authority
WO
WIPO (PCT)
Prior art keywords
steel strip
hot
rolled
strength
strength steel
Prior art date
Application number
PCT/EP2023/051306
Other languages
English (en)
Inventor
Rolf Arjan RIJKENBERG
Maxim Peter AARNTS
Anton Romulus CHEZAN
Original Assignee
Tata Steel Ijmuiden B.V.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tata Steel Ijmuiden B.V. filed Critical Tata Steel Ijmuiden B.V.
Publication of WO2023144019A1 publication Critical patent/WO2023144019A1/fr

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • 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
    • C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • 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
    • C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
    • 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
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • 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
    • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium 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
    • C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with 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
    • C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
    • 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

Definitions

  • the invention relates to a hot-rolled high-strength steel strip and which is in particular suitable for use in automotive components.
  • the invention also relates to a method of manufacturing such a hot-rolled high-strength steel strip.
  • the invention relates to an automotive part incorporating the hot-rolled high-strength steel strip.
  • HR steel strip hot-rolled steel strip
  • C&S chassis and suspension
  • Other areas include frame rails of trucks, bumper beams or battery boxes for electrical vehicles.
  • the typical thickness of HR steels used for these applications is less than 4.5 mm.
  • Thicker gauge HR steel strip such as up to 12 mm can be used in engineering applications such as crane booms or in transport applications for frames of heavy trucks. From the weight reduction perspective it is imperative that higher strength steels should be employed for the above applications in order to be able to reduce the gauge of the steel strip. Therefore, ultra-high strength steels with ultimate tensile strength (Rm) of typically over 950 MPa would be useful for this purpose.
  • the steel strip should also have good formability for making the component via e.g. cold-forming because this is an energy efficient manufacturing route in comparison with hot-forming. Furthermore, good impact and fracture toughness or energy absorption capacity is also required for applications like bumper beams, battery housings, crane booms or frame rails. For assembling the components, also a good weldability is required. However, as the tensile strength of the steels increases the formability parameters decrease. Formability is a generic term for steel sheets which is viewed as a combination of material behaviour during several mechanical operations such as stretching, bending, drawing and flanging. Depending on the component geometry any or a combination of two or more attributes of the material is of importance during sheet metal forming.
  • the common approach is to apply high-strength steel and to reduce the thickness of the steel strip used to save weight.
  • This may lead to a loss in stiffness, which for some applications in automotive parts is undesirable.
  • the intrinsic loss in stiffness by reducing the thickness of the steel strip used to manufacture automotive components can be regained by optimisation of the component geometry, e.g. creating deeper flanges or flanges with an increased degree of stretching or bending.
  • the high-strength steel strip requires an excellent formability in terms of tensile elongation and hole expansion capacity.
  • Single-phase precipitation-strengthened ferritic high-strength steels that break free from the conventional constraints between global formability (e.g. tensile elongation) and local formability (e.g. hole-expansion capacity or HEC) with both formability modes at a high level, may have low fracture toughness values and increased edge crack sensitivity in certain conditions, e.g., under compression, and are prone to have increased susceptibility to unstable brittle fracture behaviour and delamination during shearing, which impairs sheared- edge fatigue.
  • global formability e.g. tensile elongation
  • local formability e.g. hole-expansion capacity or HEC
  • Patent document EP1616970-A1 discloses a method for manufacturing a high-strength hot-rolled steel sheet comprising the steps of: reheating a steel slab consisting of, in wt.%, 0.04 to 0.15 % C, 1.5 % or less Si, 0.5 to 1.6 % Mn, 0.04 % or less P, 0.005 % or less S, 0.04 % or less Al, 0.03 to 0.15 % Ti, 0.03 to 0.5 % Mo, by mass, and balance of Fe and inevitable impurities in a temperature range from 1150 to 1300 °C; hot rolling the reheated steel slab at a finishing temperature of the Ar3 transformation temperature or above into a hot rolled steel sheet; primarily cooling the hot rolled steel sheet in a temperature range from 700 to 850°C at an average cooling rate of 20°C/s or more; holding the primarily cooled steel sheet at a temperature of 680°C or above for more than 1 sec; and secondarily cooling the steel sheet at a temperature of
  • the hot-rolled steel sheet is primarily cooled to a temperature range not only from 700 to 850°C but also from (SRT/3 + 300) to (SRT/8 + 700)°C, where the SRT designates the reheating temperature of the steel slab.
  • SRT designates the reheating temperature of the steel slab.
  • the processing conditions are such that a microstructure is obtained which consists of ferrite containing precipitates, second phase of bainite and/or martensite, and other phase, wherein the percentage of the ferrite containing precipitates is 40 to 95%, and the percentage of the other phase being 5% or less.
  • Patent document EP1338665-A1 discloses a method for manufacturing a high strength hot rolled steel sheet, comprising the steps of: producing a steel slab which consists essentially of, in wt.%, 0.06 % or less C, 0.5 % or less Si, 0.5 to 2.0 % Mn, 0.06 % or less P, 0.005 % or less S, 0.1 % or less Al, 0.006 % or less N, 0.05 to 0.6 % Mo, 0.02 to 0.10 % Ti, and the balance being Fe, and satisfies the equation of 0.8 ⁇ (C/12)/[(Ti/48) + (Mo/96)] ⁇ 1.3; producing a hot rolled steel sheet by hot rolling said steel slab at a temperature of Ar3 transformation point or higher; and coiling said hot rolled steel sheet at a temperature of 550 to 700°C.
  • the processing conditions are such that a microstructure is obtained that consists essentially of a matrix of ferrite structure single phase and fine precipitates which are composite carbides containing Ti and Mo, with a grain size of smaller than 10 nm dispersed in said matrix wherein said fine precipitates are dispersed at a number per unit volume of 5 x 10 4 / ⁇ m 3 or higher.
  • the term "about" when used to describe a compositional range or amount of an alloying addition means that the actual amount of the alloying addition may vary from the nominal intended amount due to factors such as standard processing variations as understood by those skilled in the art.
  • up to 0.03% Cr may include a steel strip composition having no Cr.
  • a hot-rolled high-strength steel strip having a composition consisting of, in wt.%, 0.02 - 0.13 wt.% C, 1.20 - 3.50 wt.% Mn,
  • 0.04 - 0.25 wt.% Ti up to 0.010 wt.% N (100 ppm), preferably up to 0.0065 wt.% N (65 ppm), up to 0.02 wt.% P, preferably up to 0.015 wt.% P, up to 0.01 wt.% S, preferably up to 0.0025 wt.% S (25 ppm), up to 0.0050 wt.% B (50 ppm), preferably up to 0.0030 wt.% B (30 ppm), optionally one or more elements selected from the group consisting of:
  • the steel strip has a microstructure of at least 95 vol.% ferrite and at most 5 vol.% martensite, and preferably at least 0.2 vol.% martensite; has a MisOrientation Distribution (MOD) index of at least 0.65 at %-th
  • the hot-rolled steel strip having these narrow alloy compositional ranges in combination with the microstructure provides for an improved balance of high strength (Rm), total elongation (A50) and hole expansion ratio. It is also an important finding of this invention that the microstructure of the steel strip results in a reduced edge crack sensitivity in a forming operation.
  • a reduced crack sensitivity, in particular reduced edge-crack sensitivity can be objectively expressed in an average total crack length (ATCL) following the measuring method as herein described.
  • ATCL average total crack length
  • the steel strip according to this invention has an ATCL of less than 45 mm, and in the best examples of less than 40 mm.
  • the steel strip it has a yield strength (Rp) is at least 800 MPa, and preferably of at least 850 MPa. In an embodiment of the steel strip it has a yield strength (Rp) of maximum 960 MPa, and preferably of maximum 950 MPa.
  • the steel strip has an ultimate tensile strength (Rm) of at least 950 MPa. In an embodiment of the steel strip it has an ultimate tensile strength of at least 960 MPa and preferably of at least 980 MPa.
  • the steel strip has a total elongation (A50) of at least 10%, and preferably of at least 14%.
  • the required microstructure for this steel strip is achieved by the narrow compositional ranges and by careful control of the manufacturing process, the accelerated cooling of the steel strip on the run-out table (ROT) and the narrow operating window for the coiling temperature (CT) in particular.
  • ROT run-out table
  • CT coiling temperature
  • the microstructure of the steel strip according to this invention consists of at least 95 vol.% ferrite, and which is precipitation-strengthened with carbide precipitates of titanium and molybdenum, optionally with vanadium and/or niobium; and at most 5 vol.% martensite, balance is inevitable amounts of inclusions, and the sum adding up to 100 vol.%.
  • the microstructure has at least 98 vol.% ferrite, and more preferably at least 99 vol.%.
  • the presence of some martensite is favourable to blunt any crack tip and reduces crack propagation.
  • the martensite may contain some traces of retained austenite, but retained austenite is preferably not present.
  • the microstructure of the steel strip has preferably at least 0.2 vol.% martensite, and more preferably at least 0.3 vol.%. In a preferred embodiment the steel strip has at most 3 vol.% martensite, and more preferably at most 2 vol.%.
  • the texture of the overall microstructure of the steel strip is further characterised by a sufficiently high MisOrientation Distribustion (MOD) index of at least 0.65, preferably of at least 0.80, and more preferably of at least 0.83, and in the best examples of at least 0.90.
  • the MOD index is to be measured at quarter-thickness of the steel strip.
  • the texture of the overall microstructure of the steel strip is further characterized by an area fraction of at most 55%, and more preferably of at most 52%, with a Kernel Average Misorientation (KAM) of 0-1, and an area fraction of at least 45%, and more preferably of at least 48%, with a Kernel Average Misorientation (KAM) of 1-5.
  • KAM Kernel Average Misorientation
  • the overall microstructure of the steel strip is further characterised by a (5° to 65°) grain boundary length ( ⁇ GB) of at least 1400 per mm/mm 2 or 1/mm, and preferably of at least 1500 1/mm.
  • ⁇ GB grain boundary length
  • a higher ⁇ GB indicates a higher degree of grain refinement resulting in a desired reduced crack sensitivity and suppression or arrest of the crack propagation resulting in a favourable shorter ATCL, for instance when under compression.
  • Carbon is present in an amount between 0.02 and 0.13 wt.%.
  • a suitable minimum C content is 0.04 wt.%, and in a preferred embodiment at least 0.070 wt.%.
  • the C content is at most 0.12 wt.% and is beneficial to suppress the effect of cooling rate dependence on the homogeneity of the final microstructure and to promote high hole-expansion capacity.
  • C is an essential element to achieve precipitation strengthening in combination with carbide-forming micro- alloying elements like titanium, niobium (if added) or vanadium (if added), and to scavenge C to suppress cementite formation in the final microstructure.
  • By optimizing other alloying elements, including Ti, Nb, and/or V it is possible to obtain an almost uniform ferritic or bainitic-ferritic microstructure with substantially no cementite.
  • the steel strip has Mn in a range of 1.20 wt.% to 3.50 wt.% to achieve sufficient hardenability and grain refinement.
  • the Mn content is in a range of 1.40 wt.% to 2.40 wt.% for an improved balance in strength, corrosion resistance, fracture toughness and edge crack sensitivity.
  • the Mn content is at least 1.50 wt.% to obtain sufficient grain refinement improving the fracture toughness and reducing crack susceptibility.
  • the Mn content is maximum 2.20 wt.%, and more preferably maximum 2.0 wt.%. A too high Mn content may lead to segregation during casting which adversely affects the required balance in properties.
  • Silicon is present in an amount of 0.10 to 1.0 wt.% to improve the strength of the steel by substitutional solid solution strengthening of the iron lattice. Furthermore, Si is beneficial to suppress carbide precipitation (cementite and other carbides). However, when using higher amounts of Si the weldability and coatability of the steel deteriorates, hence the amount of Si is preferably at most 0.95 wt.%, and in a preferred embodiment at most 0.70 wt.% and more preferably at most 0.60 wt.%. Aluminium behaves comparable to Si in the steel according to the invention. It slows down the carbide precipitation kinetics and suppresses the formation of cementite.
  • Al is less than 0.02 wt.%, the effects of suppression of carbide formation are negligible. Values of aluminium lower than 0.02 wt.% are deemed to be residuals from the deoxidation step during steelmaking, and therefore a minimum value of about 0.02 wt.% is preferred.
  • Al is above 0.70 wt.% there can be excessive oxide formation during thermomechanical processing (slab reheating, hot rolling, coiling etc.) of the steel.
  • Al increases the ferrite to austenite transformation temperature demanding the need for hot rolling the steel at higher temperatures to finish hot-rolling in the austenitic phase since at lower temperatures intercritical ferrite appears. Higher amounts of oxidation can occur at higher temperatures.
  • Al in the present invention is present in an amount of 0.02 to 0.70 wt.%, preferably 0.02 to 0.60 wt.% and more preferably in the range of 0.030-0.50 wt.%.
  • Titanium is another essential alloying element and is present in an amount between 0.04 and 0.25 wt.% as it provides hardenability and acts as a carbide forming element suppressing the formation of cementite while providing precipitation strengthening via the formation of small Ti-based carbides.
  • Ti also combines with N, S and C to form nitrides, and carbo-sulphides, depending on the specific chemical composition of the steel. Therefore, at least 0.04 wt.% Ti is present to bind substantially all the N and S in the steel and to have sufficient excess Ti to combine with C in the steel.
  • Ti When more than 0.25 wt.% Ti is present, coarse Ti nitrides, carbo-nitrides, and carbides may form which are difficult to dissolve during reheating of the slab prior to hot rolling. Furthermore, these coarse Ti nitrides, carbo-nitrides, and carbides lead to a deterioration of the hole expansion capacity of the steel.
  • 0.07 to 0.22 wt.% Ti is present. In an embodiment the Ti content does not exceed 0.20 wt.%, preferably it does not exceed 0.15 wt.%, and more preferably it does not exceed 0.13 wt.%.
  • the steel strip has Mo as a purposive alloying element present in a range of about 0.05 wt.% to 1.0 wt.% to achieve hardenability.
  • Mo content is at least about 0.10 wt.%, and preferably at least about 0.20 wt.%, and more preferably at least 0.25 wt.%, and most preferably at least 0.30 wt.%.
  • Mo-content does not exceed about 0.80 wt.%, and preferably does not exceed about 0.55 wt.%, and more preferably does not exceed 0.40 wt.%.
  • the presence of Mo may improve also the weldability of the steel strip.
  • Nitrogen, sulphur and phosphorus are residual elements present in the steel as a result of steel making and refining process. Their amounts are limited to up to 0.01 wt.% S, up to 0.02 wt.% P, and up to 0.010 wt.% N. Amounts higher than these are detrimental for mechanical properties, formability, toughness, and weldability.
  • P is present only up to 0.015 wt.%.
  • S is present only up to 0.005 wt.% and more preferably only up to 0.0025 wt.%.
  • N forms titanium nitrides with Ti which act as dispersoids for austenite grain size control during reheating.
  • the N content is up to 0.0065 wt.% (65 ppm).
  • a suitable minimum N content is 0.0010 wt.% (10 ppm).
  • Boron is not required to obtain the desired balance of properties of the steel strip, but can be present up to 0.005 wt.%, thus up to 50 ppm, and preferably up to 0.0030 wt.% (30 ppm).
  • B is very effective to enhance the hardenability of the steel, which means that a low carbon content and/or lower cooling rates can be used on the run-out table while no or only little pro-eutectic ferrite is formed.
  • B is also an alloying element that is very suitable to increase the yield strength.
  • Cr can be added to the steel strip in an amount of up to about 0.70 wt.%, and preferably up to 0.25 wt.%, and increases the hardenability of the steel.
  • the steel strip has Cr as a tolerable impurity element. It practice this means it can be present up to 0.10%, preferably up to 0.050%, and more preferably up to 0.03%, as it can impair corrosion performance of the uncoated steel strip substrate.
  • Copper when present up to 1.5 wt.%, increases the strength of the steel by both solid solution strengthening as well as precipitation hardening through copper precipitates.
  • the Cu content does not exceed 0.6 wt.%.
  • the Cu is not added as a purposive alloying element and can be present up to 0.10 wt.%, and more preferably up to 0.05 wt.%.
  • Nickel up to about 0.50 wt.%, and preferably up to 0.30 wt.%, increases the impact toughness and counters any hot shortness that can occur during hot working of the steel strip due to the presence of copper.
  • the Ni is not added as a purposive alloying element and can be present up to 0.3 wt.%, preferably up to 0.10 wt.%, and more preferably up to 0.050 wt.%.
  • Vanadium can be present in the steel up to an amount of about 0.30 wt.%, and preferably up to about 0.20 wt.%, and more preferably up to 0.17 wt.%.
  • V is a relatively costly alloying element that is mostly used to replace Ti for its precipitation strengthening effect and to avoid cementite formation by forming vanadium carbides.
  • V is purposively added in an amount of at least 0.05 wt.%, and more preferably of at least 0.08 wt.%.
  • Ti and V is favoured as Ti offers a catalytic effect for V precipitation, making V precipitation more effective.
  • Niobium can be present in the steel up to 0.10 wt.%.
  • Nb improves the strength of the steel partly by precipitation hardening but foremost by grain refinement. However, for high amounts of Nb these effects are saturated. Therefore, preferably at most 0.08 wt.% Nb is present, and more preferably at most 0.060 wt.%
  • Nb is a rather expensive alloying element
  • Nb is not purposively added and is present as an impurity element and does not exceed 0.03 wt.%, and preferably it does not exceed 0.02 wt.%, and more preferably it does not exceed 0.0050 wt.%.
  • Nb is an inevitable impurity resulting from the ironmaking and steelmaking process.
  • Nb has a high tendency to segregate and to form coarse NbC particles due to centre-line segregation, thus the avoidance of the use of Nb results in an improved hole-expansion capacity and increased sheared-edge quality.
  • the amount of and carbide-forming elements Ti, Nb, V, and Mo represented in wt.% satisfy the equation of: with Ti_sol defined as the amount of free Ti in solution and expressed as: with the amount of Ti and N expressed in wt.%.
  • the lower limit of this equation is 0.75, more preferably 0.80.
  • the upper limit is preferably 1.8, and more preferably 1.5, to further suppress the presence of cementite and/or to control the amount of martensite.
  • the formula is in a range of 0.9 to 1.1.
  • the steel strip has a composition consisting of: 0.02 to 0.13 wt.% C, 1.20 to 2.0 wt.% Mn, 0.10 to 0.60 wt.% Si, 0.01 to 0.70 wt.% Al, 0.04 to 0.25 wt.% Ti, 0.05 to 0.80 wt.% Mo, up to 0.10% Cr, preferably up to 0.050% Cr, up to 0.010 wt.% N, up to 0.02 wt.% P, preferably up to 0.015 wt.% P, up to 0.01 wt.% S, preferably up to 0.0025 wt.% S, up to 0.0050 wt.% B, optionally one or more elements selected from the group consisting of: (up to 0.10% Cu, up to 0.10% Ni, up to 0.30% V, up to 0.10 wt.% Nb, preferably up to 0.03% Nb), and balance Fe and inevitable impurities resulting from the ironmaking and steelmaking process, and with
  • the 0.2% offset proof strength or yield strength (Rp), ultimate tensile strength (Rm), uniform elongation (Ag) and tensile elongation (A50) were determined from quasistatic (strain rate 3 x 10' 4 s' 1 ) tensile tests at room temperature with A50 specimen geometry with tensile testing parallel to the rolling direction according to EN 10002-1/150 6892-1.
  • the geometry of the tensile specimens consisted in 50 mm gauge length in the rolling direction, 12.5 mm in width and a thickness depending on the final gauge.
  • the strength of the steel at 0.2% offset strain is measured as the yield strength (Rp or YS).
  • the ratio of yield strength to ultimate tensile strength (Rp/Rm) is expressed as the yield ratio.
  • the average total crack length is used to assess the susceptibility of crack formation in situations similar to industrial applications.
  • the ATCL parameter is determined in a common laboratory cylindrical deep drawing tests, using a punch, a draw die, and a blank holder.
  • the punch has a 50 mm diameter with a punch radius of 7 mm.
  • the die has an inner diameter of 62 mm and a radius of 8 mm. This set up is shown schematically in Fig. IB.
  • the inner diameter is large enough to allow free movement of the edge of the formed cup.
  • the clearance i.e., the distance between the punch wall and die wall is 6 mm.
  • the blank holder force is set at 50 kN.
  • the blank is a square, measuring 90 x 90 mm.
  • the four corners of the square are 10 mm cut in the direction of the two diagonals as shown in Figure 1A.
  • four regions at the edge of the blank are plastically deformed due to high local compressive stresses during drawing. This results in local wrinkling of the edge.
  • the four compressed regions are subjected to reverse loading due to spring back as these regions of the formed cylindrical cup start to lose contact with the blank holder. This reverse loading due to spring back may lead to the nucleation and growth of cracks in the four compressed and wrinkled regions of the drawn cup (see for example Fig. IE).
  • Cracks may either be through the full thickness of the steel strip and visible at both sides, i.e., inner and outside, of the drawn cup or only visible at one of both sides of the cup.
  • the length of all visible cracks on the inside and outside of the four compressed edges (as illustrated in Fig. ID) of the deep-drawn cup is measured using a magnifying glass of lOx equipped with a scale grid.
  • the sum of the length of all observable cracks on the inside and outside of the cup wall is averaged over three of four drawn cups and reported as the average total crack length (ATCL) and expressed in mm.
  • EBSD Electron Back Scatter Diffraction
  • the Scanning Electron Microscope (SEM) used for the EBSD measurements is a Zeiss Ultra 55 machine equipped with a Field Emission Gun (FEG-SEM) and an EDAX PEGASUS XM 4 HIKARI EBSD system.
  • EBSD scans were collected on the RD-ND plane of the sheets at quarter- thickness. The samples were placed under a 70° angle in the SEM. The acceleration voltage was 15 kV with the high current option switched on. A 120 ⁇ m aperture was used and the typically working distance was 17 mm during scanning. To compensate for the high tilt angle of the sample, the dynamic focus correction was used during scanning.
  • the EBSD scans were captured using the TexSEM Laboratories (TSL) software: "Orientation Imaging Microscopy (OIM) Data Collection version 7.2". Typically, the following data collection settings were used: Hikari camera at 5 x 5 binning combined with background subtraction (standard mode). The scan area was in all cases located at a position of % the sample thickness and care was taken to avoid as much as possible to include non-metallic inclusions in the scan area. The EBSD scan size was in all cases 100 x 100 ⁇ m, with a step size of 0.1 ⁇ m, and a scan rate of approximately 100 frames per second. Fe(a) and Fe(y) was used to index the Kikuchi patterns.
  • TSL TexSEM Laboratories
  • OIM Orientation Imaging Microscopy
  • the Hough settings used during data collections were: Binned pattern size of circa 96; theta set size of 1; rho fraction of circa 90; maximum peak count of 10; minimum peak count of 5; Hough type set to classic; Hough resolution set to low; butterfly convolution mask of 9 x 9; peak symmetry of 0.5; minimum peak magnitude of 10; maximum peak distance of 20.
  • the EBSD scans were evaluated with TSL OIM Analysis software version "8.0 x64 [12-14- 16]". Typically, the data sets were 90° rotated over the RD axis to get the scans in the proper orientation with respect to the measurement orientation.
  • a standard grain dilation clean-up was performed (Grain Tolerance Angle (GTA) of 5°, a minimum grain size of 5 pixels, criterion used that a grain must contain multiple rows for a single dilation iteration clean-up).
  • GTA Gram Tolerance Angle
  • a pseudo-symmetry clean-up (GTA 5, axis ang 30°@lll) was applied.
  • the EBSD Image Quality (IQ) maps were used to determine the amount of martensite. Area with a low IQ were identified as MS areas. For the given experimental conditions, typically the low IQ threshold was ⁇ 0.4 of the peak-maximum position in the IQ histogram. The low IQ threshold was however manually checked for every scan to prevent including grain boundaries from granular bainite or upper bainitic areas in the martensite area fraction.
  • Kernel Average Misorientation maps the fifth nearest neighbour was used with a maximum misorientation of 5° (all points in kernel were used for KAM calculation).
  • the Kernel Average Misorientation is regarded as a signature for the type of ferrite since the Kernel Average Misorientation is a measure for the internal dislocation density. Areas with a relatively low internal dislocation density will predominantly correspond with areas that have a KAM value between 0 and 1°. Areas with a relatively high internal dislocation density will predominantly correspond with areas that have KAM value between 1- 5° .
  • ⁇ GB total grain boundary length of grain boundaries (in mm) with misorientation angles of 5° to 15° ( ⁇ GB5-15) and 15° to 65° ( ⁇ GB15-65) has been measured.
  • the value of ⁇ GB is expressed in mm' 1 and is a measure for the density of high-angle grain boundaries. High-angle grain boundaries are effective to arrest crack propagation. Hence, an increased value for ⁇ GB will be beneficial for increased fracture toughness and reduced crack susceptibility.
  • a method of manufacturing a steel strip as herein described and claimed comprising the steps of, in that order, casting a slab, followed by the step of reheating the solidified slab to a temperature between 1050°C and 1260°C, preferably for a time of 30 minutes or more, and more preferably of 60 minutes or more, and hot rolling said slab, or casting a slab or strip followed by the step of hot rolling said slab or strip; hot rolling the steel slab or strip and finishing said hot rolling at a finish rolling temperature between 820°C and 940°C, preferably between 850°C and 940°C, and most preferably between 850°C and 920°C, and above the Ar3 temperature of the steel.
  • the finish hot rolling temperature (FRT) is above the Ar3 temperature of the steel, where Ar3 is the temperature at which transformation of austenite to ferrite starts during cooling.
  • the Ar3 temperature can be calculated according to the following equation:
  • Ar3 910°C - 203 x [C] 1/2 + 44.7 x [Si] - 30 x [Mn] +31.5 x [Mo] ; accelerated cooling the hot rolled steel strip with a run-out table cooling rate between 20 to 250°C/s, and preferably between 40 to 200°C/s, to a temperature on the run-out-table between 560°C and 620°C; coiling the hot-rolled and cooled strip at a temperature between 550°C and 600°C, and preferably between 550°C and 595°C, and more preferably between 550°C and 590°C; allowing the coiled hot-rolled steel strip to further cool to ambient temperature; and pickling the hot-rolled steel strip, optionally providing the hot-rolled steel strip with a metallic coating layer, preferably selected from the group comprising: a Zn-layer, Zn-based alloy layer, an Al-based alloy layer, to provide improved corrosion resistance in service.
  • the metallic coating layer is preferably applied by means heat
  • the method of manufacturing herein described and claimed results in the desired microstructure providing for the aimed improved balance of formability, mechanical properties and fracture characterstics.
  • the invention is also embodied in a steel strip manufactured by the method described herein and claimed having said microstructure and improved balance of formability, mechanical properties and fracture characteristics.
  • the invention is not limited by the casting method.
  • the steel can be cast as a conventional thick-slab having a cast thickness of between 150 mm and 350 mm, and typically of 225 mm to 250 mm, as well as a thin-slab having a cast thickness of between 50 mm and 150 mm in direct strip plant.
  • Schematic examples of a process involving a conventional hot strip mill and of a thin slab casting/direct rolling mill are shown in figure 2A and 2B respectively.
  • reheating of the slab is necessary to reheat the slab from ambient temperatures (usually the think cast slabs have cooled down from the casting temperature to ambient temperatures in a slab yard) and to homogenise the slab with respect to composition, and therefore the reheating temperature should be above about 1050°C also to dissolve any precipitates when microalloying elements are present and to bring the slab to such a temperature that the final hot rolling in the finishing mill can still be performed at FRT>Ar3. Often this requires a (slab) reheating temperature of between 1050°C up to about 1260°C.
  • the cast slab is subjected to a homogenisation treatment in a homogenising furnace immediately after casting the thin slab wherein the homogenisation temperature should be above about 1050°C, and is typically about 1100 to 1160 °C. This would also prevent any precipitates from forming when microalloying elements, if any, are present and also bring the thin slab to such a temperature that the final hot rolling in the finishing mill can still be performed at FRT>Ar3.
  • the reheating or the homogenisation time for the thin slab casting route is preferably 30 minutes or more.
  • the hot rolling of the steel must be carried out in the austenitic phase to control the final microstructure.
  • the FRT should be kept above the Ar3 temperature.
  • the FRT is above (Ar3 + 30°C), e.g. typically above 850°C, to avoid hot rolling locally below Ar3 at colder edges or the tail of the strip.
  • the FRT should not be too high in the austenite region as a lower FRT will promote more austenite deformation and hence contribute to increased grain refinement and increased ⁇ GB.
  • a FRT of above 950°C will result in increased edge crack sensitivity.
  • a not too high FRT will also promote textures in the final microstructures that are beneficial for toughness (e.g.
  • FRT should not exceed about 940°C, preferably it does not exceed about 920°C, and more preferably it does not exceed about 910°C.
  • ROT run-out table
  • the cooling rate should be high enough to avoid austenite-to-ferrite phase transformation at elevated temperatures and to preferably promote austenite-to-ferrite phase transformation at relatively low temperatures of about 560 to 630°C on the run-out-table.
  • Increased cooling rate will promote grain refinement, increased ⁇ GB and hence increased fracture toughness and reduced crack susceptibility.
  • Increased cooling rate will also suppress texture randomisation and hence suppress the loss in intensity of those textures developed from deformed austenite that promote toughness (e.g., ⁇ 332 ⁇ 113>).
  • ROT-CR critical run-out table cooling rate
  • ROT-CR run-out table cooling rate
  • the hot-rolled steel strip is coiled at a temperature between 550°C and 600°C, and preferably between 550°C and 600°C, and more preferably between about 560°C and 600°C.
  • the hot-rolled strip is coiled at a temperature not exceeding 595°C, and more preferably not exceeding 590°C.
  • the coiling temperature of the steel strip is a key process parameter to arrive at the required microstructure of the steel strip providing for the improved balance in mechanical properties as herein described.
  • patent document EP1616970-A1 discloses that after holding the steel strip longer than 1 sec at a temperature of 680°C or above, it is necessary to apply secondary cooling to a coiling temperature of 550°C or below, preferably 450°C or below, and more preferably 350°C or below at an average cooling rate of 30°C/s or more, preferably 50°C/s or more, and coiling in order to form the secondary phase of bainite and/or martensite and to suppress the formation of other phase at 5 vol.% or less.
  • the coiling temperature is considerably higher with values between 550°C and 600°C, and preferably between 550°C and 595°C, and more preferably between 550°C and 590°C, in order to allow the austenite-to- ferrite phase transformation to continue at relatively low temperatures to promote fine- grained ferrite, which is precipitation strengthened with carbide precipitates comprising Ti and Mo, and optionally Nb and/or V.
  • the grain refinement and increased ⁇ GB provides for improved fracture toughness and reduced (edge-) crack susceptibility. Coiling below 550°C will lead to insufficient ferrite formation and loss in precipitation. Furthermore, it may lead to a too high martensite fraction.
  • patent document EP1338665-A1 discloses a coiling temperature in the range of 550 to 700°C, the steels produced having a tensile strength of at least 950 MPa and a hole- expansion capacity of at least 40%, were all produced with coiling temperatures exceeding 600°C.
  • the finish rolling temperatures for all these steels were in the range of 880 to 930°C.
  • too high coiling temperatures leads amongst others to increased crack susceptibility, in particular edge-crack susceptibility, and also reduced fracture toughness.
  • the oxides (scale) on the hot- rolled steel strips are removed either by pickling in an acid solution (e.g.
  • HCI HCI at warm temperatures (80-120°C) or by a combination of pickling and mechanical brushing of the strip surface. This step is necessary for rendering the steel strip surface suitable for direct use as uncoated hot-rolled steel or making it amenable to the coating process, when optionally needed for corrosion resistance.
  • the thickness of the hot-rolled steel strip is in a range of about 1.5 to 8 mm, and more preferably of about 1.8 to 6 mm, and most preferably of about 1.8 to 4 mm.
  • the hot-rolled steel strip product can be a bare product or uncoated product or it can be provided on one or both of its main surfaces with a thin metallic coating layer, typically up to about 100 g/m 2 per side of the steel strip, and preferably up to about 50 g/m 2 per side.
  • the metallic coating is preferably selected from the group comprising an aluminium alloy coating (e.g., an Al-Si alloy, or Al-Zn alloy), a zinc coating, and a zinc alloy coating (e.g., a Zn-AI alloy, Zn-Mg alloy, Zn-Fe alloy, Zn-AI-Mg alloy, or Zn-Mg-AI alloy).
  • the composition of the zinc or zinc alloy coating layer is not limited. Although the coating layer can be applied in various ways, hot-dip galvanising is preferred using a standard Gl coating bath.
  • the Zn based coating layer may comprise a Zn alloy containing Al as an alloying element.
  • a preferred zinc bath composition contains about 0.10-0.35 wt.% Al, the remainder being zinc and unavoidable impurities.
  • An example comprises a zinc alloy coating according to patent document W02008/102009-A1 and incorporated herein by reference, in particular a zinc alloy coating layer consisting of 0.3 to 4.0 wt.% Mg and 0.05% to 6.0 wt.% Al, preferably 0.1 to 5.0 % Al, and optionally at most 0.2 wt.% of one or more additional elements along with unavoidable impurities and the remainder being zinc.
  • a preferred Zn bath comprising Mg and Al as main alloying elements has the composition: 0.5 to 3.8 wt.% Al, 0.5 to 3.0 wt.% Mg, optionally at most 0.2 wt.% of one or more additional elements; the balance being zinc and unavoidable impurities.
  • An additional element typically added in a small amount of less than 0.2 wt.% could be selected from the group comprising Pb, Sb, Ti, Ca, Mn, Sn, La, Ce, Cr, Ni, Zr, and Bi. Pb, Sn, Bi, and Sb are usually added to form spangles.
  • the total amount of additional elements in the zinc alloy is at most 0.2 wt.%, and more preferably at most 0.1 wt.%. These small amounts of an additional element do not alter the properties of the coating nor the bath to any significant extent for the usual applications.
  • each is present in an amount up to 0.02 wt.%, preferably each is present in an amount up to 0.01 wt.%. Additional elements are usually only added to prevent dross forming in the bath with molten zinc alloy for the hot-dip galvanising, or to form spangles in the coating layer.
  • the metallic coating comprises a (commercially pure) aluminium layer or an aluminium alloy layer.
  • a typical metal bath for hot-dip coating such an aluminium layer comprises aluminium alloyed with silicon e.g. aluminium alloyed with about 8 to 11 wt.% of silicon and at most 4 wt.% of iron, optionally at most 0.2 wt.% of one or more additional elements such as calcium, unavoidable impurities, the remainder being aluminium.
  • Silicon is present in order to prevent the formation of a thick iron-metallic intermetallic layer which reduces adherence and formability.
  • Iron is preferably present in amounts between 1 and 4 wt.%, more preferably at least 2 wt.%.
  • an automotive component in particular an automotive chassis part, incorporating or made from the hot-rolled high-strength steel strip according to this invention and taking benefit from amongst others improved balance of strength, formability and the improved fracture toughness and reduced (edge-) crack susceptibility.
  • the steel strip can be shaped into an automotive component in a cold forming operation, warm forming and hot forming operation as are known in the art.
  • the automotive component includes a suspension arm, a reinforcement member, body-in-white frame member, as side member, a seat frame, a seat rail, bumper beam, battery boxes for electrical vehicles, all having an intricate shape.
  • the hot-rolled high-strength steel strip these components can be fabricated with high quality, cost efficient and high yields.
  • the high- strength hot-rolled steel product according to this invention can be used also for engineering applications.
  • Fig. 1A to Fig IE shows several features of the method to determine to average total crack length (ATCL) of a steel strip product using common cylindrical deep drawing tests for drawing cups.
  • FIG. 2A A schematic drawing of a hot-rolling mill for processing thick cast steel slabs is shown in Figure 2A, and a thin slab casting facility with a direct rolling mill is shown in Figure 2B.
  • the invention will now be illustrated with reference to non-limiting comparative and examples according to the invention.
  • the hot rolled steels were transferred to the run-out table with a start temperature run-out table (TSTART) in the range of 840 to 880°C and actively cooled from the austenitic phase field with a mixture of water and air to an end temperature in the ferritic phase field at the run-out table (TEND) in the range of 565 to 615°C at a cooling rate in the range of 30 to 70°C/s.
  • TSTART start temperature run-out table
  • TTD run-out table
  • the steels were transferred to a furnace to replicate slow coil cooling. This was done with furnace temperatures (CT - coiling temperature) of 540, 580, and 610°C (see Table 2).
  • Steels 1-3 (Alloy A) have all a composition according to the invention and wherein steel
  • the microstructure has about 2.6 vol.% of martensite and it is believed that this contributes to the good edge-crack resistance represented by ATCL of 34.8 mm.
  • ATCL edge-crack resistance
  • a too low coiling temperature (CT 540°C) for steel 9 results in a lower Rm compared to steel 8 and a significantly lower Rp and far too low hole expansion ratio.
  • Alloy D (steels 10-12) has an increased Al-content compared to alloy B (steels 4-6).
  • the comparison of steels 5 and 11 shows that an increased strength (Rm) will be obtained with the addition of Al.
  • Steel 11 also shows a favourable microstructure as illustrated by the MOD index, KAM values and sufficient degree of grain refinement as illustrated by ⁇ GB and consequently provides the desired balance of properties.
  • Alloy E (steels 13-15) has a purposive addition of V compared to alloy D (steels 10-12).
  • Steel 14 provides a further reduced edge-crack susceptibility compared to steel 11.
  • Comparing steel 14 with steel 15 shows that a lower coiling temperature (CT 540°C) results amongst others in a significantly reduced Rp.
  • CT 540°C coiling temperature
  • comparing steel 13 with steel 14 shows that increasing the CT to 610°C for steel 13 gives still a high Rm and Rp, but the edge-crack susceptibility is reduced to unacceptable levels (ATCL 56.3 mm). This is reflected amongst other by too low MOD index, too high KAM 0-1 and low KAM 1-5, and low ⁇ GB.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Sheet Steel (AREA)

Abstract

L'invention concerne une bande d'acier à haute résistance laminée à chaud ayant une composition constituée, en % en poids, de 0,02 à 0,13 % de C, de 1,20 à 3,50 % de Mn ; de 0,10 à 1,00 % de Si ; de 0,05 à 1,0 % de Mo ; de 0,02 à 0,70 % d'Al, de 0,04 à 0,25 % de Ti, jusqu'à 0,010 % de N, jusqu'à 0,02 % de P, jusqu'à 0,01 % de S, jusqu'à 0,005 % de B, éventuellement un ou plusieurs éléments choisis dans le groupe constitué de : (jusqu'à 1,5 % de Cu, jusqu'à 0,70 % de Cr, jusqu'à 0,50 % de Ni, jusqu'à 0,30 % de V, jusqu'à 0,10 % de Nb), le reste étant du Fe et des impuretés inévitables ; et la bande d'acier ayant une microstructure d'au moins 95 % en volume de ferrite et d'au plus 5 % en volume de martensite, et de préférence d'au moins 0,2 % de martensite ; ayant un indice de distribution de désorientation (MOD) d'au moins 0,65 à ¼ de l'épaisseur ; une fraction de superficie d'au plus 55 % avec une désorientation moyenne intragranulaire (Kernel Average Misorientation) (KAM) de 0 à 1 ; une fraction de superficie d'au moins 45 % avec une désorientation moyenne intragranulaire (KAM) de 1 à 5 ; et une longueur de joint de grain totale (∑GB [50-650]) d'au moins 1400 mm-1 ; et la bande d'acier ayant au moins les propriétés mécaniques suivantes : une résistance à la rupture (Rm) d'au moins 950 MPa, un allongement total (A50) d'au moins 10 %, et une valeur de rapport d'expansion de trou (λ) d'au moins 40 %. L'invention concerne également un procédé de fabrication d'une telle bande d'acier laminée à chaud, et une pièce automobile incorporant la bande d'acier laminée à chaud.
PCT/EP2023/051306 2022-01-25 2023-01-20 Bande d'acier à haute résistance laminée à chaud WO2023144019A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP22153227.8 2022-01-25
EP22153227 2022-01-25

Publications (1)

Publication Number Publication Date
WO2023144019A1 true WO2023144019A1 (fr) 2023-08-03

Family

ID=80775098

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2023/051306 WO2023144019A1 (fr) 2022-01-25 2023-01-20 Bande d'acier à haute résistance laminée à chaud

Country Status (1)

Country Link
WO (1) WO2023144019A1 (fr)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030063996A1 (en) * 2000-10-31 2003-04-03 Nkk Corporation High strength hot rolled steel sheet and method for manufacturing the same
EP1616970A1 (fr) 2003-04-21 2006-01-18 JFE Steel Corporation Tole d'acier lamine a chaud a haute resistance
WO2008102009A1 (fr) 2007-02-23 2008-08-28 Corus Staal Bv Feuillard d'acier à résistance élevée, laminé à froid et trempé en continu, et procédé de fabrication dudit feuillard
US20150099139A1 (en) * 2012-05-08 2015-04-09 Tata Steel Ijmuiden Bv Automotive chassis part made from high strength formable hot rolled steel sheet
US20180265939A1 (en) * 2015-09-22 2018-09-20 Tata Steel Ijmuiden B.V. A hot-rolled high-strength roll-formable steel sheet with excellent stretch-flange formability and a method of producing said steel

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030063996A1 (en) * 2000-10-31 2003-04-03 Nkk Corporation High strength hot rolled steel sheet and method for manufacturing the same
EP1338665A1 (fr) 2000-10-31 2003-08-27 Nkk Corporation Tole d'acier laminee a chaud presentant une resistance elevee a la traction et procede de fabrication
EP1616970A1 (fr) 2003-04-21 2006-01-18 JFE Steel Corporation Tole d'acier lamine a chaud a haute resistance
WO2008102009A1 (fr) 2007-02-23 2008-08-28 Corus Staal Bv Feuillard d'acier à résistance élevée, laminé à froid et trempé en continu, et procédé de fabrication dudit feuillard
US20150099139A1 (en) * 2012-05-08 2015-04-09 Tata Steel Ijmuiden Bv Automotive chassis part made from high strength formable hot rolled steel sheet
US20180265939A1 (en) * 2015-09-22 2018-09-20 Tata Steel Ijmuiden B.V. A hot-rolled high-strength roll-formable steel sheet with excellent stretch-flange formability and a method of producing said steel

Similar Documents

Publication Publication Date Title
JP6264507B2 (ja) 高強度亜鉛めっき鋼板及びその製造方法
CN109154044B (zh) 热浸镀锌钢板
US11946111B2 (en) Steel sheet, coated steel sheet, method for producing hot-rolled steel sheet, method for producing cold-rolled full hard steel sheet, method for producing heat-treated steel sheet, method for producing steel sheet, and method for producing coated steel sheet
EP1201780A1 (fr) Plaque d'acier presentant une excellente aptitude a l'ebarbage et une resistance elevee a la fatigue, et son procede de production
JP6485549B2 (ja) 高強度熱延鋼板
US20220056549A1 (en) Steel sheet, member, and methods for producing them
US11939642B2 (en) High-strength steel sheet and method for manufacturing same
KR102500089B1 (ko) 고강도 용융 아연 도금 강판 및 그의 제조 방법
KR20200106195A (ko) 고강도 강판 및 그 제조 방법
RU2712670C1 (ru) Стальной лист для горячей штамповки
US20220090247A1 (en) Steel sheet, member, and methods for producing them
WO2022071305A1 (fr) Tôle d'acier
JP5194930B2 (ja) 高降伏比高強度冷延鋼板
KR20230059816A (ko) 고강도 냉연 강판, 용융 아연 도금 강판 및 합금화 용융 아연 도금 강판, 및 이들의 제조 방법
WO2023144019A1 (fr) Bande d'acier à haute résistance laminée à chaud
US20230349020A1 (en) Steel sheet, member, and methods for manufacturing the same
WO2024032949A1 (fr) Bande d'acier à haute résistance laminée à chaud
WO2024048132A1 (fr) Tôle d'acier à haute résistance, son procédé de production, élément et son procédé de production
US20230081354A1 (en) High flangeable ultra-high strength ductile hot-rolled steel, method of manufacturing said hot-rolled steel and use thereof
WO2023181641A1 (fr) Tôle d'acier à haute résistance et son procédé de production
WO2023095870A1 (fr) Tôle d'acier galvanisée
WO2023181642A1 (fr) Tôle d'acier à haute résistance et son procédé de production
WO2024048131A1 (fr) Tôle d'acier galvanisée à haute résistance, son procédé de fabrication, élément et son procédé de fabrication
WO2024048133A1 (fr) Tôle d'acier à haute résistance et son procédé de production, et élément et son procédé de production
WO2023181643A1 (fr) Feuille d'acier à haute résistance et son procédé de fabrication

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 23701438

Country of ref document: EP

Kind code of ref document: A1