EP1735474B1 - Feuille d'acier laminee a froid et feuille d'acier traitee a chaud presentant une resistance et un durcissement a la cuisson superieurs et procede de fabrication de ces feuilles d'acier - Google Patents

Feuille d'acier laminee a froid et feuille d'acier traitee a chaud presentant une resistance et un durcissement a la cuisson superieurs et procede de fabrication de ces feuilles d'acier Download PDF

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EP1735474B1
EP1735474B1 EP05789750.6A EP05789750A EP1735474B1 EP 1735474 B1 EP1735474 B1 EP 1735474B1 EP 05789750 A EP05789750 A EP 05789750A EP 1735474 B1 EP1735474 B1 EP 1735474B1
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Prior art keywords
steel sheet
less
steel
hot
temperature
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EP1735474A1 (fr
EP1735474A4 (fr
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Seong-Ho Han
Tae-Kyu Kim
Sang-Ho Han
San-Kyung Ko
Kwang-Geun Chin
Hee-Jae Kang
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Posco Holdings Inc
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Posco Co Ltd
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    • 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
    • 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
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • 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
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium

Definitions

  • the present invention relates to a bake-hardenable cold-rolled steel sheet for automobile bodies, a hot-dipped steel sheet manufactured using the same, and a method for manufacturing the same. More particularly, the present invention relates to a bake-hardenable high-strength cold-rolled steel sheet having excellent bake hardenability, aging resistance at room temperature, and secondary work embrittlement resistance, a hot-dipped steel sheet manufactured using the same, and a method for manufacturing the same.
  • bake-hardenable cold-rolled steel sheets typically have a tensile strength of 390 MPa, and exhibit excellent ductility due t o the fact that their yield strength is approximately the same as that of mild steel upon press forming. Additionally, the bake-hardenable cold-rolled steel sheets have a characteristic in which the yield strength thereof is increased upon paint baking or coating treatment after press forming.
  • steel sheets are mainly used, which are manufactured by batch annealing low carbon, P-added, Al-killed steels, and have a bake hardening value of about 40 to 50 MPa.
  • the bake-hardenable cold-rolled steel sheets manufactured by the continuous annealing method are restrictively used for the exterior plates of the automobiles, which do not require the formability.
  • bake-hardenable cold-rolled steel sheets with improved formability by addition of intensive carbonitride-forming elements, such as Ti or Nb, to the Al-killed steel.
  • intensive carbonitride-forming elements such as Ti or Nb
  • the bake-hardenable cold-rolled steel sheets manufactured by the continuous annealing method are improved in the formability, the bake-hardenable cold-rolled steel sheets are increasingly utilized as exterior plates for automobiles which require dent resistance.
  • Japanese Unexamined Patent Publication No. (Sho) 61-26757 discloses an ultra low carbon bake-hardenable cold-rolled steel sheet, which comprises 0.0005 ⁇ 0.015 wt% of C; 0.05 wt% or less of S+N; and Ti and Nb or a compound thereof.
  • Japanese Unexamined Patent Publication No. (Sho) 57-89437 discloses a bake-hardenable cold-rolled steel sheet, which uses a Ti-added steel comprising 0.010 wt% or less of C, and has a bake hardening value of about 40 MPa.
  • the methods of the disclosures impart bake hardenability to the steel sheets while preventing deterioration of the other properties of the steel sheets by appropriately controlling the amount of solute elements in the steel through appropriate control of the added amount of Ti and Nb or the cooling rate during annealing.
  • U.S. Patent Nos. 5,556,485 and 5,656,102 disclose methods of manufacturing a bake-hardenable cold-rolled steel sheet using a Ti-V based ultra low carbon steel, which comprises 0.0005 - 0.1 wt% of C; 0 ⁇ 2.5 wt% of Mn; 0 - 0.5 wt% of Al; 0 ⁇ 0.04 wt% of N; 0 ⁇ 0.5 wt% of Ti; and 0.005 ⁇ 0.6 % of V.
  • V can create a carbide such as VC, since it does not sufficiently improve the formability due to its too low re-melting temperature, Ti is added in an amount of about 0.02 wt% or more in order to enhance the formability.
  • Japanese Unexamined Patent Publication No. (Hei) 5-93502 discloses a method for enhancing the bake hardenability through addition of Sn
  • Japanese Unexamined Patent Publication No. (Hei) 9-249936 discloses a method for enhancing the ductility of the steel by relieving stress concentration on grain boundaries through addition of V and Nb.
  • Japanese Unexamined Patent Publication No. (Hei) 8-49038 discloses a method for enhancing the formability through addition of Zr
  • Japanese Unexamined Patent Publication No. (Hei) 7-278654 discloses a method for enhancing the formability by increasing the strength while minimizing deterioration of work hardening index (N-value) through addition of Cr.
  • boron known as an element capable of enhancing the secondary work embrittlement resistance
  • boron is added in an amount of about 5 ppm to the steel, it is limited in its ability to enhance the secondary work embrittlement resistance due to the presence of excessive P content.
  • DBTT ductility-brittleness transition temperature
  • the steel sheets are usually subjected to electroplating or hot dipping.
  • electroplated steel sheet has good plating characteristics and excellent corrosion resistance
  • the electroplated steel sheet is very expensive in comparison to hot dipped steel sheets, and thus the hot dipped steel sheets are mainly used for automobiles.
  • the present invention has been made in view of the above problems, and it is an object of the invention to provide bake-hardenable high-strength cold-rolled steel sheets having bake hardenability, aging resistance, and secondary work embrittlement resistance by adding a small amount of Nb together with Al, Mo and B, while appropriately controlling of the Nb/C ratio and the grain size, hot-dipped steel sheets manufactured using the same, and a method for manufacturing the same.
  • a bake-hardenable cold-rolled steel sheet manufactured through hot rolling, cold rolling and continuous annealing of a steel, the steel sheet comprising: 0.0016 ⁇ 0.01 % of C; 0.1 % or less of Si; 0.2 ⁇ 1.5 % of Mn; 0.05 ⁇ 0.15 % of P; 0.01 % or less of S; 0.08 ⁇ 0.5 % of (soluble) Al; 0.0025 % or less of N; 0.003 ⁇ 0.1 % of Nb optionally 0.003 % of Ti; 0.01 ⁇ 0.4 % of Mo; 0.0005 ⁇ 0.005 % of B; and the balance of Fe and other unavoidable impurities, in terms of weight%, while satisfying an Nb/C ratio of 0.3 ⁇ 0.7, wherein the steel sheet has fine AlN precipitates formed upon hot rolling the steel, and a grain size(ASTM No.) of 9 or more, the fine Al
  • a hot-dipped steel sheet manufactured through hot rolling, cold rolling, continuous annealing, and hot dipping of a steel consisting of : 0.0016 ⁇ 0.01% of C; 0.1% or less of Si; 0.2 ⁇ 1.5% of Mn; 0.05 ⁇ 0.15 of P; 0.01 % or less of S; 0.08 ⁇ 0.5% of (soluble)Al; 0.0025% or less of N; 0.003 ⁇ 0.1% of Nb; 0 ⁇ 0.003 % of Ti; 0.01 ⁇ 0.4% of Mo; 0.0005 ⁇ 0.005% of B; and the balance of Fe and other unavoidable impurities, in terms of weight%, while satisfying an Nb/C ratio of 0.3 ⁇ 0.7, wherein the steel sheet has fine AlN precipitates formed upon hot rolling the steel, and a grain size(ASTM No.) of 9 or more, the fine AlN precipitates having a size acting as a barrier for suppressing grain growth during annea
  • a method for manufacturing a bake-hardenable high-strength cold-rolled steel sheet comprising the steps of: hot-rolling a steel slab with finish rolling at or above the Ar 3 transformation temperature to provide a hot rolled steel sheet after heating the steel slab to a temperature of 1,200 °C or more, the steel slab consisting of : 0.0016 ⁇ 0.01 % of C; 0.1 % or less of Si; 0.2 ⁇ 1.5 % of Mn; 0.05 ⁇ 0.15 % of P; 0.01 % or less of S; 0.08 ⁇ 0.5 % of (soluble) Al; 0.0025 % or less of N; 0.003 ⁇ 0.1 % of Nb; 0 ⁇ 0.003 % of Ti; 0.01 ⁇ 0.4 % of Mo; 0.0005 ⁇ 0.005 % of B; and the balance of Fe and other unavoidable impurities, in terms of weight%, while satisfying an Nb/C ratio of 0.3
  • a method for manufacturing a hot-dipped steel sheet comprising the steps of: hot-rolling a steel slab with finish rolling at or above an Ar 3 transformation temperature to provide a hot rolled steel sheet after heating the steel slab to a temperature of 1,200 °C or more, the steel slab comprising: 0.0016 ⁇ 0.01 % of C; 0.1 % or less of Si; 0.2 ⁇ 1.5 % of Mn; 0.05 ⁇ 0.15 % of P; 0.01 % or less of S; 0.08 ⁇ 0.5 % of (soluble) Al; 0.0025 % or less of N; 0.003 ⁇ 0.1 % of Nb; 0 ⁇ 0.003 % of Ti; 0.01 ⁇ 0.4 % of Mo; 0.0005 ⁇ 0.005 % of B; and the balance of Fe and other unavoidable impurities, in terms of weight%, while satisfying an Nb/C ratio of 0.3 ⁇ 0.7; coiling the hot-rolled steel sheet; cold
  • Requirements for a bake-hardenable cold-rolled steel sheet include a high bake hardening value, a low aging index at room temperature, and excellent secondary work embrittlement resistance.
  • Bake hardening or natural aging is a phenomenon occurring when interstitial elements exiting as solute elements in a steel, particularly, nitrogen or carbon, are fixed to dislocations generated during deformation.
  • contents of solute nitrogen and carbon are increased in the steel, a bake hardening value is also increased, with accompanying natural aging due to the excessive amount of solute elements, thereby causing deterioration of formability.
  • it is very important to optimize the amount of solute nitrogen and carbon in the steel.
  • nitrogen Since nitrogen has a higher diffusion speed in the steel than that of carbon, nitrogen affects the natural aging rather than carbon.
  • solute nitrogen is reduced in order to secure excellent aging resistance.
  • solute carbon For the solute carbon, if the amount of solute carbon is excessively lowered, the aging resistance is enhanced, whereas the bake hardenability is deteriorated. On the other hand, if the amount of solute carbon is excessively increased, the bake hardenability is enhanced, whereas the aging resistance is deteriorated.
  • the bake hardenability and the aging resistance may be differently exhibited according to a position of the solute carbon in the steel, that is, according to whether the solute carbon is located in grain boundaries or in grains, which will be described hereinafter.
  • the reason for the varying influence on the bake hardenability and the aging resistance according to the position of the solute carbon in the steel is related to the mobility of the solute carbon.
  • solute carbon When the solute carbon is located in grain, it can move relatively freely, thereby influencing not only the bake hardenability but also the aging resistance.
  • solute carbon in the grain boundary is located in a relatively stable position, it has minimal affects upon low temperature aging, but during high temperature baking, it is activated and affects the bake hardenability.
  • solute carbon in grain influences the aging resistance and the bake hardenability simultaneously, whereas the solute carbon in the grain boundary influences only the bake hardenability.
  • One of the features of the invention is appropriate control of the amount of solute carbon and the position thereof in the steel.
  • the contents of carbon and niobium are appropriately controlled in order to control the amount of solute carbon, and the grains are controlled to have a fine grain size so as to allow as much of the solute carbon in the steel as possible to be located in the grain boundaries.
  • Fig. 1 is a graph illustrating the relationship between variation in grain size and bake hardening (BH) value and an aging index (AI), as one of the results of studies performed by the inventors.
  • BH bake hardening
  • AI aging index
  • the inventors understood from the result of the studies that it is desirable to control the grains to have a grain size (ASTM No.) of 9 or more in order to minimize deterioration of the bake hardenability while maximizing the aging resistance.
  • Another feature of the invention is that the grains become finer through formation of fine AlN precipitates upon hot rolling.
  • the fine AlN precipitates are formed upon hot rolling, by addition of large quantities of Al to the steel, and suppress grain growth when annealing a cold-rolled steel sheet, thereby allowing the grains to become finer.
  • the Al content is appropriately controlled so as to allow the fine AlN precipitates to be formed upon hot rolling.
  • fine grains are more securely achieved by appropriately controlling the size of the AlN precipitates.
  • Al is known as a deoxidizer and/or a component added for fixing nitrogen by use of coarse AlN precipitates in a bake-hardenable steel.
  • the bake-hardenable steel wherein Al and N are combined to form the fine AlN precipitates upon hot rolling through appropriate control of Al content, thereby refining the grains, so that the solute carbon in the steel is located in the grain boundaries rather than in the grains, thereby ensuring the excellent aging resistance and bake hardenability at the same time, is not known in the art.
  • Al is a very effective element for providing the bake-hardenable steel.
  • Fig. 2 an example of variation of the bake hardening (BH) value and the aging index (AI) of a hot-dipped steel sheet according to variation of the amount of soluble aluminum is shown.
  • BH bake hardening
  • AI aging index
  • the soluble aluminum content is preferably in the range of 0.08 % or more.
  • a hot coiling temperature is appropriately selected for grain refining.
  • the hot coiling temperature When the hot coiling temperature is too high, the grains become coarse during coiling even if the composition of the steel, that is, contents of carbon, soluble aluminum, and niobium, is controlled. As a result, coarsening of the grains occurs during recrystallization annealing so that the grains have a grain size(ASTM No.) of 9 or less, thereby increasing the AI.
  • the hot coiling temperature is lowered below a certain degree, aging resistance at room temperature may be enhanced, but grain refining becomes excessive, possibly causing an increase of yield strength and deterioration of formability, by which elongation and r-value are decreased.
  • Still another feature of the invention is enhancement of secondary work embrittlement resistance through addition of appropriate amounts of Mo.
  • components for automobiles are formed to have a desired shape through repeated pressing.
  • Secondary work embrittlement means that cracks are formed during a secondary working process after a primary working process.
  • the cracks are caused by a phenomenon in which fractures are formed along the grain boundaries due to phosphorous (P), which is present in the grain boundaries of the steel and weakens coupling force between the grains.
  • P phosphorous
  • P is not added to the steel.
  • P is the solute element which provides the least reduction of elongation in comparison to an increase of strength, and, in particular, has an advantage in that it is low in price.
  • the present invention employs Mo in order to further enhance the secondary work embrittlement resistance.
  • Mo has an affinity to the solute elements in the steel, it suppresses diffusion of the solute elements toward dislocations when the steel is maintained for a long time at room temperature, thereby enhancing the aging resistance.
  • Fig. 3 is a graph showing one of the results obtained by analyzing the effect of enhancing the aging resistance through addition of Mo, and it can be seen from Fig. 3 that when Mo content is increased, the BH value is not significantly changed, whereas the AI is lowered, thereby enhancing the aging resistance.
  • the inventors induce an optimal composition of the elements in order to use the properties of Mo and to prevent the deterioration of the property through excessive addition of Mo.
  • the B content is appropriately controlled in order to enhance the secondary work embrittlement resistance.
  • various well-known technologies may be additionally applied in order to enhance the secondary work embrittlement resistance, one example of which is appropriate control of coiling temperature.
  • compositions of the steel according to the invention will now be described in detail.
  • Carbon (C) is an element for solid solution strengthening and bake hardening. If carbon content is excessively low, the tensile strength of the steel is significantly lowered, sufficient bake hardening effect is not secured due to a low absolute amount of carbon in the steel, and the secondary work embrittlement resistance is also deteriorated since the site competition effect between the solute carbon and P is removed.
  • the carbon content is preferably 0.0016 % or more in order to ensure an effect of carbon addition.
  • the upper limit of the carbon content is set to 0.01 %, and preferably to 0.0025 %.
  • the ability to control the carbon content to be in this range is realized in a level of 95 % or more in practice.
  • Si is an element for increasing the strength of the steel. However, as the silicon content is increased, deterioration of ductility becomes remarkable, and since silicon deteriorates hot dipping capability, it is advantageous to minimize the quantity of silicon added to the steel.
  • the silicon content is restricted to 0.1 % or less, and particularly to 0.02 % or less.
  • Mn is an element for preventing hot embrittlement caused by formation of FeS by completely precipitating sulfur in the steel into MnS while allowing the grains to be reduced in size without deteriorating the ductility, as well as strengthening the steel.
  • Mn is preferably added in the range of 0.2 % or more.
  • the formability is deteriorated due to solid solution strengthening as the strength of the steel is rapidly increased.
  • a great amount of oxides, such as MnO, and a number of coating defects, such as a stripe pattern are formed on the surface of the steel sheet during an annealing process, thereby deteriorating the properties of the steel including coating adherence.
  • the Mn content is preferably in the range of 0.2 ⁇ 1.5 %, and more particularly, in the range of 0.2 ⁇ 1.2 %.
  • Phosphorus (P) is a substitutional alloying element, which provides the highest solid solution strengthening effect, and serves to enhance the in-plane anisotropy index while improving the strength of the steel.
  • P causes the grains of a hot-rolled steel sheet to become finer, and then serves to promote development of the microstructure having (111) plane, which is advantageous in that it enhances the average r-value (plasticity-anisotropy index), during a subsequent annealing process.
  • the greater the amount of P the higher the bake hardenability due to the site competition effect between carbon and phosphorous in view of the bake hardenability: the greater the amount of P the higher the bake hardenability.
  • Sulfur (S) Sulfur content is preferably in the range of 0.01 % or less.
  • Aluminum (Al) Aluminum is an alloying element considered an important element of the present invention.
  • Al is generally used for deoxidizing and fixing the solute nitrogen in the steel.
  • Al is combined with N during hot rolling to form fine AlN precipitates in the steel, thereby suppressing the grain growth and thus promoting grain refining during the annealing process, thereby enhancing the aging resistance and bake hardenability.
  • the fine AlN precipitates suppress the grain growth together with the NbC precipitates during the annealing process, the grains can be further reduced in size, thereby providing excellent aging resistance and bake hardenability.
  • the Al content exceeds 0.1 %, and thus finer Al precipitates can be secured by addition of Al exceeding 0.1 %.
  • an upper limit of the Al content is preferably 0.5 %, and more preferably 0.12 %.
  • the AlN precipitates it is necessary for the AlN precipitates to have a size, which can serve as a barrier to suppress the grain growth during annealing of the cold-rolled steel sheets, and it is preferable that the AlN precipitates have an average size of 20 ⁇ m or less.
  • Nitrogen exists in a solute state before or after annealing, and deteriorates the formability of the steel. Furthermore, since nitrogen has a higher aging ability than other interstitial solute elements, it is necessary to fix nitrogen by use of Ti or Al.
  • the nitrogen content is restricted to 0.0025 % or less.
  • Titanium is typically added to the steel as a carbonitride-forming element, and forms nitrides such as TiN, sulfides such as TiS or Ti 4 C 2 S 2 , and carbides such as TiC, in the steel.
  • Ti is not added to the steel, and, if at all, the amount of Ti added to the steel is restricted to 0.003 % or less, which can fix a small amount of nitrogen under consideration that Ti is contained in a raw material of the steel, to the steel from equipment, and to the steel during a process.
  • Niobium is a very important element together with Al and Mo in the present invention.
  • Nb is an intensive carbonitride-forming element, and fixes carbon in the steel as NbC precipitates.
  • NbC precipitates are very fine in comparison to other precipitates, it acts as an intensive barrier to impede the grain growth during recrystallization annealing, thereby causing the grains to become finer.
  • the grains are refined by means of the NbC precipitates, and the amount of Nb is controlled so as to secure the bake hardenability by allowing the predetermined amount of solute carbon to remain in the steel.
  • the Nb content is preferably in the range of 0.003 ⁇ 0.1 %, and more preferably in the range of 0.003 ⁇ 0.011 %.
  • NbC precipitates is 30 nm or less.
  • the bake hardenability and the aging resistance at room temperature it is necessary to control not only the Nb content but also the Nb/C ratio at the same time, and according to the invention, it is necessary to control the Nb/C ratio to be in the range of 0.3 ⁇ 0.7.
  • the bake hardening value is lowered due to lack of an absolute amount of solute carbon in the steel, and in the case of a Nb/ C ratio of greater than 0.7, even though the bake hardening value is increased due to an increase of the amount of solute carbon in the steel, the aging index is also increased, thereby deteriorating the aging resistance at room temperature. Accordingly, it is necessary to limit the ratio of Nb/C to within the range of 0.3 ⁇ 0.7.
  • Molybdenum is another very important element in the present invention.
  • Mo serves to enhance the strength of the steel or to form an Mo-based carbide in the solute state in the steel.
  • Mo serves to increase the coupling force of the grain boundaries in the solute state in the steel, thereby preventing fracture of the grain boundaries caused by P, that is, enhancing the secondary work embrittlement resistance, and suppresses the diffusion of carbon by virtue of affinity with carbon, thereby enhancing the aging resistance.
  • the Mo content is preferably in the range of 0.01 ⁇ 0.4 %, and more preferably in the range of 0.01 ⁇ 0.1%.
  • Boron is an interstitial element, and is located within the steel. B is in the solute state in the grain boundaries or combined with nitrogen to form the nitride of BN.
  • the amount of B is preferably in the range of 0.0005 ⁇ 0.005 %, and more preferably in the range of 0.0005 ⁇ 0.0015 %.
  • the steel sheet of the invention must have a grain size(ASTM No.) of 9 or more while satisfying the compositions as described above.
  • the amount of solute carbon in the grain boundaries is increased, thereby allowing the bake hardenability to be further enhanced while maintaining excellent aging resistance at room temperature.
  • the steel sheet of the invention has a greater amount of solute carbon in the grain boundaries rather than in the grains.
  • a preferable amount of solute carbon in grain is approximately 3 ⁇ 6 ppm.
  • the size of AlN precipitates formed during hot rolling is preferably 20 ⁇ m or less.
  • the steel sheet of the invention has excellent bake hardenability, aging resistance, secondary work embrittlement resistance, and a tensile strength of 300 MPa or more.
  • a steel slab is manufactured through continuous casting of the molten steel, and is then heated to a temperature of 1,200 °C or more.
  • the heated steel slab is subjected to hot-rolling with finish rolling at or above the Ar 3 transformation temperature, preferably at a temperature of 900 ⁇ 950 °C, which is immediately above the Ar 3 transformation temperature, thereby providing a hot rolled steel sheet
  • Heating of the steel slab to the temperature of 1,200 °C or more is for the purpose of providing sufficiently homogeneous austenite structure to the steel slab before hot rolling.
  • the structure of the steel may have combined grains instead of homogeneous austenite grains, causing deterioration of the properties of the steel.
  • finish hot rolling temperature is too low, the top and tail portions, and edges of a hot coil become single-phase regions, respectively, thereby increasing the in-plane anisotropy while deteriorating the formability of the steel. If the finish hot rolling temperature is excessively high, remarkably coarse grains are formed in the steel, so that defects such as orange peels can be easily formed on the surface of the steel sheet after working.
  • finish hot rolling temperature must be established on the basis of these viewpoints as described above.
  • the hot coiling temperature must be established on the basis of these viewpoints as described above.
  • the hot coiling temperature is in the range of 550 ⁇ 650 °C, and more preferably in the range of 600 ⁇ 650 °C.
  • a reduction rate is preferably 70 ⁇ 80 %.
  • the reduction rate is maintained at 70% or more for the purpose of enhancing the formability of the steel sheet, in particular, the r-value, together with the aging resistance by virtue of grain refining.
  • the cold-rolled steel sheet is subjected to continuous annealing by a typical method.
  • Continuous annealing of the invention is performed at about a temperature of 770 ⁇ 830°C.
  • annealing is preferably performed at a temperature of 770 °C or more.
  • the annealed cold-rolled steel sheet is cooled to room temperature after continuous annealing, and is then subjected to hot dipping.
  • the cold-rolled steel sheet is cooled from the continuous annealing temperature to the hot dipping temperature, and is then subjected to hot dipping.
  • hot dipping is not limited to particular conditions, and is performed by a typical method.
  • a hot dipping temperature is typically in the rage of about 450 ⁇ 500 °C.
  • the hot dipped steel sheet is subjected to temper rolling.
  • temper rolling is performed in order to ensure the aging resistance at room temperature together with appropriate bake hardenability.
  • the temper rolling ratio is a little higher than typical temper rolling, and preferably in the range of 1.2 ⁇ 1.5 %.
  • the reason of a little higher temper rolling ratio than the typical temper rolling is for preventing deterioration of the aging resistance due to the solute carbon in the steel.
  • the temper rolling ratio must be established in view of the aging resistance at room temperature and the coating adherence.
  • the hot rolled steel sheets were coiled under the conditions shown in Table 2, and subjected to cold rolling and annealing. Then, the annealed cold-rolled steel sheets were subjected to hot dipping at a temperature of 450 °C, followed by temper rolling at a temper rolling ratio of about 1.5 %. Next, a bake hardening (BH) value, an aging index (AI), a grain size (ASTM No.), a size of AlN precipitates, and a ductility-brittleness transition temperature (DBTT) were measured. Results thereof are shown in Table 2.
  • BH bake hardening
  • AI aging index
  • ASTM No. grain size
  • DBTT ductility-brittleness transition temperature
  • the conventional steel is a steel comprising 0.0019 wt% of C; 0.63 wt% of Mn; 0.056 wt% of P; 0.03 wt% of soluble Al; 0.005 wt% of Ti; 0.006 wt% of Nb, and 0.014 wt% of N.
  • an as-received curve is a stress-strain curve for the tensile strength of the steel measured immediately after being manufactured
  • a 180-days aged curve is a stress-strain curve for the tensile strength of the steel measured after transportation of the steel to Thailand and storage for 6 months.
  • Inventive steel Nos. 1 to 10 have a grain size(ASTM No.) of 9.8 ⁇ 12.5, and have AlN precipitates with an average size of 20 ⁇ m or less.
  • the Inventive steel No. 8 has very fine grains while having a very uniform distribution of grains over the microstructure.
  • the grains of the inventive steels are very fine, and this is because the inventive steels have a greater content of Al than the comparative steel so that fine AlN precipitates are formed in the inventive steels, and suppress grain growth upon recrystallization annealing together with NbC precipitates.
  • the bake hardening value is in the range of 38.1 ⁇ 58.4 MPa, and the AI for evaluating the aging resistance at room temperature is in the range of 8.0 ⁇ 29.1 MPa. Accordingly, it can be appreciated that balance between the BH value and the aging resistance is excellent.
  • the DBTT at the drawing ratio of 2.0 is in the range of -40 ⁇ -70 °C.
  • the Inventive steel No. 8 has an excellent DBTT caused by an increase of coupling force between the grains due to addition of Mo, in comparison to Comparative steel No. 6 and the conventional steel.
  • the Inventive steel No. 8 has an excellent aging resistance under long-term duration of 6 months or more at a high temperature
  • inventive steels have excellent bake hardenability and secondary work embrittlement resistance, and are not deteriorated due to aging under long-term duration of 6 months or more at a high temperature of the tropic region.
  • Comparative steel No. 1 has a carbon content of 0.0054 wt% higher than the carbon content of the invention in the range of 0.0016 ⁇ 0.0025 %.
  • the Comparative steel No. 1 has an excellent DBTT and a significantly high BH value, it has an AI of 30 MPa, and thus, it can be seen that the aging resistance is significantly deteriorated. That is, although the Comparative steel No. 1 has a grain size of ASTM No. 11.2, and has very fine grains that satisfy the requirement for grains size of the invention, the high content of solute carbon in the steel causes the aging resistance of the Comparative steel No. 1 to be deteriorated.
  • Comparative steel No. 2 has a soluble Al content of 0.04 wt%, which is lower than the Al content of the invention in the range of 0.08 ⁇ 0.12 %, and a Ti content of 0.025 %, which is higher than the Ti content of the invention.
  • the Comparative steel No. 2 has large grains, a low BH value, and a deteriorated DBTT.
  • the grain refining effect by virtue of the AlN precipitates, and the effect of enhancing the BH value were not achieved.
  • the high content addition of Ti causes most of the carbon added to the steel to be precipitated as TiC, so that the bake hardenability is hardly imparted to the steel, and reduction of the solute carbon in the steel also causes the site competition effect between C and P to be lowered, thereby deteriorating the DBTT.
  • Comparative steel No. 3 satisfies the composition of the invention, but has a carbon content of 0.0012 wt%, which is lower than the carbon content of the invention.
  • the Comparative steel No. 3 has coarse grains, low BH value and AI, and a deteriorated DBTT of 20 °C.
  • Comparative steel No. 4 has a soluble Al content lower than that of the invention, and an Nb content higher than that of the invention.
  • the Comparative steel No. 4 For the Comparative steel No. 4, the grain refining effect by virtue of Al, and the effect of enhancing the BH value were not achieved. Furthermore, although the Comparative steel No. 4 has a grain size of ASTM No. 9.1 that satisfies the requirement for grain size of the invention, it can be seen that the excessive addition of Nb causes excessive generation of NbC precipitates, and lack of the solute carbon in the steel, so that the BH value is not obtained at all, and the DBTT is significantly deteriorated.
  • Comparative steel No. 5 does not comprise Mo and B at all, and the effect of enhancing the secondary work embrittlement resistance by virtue of Mo and B is thus not expected in the Comparative steel No. 5.
  • Comparative steel No. 5 has excellent BH and AI values, it has a significantly deteriorated DBTT due to non-addition of Mo and B.
  • Comparative steel No. 6 has a soluble Al content lower than that of invention, and does not comprise Mo at all. It can be seen that although the Comparative steel No. 6 has excellent BH value and AI, it has a deteriorated DBTT due to decrease of the coupling force between the grains caused by non-addition of Mo compared with a high content of P.
  • Comparative steel No. 7 has a soluble Al content lower than that of invention, and does not comprise Mo and M at all.
  • the Comparative steel No. 7 has a BH of 34.1, and an AI of 22.8. It has a deteriorated DBTT due to non-addition of Mo and B.
  • Comparative steel No. 8 has a P content 0.12 % higher than that of the invention in the range of 0.05 ⁇ 0.11 %, and does not comprise B. It can be seen that, although the DBTT of the Comparative steel No. 8 is enhanced by virtue of Mo, the effect of enhancing the DBTT is limited due to high content addition of P, and in particular, the DBTT is still negative due to non-addition of B.
  • Comparative steel No. 9 does not comprise Mo, and has an AI of 33.4 MPa. It can be seen that the aging resistance is deteriorated.
  • Comparative steel No. 10 has an Nb/C ratio lower than that of the invention. Although it has excellent bake hardenability due to a high BH value, it also has deteriorated aging resistance due to a high AI.
  • Samples were manufactured following the same compositions and manufacturing conditions as those of the Inventive steel No. 8 as shown in Tables 1 and 2 except that the ratio of Nb/C was changed as shown in Fig. 7 . Then, the BH value and AI were measured according to variation of the ratio of Nb/C, and results thereof are shown in Fig. 7 .
  • the Nb/C ratio must be in the range of 0.3 ⁇ 0.7 in order to secure a BH value of 30 MPa or more and an AI of 30 MPa or less.
  • the bake-hardenable high-strength cold-rolled steel sheets having excellent bake hardenability, aging resistance, and secondary work embrittlement resistance, and the hot-dipped steel sheets using the same may be provided.

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Claims (14)

  1. Tôle d'acier laminé à froid à haute résistance durcissable par cuisson fabriquée par laminage à chaud, laminage à froid et recuit continu d'un acier, composée de 0,0016-0,01 % de C ; 0,1 % ou moins de Si ; 0,2-1,5 % de Mn ; 0,05-0,15 % de P ; 0,01 % ou moins de S ; 0,08-0,5 % d'Al soluble ; 0,0025 % ou moins de N ; 0,003-0,1 % de Nb ; 0,01-0,4 % de Mo ; 0,0005-0,005 % de B ; éventuellement 0,003 % ou moins de Ti et pour le reste de Fe et d'autres inévitables impuretés, exprimés en pourcentages pondéraux, tout en satisfaisant un rapport atomique Nb/C de 0,3-0,7, la tôle d'acier ayant des précipités de NbC ayant une taille moyenne de 30 nm ou moins, à l'exclusion de 0 nm, et la tôle d'acier ayant une granulométrie ASTM de 9 ou plus, une résistance à la traction de 300 MPa ou plus, et de fins précipités d'AlN formés lors du laminage à chaud de l'acier, les fins précipités d'AlN ayant une taille moyenne de 20 µm ou moins, à l'exclusion de 0 µm, agissant comme une barrière pour supprimer la croissance des grains lors du recuit de la tôle d'acier.
  2. Tôle d'acier selon la revendication 1, dans laquelle la teneur en Al est supérieure à 0,1 % et inférieure ou égale à 0,5 %.
  3. Tôle d'acier selon la revendication 1 ou 2, la tôle d'acier comprenant de plus grandes quantités de carbone en solution dans le joint de grain que dans le grain, et la quantité de carbone en solution dans le grain se situant dans la fourchette de 3-6 ppm.
  4. Tôle d'acier selon la revendication 1, composée de 0,0016-0,0025 % de C ; 0,02 % ou moins de Si ; 0,2-1,2 % de Mn ; 0,05-0,11 % de P ; 0,01 % ou moins de S ; 0,08-0,12 % d'Al soluble ; 0,0025 % ou moins de N ; 0,003-0,011 % de Nb ; 0,01-0,1 % de Mo ; 0,0005-0,0015 % de B ; éventuellement 0,003 % ou moins de Ti et pour le reste de Fe et d'autres inévitables impuretés, exprimés en pourcentages pondéraux, une valeur de durcissement à la cuisson BH de 30 MPa ou plus, un indice de vieillissement AI de 30 MPa ou moins, une température de transition ductilité-fragilité DBTT de -30 °C ou moins à un rapport d'étirage de 2,0, et une résistance à la traction de 340-390 MPa.
  5. Tôle d'acier selon la revendication 4, la tôle d'acier comprenant de plus grandes quantités de carbone en solution dans le joint de grain que dans le grain, et la quantité de carbone en solution dans le grain se situant dans la fourchette de 3-6 ppm.
  6. Tôle d'acier selon la revendication 1, la tôle d'acier étant également traitée dans un procédé de trempage à chaud, la tôle d'acier étant ainsi une tôle d'acier trempé à chaud.
  7. Tôle d'acier selon la revendication 6, dans laquelle la teneur en Al est supérieure à 0,1 % et inférieure ou égale à 0,5 %.
  8. Tôle d'acier selon la revendication 6 ou 7, la tôle d'acier comprenant de plus grandes quantités de carbone en solution dans le joint de grain que dans le grain, et la quantité de carbone en solution dans le grain se situant dans la fourchette de 3-6 ppm.
  9. Tôle d'acier selon la revendication 6, la tôle d'acier trempé à chaud étant composée de 0,0016-0,0025 % de C ; 0,02 % ou moins de Si ; 0,2-1,2 % de Mn ; 0,05-0,11 % de P ; 0,01 % ou moins de S ; 0,08-0,12 % d'Al soluble ; 0,0025 % ou moins de N ; 0,003-0,011 % de Nb ; 0,01-0,1 % de Mo ; 0,0005-0,0015 % de B ; éventuellement 0,003 % ou moins de Ti et pour le reste de Fe et d'autres inévitables impuretés, exprimés en pourcentages pondéraux, et ayant une valeur de durcissement à la cuisson BH de 30 MPa ou plus, un indice de vieillissement AI de 30 MPa ou moins, une température de transition ductilité-fragilité DBTT de - 30 °C ou moins à un rapport d'étirage de 2,0, et une résistance à la traction de 340-390 MPa.
  10. Tôle d'acier selon la revendication 9, la tôle d'acier comprenant de plus grandes quantités de carbone en solution dans le joint de grain que dans le grain, et la quantité de carbone en solution dans le grain se situant dans la fourchette de 3-6 ppm.
  11. Procédé de fabrication d'une tôle d'acier laminé à chaud à haute résistance durcissable par cuisson ayant une granulométrie ASTM de 9 ou plus et une résistance à la traction de 300 MPa ou plus, la tôle d'acier ayant des précipités de NbC ayant une taille moyenne de 30 nm ou moins, à l'exclusion de 0 nm, et de fins précipités d'AIN ayant une taille moyenne de 20 µm ou moins, à l'exclusion de 0 µm ;
    le procédé comprenant les étapes consistant à :
    laminer à chaud une brame d'acier avec un laminage de finition à ou au-dessus d'une température de transformation Ar3 pour obtenir une tôle d'acier laminé à chaud après chauffage de la brame d'acier jusqu'à une température de 1200 °C ou plus, la brame d'acier étant composée de 0,0016-0,01 % de C, 0,1 % ou moins de Si, 0,2-1,5 % de Mn, 0,05-0,15 % de P, 0,01 % ou moins de S, 0,08-0,5 % d'Al soluble, 0,0025 % ou moins de N, 0,003-0,1 % de Nb, 0,01-0,4 % de Mo, 0,0005-0,005 % de B, éventuellement 0,003 % ou moins de Ti et pour le reste de Fe et d'autres inévitables impuretés, exprimés en pourcentages pondéraux, tout en satisfaisant un rapport atomique Nb/C de 0,3-0,7 ;
    enrouler la tôle d'acier laminé à chaud à une température de 550 °C à 650 °C ;
    laminer à froid la tôle d'acier laminé à chaud ; et
    recuire en continu la tôle d'acier laminé à froid à une température de 770 °C à 830 °C.
  12. Procédé selon la revendication 11, comprenant les étapes consistant à :
    laminer à chaud une brame d'acier avec un laminage de finition à une température de 900-950 °C pour obtenir une tôle d'acier laminé à chaud, après homogénéisation de la brame d'acier à une température de 1200 °C ou plus, la brame d'acier étant composée de 0,0016-0,0025 % de C, 0,02 % ou moins de Si, 0,2-1,2 % de Mn, 0,05-0,11 % de P, 0,01 % ou moins de S, 0,08-0,12 % d'Al soluble, 0,0025 % ou moins de N, 0,003-0,011 % de Nb, 0,01-0,1 % de Mo, 0,0005-0,0015 % de B, éventuellement 0,003 % ou moins de Ti et pour le reste de Fe et d'autres inévitables impuretés, exprimés en pourcentages pondéraux ;
    enrouler la tôle d'acier laminé à chaud à une température de 600-650 °C ;
    laminer à froid la tôle d'acier laminé à chaud à un taux de réduction de 75-80 % ; et
    recuire en continu la tôle d'acier laminé à froid à une température de 770-830 °C.
  13. Procédé selon la revendication 11, comprenant en outre les étapes consistant à :
    tremper à chaud la tôle d'acier recuit ; et
    écrouir la tôle d'acier trempé à chaud.
  14. Procédé selon la revendication 13, comprenant les étapes consistant à :
    laminer à chaud une brame d'acier avec un laminage de finition à une température de 900-950 °C pour obtenir une tôle d'acier laminé à chaud, après homogénéisation de la brame d'acier à une température de 1200 °C ou plus, la brame d'acier étant composée de 0,0016-0,0025 % de C, 0,02 % ou moins de Si, 0,2-1,2 % de Mn, 0,05-0,11 % de P, 0,08-0,12 % d'Al soluble, 0,003-0,011 % de Nb, 0,01-0,1 % de Mo, 0,0005-0,0015 % de B, éventuellement 0,003 % ou moins de Ti et pour le reste de Fe et d'autres inévitables impuretés, exprimés en pourcentages pondéraux ;
    laminer à chaud une brame d'acier avec un laminage de finition à une température de 900-950 °C pour obtenir une tôle d'acier laminé à chaud, après homogénéisation de la brame d'acier à une température de 1200 °C ou plus,
    enrouler la tôle d'acier laminé à chaud à une température de 600-650 °C ;
    laminer à froid la tôle d'acier laminé à chaud à un taux de réduction de 75-80 % ;
    recuire en continu la tôle d'acier laminé à froid à une température de 770-830 °C ;
    tremper à chaud la tôle d'acier recuit ; et
    écrouir la tôle d'acier trempé à chaud à un taux de réduction de 1,2-1,5 %.
EP05789750.6A 2004-03-25 2005-03-22 Feuille d'acier laminee a froid et feuille d'acier traitee a chaud presentant une resistance et un durcissement a la cuisson superieurs et procede de fabrication de ces feuilles d'acier Active EP1735474B1 (fr)

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PCT/KR2005/000828 WO2006001583A1 (fr) 2004-03-25 2005-03-22 Feuille d'acier laminee a froid et feuille d'acier traitee a chaud presentant une resistance et un durcissement a la cuisson superieurs et procede de fabrication de ces feuilles d'acier

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Families Citing this family (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100685030B1 (ko) * 2005-07-08 2007-02-20 주식회사 포스코 내2차가공취성, 피로특성 및 도금특성이 우수한 심가공용박강판 및 그 제조방법
EP2492363B1 (fr) * 2005-09-23 2013-11-27 Posco Tôle d'acier laminée à froid durcissant au four de résistance supérieure et procédé de fabrication de la tôle d'acier laminée à froid
KR100685037B1 (ko) * 2005-09-23 2007-02-20 주식회사 포스코 내시효성이 우수한 고장력 소부경화형 냉간압연강판,용융도금강판 및 냉연강판의 제조방법
KR100775339B1 (ko) * 2006-11-21 2007-11-08 주식회사 포스코 면내이방성 및 가공성이 우수한 냉연강판 및 그 제조방법
KR20080061855A (ko) * 2006-12-28 2008-07-03 주식회사 포스코 딥드로잉성이 우수한 복합조직강판
KR101105040B1 (ko) * 2008-06-23 2012-01-16 주식회사 포스코 표면특성 및 내2차 가공취성이 우수한 소부경화강 및 그 제조방법
KR101348857B1 (ko) 2010-11-29 2014-01-07 신닛테츠스미킨 카부시키카이샤 고강도 베이킹 경화형 냉연 강판 및 그 제조 방법
WO2012147843A1 (fr) * 2011-04-28 2012-11-01 東洋鋼鈑株式会社 Feuille d'acier traitée en surface pour boîtiers de batterie, boîtier de batterie et batterie
WO2016195456A1 (fr) * 2015-06-05 2016-12-08 주식회사 포스코 Tôle d'acier mince de haute résistance présentant une excellente aptitude à l'étirage et au durcissement après cuisson et son procédé de fabrication
KR101758557B1 (ko) 2015-06-05 2017-07-18 주식회사 포스코 드로잉성 및 소부경화성이 우수한 고강도 박강판 및 그 제조방법
WO2018073116A2 (fr) * 2016-10-17 2018-04-26 Tata Steel Ijmuiden B.V. Procédé de production d'une bande d'acier pour pièces peintes
CN109844159B (zh) 2016-10-17 2021-09-07 塔塔钢铁艾默伊登有限责任公司 用于涂漆零件的钢
US20200087761A1 (en) * 2016-10-17 2020-03-19 Tata Steel Ijmuiden B.V. Steel substrate for painted parts
CN109283053A (zh) * 2018-11-01 2019-01-29 唐山钢铁集团有限责任公司 超低碳烘烤硬化用钢的时效性评价方法
WO2020142110A1 (fr) * 2018-12-31 2020-07-09 Intel Corporation Systèmes de sécurisation utilisant une intelligence artificielle
CN114262844A (zh) * 2021-12-03 2022-04-01 本钢板材股份有限公司 低成本220bh冷轧烘烤硬化钢及其制备方法

Family Cites Families (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6046166B2 (ja) * 1980-11-26 1985-10-15 川崎製鉄株式会社 焼付硬化性を有する良加工性冷延鋼板の製造方法
JPH04120217A (ja) * 1990-09-11 1992-04-21 Nippon Steel Corp 焼付硬化性に優れた冷延鋼板の製造方法
JPH04131357A (ja) * 1990-09-21 1992-05-06 Nippon Steel Corp 焼付硬化性に優れた非時効性の深絞り用薄鋼板およびその製造方法
US5356494A (en) * 1991-04-26 1994-10-18 Kawasaki Steel Corporation High strength cold rolled steel sheet having excellent non-aging property at room temperature and suitable for drawing and method of producing the same
JPH0525549A (ja) * 1991-07-22 1993-02-02 Nippon Steel Corp 焼付硬化性に優れた冷延鋼板の製造方法
JPH05171353A (ja) * 1991-07-30 1993-07-09 Nippon Steel Corp 焼付け硬化性に優れた深絞り用薄鋼板およびその製造方法
JPH0681045A (ja) * 1992-01-23 1994-03-22 Nippon Steel Corp 加工性および焼付硬化性に優れた冷延鋼板の製造方法
JP3249572B2 (ja) * 1992-04-15 2002-01-21 川崎製鉄株式会社 常温遅時効性を有する焼付硬化型薄鋼板
JP3046145B2 (ja) * 1992-07-02 2000-05-29 新日本製鐵株式会社 深絞り用冷延鋼板の製造方法
JPH07188856A (ja) * 1993-12-28 1995-07-25 Nippon Steel Corp 常温遅時効性と焼付硬化性に優れた冷延鋼板
US5556485A (en) * 1994-11-07 1996-09-17 Bethlehem Steel Corporation Bake hardenable vanadium containing steel and method of making thereof
US5656102A (en) * 1996-02-27 1997-08-12 Bethlehem Steel Corporation Bake hardenable vanadium containing steel and method thereof
JPH10130733A (ja) * 1996-10-22 1998-05-19 Kawasaki Steel Corp 時効劣化の少ない焼き付け硬化性鋼板の製造方法
JP3769914B2 (ja) * 1998-01-06 2006-04-26 Ｊｆｅスチール株式会社 耐時効性と焼き付け硬化性に優れた缶用鋼板
JP3793351B2 (ja) * 1998-06-30 2006-07-05 新日本製鐵株式会社 焼付硬化性に優れた冷延鋼板
JP2000167615A (ja) * 1998-12-03 2000-06-20 Toshiba Corp 巻取温度制御方法及び制御装置
BR0210265B1 (pt) * 2001-06-06 2013-04-09 folha de aÇo galvanizado ou galvanelado com imersço a quente.
CN1169991C (zh) * 2001-10-19 2004-10-06 住友金属工业株式会社 具有优异的可加工性和成型精度的薄钢板及其制造方法
KR100544645B1 (ko) * 2001-12-24 2006-01-24 주식회사 포스코 가공성이 우수한 복합조직 냉연강판 제조방법
JP3921100B2 (ja) * 2002-02-27 2007-05-30 新日本製鐵株式会社 常温遅時効性と焼付硬化性に優れた薄鋼板
CA2469022C (fr) * 2002-06-25 2008-08-26 Jfe Steel Corporation Tole d'acier a haute resistance laminee a froid et methode de fabrication connexe
KR100946067B1 (ko) * 2002-12-27 2010-03-10 주식회사 포스코 내시효성이 우수한 용융도금용 소부경화형 냉연강판제조방법

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JP2007530783A (ja) 2007-11-01
US20090272468A1 (en) 2009-11-05
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US20070181232A1 (en) 2007-08-09
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