WO1999055927A1 - Plaque d'acier laminee a froid possedant d'excellentes caracteristiques d'aptitude au moulage et de formabilite en panneaux, une bonne resistance a la constriction, plaque d'acier a placage en zinc moule et procede de fabrication de ces plaques - Google Patents

Plaque d'acier laminee a froid possedant d'excellentes caracteristiques d'aptitude au moulage et de formabilite en panneaux, une bonne resistance a la constriction, plaque d'acier a placage en zinc moule et procede de fabrication de ces plaques Download PDF

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Publication number
WO1999055927A1
WO1999055927A1 PCT/JP1998/004283 JP9804283W WO9955927A1 WO 1999055927 A1 WO1999055927 A1 WO 1999055927A1 JP 9804283 W JP9804283 W JP 9804283W WO 9955927 A1 WO9955927 A1 WO 9955927A1
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WO
WIPO (PCT)
Prior art keywords
hot
steel sheet
cold
panel
rolled steel
Prior art date
Application number
PCT/JP1998/004283
Other languages
English (en)
Japanese (ja)
Inventor
Fusato Kitano
Masaya Morita
Yoshihiro Hosoya
Takeshi Fujita
Tadashi Inoue
Masahiro Iwabuchi
Takeo Ishii
Original Assignee
Nkk Corporation
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 Nkk Corporation filed Critical Nkk Corporation
Priority to BR9810485-3A priority Critical patent/BR9810485A/pt
Priority to DE69840595T priority patent/DE69840595D1/de
Priority to US09/446,708 priority patent/US6524726B1/en
Priority to EP98944222A priority patent/EP1002884B1/fr
Publication of WO1999055927A1 publication Critical patent/WO1999055927A1/fr

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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
    • 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
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
    • C21D8/0421—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the working steps
    • C21D8/0426—Hot rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
    • C21D8/0421—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the working steps
    • C21D8/0436—Cold rolling
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
    • C23C2/022—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by heating
    • C23C2/0224—Two or more thermal pretreatments
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
    • C23C2/024—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by cleaning or etching

Definitions

  • the present invention relates to a cold-rolled steel sheet, a hot-dip galvanized steel sheet, and a method for producing the same, which are excellent in formability, panel shape, and dent resistance required for an automobile outer panel.
  • Steel sheets for automobile outer panels are required to have excellent formability, shape after panel forming, and dent resistance (resistance to local dents). Press formability is evaluated by indexes such as steel sheet yield strength, elongation, and n value (work hardening index). Panel shape and dent resistance are often evaluated by the yield strength of the material and the yield strength after processing and baking. If the yield strength of the steel sheet is low, press formability is good, but it is disadvantageous for dent resistance after panel forming. However, when the yield strength is high, on the other hand, although it is advantageous for dent resistance, there are problems in press forming such as wrinkles and cracks.
  • BH steel sheet paint bake hardening type cold rolled steel sheet (Bake) utilizing the strain aging phenomenon of carbon (C) in steel.
  • C strain aging phenomenon of carbon
  • a BH steel sheet with high deep drawability based on a very low carbon steel with a carbon content of about 50 ppm, cold-rolled with carbon nitride forming elements such as Nb and Ti added at a C equivalent ratio of 1 or less.
  • Methods for producing rolled steel sheets are known.
  • Japanese Patent Publication No. 60-46166 discloses a technique for annealing Nb or Ti-added ultra-low carbon steel at a high temperature near 900 ° C.
  • Japanese Patent Application Laid-Open No. 61-2766928 discloses a technology for producing an Nb-added ultra-low carbon BH steel sheet by annealing in a temperature range around 700 to 850 ° C. Is disclosed.
  • 61-2766928 is preferable in terms of ensuring surface properties and material yield strength because the annealing temperature is relatively lower than the former, but the r value and BH There is a limit to the improvement of
  • all of these conventional technologies focus on increasing the BH of steel sheets with the aim of improving dent resistance, deterioration in normal temperature aging resistance (yield point during storage at normal temperature) (E.g., strain strain during press forming due to the development of elongation). For this reason, the amount of BH is limited to 6 OMPa or less from a practical viewpoint. I can do it.
  • the cold-rolled steel sheet manufactured by the conventional technology sufficiently satisfies the good surface properties, room-temperature aging resistance, and panel dent resistance required for steel sheets for automobile outer panels. .
  • An object of the present invention is to provide a cold-rolled steel sheet, a hot-dip galvanized steel sheet, and a method for producing the same, which are excellent in steel sheet surface properties, room-temperature aging resistance, and panel dent resistance required for steel sheets for automobile outer panels.
  • the cold-rolled steel sheet of the present invention is, in terms of% by weight, C: 0, 0.05 to 0.015%, Si: 0.01 to 0.2%, and Mn: 0. 2 to 1.5%, P: 0.01 to 0.07%, S: 0.06 to 0.015%, sol.A1: 0.01 to 0. 0 8%, 0 4%, O ⁇ 0.003%, Nb: 0.04 to 0.23%, and Nb and C are expressed by the following formula (1).
  • the formability, panel shape, and durability are characterized by containing steel within the range that satisfies, the balance being substantially a steel composition consisting of Fe and unavoidable impurities, and satisfying the following expression (2). Cold rolled steel sheet with excellent dent properties.
  • the cold-rolled steel sheet of the present invention is characterized in that the cold-rolled steel sheet further contains B: 0.0001 to 0.002% by weight. This is a cold-rolled steel sheet with excellent formability, panel shape, and dent resistance as described in (1).
  • the hot-dip galvanized steel sheet of the present invention is obtained by subjecting the cold-rolled steel sheet according to the above (1) or (2) to hot-dip galvanizing, comprising: Excellent hot-dip galvanized steel
  • This is a method for producing a cold-rolled steel sheet having excellent formability, panel shape, and dent resistance, which is characterized by having the following features.
  • This is a method for producing a hot-dip galvanized steel sheet having excellent formability, panel shape, and dent resistance, characterized by having the following features.
  • the cold-rolled steel sheet according to the present invention has a content of C: 0.004 to 0.015%, Si: 0.01 to 0.2%, and Mn: 0. 1 to 1.5%, P: 0.01 to 0.07%, S: 0.005 to 0.015%, so do A1: 0.01 to 0. 0 8%, N ⁇ 0.005%, and Nb: 0.02 to 0.12%.
  • the cold-rolled steel sheet according to the present invention is characterized in that the cold-rolled steel sheet further contains ⁇ : 0.0001 to 0.0002% by weight. This is a cold-rolled steel sheet excellent in panel surface shape and dent resistance described in (1).
  • the hot-dip galvanized steel sheet of the present invention is obtained by subjecting the cold-rolled steel sheet according to (6) or (7) to hot-dip galvanizing, and has excellent panel surface shape and dent resistance. It is a hot-dip galvanized steel sheet 0
  • This is a method for producing a cold-rolled steel sheet having excellent panel surface shape and dent resistance, which is characterized by having the following features.
  • This is a method for producing a hot-dip galvanized steel sheet with excellent panel surface shape and dent resistance, characterized by having the following features.
  • FIGS.1A and 1B are diagrams showing a relationship between El, r values and (NbX12) / (CX93) according to the first embodiment of the present invention.
  • FIG. 2 shows a panel dent resistance and a dent resistance according to the first embodiment of the present invention.
  • Fig. 3 shows P0.1 (2%, 4%, and 8% strain dent load resistance) and ((2% panel springback)) according to the first embodiment of the present invention. on sigma Z monument 0 9, e ⁇ (£) and illustrates the effect of component,
  • FIG. 4 shows P 0.1 (2%, 4%, and 8% strain dent load resistance of a panel subjected to strain) and 5 (2% panel spring knock amount) according to the first embodiment of the present invention.
  • FIG. 5 shows the results of the first embodiment of the present invention: ⁇ 0.1 (2%, 4%, 8% strain-resistant panel dent load) and ⁇ 5 (2% panel springback).
  • FIG. 6 is a diagram showing the effects of the finishing temperature and the winding temperature on ⁇ 0.1, 5, and W ca (filtering center line average waviness) of the 2% strain imparting panel according to the first embodiment of the present invention.
  • FIG. 7 is an explanatory diagram of an experiment for evaluating dent resistance and shape according to the second embodiment of the present invention.
  • FIG. 8 shows P0.1 (2% to 8% strain-resistant panel dent load resistance) and (5 (2% panel springback amount) according to the second embodiment of the present invention.
  • FIG. 9 shows the relationship between 0.1 (dent load resistance of a panel subjected to 2% to 8% strain) and ⁇ 5 (2% panel springback amount) according to the second embodiment of the present invention. And 0 2 , e X ⁇ ( ⁇ ) And a diagram showing the effect of the components,
  • FIG. 10 shows the relationship between P 0.1 (the dent load resistance of a panel subjected to 2% to 8% strain) and ((2% panel springback amount) according to the second embodiment of the present invention. shed 0., e X p ( ⁇ ) and illustrates the effect of component,
  • FIG. 11 shows the effects of the finishing temperature and the winding temperature on ⁇ 0.1, 5, and W ca (filtering center line average waviness) of the 2% strain imparting panel according to the second embodiment of the present invention.
  • FIG. 12 is a diagram showing the effect of storage time on ⁇ YP e 1 (the amount of recovery of ⁇ 61 when stored at 25 ° after temper rolling) according to Example 3 of the present invention.
  • the present inventors have obtained a cold-rolled steel sheet, a hot-dip galvanized steel sheet and a method for producing the same, which are excellent in steel sheet surface properties, room-temperature aging resistance and panel dent resistance required for a steel sheet for automobile outer panels. To this end, we conducted intensive research.
  • Panel dent resistance can be improved by designing the material with the steel in place, and good surface properties and room temperature aging resistance can be imparted to the steel sheet by intentionally suppressing the BH property. Heading, stable production of cold-rolled steel sheets and hot-dip galvanized steel sheets with a tensile strength of 34 OMPa or more, with excellent panel surface shape and dent resistance. Technology was invented.
  • the carbide formed as Nb affects the work hardening in the low strain range during panel forming, and contributes to the improvement of dent resistance. This effect is not obtained with C-force ⁇ 0.005%. If the content exceeds 0.015%, the panel dent resistance is improved, but the panel shape is deteriorated. For this reason, the C content is in the range of 0.05 to 0.015%.
  • Si is an effective additive element for strengthening steel, but if it is less than 0.01%, solid solution strengthening ability cannot be obtained. On the other hand, when the content exceeds 0.2%, not only the surface properties of the steel sheet are deteriorated, but also a spot-like surface defect is generated after the fusion plating. For this reason, the Si amount is in the range of 0.01 to 0.2%.
  • Mn is an element that precipitates and fixes S and suppresses deterioration of hot ductility. Also, it needs to be added because it is effective for strengthening steel. If it is less than 0.2%, hot brittleness is caused, which not only causes a problem in yield, but also fails to provide the strength characteristic of the present invention. Furthermore, Regarding the improvement of the workability intended in the present invention, the addition of Mn is indispensable for controlling the form of MnS during hot rolling. When the added amount of Mn is 0.2% or more, it can control the effect of inhibiting the grain growth due to the generation of fine MnS due to solid solution monoprecipitation during hot rolling. A more preferable Mn content for controlling the form during hot rolling of MnS is 0, 45% or more. Also, if the addition exceeds 1.5%, the hardness of the base steel sheet and the panel shape are deteriorated. Therefore, the lower limit of the Mn content is 0.2% and the upper limit is 1.5%.
  • P is the element with the highest solid solution strengthening ability of steel, and requires a content of at least 0.01%. If the content is less than 0.01%, the strengthening ability is small, and if the content exceeds 0.07%, not only the ductility is deteriorated, but also the alloying process in the continuous hot-dip galvanizing process. The result is bad. For this reason, the P content is in the range of 0.01 to 0.07%.
  • the steel causes hot brittleness, so the upper limit is 0.015%. If the S force is less than 0.006%, the peelability of the scale during hot rolling becomes poor, and the tendency of surface defects to occur becomes remarkable. Therefore, the lower limit is made 0.06%. Therefore, the S content is in the range of 0.06 to 0.015%.
  • a 1 is added for deoxidation of steel and for fixing N. If the A 1 content is less than 0.01%, it is not sufficient for deoxidation and fixation of N, and excessive addition exceeding 0.08% causes deterioration of the surface properties. Therefore, the upper and lower limits are 0.08% and 0.01%, respectively.
  • N is fixed as A 1 N. However, if the N content exceeds 0.004%, the moldability intended in the present invention cannot be obtained, so that the content is set to 0.004% or less.
  • 0 is a harmful element that adversely affects the growth of steel grain through the formation of oxide-based inclusions. If 0 exceeds 0.003%, the grain growth during annealing is deteriorated, and the formability and panel shape intended in the present invention cannot be obtained, so the content is set to 0.003% or less. . In addition, in order to set 0 to 0.003% or less in the component system characterized by the present invention, in addition to the above-mentioned appropriate control of so 1.A 1, 0 peak after the refining outside the furnace is performed. This is achieved only under optimal manufacturing conditions such as control of the pump.
  • N b combines with C to form fine carbides.
  • This carbide affects the work hardening behavior during panel forming and contributes to improving the dent resistance of the panel. If less than 0.04% is added, this effect cannot be obtained. On the other hand, if the addition amount exceeds 0.23%, the dent resistance is improved, but on the other hand, the panel shape such as spring back and surface distortion is deteriorated. For this reason, the Nb addition amount is set in the range of 0.04 to 0.23%. (Nbxi2) / (CX93): 1.0 to 3.0
  • (Nbx12) / (Cx93) is an essential requirement that should be controlled in order to enhance the formability in the present invention. If this value is less than 1.0, the fixation of C becomes insufficient, and the high r value and high ductility intended by the present invention cannot be obtained. On the other hand, if this value exceeds 3.0, on the contrary, ductility decreases due to an increase in the amount of solute Nb, and the moldability intended by the present invention cannot be obtained. Therefore, the lower and upper limits of (Nbxl2) / (CX93) are set to 1.0 and 3.0, respectively.
  • Figures 1A and 1B show the relationship between elongation (El), r-value and (NbX12) / (Cx93).
  • B in the following range in addition to the above steel composition.
  • the grain boundaries are strengthened, and the fines are refined.
  • the former improves the secondary work brittleness resistance, and the latter improves the dent resistance along with securing the absolute value of the material yield strength.
  • both effects cannot be obtained by adding less than 0.001%.
  • the content exceeds 0.02%, the panel shape is deteriorated due to a high yield point. For this reason, the amount of B added is in the range of 0.001 to 0.02%.
  • the true strain ⁇ is 0.002 to 0.096. (However, excluding 0.02), the ratio of the flow stress obtained in the tensile test to the 0.2% proof stress Q2 (ZCT Q2 ) is exp ( ⁇ ) X (5. 2 9 xe ⁇ ⁇ ( ⁇ ) — 4.19) to exp ( ⁇ ) x (5.64 xe ⁇ ⁇ ( ⁇ )-4.49).
  • the upper and lower limits of Z and Q 2 are defined as exp ( ⁇ ) x (5.64 xexp ( ⁇ )-4.49) and exp ( ⁇ ) x (5.29 xexp ( ⁇ ) — 4.19)
  • a steel sheet having such characteristics can be manufactured by the following manufacturing method.
  • the steel of the component (1) is melted.
  • the smelting method is generally the converter method, but the electric furnace method may be used.
  • this slab is heated immediately after the slab is produced or once cooled, and then subjected to hot rolling.
  • the finishing temperature is lower than (A r 3 — 100) ° C, 2% P 0.1 (the dent load resistance of the panel with 2% strain applied) is 1%.
  • As low as 40 to 150 N improvement in panel dent resistance cannot be obtained.
  • the finishing temperature is set to (A r 3-100 ° C) or more, and the winding temperature is set to a range of 500 ° C to 700 ° C.
  • the hot-rolled steel strip is pickled, cold-rolled, continuously annealed or continuously annealed, and then subjected to a hot-dip galvanizing treatment.
  • the cold rolling reduction is preferably 70% or more.
  • the annealing temperature is desirably in the recrystallization temperature range of the single phase of the fly.
  • the hot-dip galvanizing treatment but also the surface treatment such as zinc phosphate treatment and electro-zinc plating on the steel sheet obtained by continuous annealing, Does not occur.
  • the carbide formed as Nb or Ti affects the work hardening in the low strain region during panel forming and contributes to the improvement of dent resistance. This effect cannot be obtained if C is less than 0.004%. On the other hand, when the content exceeds 0.015%, the panel dent resistance is improved, but the panel shape is deteriorated. Therefore, the C content is in the range of 0.004 to 0.015%.
  • Si is an effective additive element for strengthening steel, but if it is less than 0.01%, solid solution strengthening ability cannot be obtained. On the other hand, when the content exceeds 0.2%, not only the surface properties of the steel sheet are deteriorated, but also a spot-like surface defect is generated after the fusion plating. For this reason, the Si amount is in the range of 0.01 to 0.2%.
  • Mn is an element that precipitates and fixes S and suppresses deterioration of hot ductility. Also, it needs to be added because it is effective for strengthening steel. 0. Less than 1% causes hot embrittlement. Further, if the addition exceeds 1.5%, the steel sheet becomes harder and the panel shape deteriorates. Therefore, the lower limit of the Mn content is 0.1% and the upper limit is 1.5%.
  • P is the element with the highest solid solution strengthening ability of steel, and requires a content of 0.01% or more. If the content is less than 0.01%, the strengthening ability is small, and if the content exceeds 0.07%, the ductility is deteriorated, and the alloying process in the continuous hot-dip galvanizing process. Occasionally it causes bad plating. For this reason, the P content is in the range of 0.01 to 0.07%.
  • the upper limit is 0.015%.
  • the content is less than 0.05%, the cost of hot metal desulfurization treatment and molten steel degassing treatment is reduced. For this reason, the S content is in the range of 0.05 to 0.05%.
  • a 1 is added to deoxidize steel. If it is less than 0.01%, it is insufficient for deoxidation, and if it exceeds 0.08%, the surface properties deteriorate. Therefore, the upper and lower limits are 0.08% and 0.01%, respectively.
  • N is fixed as TiN. However, if the content exceeds 0.005%, the aging resistance at room temperature deteriorates. % Or less.
  • N b combines with C to form fine carbides.
  • the carbide affects the work hardening behavior during panel molding and contributes to the improvement of panel dent resistance. If less than 0.02%, the effect cannot be obtained. If the content exceeds 0.12%, the dent resistance is improved, but the panel shape such as spring back and surface distortion is deteriorated. For this reason, the Nb addition amount is in the range of 0.02 to 0.12%.
  • Ti forms fine carbides like Nb. This carbide greatly contributes to improving the dent resistance of the molded panel. However, if the addition is less than 0.03%, the effect is small, and if the addition exceeds 0.1%, the shape of the panel is deteriorated and the molten zinc plating property is deteriorated. Therefore, the upper and lower limits of the added amount of Ti are 0.1% and 0.03%, respectively.
  • B may be contained in the following range according to the purpose of improving the secondary work brittleness resistance and the dent resistance.
  • the grain boundaries are strengthened and the fines are refined.
  • the former improves the secondary work brittleness resistance, and the latter improves the dent resistance along with securing the absolute value of the material yield strength.
  • both effects cannot be obtained by adding less than 0.001%.
  • the content exceeds 0.02%, the panel shape is deteriorated due to a higher yield point. For this reason, the amount of B added is in the range of 0.001 to 0.002%.
  • the true strain ⁇ is 0.002 to 0.096. (where 0. 0 0 2 such not included) in the region of the flow stress ⁇ obtained by a tensile test 0. the ratio of 2% yield strength beauty 0 "(beauty beauty 0 2) exp (epsilon) x (5 29 xexp ( ⁇ )-4.19) ⁇ exp ( ⁇ ) x (5.6 9
  • the dent load resistance is 2% P 0.1, 4% 0.1, and 8% P 0.1 (each 2%). , 4 and 8% strain, molded into the model panel shown in Fig. 1, heat-treated at 170 ° C for 20 minutes, and measured the load to give a residual dent of 0.1 mm).
  • the springback 5 (measured on a panel with a molding strain of 2%) becomes as large as 7 to 11%, while the shape is high at 60 to 210N, so the shape during panel molding is not favorable. If the upper limit is exceeded, the springback will be as small as 1 to 5%, but the dent load resistance will be as low as 140 to 165N, which means that improvement in dent resistance cannot be expected.
  • a steel sheet having such characteristics can be manufactured by the following manufacturing method.
  • the steel of the component (1) is melted.
  • the smelting method is generally the converter method, but the electric furnace method may be used.
  • the slab is subjected to hot rolling immediately after the production, or after the cooled slab is heated to 150 ° C. or more.
  • the hot-rolled steel strip is pickled, cold-rolled, continuously annealed or continuously annealed, and then subjected to a hot-dip galvanizing treatment.
  • the cold rolling reduction is preferably 70% or more.
  • Annealing is desirably performed at a temperature of 930 ° C or lower and in the recrystallization temperature range of a single phase of fluoride.
  • the hot-dip galvanizing treatment not only the hot-dip galvanizing treatment, but also the surface treatment such as zinc phosphate treatment and electro-zinc plating applied to the steel sheet obtained by continuous annealing, No problem.
  • the dent resistance is determined by the load P 0, 1 that gives a residual dent of 0.1 mm (hereinafter 2% P 0.1 and 4% P 0. 1, 8% P 0.1).
  • the panel shape was determined to be 5 for the springback amount and the average waviness of the filtering center line W c a
  • Comparative steels No. 8 and No. 9 have a high 2% BH force of 33 MPa to 42 MPa, and ⁇ YP61 has a 0.9% to 2.2%. Absent.
  • the dent load P 0.1 of 2% to 8% strain is as high as 165 to 193N and the dent resistance is good, but the El and r values are low and 5 and Wca. Is large, so moldability and shape are not good. Since the comparative steel No.
  • Comparative steel No. 11 has a high ⁇ 0.2 force of 26.5 MPa to 270 MPa, and has good dent resistance. However, since S and Wca are large, the panel shape is poor. El and r values are low. Comparative steel Nos. 12 and 13 have high r-values of 2.02 to 2.20, but low E1s of 35.8% to 36.8%. In addition, the dent resistance is good with a high power of 0.2 MPa to 25 OMPa, and the dent resistance is good, but the panel shape is not preferable because of a large 5 and Wca. Comparative steel N 0.
  • a steel having the composition of the steel No. 2 of the present invention shown in Table 1 was melted and manufactured in a laboratory to produce a slab having a thickness of 5 Omm. After slab-rolling the obtained slab to a thickness of 25 mm, it was heated in the air at 125 ° C for 1 hour, and subsequently hot-rolled to a sheet thickness of 2.8 mm. The finishing temperature and the winding temperature of the hot rolling were respectively changed in the range of 770 ° C to 930 ° C; and 450 ° C to 750 ° C. After pickling this hot-rolled sheet, it was cold-rolled to a sheet thickness of 0.75 mm, and then soaked at 825 ° C for 90 seconds, followed by temper rolling at an elongation of 1.2%. gave.
  • N 0.l to No. 3 has a finishing temperature of less than (A r 3—100) ° C, and 2% to 8% P 0.1 has 1339N to 1559N. Since it is low and has a high W ca force of 0.35 m to 0.40 m, the dent resistance and shape are not good.
  • the r value is as low as 1.69; L.77.
  • No. 7 and No. 12 have winding temperatures of less than 500 ° C, and 0.2 are high, 24 MPa and 248 MPa, respectively. Is good, but the S force is as large as 8% and the W ca force is as large as 0.30 m, so the panel shape is inferior.
  • the hot-rolled sheet is pickled and cold-rolled to a thickness of 0.75 mm, after continuous annealing at 850 ° C for 90 seconds or after annealing at 850 ° C for 90 seconds.
  • a zinc plating process was performed at 460 ° C, and an alloying process was performed at 500 ° C.
  • the annealed sheet or the hot-dip steel sheet was subjected to a 1.0% temper rolling to produce an experimental sample. Using this sample, tensile test (JIS No.
  • Table 5 shows the measurement and evaluation results.
  • the steels of the present invention No. 1 to 15 are within the range of the components of the present invention, the 2% BH content is 0 to 26 MPa, and the AYPel is 0% for all.
  • 2% P 0.1, 4% P 0.1, 8% P 0.1 is a comparative steel with C content of 0.025% and 2% BH content of 36 to 38MPa Compared with 1.6, it is higher, 150-180 N, 160-192 N, 175-208 N, and the panel dent resistance is good.
  • the panel shape is preferable.
  • 16 to 29 are outside the range of the present invention, and 2% P 0.1, 4% P 0.1, 8% P 0.1 are 14 0 to 95 N, 1 5 1 ⁇ 2 0 2 N, 16 0 ⁇ 2 13 N
  • the properties are good.
  • the 2% BH is 33 to 45 MPa, and the value YP e 1 ⁇ 0.2% W ca > 0.2 ⁇ m.
  • the aging resistance at normal temperature and the panel shape are deteriorated as compared with the examples of the present invention.
  • panel shape is poor because ⁇ 7%.
  • Table 6 shows the results of evaluation of the dent resistance (3% level panels of 2%, 4%, and 8%) and the shape (only 2% strain panel) of the panel (Example of the present invention: No. 4 ⁇ 7, 9 ⁇ 12, 15 ⁇ 18, 20, 21, 27 ⁇ 29, 32 ⁇ 34, 36 ⁇ 39, Comparative example: No. 1 ⁇ 3, 8, 13, 14, 19, 22 to 26, 30, 31, 35, 40) o
  • Comparative Example N 0. 1 ⁇ 3, N o 2 3 ⁇ 2 6 is finishing temperature is out of range the present invention - for (A r 3 1 0 0) is less than ° C, 2% ⁇ 8% P 0 1 is 140 to 158 N, 140 to 165 N, W ca is 0.3 to 0.43 m, 0.3 to 0.59 m, and is good. No excellent panel dent resistance and shape are obtained. In Comparative Examples Nos.
  • the winding temperature was higher than 700 ° C., which is outside the range of the present invention. Are all in the range of 144 N to 166 N, and the dent resistance is not good.
  • the W ca force was 0.33 to 0.42 / m, and the panel shape was poor.
  • Examples Nos. 4 to 7, 9 to 12, 15 to 18, 18, 20 to 21, 27 to 29, 32 to 34, and 36 to 39 of the present invention have finishing temperatures and Since the winding temperature is within the range of the present invention, 2 to 8% P 0.1 is in the range of 1531 to 188N, and the panel dent resistance is good. In each of the examples of the present invention, 5 ⁇ 5% and W ca ⁇ 0.2 m, and the shape is preferable.
  • the panel dent resistance, surface shape, and room temperature aging resistance required for a steel sheet for automobile outer panels are satisfied. It is possible to stably produce cold-rolled steel sheets and hot-dip zinc-coated steel sheets having a tensile strength of 340 MPa or more. Therefore, the utility value of the present invention in the steel industry and the automobile industry is large.

Abstract

laminée à froid possédant d'excellentes caractéristiques d'aptitude au moulage et de formabilité en panneaux ainsi qu'une bonne résistance à la constriction. La composition d'acier comprend 0,005-0,015 % en poids de C; 0,01-0,2 % en poids de Si; 0,2-1,5 % en poids de Mn; 0,01-0,07 % en poids de P; 0,006-0,015 % en poids de S; 0,01-0,08 % en poids de sol. Al; pas moins de 0,004 % en poids de N; pas moins de 0,003 % en poids de O; 0,04-0,23 % en poids de Nb, où 1,0 ≤ (Nb x 12)/(C x 93) ≤ 3,0; le reste est constitué sensiblement de Fe et d'impuretés inévitables. Le tout répond à l'équation suivante: exp(ε) x (5,29 x exp(ε) - 4,19) ≤ σ/σ0,2 ≤ exp(ε) x (5,64 x exp(ε) - 4,19) dans laquelle 0,002 < ε≤ 0,096; ε est une déformation rationnelle; σ0,2 est la limite d'élasticité conventionnelle 0,2 %; et σ est la limite d'élasticité conventionnelle par rapport à ε.
PCT/JP1998/004283 1998-04-27 1998-09-24 Plaque d'acier laminee a froid possedant d'excellentes caracteristiques d'aptitude au moulage et de formabilite en panneaux, une bonne resistance a la constriction, plaque d'acier a placage en zinc moule et procede de fabrication de ces plaques WO1999055927A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
BR9810485-3A BR9810485A (pt) 1998-04-27 1998-09-24 Chapa de aço laminada a frio e chapa de aço galvanizado, excelentes em conformabilidade, retenção de forma de painel e resistência de entalhe e processo de fabricação das mesmas
DE69840595T DE69840595D1 (de) 1998-04-27 1998-09-24 Kaltgewalzte stahlplatte exzellenter formbarkeit, flachförmigen eigenschaften und eindellwiderstand, feuerverzinkte stahlplatte und verfahren zur deren herstellung
US09/446,708 US6524726B1 (en) 1998-04-27 1998-09-24 Cold-rolled steel sheet and galvanized steel sheet, which are excellent in formability, panel shapeability, and dent-resistance, and method of manufacturing the same
EP98944222A EP1002884B1 (fr) 1998-04-27 1998-09-24 Plaque d'acier laminee a froid possedant d'excellentes caracteristiques d'aptitude au moulage et de formabilite en panneaux, une bonne resistance a la constriction, plaque d'acier a placage en zinc moule et procede de fabrication de ces plaques

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP11678898A JP4177478B2 (ja) 1998-04-27 1998-04-27 成形性、パネル形状性、耐デント性に優れた冷延鋼板、溶融亜鉛めっき鋼板及びそれらの製造方法
JP10/116788 1998-04-27

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WO1999055927A1 true WO1999055927A1 (fr) 1999-11-04

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JP3985523B2 (ja) * 2000-04-24 2007-10-03 Ｊｆｅスチール株式会社 継手部疲労特性に優れた直線型形鋼およびその製造方法
CA2379698C (fr) * 2000-05-26 2009-02-17 Kawasaki Steel Corporation Tole mince en acier lamine a froid et tole mince en acier galvanise presentant une trempabilite au vieillissement des contraintes
US20030015263A1 (en) 2000-05-26 2003-01-23 Chikara Kami Cold rolled steel sheet and galvanized steel sheet having strain aging hardening property and method for producing the same
WO2001098552A1 (fr) * 2000-06-20 2001-12-27 Nkk Corporation Feuille en acier mince et procede de production
JP4513434B2 (ja) * 2004-07-09 2010-07-28 Ｊｆｅスチール株式会社 コイル内材質均一性に優れた高強度冷延鋼板およびその製造方法
KR101042434B1 (ko) * 2007-10-29 2011-06-16 현대제철 주식회사 냉연강판 및 그의 제조방법
JP5056863B2 (ja) * 2010-01-15 2012-10-24 Ｊｆｅスチール株式会社 冷延鋼板およびその製造方法
CA3033685A1 (fr) 2016-09-20 2018-03-29 Thyssenkrupp Steel Europe Ag Procede de production de produits plats en acier et produit plat en acier
CN109844158B (zh) * 2016-10-17 2021-09-07 塔塔钢铁艾默伊登有限责任公司 用于涂漆零件的钢基底
DE102017103308A1 (de) * 2017-02-17 2018-08-23 Voestalpine Stahl Gmbh Verfahren zum Herstellen von Stahlblechen
KR102322713B1 (ko) * 2019-12-19 2021-11-04 주식회사 포스코 내열성과 성형성이 우수한 냉연강판 및 그 제조방법
US20230050487A1 (en) * 2020-01-24 2023-02-16 Nippon Steel Corporation Panel
KR102556444B1 (ko) * 2020-12-29 2023-07-18 현대제철 주식회사 우수한 내덴트 특성을 가지는 내덴트성 냉연강판, 내덴트성 도금강판 및 그 제조방법
CN117165845B (zh) * 2023-04-28 2024-04-16 鞍钢股份有限公司 新能源汽车用340MPa级合金化热镀锌板及其制备方法

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DE69840595D1 (de) 2009-04-09
EP1002884A4 (fr) 2006-04-05
EP1002884A1 (fr) 2000-05-24
EP2172575A1 (fr) 2010-04-07
KR20010014238A (ko) 2001-02-26
JPH11310849A (ja) 1999-11-09
CN1261408A (zh) 2000-07-26
EP1002884B1 (fr) 2009-02-25
CN1084797C (zh) 2002-05-15
KR100345012B1 (ko) 2002-07-20
CN1138016C (zh) 2004-02-11
BR9810485A (pt) 2000-09-12
JP4177478B2 (ja) 2008-11-05
CN1405352A (zh) 2003-03-26

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