EP1514951B1 - Tole d'acier lamine a froid a haute resistance et procede de fabrication - Google Patents
Tole d'acier lamine a froid a haute resistance et procede de fabrication Download PDFInfo
- Publication number
- EP1514951B1 EP1514951B1 EP03736017A EP03736017A EP1514951B1 EP 1514951 B1 EP1514951 B1 EP 1514951B1 EP 03736017 A EP03736017 A EP 03736017A EP 03736017 A EP03736017 A EP 03736017A EP 1514951 B1 EP1514951 B1 EP 1514951B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- steel sheet
- less
- phase
- rolled steel
- high strength
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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- 239000010960 cold rolled steel Substances 0.000 title claims description 31
- 238000004519 manufacturing process Methods 0.000 title claims description 16
- 229910000831 Steel Inorganic materials 0.000 claims description 65
- 239000010959 steel Substances 0.000 claims description 65
- 238000001816 cooling Methods 0.000 claims description 35
- 229910000734 martensite Inorganic materials 0.000 claims description 21
- 229910000859 α-Fe Inorganic materials 0.000 claims description 18
- 238000010438 heat treatment Methods 0.000 claims description 13
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 12
- 229910001566 austenite Inorganic materials 0.000 claims description 12
- 239000000203 mixture Substances 0.000 claims description 12
- 238000005098 hot rolling Methods 0.000 claims description 7
- 229910052742 iron Inorganic materials 0.000 claims description 6
- 238000005097 cold rolling Methods 0.000 claims description 5
- 229910052748 manganese Inorganic materials 0.000 claims description 4
- 239000012535 impurity Substances 0.000 claims description 3
- 229910052804 chromium Inorganic materials 0.000 claims description 2
- 229910052750 molybdenum Inorganic materials 0.000 claims description 2
- 229910052758 niobium Inorganic materials 0.000 claims description 2
- 229910052720 vanadium Inorganic materials 0.000 claims description 2
- 229910052726 zirconium Inorganic materials 0.000 claims description 2
- 238000000137 annealing Methods 0.000 description 16
- 230000000052 comparative effect Effects 0.000 description 11
- 238000005496 tempering Methods 0.000 description 10
- 238000000034 method Methods 0.000 description 8
- 229910001563 bainite Inorganic materials 0.000 description 6
- 230000002542 deteriorative effect Effects 0.000 description 6
- 238000005096 rolling process Methods 0.000 description 6
- 230000002708 enhancing effect Effects 0.000 description 5
- 238000010583 slow cooling Methods 0.000 description 5
- 230000009466 transformation Effects 0.000 description 5
- 238000005452 bending Methods 0.000 description 3
- 230000003247 decreasing effect Effects 0.000 description 3
- 229910001562 pearlite Inorganic materials 0.000 description 3
- 238000010791 quenching Methods 0.000 description 3
- 238000002791 soaking Methods 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 2
- 238000009749 continuous casting Methods 0.000 description 2
- 230000009977 dual effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000000171 quenching effect Effects 0.000 description 2
- 238000003303 reheating Methods 0.000 description 2
- 230000003014 reinforcing effect Effects 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000005279 austempering Methods 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 229910001567 cementite Inorganic materials 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 239000013585 weight reducing agent Substances 0.000 description 1
Classifications
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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
- C22C38/06—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
- C22C38/02—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
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/008—Martensite
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0236—Cold rolling
Definitions
- the present invention relates to a high strength cold-rolled steel sheet, favorable for use in a structural member of machine, particularly in a structural member of automobile, which has a tensile strength of 780MPa or more, and a manufacturing method thereof.
- stress-flangeability means a property resisting to generation of cracks on a blank end face of steel sheet when it is press-formed and is evaluated, based on a hole-expanding ratio measured by means of hole-expanding test defined by the Japan Iron and Steel Federation Standard: JFST 1001-1996.
- JP-B No. 7-59726 JP-A Nos. 2001-226741 , 10-60593 and 9-263838 , high strength cold-rolled steel sheets which have each aimed for improving stretch-flangeability by controlling structure through optimizing steel compositions and manufacturing conditions, and manufacturing methods thereof are disclosed. More specifically, for example, in JP-A No. 9-263838 , a cold-rolled steel sheet is slowly cooled from soaking temperature at the time of annealing to allow second phase to be uniformly dispersed in ferrite phase and, then, bainite phase is allowed to be uniformly dispersed in the ferrite phase as a main component by adjusting cooling rate and overaging temperature, thereby aiming for enhancing strength and improving stretch-flangeability.
- JP-A No. 2001-355044 a high strength cold-rolled steel sheet in which ferrite phase is allowed to have higher strength and from 2% to 20% of residual austenite phase is formed in the ferrite phase to aim for simultaneously achieving strength enhancement and stretch-flangeability improvement is disclosed.
- JP-A No. 11-350038 a method for producing a complex phase type high strength cold-rolled steel sheet which is excellent in ductility and stretch-flangeability and has a tensile strength of about 980MPa by controlling compositions and producing conditions is disclosed.
- JP-A No. 9-41040 a method for manufacturing a high strength cold-rolled steel sheet which is excellent in stretch-flangeability by subjecting a cold-rolled steel sheet to annealing in an ⁇ + ⁇ region, cooling the resultant steel sheet by holding it in a temperature range of from 650°C to temperature to stop pearlite transformation for 10 seconds or more and, then, cooling the cooled steel sheet by holding it in a temperature range of from temperature to stop pearlite transformation to 450°C for 5 seconds or less is disclosed.
- JP-B No. 58-55219 and Japanese Patent No. 2545316 a method for producing a high strength cold-rolled steel sheet by more strictly defining compositions and performing annealing under specified continuous annealing conditions is disclosed.
- JP-B No. 7-68583 a method for manufacturing a dual phase type high strength cold-rolled steel sheet which is excellent in mechanical characteristics, spot-weldability and phosphatability by specifying content of C, Si, and Mn, reheating conditions before hot rolling, soaking conditions, atmosphere and the like in continuous annealing after cold rolling is disclosed.
- JP-B No. 8-30212 a method for manufacturing a high strength cold-rolled steel sheet having high ductility and excellent bending property by allowing structure after hot rolling to be uniformly finer such that band structure is not generated therein and, then, allowing the resultant structure after continuous annealing to be that in which ferrite phase and martensite phase are uniformly distributed is disclosed.
- JP-B No. 5-57332 a method for producing a high strength cold-rolled steel sheet which has a yield ratio of 0.65% or less and is excellent in both surface property and bending property by heating steel containing Si and a comparatively large amount of Mn to austenite single phase zone which is higher than Ac3 transformation temperature and, then, allowing complex phase structure comprising ferrite phase and second phase such as martensite phase to be formed in a cooling step is disclosed.
- JP-B Nos. 1-35051 and 1-35052 a method for manufacturing a high strength cold-rolled steel sheet which is excellent in ductility by controlling heating temperature in continuous annealing, water-quenching start temperature, and overaging treatment temperature is disclosed.
- JP-B Nos. 7-74412 and 3-68927 a method for producing a high strength cold-rolled steel sheet which is excellent in bending property, deep drawability, and resistance to seasoned crack by allowing condensation of C to be low to thereby set austenite phase to be 5% or less by means of performing annealing in a high temperature range after cold rolling is disclosed.
- JP-B 7-59726 it is essential to perform overaging treatment at such a high temperature as 350°C or more and, in order to compensate decrease of tensile strength to be caused by such high temperature overaging treatment, a large amount of C which is a reinforcing element has been added (in steel Nos. 9, 10, and 13 according to the invention in Table 1, in order to have a tensile strength of 980MPa or more, 0.17% or more of C has been added.). For this reason, when the steel is spot-welded at the time of assembling an automobile, tenacity of spot-welded portion is deteriorated and, as a result, joint strength thereof is decreased. Further, since overaging treatment temperature is high, energy cost in production is increased, thereby deteriorating productivity.
- a hole-expanding ratio is as low as 56% (steel 9 or more, hole-expanding ratio is as low as 56% (steel according to the invention in Table 1), thereby allowing stretch-flangeability to be insufficient.
- JP-A No. 2001-226741 it is essential to perform austempering treatment after soaking in continuous annealing in order to generate bainite phase, but there is a problem in that consistent characteristics of steel sheet can not be obtained in this treatment.
- JP-A No. 2001-355044 since residual austenite phase is allowed to exist, it is essential to generate bainite phase, thereby decreasing strength.
- the tensile strength shown in an example is as low as from 600MPa to 800MPa, thereby being incapable of consistently obtaining a tensile strength of 780MPa or more.
- JP-A Nos. 9-41040 and 9-263838 since structure comprises ferrite phase and pearlite phase, or ferrite phase and bainite phase, tensile strength is as low as from 400MPa to 700MPa.
- JP-A No. 10-60593 JP-B Nos. 58-55219 and 7-68583 , and Japanese Patent No. 2545316 , tensile strength of from 400MPa to 700MPa can only be obtained.
- JP 10-147838 discloses a cold-rolled steel sheet with a tensile strength lower than 780 MPa and a martensite content of 5 to 30%.
- An object of the present invention is to provide a high strength cold-rolled steel sheet having an elongation of 18% or more, a hole-expanding ratio of 60% or more, and a tensile strength of 780MPa or more and a manufacturing method thereof
- This obj ect can be achieved by a high strength cold-rolled steel sheet comprising the features of claim 1.
- this high strength cold-rolled steel sheet can be realized by a method comprising the features of claim 2.
- the present inventors have studied on a steel sheet which, even though an amount of C is reduced, has a tensile strength of 780MPa or more and, further, excellent ductility in which an elongation is 18% or more, and excellent stretch-flangeability in which a hole-expanding ratio is 60% or more, and found that the steel sheet can be realized by a steel sheet consisting essentially of, in terms of percentages by mass, 0.04 to 0.10% C, 0.5 to 1.5% Si, 1.8 to 3% Mn, 0.02% or less P, 0.01% or less S, 0.01 to 0.1% Sol. Al, 0.005% or less N, and the balance being iron and inevitable impurities and having a structure substantially comprising ferrite phase and martensite phase. Only components of 0.04 to 0.07 % are within the scope of the appending claims.
- C is an important element for giving a great influence on tensile strength, and reinforcing martensite phase which is generated at quenching.
- an amount of C is less than 0.04%, a tensile strength of 780MPa or more can not be obtained, while, when it is over 0.10%, stretch-flangeability and spot-weldability are remarkably deteriorated. Accordingly, the amount of C is set to be 0.04 to 0.10%. Further, in order to obtain a tensile strength of from 780MPa to less than 980MPa without deteriorating stretch-flangeability or spot-weldability, it is preferable to set the amount of C to be 0.04% to less than 0.070%.
- Si is effective in enhancing ductility of dual phase type steel sheet comprising ferrite phase and martensite phase.
- an amount of Si is less than 0.5%, effectiveness thereof becomes insufficient, while, when it is over 1.5%, a large amount of Si oxide is formed on a surface of steel sheet in a hot rolling step, thereby generating surface defects.
- the amount of Si is set to be 0.5 to 1. 5%. Further, from the point of view of phosphatability, the amount of Si is desirably set to be 1.0% or less.
- Mn is an important element for suppressing generation of ferrite phase in a cooling step of continuous annealing.
- an amount of Mn is set to be 1.8 to 3%.
- the amount of Mn is desirably set to be 2.0 to 2.5%.
- Sol. Al Al is added for performing deoxidization of steel or precipitating N as AlN.
- an amount of Sol. Al is less than 0.01%, the deoxidization or the precipitation of AlN is not sufficiently performed, while, when it is over 0.1%, effectiveness thereof is saturated, thereby inviting a cost increase. Accordingly, the amount of Sol. Al is set to be 0.01 to 0.1%.
- N since N deteriorates formability of steel sheet, an amount of N is desirably as low as possible. However, when the amount thereof is reduced more than necessary, a refining cost is increased. Accordingly, the amount of N is set to be 0.005% or less such that it does not substantially deteriorate the formability.
- Structure of steel sheet substantially comprises two phases of: ferrite phase and martensite phase. Besides these two phases, bainite phase in which iron is a main constitutional element or austenite phase may not deteriorate effectiveness of the present invention, so long as it is contained in an amount of less than 2% in terms of volume fraction. Further, compounds containing iron such as cementite may be contained in the ferrite phase, the martensite phase or an interface between ferrite and martensite phases. Still further, compounds such as AlN and MnS may not impair the effectiveness of the present invention, so long as each of the composition elements or impurity elements is within the scope of the invention.
- volume fraction of martensite phase is 30 to 45%, in the range of from 780MPa to less than 980MPa of tensile strength, or when it is 45 to 60%, in the range of from 980MPa to 1180MPa of tensile strength, more excellent stretchflangeability can be obtained. Only a volume fraction of martensite phase from 30 to 45 % is within the scope of the appending claims
- a tempering treatment can appropriately be performed on the martensite phase.
- a slab having the aforementioned compositions is produced by continuous casting method or ingot making plus blooming method and, then, either after reheating or directly, the resultant slab is hot-rolled.
- a final rolling temperature (finishing temperature) at hot rolling is desirably from Ar3 transformation temperature to 870 DEG C, in order to allow structure to be finer to thereby enhance ductility or stretch-flangeability.
- the hot-rolled steel sheet is cooled and, then, coiled.
- a coiling temperature is desirably 620 DEG C or less for the purpose of enhancing ductility or stretch-flangeability.
- a cold-rolling reduction rate is desirably 55% or more for the purpose of enhancing ductility or stretch-flangeability by allowing structure to be finer.
- the cold-rolled steel sheet is annealed under conditions as described below in a continuous annealing furnace.
- a heating temperature is less than 750°C, a sufficient amount of austenite phase is not generated and, accordingly, high strength can not be aimed for, while, when it is over 870°C, transformation into austenite single phase occurs allowing structure to be coarse, thereby deteriorating ductility or stretch-flangeability. Further, when a heating time is less than 10 seconds, austenite phase is not sufficiently generated and, accordingly, high strength can not be aimed for.
- a cooling rate at this time is desirably set to be 20°C/sec in the range of from 550°C to 750°C depending on compositions such that a volume fraction of austenite phase can be adjusted to be from 30% to 45% or from 45% to 60%, namely, a volume fraction of martensite phase can ultimately be adjusted to be from 30% to 45% or from 45% to 60%.
- cooling terminal temperature is preferably set to be 100°C or less.
- the resultant steel sheet may be held at the cooling terminal temperature for from 5 minutes to 20 minutes or subjected to tempering treatment at from 150°C to 390°C for from 5 minutes to 20 minutes.
- tempering treatment By performing the tempering treatment, the martensite phase which has been generated at the rapid cooling is tempered, thereby enhancing ductility and stretch-flangeability.
- a tempering temperature is less than 150°C, or a tempering time is less than 5 minutes, such effect as described above can not sufficiently be obtained.
- the tempering temperature is over 390°C, or the tempering time is over 20 minutes, strength is remarkably decreased, thereby being sometimes incapable of obtaining a tensile strength of 780MPa or more.
- the obtained steel sheet is subjected to temper rolling at a reduction rate of from 0.1% to 0.7% to thereby eliminate yield elongation completely.
- the steel sheet according to the present invention can be electroplated, hot-dip galvanized or applied with solid lubricant.
- Steel Nos. 1 to 10 having respective compositions as shown in Table 1 were each cast into slab.
- the cast slab was reheated at 1250°C, hot-rolled at a finishing temperature of about 860°C, and slowly cooled at about 20°C/sec to produce a hot-rolled steel sheet having a thickness of 2.8mm by simulating coiling at 600°C for one hour.
- the hot-rolled steel sheet was cold-rolled to produce a cold-rolled steel sheet having a thickness of 1.2 mm and, then, the cold-rolled steel sheet was subj ected to heating treatment which simulated continuous annealing.
- the continuous annealing was performed under conditions that a temperature of the steel sheet was elevated at a heating rate of about 20°C/sec and, then, the steel sheet was soaked at 830°C for 300 seconds, slowly cooled down to 700°C at about 10°C/sec and, thereafter, rapidly cooled in jet-flowing water having a temperature of 20°C. A cooling rate of such rapid cooling was about 2000°C/sec. Finally, the steel sheet was subjected to tempering treatment at 300°C for 15 minutes, cooled and, then, subjected to temper rolling of 0.3% to produce steel sheet Nos. 1 to 10. Thereafter, in regard to the steel sheet Nos. 1 to 10, respective tensile characteristics and hole-expanding ratios ( ⁇ ) were measured.
- JIS Z 2201 JIS No. 5 test piece was obtained along each of a rolling direction and a direction at a right angle thereto and subjected to a test in accordance with JIS Z 2241 to determine yield strength (YP), tensile strength (TS), and elongation (El).
- each of steel sheet Nos. 2, 3, 9, and 10 which are examples according to the present invention satisfies the relations: TS ⁇ 780 MPa; El ⁇ 8%; and ⁇ 60%, and thus has high strength, and is excellent in ductility and stretch-flangeability.
- steel sheet No. 1 is low in TS, due to small amount of C; steel sheet No. 5 is remarkably low in ⁇ , due to large amount of C and small amount of Mn; steel sheet No. 6 is low in ⁇ , due to small amount of Si; steel sheet No. 7 is low in TS and ⁇ , due to small amount of Mn; and steel sheet No. 8 is low in El, due to large amount of Mn.
- Example 1 By using the slab of steel No. 2 as shown in Table 1, the steps up to cold rolling were performed under same conditions as in Example 1 and, then, continuous annealing and tempering treatment were performed under conditions as shown in Table 3. Finally, temper rolling of 0.3% was performed in the same manner as in Example 1 to produce steel sheet Nos. A to H. Thereafter, in regard to steel sheet Nos. A to H, the same tests as in Example 1 were conducted.
- each of steel sheet Nos. A, E, G, and H which are examples according to the present invention satisfies the relations: TS ⁇ 780 MPa; El ⁇ 18%; and ⁇ 60%, and thus has high strength, and is excellent in ductility and stretch-flangeability.
- each of steel sheet Nos. 1, 2, 3, 8, and 9 which are examples according to the present invention satisfies the relations: TS ⁇ 780 MPa; El ⁇ 18%; and ⁇ 60%, and thus has high strength, and is excellent in ductility and stretch-flangeability.
- steel sheet No. 4 is low in El and ⁇ , due to large amount of C
- steel sheet No. 5 is remarkably low in ⁇ , due to large amount of C and small amount of Mn
- steel sheet No. 6 is low in ⁇ , due to small amount of Si
- steel sheet No. 7 is low in El and ⁇ , due to large amount of Mn.
- Table 5 Steel No. Chemical compositions (mass%) Remark C Si Mn P S Sol.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Sheet Steel (AREA)
Claims (2)
- Tôle d'acier à haute résistance laminée à froid, consistant en, en termes de pourcentages en masse, 0,04 à 0,070%des, 0,5 à 1,5 % de Si, 1,8 à 3 % de Mn, 0,02 % ou moins de P, 0,01 % ou moins de S, 0,01 à 0,1 % de Sol. Al, 0,005 % ou moins de N, comprenant en outre optionnellement au moins un élément sélectionné dans le groupe constitué de : en termes de pourcentages en masse, 0,01 à 1,0 % de Cr, 0,01 à 0,5 % de Mo, 0,0001 à 0,0020 % de B, 0,001 à 0,05 % de Ti, 0,001 à 0,05 % de Nb, 0,001 à 0,05 % de V et 0,001 à 0,05 % de Zr et le reste étant du fer et des impuretés inévitables, ayant une structure consistant sensiblement en une phase de ferrite et en une phase de martensite, et ayant une résistance à la traction de 780 MPa à moins de 980 MPa, dans laquelle une fraction volumique de phase de martensite est de 30 % à 45 %.
- Procédé pour produire une tôle d'acier à haute résistance laminée à froid, comprenant les étapes consistant à :produire une tôle d'acier par laminage à chaud d'une brame d'acier consistant en compositions telles qu'exposées dans la revendication 1, suivi par un laminage à froid ;chauffer la tôle d'acier laminée à froid de 750 °C à 870 °C pendant 10 secondes ou plus ;refroidir la tôle d'acier chauffée jusqu'a de 550 °C à 750 °C ;refroidir la tôle d'acier chauffée à une vitesse de refroidissement de 20 °C/s ou moins à l'intérieur de la plage de températures allant de 550 °C à 750 °C de sorte qu'une fraction volumique de phase d'austénite est ajustée pour être comprise entre 30 % et 45 % ; etrefroidir la tôle d'acier refroidie jusqu'à 300 °C ou moins à une vitesse de refroidissement supérieure à 100 °C/s.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP08159197A EP2017363A3 (fr) | 2002-06-14 | 2003-06-04 | Plaque d'acier laminé à froid haute résistance et son procédé de fabrication |
Applications Claiming Priority (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2002173668 | 2002-06-14 | ||
JP2002173668A JP4265152B2 (ja) | 2002-06-14 | 2002-06-14 | 伸びおよび伸びフランジ性に優れた高張力冷延鋼板およびその製造方法 |
JP2002173669 | 2002-06-14 | ||
JP2002173669A JP4265153B2 (ja) | 2002-06-14 | 2002-06-14 | 伸びおよび伸びフランジ性に優れた高張力冷延鋼板およびその製造方法 |
PCT/JP2003/007062 WO2003106723A1 (fr) | 2002-06-14 | 2003-06-04 | Tole d'acier lamine a froid a haute resistance et procede de fabrication |
Related Child Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP08159197A Division EP2017363A3 (fr) | 2002-06-14 | 2003-06-04 | Plaque d'acier laminé à froid haute résistance et son procédé de fabrication |
EP08159197.6 Division-Into | 2008-06-27 |
Publications (3)
Publication Number | Publication Date |
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EP1514951A1 EP1514951A1 (fr) | 2005-03-16 |
EP1514951A4 EP1514951A4 (fr) | 2006-05-10 |
EP1514951B1 true EP1514951B1 (fr) | 2010-11-24 |
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Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
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EP03736017A Expired - Lifetime EP1514951B1 (fr) | 2002-06-14 | 2003-06-04 | Tole d'acier lamine a froid a haute resistance et procede de fabrication |
EP08159197A Withdrawn EP2017363A3 (fr) | 2002-06-14 | 2003-06-04 | Plaque d'acier laminé à froid haute résistance et son procédé de fabrication |
Family Applications After (1)
Application Number | Title | Priority Date | Filing Date |
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EP08159197A Withdrawn EP2017363A3 (fr) | 2002-06-14 | 2003-06-04 | Plaque d'acier laminé à froid haute résistance et son procédé de fabrication |
Country Status (4)
Country | Link |
---|---|
US (1) | US20040238082A1 (fr) |
EP (2) | EP1514951B1 (fr) |
DE (1) | DE60335106D1 (fr) |
WO (1) | WO2003106723A1 (fr) |
Families Citing this family (27)
Publication number | Priority date | Publication date | Assignee | Title |
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JP4530606B2 (ja) * | 2002-06-10 | 2010-08-25 | Jfeスチール株式会社 | スポット溶接性に優れた超高強度冷延鋼板の製造方法 |
US8337643B2 (en) | 2004-11-24 | 2012-12-25 | Nucor Corporation | Hot rolled dual phase steel sheet |
US7959747B2 (en) * | 2004-11-24 | 2011-06-14 | Nucor Corporation | Method of making cold rolled dual phase steel sheet |
US7442268B2 (en) * | 2004-11-24 | 2008-10-28 | Nucor Corporation | Method of manufacturing cold rolled dual-phase steel sheet |
JP4461112B2 (ja) * | 2006-03-28 | 2010-05-12 | 株式会社神戸製鋼所 | 加工性に優れた高強度鋼板 |
US11155902B2 (en) * | 2006-09-27 | 2021-10-26 | Nucor Corporation | High strength, hot dip coated, dual phase, steel sheet and method of manufacturing same |
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-
2003
- 2003-06-04 EP EP03736017A patent/EP1514951B1/fr not_active Expired - Lifetime
- 2003-06-04 DE DE60335106T patent/DE60335106D1/de not_active Expired - Lifetime
- 2003-06-04 US US10/485,780 patent/US20040238082A1/en not_active Abandoned
- 2003-06-04 EP EP08159197A patent/EP2017363A3/fr not_active Withdrawn
- 2003-06-04 WO PCT/JP2003/007062 patent/WO2003106723A1/fr active Application Filing
Also Published As
Publication number | Publication date |
---|---|
EP1514951A4 (fr) | 2006-05-10 |
WO2003106723A1 (fr) | 2003-12-24 |
US20040238082A1 (en) | 2004-12-02 |
EP2017363A2 (fr) | 2009-01-21 |
DE60335106D1 (de) | 2011-01-05 |
EP2017363A3 (fr) | 2009-08-05 |
EP1514951A1 (fr) | 2005-03-16 |
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