EP2064360B1 - Steel sheet for the manufacture of light structures and manufacturing process of this sheet - Google Patents
Steel sheet for the manufacture of light structures and manufacturing process of this sheet Download PDFInfo
- Publication number
- EP2064360B1 EP2064360B1 EP07823448.1A EP07823448A EP2064360B1 EP 2064360 B1 EP2064360 B1 EP 2064360B1 EP 07823448 A EP07823448 A EP 07823448A EP 2064360 B1 EP2064360 B1 EP 2064360B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- steel sheet
- steel
- sheet according
- rolling
- tib
- 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.)
- Active
Links
- 229910000831 Steel Inorganic materials 0.000 title claims description 135
- 239000010959 steel Substances 0.000 title claims description 135
- 238000004519 manufacturing process Methods 0.000 title claims description 22
- 239000002244 precipitate Substances 0.000 claims description 66
- 239000010936 titanium Substances 0.000 claims description 64
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 49
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 41
- 230000005496 eutectics Effects 0.000 claims description 39
- 229910052719 titanium Inorganic materials 0.000 claims description 37
- 239000000203 mixture Substances 0.000 claims description 35
- 229910052796 boron Inorganic materials 0.000 claims description 23
- 238000001816 cooling Methods 0.000 claims description 20
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 19
- 238000005266 casting Methods 0.000 claims description 19
- 238000005096 rolling process Methods 0.000 claims description 19
- 239000011265 semifinished product Substances 0.000 claims description 19
- 238000000034 method Methods 0.000 claims description 18
- 238000005098 hot rolling Methods 0.000 claims description 15
- 238000007711 solidification Methods 0.000 claims description 15
- 230000008023 solidification Effects 0.000 claims description 15
- 229910033181 TiB2 Inorganic materials 0.000 claims description 14
- 238000000137 annealing Methods 0.000 claims description 14
- 230000008569 process Effects 0.000 claims description 14
- QYEXBYZXHDUPRC-UHFFFAOYSA-N B#[Ti]#B Chemical compound B#[Ti]#B QYEXBYZXHDUPRC-UHFFFAOYSA-N 0.000 claims description 12
- 238000005097 cold rolling Methods 0.000 claims description 10
- 229910052804 chromium Inorganic materials 0.000 claims description 9
- 229910052710 silicon Inorganic materials 0.000 claims description 8
- 239000012535 impurity Substances 0.000 claims description 6
- 229910052742 iron Inorganic materials 0.000 claims description 6
- 229910052750 molybdenum Inorganic materials 0.000 claims description 6
- 229910052758 niobium Inorganic materials 0.000 claims description 5
- 229910052720 vanadium Inorganic materials 0.000 claims description 5
- 239000000126 substance Substances 0.000 claims description 4
- 229910052717 sulfur Inorganic materials 0.000 claims description 4
- 229910052698 phosphorus Inorganic materials 0.000 claims description 3
- 230000002787 reinforcement Effects 0.000 claims description 2
- 238000001556 precipitation Methods 0.000 description 37
- 239000011159 matrix material Substances 0.000 description 19
- 229910052799 carbon Inorganic materials 0.000 description 17
- 239000002245 particle Substances 0.000 description 17
- 238000003466 welding Methods 0.000 description 16
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 11
- 238000007792 addition Methods 0.000 description 11
- 239000000919 ceramic Substances 0.000 description 10
- 239000011651 chromium Substances 0.000 description 10
- 241001080024 Telles Species 0.000 description 8
- 230000015572 biosynthetic process Effects 0.000 description 8
- 229910001338 liquidmetal Inorganic materials 0.000 description 7
- 239000011572 manganese Substances 0.000 description 6
- 239000000843 powder Substances 0.000 description 6
- 239000000047 product Substances 0.000 description 6
- 238000001953 recrystallisation Methods 0.000 description 6
- 230000007423 decrease Effects 0.000 description 5
- 229910052748 manganese Inorganic materials 0.000 description 5
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 5
- 239000012071 phase Substances 0.000 description 5
- 238000003303 reheating Methods 0.000 description 5
- 230000035882 stress Effects 0.000 description 5
- 230000009466 transformation Effects 0.000 description 5
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 4
- 229910052782 aluminium Inorganic materials 0.000 description 4
- 239000010953 base metal Substances 0.000 description 4
- 230000035784 germination Effects 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 239000010955 niobium Substances 0.000 description 4
- 238000007493 shaping process Methods 0.000 description 4
- 238000005245 sintering Methods 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 238000004804 winding Methods 0.000 description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- 230000000295 complement effect Effects 0.000 description 3
- 238000009749 continuous casting Methods 0.000 description 3
- 238000005336 cracking Methods 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000002349 favourable effect Effects 0.000 description 3
- 229910000734 martensite Inorganic materials 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 229910052759 nickel Inorganic materials 0.000 description 3
- 239000010703 silicon Substances 0.000 description 3
- 239000006104 solid solution Substances 0.000 description 3
- 238000011282 treatment Methods 0.000 description 3
- 229910001021 Ferroalloy Inorganic materials 0.000 description 2
- 229910017108 Fe—Fe Inorganic materials 0.000 description 2
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 2
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- 238000005054 agglomeration Methods 0.000 description 2
- 230000002776 aggregation Effects 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 238000005056 compaction Methods 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 238000011109 contamination Methods 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 239000007970 homogeneous dispersion Substances 0.000 description 2
- 150000001247 metal acetylides Chemical class 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000011733 molybdenum Substances 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 239000007790 solid phase Substances 0.000 description 2
- 239000011593 sulfur Substances 0.000 description 2
- 229910000885 Dual-phase steel Inorganic materials 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 240000008042 Zea mays Species 0.000 description 1
- 230000001464 adherent effect Effects 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 230000003416 augmentation Effects 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000001413 cellular effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000003776 cleavage reaction Methods 0.000 description 1
- 238000000975 co-precipitation Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000010960 cold rolled steel Substances 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 238000010908 decantation Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000006355 external stress Effects 0.000 description 1
- 238000005188 flotation Methods 0.000 description 1
- 238000005246 galvanizing Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 229910001234 light alloy Inorganic materials 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- VCTOKJRTAUILIH-UHFFFAOYSA-N manganese(2+);sulfide Chemical class [S-2].[Mn+2] VCTOKJRTAUILIH-UHFFFAOYSA-N 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 238000000399 optical microscopy Methods 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 238000004663 powder metallurgy Methods 0.000 description 1
- 230000037452 priming Effects 0.000 description 1
- 238000001812 pycnometry Methods 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 238000001226 reprecipitation Methods 0.000 description 1
- 238000004626 scanning electron microscopy Methods 0.000 description 1
- 230000007017 scission Effects 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 238000005482 strain hardening Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
- 239000013585 weight reducing agent Substances 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
Definitions
- the invention relates to the manufacture of steel sheets or structural parts simultaneously combining a high modulus of elasticity E, a reduced density and a high strength.
- JP2005154826 describes a high-rigidity steel that has a high Young's modulus (high modulus of elasticity E) and can be manufactured by the ingoting method, and relates to steel that can especially improve the structural components of machine
- the invention aims to solve the above problems, in particular the large scale and economical availability of steels with increased modulus of elasticity by the presence of TiB 2 particles.
- the invention aims in particular at providing a continuous casting manufacturing method which does not present any particular difficulties when casting steels.
- the invention relates to a steel sheet whose chemical composition comprises, the contents being expressed by weight: 0.010% ⁇ C ⁇ 0.20%, 0.06% ⁇ Mn ⁇ 3%, Si ⁇ 1.5%, 0.005% ⁇ Al ⁇ 1.5%, S ⁇ 0.030%, P ⁇ 0.040%, of titanium and boron in quantities such that: 2.5% ⁇ Ti ⁇ 7.2%, (0, 45 xTi) - 0.35% ⁇ B ⁇ (0.45 xTi) + 0.70%, optionally one or more elements chosen from: Ni ⁇ 1%, Mo ⁇ 1%, Cr ⁇ 3%, Nb ⁇ 0, 1%, V ⁇ 0.1%, the remainder of the composition consisting of iron and unavoidable impurities resulting from the preparation.
- the titanium and boron contents are such that: -0.22 ⁇ B - (0.45 ⁇ Ti) ⁇ 0.35.
- the contents of titanium and boron, expressed as% by weight, are such that: -0.35 ⁇ B - (0.45 ⁇ Ti) - 0.22.
- the titanium content is preferably such that: 4.6% ⁇ Ti ⁇ 6.9%.
- the titanium content is such that: 4.6% ⁇ Ti ⁇ 6%.
- the carbon content is preferably such that: C ⁇ 0.080%.
- the carbon content satisfies: C ⁇ 0.050%.
- the chromium content is preferably such that: Cr ⁇ 0.08%.
- the invention also relates to a steel sheet of the above composition, comprising eutectic precipitates of TiB 2 and possibly Fe 2 B, whose average size is less than or equal to 15 micrometers, and preferably less than or equal to 10 micrometers.
- more than 80% by number of TiB 2 precipitates have a monocrystalline character.
- the invention also relates to a steel sheet according to the above characteristics, whose average grain size is less than or equal to 15 microns, preferably less than or equal to 5 microns, very preferably less than 3.5 microns.
- the invention also relates to a steel sheet according to one of the above characteristics, whose modulus of elasticity measured in the rolling direction is greater than or equal to 230GPa, preferably greater than or equal to 240GPa, or preferentially greater than or equal to 250GPa
- the strength of the steel sheet is greater than or equal to 500 MPa and its uniform elongation is greater than or equal to 8%.
- the subject of the invention is also an article manufactured from a plurality of steel parts, of identical or different composition, of identical or different thickness, at least one of the steel parts being a steel sheet. according to any of the above characteristics, welded to at least one of the other parts of this object, the composition or compositions of the other steel parts comprising by weight: 0.001-0.25% C, 0.05-2 % Mn, Si ⁇ 0.4%, Al ⁇ 0.1%, Ti ⁇ 0.1%, Nb ⁇ 0.1%, V ⁇ 0.1%, Cr ⁇ 3%, Mo ⁇ 1%, Ni ⁇ 1%, B ⁇ 0.003%, the remainder of the composition consisting of iron and unavoidable impurities resulting from the preparation.
- the invention also relates to a method according to which a steel is supplied according to any one of the above compositions, and the steel is cast in the form of a semi-finished product, the casting temperature not exceeding more than 40 ° C the liquidus temperature of the steel.
- the semi-finished product is cast as slabs or thin products between counter-rotating rolls.
- the cooling rate during the solidification of the casting is preferably greater than or equal to 0.1 ° C./s.
- the semi-finished product is heated before hot rolling, the temperature and the duration of the heating being chosen so that that the density of eutectic precipitates of TiB 2 and possibly Fe 2 B, of maximum size L max greater than 15 micrometers and of form factor f> 5, is less than 400 / mm 2 .
- the semi-finished product is thermally rolled, optionally cold rolling and annealing, the rolling and annealing conditions being adjusted so that a steel sheet whose size is obtained is obtained.
- grain average is less than or equal to 15 microns, preferably less than or equal to 5 microns, very preferably less than 3.5 microns.
- Hot rolling is preferably carried out with an end-of-rolling temperature of less than 820 ° C.
- At least one blank is cut from a steel sheet according to one of the above modes, or manufactured according to one of the above modes, and the blank is deformed in a temperature range from 20 ° to 900 ° C.
- the invention also relates to a manufacturing method according to which one welds at least one steel sheet according to one of the above modes, or a steel sheet manufactured according to one of the modes above.
- the invention also relates to the use of a steel sheet or an object according to one of the above modes, or manufactured according to one of the modes above, for the manufacture of parts of structure or reinforcement elements in the automotive field.
- the carbon content is limited because of the weldability: cold cracking resistance and heat-affected zone toughness decrease when the C content is greater than 0.20%.
- the carbon content is less than or equal to 0.050% by weight, the resistance weldability is particularly improved.
- the carbon content is preferably limited in order to avoid a primary precipitation of TiC and / or Ti (C, N) in the liquid metal. These precipitates which form in the liquid are detrimental to the flowability in the continuous casting process of the liquid steel. On the other hand, when this precipitation occurs in the solidification or solid phase interval, it has a favorable effect on the structural hardening.
- the maximum carbon content must therefore preferably be limited to 0.080% so as to reveal the TiC and / or Ti (C, N) precipitates, mainly during the eutectic or solid phase solidification.
- manganese increases the quenchability, contributes to hardening in solid solution and thus to obtaining increased strength. It combines with any sulfur present, reducing the risk of hot cracking. However, beyond a content of 3% by weight of manganese, the risk of formation of a harmful band structure that would come from a possible segregation of manganese during solidification.
- Silicon effectively contributes to increasing strength through solid solution hardening.
- an excessive addition of silicon causes the formation of adherent oxides that are difficult to remove during a stripping operation, and the possible appearance of surface defects due in particular to a lack of wettability in the dip galvanizing operations.
- the silicon content should not exceed 1.5% by weight.
- aluminum is a very effective element for the deoxidation of steel. Beyond a content of 1.5% by weight, excessive primary precipitation of alumina occurs, however, causing flowability problems.
- Phosphorus is a known element to segregate at grain boundaries. Its content must not exceed 0.040% so as to maintain a sufficient hot ductility by avoiding the creasability and to avoid hot cracking during welding.
- nickel or molybdenum can be added to increase the strength of the steel. For economic reasons, these additions are limited to 1% by weight.
- chromium can be added to increase the strength. It also makes it possible to precipitate borides in a larger quantity. However, its content is limited to 3% by weight to make a less expensive steel.
- a chromium content of less than or equal to 0.080% will be chosen.
- an excessive addition of Cr leads to more borides being precipitated, but these are borides of (Fe, Cr)
- niobium and vanadium may be added in an amount less than or equal to 0.1%, so as to obtain a complementary hardening in the form of precipitation of fine carbonitrides.
- a eutectic Fe-TiB 2 precipitation occurs during solidification.
- the eutectic character of the precipitation confers on the microstructure formed a particular character of fineness and homogeneity that is advantageous for the mechanical properties.
- the modulus of elasticity of the steel measured in the rolling direction may exceed about 220 GPa.
- the module can exceed 240 GPa approximately which allows to design structures with significant relief. This amount can be increased to 15% by volume to exceed about 250 GPa, especially in the case of steels comprising alloying elements such as chromium or molybdenum. The presence of these elements indeed increases the maximum amount of TiB 2 that can be obtained in the case of eutectic precipitation.
- the boron and titanium contents according to the invention make it possible to avoid a coarse primary precipitation of TiB 2 in the liquid metal.
- the formation of these primary precipitates of sometimes large size (several tens of micrometers) must be avoided because of their harmful role vis-à-vis mechanisms of damage or rupture during subsequent mechanical stresses.
- these precipitates appeared in the liquid metal, when they do not decant, are distributed in a localized manner and reduce the homogeneity of the mechanical properties. This early precipitation must be avoided because it can lead to a plugging of nozzles from the continuous casting of steel following the agglomeration of precipitates.
- titanium must be present in sufficient quantity to lead to the endogenous formation of TiB 2 in the form of eutectic Fe-TiB 2 precipitation.
- the titanium may also be present dissolved at room temperature in the matrix in an over-stoichiometric proportion relative to boron, calculated from TiB 2 .
- the precipitation takes place in the form of two successive eutectics: Fe-TiB 2 in the first place, then Fe-Fe 2 B, this second endogenous Fe 2 B precipitation intervenes in greater or lesser quantity depending on the boron content of the alloy.
- the amount precipitated as Fe 2 B can be up to 8% by volume.
- This second precipitation also occurs according to a eutectic scheme to obtain a fine and homogeneous distribution, which ensures a good homogeneity of the mechanical characteristics.
- Fe 2 B completes that of TiB 2 , the maximum amount of which is linked to the eutectic.
- Fe 2 B has a role similar to that of TiB 2 . It increases the modulus of elasticity and decreases the density. It is thus possible to adjust the mechanical properties in a fine way by adjusting the precipitation complement of Fe 2 B with respect to the precipitation of TiB 2 .
- This is a means that can be used in particular to obtain a modulus of elasticity greater than 250 GPa in steel as well as an increase in the mechanical strength of the product.
- the modulus of elasticity increases by more than 5 GPa.
- the elongation at break is then between 14% and 16% and the mechanical strength reaches 590 MPa.
- the amount of Fe 2 B is greater than 7.5% by volume, the modulus of elasticity is increased by more than 10 GPa but the elongation at break is then less than 9%.
- the average size of the eutectic precipitates of TiB 2 or Fe 2 B is less than or equal to 15 microns so as to obtain increased elongation characteristics and good fatigue properties.
- the elongation at break may be greater than 20%.
- the inventors have demonstrated that, when more than 80% of the number of TiB 2 eutectic precipitates have a monocrystalline character, the matrix-precipitated damage during a mechanical stress is reduced and the risk of defect formation is lower. because of the greater plasticity of the precipitate and its great cohesion with the matrix.
- larger TiB 2 precipitates have hexagonal crystallization. Without wishing to be bound by theory, it is believed that this crystallographic character confers an increased possibility of deformation by twinning of these precipitates under the effect of a mechanical stress.
- the inventors have shown that the limitation of the grain size was a very effective way to increase the mechanical characteristics of traction: When the average size grain is less than or equal to 15 micrometers, the resistance may exceed 560 MPa approximately. In addition, when the grain size is less than or equal to 3.5 micrometers, the resistance to cleavage is particularly high: Charpy resilience tests of thickness 3mm at -60 ° C, reveal that the proportion of ductile zone in broken test pieces is greater than 90%.
- the casting may be carried out in a format allowing the manufacture of products of various geometries, in particular in the form of a billet for the manufacture of long products.
- the fineness of the precipitation of TiB 2 and Fe 2 B increases the strength, ductility, resilience, formability and mechanical behavior in the Heat Affected Zone.
- the fineness of the precipitation is increased by a low casting temperature and a higher cooling rate. In particular, it has been found that a casting temperature limited to 40 ° C beyond the liquidus temperature, led to the obtaining of such fine microstructures.
- the casting conditions will also be chosen so that the cooling rate at the time of solidification is greater than or equal to 0.1 ° C./s so that the size of the precipitates of TiB 2 and Fe 2 B is particularly fine.
- the inventors have also demonstrated that the morphology of the eutectic precipitates of TiB 2 and Fe 2 B plays a role in the damage during a subsequent mechanical solidification. After observing the precipitates by optical microscopy at magnitudes ranging from 500 to 1500x approximately on a surface which has a statistically representative population, it is determined by means of an image analysis software known per se, such as, for example, the image analysis software Scion®., The maximum size L max and minimum L min of each precipitate. The ratio between maximum and minimum size The max The min characterizes the form factor f of a given precipitate. The inventors have shown that precipitates of large size (L max > 15 micrometers) and elongated (f> 5) reduce the distributed elongation and the coefficient of hardening n.
- the temperature and the reheating time of the semi-finished product are chosen before the subsequent hot rolling so as to cause a globulization of the most harmful precipitates.
- the temperature and the reheating time will be chosen so that the density of eutectic precipitates with a size L max > 15 microns and elongated (f> 5), ie less than 400 / mm 2 .
- an end of hot rolling temperature of less than 820 ° C. is an effective means for obtaining a fine grain size.
- the higher deformation field around the precipitates favors the germination of the grains during the restoration / recrystallization which follows the cold rolling, resulting in a refinement of the grain.
- the steel sheet thus obtained thus has a very good formability: without wishing to be bound by theory, it is believed that the eutectic precipitates present within a highly deformable matrix play a role similar to that played by the martensitic or bainitic phases within the ferrite in "Dual-Phase" type steels.
- the steels according to the invention have a ratio (elasticity limit Re / resistance Rm) favorable to various shaping operations.
- hot-rolled or hot-rolled sheets can be obtained.
- cold and annealed having matrices with various microstructures these may be totally or partially ferritic, bainitic, martensitic or austenitic.
- a steel containing 0.04% C, 5.9% Ti, 2.3% B will have, after cooling from 1200 ° C, a hardness ranging from 187 to 327 HV for a cooling rate of 5 at 150 ° C / sec.
- the highest levels of hardness correspond in this case to a totally bainitic matrix composed of slats with low disorientation, without carbides.
- a blank is cut from the sheet and deformation is carried out by means such as stamping, folding in a box.
- temperature range between 20 and 900 ° C. Very good thermal stability of the TiB 2 and Fe 2 B hardening phases is observed up to 1100 ° C.
- pieces of complex geometry with an increased modulus of elasticity can be produced according to the invention.
- the increase of the modulus of elasticity of the steels according to the invention decreases the springback after the shaping operations and thus increases the dimensional accuracy on finished parts.
- Structural elements are also advantageously manufactured by welding steels according to the invention, of identical or different composition or thickness so as to obtain in the final stage parts whose mechanical characteristics vary within them and are adapted locally. to subsequent solicitations.
- the composition by weight of steels that can be welded to the steels according to the invention will comprise, for example: 0.001-0.25% C, 0.05-2% Mn, Si ⁇ 0.4%, Al ⁇ 0.1%, Ti ⁇ 0.1%, Nb ⁇ 0.1%, V ⁇ 0.1%, Cr ⁇ 3%, Mo ⁇ 1%, Ni ⁇ 1%, B ⁇ 0.003%, the balance of the composition consisting of iron and unavoidable impurities resulting from the elaboration.
- composition I-1 and that of a reference steel R1 which does not contain endogenous eutectic precipitates of TiB 2 or Fe 2 B have been indicated for comparison purposes.
- microstructure in the raw state of casting illustrated in Figures 1 and 2 , relating respectively to the steels I-1 and I-2, shows a fine and homogeneous dispersion of endogenous precipitates of TiB 2 within a ferritic matrix. Boron precipitates as a Fe-TiB 2 binary eutectic.
- the volume amounts of precipitates were measured by means of an image analyzer and are respectively 9% and 12.4% for steels I-1 and I-2.
- the amount of TiB 2 in the form of primary precipitates is less than 2% by volume and promotes good flowability.
- the average sizes of the eutectic precipitates of TiB 2 are 5 and 8 microns respectively for the I-1 and I-2 steels. Among the population of these precipitates, more than 80% in number have a monocrystalline character.
- the semi-finished products were then hot-rolled in the form of sheets to a thickness of 3.5 mm, the end-of-rolling temperature being 940 ° C. Hot rolling was followed by winding at 700 ° C.
- Reheat treatments at 1230 ° C were also performed on the I-2 steel before hot rolling for varying periods of 30 to 120 minutes. The morphology of the precipitates was then observed. It has been demonstrated that a treatment at 1230 ° C. for a duration greater than or equal to 120 minutes makes it possible to globulate the precipitates so that the density of the eutectic precipitates of large size (L max > 15 micrometers) and elongated (f > 5) is less than 400 / mm 2 . The distributed elongation Au and the coefficient of hardening n are then significantly increased since they pass respectively from 11% and 0.125 (reheating time: 30 minutes) to 16% and 0.165 (reheating time 120 minutes) thanks to the treatment. of globulization of the precipitates. On the other hand, in the case of steel I-2, a sheet was hot rolled with a rolling end temperature of 810 ° C.
- the average grain size of steel I-1 is 12 micrometers whereas it is 28 micrometers for the reference steel.
- a low end-of-rolling temperature (810 ° C) leads to a very fine average grain size (3.5 micrometers) after hot rolling.
- the ratio Re / Rm of the hot-rolled or cold-rolled sheets according to the invention is close to 0.5, reflecting a mechanical behavior approaching that of a Dual-Phase steel and a good aptitude for subsequent shaping.
- Spot resistance welding tests were carried out on cold-rolled steel I-1 sheet: failure in tensile-shear tests occurs systematically by unsticking. It is known that this is a preferred mode of rupture because associated with high energy.
- eutectic precipitates according to the invention is also observed in welded melted zones, which contributes to a homogeneity of mechanical properties in welded joints. Satisfactory properties are also obtained in LASER welding and arc welding.
- Table 4 shows the composition of three steels according to the invention.
- Table 4 Steel compositions according to the invention (% by weight) Steel VS mn al Yes S P Ti B B- (0.45 xTi) I-3 0.0465 0.082 0.15 0.17 0.0014 0,008 5.5 2.8 0.32 I-4 0.0121 0.086 0.113 1.12 0,002 0,004 5.37 2.86 0.44 I-5 0.0154 0.084 0.1 0.885 0.0019 0,004 5.5 3.16 0.68
- the steels were produced by casting semi-finished products, the additions of titanium and boron being carried out in the form of ferroalloys.
- the casting temperature is 40 ° C above the liquidus temperature.
- the steels I-3 to I-5 have an excess of boron with respect to the stoichiometry of TiB 2 so that eutectic co-precipitation of TiB 2 and Fe 2 B occur.
- the volume amounts of eutectic precipitates are shown in Table 5.
- Table 5 Precipitation content (% by volume) relative to I-3-4-5 steels Steel % by volume TiB 2 % by volume Fe 2 B I-3 13 3.7 I-4 12.8 5.1 I-5 13 7.9
- the eutectic precipitates have an average size of less than 10 micrometers.
- the figure 4 illustrates, in the case of steel I-3, the coexistence of TiB 2 and Fe 2 B precipitates.
- the Fe 2 B precipitates appearing in light gray and the darker TiB 2 precipitates are scattered within the ferritic matrix.
- the semi-finished products were hot-rolled under the same conditions as those described in Example 1. Again, there is no damage to the precipitated-matrix interface.
- the figure 5 illustrates the microstructure of steel I-5. Characteristics of these hot-rolled steels are shown in Table 6. Table 6: Mechanical tensile characteristics of hot rolled sheets (direction parallel to rolling) and density. Steel E (GPa) Re (MPa) Rm (MPa) At (%) At (%) d I-3 245 279 511 10 14 7.32 I-4 250 284 590 11 14 7.32 I-5 254 333 585 8 9 7.30
- Semi-finished steel products of composition I-2 were cast at a temperature of 1330 ° C. By varying the intensity of the cooling flow of these semi-finished products, and the thickness of the cast half-products, two cooling rates were achieved, namely 0.8 and 12 ° C / s.
- the microstructures presented to Figures 6 and 7 illustrate that an increased cooling rate makes it possible to very significantly refine the eutectic Fe-TiB 2 precipitation.
- the TiB 2 precipitates are therefore present in the various zones of the bond (base metal, ZAC, molten zone), thus the increase of the modulus of elasticity and the reduction of the density are carried out in the whole of the welded joint.
- a steel sheet I-2 was also welded by LASER without any difficulty in operation with a soft steel plate embossissable whose composition contains (% by weight): 0.003% C, 0.098% Mn, 0.005% Si, 0.059% Al , 0.051% Ti, 0.0003% B, as well as unavoidable impurities resulting from the elaboration.
- the melted zone still contains Fe-TiB 2 eutectic precipitation, which is naturally less important than in the case of welding. autogenous. In this way, it is possible to manufacture metal structures whose stiffness properties vary locally and whose mechanical characteristics more specifically correspond to the local requirements for implementation or maintenance in service.
- the welding domain expressed in intensity I is between 7 and 8.5 kA.
- the two terminals of this domain correspond on the one hand to obtaining a core diameter greater than 5.2mm (lower limit in intensity) and on the other hand to the appearance of the spark when welding (terminal).
- the steel according to the invention therefore has good resistance to spot welding with a sufficiently wide weldability range of 1.5 kA.
- the invention thus allows the manufacture of structural parts or reinforcing elements with an increased level of performance, both in terms of intrinsic lightening as the increase of the modulus of elasticity.
- the easy welding of the steel sheets according to the invention makes their incorporation possible within more complex structures, in particular by means of connections with pieces of steels of different composition or thickness. We will take particular advantage of these different characteristics in the automotive field.
Landscapes
- 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)
- Heat Treatment Of Steel (AREA)
- Resistance Welding (AREA)
- Continuous Casting (AREA)
- Laminated Bodies (AREA)
Description
L'invention concerne la fabrication de tôles ou de pièces structurales en acier combinant simultanément un module d'élasticité E élevé, une densité d réduite et une haute résistance.The invention relates to the manufacture of steel sheets or structural parts simultaneously combining a high modulus of elasticity E, a reduced density and a high strength.
On sait que les performances mécaniques d'éléments structuraux varient comme Ex/d, le coefficient x dépendant du mode de sollicitation externe (traction ou flexion par exemple) ou de la géométrie des éléments (tôles, barres) Ceci illustre l'intérêt de disposer de matériaux présentant simultanément un module d'élasticité élevé et une densité réduite.It is known that the mechanical performances of structural elements vary like E x / d, the coefficient x depending on the mode of external stress (traction or bending for example) or the geometry of the elements (sheets, bars). This illustrates the interest of have materials simultaneously having a high modulus of elasticity and a reduced density.
Ce besoin existe tout particulièrement dans l'industrie automobile où l'allègement des véhicules et la sécurité sont des préoccupations constantes. On a cherché ainsi à augmenter le module d'élasticité et à réduire le poids de pièces en acier en incorporant des particules de céramiques de différentes natures, telles que carbures, nitrures, oxydes ou borures. En effet, ces matériaux présentent un module d'élasticité nettement plus élevé, allant environ de 250 à 550 GPa, que celui des aciers de base, de l'ordre de 210 GPa, où ils sont incorporés. On obtient de la sorte un durcissement par un transfert de charge entre la matrice et les particules de céramique sous l'influence d'une contrainte. L'affinement de la taille de grains de la matrice par les particules céramiques accroît en outre ce durcissement. Afin de fabriquer ces matériaux comportant des particules de céramique réparties de manière uniforme dans une matrice d'acier, on connaît des procédés qui sont basés sur la métallurgie des poudres : on élabore dans un premier temps des poudres de céramique à géométrie contrôlée, on mélange celles-ci à des poudres d'acier, ce qui correspond pour l'acier à un apport exogène de particules de céramique. Le tout est compacté en moule puis porté à une température telle que l'on observe le frittage de ce mélange. Dans une variante du procédé, on mélange des poudres métalliques de façon à obtenir la formation des particules de céramique lors de la phase de frittage. En dépit de caractéristiques mécaniques améliorées par rapport à des aciers ne comportant pas de dispersion de particules de céramique, ce type de procédé souffre de plusieurs limitations :
- Il nécessite des conditions soigneuses d'élaboration et de mise en oeuvre pour ne pas provoquer de réaction avec l'atmosphère, compte tenu de la surface spécifique élevée des poudres métalliques.
- Même après les opérations de compaction et de frittage, il peut subsister éventuellement des porosités résiduelles susceptibles de jouer un rôle de sites d'amorçage lors de sollicitations cycliques.
- La composition chimique des interfaces matrice/particules, et donc leur cohésion, est difficile à contrôler compte tenu de la contamination superficielle des poudres avant frittage (présence d'oxydes, de carbone)
- Lorsque les particules sont ajoutées en quantité importante, ou en présence de certaines particules de grande taille, les propriétés d'allongement diminuent.
- Ce type de procédé est adapté à la production en petite quantité mais ne saurait répondre aux besoins à très grande échelle de l'industrie automobile.
- Les coûts de fabrication associés à ce type de procédé de fabrication sont élevés.
- It requires careful conditions of development and implementation not to cause reaction with the atmosphere, given the high specific surface of the metal powders.
- Even after the compaction and sintering operations, residual porosities may remain possibly capable of acting as priming sites during cyclic stresses.
- The chemical composition of the matrix / particle interfaces, and therefore their cohesion, is difficult to control given the surface contamination of the powders before sintering (presence of oxides, carbon)
- When the particles are added in a large amount, or in the presence of certain large particles, the elongation properties decrease.
- This type of process is suitable for production in small quantities but can not meet the needs of the automotive industry on a very large scale.
- The manufacturing costs associated with this type of manufacturing process are high.
On connaît également dans le cas d'alliages légers, des procédés de fabrication reposant sur l'addition exogène de poudres de céramiques dans le métal liquide. Là encore, ces procédés soufrent de la plupart des défauts mentionnés ci-dessus. On mentionnera plus particulièrement la difficulté d'une dispersion homogène des particules, celles-ci ayant tendance à l'agglomération ou à la décantation/flottation dans le métal liquide.Also known in the case of light alloys, manufacturing processes based on the exogenous addition of powders of ceramics in the liquid metal. Again, these processes suffer from most of the defects mentioned above. More particularly, the difficulty of homogeneous dispersion of the particles, these having a tendency to agglomeration or decantation / flotation in the liquid metal.
Parmi les céramiques qui pourraient être utilisées pour accroître les propriétés des aciers, on connaît en particulier le diborure de titane TiB2 qui présente les caractéristiques intrinsèques suivantes :
- Module d'élasticité : 565 GPa
- Densité : 4,52
- Modulus of elasticity: 565 GPa
- Density: 4.52
Cependant, les procédés de fabrication reposant sur des additions exogènes de particules de TiB2, soufrent des inconvénients mentionnés précédemment.
L'invention vise à résoudre les problèmes ci-dessus, en particulier la mise à disposition à grande échelle et par une voie économique d'aciers à module d'élasticité accru par la présence de particules de TiB2. L'invention vise notamment à la mise à disposition d'un procédé de fabrication par coulée continue ne présentant pas de difficultés particulières lors de la coulée des aciers.The invention aims to solve the above problems, in particular the large scale and economical availability of steels with increased modulus of elasticity by the presence of TiB 2 particles. The invention aims in particular at providing a continuous casting manufacturing method which does not present any particular difficulties when casting steels.
Elle vise encore à mettre à disposition des aciers comportant une quantité de particules de TiB2 la plus importante possible dispersée de manière homogène dans la matrice.It also aims to provide steels with a quantity of TiB 2 particles as large as possible homogeneously dispersed in the matrix.
Elle vise encore à mettre à disposition des aciers à haute résistance, dont l'allongement uniforme soit supérieur ou égal à 8% et présentant une grande aptitude à différents procédés de soudage, notamment au soudage par résistance.It also aims to provide high strength steels, whose uniform elongation is greater than or equal to 8% and having a high ability to different welding processes, including resistance welding.
A cet effet, l'invention a pour objet une tôle d'acier dont la composition chimique comprend, les teneurs étant exprimées en poids: 0,010% ≤ C ≤ 0,20%, 0,06 % ≤ Mn ≤ 3%, Si ≤ 1,5%, 0,005% ≤ Al ≤ 1,5%, S ≤ 0,030%, P ≤ 0,040%, du titane et du bore en quantités telles que : 2,5% ≤ Ti ≤ 7,2%, (0,45 xTi) - 0,35% ≤ B ≤(0,45 xTi) + 0,70%, optionnellement un ou plusieurs éléments choisis parmi : Ni ≤ 1%, Mo ≤ 1%, Cr ≤ 3%, Nb ≤ 0,1%, V ≤ 0,1%, le reste de la composition étant constitué de fer et d'impuretés inévitables résultant de l'élaboration.For this purpose, the invention relates to a steel sheet whose chemical composition comprises, the contents being expressed by weight: 0.010% ≤ C ≤ 0.20%, 0.06% ≤ Mn ≤ 3%, Si ≤ 1.5%, 0.005% ≤ Al ≤ 1.5%, S ≤ 0.030%, P ≤ 0.040%, of titanium and boron in quantities such that: 2.5% ≤ Ti ≤ 7.2%, (0, 45 xTi) - 0.35% ≤ B ≤ (0.45 xTi) + 0.70%, optionally one or more elements chosen from: Ni ≤ 1%, Mo ≤ 1%, Cr ≤ 3%, Nb ≤ 0, 1%, V ≤ 0.1%, the remainder of the composition consisting of iron and unavoidable impurities resulting from the preparation.
Préférentiellement, les teneurs en titane et en bore, exprimées en % poids, sont telles que : -0,22 ≤ B - (0,45x Ti) ≤ 0,35.Preferably, the titanium and boron contents, expressed in% by weight, are such that: -0.22 ≤ B - (0.45 × Ti) ≤ 0.35.
A titre préféré, les teneurs en titane et en bore, exprimées en % poids, sont telles que : -0,35 ≤ B - (0,45x Ti) < - 0,22.As a preference, the contents of titanium and boron, expressed as% by weight, are such that: -0.35 ≤ B - (0.45 × Ti) - 0.22.
La teneur en titane est préférentiellement telle que : 4,6% ≤ Ti ≤ 6,9%.The titanium content is preferably such that: 4.6% ≤ Ti ≤ 6.9%.
Selon un mode particulier, la teneur en titane est telle que : 4,6% ≤ Ti ≤ 6%. La teneur en carbone est préférentiellement telle que : C ≤ 0,080%.According to one particular embodiment, the titanium content is such that: 4.6% ≤ Ti ≤ 6%. The carbon content is preferably such that: C ≤ 0.080%.
Selon un mode préféré, la teneur en carbone satisfait à : C ≤ 0,050%.According to a preferred embodiment, the carbon content satisfies: C ≤ 0.050%.
La teneur en chrome est préférentiellement telle que : Cr ≤ 0,08%. L'invention a également pour objet une tôle d'acier de composition ci-dessus, comprenant des précipités eutectiques de TiB2 et éventuellement de Fe2B, dont la taille moyenne est inférieure ou égale à 15 micromètres, et préférentiellement inférieure ou égale à 10 micromètres.The chromium content is preferably such that: Cr ≤ 0.08%. The invention also relates to a steel sheet of the above composition, comprising eutectic precipitates of TiB 2 and possibly Fe 2 B, whose average size is less than or equal to 15 micrometers, and preferably less than or equal to 10 micrometers.
Préférentiellement, plus de 80% en nombre des précipités de TiB2 ont un caractère monocristallin.Preferably, more than 80% by number of TiB 2 precipitates have a monocrystalline character.
L'invention a également pour objet une tôle d'acier selon les caractéristiques ci-dessus, dont la taille moyenne de grain est inférieure ou égale à 15 micromètres, préférentiellement inférieure ou égale à 5 micromètres, très préférentiellement inférieure à 3,5 micromètres.The invention also relates to a steel sheet according to the above characteristics, whose average grain size is less than or equal to 15 microns, preferably less than or equal to 5 microns, very preferably less than 3.5 microns.
L'invention a également pour objet une tôle d'acier selon l'une des caractéristiques ci-dessus, dont le module d'élasticité mesuré dans le sens du laminage est supérieur ou égal à 230GPa, préférentiellement supérieur ou égal à 240GPa, ou préférentiellement supérieur ou égal à 250GPaThe invention also relates to a steel sheet according to one of the above characteristics, whose modulus of elasticity measured in the rolling direction is greater than or equal to 230GPa, preferably greater than or equal to 240GPa, or preferentially greater than or equal to 250GPa
Selon un mode particulier, la résistance de la tôle d'acier est supérieure ou égale à 500MPa et son allongement uniforme est supérieur ou égal à 8%.In a particular embodiment, the strength of the steel sheet is greater than or equal to 500 MPa and its uniform elongation is greater than or equal to 8%.
L'invention a également pour objet un objet fabriqué à partir d'une pluralité de pièces d'acier, de composition identique ou différente, d'épaisseur identique ou différente, l'une au moins des pièces d'acier étant une tôle en acier selon l'une quelconque des caractéristiques ci-dessus, soudée à au moins une des autres pièces de cet objet, la ou les compositions des autres pièces d'acier comprenant en poids: 0,001-0,25%C, 0,05-2%Mn, Si≤0,4%, Al≤0,1%, Ti<0,1%, Nb<0,1%, V<0,1%, Cr<3%, Mo<1%, Ni<1%, B<0,003%, le reste de la composition étant constitué de fer et d'impuretés inévitables résultant de l'élaboration.The subject of the invention is also an article manufactured from a plurality of steel parts, of identical or different composition, of identical or different thickness, at least one of the steel parts being a steel sheet. according to any of the above characteristics, welded to at least one of the other parts of this object, the composition or compositions of the other steel parts comprising by weight: 0.001-0.25% C, 0.05-2 % Mn, Si≤0.4%, Al≤0.1%, Ti <0.1%, Nb <0.1%, V <0.1%, Cr <3%, Mo <1%, Ni < 1%, B <0.003%, the remainder of the composition consisting of iron and unavoidable impurities resulting from the preparation.
L'invention a également pour objet un procédé selon lequel on approvisionne un acier selon l'une quelconque des compositions ci-dessus, et l'on coule l'acier sous forme de demi-produit, la température de coulée n'excédant pas de plus de 40°C la température de liquidus de l'acier.The invention also relates to a method according to which a steel is supplied according to any one of the above compositions, and the steel is cast in the form of a semi-finished product, the casting temperature not exceeding more than 40 ° C the liquidus temperature of the steel.
Selon un mode particulier, on coule le demi-produit sous forme de brames ou de produits minces entre cylindres contra-rotatifs.According to a particular embodiment, the semi-finished product is cast as slabs or thin products between counter-rotating rolls.
La vitesse de refroidissement lors de la solidification de la coulée est préférentiellement supérieure ou égale à 0,1°C/s.The cooling rate during the solidification of the casting is preferably greater than or equal to 0.1 ° C./s.
Selon un mode particulier, on réchauffe le demi-produit avant laminage à chaud, la température et la durée du réchauffage étant choisies de telle sorte que la densité de précipités eutectiques de TiB2 et éventuellement de Fe2B, de taille maximale Lmax supérieure à 15 micromètres et de facteur de forme f>5, soit inférieure à 400/mm2.According to a particular mode, the semi-finished product is heated before hot rolling, the temperature and the duration of the heating being chosen so that that the density of eutectic precipitates of TiB 2 and possibly Fe 2 B, of maximum size L max greater than 15 micrometers and of form factor f> 5, is less than 400 / mm 2 .
Selon un mode particulier, on effectue un laminage à chaud du demi-produit, optionnellement un laminage à froid et un recuit, les conditions de laminage et de recuit étant ajustées de telle sorte que l'on obtienne une tôle d'acier dont la taille moyenne de grain est inférieure ou égale à 15 micromètres, préférentiellement inférieure ou égale à 5 micromètres, très préférentiellement inférieure à 3,5 micromètres.According to one particular embodiment, the semi-finished product is thermally rolled, optionally cold rolling and annealing, the rolling and annealing conditions being adjusted so that a steel sheet whose size is obtained is obtained. grain average is less than or equal to 15 microns, preferably less than or equal to 5 microns, very preferably less than 3.5 microns.
On effectue préférentiellement le laminage à chaud avec une température de fin de laminage inférieure à 820°C.Hot rolling is preferably carried out with an end-of-rolling temperature of less than 820 ° C.
Selon un mode particulier, on découpe au moins un flan à partir d'une tôle d'acier selon l'un des modes ci-dessus, ou fabriquée selon l'un des modes ci-dessus, et l'on déforme le flan dans une gamme de température allant de 20° à 900°C.According to a particular embodiment, at least one blank is cut from a steel sheet according to one of the above modes, or manufactured according to one of the above modes, and the blank is deformed in a temperature range from 20 ° to 900 ° C.
L'invention a également pour objet un procédé de fabrication selon lequel on soude au moins une tôle d'acier selon l'un des modes ci-dessus, ou une tôle d'acier fabriquée selon l'un des modes ci-dessus.The invention also relates to a manufacturing method according to which one welds at least one steel sheet according to one of the above modes, or a steel sheet manufactured according to one of the modes above.
L'invention a également pour objet l'utilisation d'une tôle d'acier ou d'un objet selon l'un des modes ci-dessus, ou fabriquée selon l'un des modes ci-dessus, pour la fabrication de pièces de structure ou d'éléments de renfort dans le domaine automobile.The invention also relates to the use of a steel sheet or an object according to one of the above modes, or manufactured according to one of the modes above, for the manufacture of parts of structure or reinforcement elements in the automotive field.
D'autres caractéristiques et avantages de l'invention apparaîtront au cours de la description ci-dessous, donnée à titre d'exemple non limitatif et en référence aux figures annexées dans lesquelles :
- Les
figures 1 et 2 illustrent respectivement la microstructure de deux aciers selon l'invention comportant une précipitation eutectique Fe-TiB2, à l'état brut de coulée.- La
figure 3 illustre la microstructure d'un acier selon l'invention à l'état laminé à froid et recuit.
- La
- Les
figures 4 et 5 illustrent la microstructure de deux aciers selon l'invention comportant des précipitations eutectiques Fe-TiB2 et de Fe-Fe2B, respectivement à l'état brut de coulée et laminé à chaud. - Les
figures 6 et 7 illustrent la microstructure d'un acier selon l'invention, refroidi selon deux vitesses de refroidissement lors de la solidification, à l'état brut de coulée - En ce qui concerne la composition chimique de l'acier, la teneur en carbone est adaptée dans le but d'atteindre de façon économique un niveau de limite d'élasticité ou de résistance donné. La teneur en carbone permet également de contrôler la nature de la microstructure de la matrice des aciers selon l'invention, qui peut être partiellement ou totalement ferritique, bainitique, austénitique ou martensitique ou comporter un mélange de ces constituants en proportion adaptées de manière à satisfaire aux propriétés mécaniques requises. Une teneur en carbone supérieure ou égale à 0,010% permet d'obtenir ces différents constituants.
- The
Figures 1 and 2 respectively illustrate the microstructure of two steels according to the invention comprising eutectic precipitation Fe-TiB 2 , in the raw state of casting.- The
figure 3 illustrates the microstructure of a steel according to the invention in the cold rolled and annealed state.
- The
- The
Figures 4 and 5 illustrate the microstructure of two steels according to the invention comprising eutectic precipitation Fe-TiB 2 and Fe-Fe 2 B, respectively in the raw state of casting and hot rolled. - The
Figures 6 and 7 illustrate the microstructure of a steel according to the invention, cooled according to two cooling speeds during solidification, in the raw state of casting - With regard to the chemical composition of the steel, the carbon content is adapted for the purpose of economically attaining a given level of yield strength or resistance. The carbon content also makes it possible to control the nature of the microstructure of the matrix of steels according to the invention, which can be partially or totally ferritic, bainitic, austenitic or martensitic or comprise a mixture of these constituents in proportion adapted to satisfy the mechanical properties required. A carbon content greater than or equal to 0.010% makes it possible to obtain these various constituents.
La teneur en carbone est limitée en raison de la soudabilité : la résistance à la fissuration à froid et la ténacité en Zone Affectée par la Chaleur décroissent lorsque la teneur en C est supérieure à 0,20%. Lorsque la teneur en carbone est inférieure ou égale à 0,050% en poids, la soudabilité par résistance est particulièrement améliorée.The carbon content is limited because of the weldability: cold cracking resistance and heat-affected zone toughness decrease when the C content is greater than 0.20%. When the carbon content is less than or equal to 0.050% by weight, the resistance weldability is particularly improved.
Compte tenu de la teneur en titane de l'acier, la teneur en carbone est limitée préférentiellement afin d'éviter une précipitation primaire de TiC et/ou de Ti(C,N) dans le métal liquide. Ces précipités qui se forment dans le liquide sont néfastes envers la coulabilité dans le procédé de coulée continue de l'acier liquide. Par contre, lorsque cette précipitation intervient dans l'intervalle de solidification ou en phase solide, elle a un effet favorable sur le durcissement structural. La teneur maximale en carbone doit donc être limitée préférentiellement à 0,080% de manière à faire apparaître les précipités de TiC et/ou de Ti(C, N) majoritairement au cours de la solidification eutectique ou en phase solide.Given the titanium content of the steel, the carbon content is preferably limited in order to avoid a primary precipitation of TiC and / or Ti (C, N) in the liquid metal. These precipitates which form in the liquid are detrimental to the flowability in the continuous casting process of the liquid steel. On the other hand, when this precipitation occurs in the solidification or solid phase interval, it has a favorable effect on the structural hardening. The maximum carbon content must therefore preferably be limited to 0.080% so as to reveal the TiC and / or Ti (C, N) precipitates, mainly during the eutectic or solid phase solidification.
En quantité supérieure ou égale à 0,06%, le manganèse augmente la trempabilité, contribue au durcissement en solution solide et donc à l'obtention d'une résistance accrue. Il se combine avec le soufre éventuellement présent, réduisant ainsi le risque de fissuration à chaud. Cependant au delà d'une teneur de 3% en poids de manganèse, on accroît le risque de formation d'une structure en bandes néfaste qui proviendrait d'une ségrégation éventuelle du manganèse lors de la solidification.In an amount greater than or equal to 0.06%, manganese increases the quenchability, contributes to hardening in solid solution and thus to obtaining increased strength. It combines with any sulfur present, reducing the risk of hot cracking. However, beyond a content of 3% by weight of manganese, the risk of formation of a harmful band structure that would come from a possible segregation of manganese during solidification.
Le silicium contribue efficacement à augmenter la résistance grâce à un durcissement par solution solide. Cependant une addition excessive de silicium provoque la formation d'oxydes adhérents difficilement éliminables lors d'une opération de décapage, et l'apparition éventuelle de défauts de surface dus notamment à un manque de mouillabilité dans les opérations de galvanisation au trempé. Afin de conserver de bonnes propriétés de revêtabilité, la teneur en silicium ne doit pas excéder 1,5% en poids.Silicon effectively contributes to increasing strength through solid solution hardening. However, an excessive addition of silicon causes the formation of adherent oxides that are difficult to remove during a stripping operation, and the possible appearance of surface defects due in particular to a lack of wettability in the dip galvanizing operations. In order to maintain good coating properties, the silicon content should not exceed 1.5% by weight.
En quantité supérieure ou égale à 0,005%, l'aluminium est un élément très efficace pour la désoxydation de l'acier. Au delà d'une teneur de 1,5% en poids, une précipitation primaire excessive d'alumine intervient cependant entraînant des problèmes de coulabilité.In an amount greater than or equal to 0.005%, aluminum is a very effective element for the deoxidation of steel. Beyond a content of 1.5% by weight, excessive primary precipitation of alumina occurs, however, causing flowability problems.
En quantité supérieure à 0,030%, le soufre tend à précipiter en quantité excessive sous forme de sulfures de manganèse qui réduisent très fortement l'aptitude à la mise en forme à chaud ou à froid.In excess of 0.030%, sulfur tends to precipitate excessively in the form of manganese sulfides which greatly reduce hot or cold forming ability.
Le phosphore est un élément connu pour ségréger aux joints de grains. Sa teneur ne doit pas excéder 0,040% de façon à maintenir une ductilité à chaud suffisante en évitant la criquabilité et à éviter la fissuration à chaud en soudage.Phosphorus is a known element to segregate at grain boundaries. Its content must not exceed 0.040% so as to maintain a sufficient hot ductility by avoiding the creasability and to avoid hot cracking during welding.
A titre optionnel, on peut ajouter du nickel ou du molybdène qui augmentent la résistance de l'acier. Pour des raisons économiques, on limite ces additions à 1% en poids.As an option, nickel or molybdenum can be added to increase the strength of the steel. For economic reasons, these additions are limited to 1% by weight.
A titre optionnel, le chrome peut être ajouté pour augmenter la résistance. Il permet également de faire précipiter des borures en quantité plus importante. Cependant, sa teneur est limitée à 3% en poids pour fabriquer un acier moins coûteux.As an option, chromium can be added to increase the strength. It also makes it possible to precipitate borides in a larger quantity. However, its content is limited to 3% by weight to make a less expensive steel.
On choisira préférentiellement une teneur en chrome inférieure ou égale à 0,080%. En effet, une addition excessive de Cr conduit à faire précipiter plus de borures, mais il s'agit alors de borures de (Fe, Cr)Preferably, a chromium content of less than or equal to 0.080% will be chosen. In fact, an excessive addition of Cr leads to more borides being precipitated, but these are borides of (Fe, Cr)
Egalement à titre optionnel, le niobium et le vanadium peuvent être ajoutés en quantité inférieure ou égale à 0,1%, de façon à obtenir un durcissement complémentaire sous forme de précipitation de carbonitrures fins.Also optionally, niobium and vanadium may be added in an amount less than or equal to 0.1%, so as to obtain a complementary hardening in the form of precipitation of fine carbonitrides.
Le titane et le bore jouent un rôle important dans l'invention :
- Dans un premier mode de réalisation, les teneurs pondérales exprimées en pourcents, en titane et en bore de l'acier sont telles que :
- In a first embodiment, the weight contents expressed in percent, titanium and boron of the steel are such that:
La seconde relation s'écrit de façon équivalente 
Les raisons de ces limitations sont les suivantes :
- Lorsque la teneur pondérale en titane est inférieure à 2,5%, une précipitation de TiB2 n'intervient pas en quantité suffisante ; en effet, la fraction volumique de TiB2 précipité est inférieure à 5%, ce qui ne permet pas d'obtenir une modification significative du module d'élasticité qui reste inférieur à 220GPa.
- Lorsque la teneur pondérale en titane est supérieure à 7,2%, une précipitation primaire grossière de TiB2 intervient dans le métal liquide et cause des problèmes de coulabilité des demi-produits.
- Si les teneurs pondérales en titane et en bore sont telles que :
- B- (0,45 xTi) > 0,70, on assiste à une précipitation excessive de Fe2B qui dégrade la ductilité.
- Si les teneurs pondérales en titane et en bore sont telles que :
- B- (0,45 xTi)< -0,35, la teneur en titane dissous à température ambiante dans la matrice est supérieure à 0,8%. Aucun effet technique bénéfique significatif n'est alors obtenu en dépit du coût plus élevé d'addition de titane.
- Selon un second mode de réalisation de l'invention, les teneurs en titane et en bore sont telles que : -0,22 ≤ B - (0,45x Ti) ≤ 0,35
- When the weight content of titanium is less than 2.5%, a precipitation of TiB 2 does not occur in sufficient quantity; indeed, the volume fraction of precipitated TiB 2 is less than 5%, which does not allow to obtain a significant modification of the modulus of elasticity which remains below 220GPa.
- When the weight content of titanium is greater than 7.2%, a coarse primary precipitation of TiB 2 occurs in the liquid metal and causes problems of flowability of the semi-finished products.
- If the weight contents of titanium and boron are such that:
- B- (0.45 xTi)> 0.70, there is an excessive precipitation of Fe 2 B which degrades the ductility.
- If the weight contents of titanium and boron are such that:
- B- (0.45 xTi) <-0.35, the content of titanium dissolved at room temperature in the matrix is greater than 0.8%. No significant beneficial technical effect is then obtained despite the higher cost of titanium addition.
- According to a second embodiment of the invention, the titanium and boron contents are such that: -0.22 ≤ B - (0.45 × Ti) ≤ 0.35
Lorsque : B- (0,45 xTi) ≤ 0,35, la précipitation de Fe2B est très réduite, ce qui augmente la ductilité.
- Lorsque : B- (0,45 xTi) ≥ -0,22, la teneur en titane dissous dans la matrice est très faible, ce qui signifie que les additions de titane sont particulièrement efficaces d'un point de vue économique.
- Selon un mode particulier de réalisation de l'invention, les teneurs en titane et en bore sont telles que : -0,35 ≤ B - (0,45x Ti) < - 0,22
- When: B- (0.45 xTi) ≥ -0.22, the titanium content dissolved in the matrix is very low, which means that the titanium additions are particularly economically efficient.
- According to a particular embodiment of the invention, the titanium and boron contents are such that: -0.35 ≤ B - (0.45 × Ti) - 0.22
Lorsque la quantité : B-(0,45xTi) est supérieure ou égale à -0,35 et inférieure à -0,22, la teneur en titane dissous à température ambiante dans la matrice est comprise respectivement entre 0,5% et 0,8%. Cette quantité se révèle particulièrement adaptée pour obtenir une précipitation composée uniquement de TiB2.
- Selon un mode particulier de réalisation de l'invention, la teneur en titane est telle que : 4,6% ≤ Ti ≤ 6,9%
- According to a particular embodiment of the invention, the titanium content is such that: 4.6% ≤ Ti ≤ 6.9%
Les raisons de ces limitations sont les suivantes :
- Lorsque la teneur pondérale en titane est supérieure ou égale à 4,6%, une précipitation de TiB2 intervient de telle sorte que la fraction volumique précipitée est supérieure ou égale à 10%. Le module d'élasticité est alors supérieur ou égal à environ 240 GPa.
- Lorsque la teneur pondérale en titane est inférieure ou égale à 6,9%, la quantité de précipités primaires de TiB2 est inférieure à 3% à volume. La précipitation totale de TiB2, constituée d'éventuels précipités primaires et de précipités eutectiques, est alors inférieure à 15% en volume.
- Selon un autre mode préféré de réalisation de l'invention, la teneur en titane est telle que : 4,6% ≤ Ti ≤ 6% : lorsque la teneur pondérale en titane est inférieure ou égale à 6%, la coulabilité est alors particulièrement satisfaisante en raison de la faible précipitation de TiB2 primaire dans le métal liquide.
- When the weight content of titanium is greater than or equal to 4.6%, a precipitation of TiB 2 occurs such that the volume fraction precipitated is greater than or equal to 10%. The modulus of elasticity is then greater than or equal to about 240 GPa.
- When the weight content of titanium is less than or equal to 6.9%, the amount of primary precipitates of TiB 2 is less than 3% by volume. The total precipitation of TiB 2 , consisting of possible primary precipitates and eutectic precipitates, is then less than 15% by volume.
- According to another preferred embodiment of the invention, the titanium content is such that: 4.6% ≤ Ti ≤ 6%: when the weight content of titanium is less than or equal to 6%, the flowability is then particularly satisfactory due to the low precipitation of primary TiB 2 in the liquid metal.
Selon l'invention, une précipitation eutectique Fe-TiB2 intervient à la solidification. Le caractère eutectique de la précipitation confère à la microstructure formée un caractère particulier de finesse et d'homogénéité avantageux pour les propriétés mécaniques. Lorsque la quantité de précipités eutectiques de TiB2 est supérieure à 5% en volume, le module d'élasticité de l'acier mesuré dans le sens du laminage peut dépasser 220 GPa environ. Au-delà de 10% en volume de précipités de TiB2, le module peut excéder 240 GPa environ ce qui permet de concevoir des structures avec un allègement notable. Cette quantité peut être portée à 15% en volume pour excéder 250 GPa environ, notamment dans le cas d'aciers comportant des éléments d'alliage tels que le chrome ou le molybdène. La présence de ces éléments augmente en effet la quantité maximale de TiB2 qu'il est possible d'obtenir dans le cas d'une précipitation eutectique.According to the invention, a eutectic Fe-TiB 2 precipitation occurs during solidification. The eutectic character of the precipitation confers on the microstructure formed a particular character of fineness and homogeneity that is advantageous for the mechanical properties. When the amount of TiB 2 eutectic precipitates is greater than 5% by volume, the modulus of elasticity of the steel measured in the rolling direction may exceed about 220 GPa. Beyond 10% by volume of TiB2 precipitates, the module can exceed 240 GPa approximately which allows to design structures with significant relief. This amount can be increased to 15% by volume to exceed about 250 GPa, especially in the case of steels comprising alloying elements such as chromium or molybdenum. The presence of these elements indeed increases the maximum amount of TiB 2 that can be obtained in the case of eutectic precipitation.
Les teneurs en bore et en titane selon l'invention permettent d'éviter une précipitation primaire grossière de TiB2 dans le métal liquide. La formation de ces précipités primaires de taille parfois importante (plusieurs dizaines de micromètres) doit être évitée en raison de leur rôle néfaste vis-à-vis de mécanismes d'endommagement ou de rupture lors de sollicitations mécaniques ultérieures. Par ailleurs ces précipités apparus dans le métal liquide, lorsqu'ils ne décantent pas, sont répartis de façon localisée et réduisent l'homogénéité des propriétés mécaniques. Cette précipitation précoce doit être évitée car elle peut conduire à un bouchage de busettes de la coulée continue de l'acier à la suite de l'agglomération de précipités. Comme on l'a exposé, le titane doit être présent en quantité suffisante pour conduire à la formation endogène de TiB2 sous la forme d'une précipitation eutectique Fe-TiB2. Selon l'invention, le titane peut être également présent dissous à température ambiante dans la matrice en proportion sur-stoechiométrique par rapport au bore, calculé à partir de TiB2.The boron and titanium contents according to the invention make it possible to avoid a coarse primary precipitation of TiB 2 in the liquid metal. The formation of these primary precipitates of sometimes large size (several tens of micrometers) must be avoided because of their harmful role vis-à-vis mechanisms of damage or rupture during subsequent mechanical stresses. Moreover, these precipitates appeared in the liquid metal, when they do not decant, are distributed in a localized manner and reduce the homogeneity of the mechanical properties. This early precipitation must be avoided because it can lead to a plugging of nozzles from the continuous casting of steel following the agglomeration of precipitates. As stated, titanium must be present in sufficient quantity to lead to the endogenous formation of TiB 2 in the form of eutectic Fe-TiB 2 precipitation. According to the invention, the titanium may also be present dissolved at room temperature in the matrix in an over-stoichiometric proportion relative to boron, calculated from TiB 2 .
Lorsque la teneur en titane en solution solide est inférieure à 0,5%, la précipitation intervient sous forme de deux eutectiques successifs : Fe-TiB2 en premier lieu, puis Fe-Fe2B, cette seconde précipitation endogène de Fe2B intervient en quantité plus ou moins importante selon la teneur en bore de l'alliage. La quantité précipitée sous forme de Fe2B peut aller jusqu'à 8% en volume. Cette seconde précipitation intervient aussi selon un schéma eutectique permettant d'obtenir une distribution fine et homogène, ce qui assure une bonne homogénéité des caractéristiques mécaniques.When the solid solution titanium content is less than 0.5%, the precipitation takes place in the form of two successive eutectics: Fe-TiB 2 in the first place, then Fe-Fe 2 B, this second endogenous Fe 2 B precipitation intervenes in greater or lesser quantity depending on the boron content of the alloy. The amount precipitated as Fe 2 B can be up to 8% by volume. This second precipitation also occurs according to a eutectic scheme to obtain a fine and homogeneous distribution, which ensures a good homogeneity of the mechanical characteristics.
La précipitation de Fe2B complète celle de TiB2 dont la quantité maximale est liée à l'eutectique. Le Fe2B a un rôle similaire à celui de TiB2. Il augmente le module d'élasticité et diminue la densité. Il est ainsi possible d'ajuster les propriétés mécaniques de façon fine en jouant sur le complément de précipitation du Fe2B par rapport à la précipitation de TiB2. C'est un moyen que l'on peut utiliser en particulier pour obtenir un module d'élasticité supérieur à 250 GPa dans l'acier ainsi qu'une augmentation de la résistance mécanique du produit. Lorsque l'acier contient une quantité de Fe2B en volume supérieure ou égale à 4%, le module d'élasticité augmente de plus de 5 GPa. L'allongement à rupture est alors compris entre 14% et 16% et la résistance mécanique atteint 590 MPa. Lorsque la quantité de Fe2B est supérieure à 7,5% en volume, le module d'élasticité est accru de plus de 10 GPa mais l'allongement à rupture est alors inférieur à 9%.The precipitation of Fe 2 B completes that of TiB 2 , the maximum amount of which is linked to the eutectic. Fe 2 B has a role similar to that of TiB 2 . It increases the modulus of elasticity and decreases the density. It is thus possible to adjust the mechanical properties in a fine way by adjusting the precipitation complement of Fe 2 B with respect to the precipitation of TiB 2 . This is a means that can be used in particular to obtain a modulus of elasticity greater than 250 GPa in steel as well as an increase in the mechanical strength of the product. When the steel contains a quantity of Fe 2 B in volume greater than or equal to 4%, the modulus of elasticity increases by more than 5 GPa. The elongation at break is then between 14% and 16% and the mechanical strength reaches 590 MPa. When the amount of Fe 2 B is greater than 7.5% by volume, the modulus of elasticity is increased by more than 10 GPa but the elongation at break is then less than 9%.
Selon l'invention, la taille moyenne des précipités eutectiques de TiB2 ou de Fe2B est inférieure ou égale à 15 micromètres de façon à obtenir des caractéristiques accrues d'allongement à rupture et de bonnes propriétés en fatigue.According to the invention, the average size of the eutectic precipitates of TiB 2 or Fe 2 B is less than or equal to 15 microns so as to obtain increased elongation characteristics and good fatigue properties.
Lorsque la taille moyenne de ces précipités eutectiques est inférieure ou égale à 10 micromètres, l'allongement à rupture peut être supérieur à 20%. Les inventeurs ont mis en évidence que, lorsque plus de 80% du nombre de précipités eutectiques de TiB2 ont un caractère monocristallin, l'endommagement matrice-précipité lors d'une sollicitation mécanique est réduit et le risque de formation de défauts est moindre en raison de la plus grande plasticité du précipité et de sa grande cohésion avec la matrice. En particulier, on a mis en évidence que les précipités TiB2 de plus grande taille ont une cristallisation hexagonale. Sans vouloir être lié par une théorie, on pense que ce caractère cristallographique confère une possibilité accrue de déformation par maclage de ces précipités sous l'effet d'une sollicitation mécanique.When the average size of these eutectic precipitates is less than or equal to 10 microns, the elongation at break may be greater than 20%. The inventors have demonstrated that, when more than 80% of the number of TiB 2 eutectic precipitates have a monocrystalline character, the matrix-precipitated damage during a mechanical stress is reduced and the risk of defect formation is lower. because of the greater plasticity of the precipitate and its great cohesion with the matrix. In particular, it has been demonstrated that larger TiB 2 precipitates have hexagonal crystallization. Without wishing to be bound by theory, it is believed that this crystallographic character confers an increased possibility of deformation by twinning of these precipitates under the effect of a mechanical stress.
Ce caractère particulier de monocristallinité, lié à la précipitation de TiB2 sous une forme eutectique, ne se rencontre pas à un tel degré pour les procédés de l'art antérieur reposant sur des apports exogènes de particules.This particular character of monocrystallinity, linked to the precipitation of TiB 2 in a eutectic form, does not meet to such a degree for the processes of the prior art based on exogenous inputs particles.
Outre l'effet favorable d'une dispersion de particules endogènes sur les propriétés mécaniques de traction, les inventeurs ont mis en évidence que la limitation de la taille de grain était un moyen très efficace pour accroître les caractéristiques mécaniques de traction : Lorsque la taille moyenne de grain est inférieure ou égale à 15 micromètres, la résistance peut excéder 560 MPa environ. De plus, lorsque la taille de grain est inférieure ou égale à 3,5 micromètres, la résistance au clivage est particulièrement élevée : des essais de résilience Charpy d'épaisseur 3mm à -60°C, révèlent que la proportion de zone ductile dans les éprouvettes rompues est supérieure à 90%.In addition to the favorable effect of a dispersion of endogenous particles on the mechanical properties of traction, the inventors have shown that the limitation of the grain size was a very effective way to increase the mechanical characteristics of traction: When the average size grain is less than or equal to 15 micrometers, the resistance may exceed 560 MPa approximately. In addition, when the grain size is less than or equal to 3.5 micrometers, the resistance to cleavage is particularly high: Charpy resilience tests of thickness 3mm at -60 ° C, reveal that the proportion of ductile zone in broken test pieces is greater than 90%.
La mise en oeuvre du procédé de fabrication d'une tôle selon l'invention est la suivante :
- On approvisionne un acier de composition selon l'invention
- On procède à la coulée d'un demi-produit à partir de cet acier. Cette coulée peut être réalisée en lingots ou en continu sous forme de brames d'épaisseur de l'ordre de 200mm. On peut également effectuer la coulée sous forme de brames minces de quelques dizaines de millimètres d'épaisseur ou de bandes minces, de quelques millimètres d'épaisseur, entre cylindres contra-rotatifs. Le dernier mode est particulièrement avantageux pour obtenir une fine précipitation eutectique et pour éviter la formation de précipités primaires. Une augmentation de la vitesse de refroidissement à la solidification accroît la finesse de la microstructure obtenue.
- A composition steel is supplied according to the invention
- A semi-finished product is cast from this steel. This casting can be carried out in ingots or continuously in the form of slabs of the order of 200mm thickness. It is also possible to perform the casting in the form of slabs of a few tens of millimeters thick or thin strips, a few millimeters thick, between contra-rotating cylinders. The latter mode is particularly advantageous for obtaining fine eutectic precipitation and for preventing the formation of primary precipitates. An increase in the cooling rate upon solidification increases the fineness of the resulting microstructure.
Bien naturellement, la coulée peut être réalisée dans un format permettant la fabrication de produits de diverses géométries, en particulier sous forme de billette pour la fabrication de produits longs.Naturally, the casting may be carried out in a format allowing the manufacture of products of various geometries, in particular in the form of a billet for the manufacture of long products.
La finesse de la précipitation de TiB2 et de Fe2B augmente la résistance, la ductilité, la résilience, l'aptitude au formage et le comportement mécanique en Zone Affectée par la Chaleur. On accroît la finesse de la précipitation grâce à une faible température de coulée et une vitesse de refroidissement plus importante. En particulier, on a découvert qu'une température de coulée limitée à 40°C au delà de la température de liquidus, conduisait à l'obtention de telles microstructures fines.The fineness of the precipitation of TiB 2 and Fe 2 B increases the strength, ductility, resilience, formability and mechanical behavior in the Heat Affected Zone. The fineness of the precipitation is increased by a low casting temperature and a higher cooling rate. In particular, it has been found that a casting temperature limited to 40 ° C beyond the liquidus temperature, led to the obtaining of such fine microstructures.
Les conditions de coulée seront également choisies de telle sorte que la vitesse de refroidissement au moment de la solidification soit supérieure ou égale à 0,1°C/s de façon à ce que la taille des précipités de TiB2 et de Fe2B soit particulièrement fine.The casting conditions will also be chosen so that the cooling rate at the time of solidification is greater than or equal to 0.1 ° C./s so that the size of the precipitates of TiB 2 and Fe 2 B is particularly fine.
Les inventeurs ont également mis en évidence que la morphologie des précipités eutectiques de TiB2 et de Fe2B joue un rôle sur l'endommagement lors d'une solidification mécanique ultérieure. Après observation des précipités par microscopie optique à des grandissements allant de 500 à 1500x environ sur une surface qui présente une population statistiquement représentative, on détermine au moyen d'un logiciel d'analyse d'images connu en lui-même tel que par exemple le logiciel d'analyse d'images Scion®., la taille maximale Lmax et minimale Lmin de chaque précipité. Le rapport entre la taille maximale et minimale 
Selon l'invention, après coulée du demi-produit, on choisit la température et le temps de réchauffage du demi-produit avant le laminage à chaud ultérieur de façon à provoquer une globulisation des précipités les plus néfastes. On choisira en particulier la température et le temps de réchauffage de telle sorte que la densité de précipités eutectiques avec une taille Lmax >15 microns et allongés (f>5), soit inférieure à 400/mm2.According to the invention, after casting of the semi-finished product, the temperature and the reheating time of the semi-finished product are chosen before the subsequent hot rolling so as to cause a globulization of the most harmful precipitates. In particular, the temperature and the reheating time will be chosen so that the density of eutectic precipitates with a size L max > 15 microns and elongated (f> 5), ie less than 400 / mm 2 .
On effectue ensuite un laminage à chaud du demi-produit, éventuellement suivi d'un bobinage. Optionnellement, on effectue un laminage à froid et un recuit pour obtenir des tôles d'épaisseur moins importante. On choisit les conditions de laminage à chaud, de bobinage, de laminage à froid, de recuit de telle sorte que l'on obtienne une tôle d'acier dont la taille moyenne de grain est inférieure ou égale à 15 micromètres, préférentiellement inférieure à 5 micromètres, très préférentiellement inférieure à 3,5 micromètres. Une taille de grain plus fine est obtenue par :
- un écrouissage important avant la fin du laminage à chaud et avant la transformation allotropique (γ-α) se produisant au refroidissement
- une température de fin de laminage basse, préférentiellement inférieure à 820°C
- un refroidissement accéléré après la transformation (γ-α) de façon à limiter la croissance du grain ferritique
- un bobinage à température relativement basse
- après un éventuel laminage à froid, une limitation de la température de recuit et du temps de recuit aux fins d'obtenir une recristallisation complète, sans dépassement de la température et du temps au delà des valeurs qui sont nécessaires à cette recristallisation.
- significant work hardening before the end of hot rolling and before the allotropic transformation (γ-α) occurring during cooling
- a low rolling end temperature, preferably less than 820 ° C.
- accelerated cooling after the transformation (γ-α) so as to limit the growth of the ferritic grain
- a relatively low temperature winding
- after a possible cold rolling, a limitation of the annealing temperature and the annealing time in order to obtain a complete recrystallization, without exceeding the temperature and time beyond the values which are necessary for this recrystallization.
Une température de fin de laminage à chaud inférieure à 820°C se révèle en particulier un moyen efficace pour obtenir une fine taille de grain. On a mis en évidence, dans les aciers selon l'invention, un effet particulier des précipités de TiB2 et Fe2B sur la germination et la recristallisation des microstructures : en effet, lors d'une déformation des aciers selon l'invention, la différence significative de comportement mécanique entre les précipités et la matrice conduit à une déformation plus importante autour des précipités. Cette déformation locale intense diminue la température de non-recristallisation : une température de fin de laminage faible favorise la germination ferritique autour des précipités et limite la croissance des grains.In particular, an end of hot rolling temperature of less than 820 ° C. is an effective means for obtaining a fine grain size. We put in obviously, in the steels according to the invention, a particular effect of the TiB 2 and Fe 2 B precipitates on the germination and the recrystallization of the microstructures: indeed, during a deformation of the steels according to the invention, the significant difference of Mechanical behavior between the precipitates and the matrix leads to greater deformation around the precipitates. This intense local deformation decreases the non-recrystallization temperature: a low rolling end temperature promotes ferritic germination around the precipitates and limits grain growth.
De même, le champ de déformation plus élevé autour des précipités favorise la germination des grains au cours de la restauration/recristallisation qui suit le laminage à froid, entraînant un affinement du grain.Likewise, the higher deformation field around the precipitates favors the germination of the grains during the restoration / recrystallization which follows the cold rolling, resulting in a refinement of the grain.
La tôle d'acier ainsi obtenue présente ainsi une très bonne aptitude à la mise en forme : sans vouloir être lié par une théorie, on pense que les précipités eutectiques présents au sein d'une matrice très déformable jouent un rôle similaire à celui que jouent les phases martensitiques ou bainitiques au sein de la ferrite dans les aciers de type « Dual-Phase ». Les aciers selon l'invention présentent un rapport (limite d'élasticité Re/résistance Rm) favorables à des opérations diverses de mise en forme.The steel sheet thus obtained thus has a very good formability: without wishing to be bound by theory, it is believed that the eutectic precipitates present within a highly deformable matrix play a role similar to that played by the martensitic or bainitic phases within the ferrite in "Dual-Phase" type steels. The steels according to the invention have a ratio (elasticity limit Re / resistance Rm) favorable to various shaping operations.
Selon la teneur en carbone et en éléments trempants, et selon la vitesse de refroidissement au dessous de la température Ar1 (cette température désignant le début de transformation au refroidissement à partir de l'austénite) on peut obtenir des tôles laminées à chaud ou laminées à froid et recuites comportant des matrices avec des microstructures diverses: celles-ci peuvent être totalement ou partiellement ferritiques, bainitiques, martensitiques ou austénitiques.Depending on the carbon content and the quenching elements, and depending on the cooling rate below the temperature Ar1 (this temperature designates the start of transformation on cooling from the austenite), hot-rolled or hot-rolled sheets can be obtained. cold and annealed having matrices with various microstructures: these may be totally or partially ferritic, bainitic, martensitic or austenitic.
Par exemple, un acier contenant 0,04%C, 5,9%Ti, 2,3%B présentera, après refroidissement à partir de 1200°C, une dureté allant de 187 à 327 HV pour une vitesse de refroidissement allant de 5 à 150°C/s. Les niveaux de dureté les plus élevés correspondent dans ce cas à une matrice totalement bainitique composée de lattes à faible désorientation, sans carbures.For example, a steel containing 0.04% C, 5.9% Ti, 2.3% B will have, after cooling from 1200 ° C, a hardness ranging from 187 to 327 HV for a cooling rate of 5 at 150 ° C / sec. The highest levels of hardness correspond in this case to a totally bainitic matrix composed of slats with low disorientation, without carbides.
Dans le cas où l'on souhaite réaliser une pièce comportant une opération de mise en forme, on découpe un flan à partir de la tôle et on effectue une déformation par des moyens tels que l'emboutissage, le pliage dans une gamme de température comprise entre 20 et 900°C. On observe une très bonne stabilité thermique des phases durcissantes TiB2 et Fe2B jusqu'à 1100°C.In the case where it is desired to produce a part comprising a shaping operation, a blank is cut from the sheet and deformation is carried out by means such as stamping, folding in a box. temperature range between 20 and 900 ° C. Very good thermal stability of the TiB 2 and Fe 2 B hardening phases is observed up to 1100 ° C.
Compte tenu de la stabilité thermique des particules dispersées dans la matrice et de la bonne aptitude aux différents procédés de formage à froid, à tiède ou à chaud, des pièces de géométrie complexe avec un module d'élasticité accru peuvent être réalisées selon l'invention. En outre, l'augmentation du module d'élasticité des aciers selon l'invention diminue le retour élastique après les opérations de mise en forme et permet d'accroître ainsi la précision dimensionnelle sur pièces finies.Given the thermal stability of the particles dispersed in the matrix and the good aptitude for the various cold, hot or hot forming processes, pieces of complex geometry with an increased modulus of elasticity can be produced according to the invention. . In addition, the increase of the modulus of elasticity of the steels according to the invention decreases the springback after the shaping operations and thus increases the dimensional accuracy on finished parts.
On fabrique aussi d'une manière avantageuse des éléments structuraux en soudant des aciers selon l'invention, de composition ou d'épaisseur identiques ou différentes de façon à obtenir au stade final des pièces dont les caractéristiques mécaniques varient en leur sein et sont adaptées localement aux sollicitations ultérieures.Structural elements are also advantageously manufactured by welding steels according to the invention, of identical or different composition or thickness so as to obtain in the final stage parts whose mechanical characteristics vary within them and are adapted locally. to subsequent solicitations.
Outre le fer et les inévitables impuretés, la composition en poids des d'aciers que l'on peut souder aux aciers selon l'invention comprendra par exemple : 0,001-0,25%C, 0,05-2%Mn, Si≤0,4%, Al≤0,1%, Ti<0,1%, Nb<0,1%, V<0,1%, Cr<3%, Mo<1%, Ni<1%, B<0,003%, le reste de la composition étant constitué de fer et d'impuretés inévitables résultant de l'élaboration.In addition to iron and the inevitable impurities, the composition by weight of steels that can be welded to the steels according to the invention will comprise, for example: 0.001-0.25% C, 0.05-2% Mn, Si≤ 0.4%, Al≤0.1%, Ti <0.1%, Nb <0.1%, V <0.1%, Cr <3%, Mo <1%, Ni <1%, B < 0.003%, the balance of the composition consisting of iron and unavoidable impurities resulting from the elaboration.
Dans la zone fondue, compte tenu de la température élevée atteinte, on assiste à une dissolution partielle des précipités ainsi qu'à leur reprécipitation au refroidissement. La quantité de précipités dans la zone fondue est très comparable à celle du métal de base. Au sein de la Zone Affectée par la Chaleur (ZAC) des joints soudés, les précipités eutectiques ne sont pas dissous et peuvent même servir de frein à la croissance du grain austénitique et de sites de germination éventuels lors de la phase de refroidissement ultérieure.In the melted zone, given the high temperature reached, there is a partial dissolution of the precipitates and their reprecipitation cooling. The amount of precipitates in the melted zone is very comparable to that of the base metal. Within the Heat Affected Zone (ZAC) of welded joints, eutectic precipitates are not dissolved and may even act as a brake on the growth of the austenitic grain and possible germination sites during the subsequent cooling phase.
Lors d'une mise en oeuvre par soudage des aciers selon l'invention, on obtient donc une homogénéité de la quantité de précipités de TiB2 et de Fe2B, qui va depuis le métal de base jusqu'au métal fondu en passant par la ZAC, ce qui garantit que les propriétés mécaniques visées (module, densité) seront elles aussi assurées de façon continue dans le cas de liaisons soudées.In a welding implementation of the steels according to the invention, a homogeneity of the amount of TiB 2 and Fe 2 B precipitates is thus obtained, which goes from the base metal to the molten metal via the ZAC, which ensures that the mechanical properties referred (module, density) will also be provided continuously in the case of welded connections.
A titre d'exemple non limitatif, les résultats suivants vont montrer les caractéristiques avantageuses conférées par l'invention.By way of non-limiting example, the following results will show the advantageous characteristics conferred by the invention.
On a élaboré des aciers dont la composition figure au tableau 1 ci-dessous, exprimée en pourcentage pondéral.Steels were made whose composition is shown in Table 1 below, expressed in weight percent.
Outre l'acier I-2 selon l'invention, on a indiqué à titre de comparaison la composition I-1 et celle d'un acier de référence R1 ne contenant pas de précipités eutectiques endogènes de TiB2 ou Fe2BIn addition to the steel I-2 according to the invention, the composition I-1 and that of a reference steel R1 which does not contain endogenous eutectic precipitates of TiB 2 or Fe 2 B have been indicated for comparison purposes.
Ces aciers ont été élaborés par coulée de demi-produits à partir de l'état liquide, les additions de titane et de bore étant effectuées pour les aciers I-1 et I-2 sous forme de ferro-alliages. La température de coulée est de 1330°C, soit un excès de 40°C par rapport à la température de liquidus.
La microstructure à l'état brut de coulée, illustrée aux
Les quantités volumiques de précipités ont été mesurées au moyen d'un analyseur d'images et sont respectivement de 9% et 12,4% pour les aciers I-1 et I-2. La quantité de TiB2 sous forme de précipités primaires est inférieure à 2% en volume et favorise une bonne coulabilité. Les tailles moyennes des précipités eutectiques de TiB2 sont respectivement de 5 et 8 micromètres pour les aciers I-1 et I-2. Parmi la population de ces précipités, plus de 80% en nombre ont un caractère monocristallin.The volume amounts of precipitates were measured by means of an image analyzer and are respectively 9% and 12.4% for steels I-1 and I-2. The amount of TiB 2 in the form of primary precipitates is less than 2% by volume and promotes good flowability. The average sizes of the eutectic precipitates of TiB 2 are 5 and 8 microns respectively for the I-1 and I-2 steels. Among the population of these precipitates, more than 80% in number have a monocrystalline character.
Après réchauffage à 1150°C, les demi-produits ont été ensuite laminés a chaud sous forme de tôles jusqu'à une épaisseur de 3,5 mm, la température de fin de laminage étant de 940°C. Le laminage à chaud a été suivi d'un bobinage à 700°C.After reheating to 1150 ° C., the semi-finished products were then hot-rolled in the form of sheets to a thickness of 3.5 mm, the end-of-rolling temperature being 940 ° C. Hot rolling was followed by winding at 700 ° C.
On a également effectué des traitements de réchauffage à 1230°C sur l'acier I-2 avant laminage à chaud, pendant des durées variables de 30 à 120 minutes. On a ensuite effectué des observations de la morphologie des précipités. On a mis en évidence qu'un traitement à 1230°C pendant une durée supérieure ou égale à 120 minutes permet de globuliser les précipités de telle sorte que la densité des précipités eutectiques de grande taille ( Lmax>15 micromètres) et allongés (f> 5) soit inférieure à 400/mm2. L'allongement réparti Au et le coefficient d'écrouissage n sont alors significativement augmentés puisqu'ils passent respectivement de 11% et de 0,125 (temps de réchauffage: 30 minutes) à 16% et 0,165 (temps de réchauffage 120 minutes) grâce au traitement de globulisation des précipités. Par ailleurs, dans le cas de l'acier I-2, une tôle a été laminée à chaud avec une température de fin de laminage de 810°C.Reheat treatments at 1230 ° C were also performed on the I-2 steel before hot rolling for varying periods of 30 to 120 minutes. The morphology of the precipitates was then observed. It has been demonstrated that a treatment at 1230 ° C. for a duration greater than or equal to 120 minutes makes it possible to globulate the precipitates so that the density of the eutectic precipitates of large size (L max > 15 micrometers) and elongated (f > 5) is less than 400 / mm 2 . The distributed elongation Au and the coefficient of hardening n are then significantly increased since they pass respectively from 11% and 0.125 (reheating time: 30 minutes) to 16% and 0.165 (reheating time 120 minutes) thanks to the treatment. of globulization of the precipitates. On the other hand, in the case of steel I-2, a sheet was hot rolled with a rolling end temperature of 810 ° C.
Ces tôles laminées à chaud ont été ensuite décapées selon un procédé connu en soi puis laminées à froid jusqu'à une épaisseur de 1 mm. On a ensuite effectué un recuit de recristallisation à 800°C - 1 minute de maintien, suivi d'un refroidissement à l'air.These hot-rolled sheets were then pickled according to a method known per se and then cold-rolled to a thickness of 1 mm. Recrystallization annealing was then carried out at 800 ° C. for 1 minute hold, followed by cooling in air.
Les observations effectuées par Microscopie Electronique à Balayage ne révèlent aucune décohésion à l'interface précipités eutectiques/matrice ou aucun endommagement des précipités eux-mêmes à la suite du laminage à chaud ou du laminage à froid.The observations made by Scanning Electron Microscopy reveal no decohesion at the eutectic precipitates / matrix interface or any damage to the precipitates themselves as a result of hot rolling or cold rolling.
Après laminage à chaud, la taille moyenne de grain de l'acier I-1 est de 12 micromètres alors qu'elle est de 28 micromètres pour l'acier de référence. Dans le cas de l'acier I-2, une faible température de fin de laminage (810°C) conduit à une taille moyenne de grain très fine (3,5 micromètres) après laminage à chaud.After hot rolling, the average grain size of steel I-1 is 12 micrometers whereas it is 28 micrometers for the reference steel. In the case of I-2 steel, a low end-of-rolling temperature (810 ° C) leads to a very fine average grain size (3.5 micrometers) after hot rolling.
Après laminage à froid et recuit, la structure des aciers I-1 et I-2 est recristallisée, comme l'indique la
Des mesures par pycnométrie indiquent que la présence des précipités de TiB2 et de Fe2B est associée à une réduction significative de la densité d puisque celle-ci passe de 7,80 (acier conventionnel R-1) à 7,33 (acier I-2) Les modules d'élasticité des aciers I-1 et I-2 mesurés dans le sens du laminage sont respectivement de 230 GPa et 240 GPa. Le module d'élasticité de l'acier de référence R-1 est de 210 GPa. Pour des tôles sollicitées en flexion dont l'indice de performance varie comme E1/3/d, l'utilisation des aciers selon l'invention permet une réduction de poids supérieure à 10% par rapport aux aciers conventionnels.Measurements by pycnometry indicate that the presence of precipitates of TiB 2 and Fe 2 B is associated with a significant reduction in the density d since this passes from 7.80 (conventional steel R-1) to 7.33 (steel I-2) The modulus of elasticity of I-1 and I-2 steels measured in the rolling direction are 230 GPa and 240 GPa, respectively. The modulus of elasticity of the reference steel R-1 is 210 GPa. For bending-stressed sheets whose performance index varies as E 1/3 / d, the use of the steels according to the invention allows a weight reduction of greater than 10% compared with conventional steels.
Les propriétés mécaniques de traction mesurées (limite d'élasticité conventionnelle Re mesurée à 0,2% de déformation, résistance Rm, allongement uniforme Au, allongement à rupture At) ont été portées au tableau 2 (tôles laminées à chaud) ou 3 (tôles laminées à froid et recuites) ci-dessous.
Le rapport Re/Rm des tôles laminées à chaud ou à froid selon l'invention est voisin de 0,5, traduisant un comportement mécanique se rapprochant de celui d'un acier Dual-Phase et une bonne aptitude à une mise en forme ultérieure. Des essais de soudage par résistance par points ont été effectués sur des tôles laminées à froid de l'acier I-1 : la rupture lors d'essais de traction-cisaillement se produit systématiquement par déboutonnage. On sait qu'il s'agit là d'un mode de rupture préféré car associé à une énergie élevée.The ratio Re / Rm of the hot-rolled or cold-rolled sheets according to the invention is close to 0.5, reflecting a mechanical behavior approaching that of a Dual-Phase steel and a good aptitude for subsequent shaping. Spot resistance welding tests were carried out on cold-rolled steel I-1 sheet: failure in tensile-shear tests occurs systematically by unsticking. It is known that this is a preferred mode of rupture because associated with high energy.
On relève également au sein des zones fondues en soudage la présence de précipités eutectiques selon l'invention, ce qui contribue à une homogénéité des propriétés mécaniques dans les assemblages soudés Des propriétés satisfaisantes sont également obtenues en soudage LASER et à l'arc.The presence of eutectic precipitates according to the invention is also observed in welded melted zones, which contributes to a homogeneity of mechanical properties in welded joints. Satisfactory properties are also obtained in LASER welding and arc welding.
Le tableau 4 ci-dessous présente la composition de trois aciers selon l'invention.
Les aciers ont été élaborés par coulée de demi-produits, les additions de titane et de bore étant effectuées sous forme de ferro-alliages. La température de coulée est de 40°C au dessus de la température de liquidus. En comparaison des aciers I-1 et I-2, les aciers I-3 à I-5 présentent un excès de bore par rapport à la stoechiométrie de TiB2 de telle sorte que des co-précipitations eutectiques de TiB2 puis de Fe2B se produisent. Les quantités volumiques de précipités eutectiques ont été portées au tableau 5.
Les précipités eutectiques ont une taille moyenne inférieure à 10 micromètres. La
Les demi-produits ont été laminés à chaud dans des conditions identiques à celles exposées dans l'exemple 1. On n'observe pas, là encore, d'endommagement à l'interface précipités-matrice. La
Par rapport aux aciers I-1 et I-2, une précipitation eutectique complémentaire de Fe2B en quantité volumique allant de 3 à 7,9% augmente le module d'élasticité de 5 à 15 GPa.With respect to the steels I-1 and I-2, a complementary eutectic precipitation of Fe 2 B in a volume amount ranging from 3 to 7.9% increases the modulus of elasticity from 5 to 15 GPa.
La précipitation complémentaire de Fe2B augmente la résistance mécanique, Lorsque cette précipitation intervient dans des proportions excessives, l'allongement uniforme peut cependant être nettement inférieur à 8%.The additional precipitation of Fe 2 B increases the mechanical strength. When this precipitation occurs in excessive proportions, the uniform elongation can however be significantly lower than 8%.
Des demi-produits d'acier de composition I-2 ont été coulés à une température de 1330°C. En faisant varier l'intensité du débit de refroidissement de ces demi-produits, et l'épaisseur des demi-produits coulés, deux vitesses de refroidissement ont été réalisées, soit 0,8 et 12°C/s. Les microstructures présentées aux
Des tôles d'acier de composition I-2 de 2,5mm d'épaisseur ont été soudées par LASER CO2 dans les conditions suivantes : Puissance : 5,5kW, vitesse de soudage : 3m/mn. Des observations micrographiques dans la zone fondue montrent qu'une précipitation eutectique Fe-TiB2 intervient sous une forme très fine lors du refroidissement à partir de l'état liquide. La quantité de précipités dans la zone fondue est voisine de celle du métal de base. Selon les conditions locales de refroidissement au moment de la solidification (gradient local G de température, vitesse de déplacement R des isothermes), la solidification intervient sous forme dendritique ou sous forme cellulaire. La morphologie dendritique se rencontre plus volontiers à la liaison avec la Zone Affectée par la Chaleur, compte tenu des conditions locales de solidification (gradient G important, vitesse R faible).Steel sheets of composition I-2 2.5 mm thick were welded by LASER CO 2 under the following conditions: Power: 5.5kW, welding speed: 3m / min. Micrographic observations in the melted zone show that a eutectic Fe-TiB 2 precipitation occurs in a very fine form during cooling from the liquid state. The amount of precipitates in the melted zone is close to that of the base metal. Depending on the local cooling conditions at the time of solidification (local gradient G of temperature, speed of displacement R of the isotherms), the solidification takes place in dendritic form or in cellular form. The dendritic morphology is more likely to be associated with the Heat Affected Zone, given the local solidification conditions (high G gradient, low R speed).
Les précipités de TiB2 sont donc présents dans les différentes zones de la liaison (métal de base, ZAC, zone fondue), ainsi l'augmentation du module d'élasticité et la réduction de la densité sont réalisées dans l'ensemble de l'assemblage soudé.The TiB 2 precipitates are therefore present in the various zones of the bond (base metal, ZAC, molten zone), thus the increase of the modulus of elasticity and the reduction of the density are carried out in the whole of the welded joint.
Une tôle d'acier I-2 a également été soudée par LASER sans difficulté opératoire avec une tôle d'acier doux emboutissable dont la composition contient (% en poids) : 0,003%C, 0,098%Mn, 0,005%Si, 0,059%Al, 0,051%Ti, 0,0003%B, ainsi que des impuretés inévitables résultant de l'élaboration. La zone fondue comporte encore une précipitation eutectique Fe-TiB2, en proportion naturellement moins importante que dans le cas d'un soudage autogène. De la sorte, il est possible de fabriquer des structures métalliques dont les propriétés de rigidité varient localement et dont les caractéristiques mécaniques correspondent plus spécifiquement aux exigences locales de mise en oeuvre ou de tenue en service.A steel sheet I-2 was also welded by LASER without any difficulty in operation with a soft steel plate embossissable whose composition contains (% by weight): 0.003% C, 0.098% Mn, 0.005% Si, 0.059% Al , 0.051% Ti, 0.0003% B, as well as unavoidable impurities resulting from the elaboration. The melted zone still contains Fe-TiB 2 eutectic precipitation, which is naturally less important than in the case of welding. autogenous. In this way, it is possible to manufacture metal structures whose stiffness properties vary locally and whose mechanical characteristics more specifically correspond to the local requirements for implementation or maintenance in service.
Des tôles laminées à froid et recuites d'acier I-2 selon l'invention, d'épaisseur 1,5mm ont été assemblées en soudage par résistance par point dans les conditions suivantes :
- Effort d'assemblage : 650daN
- Cycle de soudage : 3 x (7 périodes de passage du courant à une intensité 1 + 2 périodes sans passage de courant)
- Assembly effort: 650daN
- Welding cycle: 3 x (7 periods of current flow at an intensity 1 + 2 periods without current flow)
Le domaine de soudage exprimé en intensité I est compris entre 7 et 8,5kA. Les deux bornes de ce domaine correspondent d'une part à l'obtention d'un diamètre de noyau supérieur à 5,2mm (borne inférieure en intensité) et d'autre part à l'apparition de l'étincelage lors du soudage (borne supérieure) L'acier selon l'invention présente donc une bonne aptitude au soudage par résistance par points avec un domaine de soudabilité suffisamment large, de 1,5kA.The welding domain expressed in intensity I is between 7 and 8.5 kA. The two terminals of this domain correspond on the one hand to obtaining a core diameter greater than 5.2mm (lower limit in intensity) and on the other hand to the appearance of the spark when welding (terminal The steel according to the invention therefore has good resistance to spot welding with a sufficiently wide weldability range of 1.5 kA.
L'invention permet ainsi la fabrication de pièces de structure ou d'éléments de renfort avec un niveau de performance accru, tant sur le plan de l'allègement intrinsèque que de l'augmentation du module d'élasticité. La mise en oeuvre aisée par soudage des tôles d'aciers selon l'invention rend leur incorporation possible au sein de structures plus complexes en particulier au moyen de liaisons avec des pièces d'aciers de composition ou d'épaisseur différentes. On tirera tout particulièrement profit de ces différentes caractéristiques dans le domaine automobile.The invention thus allows the manufacture of structural parts or reinforcing elements with an increased level of performance, both in terms of intrinsic lightening as the increase of the modulus of elasticity. The easy welding of the steel sheets according to the invention makes their incorporation possible within more complex structures, in particular by means of connections with pieces of steels of different composition or thickness. We will take particular advantage of these different characteristics in the automotive field.
Claims (24)
- Steel sheet having the chemical composition expressed in weight contents of:
- Steel sheet according to claim 1, characterized in that the contents of titanium and boron are such that:
- Steel sheet according to claim 1, characterized in that the contents of titanium and boron are such that:
- Steel sheet according to any of claims 1 to 3, characterized in that its composition comprises, the content being expressed by weight:
- Steel sheet according to any of claims 1 to 4, characterized in that its composition comprises, the content being expressed by weight:
- Steel sheet according to any of claims 1 to 5, characterized in that its composition comprises, the content being expressed by weight:
- Steel sheet according to any of claims 1 to 6, characterized in that it comprises eutectic precipitates of TiB2 and optionally Fe2B having a mean size of 15 micrometres or less.
- Steel sheet according any of claims 1 to 7, characterized in that it comprises eutectic precipitates of TiB2 and optionally Fe2B having a mean size of 10 micrometres or less,
- Steel sheet according to claim 8, characterized in that more than 80 % by number of said TiB2 precipitates are of monocrystalline type,
- Steel sheet according to any of claims 1 to 9, characterized in that the mean grain size of said steel is 15 micrometres or less.
- Steel sheet according to any of claims 1 to 10, characterized in that the mean grain size of said steel is 5 micrometres or less.
- Steel sheet according to any of claims 1 to 11, characterized in that the mean grain size of said steel is 3.5 micrometres or less.
- Steel sheet according to any of claims 1 to 12, characterized in that its modulus of elasticity measured in the direction of rolling is 230 GPa or higher.
- Steel sheet according to any of claims 1 to 13, characterized in that its modulus of elasticity measured in the direction of rolling is 240 GPa or higher.
- Steel sheet according to any of claims 1 to 14, characterized in that its modulus of elasticity measured in the direction of rolling is 250 GPa or higher.
- Steel sheet according to any of claims 1 to 14, characterized in that its strength is 500 MPa or higher, and its uniform elongation is 8 % or higher.
- Manufacturing process whereby steel according to any of the compositions 1 to 6 is provided, said steel is cast into a semi-finished product, the casting temperature not exceeding the liquidus temperature of said steel by more than 40°C.
- Manufacturing process according to claim 17, characterized in that said semi-finished product is cast into a thin slab or thin strip between counter-rotating rollers.
- Manufacturing process according to claim 17 or 18, characterized in that the cooling rate of said cast on solidification is 0.1°C/s or higher.
- Process according to any of claims 17 to 19, characterized in that hot rolling of said semi-finished product is performed, optionally cold rolling and annealing, the rolling and annealing conditions being adjusted so that a steel sheet is obtained having a mean grain size of 15 micrometres or less.
- Process according to any of claims 17 to 20, characterized in that hot rolling of said semi-finished product is performed, optionally cold rolling and annealing, the rolling and annealing conditions being adjusted so that a steel sheet is obtained having a mean grain size of 5 micrometres or less.
- Process according to any of claims 17 to 21, characterized in that hot rolling of said semi-finished product is performed, optionally cold rolling and annealing, the rolling and annealing conditions being adjusted so that a steel sheet is obtained having a mean grain size of 3.5 micrometres or less.
- Process according to any of claims 20 to 22, characterized in that said hot rolling is performed with a finish rolling temperature lower than 820°C.
- Use of steel sheet according to any of claims 1 to 16, or manufactured by a process according to any of claims 17 to 23, to produce structural parts or reinforcement elements in the automobile sector.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP07823448.1A EP2064360B1 (en) | 2006-09-06 | 2007-08-27 | Steel sheet for the manufacture of light structures and manufacturing process of this sheet |
| PL07823448T PL2064360T3 (en) | 2006-09-06 | 2007-08-27 | Steel sheet for the manufacture of light structures and manufacturing process of this sheet |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP06291413A EP1897963A1 (en) | 2006-09-06 | 2006-09-06 | Steel sheet for the manufacture of light structures and manufacturing process of this sheet |
| EP07823448.1A EP2064360B1 (en) | 2006-09-06 | 2007-08-27 | Steel sheet for the manufacture of light structures and manufacturing process of this sheet |
| PCT/FR2007/001401 WO2008029011A2 (en) | 2006-09-06 | 2007-08-27 | Steel plate for producing light structures and method for producing said plate |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP2064360A2 EP2064360A2 (en) | 2009-06-03 |
| EP2064360B1 true EP2064360B1 (en) | 2017-12-27 |
Family
ID=37496804
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP06291413A Withdrawn EP1897963A1 (en) | 2006-09-06 | 2006-09-06 | Steel sheet for the manufacture of light structures and manufacturing process of this sheet |
| EP07823448.1A Active EP2064360B1 (en) | 2006-09-06 | 2007-08-27 | Steel sheet for the manufacture of light structures and manufacturing process of this sheet |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP06291413A Withdrawn EP1897963A1 (en) | 2006-09-06 | 2006-09-06 | Steel sheet for the manufacture of light structures and manufacturing process of this sheet |
Country Status (16)
| Country | Link |
|---|---|
| EP (2) | EP1897963A1 (en) |
| JP (1) | JP5298017B2 (en) |
| KR (1) | KR20090043555A (en) |
| CN (1) | CN101563476B (en) |
| BR (1) | BRPI0716877B1 (en) |
| CA (1) | CA2662741C (en) |
| ES (1) | ES2659987T3 (en) |
| HU (1) | HUE036845T2 (en) |
| MA (1) | MA30698B1 (en) |
| MX (1) | MX2009002411A (en) |
| PL (1) | PL2064360T3 (en) |
| RU (1) | RU2416671C2 (en) |
| TR (1) | TR201802707T4 (en) |
| UA (1) | UA95490C2 (en) |
| WO (1) | WO2008029011A2 (en) |
| ZA (1) | ZA200901377B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR3114447A1 (en) * | 2020-09-24 | 2022-03-25 | Constellium Neuf-Brisach | STEEL BATTERY BOTTOM FOR ELECTRIC VEHICLES |
Families Citing this family (21)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5375241B2 (en) * | 2009-03-24 | 2013-12-25 | Ｊｆｅスチール株式会社 | High strength thin steel sheet and method for producing the same |
| WO2013050397A1 (en) | 2011-10-04 | 2013-04-11 | Tata Steel Nederland Technology Bv | Steel product with improved e-modulus and method for producing said product |
| JP6048072B2 (en) * | 2011-11-24 | 2016-12-21 | Ｊｆｅスチール株式会社 | Hot rolled steel sheet for die quench, method for producing the same, and molded product using the same |
| WO2013171231A1 (en) | 2012-05-14 | 2013-11-21 | Tata Steel Nederland Technology Bv | High strength steel with increased e-modulus and method for producing said steel |
| EP2703510A1 (en) | 2012-08-28 | 2014-03-05 | Tata Steel Nederland Technology B.V. | Particle-reinforced steel with improved E-modulus and method for producing said steel |
| EP2703509A1 (en) | 2012-08-28 | 2014-03-05 | Tata Steel Nederland Technology B.V. | TiC- and TiB2-Particles reinforced high strength and low density steel with improved E-modulus and method for producing said steel |
| KR20150082199A (en) | 2012-09-14 | 2015-07-15 | 타타 스틸 네덜란드 테크날러지 베.뷔. | High strength and low density particle-reinforced steel with improved ｅ-modulus and method for producing said steel |
| EP2895637B1 (en) | 2012-09-14 | 2016-11-23 | Tata Steel Nederland Technology B.V. | Tic-particle-reinforced high strength and low density steel products with improved e-modulus and method for producing said product |
| WO2015001367A1 (en) | 2013-07-04 | 2015-01-08 | Arcelormittal Investigación Y Desarrollo Sl | Cold rolled steel sheet, method of manufacturing and vehicle |
| WO2015185956A1 (en) * | 2014-06-06 | 2015-12-10 | ArcelorMittal Investigación y Desarrollo, S.L. | High strength multiphase galvanized steel sheet, production method and use |
| CN105838993B (en) * | 2016-04-05 | 2018-03-30 | 宝山钢铁股份有限公司 | Lightweight steel, steel plate and its manufacture method with enhancing modulus of elasticity feature |
| US11725265B2 (en) | 2017-04-21 | 2023-08-15 | Arcelormittal | High formability steel sheet for the manufacture of lightweight structural parts and manufacturing process |
| CN110582588B (en) | 2017-04-21 | 2021-09-21 | 安赛乐米塔尔公司 | High-formability steel sheet for manufacturing lightweight structural members and manufacturing method |
| KR102561512B1 (en) * | 2019-03-20 | 2023-08-01 | 닛폰세이테츠 가부시키가이샤 | Non-oriented electrical steel sheet and manufacturing method thereof |
| CN114786844B (en) * | 2019-12-20 | 2023-12-19 | 安赛乐米塔尔公司 | Metal powder for additive manufacturing |
| WO2021123896A1 (en) * | 2019-12-20 | 2021-06-24 | Arcelormittal | Metal powder for additive manufacturing |
| CN110976796B (en) * | 2019-12-24 | 2021-03-16 | 江苏集萃安泰创明先进能源材料研究院有限公司 | Preparation method of amorphous alloy thin strip capable of reducing residual thermal stress |
| KR102273869B1 (en) * | 2020-06-02 | 2021-07-06 | 현대제철 주식회사 | Aluminum coated blank, manufacturing method thereof and manufacturing device for aluminum coated blank |
| CN113897540A (en) * | 2020-06-22 | 2022-01-07 | 上海梅山钢铁股份有限公司 | High-strength cold-rolled steel plate for precisely-stamped automobile seat adjuster fluted disc |
| CN113174545B (en) * | 2021-04-28 | 2022-12-09 | 上海交通大学 | In-situ nanoparticle reinforced FeCrB alloy with high-temperature oxidation resistance and preparation method thereof |
| WO2024018255A1 (en) * | 2022-07-19 | 2024-01-25 | Arcelormittal | Method of welding a steel sheet comprising tib2 precipitates |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS59153837A (en) * | 1983-02-22 | 1984-09-01 | Sumitomo Metal Ind Ltd | Production of high strength cold-rolled steel sheet for press-forming use |
| SU1122009A1 (en) * | 1983-07-19 | 1996-12-10 | Научно-Производственное Объединение По Технологии Машиностроения "Цниитмаш" | Corrosion-resistant steel |
| KR100252237B1 (en) * | 1996-04-25 | 2000-04-15 | 정몽규 | Mg alloy for high pressure casting |
| JP3478930B2 (en) * | 1996-08-29 | 2003-12-15 | 株式会社神戸製鋼所 | High rigidity and high toughness steel and method of manufacturing the same |
| JPH10237583A (en) * | 1997-02-27 | 1998-09-08 | Sumitomo Metal Ind Ltd | High tensile strength steel and its production |
| FR2819825B1 (en) * | 2001-01-24 | 2003-10-31 | Imphy Ugine Precision | PROCESS FOR MANUFACTURING A FE-NI ALLOY STRIP |
| JP3592659B2 (en) * | 2001-08-23 | 2004-11-24 | 株式会社日本製鋼所 | Magnesium alloys and magnesium alloy members with excellent corrosion resistance |
| JP3753101B2 (en) * | 2002-07-03 | 2006-03-08 | 住友金属工業株式会社 | High strength and high rigidity steel and manufacturing method thereof |
| JP4213021B2 (en) * | 2003-11-25 | 2009-01-21 | 愛知製鋼株式会社 | High rigidity steel with excellent machinability |
| JP4172424B2 (en) * | 2004-05-27 | 2008-10-29 | 住友金属工業株式会社 | Hot-rolled steel material and manufacturing method thereof |
-
2006
- 2006-09-06 EP EP06291413A patent/EP1897963A1/en not_active Withdrawn
-
2007
- 2007-08-27 MX MX2009002411A patent/MX2009002411A/en active IP Right Grant
- 2007-08-27 ES ES07823448.1T patent/ES2659987T3/en active Active
- 2007-08-27 KR KR1020097004737A patent/KR20090043555A/en active Search and Examination
- 2007-08-27 RU RU2009108338/02A patent/RU2416671C2/en active
- 2007-08-27 CA CA2662741A patent/CA2662741C/en active Active
- 2007-08-27 BR BRPI0716877A patent/BRPI0716877B1/en active IP Right Grant
- 2007-08-27 WO PCT/FR2007/001401 patent/WO2008029011A2/en active Application Filing
- 2007-08-27 UA UAA200902135A patent/UA95490C2/en unknown
- 2007-08-27 HU HUE07823448A patent/HUE036845T2/en unknown
- 2007-08-27 CN CN2007800330419A patent/CN101563476B/en active Active
- 2007-08-27 TR TR2018/02707T patent/TR201802707T4/en unknown
- 2007-08-27 JP JP2009527173A patent/JP5298017B2/en active Active
- 2007-08-27 EP EP07823448.1A patent/EP2064360B1/en active Active
- 2007-08-27 PL PL07823448T patent/PL2064360T3/en unknown
-
2009
- 2009-02-26 ZA ZA2009/01377A patent/ZA200901377B/en unknown
- 2009-03-03 MA MA31679A patent/MA30698B1/en unknown
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR3114447A1 (en) * | 2020-09-24 | 2022-03-25 | Constellium Neuf-Brisach | STEEL BATTERY BOTTOM FOR ELECTRIC VEHICLES |
| WO2022064148A1 (en) * | 2020-09-24 | 2022-03-31 | Constellium Neuf-Brisach | Bottom of steel battery trays for electric vehicles |
Also Published As
| Publication number | Publication date |
|---|---|
| MX2009002411A (en) | 2009-03-20 |
| WO2008029011A2 (en) | 2008-03-13 |
| CN101563476B (en) | 2011-11-16 |
| WO2008029011A3 (en) | 2008-05-02 |
| ZA200901377B (en) | 2009-12-30 |
| KR20090043555A (en) | 2009-05-06 |
| CA2662741A1 (en) | 2008-03-13 |
| EP2064360A2 (en) | 2009-06-03 |
| HUE036845T2 (en) | 2018-08-28 |
| PL2064360T3 (en) | 2018-06-29 |
| ES2659987T3 (en) | 2018-03-20 |
| RU2009108338A (en) | 2010-09-20 |
| TR201802707T4 (en) | 2018-03-21 |
| RU2416671C2 (en) | 2011-04-20 |
| CA2662741C (en) | 2012-02-07 |
| MA30698B1 (en) | 2009-09-01 |
| JP2010502838A (en) | 2010-01-28 |
| BRPI0716877B1 (en) | 2017-05-02 |
| EP1897963A1 (en) | 2008-03-12 |
| JP5298017B2 (en) | 2013-09-25 |
| BRPI0716877A2 (en) | 2013-10-15 |
| CN101563476A (en) | 2009-10-21 |
| UA95490C2 (en) | 2011-08-10 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP2064360B1 (en) | Steel sheet for the manufacture of light structures and manufacturing process of this sheet | |
| US10702916B2 (en) | Steel plate for producing light structures and method for producing said plate | |
| EP1844173B1 (en) | Method for producing austenitic iron-carbon-manganese metal sheets, and sheets produced thereby | |
| EP1913169B1 (en) | Manufacture of steel sheets having high resistance and excellent ductility, products thereof | |
| EP1649069B1 (en) | Method of producing austenitic iron/carbon/manganese steel sheets having a high strength and excellent toughness and being suitable for cold forming, and sheets thus produced | |
| EP2155916B1 (en) | Low density steel with good stamping capability | |
| EP2171112A1 (en) | Method for producing steel sheets having high resistance and ductility characteristics, and sheets thus obtained | |
| WO2012153009A1 (en) | Method for the production of very-high-strength martensitic steel and sheet thus obtained | |
| EP3411508B1 (en) | Thick al - cu - li - alloy sheets having improved fatigue properties | |
| EP0460234B1 (en) | Sheet of titanium-aluminum intermetallic compound and process for producing the same | |
| EP1379706B1 (en) | Tool steel having high toughness, method for producing parts made of said steel, and parts thus obtained | |
| EP2257652B1 (en) | Method of manufacturing sheets of austenitic stainless steel with high mechanical properties | |
| FR2665461A1 (en) | High tenacity non-refined steels and method for manufacturing them | |
| EP3274483A1 (en) | Parts with a bainitic structure having high strength properties and manufacturing process | |
| JP4418115B2 (en) | High-strength steel with excellent toughness of laser welds |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
| 17P | Request for examination filed |
Effective date: 20090406 |
|
| AK | Designated contracting states |
Kind code of ref document: A2 Designated state(s): AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LI LT LU LV MC MT NL PL PT RO SE SI SK TR |
|
| AX | Request for extension of the european patent |
Extension state: AL BA HR MK RS |
|
| DAX | Request for extension of the european patent (deleted) | ||
| RAP1 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: ARCELORMITTAL |
|
| 17Q | First examination report despatched |
Effective date: 20160527 |
|
| REG | Reference to a national code |
Ref country code: DE Ref legal event code: R079 Ref document number: 602007053560 Country of ref document: DE Free format text: PREVIOUS MAIN CLASS: C22C0038000000 Ipc: C22C0038020000 |
|
| RIC1 | Information provided on ipc code assigned before grant |
Ipc: C22C 38/02 20060101AFI20170531BHEP Ipc: C22C 38/14 20060101ALI20170531BHEP |
|
| GRAP | Despatch of communication of intention to grant a patent |
Free format text: ORIGINAL CODE: EPIDOSNIGR1 |
|
| INTG | Intention to grant announced |
Effective date: 20170905 |
|
| GRAS | Grant fee paid |
Free format text: ORIGINAL CODE: EPIDOSNIGR3 |
|
| GRAA | (expected) grant |
Free format text: ORIGINAL CODE: 0009210 |
|
| AK | Designated contracting states |
Kind code of ref document: B1 Designated state(s): AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LI LT LU LV MC MT NL PL PT RO SE SI SK TR |
|
| REG | Reference to a national code |
Ref country code: GB Ref legal event code: FG4D Free format text: NOT ENGLISH |
|
| REG | Reference to a national code |
Ref country code: CH Ref legal event code: EP |
|
| REG | Reference to a national code |
Ref country code: AT Ref legal event code: REF Ref document number: 958363 Country of ref document: AT Kind code of ref document: T Effective date: 20180115 |
|
| REG | Reference to a national code |
Ref country code: IE Ref legal event code: FG4D Free format text: LANGUAGE OF EP DOCUMENT: FRENCH |
|
| REG | Reference to a national code |
Ref country code: DE Ref legal event code: R096 Ref document number: 602007053560 Country of ref document: DE |
|
| REG | Reference to a national code |
Ref country code: RO Ref legal event code: EPE Ref country code: SE Ref legal event code: TRGR |
|
| REG | Reference to a national code |
Ref country code: ES Ref legal event code: FG2A Ref document number: 2659987 Country of ref document: ES Kind code of ref document: T3 Effective date: 20180320 |
|
| REG | Reference to a national code |
Ref country code: NL Ref legal event code: FP |
|
| PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: LT Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20171227 |
|
| REG | Reference to a national code |
Ref country code: LT Ref legal event code: MG4D |
|
| PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: LV Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20171227 Ref country code: GR Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20180328 Ref country code: BG Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20180327 |
|
| REG | Reference to a national code |
Ref country code: SK Ref legal event code: T3 Ref document number: E 26974 Country of ref document: SK |
|
| REG | Reference to a national code |
Ref country code: FR Ref legal event code: PLFP Year of fee payment: 12 |
|
| PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: CY Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20171227 Ref country code: EE Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20171227 |
|
| REG | Reference to a national code |
Ref country code: HU Ref legal event code: AG4A Ref document number: E036845 Country of ref document: HU |
|
| PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: IS Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20180427 |
|
| PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: MT Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20171227 |
|
| REG | Reference to a national code |
Ref country code: DE Ref legal event code: R097 Ref document number: 602007053560 Country of ref document: DE |
|
| PLBE | No opposition filed within time limit |
Free format text: ORIGINAL CODE: 0009261 |
|
| STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT |
|
| PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: DK Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20171227 |
|
| 26N | No opposition filed |
Effective date: 20180928 |
|
| PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: SI Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20171227 |
|
| PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: MC Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20171227 |
|
| REG | Reference to a national code |
Ref country code: CH Ref legal event code: PL |
|
| PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: CH Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20180831 Ref country code: LI Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20180831 Ref country code: LU Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20180827 |
|
| PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: PT Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20171227 |
|
| PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: IE Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20180827 |
|
| REG | Reference to a national code |
Ref country code: AT Ref legal event code: UEP Ref document number: 958363 Country of ref document: AT Kind code of ref document: T Effective date: 20171227 |
|
| P01 | Opt-out of the competence of the unified patent court (upc) registered |
Effective date: 20230427 |
|
| PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: NL Payment date: 20230721 Year of fee payment: 17 |
|
| PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: TR Payment date: 20230727 Year of fee payment: 17 Ref country code: RO Payment date: 20230731 Year of fee payment: 17 Ref country code: IT Payment date: 20230720 Year of fee payment: 17 Ref country code: GB Payment date: 20230720 Year of fee payment: 17 Ref country code: FI Payment date: 20230720 Year of fee payment: 17 Ref country code: ES Payment date: 20230901 Year of fee payment: 17 Ref country code: CZ Payment date: 20230725 Year of fee payment: 17 Ref country code: AT Payment date: 20230721 Year of fee payment: 17 |
|
| PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: SK Payment date: 20230727 Year of fee payment: 17 Ref country code: SE Payment date: 20230720 Year of fee payment: 17 Ref country code: PL Payment date: 20230721 Year of fee payment: 17 Ref country code: HU Payment date: 20230803 Year of fee payment: 17 Ref country code: FR Payment date: 20230720 Year of fee payment: 17 Ref country code: DE Payment date: 20230720 Year of fee payment: 17 Ref country code: BE Payment date: 20230720 Year of fee payment: 17 |