WO2002000956A1 - Composition et procede destines a la fabrication d'aciers multiphases - Google Patents
Composition et procede destines a la fabrication d'aciers multiphases Download PDFInfo
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- WO2002000956A1 WO2002000956A1 PCT/ES2000/000225 ES0000225W WO0200956A1 WO 2002000956 A1 WO2002000956 A1 WO 2002000956A1 ES 0000225 W ES0000225 W ES 0000225W WO 0200956 A1 WO0200956 A1 WO 0200956A1
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- WIPO (PCT)
- Prior art keywords
- steel
- maximum
- composition
- temperature
- mpa
- Prior art date
Links
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 133
- 239000010959 steel Substances 0.000 title claims abstract description 133
- 239000000203 mixture Substances 0.000 title claims abstract description 58
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 29
- 238000000034 method Methods 0.000 title claims description 30
- 238000011282 treatment Methods 0.000 claims abstract description 26
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 22
- 230000000930 thermomechanical effect Effects 0.000 claims abstract description 18
- 238000000137 annealing Methods 0.000 claims abstract description 17
- 229910052742 iron Inorganic materials 0.000 claims abstract description 11
- 239000012535 impurity Substances 0.000 claims abstract description 8
- 229910000734 martensite Inorganic materials 0.000 claims description 27
- 229910001563 bainite Inorganic materials 0.000 claims description 19
- 239000010936 titanium Substances 0.000 claims description 18
- 239000010955 niobium Substances 0.000 claims description 17
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 16
- 239000011159 matrix material Substances 0.000 claims description 16
- 238000005246 galvanizing Methods 0.000 claims description 14
- 239000011572 manganese Substances 0.000 claims description 13
- 238000005097 cold rolling Methods 0.000 claims description 12
- 238000001816 cooling Methods 0.000 claims description 12
- 230000009467 reduction Effects 0.000 claims description 12
- 229910000859 α-Fe Inorganic materials 0.000 claims description 12
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 11
- 229910052719 titanium Inorganic materials 0.000 claims description 11
- 238000005098 hot rolling Methods 0.000 claims description 10
- 229910052758 niobium Inorganic materials 0.000 claims description 10
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 claims description 10
- 229910001297 Zn alloy Inorganic materials 0.000 claims description 9
- 229910052757 nitrogen Inorganic materials 0.000 claims description 9
- 229910052710 silicon Inorganic materials 0.000 claims description 9
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 8
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 8
- 229910052782 aluminium Inorganic materials 0.000 claims description 8
- 229910001566 austenite Inorganic materials 0.000 claims description 8
- 229910052799 carbon Inorganic materials 0.000 claims description 8
- KFZAUHNPPZCSCR-UHFFFAOYSA-N iron zinc Chemical compound [Fe].[Zn] KFZAUHNPPZCSCR-UHFFFAOYSA-N 0.000 claims description 8
- 239000010703 silicon Substances 0.000 claims description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 7
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims description 7
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 7
- 229910052748 manganese Inorganic materials 0.000 claims description 7
- 229910052750 molybdenum Inorganic materials 0.000 claims description 7
- 239000011733 molybdenum Substances 0.000 claims description 7
- 229910052698 phosphorus Inorganic materials 0.000 claims description 7
- 230000000717 retained effect Effects 0.000 claims description 7
- 238000005096 rolling process Methods 0.000 claims description 7
- 229910052717 sulfur Inorganic materials 0.000 claims description 7
- 239000011593 sulfur Substances 0.000 claims description 7
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 6
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims description 6
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 6
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 6
- 229910052796 boron Inorganic materials 0.000 claims description 6
- 239000011574 phosphorus Substances 0.000 claims description 6
- 239000000126 substance Substances 0.000 claims description 6
- 239000011701 zinc Substances 0.000 claims description 6
- 229910052725 zinc Inorganic materials 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 5
- 238000004804 winding Methods 0.000 claims description 4
- 238000009628 steelmaking Methods 0.000 claims description 3
- 238000009864 tensile test Methods 0.000 claims description 2
- 238000007598 dipping method Methods 0.000 claims 3
- 238000002791 soaking Methods 0.000 claims 3
- 239000010960 cold rolled steel Substances 0.000 claims 2
- 230000008569 process Effects 0.000 description 14
- 230000015572 biosynthetic process Effects 0.000 description 8
- 230000000694 effects Effects 0.000 description 8
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 229910052760 oxygen Inorganic materials 0.000 description 6
- 239000001301 oxygen Substances 0.000 description 6
- 238000001000 micrograph Methods 0.000 description 5
- 239000000047 product Substances 0.000 description 5
- 238000007796 conventional method Methods 0.000 description 4
- 238000003475 lamination Methods 0.000 description 4
- 238000005272 metallurgy Methods 0.000 description 4
- 239000004848 polyfunctional curative Substances 0.000 description 4
- 238000009749 continuous casting Methods 0.000 description 3
- 238000002347 injection Methods 0.000 description 3
- 239000007924 injection Substances 0.000 description 3
- 150000001247 metal acetylides Chemical class 0.000 description 3
- 150000004767 nitrides Chemical class 0.000 description 3
- 239000010451 perlite Substances 0.000 description 3
- 235000019362 perlite Nutrition 0.000 description 3
- 239000002244 precipitate Substances 0.000 description 3
- 238000005204 segregation Methods 0.000 description 3
- 150000004763 sulfides Chemical class 0.000 description 3
- 230000009466 transformation Effects 0.000 description 3
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 2
- 230000032683 aging Effects 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- 229910052791 calcium Inorganic materials 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000001934 delay Effects 0.000 description 2
- 238000006477 desulfuration reaction Methods 0.000 description 2
- 230000023556 desulfurization Effects 0.000 description 2
- 230000005496 eutectics Effects 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 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 2
- 239000006104 solid solution Substances 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 229910001018 Cast iron Inorganic materials 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 229940043430 calcium compound Drugs 0.000 description 1
- 150000001674 calcium compounds Chemical class 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 229910001353 gamma loop Inorganic materials 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 239000003112 inhibitor Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- VCTOKJRTAUILIH-UHFFFAOYSA-N manganese(2+);sulfide Chemical class [S-2].[Mn+2] VCTOKJRTAUILIH-UHFFFAOYSA-N 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
- 238000003303 reheating Methods 0.000 description 1
- 229910052702 rhenium Inorganic materials 0.000 description 1
- 238000010583 slow cooling Methods 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000005482 strain hardening Methods 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
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
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
- C23C2/022—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by heating
- C23C2/0224—Two or more thermal pretreatments
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
- C23C2/024—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by cleaning or etching
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0236—Cold rolling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0273—Final recrystallisation annealing
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0278—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips involving a particular surface treatment
Definitions
- the invention relates, in general, to the manufacture of steels with complex phase of high strength and ductility and, in particular, to a composition useful for manufacturing such steels, with varying final qualities and to the process for their manufacture which comprises subjecting said composition to a predetermined ter omecanic treatment throughout its production process.
- This type of steel falls within the so-called ultifase steels whose microstructure is formed by a ferritic matrix as the majority phase and bainite and martensite as minority dispersed phases, with ratios with respect to the ferrite of 0-25% and 4-
- Bainite and martensite, very hard phases give the steel a high mechanical resistance while ferrite is responsible for the ductility of the material. Additionally, the three phases are hardened by different types of precipitates, primarily niobium and titanium. Additionally, a dispersed phase of retained austenite may appear at room temperature.
- the invention provides a composition suitable for the manufacture of different firm qualities of high strength multiphase steels, by applying different thermomechanical treatments on said composition.
- the invention also provides methods for manufacturing said multi-phase steels of various qualities comprising the use of said composition and the application of an appropriate thermomechanical treatment.
- the invention has the advantage that multiphase steels of various qualities can be obtained from the same composition by varying only the thermomechanical treatment.
- multiphase steels can be obtained that have the following characteristics:
- the band can be electrocoated WH + BH> 100 MPa where H represents work hardening and BH represents bake hardening.
- the band can be subdued in the line of galvanized to an iron-zinc alloy (galvannneal) treatment at 480-500 ° C
- Figure 1 is a micrograph of a multiphase steel provided by this invention, obtained by cold rolling and bell annealing [see Example 3].
- Figure 2 is a micrograph of a multiphase steel provided by this invention, obtained by cold rolling, bell annealing and hot dipped galvanizing [see Example 4].
- Figure 3 is a micrograph of a multiphase steel provided by this invention obtained by cold rolling, bell annealing and hot dip galvanizing [see Example 4] with iron-zinc alloy treatment.
- Figure 4 is a micrograph of a multiphase steel provided by this invention, obtained by cold rolling and hot dipped galvanizing [see Example 5].
- Figure 5 is a micrograph of a multiphase steel provided by this invention, obtained by cold rolling and hot dipped galvanizing [see Example 5].
- Figure 6 corresponds to a graph summarizing the typical properties of all the processes and products of this invention.
- composition of the invention comprising the following elementary composition, in weight percent:
- Carbon This is the hardening element by excellence in steel. It has a great affinity with other elements such as titanium, niobium and vanadium, forming very hard carbides that also inhibit the growth of grain. If the content is less than 0.04% these effects do not occur or at least in the appropriate proportion. On the contrary, if the content exceeds 0.13%, cracks may appear when cooling both in hot rolling and in subsequent heating-cooling processes, as well as a loss of ductility and an increase in the fragility of the steel. Additionally, the welding process is difficult.
- Manganese It is a ferrite hardener. In the absence of manganese, sulfur combines with iron forming sulfides, giving rise to an eutectic that surrounds the primary grains. This, at the lamination temperature, melts leaving the grains unlinked and very weak, which could cause breakage when hot. Another very interesting effect is to increase the gamma loop by delaying the formation of perlite, very harmful in this type of steels. In this sense, a minimum of 1% of this element and a maximum of 2.1% are set, since above this value there is a risk of segregation in continuous casting and surface problems during hot galvanizing.
- Silicon It is also a ferrite hardener but, on the other hand, excessive content can lead to surface quality problems during galvanization, so its content is limited to 0.3%.
- Sulfur In most steel applications it is considered an undesirable and harmful element. Due to its affinity with iron and with the manganese, it forms sulfides, which, being soluble with each other, form a eutectic with a lower melting point than that of steel, so they will always concentrate on the last portion of solidified steel
- Phosphorus This is another hardener element of the ferrite by solid solution. In this particular application it is limited to 0.025% maximum to avoid problems of fragility in the hot rolled material.
- Aluminum Like silicon, it is a strong deoxidizer, as well as an inhibitor of carbide formation. It has great avidity for nitrogen with which it forms nitrides that can function as grain size tuners. The lower limit is determined by the minimum amount necessary to ensure complete deoxidation and uptake of the nitrogen present in the steel and capable of causing aging phenomena. A content greater than 0.1% would result in an extra cost without providing quality improvements.
- Nitrogen It is a very difficult element to remove from steel, so you always try to combine with aluminum For the reasons stated. It is, together with carbon, one of the main responsible for the aging of steels and an excess content can cause cold fragility. In view of the above, the maximum content is set at 0.009%.
- Niobium It is a great grain tuner in hot rolling. Niobium carbonitrides precipitate during lamination delaying recrystallization and resulting in sour austenite grains in the last lamination passes. This results in a greater inductive force for the transformation of austenite into ferrite, favoring its formation. Another important effect is the increase in steel resistance by precipitation. For these effects to materialize, the minimum limit will be 0.01%. On the contrary, if it exceeds 0.1%, there is a risk that micro-cracks will occur in the area thermally affected by welding.
- Titanium This is another hardening element and grain tuner by formation of nitrides and / or carbides. These nitrides are less fragile than aluminum. In addition, titanium delays the formation of perlite. Below 0.01% these effects practically do not occur, while above 0.1% inclusions of titanium cyanonitride can be formed which are fatal for steels dedicated to structural uses.
- Molybdenum It is a great ferrite hardener by solid solution. This element gives the steels of High strength good toughness characteristics. Molybdenum delays perlitic transformation, favoring the hardenability of steel. With contents higher than 0.8%, cracks in the weld can be nuclear resulting in a deterioration of the toughness in the thermally affected area.
- Calcium which controls the shape of the oxides and the amount of sulfides, inevitably present in the steelmaking, and if left unchecked, the effects on fatigue and fragility can be very negative . Calcium must be added in the spoon desulfurization processes.
- composition having the following elementary composition, by weight:
- the composition of the invention can be obtained by conventional methods known to those skilled in the art. In the case at hand, it has been carried out in an oxygen conversion mill. It is based on cast iron of blast furnace, scrap and scorching elements that are tuned by blowing oxygen in a converter. Subsequently, a fine adjustment of the composition is carried out in the secondary metallurgy process in which desulfurization is included by adding calcium compounds. Finally the steel is solidified during the continuous casting stage.
- composition of the invention can be used in the manufacture of multiphase steels, for example, high strength, weldable, high ductility multiphase steels, and hot or cold rolled, both coated (galvanized or electroplated) eats uncoated.
- the different final qualities can be manufactured from the same composition of the invention by varying only the thermomechanical treatment verified by the coil throughout its process of production.
- the multi-phase steels, or complex phase are steels whose microstructure is formed by a ferritic matrix, as a majority phase, and bainite and martensite, as minority dispersed phases, with ratios with respect to the ferrite of 0-25% and 4- 25%, by volume, respectively. Bainite and martensite, very hard phases, give the steel a high mechanical resistance while ferrite is responsible for the ductility of the material. Additionally, the three phases are hardened by different types of precipitates, mainly of niobium and titanium. Additionally, a dispersed phase of retained austenite can appear in a proportion of 2-10% by volume that gives the product greater ductility by means of a mechanism known as TRIP (Transformation Induced Plasticity).
- TRIP Transformation Induced Plasticity
- the invention also provides a process for the manufacture of multi-phase steels comprising subjecting a composition of the invention to an appropriate thermomechanical treatment.
- said thermomechanical treatment is selected from (i) hot rolled strip, (ii) cold rolled and bell annealed strip, (iii) cold rolled strip, bell annealed and hot dipped galvanized; and (iv) cold rolled and hot dipped galvanized strip.
- Hot rolled strip Starting from a steel having a composition of the invention, hot coil qualities can be achieved with the appropriate parameter control. These should already be considered from the steelmaking process, which is of the utmost importance to achieve a clean steel from an inclusive point of view, free of internal or external segregations and cracks. Thereafter, hot rolling is carried out, with a preheating of the slabs at temperatures higher than 1,250 ° C in order to dissolve the microalloying carbides or carbonitrides in general.
- the first phase is the roughing, where the thickness of the roughing is reduced more than 6 times, with a tight temperature control, while in the second phase, carried out in the finishing train, it is where the thickness is achieved and width requested by the customer.
- the final lamination temperature must be between 850 ° C and 950 ° C.
- the last thermomechanical treatment that remains is controlled cooling to the winding temperature set between 400 ° C and 600 ° C, which will contribute greatly to the formation of the desired phase content.
- the resulting steel has a ferritic matrix with bainite and martensite as dispersed phases.
- This steel is hot dip galvanizable and can be welded by conventional methods without any special problems.
- Example 2 illustrates the manufacture of a multiphase steel by hot rolled strip. Trio laminated and bell annealed band
- the steel In the hot rolling process, the steel is rolled at a temperature above 850 ° C and wound in the range of 630 ° C to 730 ° C.
- the structure obtained in the hot rolled strip is ferritic matrix with bainite and martensite as a dispersed phase.
- the steel is cold rolled with a reduction greater than 40%.
- this material has, in hot coil, an elastic limit higher than other types of steels, its hardening by cold rolling is much less pronounced, almost equalizing its resistance with that of microalloyed steels for reductions of 70%.
- the cold rolled material is subjected to annealing in a conventional hood empapa Terms temperature in the range between 650 ° C and 700 ° C under H 2 or NH x.
- the resulting steel has a ferritic matrix structure with bainite and martensite as dispersed phases.
- the steel recrystallizes completely in the bell annealing furnace resulting in an equiaxial ferritic grain.
- Example 3 illustrates the manufacture of a multiphase steel by cold rolled strip.
- the resulting steel presents an microstructure formed by ferrite as the majority phase and martensite in a proportion of 15-25% by volume.
- the resulting structure has a ferritic matrix with dispersed phases of bainite, martensite and retained austenite, totaling 15 % to 25% by volume, of which the retained austenite is between 2 and 10%.
- Example 4 illustrates the manufacture of a multiphase steel by cold rolled strip, bell-annealed and hot dipped galvanized which can be followed by an iron-zinc alloy process.
- Cold rolled and hot dipped galvanized strip In the hot rolling process, the steel is rolled at a temperature above 850 ° C and wound in the range of 630 ° C to 730 ° C.
- the structure obtained in the hot rolled strip is ferritic matrix with bainite and martensite as a dispersed phase.
- the steel is cold rolled with a reduction greater than 40%. Although this material presents, in hot coil, an elastic limit superior to other types of steels, its hardening by cold rolling is much less pronounced, almost similar to microalloyed steels its resistance to 70% reductions.
- the band is heated in a continuous galvanizing line at a temperature between 700 ° C and 850 C C.
- the band is then cooled to the temperature of entry into the zinc bath, with speeds in the range between 5 and 60 ° C / s.
- the temperatures of the zinc bath are between 450 ° C and 490 ° C.
- Slow cooling is also allowed up to a temperature of 650 ° C, prior to rapid cooling, without any risk of perlite formation.
- iron-zinc alloy treatment between 480 ° C and 500 ° C can be subjected to the band, obtaining equal or superior properties.
- Example 5 illustrates the manufacture of a multi-phase steel by cold rolled and hot dipped galvanized strip.
- composition suitable for manufacturing multi-phase steels has been manufactured using different thermomechanical treatments.
- Said composition has the following elementary composition, by weight:
- a steel with a chemical composition such as that mentioned in Example 1 is subjected to a hot rolled strip process.
- the steel leaves the reheating furnaces at a temperature of 1,260 ° C with a roughing thickness of 250 mm.
- phase I a grinding
- the thickness is reduced to 40 mm, achieving in step 2 to a final rolling temperature of 900 ° C to a thickness of 3 mm.
- An average winding temperature of 530 ° C was reached on the cooling table.
- the average characteristics obtained were 720 MPa for the elastic limit (Re) and 930 MPa for the breaking load (Rm), with elongations (A) of 16% in proportional test tube.
- the resulting steel has a ferritic matrix structure with a percentage of bainite of 4.7% and martensite of 14.4% by volume.
- the steel was annealed in a bell furnace with NHx atmosphere (95%. N 2 , 5% H 2 ) with an average heating rate of 35 ° C / h to a temperature of 680 ° C, at which it was maintained for 8 h, being subsequently cooled to room temperature at an average speed of 35 ° C / h.
- NHx atmosphere 95%. N 2 , 5% H 2
- the resulting steel has a ferritic matrix being the bainite and martensite phases dispersed with ratios of
- the ferritic grain size is approximately 12 ASTM [see Figure
- the resulting steel has the following mechanical properties: Re 0.2%: 383 MPa
- the steel has no creep shield and can be electrocoated.
- the band can be welded using traditional methods.
- the steel was annealed in a bell furnace with an NHx atmosphere (95% N 2 , 5% H 2 ) with an average heating rate of 35 ° C / h to a temperature of 680 ° C at which it was maintained for 8 h, being subsequently cooled to room temperature at an average speed of 35 ° C / h.
- NHx atmosphere 95% N 2 , 5% H 2
- the band is heated again in a galvanizing line by performing one of the following treatments:
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Abstract
Priority Applications (2)
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AU2000254082A AU2000254082A1 (en) | 2000-06-26 | 2000-06-26 | Composition and method for the production of multiphase steels |
PCT/ES2000/000225 WO2002000956A1 (fr) | 2000-06-26 | 2000-06-26 | Composition et procede destines a la fabrication d'aciers multiphases |
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PCT/ES2000/000225 WO2002000956A1 (fr) | 2000-06-26 | 2000-06-26 | Composition et procede destines a la fabrication d'aciers multiphases |
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PCT/ES2000/000225 WO2002000956A1 (fr) | 2000-06-26 | 2000-06-26 | Composition et procede destines a la fabrication d'aciers multiphases |
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Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2209926A4 (fr) * | 2007-10-10 | 2016-10-19 | Nucor Corp | Acier à structure métallographique complexe et son procédé de fabrication |
CN114318143A (zh) * | 2021-12-22 | 2022-04-12 | 河钢股份有限公司承德分公司 | 一种厚规格无花热镀锌钢卷及其制备方法 |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0510718A2 (fr) * | 1991-04-26 | 1992-10-28 | Kawasaki Steel Corporation | Tôle en acier à haute résistance, laminée à froid, inaltérable à température ambiante et ayant l'aptitude à l'emboutissage profond et procédé de fabrication |
EP0528407A1 (fr) * | 1991-08-19 | 1993-02-24 | Kawasaki Steel Corporation | Tôles d'acier laminées à froid ayant une tenacité élevée et une bonne aptitude à l'emboutissage profond |
EP0753596A1 (fr) * | 1995-01-26 | 1997-01-15 | Nippon Steel Corporation | Acier soudable de haute resistance ayant une durete excellente a basse temperature |
EP0757113A1 (fr) * | 1995-02-03 | 1997-02-05 | Nippon Steel Corporation | Acier de canalisation extremement resistant possedant un rapport d'ecoulement peu eleve et une excellente resistance a basse temperature |
-
2000
- 2000-06-26 WO PCT/ES2000/000225 patent/WO2002000956A1/fr active Application Filing
- 2000-06-26 AU AU2000254082A patent/AU2000254082A1/en not_active Abandoned
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0510718A2 (fr) * | 1991-04-26 | 1992-10-28 | Kawasaki Steel Corporation | Tôle en acier à haute résistance, laminée à froid, inaltérable à température ambiante et ayant l'aptitude à l'emboutissage profond et procédé de fabrication |
EP0528407A1 (fr) * | 1991-08-19 | 1993-02-24 | Kawasaki Steel Corporation | Tôles d'acier laminées à froid ayant une tenacité élevée et une bonne aptitude à l'emboutissage profond |
EP0753596A1 (fr) * | 1995-01-26 | 1997-01-15 | Nippon Steel Corporation | Acier soudable de haute resistance ayant une durete excellente a basse temperature |
EP0757113A1 (fr) * | 1995-02-03 | 1997-02-05 | Nippon Steel Corporation | Acier de canalisation extremement resistant possedant un rapport d'ecoulement peu eleve et une excellente resistance a basse temperature |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2209926A4 (fr) * | 2007-10-10 | 2016-10-19 | Nucor Corp | Acier à structure métallographique complexe et son procédé de fabrication |
CN114318143A (zh) * | 2021-12-22 | 2022-04-12 | 河钢股份有限公司承德分公司 | 一种厚规格无花热镀锌钢卷及其制备方法 |
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AU2000254082A1 (en) | 2002-01-08 |
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