EP0988901B1 - Manufacturing method for stainless steel thin strip - Google Patents
Manufacturing method for stainless steel thin strip Download PDFInfo
- Publication number
- EP0988901B1 EP0988901B1 EP99402235A EP99402235A EP0988901B1 EP 0988901 B1 EP0988901 B1 EP 0988901B1 EP 99402235 A EP99402235 A EP 99402235A EP 99402235 A EP99402235 A EP 99402235A EP 0988901 B1 EP0988901 B1 EP 0988901B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- strip
- rolling mill
- cylinders
- casting
- walls
- 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.)
- Revoked
Links
- 229910001220 stainless steel Inorganic materials 0.000 title claims abstract description 12
- 239000010935 stainless steel Substances 0.000 title claims abstract description 8
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 6
- 238000005266 casting Methods 0.000 claims abstract description 34
- 238000005096 rolling process Methods 0.000 claims abstract description 31
- 238000007711 solidification Methods 0.000 claims abstract description 15
- 230000008023 solidification Effects 0.000 claims abstract description 15
- 239000007788 liquid Substances 0.000 claims abstract description 9
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 8
- 239000010959 steel Substances 0.000 claims abstract description 8
- 238000005098 hot rolling Methods 0.000 claims description 18
- 238000000034 method Methods 0.000 claims description 8
- 229910052799 carbon Inorganic materials 0.000 claims description 3
- 230000033001 locomotion Effects 0.000 claims description 3
- 238000009434 installation Methods 0.000 abstract description 10
- 238000003475 lamination Methods 0.000 abstract description 2
- 238000010030 laminating Methods 0.000 abstract 1
- 238000003466 welding Methods 0.000 description 10
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 229910001338 liquidmetal Inorganic materials 0.000 description 5
- 238000003303 reheating Methods 0.000 description 4
- 238000004804 winding Methods 0.000 description 4
- 208000035126 Facies Diseases 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 2
- 238000012512 characterization method Methods 0.000 description 2
- 230000008602 contraction Effects 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000006731 degradation reaction Methods 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000005554 pickling Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000009864 tensile test Methods 0.000 description 2
- 239000010936 titanium Substances 0.000 description 2
- 229910052719 titanium Inorganic materials 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 230000003466 anti-cipated effect Effects 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 238000005097 cold rolling Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000001143 conditioned effect Effects 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000011572 manganese Substances 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 239000010955 niobium Substances 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 235000011837 pasties Nutrition 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 238000010405 reoxidation reaction Methods 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 238000000844 transformation Methods 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/46—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/40—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling foils which present special problems, e.g. because of thinness
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/46—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting
- B21B1/463—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting in a continuous process, i.e. the cast not being cut before rolling
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/46—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting
- B21B1/466—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting in a non-continuous process, i.e. the cast being cut before rolling
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
- B21B3/02—Rolling special iron alloys, e.g. stainless steel
Definitions
- the invention relates to the manufacture of thin strips of stainless steel, directly from liquid metal, by solidification inside an ingot mold consisting of two cooled walls moving at the same speed as the solidified strip, such as the outer walls of two rotating cylinders with horizontal axes.
- the causes of the appearance of these porosities at the heart of the bands cast between cylinders can be similar to those that cause (on a dimensional scale upper) the shrinkage in the ingots and the central porosities in the products of classic continuous casting, namely the closure of pockets containing solid metal still liquid metal when the solidification of the product (which normally is substantially completed when the strip leaves the walls of the ingot mold, i.e. the core of the strip is no longer completely in the liquid state) is not carried out completely regularly.
- the cooling and solidification of the liquid metal that enclose these pockets are accompanied by a contraction of this metal, which causes a empty space. This can not be filled before the end of solidification, because this pocket closed is no longer fed by new liquid metal.
- These porosities must be distinguished from spherical faults called "blowing" which are due to a release of gas dissolved and most often occur near the surface of products.
- Document EP 0 396 862 proposes a process aimed at eliminating the porosities central, and also other internal and superficial defects, when casting strips of steel between two cylinders.
- the casting rolls have on their surfaces of the circumferential grooves precisely dimensioned, and arranged in offset on the two cylinders.
- the only prevention of these detachments is insufficient to completely avoid the appearance of central porosities.
- the object of the invention is to propose a method guaranteeing closure final of the central porosities appeared in the core of the strip after its solidification complete.
- the subject of the invention is a method for manufacturing a thin strip.
- stainless steel by direct solidification of the liquid steel in the form of a strip of thickness less than or equal to 8 mm in a casting installation comprising two cooled walls in movement and by hot rolling of said strip, the solidification is substantially completed when it leaves said walls, characterized in what hot rolling is done on a rolling mill whose working rolls have a diameter between 400 and 900 mm, in that the temperature of the strip on leaving the rolling mill is between 800 and 1100 ° C, and in that the rate of thickness reduction of the strip during hot rolling is between 15 and 50%.
- the hot rolling is carried out in line with the casting of the bandaged.
- the casting installation can be of the “casting between cylinders” type.
- the object of the invention is achieved by the combination requirements relating to the diameter of the working rolls of the hot rolling mill, the temperature of the strip at its exit from the cylinders and the rate of reduction of the thickness of the strip during hot rolling.
- the invention applies to the casting of stainless steels of all classes, which have conventionally carbon contents less than or equal to 1%, silicon contents less than or equal to 1%, manganese contents less than or equal to 15%, chromium contents between 10 and 30%, copper contents less than or equal to 5% and nitrogen contents less than or equal to 0.5% (these contents are expressed in weight percentages).
- These steels can also contain significant quantities nickel (up to 40%) or molybdenum (up to 8%).
- impurities either as alloying elements, in particular sulfur, phosphorus, titanium, niobium, zirconium. Their total must not exceed 2% by weight.
- a thin strip of stainless steel poured between cylinders is highly likely to develop porosities in its heart, during its solidification, when a liquid pocket is closed with solid metal.
- This phenomenon occurs at the end of solidification of the pasty zone, also called “equiaxial zone”, located between the two skins solidified in contact with the cylinders, also called “columnar areas”.
- the area equiaxial is very difficult to control, and its thickness can vary depending on the speed of solidification of columnar areas.
- the equiaxial zone can close locally from anticipated, at levels where the growth of columnar areas has been faster than the normal.
- the liquid bags Downstream of the closing point of the equiaxial zone, the liquid bags do not can no longer be properly replenished with liquid metal, and porosities form by contraction of the metal during the solidification of these liquid pockets. This case remains nevertheless quite rare, and in fact, generally, the isolation of a liquid pocket occurs by the grouping in the liquid of equiaxial crystals which come to form a plug obstructing the equiaxial zone.
- the porosities which form in the equiaxial zone are consisting of sets of gas-free channels and cavities, the dimension of which maximum according to the thickness of the sheet corresponds to the thickness of the equiaxial zone (i.e. 100 at 400 ⁇ m), and which can reach a length of 1 to 2 mm in the other directions. As we said, it is not a spherical blow which would originate from a evolution of gas, or an internal fault opening on the surface of the strip.
- the idea behind the invention is to create, during the hot rolling of the strip solidified, conditions such that they lead not only to a closure of central porosities as it is already known, but also a real welding of opposite walls of the porosities, which the rolling made it possible to bring together. In this way, we ensures that the porosities are not likely to open during subsequent shaping of the strip or when using the products thus produced.
- hot rolling the strip two stages follow one another. First, the internal walls of the defect are gradually approach as the thickness of the strip decreases, until brought into contact. Then, once this contact has been made, the walls are welded produced by diffusion of the constituent elements of steel through the interface. But one efficient welding of the walls must already have been obtained before the exit of the strip the grip of the rolls of the rolling mill, because otherwise the relaxation of the compression of the strip which occurs at the outlet of the cylinders leads to a partial detachment of the walls.
- the efficiency of welding essentially depends on two parameters: the duration of the forced contact of the walls in the rolling mill and the temperature at which it takes place this contact.
- This forced contact must therefore take place as soon as possible after entry of the strip in the rolling mill, and its duration depends mainly, for a speed of given rolling (which is, in the case of in-line rolling, largely conditioned by the thickness of the strip before it is rolled), the diameter of the working rolls of the rolling mill and the reduction rate of its thickness which they impose on the strip.
- the cylinders have a very large diameter, the cooling of the strip which they cause risks leading it to a temperature insufficient for that the welding of the walls of the porosities can be complete.
- the value of the temperature of the strip as it leaves the cylinders provides a good indication of the actual possibility that the walls of the porosities had to weld to each other in the grip of the cylinders.
- the temperature of the strip at the outlet of the cylinders must therefore be sufficient to allow the welding of porosities, but it must not be too high either, so avoid excessive thermal load on the cylinders. This would lead to a degradation of their surface resulting in a deterioration of the surface appearance of the strip in the form of excessive roughness.
- the objective of the invention cannot therefore be achieved without getting annoying side effects for the overall quality of the tape that if we combine the diameter of the cylinders, the reduction rate and the temperature of the strip leaving the rolling mill adequately.
- Table 1 groups together the compositions of the steels on which the tests were carried out, the results of which are given in Table 2. The contents of the various elements are given in percentages by weight. Table 1 also gives the thicknesses at the outlet of the casting rolls of the strips on which the tests were carried out, as well as the corresponding casting speeds, measured between the casting rolls and the hot rolling mill.
- compositions of types A and A 'flows correspond to those of steels classic austenitic stainless steels type AISI 304.
- Type B castings correspond to AISI 430 type ferritic stainless steels.
- Type C castings correspond to AISI 409 ferritic stainless steels stabilized with titanium.
- Table 2 shows the results of tests carried out on the strips from these castings, with the corresponding test conditions. Results of tests carried out on types A, A ', B, C Field of the invention Type of casting Diameter of rolling mill rolls (mm) Reduction rate (%) Temperature of the strip leaving the rolling mill (° C) Welding of porosities Other faults no AT 300 50 1100 no nothingness no AT 400 10 1100 no nothingness no AT 400 15 750 no nothingness Yes A, A ', B, C 400 15 800 Yes nothingness Yes A, A ', B, C 400 15 1100 Yes nothingness no AT 400 15 1150 Yes too strong roughness no AT 400 50 750 no nothingness Yes A, A ', B, C 400 50 800 Yes nothingness Yes A, A ', B, C 400 50 1100 Yes nothingness no AT 400 50 1150 Yes too strong roughness no AT 400 60 1100 Yes critics no AT 900 10 1100 no nothingness no AT 900 15 750 no nothingness Yes A, A ', B, C 900 15 800 Yes nothing
- the invention applies not only to installations for casting between rolls, but to any other type of casting installation of thin strips of stainless steel between two cooled surfaces in motion, such as moving bands.
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Metal Rolling (AREA)
- Continuous Casting (AREA)
- Heat Treatment Of Sheet Steel (AREA)
- Physical Vapour Deposition (AREA)
- Chemical Treatment Of Metals (AREA)
- Chemical Vapour Deposition (AREA)
- Reduction Rolling/Reduction Stand/Operation Of Reduction Machine (AREA)
- Superconductors And Manufacturing Methods Therefor (AREA)
Abstract
Description
L'invention concerne la fabrication des bandes minces en acier inoxydable, directement à partir de métal liquide, par solidification à l'intérieur d'une lingotière constituée par deux parois refroidies se déplaçant à la même vitesse que la bande solidifiée, telles que les parois externes de deux cylindres en rotation à axes horizontaux.The invention relates to the manufacture of thin strips of stainless steel, directly from liquid metal, by solidification inside an ingot mold consisting of two cooled walls moving at the same speed as the solidified strip, such as the outer walls of two rotating cylinders with horizontal axes.
Dans ce procédé de coulée qui est en cours d'industrialisation sous le nom de « coulée entre cylindres », l'un des problèmes majeurs liés à la qualité de la bande est la présence possible de porosités dans le coeur de la bande. Lorsque ces porosités se retrouvent sur les produits à l'issue des transformations ultérieures subies par la bande (telles que des décapages, des recuits, des laminages à froid et d'autres opérations de transformation), elles limitent le champ d'application des produits en raison de l'altération des propriétés mécaniques qu'elles procurent.In this casting process which is being industrialized under the name of "Casting between cylinders", one of the major problems related to the quality of the strip is the possible presence of porosities in the core of the strip. When these porosities found on the products at the end of the subsequent transformations undergone by the strip (such as pickling, annealing, cold rolling and other operations of processing), they limit the scope of the products due to spoilage mechanical properties they provide.
Les causes de l'apparition de ces porosités au coeur des bandes coulées entre cylindres peuvent être similaires à celles qui provoquent (à une échelle dimensionnelle supérieure) les retassures dans les lingots et les porosités centrales dans les produits de coulée continue classique, à savoir la fermeture par du métal solide de poches renfermant du métal encore liquide lorsque la solidification du produit (qui, normalement, est substantiellement achevée lorsque la bande quitte les parois de la lingotière, c'est à dire que le coeur de la bande ne se trouve plus totalement à l'état liquide) ne s'effectue pas de manière totalement régulière. Le refroidissement et la solidification du métal liquide que renferment ces poches s'accompagnent d'une contraction de ce métal, qui fait apparaítre un espace vide. Celui-ci ne peut être comblé avant la fin de la solidification, car cette poche refermée n'est plus alimentée par du nouveau métal liquide. Ces porosités doivent être distinguées des défauts sphériques dits « soufflures » qui sont dus à un dégagement de gaz dissous et se produisent le plus souvent à proximité de la surface des produits.The causes of the appearance of these porosities at the heart of the bands cast between cylinders can be similar to those that cause (on a dimensional scale upper) the shrinkage in the ingots and the central porosities in the products of classic continuous casting, namely the closure of pockets containing solid metal still liquid metal when the solidification of the product (which normally is substantially completed when the strip leaves the walls of the ingot mold, i.e. the core of the strip is no longer completely in the liquid state) is not carried out completely regularly. The cooling and solidification of the liquid metal that enclose these pockets are accompanied by a contraction of this metal, which causes a empty space. This can not be filled before the end of solidification, because this pocket closed is no longer fed by new liquid metal. These porosities must be distinguished from spherical faults called "blowing" which are due to a release of gas dissolved and most often occur near the surface of products.
Le document EP 0 396 862 propose un procédé visant à supprimer les porosités centrales, et également d'autres défauts internes et superficiels, lors de la coulée de bandes d'acier entre deux cylindres. Selon ce procédé, les cylindres de coulée comportent sur leurs surfaces des rainures circonférentielles précisément dimensionnées, et disposées de manière décalée sur les deux cylindres. On vise ainsi à éviter des décollements des peaux métalliques solidifiées sur les surfaces des cylindres, qui entraíneraient des irrégularités dans la solidification de la bande. Il apparaít cependant que la seule prévention de ces décollements est insuffisante pour éviter totalement l'apparition des porosités centrales.Document EP 0 396 862 proposes a process aimed at eliminating the porosities central, and also other internal and superficial defects, when casting strips of steel between two cylinders. According to this process, the casting rolls have on their surfaces of the circumferential grooves precisely dimensioned, and arranged in offset on the two cylinders. We thus aim to avoid peeling of the skins solidified metal on the surfaces of the cylinders, which would cause irregularities in solidifying the strip. However, it appears that the only prevention of these detachments is insufficient to completely avoid the appearance of central porosities.
Le document JP 8252653 propose un procédé selon lequel on pratique en ligne
avec la coulée un laminage à chaud de la bande dans des conditions respectant l'inégalité
suivante :
- r : taux de réduction du laminage à chaud ;
- T : température de laminage à chaud en °C ;
- t0: diamètre de la porosité dans le sens de l'épaisseur de la bande ;
- w0 :diamètre de la porosité dans le sens de la largeur de la bande.
- r: reduction rate of hot rolling;
- T: hot rolling temperature in ° C;
- t 0 : diameter of the porosity in the direction of the thickness of the strip;
- w 0 : diameter of the porosity in the direction of the width of the strip.
Il faut donc, selon ce procédé, que le laminage à chaud s'effectue avec un taux de réduction suffisant pour que les porosités soient refermées pendant ce laminage, et ce taux minimal dépend de la température de laminage (c'est à dire la température à laquelle se trouve la bande à son entrée dans l'emprise des cylindres) et de la forme et de l'orientation des porosités. Cependant, on a constaté que ces conditions de laminage sont encore insuffisantes pour obtenir assurément une fermeture de toutes les porosités, et surtout qu'elles n'évitent pas toujours que les porosités refermées ne s'ouvrent à nouveau lors de la transformation de la bande ou de la mise en oeuvre des produits qui en sont issus, ce qui provoque leur rupture.According to this process, it is therefore necessary that the hot rolling takes place with a rate of sufficient reduction for the porosities to be closed during this rolling, and this rate minimum depends on the rolling temperature (i.e. the temperature at which finds the strip as it enters the grip of the cylinders) and the shape and orientation porosities. However, it has been found that these rolling conditions are still insufficient to ensure that all the pores are closed, and above all that they do not always prevent the closed porosities from reopening during the transformation of the strip or the implementation of the products which result therefrom, which causes their rupture.
Le but de l'invention est de proposer un procédé garantissant une fermeture définitive des porosités centrales apparues dans le coeur de la bande après sa solidification complète.The object of the invention is to propose a method guaranteeing closure final of the central porosities appeared in the core of the strip after its solidification complete.
A cet effet, l'invention a pour objet un procédé de fabrication d'une bande mince en acier inoxydable par solidification directe de l'acier liquide sous forme d'une bande d'épaisseur inférieure ou égale à 8 mm dans une installation de coulée comportant deux parois refroidies en mouvement et par laminage à chaud de ladite bande dont la solidification est substantiellement achevée lorsqu'elle quitte lesdites parois, caractérisé en ce que le laminage à chaud est effectué sur un laminoir dont les cylindres de travail ont un diamètre compris entre 400 et 900 mm, en ce que la température de la bande à sa sortie du laminoir est comprise entre 800 et 1100°C, et en ce que le taux de réduction de l'épaisseur de la bande lors du laminage à chaud est compris entre 15 et 50%.To this end, the subject of the invention is a method for manufacturing a thin strip. stainless steel by direct solidification of the liquid steel in the form of a strip of thickness less than or equal to 8 mm in a casting installation comprising two cooled walls in movement and by hot rolling of said strip, the solidification is substantially completed when it leaves said walls, characterized in what hot rolling is done on a rolling mill whose working rolls have a diameter between 400 and 900 mm, in that the temperature of the strip on leaving the rolling mill is between 800 and 1100 ° C, and in that the rate of thickness reduction of the strip during hot rolling is between 15 and 50%.
Préférentiellement, le laminage à chaud est effectué en ligne avec la coulée de la bande. L'installation de coulée peut être du type « coulée entre cylindres ».Preferably, the hot rolling is carried out in line with the casting of the bandaged. The casting installation can be of the “casting between cylinders” type.
Comme on l'aura compris, le but de l'invention est atteint par la combinaison d'exigences portant sur le diamètre des cylindres de travail du laminoir à chaud, la température de la bande à sa sortie des cylindres et le taux de réduction de l'épaisseur de la bande lors du laminage à chaud.As will be understood, the object of the invention is achieved by the combination requirements relating to the diameter of the working rolls of the hot rolling mill, the temperature of the strip at its exit from the cylinders and the rate of reduction of the thickness of the strip during hot rolling.
L'invention s'applique à la coulée d'aciers inoxydables de toutes classes, qui ont classiquement des teneurs en carbone inférieures ou égales à 1%, des teneurs en silicium inférieures ou égales à 1%, des teneurs en manganèse inférieures ou égales à 15%, des teneurs en chrome comprises entre 10 et 30%, des teneurs en cuivre inférieures ou égales à 5% et des teneurs en azote inférieures ou égales à 0,5% (ces teneurs sont exprimées en pourcentages pondéraux). Ces aciers peuvent également contenir des quantités importantes de nickel (jusqu'à 40%) ou de molybdène (jusqu'à 8%). Par ailleurs, comme c'est habituellement le cas, d'autres éléments sont présents dans le métal, soit au titre d'impuretés, soit au titre d'éléments d'alliage, en particulier du soufre, du phosphore, du titane, du niobium, du zirconium. Leur total ne doit pas dépasser 2% en poids.The invention applies to the casting of stainless steels of all classes, which have conventionally carbon contents less than or equal to 1%, silicon contents less than or equal to 1%, manganese contents less than or equal to 15%, chromium contents between 10 and 30%, copper contents less than or equal to 5% and nitrogen contents less than or equal to 0.5% (these contents are expressed in weight percentages). These steels can also contain significant quantities nickel (up to 40%) or molybdenum (up to 8%). By the way, as it is usually the case, other elements are present in the metal, impurities, either as alloying elements, in particular sulfur, phosphorus, titanium, niobium, zirconium. Their total must not exceed 2% by weight.
Comme on l'a dit, une bande mince d'acier inoxydable coulée entre cylindres est fortement susceptible de développer des porosités dans son coeur, lors de sa solidification, lorsqu'une poche liquide est refermée par du métal solide. Ce phénomène se produit en fin de solidification de la zone pâteuse, appelée aussi « zone équiaxe », située entre les deux peaux solidifiées au contact des cylindres, appelées aussi « zones colonnaires ». La zone équiaxe est très difficile à maítriser, et son épaisseur peut varier en fonction de la vitesse de solidification des zones colonnaires. Ainsi, la zone équiaxe peut se refermer localement de manière anticipée, aux niveaux où la croissance des zones colonnaires a été plus rapide que la normale. En aval du point de fermeture de la zone équiaxe, les poches liquides ne peuvent plus être correctement réalimentées en métal liquide, et des porosités se forment par contraction du métal lors de la solidification de ces poches liquides. Ce cas reste néanmoins assez rare, et en fait, généralement, l'isolement d'une poche liquide se produit par le regroupement dans le liquide de cristaux équiaxes qui viennent former un bouchon obstruant la zone équiaxe. Les porosités qui se forment dans la zone équiaxe sont constituées par des ensembles de canaux et de cavités exempts de gaz, dont la dimension maximale selon l'épaisseur de la tôle correspond à l'épaisseur de la zone équiaxe (soit 100 à 400 µm), et qui peuvent atteindre une longueur de 1 à 2 mm dans les autres directions. Comme on l'a dit, il ne s'agit pas d'une soufflure sphérique qui aurait pour origine un dégagement de gaz, ou d'un défaut interne débouchant à la surface de la bande.As mentioned, a thin strip of stainless steel poured between cylinders is highly likely to develop porosities in its heart, during its solidification, when a liquid pocket is closed with solid metal. This phenomenon occurs at the end of solidification of the pasty zone, also called "equiaxial zone", located between the two skins solidified in contact with the cylinders, also called "columnar areas". The area equiaxial is very difficult to control, and its thickness can vary depending on the speed of solidification of columnar areas. Thus, the equiaxial zone can close locally from anticipated, at levels where the growth of columnar areas has been faster than the normal. Downstream of the closing point of the equiaxial zone, the liquid bags do not can no longer be properly replenished with liquid metal, and porosities form by contraction of the metal during the solidification of these liquid pockets. This case remains nevertheless quite rare, and in fact, generally, the isolation of a liquid pocket occurs by the grouping in the liquid of equiaxial crystals which come to form a plug obstructing the equiaxial zone. The porosities which form in the equiaxial zone are consisting of sets of gas-free channels and cavities, the dimension of which maximum according to the thickness of the sheet corresponds to the thickness of the equiaxial zone (i.e. 100 at 400 µm), and which can reach a length of 1 to 2 mm in the other directions. As we said, it is not a spherical blow which would originate from a evolution of gas, or an internal fault opening on the surface of the strip.
L'idée à la base de l'invention est de créer, lors du laminage à chaud de la bande solidifiée, des conditions telles qu'elles conduisent non seulement à une fermeture des porosités centrales comme il est déjà connu, mais également à un véritable soudage des parois opposées des porosités, que le laminage a permis de rapprocher. De cette façon, on s'assure que les porosités ne risqueront pas de s'ouvrir lors des mises en forme ultérieures de la bande ou lors de l'utilisation des produits ainsi réalisés. Lors du laminage à chaud de la bande, deux étapes se succèdent. Tout d'abord, les parois internes du défaut se rapprochent progressivement au fur et à mesure que l'épaisseur de la bande se réduit, jusqu'à leur mise en contact. Puis, une fois ce contact réalisé, un soudage des parois se réalise par diffusion des éléments constitutifs de l'acier au travers de l'interface. Mais un soudage efficace des parois doit déjà avoir été obtenu dès avant la sortie de la bande de l'emprise des cylindres du laminoir, car sinon le relâchement de la compression de la bande qui se produit en sortie des cylindres conduit à un décollement partiel des parois.The idea behind the invention is to create, during the hot rolling of the strip solidified, conditions such that they lead not only to a closure of central porosities as it is already known, but also a real welding of opposite walls of the porosities, which the rolling made it possible to bring together. In this way, we ensures that the porosities are not likely to open during subsequent shaping of the strip or when using the products thus produced. When hot rolling the strip, two stages follow one another. First, the internal walls of the defect are gradually approach as the thickness of the strip decreases, until brought into contact. Then, once this contact has been made, the walls are welded produced by diffusion of the constituent elements of steel through the interface. But one efficient welding of the walls must already have been obtained before the exit of the strip the grip of the rolls of the rolling mill, because otherwise the relaxation of the compression of the strip which occurs at the outlet of the cylinders leads to a partial detachment of the walls.
L'efficacité du soudage dépend essentiellement de deux paramètres : la durée de la mise en contact forcé des parois dans le laminoir et la température à laquelle s'effectue cette mise en contact. Ce contact forcé doit donc avoir lieu dès que possible après l'entrée de la bande dans le laminoir, et sa durée dépend principalement, pour une vitesse de laminage donnée (qui est, dans le cas d'un laminage en ligne, en grande partie conditionnée par l'épaisseur de la bande avant son laminage), du diamètre des cylindres de travail du laminoir et du taux de réduction de son épaisseur qu'ils imposent à la bande. Plus le diamètre des cylindres et le taux de réduction sont élevés, et plus la mise en contact forcé des parois des porosités est rapide et prolongée. On ne peut toutefois pas se contenter d'affirmer qu'il suffit, pour résoudre le problème posé de manière satisfaisante, de laminer la bande avec un taux de réduction et un diamètre de cylindres aussi élevés que possible. En effet, un taux de réduction trop élevé, qui irait au-delà des capacités de déformation à chaud de la bande, conduit à l'apparition de fissures superficielles sur la bande appelées « criques », qui sont absolument à éviter. D'autre part, la température à laquelle s'effectue la mise en contact forcé des parois des porosités dépend non seulement de la température d'entrée de la bande dans le laminoir, mais aussi de la durée du contact entre la bande et les cylindres, car ce contact provoque un refroidissement de la bande. Si, pour une température d'entrée de la bande donnée, les cylindres ont un diamètre très élevé, le refroidissement de la bande qu'ils provoquent risque de conduire celle-ci à une température insuffisante pour que le soudage des parois des porosités puisse être complet. A cet effet, la valeur de la température de la bande à sa sortie des cylindres fournit une bonne indication de la réelle possibilité qu'ont eu les parois des porosités de se souder les unes aux autres dans l'emprise des cylindres.The efficiency of welding essentially depends on two parameters: the duration of the forced contact of the walls in the rolling mill and the temperature at which it takes place this contact. This forced contact must therefore take place as soon as possible after entry of the strip in the rolling mill, and its duration depends mainly, for a speed of given rolling (which is, in the case of in-line rolling, largely conditioned by the thickness of the strip before it is rolled), the diameter of the working rolls of the rolling mill and the reduction rate of its thickness which they impose on the strip. The longer the cylinder diameter and reduction rate, the higher the forced contact of the walls of the porosities is rapid and prolonged. We cannot, however, be satisfied to assert that it suffices, in order to solve the problem posed satisfactorily, to laminate the strip with a reduction ratio and a cylinder diameter as high as possible. Indeed, a reduction rate too high, which would go beyond the deformation capacities to hot of the strip, leads to the appearance of surface cracks on the strip called "Coves", which are absolutely to be avoided. On the other hand, the temperature at which takes place the forced contacting of the walls of the poros depends not only on the temperature of entry of the strip into the rolling mill, but also of the duration of contact between the strip and the cylinders, because this contact causes the strip to cool. If, for a temperature entry of the given strip, the cylinders have a very large diameter, the cooling of the strip which they cause risks leading it to a temperature insufficient for that the welding of the walls of the porosities can be complete. For this purpose, the value of the temperature of the strip as it leaves the cylinders provides a good indication of the actual possibility that the walls of the porosities had to weld to each other in the grip of the cylinders.
La température de la bande à la sortie des cylindres doit donc être suffisante pour permettre le soudage des porosités, mais elle ne doit pas être non plus trop élevée, afin d'éviter une charge thermique excessive sur les cylindres. Celle-ci conduirait à une dégradation de leur surface aboutissant à une détérioration de l'aspect de surface de la bande sous la forme d'une rugosité excessive. L'objectif de l'invention ne peut donc être atteint sans l'obtention d'effets secondaires gênants pour la qualité générale de la bande que si on combine le diamètre des cylindres, le taux de réduction et la température de la bande en sortie du laminoir de manière adéquate.The temperature of the strip at the outlet of the cylinders must therefore be sufficient to allow the welding of porosities, but it must not be too high either, so avoid excessive thermal load on the cylinders. This would lead to a degradation of their surface resulting in a deterioration of the surface appearance of the strip in the form of excessive roughness. The objective of the invention cannot therefore be achieved without getting annoying side effects for the overall quality of the tape that if we combine the diameter of the cylinders, the reduction rate and the temperature of the strip leaving the rolling mill adequately.
Pour déterminer comment ces paramètres doivent être combinés, on a effectué des séries d'essais, au cours desquels, pour un type d'acier inoxydable donné, on a fait varier le diamètre des cylindres de travail du laminoir, le taux de réduction de l'épaisseur de la bande et la température de la bande en sortie du laminoir. Le laminoir était disposé en ligne avec l'installation de coulée. Chaque essai a fait l'objet d'une caractérisation permettant de déterminer si le soudage des porosités a été efficace ou non. Cette caractérisation a consisté à casser une éprouvette de traction et à examiner le faciès de rupture. Si le faciès présente des porosités qui se sont ouvertes au cours de l'essai de traction, on déduit que le soudage n'a pas été satisfaisant. Si le faciès ne présente aucune porosité apparente, le soudage est jugé avoir été satisfaisant.To determine how these parameters should be combined, we carried out series of tests, during which, for a given type of stainless steel, the diameter of the working rolls of the rolling mill, the rate of reduction of the thickness of the strip and the temperature of the strip leaving the rolling mill. The rolling mill was arranged in line with the casting facility. Each test was subject to a characterization allowing determine whether the porosity welding has been effective or not. This characterization consisted to break a tensile test piece and to examine the facies of rupture. If the facies present porosities which opened during the tensile test, it is deduced that the welding was not satisfactory. If the facies have no apparent porosity, the welding is found to have been satisfactory.
Le tableau 1 regroupe les compositions des aciers sur lesquels ont été effectués les essais dont les résultats sont donnés dans le tableau 2. Les teneurs des différents éléments sont données en pourcentages pondéraux. Le tableau 1 donne également les épaisseurs en sortie des cylindres de coulée des bandes sur lesquelles les essais ont été effectués, ainsi que les vitesses de coulée correspondantes, mesurées entre les cylindres de coulée et le laminoir à chaud. Table 1 groups together the compositions of the steels on which the tests were carried out, the results of which are given in Table 2. The contents of the various elements are given in percentages by weight. Table 1 also gives the thicknesses at the outlet of the casting rolls of the strips on which the tests were carried out, as well as the corresponding casting speeds, measured between the casting rolls and the hot rolling mill.
Les compositions des coulées de types A et A' correspondent à celles d'aciers inoxydables austénitiques classiques de type AISI 304. Les coulées de type B correspondent à des aciers inoxydables ferritiques de type AISI 430. Les coulées de type C correspondent à des aciers inoxydables ferritiques de type AISI 409 stabilisé au titane.The compositions of types A and A 'flows correspond to those of steels classic austenitic stainless steels type AISI 304. Type B castings correspond to AISI 430 type ferritic stainless steels. Type C castings correspond to AISI 409 ferritic stainless steels stabilized with titanium.
Le tableau 2 expose les résultats d'essais effectués sur les bandes issues de ces
coulées, avec les conditions d'essai correspondantes.
Il ressort de ces essais qu'un soudage efficace des porosités est obtenu sans apparition de criques et sans rugosité excessive à la surface de la bande lorsque les trois conditions suivantes sont réunies :
- un diamètre des cylindres de travail du laminoir compris entre 400 et 900 mm ;
- un taux de réduction de l'épaisseur de la bande lors du laminage compris entre 15 et 50%;
- une température de la bande en sortie du laminoir d'au moins 800°C et d'au plus 1100°C.
- a diameter of the working rolls of the rolling mill between 400 and 900 mm;
- a reduction rate of the strip thickness during rolling between 15 and 50%;
- a temperature of the strip leaving the rolling mill of at least 800 ° C. and at most 1100 ° C.
En revanche, on n'a pas noté d'influence, dans les conditions d'essais, de la combinaison épaisseur de la bande-vitesse de coulée : les résultats des coulées de type A' sont identiques à ceux des coulées de type A, pour des paramètres de coulée par ailleurs identiques.On the other hand, no influence was noted, under the test conditions, of the Strip thickness-casting speed combination: results of type A 'castings are identical to those of type A castings, for other casting parameters identical.
Ces essais, comme on l'a dit, ont été effectués avec un laminoir à chaud disposé en ligne avec l'installation de coulée et précédant l'installation de bobinage de la bande. Dans l'esprit de l'invention, cette caractéristique n'est pas indispensable, et le laminage à chaud peut être effectué sur une installation séparée de l'installation de coulée et de bobinage, donc après un débobinage et un réchauffage de la bande brute de coulée. Cependant, un laminage en ligne est conseillé pour diverses raisons. Tout d'abord, cette solution présente des avantages économiques liés au caractère continu des opérations. En premier lieu, le processus de fabrication de la bande s'en trouve raccourci. De plus, on fait l'économie d'une bobineuse, et aussi d'une installation de réchauffage de relativement forte puissance puisque la bande coulée peut être suffisamment chaude pour obtenir les températures de laminage adéquates, éventuellement à l'aide d'un capot arrêtant le rayonnement de la bande entre sa sortie des cylindres de coulée et son entrée dans le laminoir. Si un réchauffage de la bande s'avère cependant nécessaire, il peut être effectué à l'aide d'un four à induction de puissance réduite, suffisante pour élever la température de la bande en défilement de quelques centaines de degrés. D'autre part un laminage en ligne, en supprimant la nécessité d'un bobinage de la bande brute de coulée, supprime du même coup les risques de détérioration de la bande lors de ce bobinage qui aurait lieu sur une bande relativement épaisse présentant une structure non recristallisée. Enfin, la suppression du réchauffage de la bande à partir de la température ambiante jusqu'à la température de laminage à chaud supprime les réoxydations de la surface de la bande qui sont habituelles lors de cette opération. Ces réoxydations formeraient de la calamine, qui risquerait de s'incruster à la fois dans la bande et dans les cylindres du laminoir et de conduire ainsi à une dégradation de l'aspect de surface du produit après décapage.These tests, as we said, were carried out with a hot rolling mill arranged in line with the casting installation and preceding the tape winding installation. In the spirit of the invention, this characteristic is not essential, and rolling to hot can be carried out on a separate installation from the casting installation and winding, so after unwinding and reheating the raw casting strip. However, inline lamination is advised for a variety of reasons. First of all, this solution has economic advantages linked to the continuous nature of operations. In first, the tape manufacturing process is shortened. In addition, we do the economy of a winder, and also of a reheating installation of relatively high power since the casting strip can be hot enough to obtain the adequate rolling temperatures, possibly using a hood to stop the radiation of the strip between its exit from the casting cylinders and its entry into the rolling mill. If a reheating of the strip is however necessary, it can be carried out at using an induction furnace of reduced power, sufficient to raise the temperature of the strip running a few hundred degrees. On the other hand, in-line rolling, in eliminating the need for a winding of the raw casting strip, also eliminates suddenly the risks of deterioration of the strip during this winding which would take place on a relatively thick strip with an unrecrystallized structure. Finally, the removal reheating the strip from room temperature to the temperature of hot rolling removes the usual reoxidation of the strip surface during this operation. These re-oxidations would form scale, which could cause become embedded both in the strip and in the rolls of the rolling mill and thus lead to degradation of the surface appearance of the product after pickling.
L'invention s'applique non seulement aux installations de coulée entre cylindres, mais à toute autre type d'installation de coulée de bandes minces d'acier inoxydable entre deux surfaces refroidies en mouvement, telles que des bandes en défilement.The invention applies not only to installations for casting between rolls, but to any other type of casting installation of thin strips of stainless steel between two cooled surfaces in motion, such as moving bands.
Claims (3)
- Method of manufacturing a thin stainless steel strip by direct solidification of liquid steel in the form of a strip of a thickness less than or equal to 8mm in a casting apparatus comprising two cooled walls in motion, and by hot rolling of the said strip the solidification of which is substantially achieved when it leaves the said walls, characterised in that hot rolling is carried out on a rolling mill the working cylinders of which have a diameter of between 400 and 900 mm, in that the temperature of the strip when it comes out of the rolling mill is between 800 and 1100°C, and in that the rate of reduction in the thickness of the strip when it is hot rolled is between 15 and 50%.
- Method according to claim 1, characterised in that hot rolling is carried out on apparatus arranged in line with the casting apparatus.
- Method according to claim 1 or 2, characterised in that the cooled walls of the casting apparatus are formed by the surfaces of the two cylinders in rotation on horizontal axes.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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FR9811777 | 1998-09-21 | ||
FR9811777A FR2783443B1 (en) | 1998-09-21 | 1998-09-21 | PROCESS FOR THE MANUFACTURE OF A STAINLESS STEEL THIN STRIP |
Publications (2)
Publication Number | Publication Date |
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EP0988901A1 EP0988901A1 (en) | 2000-03-29 |
EP0988901B1 true EP0988901B1 (en) | 2003-11-12 |
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Application Number | Title | Priority Date | Filing Date |
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EP99402235A Revoked EP0988901B1 (en) | 1998-09-21 | 1999-09-10 | Manufacturing method for stainless steel thin strip |
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EP (1) | EP0988901B1 (en) |
JP (1) | JP2000094006A (en) |
KR (1) | KR100573750B1 (en) |
CN (1) | CN100358645C (en) |
AT (1) | ATE253992T1 (en) |
AU (1) | AU4877899A (en) |
BR (1) | BR9904278A (en) |
CA (1) | CA2281991A1 (en) |
DE (1) | DE69912710T2 (en) |
FR (1) | FR2783443B1 (en) |
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TR (1) | TR199902306A3 (en) |
TW (1) | TW483781B (en) |
UA (1) | UA63941C2 (en) |
ZA (1) | ZA995983B (en) |
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DE10046181C2 (en) * | 2000-09-19 | 2002-08-01 | Krupp Thyssen Nirosta Gmbh | Process for producing a steel strip or sheet consisting predominantly of Mn austenite |
ITRM20070150A1 (en) * | 2007-03-21 | 2008-09-22 | Danieli Off Mecc | PROCESS AND PLANT FOR THE PRODUCTION OF METAL TAPES |
CN110404967A (en) * | 2019-07-16 | 2019-11-05 | 山西太钢不锈钢精密带钢有限公司 | The manufacturing method of the ultra-thin superhard stainless steel belt of ultra-wide and its steel band of manufacture |
CN114247760B (en) * | 2020-09-23 | 2024-02-13 | 宝山钢铁股份有限公司 | Comprehensive diagnosis method for cold rolling broken belt of brittle material |
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JPH02224853A (en) | 1989-02-27 | 1990-09-06 | Kawasaki Steel Corp | Cooling roll for producing twin roll type rapidly cooling strip |
JP2798694B2 (en) | 1989-03-17 | 1998-09-17 | 新日本製鐵株式会社 | Manufacturing method of thin cast slab |
JPH03124352A (en) * | 1989-10-09 | 1991-05-27 | Kobe Steel Ltd | Production of continuously cast slab having excellent internal quality |
JP2690191B2 (en) * | 1990-11-30 | 1997-12-10 | 新日本製鐵株式会社 | Method for producing high δ-Fe-based austenitic stainless steel strip |
JP2995520B2 (en) * | 1992-10-20 | 1999-12-27 | 新日本製鐵株式会社 | How to improve the quality of continuous cast slabs |
JPH07251244A (en) * | 1994-03-16 | 1995-10-03 | Nippon Steel Corp | Method for preventing porosity of cast slab in twin roll type continuous casting method |
WO1996001710A1 (en) * | 1994-07-08 | 1996-01-25 | Ipsco Inc. | Method of casting and rolling steel using twin-roll caster |
JPH08215797A (en) * | 1995-02-16 | 1996-08-27 | Nippon Steel Corp | Production of austenitic stainless steel thin cast slab excellent in surface characteristic and formability |
JP2982646B2 (en) * | 1995-03-16 | 1999-11-29 | 住友金属工業株式会社 | Continuous production of thin steel sheets |
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1998
- 1998-09-21 FR FR9811777A patent/FR2783443B1/en not_active Expired - Fee Related
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1999
- 1999-09-09 CA CA002281991A patent/CA2281991A1/en not_active Abandoned
- 1999-09-10 DE DE69912710T patent/DE69912710T2/en not_active Revoked
- 1999-09-10 EP EP99402235A patent/EP0988901B1/en not_active Revoked
- 1999-09-10 AT AT99402235T patent/ATE253992T1/en not_active IP Right Cessation
- 1999-09-10 SK SK1239-99A patent/SK123999A3/en unknown
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- 1999-09-20 CN CNB991220633A patent/CN100358645C/en not_active Expired - Fee Related
- 1999-09-20 TR TR1999/02306A patent/TR199902306A3/en unknown
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- 1999-09-21 JP JP11266489A patent/JP2000094006A/en active Pending
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PL335499A1 (en) | 2000-03-27 |
RU2203749C2 (en) | 2003-05-10 |
DE69912710T2 (en) | 2004-09-23 |
TW483781B (en) | 2002-04-21 |
CN100358645C (en) | 2008-01-02 |
UA63941C2 (en) | 2004-02-16 |
FR2783443A1 (en) | 2000-03-24 |
ATE253992T1 (en) | 2003-11-15 |
DE69912710D1 (en) | 2003-12-18 |
BR9904278A (en) | 2000-09-26 |
JP2000094006A (en) | 2000-04-04 |
ID25947A (en) | 2000-11-16 |
CN1249216A (en) | 2000-04-05 |
FR2783443B1 (en) | 2000-10-27 |
EP0988901A1 (en) | 2000-03-29 |
TR199902306A2 (en) | 2000-04-21 |
AU4877899A (en) | 2000-03-23 |
TR199902306A3 (en) | 2000-04-21 |
ZA995983B (en) | 2001-03-19 |
KR100573750B1 (en) | 2006-04-24 |
SK123999A3 (en) | 2000-07-11 |
KR20000023300A (en) | 2000-04-25 |
CA2281991A1 (en) | 2000-03-21 |
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