EP0524162B1 - Procédé de fabrication d'une bande mince en acier doux - Google Patents
Procédé de fabrication d'une bande mince en acier doux Download PDFInfo
- Publication number
- EP0524162B1 EP0524162B1 EP92870104A EP92870104A EP0524162B1 EP 0524162 B1 EP0524162 B1 EP 0524162B1 EP 92870104 A EP92870104 A EP 92870104A EP 92870104 A EP92870104 A EP 92870104A EP 0524162 B1 EP0524162 B1 EP 0524162B1
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- EP
- European Patent Office
- Prior art keywords
- strip
- less
- cold
- rolling
- temperature
- 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
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
- C21D8/0421—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the working steps
- C21D8/0426—Hot rolling
-
- 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
- B21B1/22—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 plates, strips, bands or sheets of indefinite length
- B21B1/24—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 plates, strips, bands or sheets of indefinite length in a continuous or semi-continuous process
- B21B1/26—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 plates, strips, bands or sheets of indefinite length in a continuous or semi-continuous process by hot-rolling, e.g. Steckel hot mill
-
- 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
- C21D8/0231—Warm rolling
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B2201/00—Special rolling modes
- B21B2201/02—Austenitic rolling
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B2201/00—Special rolling modes
- B21B2201/04—Ferritic rolling
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B27/00—Rolls, roll alloys or roll fabrication; Lubricating, cooling or heating rolls while in use
- B21B27/06—Lubricating, cooling or heating rolls
- B21B27/10—Lubricating, cooling or heating rolls externally
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
- B21B45/004—Heating the product
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
- B21B45/02—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for lubricating, cooling, or cleaning
- B21B45/0239—Lubricating
- B21B45/0242—Lubricants
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
- B21B45/02—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for lubricating, cooling, or cleaning
- B21B45/0239—Lubricating
- B21B45/0245—Lubricating devices
- B21B45/0263—Lubricating devices using solid lubricants
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- 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
- C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
- C21D8/0421—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the working steps
- C21D8/0431—Warm rolling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
- C21D8/0447—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the heat treatment
- C21D8/0463—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the heat treatment following hot rolling
Definitions
- the present invention relates to a method of manufacturing a strip thin mild steel, i.e. with a lower carbon content 0.2%, and preferably less than 0.1%.
- the thin strip has a thickness less than or equal to 2 mm.
- a thin strip, coated or not is used in particular in automobile bodywork and in household appliances.
- the strip of the invention can be used for example for the manufacture of tinplate.
- a hot rolled, ductile and formable strip we use usually a continuously cast mild steel slab, the thickness of which is generally between 150 mm and 300 mm. After it solidifies, the slab is loaded into a reheating oven where it is homogenized at a high temperature, generally above 1000 ° C, before being hot rolled. Before reheating the homogenization, the slab may have been cooled to a relatively low temperature, possibly go to room temperature; we then put in the oven says cold. The solidified slab may also have been cooled only up to an intermediate temperature, for example between 600 ° C and 900 ° C; in this case, we practice the so-called hot charging in the oven reheating.
- the slab may have only been cooled partial, up to a temperature which remains above 1000 ° C, and which is preferably between 1000 ° C and 1200 ° C; in that case, the slab is ready to be laminated directly, without going through an oven reheating.
- the slab is rolled at high temperature in a coarse rolling mill, in order to produce a blank having a thickness generally between 20 mm and 40 mm.
- This blank is then rolled in a hot finishing train until the desired final thickness, most often between 1.5 mm and 4 mm.
- the rolled strip On leaving the hot finishing train, the rolled strip generally has a temperature above 850 ° C, in the case of mild steels.
- the tape is finally cooled on the finishing train output table, then it is wound to a temperature generally equal to or higher than 550 ° C.
- This conventional hot rolling practice makes it possible to manufacture a strip hot, ductile and formable, perfectly recrystallized, which can be used directly after pickling or which can be subsequently cold rolled and subjected to recrystallization annealing to produce a thin strip when cold.
- a second cold rolling step may then be necessary to give the thin strip the required mechanical characteristics.
- This manufacturing cycle cold is frequently called "double cold reduction treatment" by reference the two cold rolling operations.
- EP-A-0 194 118 discloses a method for manufacturing a thin strip of formable low carbon steel having high resistance to ripple. This process consists of rolling the low carbon steel with a deformation rate which is not less than 300 ° -1 in a temperature range of 800 ° C-300 ° C in at least one pass and then recrystallizing the laminated strip. No cold rolling is planned.
- the thin slab is homogenized at a temperature below 1100 ° C while remaining in the austenitic domain.
- the slab is then hot rolled, in austenite, in a strip having a thickness of between 2 and 5 mm. After cooling to a temperature such that at least 75% of its structure is transformed into ferrite, but higher than 300 ° C, the strip is laminated with a thickness reduction of at least 25% and a rolling speed lower than 1000 m / min.
- the resistance level results from the whole manufacturing process, and in particular the reduction rate of the second operation of cold rolling; this generally does not exceed 50%. Ductility also depends on the reduction rate during the last cold rolling, as well as the sensitivity to aging of the final product.
- a first method consists in limiting the heating temperature of the slabs at a level such that the dissolution of the nitride AlN does not occur not.
- the disadvantage of this method is that it no longer guarantees hot rolling entirely in the austenitic area, which inevitably leads to heterogeneous structures and irregularities in the dimensions of the hot strips.
- the winding temperature of the hot strips can be increased above 700 ° C, so as to precipitate in the form of the nitride AlN all the nitrogen previously dissolved during the initial reheating.
- too high winding temperatures lead to heterogeneities along and across strips as well as forming a oxide layer of excessive thickness.
- winding temperatures close to 700 ° C give rise to the formation of cementite very coarse, which deteriorates the surface condition of very thin products.
- the current procedure therefore results from a compromise considered until present as optimal: the slabs are heated to a sufficient temperature to carry out hot rolling entirely in the austenitic area, and the strips are hot-rolled at a temperature of 550 ° C. at 650 ° C so as to precipitate part of the nitrogen in the form of nitride AlN without coalescence of the cementite beyond of a certain size.
- the present invention provides a method which overcomes the various drawbacks aforementioned and to manufacture a hot rolled strip free from defects and perfectly homogeneous and whose thickness is equal to or less than 2 mm from of a continuously cast slab whose thickness is between 150 and 300 mm.
- the hot strip obtained by the process of the invention has the quality of embossing, which is all the more desirable as the thickness of the strip is reduced and approaches the usual range of thickness for a cold rolled strip.
- the present invention also provides a method of manufacturing a non-aging cold rolled strip, the dimensional tolerances of which are strictly observed and in which the cementite is finely dispersed.
- the position and extent of the ferritic range of a steel depends in particular on its chemical composition, namely in particular its carbon and alloying elements.
- the temperature of engagement of the finish rolling in the Ferrite can therefore vary depending on the steel used.
- the IF symbol designates "Interstitial Free" steels, that is to say which do not contain atoms interstitial.
- the rolling engagement temperature finishing temperature is 800 ° C or less, and is preferably between 750 ° C and 400 ° C.
- ELC and ULC steels are sensitive to the phenomenon of dynamic aging, well known to specialists; It's about a increased resistance to deformation in certain areas of temperature, due in particular to the presence of atoms of C and N in the steel structure. It is important that rolling in the ferritic phase is so as to avoid significant increases in the burden of rolling, due precisely to this dynamic aging. Indeed, these load increases could lead to mechanical overloads undesirable on the rolling mill stands.
- the temperature of engagement of the finish rolling is between either 750 ° C and 550 ° C, and preferably between 700 ° C and 600 ° C, or between 450 ° C and 250 ° C, and preferably between 400 ° C and 300 ° C.
- the purpose of hot rolling finishing in ferritic phase is to produce thin hot strips which have a work hardened structure. Work hardening of these bands should be high, so that the hardness measured on the hot strips is at least equal to half the hardness that we measure on the same strips after cold rolling with reduction rates greater than 50%.
- the strip hot rolled in ferritic phase which has a hardened structure is then recrystallized.
- the strip is recrystallized by annealing continuous performed directly after finishing rolling; this annealing can then operate the reduction of rolling oxides.
- the hot rolled strip is wound and pickled, and then recrystallized either by continuous annealing or by annealing static on reel.
- An additional variant of the invention consists in making a reel the recrystallization of the hot strip which was work hardened during the rolling in ferritic phase.
- High winding temperatures necessary to ensure recrystallization can be obtained by adapting the cooling on the outlet table and taking advantage of the temperature increase that occurs in the last cages of the finishing rolling mill. This rise in temperature, caused by the deformation of the strip, is all the more important as the work hardening in the last stands of the finishing mill is high.
- the work hardening ⁇ carried out during the rolling of the strip in the ferritic phase is preferably greater than 2. It will be recalled that the work hardening ⁇ is defined as the natural logarithm of the ratio between the initial thickness and the final thickness of the product, c is to say
- the rolling speeds in the ferritic phase are the usual rolling speeds; they are therefore compatible with the possibilities of existing finishing trains.
- the winding temperatures are determined as a function of the temperatures at the end of rolling in the ferritic phase.
- the maximum temperatures reached during the direct annealing of the strips hardened are also adapted according to the nature of the steel to ensure the total recrystallization of it.
- the thin hot strips can then be cold rolled with a reduction rate of at least 20%, to produce thin cold strips of reduced thickness, i.e. less than or equal 1.0 mm, and preferably less than or equal to 0.5 mm. These are then recrystallized by continuous annealing or in coil, to produce quality bands embossing. Cold strips of reduced thickness, i.e. less or equal to 0.5 mm, having a stamping quality can be obtained with cold reduction rates of less than 90% and up to 40%.
- the finishing rolling is carried out in the ferritic field up to a thickness from 0.5 mm to 2 mm with a finish rolling finish temperature between 750 ° C and 300 ° C, to form a hot strip, the strip is wound hot at a temperature between 650 ° C and 200 ° C, said strip is subjected hot at least one cold rolling step to the desired final thickness, with a total reduction rate less than or equal to 95%.
- the heating of the slab can here be limited to a temperature such that the nitride AlN is not dissolved.
- the reheating temperature is between (A c3 + 50 ° C) and 1050 ° C. Furthermore, this temperature is sufficient to avoid reheating in the intercritical phase, that is to say austenitic + ferritic, or in the ferritic phase, which would lead to the formation of very coarse cementite on the hot-rolled strip.
- the roughing rolling is carried out in the austenitic field, to form a blank whose thickness varies according to the thickness of the final product to be manufactured.
- the thickness of the blank is between 20 mm and 50 mm.
- the cooling rate conditions, in known manner, the size of the ferritic grain, the size and the dispersion of the islets of cementite or islets of residual austenite. We therefore carry out a accelerated cooling of the blank, in order to obtain a fine cementite and dispersed and therefore a homogeneous ferritic structure.
- the duration of this cooling is advantageously less than 30 seconds.
- This duration depends on the temperature to which the blank has been cooled. and that will be the start temperature of the finish rolling in the field ferritic. Depending on the value of this temperature, a finely dispersed residual ferrite + austenite mixed structure or a ferritic structure containing finely dispersed cementite.
- the strip is cooled while hot to the temperature of winding. This is preferably between 750 ° C and 200 ° C.
- the thin hot strip is then cold rolled, usually in half operations separated by continuous annealing or continuous coil, up to a final thickness of less than 0.50 mm, and preferably less at 0.20 mm.
- the thickness of the strip is reduced to less than 0.5 mm, and preferably to less than 0.35 mm, with a reduction rate of less than 90%.
- the second cold rolling operation gives the strip its thickness and its final properties, with a reduction rate of less than 50% and preferably less than 30%.
- a first series of examples illustrate the improvements in properties hot strips obtained by the process of the invention.
- Example 1 relates to thin hot strips of ULC-Ti steel.
- Table 1 The data relating to the tests carried out as well as the properties obtained after direct annealing at 825 ° C for 60 s are shown in Table 1, the columns of which have the following meaning: 1) No. indicates the sample number; 1, 2, 3 are thin hot strips conventionally obtained; 4, 5, 6 are hot strips laminated in the ferritic phase and recrystallized. 2) e (mm) final thickness of the hot strip. 3) T e (° C) belt inlet temperature in the finishing train. 4) T s (° C) exit temperature of the belt of the finishing train. 5) T b (° C) hot strip winding temperature. 6) LUB strip laminated with lubricated (L) or unlubricated (N) cylinders.
- Example 2 relates to thin ELC steel hot strips. It is illustrated by Table 2, the columns of which have the same objects as in Table 1. In this example, hot strips # 4, 5 and 6 have undergone direct recrystallization annealing at 720 ° C for 60 s.
- the hot strips produced by the process of the invention have a better ability to deformation than conventional bands: marked improvement in anisotropy coefficients, without decisive modification of the limit of elasticity, breaking load and elongation.
- Example 3 illustrated by Table 3, relates to cold bands in ULC-Ti and ELC types of steel, cold rolled from strip hot recrystallized. Conditions for direct recrystallization annealing are the same as for the corresponding steel grades presented respectively in Tables 1 and 2.
- the process of the invention has improved the deformability compared to conventional cold bands: lower yield strength and breaking load, light increased elongation and more favorable anisotropy coefficients.
- a second series of examples illustrate the manufacture of cold strips.
- the results obtained are collated in Table 4.
- this table also includes the results obtained by a prior art method.
- Example 1 to 5 relate to the invention (+); Example 6 refers to a prior process. 2) T R slab reheating temperature. 3) T D end temperature of roughing rolling. 4) T F end rolling finish temperature. 5) T B hot strip winding temperature. 6) e ch : thickness of the hot strip. 7) e fr1 : thickness of the cold strip after the first cold rolling operation. 8) e fr2 : thickness of the cold strip after the second cold rolling operation. 9) R e (NV): elasticity limit of the non-aged cold strip. 10) R r (NV): non-aged cold strip breaking load. 11) A (NV): elongation of the non-aged cold strip.
- the cold strip produced by the process of the invention has been shown to be immune to aging.
- This characteristic due to the limited heating temperature of the slab, results in remarkable stability of mechanical properties, in particular of the elongation and therefore the ductility of the strip. This result is not not reached the previous process.
- the ductility is clearly higher by the process of the invention than by the previous process, which promotes the implementation of the cold strip produced according to the invention.
- Example 4 relates to the specific case of a band which has suffered only one single cold rolling operation from a recrystallized hot strip by continuous direct annealing.
- the cold strip obtained has also very favorable properties, both with regard to strength as ductility and aging. It thus appears that using a very thin hot strip with a structure hardened, the method of the invention allows, for certain ranges of thicknesses to remove a cold rolling operation without harm the properties of the cold strip obtained.
- a steel strip hot rolled by the process of the invention is distinguished by the absence of aging, as well as by a very low yield strength and breaking load in the case where the laminated structure in the ferritic domain completely recrystallizes, that is to say if the rolling temperature (T F ⁇ 700 ° C) and / or if the winding temperature (T B ⁇ 550 ° C) are sufficiently high.
- steel, also not aging is characterized by a ferritic microstructure with elongated grain, partially or completely restored. Whatever the state of the structure of the hot strip, the cementite is finely dispersed there.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Sheet Steel (AREA)
Description
1) | N° | indique le numéro de l'échantillon; 1, 2, 3 sont des bandes à chaud minces obtenues de manière conventionnelle; 4, 5, 6 sont des bandes à chaud laminées en phase ferritique et recristallisées. |
2) | e (mm) | épaisseur finale de la bande à chaud. |
3) | Te (°C) | température d'entrée de la bande dans le train finisseur. |
4) | Ts (°C) | température de sortie de la bande du train finisseur. |
5) | Tb (°C) | température de bobinage de la bande à chaud. |
6) | LUB | bande laminée avec des cylindres lubrifiés (L) ou non lubrifiés (N). |
7) | ES (%) | écrouissage de la structure de la bande laminée à chaud et bobinée, avant le recuit, déterminé à partir de la dureté HV de la bande, par la relation:
|
8) | Re (MNm-2) | limite d'élasticité de la bande à chaud. |
9) | Rr (MNm-2) | charge de rupture de la bande à chaud. |
10) | A (%) | allongement de la bande à chaud. |
11) | r | coefficient d'anisotropie plastique (Lankford). |
12) | Δr | coefficient d'anisotropie planaire (dans le plan de laminage). |
1) | N° | indique le numéro de l'échantillon; 1, 2 et 5 sont des bandes à chaud minces obtenues de manière conventionnelle; |
3, 4, 6, 7 et 8 ont été produites par le procédé de l'invention. | ||
2) | Acier | type d'acier constituant la bande. |
3) | ES (%) | écrouissage de la structure de la bande laminée à chaud, avant le laminage à froid, déterminé à partir de sa dureté suivant la relation donnée au point (7) des Tableaux 1 et 2. |
4) | RF (%) | taux de réduction total du laminage à froid. |
5) | ef (mm) | épaisseur finale de la bande laminée à froid. |
6) | Re (MNm-2) | limite d'élasticité de la bande à froid. |
7) | Rr (MNm-2) | charge de rupture de la bande à froid. |
8) | A (%): | allongement de la bande à froid. |
9) | r | coefficient d'anisotropie plastique (Lankford). |
10) | Δr | coefficient d'anisotropie planaire (dans le plan de laminage). |
11) | LUB | bande laminée avec des cylindres lubrifiés (L) ou non lubrifiés (N). |
1) | N° | numéro de l'exemple. Les exemples 1 à 5 se rapportent à l'invention (+); l'exemple 6 se réfère à un procédé antérieur. |
2) | TR | température de réchauffage de la brame. |
3) | TD | température de fin du laminage de dégrossissage. |
4) | TF | température de fin du laminage de finition. |
5) | TB | température de bobinage de la bande à chaud. |
6) | ech : | épaisseur de la bande à chaud. |
7) | efr1 : | épaisseur de la bande à froid après la première opération de laminage à froid. |
8) | efr2 : | épaisseur de la bande à froid après la seconde opération de laminage à froid. |
9) | Re(NV): | limite d'élasticité de la bande à froid non vieillie. |
10) | Rr(NV): | charge de rupture de la bande à froid non vieillie. |
11) | A (NV): | allongement de la bande à froid non vieillie. |
12) | Re (V): | limite d'élasticité de la bande à froid après vieillissement de 50 jours à 50°C. |
13) | Rr (V): | charge de rupture de la bande à froid après vieillissement de 50 jours à 50°C. |
14) | A (V): | allongement de la bande à froid après vieillissement de 50 jours à 50°C. |
Claims (13)
- Procédé de fabrication d'une bande mince en acier doux d'une épaisseur égale ou inférieure à 2 mm, à partir d'une brame coulée en continu dont l'épaisseur est comprise entre 150 et 300 mm, ledit procédé comportant une étape de laminage de finition à chaud, avec des cylindres lubrifiés, dans lequel :a) on refroidit ladite brame jusqu'à une température suffisante pour assurer la précipitation des éléments en solution, dont au moins le carbone et/ou l'azote;b) on réchauffe ladite brame jusqu'à une température comprise entre (Ac3 + 50°C) et 1050°C;c) on effectue un laminage de dégrossissage de la brame dans le domaine austénitique pour former une ébauche dont l'épaisseur est comprise entre 20 et 50 mm;d) on refroidit ladite ébauche jusqu'à une température à laquelle ledit acier présente une structure ferritique;e) on effectue ledit laminage de finition dans un domaine de température où l'acier présente une structure ferritique, avec une température de fin de laminage égale ou inférieure à 750°C, pour former une bande à chaud d'une épaisseur égale ou inférieure à 2 mm; etf) on soumet ladite bande à chaud à un recuit de recristallisation.
- Procédé suivant la revendication 1, caractérisé en ce que la bande est en acier du type ULC - IF, c'est-à-dire à teneur en carbone inférieure à 0,01 %, sans interstitiels, et en ce que la température d'engagement du laminage de finition est inférieure à 800°C.
- Procédé suivant la revendication 1, caractérisé en ce que la bande est en acier du type ELC, c'est-à-dire à teneur en carbone inférieure à 0,1 %, ou ULC, c'est-à-dire à teneur en carbone inférieure à 0,01 %, et en ce que la température d'engagement du laminage de finition est comprise entre 750°C et 550°C ou entre 450°C et 250°C.
- Procédé suivant l'une ou l'autre des revendications 1 à 3, caractérisé en ce que le taux de réduction appliqué à la bande au cours dudit laminage de finition est égal ou supérieur à 50 %.
- Procédé suivant l'une ou l'autre des revendications 1 à 4, caractérisé en ce que le recuit de recristallisation de la bande à chaud est réalisé en continu, de préférence immédiatement après le laminage de finition.
- Procédé suivant l'une ou l'autre des revendications 1 à 4, caractérisé en ce que le recuit de recristallisation de la bande à chaud est réalisé en bobine.
- Utilisation d'une bande à chaud obtenue par un procédé suivant l'une ou l'autre des revendications 1 à 6, pour la fabrication d'une bande laminée à froid d'une épaisseur inférieure ou égale à 1,0 mm, et de préférence à 0,50 mm, dans laquelle on lamine à froid la bande à chaud avec un taux de réduction à froid compris entre 40 % et 90 %.
- Procédé de fabrication d'une bande ultra-mince en acier doux de type ELC, c'est-à-dire à teneur en carbone inférieure à 0,1 %, laminée à froid, non vieillissante, à partir d'une bande à chaud obtenue par le procédé suivant l'une ou l'autre des revendications 1 à 6, dans lequel on soumet ladite bande à chaud à une opération de laminage à froid, caractérisé en ce que l'on effectue ledit laminage de finition dans le domaine ferritique jusqu'à une épaisseur de 0,5 mm à 2 mm avec une température de fin de laminage de finition comprise entre 750°C et 300°C pour former une bande à chaud, en ce que l'on bobine ladite bande à chaud à une température comprise entre 650°C et 200°C, et en ce que l'on soumet ladite bande à chaud à au moins une étape de laminage à froid jusqu'à l'épaisseur finale désirée , avec un taux de réduction total inférieur ou égal à 95 %.
- Procédé suivant la revendication 8, caractérisé en ce que l'on refroidit l'acier après le laminage de dégrossissage pour assurer la transformation de phase de l'austénite en ferrite avant le laminage de finition et en ce que la durée de ce refroidissement est inférieure à 30 secondes.
- Procédé suivant l'une ou l'autre des revendications 8 et 9, caractérisé en ce que l'on bobine ladite bande à chaud à une température comprise entre 750°C et 200°C.
- Procédé suivant l'une ou l'autre des revendications 1 à 10, caractérisé en ce qu'on lamine à froid ladite bande à chaud en deux opérations, jusqu'à une épaisseur finale inférieure à 0,50 mm, et de préférence inférieure à 0,20 mm.
- Procédé suivant la revendication 11, caractérisé en ce que la première opération de laminage à froid confère à la bande une épaisseur inférieure à 0,5 mm avec un taux de réduction inférieur ou égal à 90 %.
- Procédé suivant l'une ou l'autre des revendications 11 et 12, caractérisé en ce que la seconde opération de laminage à froid confère à la bande à froid son épaisseur finale, avec un taux de réduction inférieur à 50 %, et de préférence inférieur à 30 %.
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
BE9100673 | 1991-07-17 | ||
BE9100673A BE1005143A6 (fr) | 1991-07-17 | 1991-07-17 | Procede de fabrication d'une bande mince en acier doux laminee a chaud. |
BE9100732A BE1005147A6 (fr) | 1991-08-09 | 1991-08-09 | Procede de fabrication d'une bande ultra-mince en acier laminee a froid. |
BE9100732 | 1991-08-09 |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0524162A2 EP0524162A2 (fr) | 1993-01-20 |
EP0524162A3 EP0524162A3 (en) | 1993-03-24 |
EP0524162B1 true EP0524162B1 (fr) | 1998-11-11 |
Family
ID=25662595
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP92870104A Revoked EP0524162B1 (fr) | 1991-07-17 | 1992-07-13 | Procédé de fabrication d'une bande mince en acier doux |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP0524162B1 (fr) |
DE (1) | DE69227548T2 (fr) |
Families Citing this family (15)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
BE1007790A6 (fr) * | 1993-12-20 | 1995-10-24 | Centre Rech Metallurgique | Procede pour fabriquer une bande mince en acier doux laminee a froid pour l'emboutissage. |
BE1007927A3 (fr) * | 1994-02-07 | 1995-11-21 | Cockerill Rech & Dev | Procede de production d'acier doux. |
FR2728490B1 (fr) * | 1994-12-21 | 1997-01-24 | Lorraine Laminage | Procede de fabrication d'une bande d'acier destinee a la fabrication par emboutissage et re-emboutissage de recipients en acier |
FR2730942B1 (fr) * | 1995-02-24 | 1997-05-16 | Lorraine Laminage | Procede d'elaboration d'une tole ou d'une bande en acier pour la realisation d'une boite et tole ou bande en acier obtenue par ce procede |
NL1000694C2 (nl) * | 1995-06-29 | 1997-01-08 | Hoogovens Staal Bv | Werkwijze en inrichting voor het vervaardigen van een vervormbare stalen band. |
DE19531538A1 (de) * | 1995-08-25 | 1997-02-27 | Schloemann Siemag Ag | Warmbandproduktionsanlage für ferritisches Walzen und Verfahren zur Erzeugung von ferritischem Walzband |
DE19600990C2 (de) * | 1996-01-14 | 1997-12-18 | Thyssen Stahl Ag | Verfahren zum Warmwalzen von Stahlbändern |
NL1003293C2 (nl) * | 1996-06-07 | 1997-12-10 | Hoogovens Staal Bv | Werkwijze en inrichting voor het vervaardigen van een stalen band. |
NL1007739C2 (nl) | 1997-12-08 | 1999-06-09 | Hoogovens Staal Bv | Werkwijze en inrichting voor het vervaardigen van een stalen band met hoge sterkte. |
BR9610708A (pt) * | 1996-06-28 | 1999-09-14 | Hoogovens Staal Bv | Método e instalação para a fabricação de uma tira ou folha de aço com estampagem profunda |
NL1007731C2 (nl) * | 1997-12-08 | 1999-06-09 | Hoogovens Staal Bv | Werkwijze en inrichting voor het vervaardigen van een ferritisch gewalste stalen band. |
DE19858073C2 (de) * | 1998-12-16 | 2003-04-24 | Max Planck Inst Eisenforschung | Verfahren zur Erzeugung von dünnen Warmbändern aus Stahl mit verbesserter Tiefziehfähigkeit |
JP3944579B2 (ja) * | 2003-05-20 | 2007-07-11 | 独立行政法人物質・材料研究機構 | 角型及びオーバルの孔型ロールを用いた多パス温間制御圧延方法 |
ITRM20060262A1 (it) * | 2006-05-17 | 2007-11-18 | Ct Sviluppo Materiali Spa | Procedimento per la produzione di nastri di acciaio al carbonio a grano fine e nastri cosi ottenibili |
EP2128277A1 (fr) * | 2008-05-29 | 2009-12-02 | Aga AB | Procédé pour le recuit de bandes métalliques |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0306076A1 (fr) * | 1987-09-01 | 1989-03-08 | Hoogovens Groep B.V. | Fabrication de bandes d'acier formables |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5967322A (ja) * | 1982-10-08 | 1984-04-17 | Kawasaki Steel Corp | 深絞り用冷延鋼板の製造方法 |
US4676844A (en) * | 1985-03-06 | 1987-06-30 | Kawasaki Steel Corporation | Production of formable thin steel sheet excellent in ridging resistance |
US4793401A (en) * | 1985-12-12 | 1988-12-27 | Kawasaki Steel Corporation | Method of producing thin steel sheets having an improved processability |
JPS63220903A (ja) * | 1987-03-10 | 1988-09-14 | Nkk Corp | 高珪素鋼の温間圧延における潤滑方法 |
-
1992
- 1992-07-13 DE DE1992627548 patent/DE69227548T2/de not_active Revoked
- 1992-07-13 EP EP92870104A patent/EP0524162B1/fr not_active Revoked
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0306076A1 (fr) * | 1987-09-01 | 1989-03-08 | Hoogovens Groep B.V. | Fabrication de bandes d'acier formables |
Also Published As
Publication number | Publication date |
---|---|
EP0524162A3 (en) | 1993-03-24 |
EP0524162A2 (fr) | 1993-01-20 |
DE69227548D1 (de) | 1998-12-17 |
DE69227548T2 (de) | 1999-07-29 |
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