Patent Application
20240278298
The present invention relates to a system and to a method for the continuous casting and subsequent flat rolling of a steel strip with an austenitic and/or ferritic microstructure and a thickness of less than 1.0 mm.
Steel strips with an austenitic and/or ferritic microstructure and a thickness of less than 1.0 mm, particularly with a thickness in the range of 0.40 to 0.60 mm, are usually produced by cold-rolling hot strips in separate cold rolling mills so that at least two or three processing steps are necessary to manufacture such thin steel strips with an austenitic and/or ferritic microstructure.
The German publication DE 11 2013 000841 T5 discloses a system for manufacturing thin steel strips, wherein a cast strip with a thickness of 1 to 5 mm can be cast and hot-rolled directly in a hot rolling mill into a thin steel strip; such a system, however, does not allow the targeted manufacture of steel strips with an austenitic and/or ferritic microstructure.
An object of the present disclosure is to provide an improved system vis-à-vis the prior art as well as an improved method vis-à-vis the prior art, in particular to provide a system or method which enables the manufacture of a steel strip with an austenitic and/or ferritic microstructure and with a thickness of less than 1.0 mm.
The object is achieved by means of a system and a method as described herein.
The system, which is provided and/or suitable for the continuous casting and subsequent flat rolling of a steel strip with an austenitic and/or ferritic microstructure and a thickness of less than 1.0 mm, comprises a casting device with which a raw steel strip with a thickness in the range of 1.50 to 4.0 mm can be continuously cast, as well as at least one hot rolling stand which is coupled to the casting device and with which the raw steel strip can be roughed immediately after the casting process into the steel strip while still in the austenitic and/or ferritic microstructure range.
The system comprises at least one rolling module arranged immediately after the hot rolling stand coupled to the casting device, which rolling module includes, in this order, a cooling device, a heating device as well as a hot rolling stand with which the roughed steel strip in the austenitic and/or in the ferritic microstructure range can be hot-rolled to specifications into the steel strip.
Analogously, the present invention provides a method for manufacturing a steel strip with an austenitic and/or ferritic microstructure and with a thickness of less than 1.0 mm, wherein a raw steel strip with a thickness in the range of 1.50 to 4.0 mm is first continuously cast in a casting device and then roughed directly in the austenitic and/or ferritic microstructure range, preferably above a temperature of at least 700° C., into the steel strip by means of at least one hot rolling stand coupled to the casting device.
The steel strip that has been roughed in the austenitic and/or in the ferritic microstructure range is then hot-rolled to specifications into the steel strip via at least one rolling module, which includes, in this order, a cooling device, a heating device and a hot rolling stand, and which is arranged immediately after the hot rolling stand coupled to the casting device.
The system or method facilitates an improved economic efficiency in hot strip production, in particular in the production of ultra-thin hot strip, since it is possible to significantly reduce delivery times, lower investment costs and achieve substantial energy savings through the reduction of the number of process steps.
The combination in the term “austenitic and/or ferritic microstructure” is understood in the sense of the present invention to mean that the steel strip to be manufactured possesses an austenitic or a ferritic microstructure at the end of the process and can be rolled in austenitic as well as ferritic conditions during manufacture. In other words, the steel strip to be manufactured essentially does not exhibit a mixed structure that includes an austenitic and a ferritic structure at the end of the process.
The term “ultra-thin hot-rolled strip” is understood in the sense of the present invention to mean a steel strip that has a thickness of less than 1.0 mm, preferably a thickness of less than 0.80 mm, particularly preferably a thickness in the range of 0.40 to 0.60 mm. Most preferably, the steel strip exhibiting an austenitic and/or ferritic microstructure has a thickness of 0.4 mm.
It is also possible to provide an austenitic and/or ferritic microstructure in the steel strip in a targeted manner via the at least one rolling module. In order to produce, for example, a ferritic microstructure in the steel strip, the austenitically or ferritically roughed steel strip is cooled via the cooling device before then being rolled in ferritic conditions to specifications in the rolling stand of the rolling module, preferably in a temperature range of 700 to 780° C. If, on the other hand, an austenitic microstructure is to be provided in the steel strip, then the austenitically or ferritically roughed steel strip is heated via the heating device before being rolled in austenitic conditions to specifications in the rolling stand of the rolling module, preferably above a temperature of 850° C.
Further advantageous embodiments are indicated in the dependent claims. The individual features listed in the dependent claims can be combined with one another in a technologically meaningful manner and can define further embodiments of the invention. The features indicated in the claims are also elucidated and explained in the description, wherein further preferred embodiments of the invention are described.
In an advantageous variant embodiment, the system can comprise at least two, more preferably at least three, rolling modules arranged one behind the other, wherein each of the rolling modules respectively includes, in this order, a cooling device, a heating device and a hot rolling stand in order to respectively enable a hot rolling in an austenitic and/or ferritic microstructure range. This allows the total degree of deformation in the respective austenitic and/or ferritic microstructure to be varied by the number of implemented deformations, whereby the quality parameters of the steel strip can be advantageously influenced.
In a further advantageous variant embodiment, the system can also comprise a heating device arranged between the casting device and the hot rolling stand coupled to the casting device in order to enable a targeted intermediate heating of the raw steel strip arriving from the casting device before it is roughed in austenitic conditions in the hot rolling stand.
Preferably, the system comprises, after the at least one rolling module and particularly preferably after the last rolling module, at least one cooling section over which the steel strip is cooled to a coiling temperature. In this connection, it is advantageously provided that the system comprises at least one coiling device, more preferably at least two coiling devices, via which the completed steel strip is wound into a coil. The system usually further comprises a separating device arranged before the coil device for separating the steel strip.
In a further variant embodiment, the system can also comprise a pickling device for pickling and/or a heat treatment device for annealing the steel strip, which is then arranged between the, preferably last, rolling module and the cooling section.
In a further aspect, the present invention also relates to the use of the system according to the invention for the targeted manufacture of a steel strip with an austenitic and/or ferritic microstructure and a thickness of less than 1.0 mm, preferably with a thickness of less than 0.80 mm, particularly preferably with a thickness in the range of 0.40 to 0.60 mm.
The invention and the technical context are explained in more detail in the following with reference to the figures. It should be noted that it is not intended for the invention to be limited by the illustrated example embodiments. In particular, unless explicitly stated otherwise, it is also possible to combine elements of the subject matter illustrated in the figures with other elements and findings in the present description and/or figures. In particular, it should be noted that the figures and in particular the illustrated size ratios are only schematic. Identical reference signs designate identical objects so that explanations relating to other figures may be applicable.
In the illustrated variant embodiment, the system 1 comprises a casting device 3 which is continuously supplied with molten steel. A raw steel strip 4 with a thickness in the range of 1.50 to 4.0 mm is first continuously cast via the casting device 3. Arranged behind the casting device 3 in the direction of travel of the strip is a first heating device 5 via which the raw steel strip 4 can be heated before the first rolling pass in cases where the temperature is below 700° C. and/or the first deformation step is to be carried out in the austenitic microstructure range. The first heating device 5 can be implemented, for example, in the form of an inductive heating device. The system 1 further comprises a first hot rolling stand 6 coupled directly to the casting device 3. By the term “coupled directly” it is understood in the sense of the present invention that the first hot rolling stand 6 is arranged directly behind the casting device 3 in the direction of travel of the strip so that the raw steel strip 4 produced by the casting device 3 can be roughed directly and thus in the austenitic and/or ferritic microstructure range.
The system 1 further comprises, behind the first hot rolling stand 6 in the direction of travel of the strip, a first rolling module 7 which includes, in this order, a first cooling device 8, a second heating device 9 as well as a second hot rolling stand 10 with which the austenitically or ferritically roughed steel strip 2 is hot-rolled in the austenitic and/or ferritic microstructure range to specifications into the steel strip 2. The second heating device 9 can also be implemented, for example, in the form of an inductive heating device. The first cooling device 10 can be implemented, for example, in the form of an intermediate cooling between stands.
Behind the first rolling module 7 in the direction of travel of the strip, the system 1 first comprises a cooling section 11, which is preferably implemented in the form of a spray cooling and by means of which the steel strip 2 that has been rolled to the desired final strip thickness, for example a final strip thickness of 0.4 mm, can be gently cooled on account of the extremely small thickness. The steel strip 2 subsequently passes through a separating device 12, which can consist of, for example, a flying shear, and is wound into a coil via a first and/or a second coiling device 13, 14.
To manufacture a steel strip 2 with a purely austenitic microstructure, a raw steel strip 4 with a thickness of 2.0 mm and a width of 1100 mm was first cast by means of the system 1 shown in
In order to manufacture a steel strip 2 with a purely ferritic microstructure, a raw steel strip 4 with a thickness of 2.0 mm and a width of 1100 mm was first cast by means of the system 1 shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2020 211 273.8 | Sep 2020 | DE | national |
| 10 2021 209 879.7 | Sep 2021 | DE | national |
This application is a national stage application, filed under 35 U.S.C. § 371, of International Patent Application No. PCT/EP2021/074656, filed on 8 Sep. 2021, which claims the benefit of German Patent Application No. 10 2020 211 273.8, filed 8 Sep. 2020, and German Patent Application No. 10 2021 209 879.7, filed 8 Sep. 2021.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/074656 | 9/8/2021 | WO |
