System and method for the continuous casting and subsequent flat rolling of a steel strip

Abstract

A system 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. At least one hot rolling stand is coupled to the casting device, with which the raw steel strip can be roughed into the steel strip immediately after the casting process while still in the austenitic and/or ferritic microstructure range. At least one rolling module is arranged immediately after the hot rolling stand coupled to the casting device. The rolling module includes, in this order, a cooling device, a heating device and a hot rolling stand with which the roughed steel strip can be hot-rolled in the austenitic and/or ferritic microstructure range to specifications into the steel strip.

Claims

1-9. (canceled)

10. A system (1) for the continuous casting and subsequent flat rolling of a steel strip (2) with an austenitic and/or ferritic microstructure and a thickness of less than 1.0 mm, comprising a casting device (3) with which a raw steel strip (4) with a thickness in the range of 1.50 to 4.0 mm can be continuously cast; at least one hot rolling stand (6) coupled to the casting device (3) with which the raw steel strip (4) can be roughed into the steel strip (2) immediately after the casting process while still in the austenitic and/or ferritic microstructure range; and at least one rolling module (7) arranged immediately after the hot rolling stand (6) coupled to the casting device (3), wherein the at least one rolling module (7) includes, in this order, a cooling device (8), a heating device (9), and a hot rolling stand (10) with which the roughed steel strip (2) can be hot-rolled to specifications in the austenitic and/or in the ferritic microstructure range into the steel strip (2).

11. The system (1) according to claim 10, wherein at least one cooling section (11) is provided after the at least one rolling module (7).

12. The system (1) according to claim 10, wherein the at least one rolling module (7) comprises at least two rolling modules (7, 15) respectively arranged one behind the other, wherein each of the at least two rolling modules (7, 15) includes, in this order, a cooling device (8, 16), a heating device (9, 17), and a hot rolling stand (10, 18).

13. The system (1) according to claim 10, wherein the at least one rolling module (7) comprises at least three rolling modules (7, 15) respectively arranged one behind the other, wherein each of the at least three rolling modules (7, 15) includes, in this order, a cooling device (8, 16), a heating device (9, 17), and a hot rolling stand (10, 18).

14. The system (1) according to claim 10, wherein at least one cooling section (11) is provided after a last rolling module (15) of the at least three rolling modules (7, 15).

15. The system (1) according to claim 10, further comprising at least one heating device (5) arranged before the hot rolling stand (6) coupled to the casting device (3).

16. The system (1) according to claim 10, further comprising a pickling device for pickling and/or a heat treatment device for annealing the steel strip (2) arranged after the at least one rolling module (7).

17. The system (1) according to claim 13, further comprising a pickling device for pickling and/or a heat treatment device for annealing the steel strip (2) arranged after a last rolling module (15) of the at least three rolling modules (7, 15).

18. The system (1) according to claim 10, further comprising at least one coiling device (13, 14) for coiling the steel strip (2) into a coil.

19. The system (1) according to claim 10, further comprising at least two, coiling devices (13, 14) for coiling the steel strip (2) into a coil.

20. The system (1) according to claim 18, further comprising a separating device (12) arranged before the at least one coiling device (13, 14) for separating the steel strip (2).

21. A method for manufacturing a steel strip (2) with an austenitic and/or ferritic microstructure and a thickness of less than 1.0 mm, comprising: continuously casting a raw steel strip (4) with a thickness in the range of 1.50 to 4.0 mm in a casting device (3); then roughening the steel strip (4) directly in the austenitic and/or ferritic microstructure range, preferably above a temperature of at least 700? C., into the steel strip (2) by at least one hot rolling stand (6) coupled to the casting device (3); and hot-rolling the roughed steel strip (2) in austenitic and/or ferritic conditions to specifications into the steel strip (2) via at least one rolling module (7), which includes, in this order, a cooling device (8), a heating device (9), and a hot rolling stand (10), and which is arranged immediately after the hot rolling stand (6) coupled to the casting device (3).

22. The method according to claim 21, wherein roughening the steel strip (4) in the austenitic and/or ferritic microstructure range is performed at a temperature above 700? C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] 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.

[0022] FIG. 1 shows a first variant embodiment of the system for the continuous casting and subsequent flat rolling of a steel strip (2) with an austenitic and/or ferritic microstructure.

[0023] FIG. 2 shows a second variant embodiment of the system for the continuous casting and subsequent flat rolling of a steel strip (2) with an austenitic and/or ferritic microstructure.

DETAILED DESCRIPTION

[0024] FIG. 1 shows a variant embodiment of a system 1 by means of which it is possible to manufacture a steel strip 2 with an austenitic and/or ferritic microstructure with a thickness of less than 1.0 mm by continuous casting and subsequent flat rolling.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] FIG. 2 shows a second variant embodiment of the system 1 according to the invention, which, in contrast to the first variant embodiment, comprises a second rolling module 15, which in this scenario includes a second cooling device 16, a third heating device 17 as well as a third hot rolling stand 18 via which a rolling in the austenitic and/or ferritic microstructure range is rendered possible.

EXAMPLES

Example 1

[0029] 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 FIG. 1. The raw steel strip 4 had a temperature of 1250? C. upon exiting the casting device 3 and was then heated from an entry temperature of 1157? C. to 1246? C. via an induction heater 5. The raw steel strip 4 was then roughed in austenitic conditions at a rolling speed of 2.52 m/s in the first hot rolling stand 6 with a reduction of 55%, wherein the entry temperature was 1130? C. and the exit temperature was 971? C. The thus obtained 0.9 mm thick, austenitically roughed steel strip 2 was then rolled to specifications via the first rolling module 7 by first heating it from 938? C. to a temperature of 1051?? C. via the induction heater 9 before it was hot-rolled to specifications in austenitic conditions at a rolling speed of 3.78 m/s in the second hot rolling stand 10 with a reduction of 33%. The entry temperature into the second hot rolling stand 10 was 992? C. and the exit temperature was 882? C. The thus obtained steel strip 2, which had a final strip thickness of 0.6 mm, was then cooled and wound into a coil.

Example 2

[0030] 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 FIG. 1. The raw steel strip 4 had a temperature of 1250? C. upon exiting the casting device 3 and, due to the sufficiently high temperature, was fed without heating to the hot rolling stand 6 where it was roughed in austenitic conditions at a rolling speed of 2.22 m/s with a reduction of 55%, wherein the entry temperature was 1020? C. and the exit temperature was 882? C. The thus obtained 0.9 mm thick, austenitically roughed steel strip 2 was then rolled in ferritic conditions to specifications via the first rolling module 7 by first cooling it from 794? C. to a temperature of 785? C. via the cooling device 8 and then hot-rolled to specifications at a rolling speed of 3.33 m/s in the second hot rolling stand 10 with a reduction of 33%. The entry temperature into the second hot rolling stand 10 was 757? C. and the exit temperature was 705?? C. The thus obtained steel strip 2, which had a final strip thickness of 0.6 mm, was then cooled and wound into a coil.

REFERENCE SIGNS

[0031] 1 System [0032] 2 Steel strip [0033] 3 Casting device [0034] 4 Raw steel strip [0035] 5 First heating device/induction heater [0036] 6 First hot rolling stand [0037] 7 (First) rolling module [0038] 8 First cooling device [0039] 9 Second heating device/induction heater [0040] 10 Second hot rolling stand [0041] 11 Cooling section/spray cooling [0042] 12 Separating device/ [0043] 13 First coiling device [0044] 14 Second coiling device [0045] 15 Second rolling module [0046] 16 Second cooling device [0047] 17 Third heating device [0048] 18 Third rolling stand