Method for Producing A Cold-Rolled Flat Steel Product for Deep-Drawing and Ironing Applications, Flat Steel Product, and Use of a Flat Steel Product of Said Type

• US 20160010172A1
• Filed: 03/06/2014
• Published: 01/14/2016
• Est. Priority Date: 03/07/2013
• Status: Active Grant

• Current Assignee: ThyssenKrupp Rasselstein GmbH (Thyssenkrupp AG), Thyssenkrupp Steel Europe AG (Thyssenkrupp AG)
• Original Assignee: ThyssenKrupp Rasselstein GmbH (Thyssenkrupp AG), Thyssenkrupp Steel Europe AG (Thyssenkrupp AG)
• Inventors: Sowka, Eberhard, Kaup, Burkhard, Holleck, Erhard, Schiester, Stephan
• Granted Patent: US 10,184,159 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B21B 1/22 for rolling plates, strips, bands or sheets of indefinite length B21B1/42 takes precedence
• CPC Class Codes: B21B 1/46 for rolling metal immediately subsequent to continuous casting metal-rolling stands B21B13/22; continuous casting B22D11/00, e.g. into moulds with rolls B22D11/06
• CPC Class Codes: B21D 35/005 characterized by the material of the blank or the workpiece B21D26/053 takes precedence
• CPC Class Codes: B21D 51/26 cans or tins; Closing same in a permanent manner making outlet arrangements B21D51/38; welding or soldering B23K
• CPC Class Codes: B22D 11/1206 for plastic shaping of strands rolling mills B21B1/46
• CPC Class Codes: B22D 11/126 for cutting
• CPC Class Codes: B22D 11/14 Plants for continuous casting
• CPC Class Codes: C21D 1/26 Methods of annealing
• CPC Class Codes: C21D 6/005 containing Mn
• CPC Class Codes: C21D 6/008 containing Si
• CPC Class Codes: C21D 8/041 involving a particular fabrication or treatment of ingot or slab
• CPC Class Codes: C21D 8/0426 Hot rolling
• CPC Class Codes: C21D 8/0436 Cold rolling
• CPC Class Codes: C21D 8/0463 following hot rolling
• CPC Class Codes: C22B 9/04 Refining by applying a vacuum
• CPC Class Codes: C22B 9/10 with refining or fluxing agents; Use of materials therefor, e.g. slagging or scorifying agentsC22B9/18 takes precedenceC22B9/006 takes precedence
• CPC Class Codes: C22C 38/001 containing N
• CPC Class Codes: C22C 38/004 Very low carbon steels, i.e. having a carbon content of less than 0,01%
• CPC Class Codes: C22C 38/02 containing silicon
• CPC Class Codes: C22C 38/04 containing manganese
• CPC Class Codes: C22C 38/06 : containing aluminium
• CPC Class Codes: C25D 5/36 : of iron or steel

Abstract

A method is disclosed for the operationally reliable production of a cold-rolled flat steel product of ≦0.5 mm in thickness for deep-drawing and ironing applications. In the method, a steel melt which (in wt %) comprises up to 0.008% C, up to 0.005% Al, up to 0.043% Si, 0.15-0.5% Mn, up to 0.02% P, up to 0.03% S, up to 0.020% N and in each case optionally up to 0.03% Ti and up to 0.03% Nb and, as a remainder, iron and unavoidable impurities, is, with the omission of a Ca treatment, subjected to a secondary metallurgical treatment which, in addition to a vacuum treatment, comprises a ladle furnace treatment and during which the steel melt to be treated is kept under a slag, the Mn and Fe contents of which are, in sum total, <15 wt %. From the steel melt, a thin slab or a cast strip are produced, which are subsequently hot-rolled to form a hot strip with a thickness of <2.5 mm and wound to form a coil. Subsequently, the hot strips are cold-rolled to form a flat steel product of up to 0.5 mm in thickness.

Claims

1. A method for producing a cold-rolled flat steel product of up to 0.5 mm in thickness for deep-drawing and ironing applications, comprising the following working steps:

a) producing a metal melt which (in wt %) comprises up to 0.008% C, up to 0.005% Al, up to 0.043% Si, 0.15-0.5% Mn, up to 0.02% P, up to 0.03% S, up to 0.020% N and in each case optionally up to 0.03% Ti and up to 0.03% Nb and, as a remainder, iron and unavoidable impurities, the contents of which are to be attributed to up to 0.08% Cr, up to 0.08% Ni, up to 0.08% Cu, up to 0.02% Sn, up to 0.01% Mo, up to 0.0020% V, up to 0.007% B, up to 0.05% Co and up to 0.0060% Ca, wherein the steel melt is, with the omission of a Ca treatment, subjected to a secondary metallurgical treatment which, in addition to a vacuum treatment, comprises a ladle furnace treatment and during which the steel melt to be treated is kept under a slag, the Mn content % Mn and Fe content % Fe are defined by % Mn+% Fe<

15 wt %;

b) continuously casting the metal melt to form a strand, and severing a thin slab from the strand, or to form a cast strip;

c) hot-rolling the thin slab or the cast strip to form a hot strip with a thickness of less than 2.5 mm;

d) winding the hot strip to form a coil; and

e) cold-rolling the hot strip to form the cold-rolled flat steel product of up to 0.5 mm in thickness.

2. The method as claimed in claim 1, in thatwherein the Al content of the steel melt amounts to at most 0.002 wt %.

3. The method as claimed in claim 1, wherein the Fe content % Fe of the slag under which the steel melt is kept during the ladle furnace treatment amounts to less than 10 wt %.

4. The method as claimed in claim 1, wherein the oxygen content of the steel melt at the end of the ladle furnace treatment lies below 100 ppm.

5. The method as claimed in claim 1, wherein the thin slab is, before the hot rolling, brought to a temperature of 1000-1250°

C.

6. The method as claimed in claim 1, wherein the hot-rolling start temperature of the thin slab at the start of the hot-rolling process is 950-1200°

C.

7. The method as claimed in claim 1, wherein the hot-rolling end temperature of the hot strip at the end of the hot-rolling process is 800-950°

C.

8. The method as claimed in claim 1, wherein the hot strip is wound at a winding temperature of 500-750°

C.

9. The method as claimed in claim 1, wherein the thickness of the cold-rolled flat steel product amounts to less than 0.26 mm.

10. The method as claimed in claim 1, wherein the cold rolling is performed in at least two stages, and the cold-rolled flat steel product is subjected to recrystallization annealing between the stages of the cold-rolling process.

11. The method as claimed in claim 10, wherein the degree of deformation achieved by way of the first stage of the cold-rolling process is greater than 85%, and the degree of deformation achieved by way of the second stage of the cold-rolling process amounts to 0.4-50%.

12. The method as claimed in claim 1, wherein the cold-rolled flat steel product is subjected to electrolytic tin plating.

13. A flat steel product produced through the use of the method configured as claimed in claim 1.

14. The use of a flat steel product as claimed in claim 13 for the production of cans for foodstuffs, animal feed, beverages or other filling materials, such as chemical or biological products, or for the production of aerosol cans, closures, crown caps or spray cans.

15. The use of a flat steel product as claimed in claim 13 for deformation applications in which the earing, as defined in accordance with ISO 11531, is <

0.86 mm.