Cold-rolled flat steel product for deep drawing applications and method for production thereof

Patent metadata

Field	Value
Publication number	US-10131976-B2
Application number	US-201414767770-A
Country	US
Kind code	B2
Filing date	Feb 13, 2014
Priority date	Feb 14, 2013
Publication date	Nov 20, 2018
Grant date	Nov 20, 2018

Abstract

A cold-rolled flat steel product for deep drawing applications is disclosed, composed of a steel which, in addition to Fe and unavoidable impurities (in % by weight) contains C: <0.1%, Al: 6.5-11%, REM: 0.02-0.2%, P: <0.1%, S: <0.03%, N: <0.1% and optionally one or more elements from the group of “Mn, Si, Nb, Ti, Mo, Cr, Zr, V, W, Co, Ni, B, Cu, Ca, N”, provided that Mn: <6%, Si: <1%, Nb: <0.3%, Ti: <0.3%, Zr: <1%, V: <1%, V: <1%, Mo: <1%, Cr: <3%, Co: <1%, Ni: <2%, B: <0.1%, Cu: <3%, Ca: <0.015%. For production of such a flat steel product, a steel of appropriate composition is cast to give a pre-product, which is then hot-rolled to hot strip at a hot rolling end temperature of 820-1000° C. The latter is subsequently wound at a winding temperature of up to 850° C., after winding annealed at an annealing temperature of >650-1200° C. for 1-50 h, then cold-rolled in one or more stages with a total cold rolling level of ≥30% to give the cold-rolled flat steel product and finally annealed at 650-850° C.

First claim

The invention claimed is:

1. A cold-rolled flat steel product for deep drawing applications, consisting of a steel containing, in addition to iron and unavoidable impurities (in % by weight):
C: up to 0.1%,
Al: 6.5-11%,
P: up to 0.1%,
S: up to 0.03%,
N: up to 0.1%,
at least one rare earth metal selected from the group consisting of Ce and La, provided that the content of rare earth metals thereof is 0.02%-0.2% by weight,
wherein for the contents of cerium and lanthanum with respect to the content of oxygen, which is as a result of the production absorbed in the steel product fulfills the condition:
0.5≤(% Ce+% La)/% O≤0.8,

where % Ce=respective cerium content, % La=respective lanthanum content, and % O=respective oxygen content of the steel, in each case reported in atom %,
wherein the cold-rolled flat steel product has an r value of at least 1, and
wherein the microstructure of the cold-rolled flat steel product contains 0% to 0.1% by volume of κ-carbides.

2. The flat steel product as claimed in claim 1 , wherein the Al content thereof is more than 6.7% by weight.

3. The flat steel product as claimed in claim 2 , wherein the Al content thereof is 8%-11% by weight.

4. The flat steel product as claimed in claim 1 , wherein the C content thereof is not more than 0.05% by weight.

5. The flat steel product as claimed in claim 1 , wherein the content of rare earth metals thereof is 0.06%-0.12% by weight.

6. The flat steel product as claimed in claim 1 , further containing one or more elements from the group of “Mn, Si, Nb, Ti, Mo, Cr, Zr, V, W, Co, Ni, B, Cu, Ca, N”, provided that
Mn: up to 6%,
Si: up to 1%,
Nb: up to 0.3%,
Ti: up to 0.3%,
Zr: up to 1%,
V: up to 1%,
W: up to 1%,
Mo: up to 1%,
Cr: up to 3%,
Co: up to 1%,
Ni: up to 2%,
B: up to 0.1%,
Cu: up to 3%, and
Ca: up to 0.015%.

Assignees

• Thyssenkrupp Steel Europe Ag

Inventors

• Dorner Dorothée
• Höckling Christian
• Hofmann Harald
• Miller magnus
• Schirmer Matthias
• Schwabe Jonas
• Zimmermann Alexander

Classifications

• C21D8/04

  to produce plates or strips for drawing, e.g. for deep-drawing · CPC title

• C21D8/0463

  following hot rolling · CPC title

• C22C38/48

  with niobium or tantalum · CPC title

• C22C38/44

  with molybdenum or tungsten · CPC title

• C22C38/50 Primary

  with titanium or zirconium · CPC title