Method for producing a steel component provided with a coating, and steel component

Patent metadata

Field	Value
Publication number	US-11401574-B2
Application number	US-201816624555-A
Country	US
Kind code	B2
Filing date	Jun 19, 2018
Priority date	Jun 29, 2017
Publication date	Aug 2, 2022
Grant date	Aug 2, 2022

Abstract

The invention relates to a method for producing a steel component by forming of a flat steel product coated with an anticorrosion coating, and to a steel component produced from a steel substrate coated with anticorrosion coating. The steel component is produced by providing a flat steel product coated with an aluminum-based anticorrosion coating, heat-treating a blank formed from the coated flat steel product, in a furnace, where 0.0034° C./min≤Q≤0.021° C./min, with Q=(T*d)/(t*L), T=furnace temperature in ° C., d=blank thickness in mm, t=dwell time of the blank in the furnace in min, L=furnace length in m, and shaping the blank in a shaping tool. The steel component comprises a steel substrate and, at least on one side of the steel substrate, an anticorrosion coating which comprises at least one first and one second silicon-rich layer (Si1, Si2) and also one first and one second low-silicon layer (A, B), where the quotient X formed from the thickness (dB) of the second low-silicon layer (B) in μm by the thickness (dA) of the first low-silicon layer (A) in μm is at least 0.4 and at most 1.1.

First claim

What is claimed is:

1. A method for producing a steel component coated with an anticorrosion coating, comprising the following operating steps:
a) providing a flat steel product coated with an aluminum-based anticorrosion coating,
b) heat-treating a blank formed from the coated flat steel product, in a furnace, where:
0.0034° C./min≤Q≤0.021° C./min

with Q=(T*d)/(t*L), where
T=furnace temperature in ° C.,
d=blank thickness in mm,
t=dwell time of the blank in the furnace in min,
L=furnace length in mm; and

c) shaping the blank in a shaping tool to form a steel component,
wherein said heat treating step changes the composition of the aluminum-based anticorrosion coating such that the aluminum-based anticorrosion coating includes a first silicon-rich layer, which contains more than 4 and up to 8 wt % of Si, that is the outermost layer of the aluminum-based anticorrosion coating.

2. The method as claimed in claim 1 , wherein the temperature T of the furnace is at least 830° C. and at most 980° C.

3. The method as claimed in claim 2 wherein the blank is moved through the furnace during operating step b) with an average velocity (vP) of at least 1.5 m/min and at most 25 m/min.

4. The method as claimed in claim 1 wherein the dwell time t of the blank in the furnace is at least 1 min and at most 18 min.

5. The method as claimed in claim 1 wherein the aluminum-based anticorrosion coating contains 3-15 wt % of silicon, up to 3.5 wt % of iron, the balance being aluminum and unavoidable impurities.

6. The method as claimed in claim 1 wherein the Si content of the aluminum-based anticorrosion coating is 7-12 wt %.

7. The method as claimed in claim 1 wherein the Si content of the aluminum-based anticorrosion coating is 9-10 wt %.

8. The method as claimed in claim 1 wherein the Fe content of the aluminum-based anticorrosion coating is 1-3.5 wt %.

9. The method as claimed in claim 1 wherein that the Fe content of the aluminum-based anticorrosion coating is 2-3.5 wt %.

10. The method as claimed in claim 1 wherein the blank is cooled in operating step c) in the forming tool at a cooling rate (CR) of at least 20 K/s and at most 1000 K/s.

11. The method of claim 1 , wherein said heat treating step changes the composition of the aluminum-based anticorrosion coating to further include:
a second silicon-rich layer, which contains more than 4 and up to 8 wt % of Si, disposed between the first silicon-rich layer and the flat steel product;
a first low silicon layer, which contains 1-4 wt % of Si, disposed between the first and second silicon-rich layers; and
a second low silicon layer, which contains 0.5-4 wt % of Si, disposed between the second silicon-rich layer and the flat steel product.

12. The method of claim 11 , wherein:
the first silicon-rich layer, which besides unavoidable impurities, further contains 40-70 wt % of Fe, up to 1 wt % of Mn and 30-60 wt % of aluminum;
the first low-silicon layer, which besides unavoidable impurities, further contains 30-60 wt % of Fe, up to 1 wt % of Mn and 40-60 wt % of aluminum;
the second silicon-rich layer, which besides unavoidable impurities, further contains 40-70 wt % of Fe, up to 1 wt % of Mn and 20-50 wt % of aluminum; and
the second low-silicon layer, which besides unavoidable impurities, further contains 40-97 wt % of Fe, 0.5-1.5 wt % of Mn and 2-40 wt % of aluminum.

13. The method of claim 12 , wherein said heat treating step changes the composition of the aluminum-based anticorrosion coating to further include a third low-silicon layer, which contains 0-4 wt % Si, disposed on the first silicon-rich layer such that the third low-silicon layer is the outermost layer of the anticorrosion coating instead of the first silicon-rich layer.

14. The method of claim 12 , wherein the heat treating step changes the composition of the aluminum-based anticorrosion coating to further include an oxide layer containing silicon oxides and/or aluminum oxides having a thickness of between 50 nm and 250 nm,
wherein the oxide layer is the outermost layer of the anticorrosion coating instead of the first silicon-rich layer, and
wherein a ratio X of a thickness (dB) of the second low-silicon layer in μm to a thickness (dA) of the first low-silicon layer in μm is at least 0.4 and at most 1.1.

15. A method for producing a steel component coated with an anticorrosion coating, comprising the following operating steps:
(a) providing a flat steel product coated with an aluminum-based anticorrosion coating,
(b) heat-treating a blank formed from the coated flat steel product, in a furnace, to change the composition of the anticorrosion coating to produce:
a first silicon-rich layer containing more than 4 and up to 8 wt % of Si, 40-70 wt % of Fe, up to 1 wt % of Mn and 30-60 wt % of aluminum;
a second silicon-rich layer being disposed between the first silicon-rich layer and the flat steel product, and containing more than 4 and up to 8 wt % of Si, 40-70 wt % of Fe, up to 1 wt % of Mn and 20-50 wt % of aluminum;
a first low silicon layer being disposed between the first and second silicon-rich layers, and containing 1-4 wt % of Si, 30-60 wt % of Fe, up to 1 wt % of Mn and 40-60 wt % of aluminum; and
a second low silicon layer being disposed between the second silicon-rich layer and the flat steel product, and containing 0.5-4 wt % of Si, 40-97 wt % of Fe, 0.5-1.5 wt % of Mn and 2-40 wt % of aluminum; and

(c) shaping the blank in a shaping tool to form a steel component.

Assignees

• Thyssenkrupp Steel Europe Ag
• Thyssenkrupp Ag

Inventors

• Ruthenberg Manuela
• Koyer Maria

Classifications

• C23C2/12

  Aluminium or alloys based thereon · CPC title

• C22C21/00

  Alloys based on aluminium · CPC title

• C22C38/28

  with titanium or zirconium · CPC title

• C21D6/008

  containing Si · CPC title

• C22C38/14

  containing titanium or zirconium · CPC title