Flat steel product with an Al-coating, method for producing the same, steel component and method for producing the same

Patent metadata

Field	Value
Publication number	US-10669603-B2
Application number	US-201515509167-A
Country	US
Kind code	B2
Filing date	Aug 26, 2015
Priority date	Sep 5, 2014
Publication date	Jun 2, 2020
Grant date	Jun 2, 2020

Abstract

A flat steel product for hot forming may be produced from a steel substrate that includes a steel comprising 0.1-3% by weight Mn and up to 0.01% by weight B, along with a protective coating that is applied to the steel substrate. The protective coating may be based on Al and may contain up to 20% by weight of other alloy elements. Also disclosed are methods for producing such flat steel products, steel components, and methods for producing steel components. Absorption of hydrogen is minimized during heating necessary for hot forming. This is achieved at least in part through an alloy constituent of 0.1-0.5% by weight of at least one alkaline earth or transition metal in the protective coating, wherein an oxide of the alkaline earth or transition metal is formed on an outer surface of the protective coating during hot forming of the flat steel product.

First claim

What is claimed is:

1. A flat steel product for hot forming that comprises:
a steel substrate from a steel that includes 0.1-3% by weight Mn and 0.0005%-0.01% by weight B; and
a protective coating applied to the steel substrate, the protective coating comprising 3-15% by weight Si, 0.31-0.5% by weight in total of alloy constituents which have a greater affinity for oxygen than Al, and the remainder Al,
wherein at least two of the alloy constituents are elements selected from the group consisting of alkaline earth and transition metals,
wherein the Mg content of the protective coating is 0.3-0.5% by weight and the Ca content of the protective coating is 0.01-0.5% by weight, and
wherein an oxide of the at least two elements selected from the group consisting of alkaline earth and transition metals is formed on an outer surface of the protective coating during hot forming of the flat steel product.

2. The flat steel product of claim 1 wherein an Mg content of the protective coating is 0.3%-0.4% by weight.

3. The flat steel product of claim 1 wherein, in addition to the alloy constituents, the protective coating includes up to 20% by weight of other alloy elements.

4. The flat steel product of claim 1 wherein the protective coating includes up to 5% by weight Fe.

5. The flat steel product of claim 1 wherein the protective coating is a hot dip coating.

6. A steel component produced by hot press forming the flat steel product of claim 1 , wherein the oxide of the at least two elements selected from the group consisting of alkaline earth and transition metals is formed on an outer surface of the protective coating during hot forming of the flat steel product.

7. The steel component of claim 6 wherein the alloy constituents are present in a layer that forms a finish of the protective coating relative to surroundings and that has a thickness of up to 200 nm.

8. A method for producing a steel product, the method comprising:
providing a steel substrate in a form of a flat steel product produced from a steel that comprises 0.1-3% by weight Mn and 0.0005-0.01% by weight B;
coating the steel substrate with a coating that comprises 3-15% by weight Si, 0.31-0.5% by weight in total of alloy constituents which have a greater affinity for oxygen than Al, and the remainder Al, wherein at least two of the alloy constituents are elements selected from the group of alkaline earth and transition metals, and wherein the Mg content of the protective coating is 0.3-0.5% by weight and the Ca content of the protective coating is 0.01-0.5% by weight; and
forming an oxide of the at least two alloy constituents selected from the group of alkaline earth and transition metals on an outer surface of the Al-based protective coating during hot forming of the flat steel product.

9. The method of claim 8 wherein the Al-based protective coating is applied to the steel substrate by hot dip coating.

10. The method of claim 8 wherein, in addition to the alloy constituents, the Al-based protective coating further comprises up to 20% by weight of other alloy elements.

11. A method for producing a steel component produced by hot press forming a flat steel product that comprises a steel substrate comprising steel that includes 0.1-3% by weight Mn and 0.0005-0.01% by weight B, and a protective coating applied to the steel substrate, wherein the protective coating comprises 3-15% by weight Si, 0.3-0.5% by weight of Mg, 0.01-0.5% by weight of Ca, and the remainder Al, wherein an oxide of the Mg and an oxide of Ca are each formed on an outer surface of the protective coating, wherein the alloy constituent is present in a layer that forms a finish of the protective coating relative to surroundings and that has a thickness of up to 200 nm, the method comprising:
heating the flat steel product to a heating temperature for hot forming, wherein the heating occurs under an ambient atmosphere or under an H 2 0-reduced atmosphere; and
hot forming the flat steel product to create the steel component.

12. The method of claim 11 wherein the oxides are formed during the hot forming of the flat steel product.

13. The method of claim 11 wherein a level of the heating temperature is such that at a start of forming the flat steel product has a hot forming temperature at which a microstructure of the steel substrate is austenitic, wherein the flat steel product is quenched after or during the hot forming so that a hardened microstructure forms in the microstructure of the steel substrate of the flat steel product.

14. The method of claim 13 wherein the heating temperature is at least 700° C.

15. The method of claim 11 wherein the protective coating include up to 20% by weight of other alloy elements.

Assignees

• Thyssenkrupp Steel Europe Ag
• Thyssenkrupp Ag

Inventors

• Banik Janko
• Etzold Ulrich
• Rössler Norbert
• Ruthenberg Manuela
• Wuttke Thiemo

Classifications

• C23C2/06

  Zinc or cadmium or alloys based thereon · CPC title

• Y10T428/12611

  Oxide-containing component · CPC title

• C22C38/22

  with molybdenum or tungsten · CPC title

• Y10T428/12597

  Noncrystalline silica or noncrystalline plural-oxide component [e.g., glass, etc.] · CPC title

• Y10T428/12618

  Plural oxides · CPC title