Automotive component with enhanced strength

Patent metadata

Field	Value
Publication number	US-11761069-B2
Application number	US-202017093801-A
Country	US
Kind code	B2
Filing date	Nov 10, 2020
Priority date	Nov 11, 2019
Publication date	Sep 19, 2023
Grant date	Sep 19, 2023

Abstract

An automotive component is produced by hot forming and press hardening a hardenable steel alloy having a tensile strength of at least 1700 MPa. The hardenable steel alloy, in addition to a balance made up of iron and melting-related impurities, has the following alloy elements carbon, niobium, and titanium. The automotive component is coated by a thermal coating process.

First claim

The invention claimed is:

1. A hot formed and press hardened automotive component, comprising:
a steel alloy having a tensile strength of at least 1700 MPa; and
first and second skin-decarburized layers,
wherein the steel alloy comprises a composition of the following alloy elements expressed in percent by weight, in addition to a balance of iron and impurities:
carbon (C): 0.33-0.37,
niobium (Nb): 0.02-0.06,
titanium (Ti): 0.005-0.02,

the automotive component has a thermal coating layer coated by a thermal coating process at a temperature of 150° C. to 450° C.,
the first skin-decarburized layer is disposed at a first surface of the automotive component,
the second skin-decarburized layer is disposed at a second surface of the automotive component,
a carbon content in the skin-decarburized layers is at least 20% lower than in a middle stratum of the automotive component, and
the middle stratum is disposed between the skin-decarburized layers.

2. The automotive component according to claim 1 , wherein the automotive component has a tensile strength Rm of greater than 1800 MPa.

3. The automotive component according to claim 1 , wherein the automotive component is a bumper support.

4. The automotive component according to claim 1 , wherein a total of a titanium content and a niobium content of the titanium and the niobium alloy elements is between 0.02 and 0.08 wt %, wherein the titanium content is greater than the niobium content by 0.01 wt %.

5. The automotive component according to claim 1 , wherein the thermal coating process is implemented as a cathodic e-coat coating process at a temperature between 150° C. and 250° C. in a time of 1 to 30 minutes.

6. The automotive component according to claim 1 , wherein at least one of the further alloy elements listed below is contained in the steel alloy, expressed in percent by weight:

silicon (Si)
0.15-0.35

manganese (Mn)
1.1-1.5

phosphorus (P)
max. 0.025

sulfur (S)
max. 0.005

aluminum (Al)
0.01-0.08

boron (B)
0.001-0.003

chromium (Cr)
0.08-0.35

Cr + Mo
 0.08-0.35.

7. The automotive component according to claim 5 , wherein the automotive component has a yield strength RP0.2 of 1350-1600 MPa after the cathodic e-coat coating.

8. The automotive component according to claim 1 , wherein the skin-decarburized layers have a layer thickness of 5 to 70 μm.

9. The automotive component according to claim 1 , wherein the automotive component has a tensile strength Rm of greater than 1850 MPa.

10. The automotive component according to claim 1 , wherein the automotive component is a bumper arrangement with crash boxes comprising a weld-assembled component.

11. The automotive component according to claim 1 , wherein the thermal coating process is implemented as a cathodic e-coat coating process at a temperature of between 150° C. and 250° C. in a time of 10 to 30 minutes.

12. The automotive component according to claim 1 , wherein the skin-decarburized layers are disposed below the thermal coating layer.

13. The automotive component according to claim 1 , wherein the skin-decarburized layers have a layer thickness of 10 to 40 μm.

14. The automotive component according to claim 1 , wherein the steel alloy comprises the following element expressed in percent by weight: carbon (C): 0.33-0.35.

15. The automotive component according to claim 1 , wherein the steel alloy comprises the following element expressed in percent by weight: niobium (Nb): 0.03-0.05.

16. The automotive component according to claim 1 , wherein the steel alloy comprises the following element expressed in percent by weight: titanium (Ti): 0.005-0.015.

17. The automotive component according to claim 1 , wherein the steel alloy comprises the following element expressed in percent by weight: titanium (Ti): 0.005-0.01.

18. A method of forming an automotive component, the method comprising:
hot forming and press hardening a hardenable steel alloy to a tensile strength of at least 1700 MPa to obtain the automotive component, the automotive component further comprising first and second skin-decarburized layers,
wherein the hardenable steel alloy comprises a composition of the following alloy elements expressed in percent by weight, in addition to a balance of iron and impurities:
carbon (C): 0.33-0.37,
niobium (Nb): 0.02-0.06,
titanium (Ti): 0.005-0.02; and

coating the automotive component with a thermal coating layer by a thermal coating process at a temperature of 150° C. to 450° C., wherein
the first skin-decarburized layer is disposed at a first surface of the automotive component,
the second skin-decarburized layer is disposed at a second surface of the automotive component,
a carbon content in the skin-decarburized layers is at least 20% lower than in a middle stratum of the automotive component, and
the middle stratum is disposed between the skin-decarburized layers.

Assignees

• Benteler Automobiltechnik Gmbh

Inventors

• Frost Georg
• Frehn Andreas
• Bake Karsten
• Holzweissig Martin
• Lapsien Rainer

Classifications

• C22C38/12 Primary

  containing tungsten, tantalum, molybdenum, vanadium, or niobium · CPC title

• C22C38/002 Primary

  containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60 · CPC title

• C22C38/38 Primary

  with more than 1.5% by weight of manganese · CPC title

• C22C38/14

  containing titanium or zirconium · CPC title

• C22C38/06

  containing aluminium · CPC title