Controlling Liquid Metal Embrittlement In Galvanized Press-Hardened Components

Patent metadata

Field	Value
Publication number	US-2016145731-A1
Application number	US-201514627579-A
Country	US
Kind code	A1
Filing date	Feb 20, 2015
Priority date	Nov 26, 2014
Publication date	May 26, 2016
Grant date	—

Abstract

Methods for press hardening galvanized, pre-treated, optionally non-annealed steel alloys are provided. The press-hardened steel alloy may have an ultimate tensile strength (UTS) of at least about 1,000 MPa and is substantially free of liquid metal embrittlement (LME). The press-hardened steel alloy may be further quenched to below room temperature. The press-hardened steel may have a multi-phase microstructure of ferrite at greater than or equal to about 1% to less than or equal to about 60% by volume and a combined volume percentage of martensite, retained austenite, and other transformation products at greater than or equal to about 40% to less than or equal to about 99%.

First claim

What is claimed is:

1 . A method of press-hardening a galvanized steel alloy comprising:
creating a blank from a pre-treated, galvanized steel alloy; heating the blank to a temperature of less than or equal to about 782° C. to partially austenitize the galvanized steel alloy; and press hardening the blank of the galvanized steel alloy to form a press-hardened component having an ultimate tensile strength of greater than or equal to about 1,000 MPa to less than or equal to about 2,000 MPa that is substantially free of liquid metal embrittlement.

2 . The method of claim 1 , wherein the steel alloy comprises carbon at greater than or equal to about 0.1 weight % to less than or equal to about 0.6 weight % and manganese at greater than 0 weight % to less than or equal to about 6 weight %.

3 . The method of claim 1 , wherein the steel alloy comprises:
manganese at greater than or equal to about 1 weight % to less than or equal to about 2 weight %; carbon at greater than or equal to about 0.3 weight % to less than or equal to about 0.5 weight %; or manganese at greater than or equal to about 1 weight % to less than or equal to about 2 weight % and carbon at greater than or equal to about 0.3 weight % to less than or equal to about 0.5 weight %.

4 . The method of claim 1 , wherein the steel alloy comprises silicon at greater than 0 weight % to less than or equal to about 1 weight %.

5 . The method of claim 1 , wherein the heating occurs at a temperature of greater than or equal to about 725° C. to less than or equal to about 782° C.

6 . The method of claim 1 , further comprising quenching the press-hardened component to below room temperature after the press hardening.

7 . The method of claim 1 , wherein the press-hardened component has a multi-phase microstructure comprising ferrite at greater than or equal to about 1% to less than or equal to about 60% by volume and a combined volume percentage of martensite, retained austenite, and other transformation products at greater than or equal to about 40% to less than or equal to about 99%.

8 . A method of press-hardening a galvanized steel alloy comprising:
creating a blank from a pre-treated, galvanized steel alloy; heating the blank to a temperature of less than or equal to about 782° C. to partially austenitize the galvanized steel alloy; and press hardening the blank of the galvanized steel alloy to form a press-hardened component having a microstructure that comprises ferrite at greater than or equal to about 1% to less than or equal to about 60% by volume and a combined volume percentage of martensite, retained austenite, and other transformation products at greater than or equal to about 40% to less than or equal to about 99%.

9 . The method of claim 8 , wherein the steel alloy comprises carbon at greater than or equal to about 0.1 weight % to less than or equal to about 0.6 weight % and manganese at greater than 0 weight % to less than or equal to about 6 weight %.

10 . The method of claim 8 , wherein the steel alloy comprises:
manganese at greater than or equal to about 1 weight % to less than or equal to about 2 weight %; carbon at greater than or equal to about 0.3 weight % to less than or equal to about 0.5 weight %; or manganese at greater than or equal to about 1 weight % to less than or equal to about 2 weight % and carbon at greater than or equal to about 0.3 weight % to less than or equal to about 0.5 weight %.

11 . The method of claim 8 , wherein the steel alloy comprises silicon at greater than 0 weight % to less than or equal to about 1 weight %.

12 . The method of claim 8 , wherein the press-hardened component has an ultimate tensile strength of greater than or equal to about 1,000 MPa to less than or equal to about 2,000 MPa.

13 . The method of claim 8 , wherein the heating occurs at a temperature of greater than or equal to about 725° C. to less than or equal to about 782° C.

14 . The method of claim 8 , further comprising quenching the press-hardened component to below room temperature after the press hardening.

15 . A method of press-hardening a galvanized steel alloy comprising:
creating a blank from a cold-rolled, non-annealed, hot-dipped galvanized steel alloy; heating the blank to a temperature of less than or equal to about 782° C. to partially austenitize the galvanized steel alloy; and press-hardening the blank of the galvanized steel alloy to form a press-hardened component having a microstructure that comprises ferrite at greater than or equal to about 1% to less than or equal to about 60% by volume and a combined volume percentage of martensite, retained austenite, and other transformation products at greater than or equal to about 40% to less than or equal to about 99%.

16 . The method of claim 15 , wherein the steel alloy comprises:
manganese at greater than or equal to about 1 weight % to less than or equal to about 2 weight %; carbon at greater than or equal to about 0.3 weight % to less than or equal to about 0.5 weight %; silicon at greater than 0 weight % to less than or equal to about 1 weight %; or manganese at greater than or equal to about 1 weight % to less than or equal to about 2 weight %, carbon at greater than or equal to about 0.3 weight % to less than or equal to about 0.5 weight %, and silicon at greater than 0 weight % to less than or equal to about 1 weight %.

17 . The method of claim 15 , wherein the press-hardened component has an ultimate tensile strength of greater than or equal to about 1,000 MPa to less than or equal to about 2,000 MPa.

18 . The method of claim 15 , wherein the heating occurs at a temperature of greater than or equal to about 725° C. to less than or equal to about 782° C.

19 . The method of claim 15 , further comprising quenching the press-hardened component to below room temperature after the press hardening.

20 . The method of claim 15 , consisting essentially of uncoiling a cold-rolled non-annealed coil comprising a steel alloy and hot-dip galvanizing the cold-rolled non-annealed steel alloy to form a cold-rolled, non-annealed hot-dipped galvanized steel alloy, coiling the cold-rolled, non-annealed hot-dipped galvanized steel alloy, and uncoiling and creating a blank from the cold-rolled, non-annealed hot-dipped galvanized steel alloy before the heating.

21 . The method of claim 15 , consisting essentially of uncoiling a cold-rolled non-annealed coil comprising a steel alloy and hot-dip galvanizing the cold-rolled non-annealed steel alloy in a zinc galvanization bath to form a cold-rolled, non-annealed hot-dipped galvanized steel alloy, coiling the cold-rolled, non-annealed hot-dipped galvanized steel alloy, uncoiling and creating a blank from the cold-rolled, non-annealed hot-dipped galvanized steel alloy before the heating, and quenching the press-hardened component after the press hardening step.

Assignees

• Gm Global Tech Operations Inc

Inventors

• Sachdev Anil K
• Brown Tyson W

Classifications

• C21D8/00 Primary

  Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment (hardening articles or materials formed by forging or rolling with no further heating beyond that required for the formation C21D1/02) · CPC title

• C21D2211/005

  Ferrite · CPC title

• C21D6/008

  containing Si · CPC title

• C21D6/005

  containing Mn · CPC title

• C22C38/02

  containing silicon · CPC title