Hot stamping steel and producing method thereof

Patent metadata

Field	Value
Publication number	US-10308996-B2
Application number	US-201514935881-A
Country	US
Kind code	B2
Filing date	Nov 9, 2015
Priority date	Jul 30, 2015
Publication date	Jun 4, 2019
Grant date	Jun 4, 2019

Abstract

Disclosed is a steel composition for hot stamping that comprises carbon (C) in an amount of about 0.22 to about 0.25 wt %, silicon (Si) in an amount of about 0.2 to about 0.3 wt %, manganese (Mn) in an amount of about 1.2 to about 1.4 wt %, titanium (Ti) in an amount of about 0.02 to about 0.05 wt %, chromium (Cr) in an amount of about 0.11 to about 0.2 wt %, boron (B) in an amount of about 0.005 to about 0.01 wt %, zinc (Zr) in an amount of about 0.005 to about 0.02 wt %, niobium (Nb) in an amount of about 0.01 to about 0.05 wt %, tungsten (W) in an amount of about 0.1 to about 0.5 wt %, iron (Fe) constituting the remaining balance of the steel composition, all the wt % based on the total amount of the steel composition.

First claim

What is claimed is:

1. A steel composition for hot stamping, comprising:
carbon (C) in an amount of about 0.22 to about 0.25 wt %;
silicon (Si) in an amount of about 0.2 to about 0.3 wt %;
manganese (Mn) in an amount of about 1.2 to about 1.4 wt %;
titanium (Ti) in an amount of about 0.02 to about 0.05 wt %;
chromium (Cr) in an amount of about 0.11 to about 0.2 wt %;
boron (B) in an amount of about 0.005 to about 0.01 wt %;
zirconium (Zr) in an amount of about 0.005 to about 0.02 wt %;
niobium (Nb) in an amount of about 0.01 to about 0.05 wt %;
tungsten (W) in an amount of about 0.1 to about 0.5 wt %; and
iron (Fe) constituting the remaining balance of the steel composition,
wherein all the wt % based on the total amount of the steel composition.

2. The steel composition for hot stamping of claim 1 , consisting essentially of:
carbon (C) in an amount of about 0.22 to about 0.25 wt %;
silicon (Si) in an amount of about 0.2 to about 0.3 wt %;
manganese (Mn) in an amount of about 1.2 to about 1.4 wt %;
titanium (Ti) in an amount of about 0.02 to about 0.05 wt %;
chromium (Cr) in an amount of about 0.11 to about 0.2 wt %;
boron (B) in an amount of about 0.005 to about 0.01 wt %;
zirconium (Zr) in an amount of about 0.005 to about 0.02 wt %;
niobium (Nb) in an amount of about 0.01 to about 0.05 wt %;
tungsten (W) in an amount of about 0.1 to about 0.5 wt %; and
iron (Fe) constituting the remaining balance of the steel composition,
wherein all the wt % based on the total amount of the steel composition.

3. A hot stamping steel, comprising:
a parental metal comprising a steel composition of claim 1 ;
a Zn plating layer coated on the parental metal; and
a Zn—Fe alloy layer formed, by hot stamping, between the parental metal and the Zn plating layer.

4. The hot stamping steel of claim 3 , wherein the hot stamping steel has a tensile strength of about 1470 MPa or greater.

5. The hot stamping steel of claim 3 , wherein the Zn—Fe alloy layer has a Zn content of about 90% by weight or greater, based on the total weight of the Zn—Fe alloy layer.

6. A method for manufacturing a hot stamping steel, comprising steps of:
producing a steel plate comprising carbon (C) in an amount of about 0.22 to about 0.25 wt %, silicon (Si) in an amount of about 0.2 to about 0.3 wt %, manganese (Mn) in an amount of about 1.2 to about 1.4 wt %, titanium (Ti) in an amount of about 0.02 to about 0.05 wt %, chromium (Cr) in an amount of about 0.11 to about 0.2 wt %, boron (B) in an amount of about 0.005 to about 0.01 wt %, zirconium (Zr) in an amount of about 0.005 to about 0.02 wt %, niobium (Nb) in an amount of about 0.01 to about 0.05 wt %, tungsten (W) in an amount of about 0.1 to about 0.5 wt %, iron (Fe) constituting the remaining balance of the steel composition, all the wt % based on the total amount of the steel composition;
plating the steel plate with zinc (Zn);
austenitizing the steel plate;
hot stamping the Zn-plated steel plate at a temperature of about 750 to 850° C.; and
inducing martensitic transformation in the steel plate.

7. The method of claim 6 , wherein the austenitizing step is performed by heating the steel plate to a temperature of about 900° C. or greater.

8. The method of claim 7 , further comprising steps of:
cooling the heated steel plate at a cooling rate of about 600° C./min or greater to a temperature of about 750 to 850° C. between the austenitizing step and the hot stamping step.

9. The method of claim 6 , wherein the martensitic transformation is achieved by quenching the steel plate at a rate of about 3000° C./min.

Assignees

• Hyundai Motor Co Ltd

Inventors

• Bae Moon Ki
• Hong Seung Hyun
• Cha Sung Chul

Classifications

• C21D8/02

  during manufacturing of plates or strips (C21D8/12 takes precedence) · CPC title

• Y10T428/12958

  Next to Fe-base component · CPC title

• C22C38/50

  with titanium or zirconium · CPC title

• C22C38/04 Primary

  containing manganese · CPC title

• C22C38/18

  containing chromium · CPC title