Hot stamped high strength part excellent in post painting anticorrosion property and method of production of same

• US 8,986,849 B2
• Filed: 03/30/2012
• Issued: 03/24/2015
• Est. Priority Date: 04/01/2011
• Status: Active Grant

• Current Assignee: Nippon Steel Corporation
• Original Assignee: Nippon Steel & Sumitomo Metal Corporation (Nippon Steel Corporation)
• Inventors: Maki, Jun, Kusumi, Kazuhisa, Abe, Masayuki, Kurosaki, Masao
• Primary Examiner(s): Blackwell, Gwendolyn
• Assistant Examiner(s): DUMBRIS, SETH M
• Application Number:
  US14/008,854
• Publication Number:
  US 20140030544A1
• Time in Patent Office: 1,089 Days
• Field of Search: None
• US Class Current: 428/653
• CPC Class Codes: B21B 1/26 by hot-rolling , e.g. Steckel hot mill
• CPC Class Codes: C21D 1/673 for die quenching
• CPC Class Codes: C21D 2211/004 Dispersions; Precipitations
• CPC Class Codes: C21D 7/13 by hot working
• CPC Class Codes: C21D 8/0226 Hot rolling
• CPC Class Codes: C21D 8/0236 Cold rolling
• CPC Class Codes: C21D 8/0263 following hot rolling
• CPC Class Codes: C21D 9/46 for sheet metals
• CPC Class Codes: C22C 38/001 containing N
• CPC Class Codes: C22C 38/02 containing silicon
• CPC Class Codes: C22C 38/04 containing manganese
• CPC Class Codes: C22C 38/06 containing aluminium
• CPC Class Codes: C22C 38/14 containing titanium or zirconium
• CPC Class Codes: C22C 38/20 with copper
• CPC Class Codes: C22C 38/22 with molybdenum or tungsten
• CPC Class Codes: C22C 38/28 with titanium or zirconium
• CPC Class Codes: C22C 38/32 with boron
• CPC Class Codes: C22C 38/38 with more than 1.5% by weight of manganese
• CPC Class Codes: C22C 38/44 with molybdenum or tungsten
• CPC Class Codes: C22C 38/50 with titanium or zirconium
• CPC Class Codes: C22C 38/54 : with boron
• CPC Class Codes: C22C 38/60 : containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
• CPC Class Codes: C23C 2/0038 : characterised by the pre-treatment chambers located immediately upstream of the bath or occurring locally before the dipping process
• CPC Class Codes: C23C 2/02 : Pretreatment of the material to be coated, e.g. for coating on selected surface areas C23C2/30 takes precedence
• CPC Class Codes: C23C 2/0222 : in a reactive atmosphere, e.g. oxidising or reducing atmosphere C23C2/024 takes precedence
• CPC Class Codes: C23C 2/12 : Aluminium or alloys based thereon
• CPC Class Codes: C23C 2/26 : After-treatment C23C2/14 takes precedence
• CPC Class Codes: C23C 2/28 : Thermal after-treatment, e.g. treatment in oil bath
• CPC Class Codes: C23C 2/29 : Cooling or quenching
• CPC Class Codes: C23C 2/34 : characterised by the shape of the material to be treated C23C2/14 takes precedence
• CPC Class Codes: Y10T 428/12611 : Oxide-containing component
• CPC Class Codes: Y10T 428/12757 : Fe
• CPC Class Codes: Y10T 428/12951 : Fe-base component
• CPC Class Codes: Y10T 428/12972 : Containing 0.01-1.7% carbon [i.e., steel]
• CPC Class Codes: Y10T 428/31678 : Of metal

Abstract

A hot stamped high strength part which is excellent in post painting anticorrosion property, which hot stamped high strength part has an alloy plating layer including an Al—Fe intermetallic compound phase on the surface of the steel sheet. The alloy plating layer is comprised from phases of a plurality of intermetallic compounds, a mean linear intercept length of crystal grains of a phase containing Al: 40 to 65 mass % among the phases of the plurality of intermetallic compounds is 3 to 20 μm, an average value of thickness of the Al—Fe alloy plating layer is 10 to 50 μm, and a ratio of the average value of thickness to the standard deviation of thickness of the Al—Fe alloy plating layer satisfies the following relationship: 0<standard deviation of thickness/average value of thickness≦0.15.

Claims

1. A hot stamped high strength part formed of a steel sheet which is excellent in post painting anticorrosion property, comprising an alloy plating layer comprising an Al—

Fe intermetallic compound phase on the surface of the steel sheet,

said alloy plating layer is comprised from phases of a plurality of intermetallic compounds,

a mean linear intercept length of crystal grains of a phase containing Al;

40 to 65 mass % among said phases of the plurality of intermetallic compounds is 3 to 20 μ

m,

an average value of thickness of said Al—

Fe alloy plating layer is 10 to 50 μ

m, and

a ratio of the average value of thickness to the standard deviation of thickness of said Al—

Fe alloy plating layer satisfies the following relationship;

0<

standard deviation of thickness/average value of thickness≦

0.15.

2. The hot stamped high strength part which is excellent in post painting anticorrosion property as set forth in claim 1 characterized in that said ratio of the average value of thickness to the standard deviation of thickness is 0.1 or less.

3. The hot stamped high strength part which is excellent in post painting anticorrosion property as set forth in claim 1 or 2 characterized in that said Al—

Fe alloy plating layer contains, by mass %, Si;

2 to 7%.

4. The hot stamped high strength part which is excellent in post painting anticorrosion property as set forth in claim 1 or 2 characterized in that a surface film layer which contains ZnO is laid on the surface of said Al—

Fe alloy plating layer.

5. The hot stamped high strength part which is excellent in post painting anticorrosion property as set forth in claim 4 characterized in that a content of ZnO of said surface film layer is, converted to mass of Zn, 0.3 to 7 g/m² per side.

6. The hot stamped high strength part which is excellent in post painting anticorrosion property as set forth in claim 1 or 2 characterized in that said steel sheet is comprised of a steel sheet of chemical ingredients which comprise as ingredients, by mass %,

C:

0.1 to 0.5%,

Si;

0.01 to 0.7%,

Mn;

0.2 to 2.5%,

Al;

0.01 to 0.5%,

P;

0.001 to 0.1%,

S;

0.001 to 0.1%,

N;

0.0010% to 0.05%, and

a balance of Fe and unavoidable impurities.

7. The hot stamped high strength part which is excellent in post painting anticorrosion property as set forth in claim 6 characterized in that said steel sheet further comprises, by mass %, one or more elements selected from

Cr:

over 0.4 to 3%,

Mo;

0.005 to 0.5%,

B;

0.0001 to 0.01%,

W;

0.01 to 3%,

V;

0.01 to 2%,

Ti;

0.005 to 0.5%,

Nb;

0.01 to 1%

Ni;

0.01 to 5%,

Cu;

0.1 to 3%,

Sn;

0.005% to 0.1%, and

Sb;

0.005% to 0.1%.