Hot stamped product, steel sheet for hot stamp, and manufacturing method thereof

Patent metadata

Field	Value
Publication number	US-11565299-B2
Application number	US-201816651659-A
Country	US
Kind code	B2
Filing date	Oct 2, 2018
Priority date	Oct 2, 2017
Publication date	Jan 31, 2023
Grant date	Jan 31, 2023

Abstract

The entirety or a part of this hot stamped product includes, as a chemical composition, by mass %, C: 0.001% or more and less than 0.080%, Si: 2.50% or less, Mn: 0.01% or more and less than 0.50%, P: 0.200% or less, S: 0.0200% or less, sol.Al: 0.001% to 2.500%, N: 0.0200% or less, Cr: 0.30% or more and less than 2.00%, and a remainder: Fe and impurities, in which a metallographic structure contains, by vol %, ferrite: more than 60.0%, martensite: 0% or more and less than 10.0%, and bainite: 0% or more and less than 20.0%, a tensile strength is less than 700 MPa, and ΔTS, which is a decrease in the tensile strength after a heat treatment at 170° C. for 20 minutes, is 100 MPa or less.

First claim

What is claimed is:

1. A hot stamped product, an entirety or a part of the hot stamped product comprising, as a chemical composition, by mass %:
C: 0.001% or more and less than 0.080%;
Si: 2.50% or less;
Mn: 0.01% or more and less than 0.50%;
P: 0.200% or less;
S: 0.0200% or less;
sol.Al: 0.001% to 2.500%;
N: 0.0200% or less;
Cr: 0.30% or more and less than 2.00%;
Ti: 0% to 0.300%;
Nb: 0% to 0.300%;
V: 0% to 0.300%;
Zr: 0% to 0.300%;
Mo: 0% to 2.00%;
Cu: 0% to 2.00%;
Ni: 0% to 2.00%;
B: 0% to 0.0200%;
Ca: 0% to 0.0100%;
Mg: 0% to 0.0100%;
REM: 0% to 0.1000%;
Bi: 0% to 0.0500%; and
a remainder: Fe and impurities,
wherein a metallographic structure contains, by vol %,
ferrite: more than 60.0%,
martensite: 0% or more and less than 10.0%, and
bainite: 0% or more and less than 20.0%,

a tensile strength is less than 700 MPa, and
ΔTS, which is a decrease in the tensile strength after a heat treatment at 170° C. for 20 minutes, is 100 MPa or less.

2. The hot stamped product according to claim 1 ,
wherein the chemical composition contains, by mass %, one or more selected from the group consisting of:
Ti: 0.001% to 0.300%;
Nb: 0.001% to 0.300%;
V: 0.001% to 0.300%;
Zr: 0.001% to 0.300%,
Mo: 0.001% to 2.00%;
Cu: 0.001% to 2.00%;
Ni: 0.001% to 2.00%;
B: 0.0001% to 0.0200%;
Ca: 0.0001% to 0.0100%;
Mg: 0,0001% to 0.0100%;
REM: 0.0001% to 0.1000%; and
Bi: 0.0001% to 0.0500%.

3. The hot stamped product according to claim 1 , further comprising:
a coating layer on a surface.

4. A steel sheet for hot stamp for use in manufacturing the hot stamped steel product according to claim 1 , comprising, as a chemical composition, by mass %:
C: 0.001% or more and less than 0.080%;
Si: 2.50% or less;
Mn: 0.01% or more and less than 0.50%;
P: 0.200% or less;
S: 0.0200% or less;
0.001 to 2.500%;
N: 0.0200% or less;
Cr: 0.30% or more and less than 2.00%;
Ti: 0% to 0.300%;
Nb: 0% to 0.300%;
V: 0% to 0.300%;
Zr: 0% to 0.300%;
Mo: 0% to 2.00%;
Cu: 0% to 2.00%;
Ni: 0% to 2.00%;
B: 0% to 0.0200%;
Ca: 0% to 0.0100%;
Mg: 0% to 0.0100%;
REM: 0% to 0.1000%;
Bi: 0% to 0.0500%; and
a remainder: Fe and impurities,
wherein a metallographic structure contains iron carbides, and a Mn content and a Cr content in the iron carbides satisfy Formula (i):
[Mn] θ +[Cr] θ >2.5  (i)

where meaning of each symbol in the formula is as follows:
[Mn] θ : the Mn content, in unit at %, in the iron carbides when a total amount of Fe, Mn, and Cr contained in the iron carbides is 100 at %; and
[Cr] θ : the Cr content, in unit at %, in the iron carbides when the total amount of Fe, Mn, and Cr contained in the iron carbides is 100 at %.

5. The steel sheet for hot stamp according to claim 4 ,
wherein the chemical composition contains, by mass %, one or more selected from the group consisting of:
Ti: 0.001% to 0.300%;
Nb: 0.001% to 0.300%;
V: 0.001% to 0.300%;
Zr: 0.001% to 0.300%;
Mo: 0.001% to 2.00%;
Cu: 0.001% to 2.00%;
Ni: 0.001% to 2.00%;
B: 0.0001% to 0.0200%;
Ca: 0.0001% to 0.0100%;
Mg: 0.0001% to 0.0100%;
REM: 0.0001% to 0.1000%; and
Bi: 0.0001% to 0.0500%.

6. The steel sheet for hot stamp according to claim 4 , further comprising:
a coating layer on a surface.

7. A manufacturing method of the hot stamped product according to claim 1 , the method comprising:
a heating process of heating a steel sheet for hot stamp comprising, as a chemical composition, by mass %:
C: 0.001% or more and less than 0.080%;
Si: 2.50% or less;
Mn: 0.01% or more and less than 0.50%;
P: 0.200% or less;
S: 0.0200% or less;
sol.Al: 0.001 to 2.500%;
N: 0.0200% or less;
Cr: 0.30% or more and less than 200%;
Ti: 0% to 0.300%;
Nb: 0% to 0.300%;
V: 0% to 0.300%;
Zr: 0% to 0.300%;
Mo: 0% to 2.00%;
Cu: 0% to 2.00%;
Ni: 0% to 2.00%;
B: 0% to 0.0200%;
Ca: 0% to 0.0100%;
Mg: 0% to 0.0100%;
REM: 0% to 0.1000%;
Bi: 0% to 0.0500%; and
a remainder: Fe and impurities,
wherein a metallographic structure contains iron carbides, and a Mn content and a Cr content in the iron carbides satisfy Formula (i):
[Mn] θ +[Cr] θ >2.5  (i)

where meaning of each symbol in the formula is as follows:
[Mn] θ : the Mn content, in unit at %, in the iron carbides when a total amount of Fe, Mn, and Cr contained in the iron carbides is 100 at %; and
[Cr] θ : the Cr content, in unit at %, in the iron carbides when the total amount of Fe, Mn, and Cr contained in the iron carbides is 100 at %,
to a heating temperature T° C.; and
a hot stamping process of performing hot stamping on the steel sheet for hot stamp after the heating process.

8. A manufacturing method of the hot stamped product according to claim 1 , the method comprising:
a joining process of joining a steel sheet for hot stamp comprising, as a chemical composition, by mass %:
C: 0.001% or more and less than 0.080%;
Si: 2.50% or less;
Mn: 0.01% or more and less than 0.50%;
P: 0.200% or less;
S: 0.0200% or less;
sol.Al: 0.001 to 2.500%;
N: 0.0200% or less;
Cr: 0.30% or more and less than 2.00%;
Ti: 0% to 0.300%;
Nb: 0% to 0.300%;
V: 0% to 0.300%;
Zr: 0% to 0.300%;
Mo: 0% to 2.00%;
Cu: 0% to 2.00%;
Ni: 0% to 2.00%;
B: 0% to 0.0200%;
Ca: 0% to 0.0100%;
Mg: 0% to 0.0100%;
REM: 0% to 0.1000%;
Bi: 0% to 0.0500%; and
a remainder: Fe and impurities,
wherein a metallographic structure contains iron carbides, and a Mn content and a Cr content in the iron carbides satisfy Formula (i):
[Mn] θ +[Cr] θ >2.5  (i)

where meaning of each symbol in the formula is as follows:
[Mn] θ : the Mn content, in unit at %, in the iron carbides when a total amount of Fe, Mn, and Cr contained in the iron carbides is 100 at %; and
[Cr] θ : the Cr content, in unit at %, in the iron carbides when the total amount of Fe, Mn, and Cr contained in the iron carbides is 100 at %,
to a steel sheet for joining to form a joined steel sheet;
a heating process of heating the joined steel sheet after the joining process to a heating temperature T° C.; and
a hot stamping process of performing hot stamping on the joined steel sheet after the heating process.

9. A manufacturing method of the hot stamped product according to claim 3 , the method comprising:
a heating process of heating a steel sheet for hot stamp comprising, as a chemical composition, by mass %:
C: 0.001% or more and less than 0.080%;
Si: 2.50% or less;
Mn: 0.01% or more and less than 0.50%;
P: 0.200% or less;
S: 0.0200% or less;
sol.Al: 0.001 to 2.500%;
N: 0.0200% or less;
Cr: 0.30% or more and less than 2.00%;
Ti: 0% to 0.300%;
Nb: 0% to 0.300%;
V: 0% to 0.300%;
Zr: 0% to 0.300%;
Mo: 0% to 2.00%;
Cu: 0% to 2.00%;
Ni: 0% to 2.00%;
B: 0% to 0.0200%;
Ca: 0% to 0.0100%;
Mg: 0% to 0.0100%;
REM: 0% to 0.1000%;
Bi: 0% to 0.0500%; and
a remainder: Fe and impurities,
wherein a metallographic structure contains iron carbides, and a Mn content and a Cr content in the iron carbides satisfy Formula (i):
[Mn] θ +[Cr] θ >2.5  (i)

where meaning of each symbol in the formula is as follows:
[Mn] θ : the Mn content, in unit at %, in the iron carbides when a total amount of Fe, Mn, and Cr contained in the iron carbides is 100 at %; and
[Cr] θ : the Cr content, in unit at %, in the iron carbides when the total amount of Mn, and Cr contained in the iron carbides is 100 at %, and
the steel sheet for hot stamp further comprising:
a coating layer on a surface,
to a heating temperature T° C.; and
a hot stamping process of performing hot stamping on the steel sheet after the heating process.

10. A manufacturing method of the hot stamped product according to cl

Assignees

• Nippon Steel Corp

Inventors

• Haga Jun
• Hikida Kazuo

Classifications

• C22C38/002

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

• C22C38/50

  with titanium or zirconium · CPC title

• C21D2211/008

  Martensite · CPC title

• C22C38/06

  containing aluminium · CPC title

• C22C38/04

  containing manganese · CPC title