Hot-stamping formed body
A hot-stamping formed body has a predetermined chemical composition and includes microstructure which includes residual austenite of which an area ratio is 5% or more and less than 10%. Among grain boundaries of crystal grains of bainite and tempered martensite in the microstructure, a ratio of a length of a grain boundary having a rotation angle in a range of 55° to 75° to a total length of a grain boundary having a rotation angle in a range of 4° to 12°, a grain boundary having a rotation angle in a range of 49° to 54°, and a grain boundary having a rotation angle in a range of 55° to 75° to the <011> direction as a rotation axis is 30% or more. The tensile strength of the hot-stamping formed body is 1500 MPa or more.
1. A hot-stamping formed body comprising, as a chemical composition, by mass %:
C: 0.30% to 0.50%;
Si: 0.50% to 3.00%;
Mn: 0.50% to 3.00%;
Al: 0.0002% to 2.000%;
P: 0.100% or less;
S: 0.1000% or less;
N: 0.0100% or less;
Nb: 0% to 0.150%;
Ti: 0% to 0.150%;
Co: 0% to 2.00%;
Mo: 0% to 1.00%;
Cr: 0% to 1.00%;
Cu: 0% to 1.00%;
V: 0% to 1.00%;
W: 0% to 1.00%;
Ni: 0% to 3.00%;
Mg: 0% to 1.00%;
Zr: 0% to 1.00%;
Sb: 0% to 1.00%;
Ca: 0% to 0.10%;
REM: 0% to 0.30%;
B: 0% to 0.0100%; and
a remainder consisting of Fe and impurities; and
microstructure which includes residual austenite of which an area ratio is 5% or more and less than 10%, bainite and tempered martensite of which a total area ratio exceeds 90% and is 95% or less, and a remainder in microstructure of which an area ratio is less than 5%,
among grain boundaries of crystal grains of the bainite and the tempered martensite, a ratio of a length of a grain boundary having a rotation angle in a range of 55° to 75° to a total length of a grain boundary having a rotation angle in a range of 4° to 12°, a grain boundary having a rotation angle in a range of 49° to 54°, and the grain boundary having a rotation angle in a range of 55° to 75° to the <011> direction as a rotation axis is 30% or more,
wherein a tensile strength of the hot-stamping formed body is 1500 MPa or more.
2. The hot-stamping formed body according to claim 1 , further comprising, as the chemical composition, by mass %, at least one selected from the group of:
Nb: 0.010% to 0.150%;
Ti: 0.010% to 0.150%;
Co: 0.01% to 2.00%;
Mo: 0.005% to 1.00%;
Cr: 0.005% to 1.00%;
Cu: 0.001% to 1.00%;
V: 0.0005% to 1.00%;
W: 0.001% to 1.00%;
Ni: 0.001% to 3.00%;
Mg: 0.001% to 1.00%;
Zr: 0.001% to 1.00%;
Sb: 0.001% to 1.00%;
Ca: 0.001% to 0.10%;
REM: 0.001% to 0.30%; and
B: 0.0005% to 0.0100%.
3. A hot-stamping formed body comprising, as a chemical composition, by mass %:
C: 0.30% to 0.50%;
Si: 0.50% to 3.00%;
Mn: 0.50% to 3.00%;
Al: 0.0002% to 2.000%;
P: 0.100% or less;
S: 0.1000% or less;
N: 0.0100% or less;
Nb: 0% to 0.150%;
Ti: 0% to 0.150%;
Co: 0% to 2.00%;
Mo: 0% to 1.00%;
Cr: 0% to 1.00%;
Cu: 0% to 1.00%;
V: 0% to 1.00%;
W: 0% to 1.00%;
Ni: 0% to 3.00%;
Mg: 0% to 1.00%;
Zr: 0% to 1.00%;
Sb: 0% to 1.00%;
Ca: 0% to 0.10%;
REM: 0% to 0.30%;
B: 0% to 0.0100%; and
a remainder comprising Fe and impurities; and
microstructure which includes residual austenite of which an area ratio is 5% or more and less than 10%, bainite and tempered martensite of which a total area ratio exceeds 90% and is 95% or less, and a remainder in microstructure of which an area ratio is less than 5%,
among grain boundaries of crystal grains of the bainite and the tempered martensite, a ratio of a length of a grain boundary having a rotation angle in a range of 55° to 75° to a total length of a grain boundary having a rotation angle in a range of 4° to 12°, a grain boundary having a rotation angle in a range of 49° to 54°, and the grain boundary having a rotation angle in a range of 55° to 75° to the <011> direction as a rotation axis is 30% or more,
wherein a tensile strength of the hot-stamping formed body is 1500 MPa or more.