Granted Patent B2

US 12,410,498 · App. 17/781,239 · Granted Sep 9, 2025

Inventors: Yuri Toda (Tokyo, JP); Kodai Murasawa (Tokyo, JP); Daisuke Maeda (Tokyo, JP); Kazuo Hikida (Tokyo, JP)

Assignee: NIPPON STEEL CORPORATION

C22C38/60B21D22/022C21D6/005C21D6/008C21D8/0205C21D8/0226C21D8/0236C21D9/48C22C38/001C22C38/002C22C38/005C22C38/02C22C38/04C22C38/06C22C38/105C22C38/12C22C38/14C22C38/16C22C38/30C22C38/34C22C38/38C21D2211/001C21D2211/002C21D2211/008

Abstract

Claims (41)

1. A hot-stamping formed body comprising, as a chemical composition, by mass %:

C: more than 0.50% and 1.00% or less;

Si: 0.50% to 3.00%;

Mn: more than 3.00% and 5.00% or less;

Al: 0.100% to 3.000%;

Co: 0.100% to 3.000%;

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%;

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 in a range of 20% to 30%, bainite and tempered martensite of which a total area ratio is in a range of 70% to 80%, and a remainder in microstructure of which an area ratio is less than 5%,

wherein within a region which has a length of 50 μm and is present between a depth corresponding to ⅛ of a thickness from the surface and a depth corresponding to ⅜ of a thickness from the surface 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 <011> direction to a total length of a grain boundary having a rotation angle in a range of 4° to 12° to a <011> direction, a grain boundary having a rotation angle in a range of 49° to 54° to a <011> direction, and a grain boundary having a rotation angle in the range of 55° to 75° to the <011> direction is 30% 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%;

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%.

Assignments (1)

Priority Claims (1)

Continuity (1)

References Cited (24)