Hot-rolled steel sheet

Patent metadata

Field	Value
Publication number	US-12435382-B2
Application number	US-202017792985-A
Country	US
Kind code	B2
Filing date	Dec 11, 2020
Priority date	Jan 27, 2020
Publication date	Oct 7, 2025
Grant date	Oct 7, 2025

Abstract

This hot-rolled steel sheet has a predetermined chemical composition, in which a metallographic structure contains, by area %, less than 3.0% of residual austenite, 15.0% or more and less than 60.0% of ferrite, and less than 5.0% of pearlite, has a ratio L 60 /L 7 of a length L 60 of a grain boundary having a crystal misorientation of 60° to a length L 7 of a grain boundary having a crystal misorientation of 7° about a < 110 > direction of 0.60 or more, has a standard deviation of a Mn concentration of 0.60 mass % or less, and has a tensile strength of 980 MPa or more.

First claim

The invention claimed is:

1. A hot-rolled steel sheet comprising, as a chemical composition, by mass %:
C: 0.050% to 0.250%;
Si: 0.05% to 3.00%;
Mn: 1.00% to 4.00%;
one or more of Ti, Nb, or V: 0.060% to 0.500% in total;
sol. Al: 0.001% to 2.000%;
P: 0.100% or less;
S: 0.0300% or less;
N: 0.1000% or less;
O: 0.0100% or less;
Cu: 0% to 2.00%;
Cr: 0% to 2.00%;
Mo: 0% to 1.00%;
Ni: 0% to 2.00%;
B: 0% to 0.0100%;
Ca: 0% to 0.0200%;
Mg: 0% to 0.0200%;
REM: 0% to 0.1000%;
Bi: 0% to 0.020%;
one or more of Zr, Co, Zn, or W: 0% to 1.00% in total;
Sn: 0% to 0.050%; and
a remainder comprising Fe and impurities,
wherein the metallographic structure
contains, by area %, less than 3.0% of residual austenite, 15.0% or more and less than 60.0% of ferrite, and less than 5.0% of pearlite,
has a ratio L 60 /L 7 of a length L 60 of a grain boundary having a crystal misorientation of 60° to a length L 7 of a grain boundary having a crystal misorientation of 7° about a < 110 > direction of 0.60 or more,
has a standard deviation of a Mn concentration of 0.60 mass % or less, and has a tensile strength of 980 MPa or more.

2. The hot-rolled steel sheet according to claim 1 ,
wherein an average grain size of a surface layer is less than 3.0 μm.

3. The hot-rolled steel sheet according to claim 1 ,
wherein the hot-rolled steel sheet includes, as the chemical composition, by mass %, one or two or more selected from the group of
Cu: 0.01% to 2.00%,
Cr: 0.01% to 2.00%,
Mo: 0.01% to 1.00%,
Ni: 0.02% to 2.00%,
B: 0.0001% to 0.0100%,
Ca: 0.0005% to 0.0200%,
Mg: 0.0005% to 0.0200%,
REM: 0.0005% to 0.1000%, and
Bi: 0.0005% to 0.020%.

4. The hot-rolled steel sheet according to claim 2 ,
wherein the hot-rolled steel sheet includes, as the chemical composition, by mass %, one or two or more selected from the group of
Cu: 0.01% to 2.00%,
Cr: 0.01% to 2.00%,
Mo: 0.01% to 1.00%,
Ni: 0.02% to 2.00%,
B: 0.0001% to 0.0100%,
Ca: 0.0005% to 0.0200%,
Mg: 0.0005% to 0.0200%,
REM: 0.0005% to 0.1000%, and
Bi: 0.0005% to 0.020%.

Assignees

• Nippon Steel Corp

Inventors

• Shuto Hiroshi
• Tsutsui Kazumasa
• Ando Jun
• Hayashi Koutarou
• Sakakibara Akifumi
• Kobayashi Shunsuke

Classifications

• C22C38/06

  containing aluminium · CPC title

• C22C38/04

  containing manganese · CPC title

• C22C38/02

  containing silicon · CPC title

• C22C38/002

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

• C22C38/001 Primary

  containing N · CPC title