Patent ID: 11959157
Assignee: JFE STEEL CORPORATION
Field: Materials, metallurgy (Chemistry)
Classification: CPC C | IPC C

Claim 0:
1. A high-Mn steel comprising:
a chemical composition consisting of, in mass %,
C: 0.100% or more and 0.700% or less,
Si: 0.05% or more and 1.00% or less,
Mn: 20.0% or more and 35.0% or less,
P: 0.030% or less,
S: 0.0070% or less,
Al: 0.010% or more and 0.070% or less,
Cr: 0.50% or more and 5.00% or less,
N: 0.0050% or more and 0.0500% or less,
O: 0.0050% or less,
Ti: 0.005% or less,
Nb: 0.005% or less, and
optionally at least one group selected from the following (A) to (B);
(A) one or more selected from
Cu: 0.01% or more and 0.50% or less,
Mo: 2.00% or less,
V: 2.00% or less, and
W: 2.00% or less;

(B) one or more selected from
Ca: 0.0005% or more and 0.0050% or less,
Mg: 0.0005% or more and 0.0050% or less, and
REM: 0.0010% or more and 0.0200% or less,

with a balance consisting of Fe and inevitable impurities; and
a microstructure having austenite as a matrix,
wherein in the microstructure, a Mn concentration of a Mn-concentrated portion is 38.0% or less, and an average of Kernel Average Misorientation value is 0.3 or more,
yield stress is 400 MPa or more,
absorbed energy vE−196 in a Charpy impact test at −196° C. is 100 J or more, and
percent brittle fracture is less than 10%, and
wherein the high Mn steel has a surface roughness Ra of 200 μm or less.