Patent ID: 11866800
Assignee: NIPPON STEEL CORPORATION
Field: Materials, metallurgy (Chemistry)
Classification: CPC C  B  Y | IPC B  C

Claim 0:
1. A steel sheet comprising, as a composition, by mass %:
C: 0.0003% to 0.0100%;
Si: 0.005% to 1.500%;
Mn: 0.010% to 3.000%;
Al: 0.005% to 1.000%;
P: 0.100% or less;
S: 0.0200% or less;
N: 0.0150% or less;
O: 0.0100% or less;
V: 0% to 0.50%;
Cr: 0% to 1.00%;
Ni: 0% to 1.00%;
Cu: 0% to 1.00%;
Mo: 0% to 1.00%;
W: 0% to 1.00%;
B: 0% to 0.0100%;
Sn: 0% to 1.00%;
Sb: 0% to 0.20%;
one or two or more selected from the group of Ca, Ce, Mg, Zr, La, and REM: 0% to 0.0100% in total;
one or two selected from the group of Ti: 0.010% to 0.100% and Nb: 0.005% to 0.060%; and
a remainder including Fe and impurities,
wherein Expression (1) is satisfied,
a microstructure at a ¼ thickness position from a surface in a sheet thickness direction includes, by vol %, 95% or more ferrite, and 5% or less of a remainder of the microstructure, and the ferrite has a proportion of unrecrystallized ferrite of 5% or less, and
a half width w and an X-ray wavelength λ at a peak of (200) plane of the ferrite satisfy Expression (2),

0.80≤{(Ti/48−N/14)+Nb/93}/(C/12)≤5.00  (1),

w×λ≥0.20  (2),

wherein each of Ti, N, Nb, and C in Expression (1) represents a content by mass % of the element, and when the element is not included, 0 is substituted as the content of the element.