Hot-rolled steel sheet, cold-rolled steel sheet, galvanized steel sheet, and methods of manufacturing the same
A hot-rolled steel sheet has an average value of the X-ray random intensity ratio of a {100} <011> to {223} <110> orientation group at least in a sheet thickness central portion that is in a sheet thickness range of ⅝ to ⅜ from a steel sheet surface of 1.0 to 6.0, an X-ray random intensity ratio of a {332} <113> crystal orientation of 1.0 to 5.0, rC which is an r value in a direction perpendicular to a rolling direction of 0.70 to 1.10, and r30 which is an r value in a direction that forms an angle of 30° with respect to the rolling direction of 0.70 to 1.10.
1. A hot-rolled steel sheet comprising, by mass %:
C: 0.0001% to 0.40%;
Si: 0.001% to 2.5%;
Mn: 0.001% to 4.0%;
P: 0.001% to 0.15%;
S: 0.0005% to 0.03%;
Al: 0.001% to 2.0%;
N: 0.0005% to 0.01%;
O: 0.0005% to 0.01%;
and further comprising one or two or more of:
Ti: 0.001% to 0.20%;
Nb: 0.001% to 0.20%;
V: 0.001% to 1.0%;
W: 0.001% to 1.0%;
B: 0.0001% to 0.0050%;
Mo: 0.001% to 1.0%;
Cr: 0.001% to 2.0%;
Cu: 0.001% to 2.0%;
Ni: 0.001% to 2.0%;
Co: 0.0001% to 1.0%;
Sn: 0.0001% to 0.2%;
Zr: 0.0001% to 0.2%;
As: 0.0001% to 0.50%;
Mg: 0.0001% to 0.010%;
Ca: 0.0001% to 0.010%; and
REM: 0.0001% to 0.1%;
and balance composed of iron and inevitable impurities,
wherein an average value of an X-ray random intensity ratio of a {100} <011> to {223}<110> orientation group at least in a sheet thickness central portion that is in a sheet thickness range of ⅝ to ⅜ from a steel sheet surface is 1.0 to 6.0, an X-ray random intensity ratio of a {332} <113> crystal orientation is 1.0 to 5.0; and
rC which is an r value in a direction perpendicular to a rolling direction is 0.70 to 1.10, and r30 which is an r value in a direction that forms an angle of 30° with respect to the rolling direction is 0.70 to 1.10.
2. The hot-rolled steel sheet according to claim 1 ,
wherein rL which is an r value in the rolling direction is 0.70 to 1.10, and r60 which is an r value in a direction that forms an angle of 60° with respect to the rolling direction is 0.70 to 1.10.
3. The hot-rolled steel sheet according to claim 1 ,
wherein one or two or more of bainite, martensite, pearlite, and austenite are present in the hot-rolled steel sheet, and a proportion of grains having a dL/dt, which is a ratio of a length in the rolling direction dL to a length of a sheet thickness direction dt, of 3.0 or less in crystal grains in the structures is 50% to 100%.
4. The hot-rolled steel sheet according to claim 1 ,
wherein an area proportion of crystal grains having a grain diameter of more than 20 μm in a total area of a metallic structure in the hot-rolled steel sheet is 0% to 10%.
5. A cold-rolled steel sheet obtained through cold rolling of the hot-rolled steel sheet according to claim 1 ,
wherein the average value of the X-ray random intensity ratio of the {100} <011> to {223} <110> orientation group at least in the sheet thickness central portion is 1.0 to less than 4.0, the X-ray random intensity ratio of the {332} <113> crystal orientation is 1.0 to 5.0; and
rC which is the r value in a direction perpendicular to the rolling direction is 0.70 to 1.10, and r30 which is the r value in a direction that forms an angle of 30° with respect to the rolling direction is 0.70 to 1.10.
6. The cold-rolled steel sheet according to claim 5 ,
wherein rL which is an r value in the rolling direction is 0.70 to 1.10, and r60 which is an r value in a direction that forms an angle of 60° with respect to the rolling direction is 0.70 to 1.10.
7. The cold-rolled steel sheet according to claim 5 ,
wherein one or two or more of bainite, martensite, pearlite, and austenite are present in the cold-rolled steel sheet, and a proportion of grains having a dL/dt, which is a ratio of a length in the rolling direction dL to a length of a sheet thickness direction dt, of 3.0 or less in crystal grains in the structures is 50% to 100%.
8. The cold-rolled steel sheet according to claim 5 ,
wherein an area proportion of crystal grains having a grain diameter of more than 20 μm in a total area of a metallic structure in the cold-rolled steel sheet is 0% to 10%.
9. A galvanized steel sheet further comprising a galvanized coating layer or a galvanealed coating layer on a surface of the cold-rolled steel sheet according to claim 5 ,
wherein the average value of the X-ray random intensity ratio of the {100} <011> to {223} <110> orientation group at least in the sheet thickness central portion is 1.0 to less than 4.0, the X-ray random intensity ratio of the {332} <113> crystal orientation is 1.0 to 5.0; and
rC which is the r value in a direction perpendicular to the rolling direction is 0.70 to 1.10, and r30 which is the r value in a direction that forms an angle of 30° with respect to the rolling direction is 0.70 to 1.10.
10. The galvanized steel sheet according to claim 9 ,
wherein rL which is an r value in the rolling direction is 0.70 to 1.10, and r60 which is an r value in a direction that forms an angle of 60° with respect to the rolling direction is 0.70 to 1.10.