Hot-rolled steel sheet
A hot-rolled steel sheet includes a specific chemical composition, and includes a microstructure represented by, in vol %: retained austenite: 2% to 30%; ferrite: 20% to 85%; bainite: 10% to 60%; pearlite: 5% or less; and martensite: 10% or less. A proportion of grains having an intragranular misorientation of 5° to 14° in all grains is 5% to 50% by area ratio, the grain being defined as an area which is surrounded by a boundary having a misorientation of 15° or more and has a circle-equivalent diameter of 0.3 μm or more.
1. A hot-rolled steel sheet, comprising:
a chemical composition represented by, in mass%:
C: 0.06% to 0.22%;
Si: 1.0% to 3.2%;
Mn: 0.8% to 2.2%;
P: 0.05% or less;
S: 0.005% or less;
Al: 0.01% to 1.00%;
N: 0.006% or less;
Cr: 0.00% to 1.00%;
Mo: 0.000% to 1.000%;
Ni: 0.000% to 2.000%;
Cu: 0.000% to 2.000%;
B: 0.0000% to 0.0050%;
Ti: 0.000% to 0.005%;
Nb: 0.000% to 0.200%;
V: 0.000% to 1.000%;
W: 0.000% to 1.000%;
Sn: 0.0000% to 0.2000%;
Zr: 0.0000% to 0.2000%;
As: 0.0000% to 0.5000%;
Co: 0.0000% to 1.0000%;
Ca: 0.0000% to 0.0100%;
Mg: 0.0000% to 0.0100%;
REM: 0.0000% to 0.1000%; and balance: Fe and impurities; and
a microstructure represented by, in vol %:
retained austenite: 9% to 30%;
ferrite: 60% to 85%;
bainite: 10% to 31%;
pearlite: 5% or less; and
martensite: 10% or less, wherein
a proportion of grains having an intragranular misorientation of 5° to 14° in all grains is 5% to 50% by area ratio, the grain being defined as an area which is surrounded by a boundary having a grain boundary misorientation of 15° or more and has a circle-equivalent diameter of 0.3 μm or more.
2. The hot-rolled steel sheet according to claim 1 , wherein, in the chemical composition, Cr: 0.05% to 1.00%, in mass %, is satisfied.
3. The hot-rolled steel sheet according to claim 2 , wherein, the chemical composition comprises,
Mo: 0.001% to 1.000%,
Ni: 0.001% to 2.000%,
Cu: 0.001% to 2.000%,
B: 0.0001% to 0.0050%,
Ti: 0.001% to 0.005%,
Nb: 0.001% to 0.200%,
V: 0.001% to 1.000%,
W: 0.001% to 1.000%,
Sn: 0.0001% to 0.2000%,
Zr: 0.0001% to 0.2000%,
As: 0.0001% to 0.5000%,
Co: 0.0001% to 1.0000%,
Ca: 0.0001% to 0.0100%,
Mg: 0.0001% to 0.0100%, or
REM: 0.0001% to 0.1000%, or
any combination thereof.
4. The hot-rolled steel sheet according to claim 1 , wherein, the chemical composition comprises,
Mo: 0.001% to 1.000%,
Ni: 0.001% to 2.000%,
Cu: 0.001% to 2.000%,
B: 0.0001% to 0.0050%,
Ti: 0.001% to 0.005%,
Nb: 0.001% to 0.200%,
V: 0.001% to 1.000%,
W: 0.001% to 1.000%,
Sn: 0.0001% to 0.2000%,
Zr: 0.0001% to 0.2000%,
As: 0.0001% to 0.5000%,
Co: 0.0001% to 1.0000%,
Ca: 0.0001% to 0.0100%,
Mg: 0.0001% to 0.0100%, or
REM: 0.0001% to 0.1000%, or
any combination thereof.