Bainite-containing-type high-strength hot-rolled steel sheet having excellent isotropic workability and manufacturing method thereof

1. A bainite-containing high-strength hot-rolled steel sheet, comprising: in mass %,

C: greater than 0.07 to 0.2%;

Si: 0.001 to 2.5%:

Mn: 0.01 to 4%;

P: 0.15% or less (not including 0%);

S: 0.03% or less (not including 0%);

N: 0.01% or less (not including 0%);

Al: 0.001 to 2%; and

a balance being composed of Fe and inevitable impurities, wherein an average value of pole densities of the {100}<011> to {223}<110> orientation group represented by respective crystal orientations of {100}<011>, {116}<110>, {114}<110>, {113}<110>, {112}<110>,{335}<110>, and {223}<110> at a sheet thickness center portion being a range of ⅝ to ⅜ in sheet thickness from the surface of the steel sheet is 4.0 or less, and a pole density of the {332}<113>crystal orientation is 4.8 or less, an average crystal grain diameter is 10 μm or less and a Charpy fracture appearance transition temperature vTrs is −20° C. or lower, and a microstructure is composed of 35% or less in a structural fraction of pro-eutectoid ferrite and a balance of a low-temperature transformation generating phase.

2. The bainite-containing high-strength hot-rolled steel sheet according to claim 1 , further comprising:

one or two or more of in mass %,

Ti: 0.015 to 0.18%,

Nb: 0.005 to 0.06%,

Cu: 0.02 to 1.2%,

Ni: 0.01 to 0.6%,

Mo: 0.01 to 1%,

V: 0.01 to 0.2%, and Cr: 0.01 to 2%.

3. The bainite-containing high-strength hot-rolled steel sheet according to claim 1 , further comprising:

one or two or more of in mass %,

Mg: 0.0005 to 0.01%,

Ca: 0.0005 to 0.01%, and REM: 0.0005 to 0.1%.

4. The bainite-containing high-strength hot-rolled steel sheet according to claim 1 , further comprising: in mass %, B: 0.0002 to 0.002%.