High-strength cold-rolled steel sheet having excellent uniform elongation and hole expandability

1. A high-strength cold-rolled steel sheet having excellent uniform elongation and hole expandability comprising:

in mass %,

C: 0.01 to 0.4%;

Si: 0.001 to 0.929%;

Mn: 0.001 to 4.0%;

P: 0.001 to 0.15%;

S: 0.0005 to 0.03%;

Al: 0.001 to 0.929%;

N: 0.0005 to 0.01%; and

O: 0.0005 to 0.01%; in which Si+Al is limited to 0.93% or less, and

a balance being composed of iron and inevitable impurities, wherein

at a sheet thickness center portion being a range of ⅝ to ⅜ in sheet thickness from the surface of the steel sheet, 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> is 5.0 or less, and a pole density of the {332}<113> crystal orientation is 4.0 or less,

a metal structure contains 5 to 80% of ferrite, 5 to 80% of bainite, and 0.9% or less of martensite in terms of an area ratio and the total of martensite, pearlite, and retained austenite is 5% or less, and

an r value (rC) in a direction perpendicular to a rolling direction is 0.70 or more and an r value (r30) in a direction 30° from the rolling direction is 1.10 or less.

2. The high-strength cold-rolled steel sheet having excellent uniform elongation and hole expandability according to claim 1 , wherein

an r value (rL) in the rolling direction is 0.70 or more and an r value (r60) in a direction 60° from the rolling direction is 1.10 or less.

3. The high-strength cold-rolled steel sheet having excellent uniform elongation and hole expandability according to claim 1 , wherein

in the metal structure, a mean volume diameter of crystal grains is 7 μm or less, and an average value of a ratio of, of the crystal grains, a length dL in the rolling direction to a length dt in a sheet thickness direction: dL/dt is 3.0 or less.

4. The high-strength cold-rolled steel sheet having excellent uniform elongation and hole expandability according to claim 1 , further comprising:

one type or two or more types of

in mass %,

Ti: 0.001 to 0.2%,

Nb: 0.001 to 0.2%,

B: 0.0001 to 0.005%,

Mg: 0.0001 to 0.01%,

Rem: 0.0001 to 0.1%,

Ca: 0.0001 to 0.01%,

Mo: 0.001 to 1.0%,

Cr: 0.001 to 2.0%,

V: 0.001 to 1.0%,

Ni: 0.001 to 2.0%,

Cu: 0.001 to 2.0%,

Zr: 0.0001 to 0.2%,

W: 0.001 to 1.0%,

As: 0.0001 to 0.5%,

Co: 0.0001 to 1.0%,

Sn: 0.0001 to 0.2%,

Pb: 0.001 to 0.1%,

Y: 0.001 to 0.10%, and

Hf: 0.001 to 0.10%.

5. The high-strength cold-rolled steel sheet having excellent uniform elongation and hole expandability according to claim 1 , wherein

on the surface, hot-dip galvanizing is performed.

6. The high-strength cold-rolled steel sheet having excellent uniform elongation and hole expandability according to claim 5 , wherein

after the hot-dip galvanizing, an alloying treatment is performed at 450 to 600° C.