| 摘要 |
PROBLEM TO BE SOLVED: To provide an advantageous method for producing a cold rolled steel sheet having excellent deep workability to a degree that satisfactory moldability can be realized in actual press molding, and an advantageous production method therefor.SOLUTION: The steel sheet has a composition comprising, by mass, 0.005% or less of C, 0.1 to 0.8% Si, 1.0 to 2.5% Mn, 0.1% or less of P, 0.02% or less of S, 0.01% or less of N and 0.1% or less of Al, and further comprising one or two kinds selected from 0.005 to 0.05% Ti and 0.01 to 0.08% Nb, and the balance Fe with inevitable impurities, and in which ferrite grain size is 7 μm or higher, the ratio of the length between the rolling direction of ferrite grains and the sheet thickness direction is 2.5% or lower, and the ratio occupied by large-angle grain boundaries in which the orientation difference between two crystals including the grain boundaries among ferrite grain boundaries is 15° or higher is 50% or higher of all the grain boundaries. |
