| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a high-strength cold-rolled steel sheet excellent in bending workability, capable of sufficiently minimizing a rate of bending fracture starting from inclusions in bending. <P>SOLUTION: In the high-strength cold-rolled steel sheet excellent in bending workability, the steel sheet has a composition satisfying 0.12-0.3% C, 0.5% or less Si (including 0%), less than 1.5% Mn (excluding 0%), 0.15% or less Al (excluding 0%), 0.01% or less N (excluding 0%), 0.02% or less P (excluding 0%), and 0.01% or less S (excluding 0%), with the remainder including iron and inevitable impurities. A steel structure is a martensite single-phase structure, and, in a surface layer region from a surface of the steel sheet to a depth one-tenth the sheet thickness, the number of n-ary groups of inclusions determined by a specific n-th determination is 120 or less per 100 cm<SP POS="POST">2</SP>of a rolling plane, where the distance between outermost surfaces of two outermost particles of the group of inclusions in a steel sheet rolling direction is 100 μm or more. <P>COPYRIGHT: (C)2012,JPO&INPIT |
