Patent ID: 8840738

Claim:
A cold-rolled steel sheet comprising: a component composition, comprising, in terms of % by mass: iron, C: 0.05-0.30%, Si: 3.0% or less (including 0%), Mn: 0.1-5.0%, P: 0.1% or less (including 0%), S: 0.010% or less (including 0%) and Al: 0.001-0.10%; and having a structure, comprising, in terms of area ratio: 10-80% of ferrite as a soft phase; less than 5% (including 0%) of a sum of retained austenite, martensite and a mixed structure of retained austenite and martensite; and a hard phase comprising at least one tempered substance selected from the group consisting of tempered martensite and tempered bainite; wherein, in a frequency distribution curve of a Kernel Average Misorientation value (KAM value), a relation between a proportion of frequency having a KAM value of 0.4° or less to a total frequency X KAM≦0.4° (unit: %) and an area ratio of ferrite V α (unit: %) satisfies X KAM≦0.4° /V α ≧0.8; and a proportion of frequency having a KAM value of 0.6-0.8° to a total frequency X KAM=0.6-0.80° is 10-20%; and wherein a dispersion state of cementite grains having an equivalent circle diameter of 0.1 μm or more and existing at an interface between the ferrite and the hard phase is three grains or less per 1 μm 2 of the hard phase.