| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel sheet superior in cold workability, which has a YS of less than 210 MPa, an El of 49% or more and a YR of less than 50%, and to provide a method of manufacturing therefor. SOLUTION: The steel sheet superior in cold workability includes a component composition comprising, by mass%, 0.40 to 0.80% C, 0.20 to 2.00% Si, more than 0.50 to 1.50% Mn, 0.001 to 0.150% Al, 0.018% or less P, 0.010% or less S, 0.0050% or less N and the balance Fe with unavoidable impurities; and includes a structure containing ferrite, graphite and cementite. The sum of volume fractions of ferrite, graphite and cementite occupying in the whole structure is 95% or more, a volume fraction of graphite (graphitization rate) occupying in the total volume of graphite and cementite is 40% or more, and the sum of a volume fractions of graphite and cementite existing in a ferrite grain occupying in the total volume of graphite and cementite is 15% or less. COPYRIGHT: (C)2010,JPO&INPIT |
