| 摘要 |
PROBLEM TO BE SOLVED: To provide a cold rolled steel sheet having a tensile strength of 590 MPa or more and excellent in processability with good elongation by using precipitation strengthening of a fine carbide and a manufacturing method therefor.SOLUTION: There is provided a cold rolled steel sheet containing, by mass%, C:0.04 to 0.06%, Si+Al:0.05 to 0.10%, Mn:0.15 to 0.45%, P:less than 0.01%, Ti:0.12 to 0.16% with Tidefined by the following (1) formula having a composition satisfying the following (2) formula, volume fraction of a ferrite phase:90% or more, volume fraction of a cementite:less than 5%, recrystallization fraction of the ferrite phase:70% or more, Ti carbide (TiC) depositing in the ferrite phase with a structure having an average length of less than 15 nm and Ti deposition fraction of 90% or more and tensile strength of 590 MPa or more. Ti=Ti-(3.43N+1.5S) (1)1.2≤4C/Ti≤2.4(2) |
