| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-strength cold-rolled thin steel sheet, that has a high proportional limit and having excellent bendability, and to provide a production method thereof.SOLUTION: The high-strength cold-rolled thin steel sheet has: a composition in which, in mass%, C: 0.04 to 0.25%, Si: 0.30% or less, Mn: 0.1 to 2.0%, Al: 0.10% or less, and N: 0.010% or less are contained, and furthermore one or two selected from Ti: 0.01 to 1.00%, and V: 0.01 to 1.00%, are contained by adjusting the same such that (12/48)×Ti+(12/51)×V≥0.04 and C≥0.9×((12/48)×Ti+(12/51)×V) are satisfied; and a structure in which the ferrite phase occupying 95% or more in an area ratio is the main phase, the deposition of less than 10 nm is 5.0×10pieces/μmor more, and the dislocation density is 5.0×10mor more, and in which the dislocation is tangled. Thereby, a cold-rolled annealed thin steel sheet having a tensile strength: 980 MPa or more, a high proportional limit of the proportional limit being 0.60 TS or more, and also excellent bendability is obtained. |
