| 摘要 |
PROBLEM TO BE SOLVED: To provide a cold-rolled steel sheet which is inexpensive, can be produced without reducing the productivity, is excellent in strain-aging resistance and has a low in-plane anisotropy of -0.20≤Δr≤0.20, and to provide a method for manufacture thereof. SOLUTION: The cold-rolled steel sheet has the following composition (%by mass): C: 0.010 to 0.040%, Si: 0.02% or less, Mn: 1.0 to 2.%, P: 0.02% or less, S: 0.015% or less, N: 0.004% or less, Al: 0.020 to 0.070%, and the remainder: Fe and unavoidable impurities, has a microtissue composed of a ferrite phase and a low temperature transformation phase wherein the volume ratio of the low temperature transformation phase is not less than 0.2% and less than 10%, has an AI of 50 MPa or less, satisfies -0.20≤Δr≤0.20, has a thickness of 0.5 mm or less, is excellent in strain-aging resistance and has a low in-plane anisotropy. COPYRIGHT: (C)2007,JPO&INPIT |
