COLD-ROLLED STEEL SHEET AND METHOD FOR MANUFACTURE THEREOF

摘要

Disclosed is a cold-rolled steel sheet which has the following composition (% by mass): C: 0.010-0.040%, Si: 0.02% or less, Mn: 1.0-2.5%, P: 0.02% or less, S: 0.015% or less, N: 0.004% or less, Al: 0.020-0.070%, and the remainder: Fe and unavoidable impurities, has a microtissue composed of a ferrite phase and a second phase wherein the volume ratio of the second phase is not less than 0.2% and less than 10%, has an AI of 50 MPa or less, satisfies the following requirement: -0.20=?r=0.20, and has a thickness of 0.5 mm. The steel sheet is inexpensive, can be produced without reducing the productivity, is excellent in strain-aging resistance and has a low in-plane anisotropy.