| 摘要 |
Provided are a high-strength cold-rolled steel sheet containing, in mass%, C: 0.070-0.100%, Si: 0.050-0.70%, Mn: 2.40-2.80%, P: 0.025% or less, S: 0.0020% or less, Al: 0.020-0.060%, N: 0.0050% or less, Nb: 0.010-0.060%, Ti: 0.010-0.030%, B: 0.0005-0.0030%, Sb: 0.005-0.015%, Ca: 0.0015% or less, Cr: 0.01-2.00%, Mo: 0.01-1.00%, Ni: 0.01-5.00%, and Cu: 0.01-5.00%, with the remainder comprising Fe and unavoidable impurities, the high-strength cold-rolled steel sheet having a tensile strength of 980 MPa or above, having at a location one-fourth of the way through the thickness from the steel sheet surface a ferrite phase of an area ratio of 30% or more, at least one phase selected from the group consisting of bainite phases and martensite phases having a total area ratio of 40-65%, and cementite of an area ratio of 5% or less, and having at a location 50 μm down from the steel sheet surface in the thickness direction a ferrite phase of an area ratio of 40-55%; and a method for manufacturing the same. |
