Jfe Steel Corporation

Nobuko Mineji

Tadashi Inoue

Reiko Sugihara

Eiko Yasuhara

A cold-rolled steel sheet has a composition containing, by mass percent, 0.0040% or less of C, 0.02% or less of Si, 0.14% to 0.25% of Mn, 0.020% or less of P, 0.015% or less of S, 0.0040% or less of N, 0.020% to 0.070% of Al, 0.005% to 0.030% of Nb, 0.005% to 0.030% of Ti, (0.0003% to 0.0010% of the equivalent amount of solid solution B (from which the amount of B forming BN has been subtracted)), and the balance composed of Fe and inevitable impurities, wherein even when the rolling reduction of cold rolling is 85% or less, the average grain size of a ferrite structure is reliably 12.0 &#x3bc;m or less, and the relationship &#x2212;0.20&#x2266;&#x394;r&#x2266;0.20 can be reliably satisfied and which has an excellent earing property.

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Tokyo, Japan

Nobuko Mineji