| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a cold rolled steel sheet which can obtain uniform appearance and shape uniformity after press working, and to provide a method for producing the same. Ž<P>SOLUTION: The Ti-added IF (Interstitial Free) steel sheet is provided. In the sheet thickness surface layer part from each surface to 10 μm in both the sides of the steel sheet, the content (mass%) of the Ti element contained in precipitates with a size of <20 nm is controlled to ≤9% to the total Ti content (mass%) in the steel sheet. Upon production, it is characterized in that slab heating is performed under the conditions where heating temperature is 1,000 to <1,200°C, and also, heating time in the temperature range of ≥1,000°C is ≤3.0 hr, cooling is performed in such a manner that the steel sheet surface temperature lies in the range from (Ar3 transformation point-300°C) to Ar3 transformation point, and subsequently, finish rolling is performed in such a manner that the steel sheet surface temperature upon completion of the finish rolling is controlled to Ar3 transformation point or above, immediately, cooling is performed, and it is coiled at ≥650°C. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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