| 摘要 |
PROBLEM TO BE SOLVED: To provide a cold rolled steel pipe which has satisfactory workability without causing a high cost in steel having a relatively large C content, and to provide a production method therefor. SOLUTION: The steel pipe comprises a prescribed amount of C and a mean r value of≥1.1, and in which the r value in a direction crossing the rolling direction (rC) is equal to or above the r value in the rolling direction (rL), and the intensity ratio in each X-ray reflecting surface of ä111} and ä100} of the sheet surfaces in the sheet thickness of 1/2 is≥3.0 and≤3.0, respectively. In the method of producing the high strength steel pipe having excellent workability, a structure consisting essentially of bainite and martensite is adopted to a hot rolled sheet subjected to cold rolling, the draft in the cold rolling is controlled to 25 to 95%, annealing is performed, and joining is carried out. COPYRIGHT: (C)2004,JPO&NCIPI
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