| 摘要 |
An impeder for manufacturing a welded pipe which has an insulating case (4) and, housed therein, a laminate (10) of coated steel sheets (8) each having a steel sheet having a thickness of 0.3 mm or less and, formed on the surface thereof, an insulating coating film, characterized in that the steel sheet contains 1.5 to 20 % of Cr and 2.5 to 10 % of Si, has a total content of C a nd N of 100 ppm or less, contains one or more of Al, Mn and P in amounts of 5 % or less, 1 % or less and 1 % or less, respectively, the balance of the steel being Fe and inevitable impurities, and preferably the steel sheet has a resistivity of 60 .mu..OMEGA. .cndot. cm or more.
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