| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a steel plate for a fully high-ductile ultrahigh strength welded pipe equivalent to an X150 grade, and a steel pipe and a method for manufacturing the same. <P>SOLUTION: The steel plate for a high-ductile ultrahigh-strength welding steel pipe contains, by mass%, C: 0.09-0.11%, Si: 0.05-0.20%, Mn: 1.0-1.5%, Al: 0.01-0.08%, Cu: 2.0-4.0%, Nb: 0.05-0.07%, Ti: 0.015-0.025%, one or more selected from Cr: 0.05-0.6%, Mo: 0.05-0.6%, V: 0.01-0.1%, and B: 0.0005-0.003%, and the balance being Fe and inevitable impurities. The metal structure is bainite. In addition, the product of the tensile strength (MPa) in the rolling direction and the uniform elongation (%) in one direction is 8,500 or more. <P>COPYRIGHT: (C)2013,JPO&INPIT |
