| 摘要 |
The present invention provides steel plate for high strength line pipe suppressing the rise in yield strength in the longitudinal direction of expanded steel pipe due to the heating at the time of coating to prevent corrosion and superior in strain aging resistance and steel pipe for the material for the same, that is, high strength steel pipe for line pipe superior in strain aging resistance characterized in that a base material having a composition of chemical elements containing, by mass%, Mo: over 0% to less than 0.15% and Mn: 1.7 to 2.5%, satisfying Mo/Mn: over 0 to 0.08, containing C, Si, P, S, Al, Ti, N, and B, furthermore containing one or more of Ni, Cu, and Cr, having a balance of iron and unavoidable impurities, having a P value of 2.5 to 4.0 in range, and having a metallurgical structure comprised of bainite and martensite: P - value = 2.7 �¢ C + 0.4 �¢ Si + Mn + 0.8 �¢ Cr + 0.45 ( Ni + Cu ) + 2 �¢ Mo .
Furthermore, it may contain one or more of Nb, V, Ca, REM, and Mg. |
