| 摘要 |
PROBLEM TO BE SOLVED: To provide a seamless steel pipe for oil well use having excellent expandability which exhibits excellent expandability to expansion at an expansion rate of >30% in spite of its high strength satisfying a tensile strength (TS) of≥600 MPa. SOLUTION: The seamless steel pipe has a composition comprising 0.05 to 0.30% C, 0.2 to 2% Si, 0.7 to 4.0% Mn,≤0.03% P,≤0.015% S,≤0.007% N and≤0.005% O, or further comprising one or more kinds of metals selected from Al, Cr, Ni, Cu, Nb, V, Ti, Mo, B and Ca by prescribed amounts, and the balance Fe with inevitable impurities, and has a structure comprising a retainedγphase by a phase fraction of≥5 vol.%. COPYRIGHT: (C)2006,JPO&NCIPI
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