| 摘要 |
PROBLEM TO BE SOLVED: To provide a seamless steel tube provided with high strength, stable toughness and excellent corrosion resistance and suitable for submarine flow-line, and to provide a method for producing the seamless steel tube. SOLUTION: The seamless steel tube as quenching, is composed, by mass%, of 0.03-0.08% C, 0.3-2.5% Mn, 0.001-0.10% Al, 0.02-1.0% Cr, 0.02-1.0% Ni, 0.02-0.8% Mo, 0.004-0.010% Ti, 0.002-0.008% N, 0.0005-0.005% Ca, 0-0.08%V, 0-1.0% Cu and the balance Fe with impurities, in which≤0.25% Si,≤0.05% P,≤0.005% S, <0.005%Nb and <0.0003% B, and has the structure of≤20 vol% polygonal ferrite,≤10 vol% mixed structure of martensite and retained austenite and the balance bainite; and a high strength thick seamless steel tube is obtained by tempering the above steel tube. COPYRIGHT: (C)2007,JPO&INPIT
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