| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a thick wall seamless steel pipe with a wall thickness exceeding 30 mm, which has high strength and high toughness and is particularly suitable for a mechanical structural member such as of a boom for a crane. <P>SOLUTION: The seamless steel pipe is composed of low alloy steel including, in terms of mass%, C: 0.01-0.20%, Si: 0.05-1.0%, Mn: 0.05-1.2%, Cr: 0.50-1.50%, Mo: 0.50-1.50%, Nb: 0.002-0.10%, Al: 0.005-0.10%, and one or two kinds of Ti: 0.003-0.050% and V: 0.01-0.20%, the balance being Fe and impurities, in which Ni, in the impurities, is less than 0.10%, Cu is 0.20% or less, P is 0.025% or less, S is 0.005% or less, N is 0.007% or less, and B is less than 0.0003%. The pipe has a tensile strength of 950 MPa or more, a yielding strength of 850 MPa or more, a Charpy absorption energy of 60 J or more at -40°C, and a wall thickness exceeding 30 mm. <P>COPYRIGHT: (C)2013,JPO&INPIT</p> |
