| 摘要 |
<p>A steel product for a cargo oil tank which has a chemical composition containing C: 0.01 to 0.2 %, Si: 0.01 to 1 %, Mn: 0.05 to 2 %, P: 0.05 % or less, S: 0.01 % or less, Ni: 0.01 to 1 %, Cu: 0.05 to 2 %, W: 0.01 to 1 %, Cr: 0.1 % or less, Al: 0.1 % or less, N: 0.001 to 0.01 %, and O (oxygen):0.0001 to 0.005 %. Preferably, alpha and beta, both being shown in the following, are 0.75 or less and 0.8 or less, respectively, and Ceq* represented by the formula (1) is 0.38 or less. alpha = (1-0.691xCu)x(1-0.221xNi)x(1-0.142xW) beta = (1-0.444xCu)x(1-0.156xNi)x(1-0.630xW) Ceq* = C + Mn/6 + Ni/15 + Cu/15 + W/10 + Cr/5 + Mo/5 ----(1) The above steel product for a cargo oil tank is excellent in the resistance to the corrosion over the whole of the surface or at a part of the surface under a circumstance of the corrosion by a crude oil and sea water, and also is excellent in the toughness of both of the mother material and a welded zone.</p> |
