| 摘要 |
PROBLEM TO BE SOLVED: To provide an electric-resistance-welded steel tube made from plain steel to be flare-worked superior in plating properties, the peeling resistance of a plated film when flare-worked, workability, corrosion resistance of a groove in a corrosive wet environment and electric-resistance-weldability when electric-resistance-welded. SOLUTION: The electric-resistance-welded steel tube has a steel composition including, by mass%, 0.005-0.04% C, 0.15-0.25% Si, 0.40-0.70% Mn,≤0.030% P,≤0.010% S, 0.010-0.080% Al,≤0.0080% N, and further one or more of≤0.30% Cu, 0.30% Ni,≤0.15% Cr,≤0.15% Mo,≤0.015% Ti,≤0.015% Nb,≤0.03% V and≤0.0050% Ca, while controlling Ceq.=C+Mn/6+(Cr+Mo+V)/5+(Cu+Ni)/15 into a range of 0.11 to 0.15%; has a non-heat treated structure in the base metal; has a TS of 450 MPa or lower and an elongation of 30% or lower; and a difference between a maximum value and a minimum value of Vickers hardness values distributing in a pipe perimeter direction in an amount of 25 or less. COPYRIGHT: (C)2007,JPO&INPIT
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