PURPOSE: To obtain a high tension steel for a structural material with improved corrosion resistance and weldability by reducing the amounts of O and Mn in a low C-P-low S-low N steel, adding Ca, and carrying out rolling and accelerated cooling.
CONSTITUTION: This P-contg. low-Mn high-tension steel with high weldability and corrosion resistance consists of ≤0.07% C, ≤1.0% Si, ≤1.0% Mn, 0.05W 0.20% P, ≤0.010% S, 0.003W0.2% Al, ≤0.004% N, 0.002W0.010% Ca, ≤0.0030% O and the balance essentially Fe or further contains ≤2.0% in total of one or more among Cu, Ni, Cr, and Mo. To the composition may be added ≤0.15% in total of one or more among Nb, V, Ti, Zr, Ta and B. The steel is rolled and acceleratedly cooled. Since the steel has ≥about 50kg/mm2 strength, superior durability and weldability, it is suitable for use as a material for a welded structure used in a corrosive environment.
WATANABE TSUNEYASU
KANETANI KEN
OKAMOTO KENTAROU
TSUDA YUKIO
