| 摘要 |
PURPOSE:To manufacture a high toughness and high P-type weather resistant steel having superior weldability and giving a welded joint of superior performance by reducing the carbon equiv. of a steel and adding proper amounts of B and N as well as Ti or Zr. CONSTITUTION:The composition of a steel is composed of, by weight, <0.1% C, <0.75% Si, 0.5-1.2% Mn, 0.04-0.15% P, <0.007% S, 0.005-0.1% Al, 0.0003-0.002% B, 0.002-0.01% N, 0.15-0.6% Cu, 0.1-1% Cr, 0.002-0.05% Ti and/or Zr and the balance Fe with inevitable impurities and the carbon equiv. (Ceq) represented by the formula is regulated to <=0.35%.
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