| 摘要 |
PURPOSE:To manufacture a low-carbon Cr-Mo steel plate having high strength and toughness and excellent in creep-resisting property as well as in resistance to weld crack and erosion, by reducing the amount of C in the Cr-Mo steel, providing B with the addition of a proper amount of Al and the reduction of the amount of N, and further providing Cu in combination with Ni. CONSTITUTION:The Cr-Mo steel consists of 0.03-0.10% C, <1.00% Si, 0.20-0.75% Mn, <0.020% P, <0.015% S, 0.05-0.50% Cu, 0.05-0.50% Ni, 1.70-2.60% Cr, >0.75-1.25% Mo, 0.0003-0.0020% B, 0.005-0.100% sol.Al, and <0.005% N, or further contains at least 1 kind among 0.005-0.07% Nb, 0.005-0.07% V, and 0.0005-0.0070% Ca; the value of Pcm (weld crack-sensitive composition) represented by formula (1) is <=0.34.
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