| 摘要 |
PURPOSE:To obtain the titled Cr-Mo steel plate capable of holding sufficient strength and toughness even after subjected to SR at high temp. for long period in assembling a multilayer vessel, by providing a composition in which C content is remarkably reduced, B, Cu, and Ni are added in combination, the amounts of C, Si, and Mn are relatively controlled, and impurities such as P, S, etc., are reduced. CONSTITUTION:The steel plate for multilayer vessel has a composition consisting of, by weight, 0.03-0.10% C, 0.05.-0.90% Si, 0.30-0.90% Mn, <=0.020% P, <=0.010% S, 0.05-0.35% Cu, 0.05-0.35% Ni, 0.40-1.60% Cr, 0.20-0.70% Mo, 0.0003-0.0020% B, 0.005-0.100% solAl, <=0.010% Sn, <=0.010% Sb, <=0.010% As, and the balance Fe and satisfying the conditions in an equation as well as in an inequality. Said steel plate is the one of <=32mm thick having a bainite structure, capable of welding without preheating, and maintaining high strength and high toughness even after subjected to high-temp. and long-period stress relief annealing treatment, and further it has superior weld crack resistance as well.
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