| 摘要 |
PURPOSE:To obtain the titled steel plate having superior weld crack resistance and capable of being welded without preheating by providing a prescribed composition satisfying a specified relation among C, Si and Mn to a steel plate and by regulating the value showing sensitivity to cold cracking during welding. CONSTITUTION:This Cr-Mo steel plate of <=32mm thickness for a multilayered vessel consists of 0.02-0.10% C, 0.02-1.00% Si, 0.20-0.90% Mn, <=0.20% P, prescribed percentages of ten kinds of other elements and the balance Fe, satisfies formula I and has 0.33% Pcm defined by formula II and a bainite structure. The steel plate can be welded without preheating and has high strength and toughness even after stress relief annealing at a high temp. for a long time, so it is especially suitable for the manufacture of a multilayered vessel.
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