THICK STEEL PLATE HAVING REDUCED MATERIAL ANISOTROPY AND EXCELLENT HAZ TOUGHNESS AND LOW TEMPERATURE BASE METAL TOUGHNESS

摘要

PROBLEM TO BE SOLVED: To provide a thick steel plate having reduced material anisotropy and excellent HAZ toughness and low temperature base metal toughness.;SOLUTION: The thick steel plate has a composition comprising 0.030 to 0.10% C, ≤1.0% Si, 0.8 to 2.0% Mn, ≤0.03% P, ≤0.01% S, 0.01 to 0.10% Al, ≤0.035% Nb, 0.015 to 0.03% Ti, 0.0010 to 0.0035% B and 0.0050 to 0.01% N, and in which the average circle equivalent diameter of old austenitic grains is ≤100 μm, also, the flattening ratio (major axis/minor axis) thereof is ≤2.5, and further, inequality; 1.5≤[Ti]/[N]≤4 and inequality; 40≤X value≤160 are satisfied: wherein, X value=500[C]+32[Si]+8[Mn]-9[Nb]+14[Cu]+17[Ni]-5[Cr]-25[Mo]-34[V].;COPYRIGHT: (C)2009,JPO&INPIT