HIGH TOUGHNESS AND HIGH STRENGTH UNTEMPERED STEEL, AND ITS PRODUCTION

摘要

PURPOSE: To provide a high toughness and high strength untempered steel, which has, in a non-heat treated state, the mechanical properties equal to or higher than those of a heat treated steel, and its production. ;CONSTITUTION: The untempered steel with high toughness and high strength has a composition consisting of, by weight, 0.35-0.45% C, 0.15-0.35% Si, 0.80-1.50% Mn, 0.005-0.050% S, ≤0.30% Cr, 0.01-0.05% Al, 0.05-0.15% of V+Nb, ≤0.03% Ti, 0.006-0.020% N, ≤0.03% P and ≤0.0050% O₂ both as impurities, and Fe with impurities inevitably accompanying at steel manufacture. By this method, ≥90 kgf/mm² tensile strength and ≥5 kgf-m/cm² impact toughness in the KS 3 specimen can be secured.;COPYRIGHT: (C)1995,JPO