PRODUCTION OF CAST SLAB HAVING FINE SUBBOUNDARY AND THICK STEEL PLATE HAVING FINE METALLIC STRUCTURE

摘要

PURPOSE: To form a fine γ-structure by activating a γ-subboundary formed at the time of solidification by means of rolling and allowing it to function as a nucleation site at the time of rolling recrystallization and to produce a thick steel plate excellent in strength and toughness. ;CONSTITUTION: A steel which has a composition consisting of, by weight, 0.01-0.17% C, 0.01-0.6% Si, 0.2-2.0% Mn, 0.005-0.1% Al, 0.003-0.015% B, and the balance Fe with inevitable impurities and further containing, if necessary, one or ≥2 kinds among ≤0.05% Nb, ≤0.05% Ti, ≤1.0% Cu, ≤2.5% Ni, ≤1.0% Cr, ≤0.5% Mo, and ≤0.1% V us cast and then cooled from 1480-1400°C down to ≤1200°C at ≤50°C/min cooling rate, by which a fine subboundary is formed. Further, the resulting cast slab is subjected to direct rolling to perform gamma refining, by which the toughness of the steel plate is improved.;COPYRIGHT: (C)1993,JPO&Japio