POSCO Holdings Inc.
SOUR-RESISTANT HEAVY-WALL STEEL PLATE HAVING EXCELLENT LOW-TEMPERATURE TOUGHNESS AND POST-HEAT TREATMENT CHARACTERISTICS AND METHOD FOR MANUFACTURING SAME

Abstract:

Provided are: a SOUR-resistant heavy-wall steel plate having excellent low-temperature toughness and post-heat treatment characteristics; and a method for manufacturing the same. The SOUR-resistant heavy-wall steel plate of the present invention comprises: in terms of weight %, 0.02-0.06% of C; 0.5% or less of Si (excluding 0%); 0.8-2.0% of Mn; 0.03% or less of P; 0.003% or less of S; 0.06% or less of Al; 0.01% or less of N; 0.005-0.1% of Nb; 0.005-0.05% of Ti; 0.0005-0.005% of Ca; one or more selected from 0.05-0.5% of Ni, 0.05-0.5% of Cr, 0.02-0.4% of Mo, and 0.005-0.1% of V; and the remainder Fe and unavoidable impurities, wherein the heavy-wall steel plate satisfies relational expressions 1-3, and has a percent ductile fracture of 85% or more in the drop weight tear test (DWTT) at -20.degree. C.