EXTREMELY THICK STEEL SHEET AND METHOD OF MANUFACTURING THE EXTREMELY THICK STEEL SHEET

摘要

PURPOSE: An ultra thick steel plate and a manufacturing method thereof are provided to properly control the alloying constituents and the processing conditions to secure 510-660MPa of tensile strength(TS), 390Mpa of yield strength(YS) and 300J or greater of shock energy at -40=. CONSTITUTION: A manufacturing method of an ultra thick steel plate comprises the following steps. A slab plate strip is reheated at 950-1050=, SRT(Slab Reheating Temperature), wherein the slab plate is composed of, in wt%: C 0.05-0.10; Si 0.05-0.30; Mn 1.4-2.0; S_Al 0.02-0.04; P 0.012 or less; S 0.005 or less; Nb 0.01-0.03; Ti 0.01-0.02; Ca 0.03 or less; N 50ppm or less; the remainder Fe; and other inevitable impurities. The reheated plate is firstly rolled in the austenite recrystallization zone. The firstly-rolled plate is secondly rolled in the austenite non-recrystallization zone. The secondly-rolled plate is cooled to 450-600=.