HIGH-STRENGTH STEEL PLATE WITH 980 MPA OR ABOVE TENSILE STRENGTH EXCELLENT IN LOW TEMPERATURE TOUGHNESS OF MULTI-LAYER JOINT

摘要

PURPOSE: A high-strength steel sheet with tensile strength over 980 MPa(Mega Pascal) and excellent low-temperature toughness of a multilayer welded joint is provided to reduce the production of MA(Martensite-Austenite) of IR-CGHAZ(Infrared-Coarsened Grain Heat Affected Zone). CONSTITUTION: A high-strength steel sheet with tensile strength over 980 MPa(Mega Pascal) and excellent low-temperature toughness of a multilayer welded joint consists of C(Carbon) 0.12~0.16wt.%, Si(Silicon) 0.05~0.5wt.%, Mn(Manganese) 0.8~1.2wt.%, Al(Aluminum) 0.01~0.07wt.%, Mo(Molybdenum) 0.5~0.8wt.%, Nb(Niobium) 0.025~0.08wt.%, B(Boron) 0.0004~0.002wt.%, Cr(Chromium) 0.2~0.8wt.%, V(Vanadium) 0.025~0.06wt.%, residual iron, and inevitable impurities. The MP value is 0.550 or greater, and the carbon equivalent is 0.63% or less.