PRODUCTION OF WEATHER RESISTANT STEEL HAVING WELDABILITY AND =50KG/MM2 STRENGTH

摘要

PURPOSE:To obtain weather resistanct steel having high strength and weldability by refining specific low alloy steel consisting basically of C, Si, Mn, solAl, Cu Cr, hot-rolling the same and cooling acceleratively under specific conditions. CONSTITUTION:The steel consisting of 0.03-0.20% C, =0.6% Si, 0.5-2.5% Mn, 0.01-0.08% solAl, 0.1-2.0% Cu, 0.1-2.0% Cr, and if necessary, 0.01-1.0% Nb, 0.01-0.15% V, 0.01-0.15% Ti, =2.0Ni, =2.0% Mo, and the balance iron, and satisfying =0.22% low temp. cracking sensitive compsn. and =(25.8-0.18Vc)/78 carbon equiv. of accelerative cooling material is refined. The molten steel is hot rolled at =20% cumulative draft below the Ar3 point, and 650 deg.C-(Ar3-30 deg.C) finishing temp. After the hot rolled steel is cooled acceleratively at 4-25 deg.C/sec. for at least 80 deg.Ctemp. width down to =500 deg.C, the same is allowed to cool. Thus the weather resistant steel having excellent weldability and =50Kg/mm.2 strength is obtained.