LOW C-CR-MO STEEL USED UNDER DAMP STEAM

PURPOSE:To provide the titled economical steel excellent in EC resistance, weldability, strength and toughness by specifying a composition consisting of C, Si, Mn, Cr, Mo, Nb, V and Fe. CONSTITUTION:A low C-Cr-Mo steel has a composition consisting of, by weight, 0.02-0.14% C, 0.45-0.90% Si, 0.30-0.80% Mn, 0.70-1.60% Cr, 0.005-0.05% Nb and/or 0.005-0.08% V and the balance essentially Fe except inevitable impurities. This steel shows excellent EC resistance and weldability when used under damp steam and is capable of improving economical efficiency by lowering preheating temp. The steel showing the above properties can be obtained by refining a steel under component regulation into the above composition, subjecting it to rolling or forging by the ordinary method and then carrying out normalizing and successive tempering or annealing.