CORROSION-RESISTANT STEEL MATERIAL SUPERIOR IN TOUGHNESS IN HEAVY-HEAT-INPUT WELD ZONE FOR SHIP AND MANUFACTURING METHOD THEREFOR

摘要

PROBLEM TO BE SOLVED: To provide a corrosion-resistant steel material for a ship, which shows excellent corrosion resistance even in a severely corrosive environment of sea water, such as a ballast tank of the ship, can extend a period before being repair-coated, can ease an operation of repair coating, and is superior in toughness at a weld zone even when being welded by heavy heat input.;SOLUTION: The steel material has a composition including particularly 0.0030 mass% or less O and 0.0005 to 0.0030% Ca which is added, and further 0.01 to 0.5 mass% W and/or 0.02 to 0.5 mass% Mo, 0.001 to 0.2 mass% Sn and/or 0.01 to 0.2 mass% Sb which are added to the steel material, while further satisfying the following expressions (1) to (3): (1): ACP={1-(0.8×W+0.5×Mo)^0.3}×{1-(Sn+0.4×Sb)^0.3}≤0.50; (2): WI=C+Mn/6+Mo/5+V/5+W/10+Sn/2+Sb/2≤0.50; and (3): 0ACR={Ca-(0.18+130×Ca)×O}/(1.25×S)1.00.;COPYRIGHT: (C)2009,JPO&INPIT