Steel material for crude oil tank and crude oil tank excellent in corrosion resistance

摘要

PROBLEM TO BE SOLVED: To provide a steel material for a crude oil tank which has excellent whole surface corrosion resistance on a top plate of a crude oil tank such as a tanker oil tank part and excellent local corrosion resistance on a bottom plate of the crude oil tank.SOLUTION: A steel material for a crude oil tank has a chemical composition comprising, in mass%, C: 0.03-0.18%, Si: 0.03-1.50%, Mn: 0.1-2.0%, P: 0.025% or less, S: 0.010% or less, Al: 0.005-0.10%, N: 0.008% or less, and Co: 0.001-0.5%, and one or two selected from W: 0.01-1.0% and Mo: 0.01-0.5%, with the balance being Fe and inevitable impurities.