STEEL MATERIAL, SHIP BALLAST TANK AND HOLD FORMED USING SAID STEEL MATERIAL, AND SHIP EQUIPPED WITH SAID BALLAST TANK OR HOLD

摘要

The steel material has a predetermined chemical composition and has a soft structure and a hard structure. The Sn concentration ratio, which is the ratio of the Sn concentration in the hard texture to the Sn concentration in the soft structure, is 1.2 or more and less than 6.0.