The steel for ice breaking vessels is required to have an excellent notch toughness at low temperatures and a good weldability and to meet the strict requirements in terms of workability and cost. The first report discussed the base-metal properties and joint performance of the 40 mm thick steel plate newly developed for ice breaking vessels. The present report discusses 75 mm thick steel plate also newly developed for the bow part, which has to meet severer requirements. The developed material is the 50 kgf/mm² high tensile strength steel of 36 kgf/mm² yield point manufactured by the CLC process. The test results showed that this new heavy plate has good mechanical properties, weldability and workability. It was also indicated that an ice breaking vessel to be made of this steel would be sufficiently safe against brittel fracture.