Difference between DNV B and DNV D steel plate

DNV B is an ordinary-strength structural steel certified by DNV (Det Norske Veritas) for shipbuilding and marine applications . It has a minimum yield strength of 235 MPa (34 ksi) and tensile strength ranging from 400 to 520 MPa . Impact toughness is tested at 0°C . The chemical composition features carbon ≤0.21%, manganese 0.80-1.20%, and silicon ≤0.35% . This grade is typically supplied in hot-rolled or normalized conditions . It is widely used for hull structures and general marine components where moderate strength is sufficient.

DNV D is also an ordinary-strength structural steel certified by DNV, with the same minimum yield strength of 235 MPa and tensile strength of 400-520 MPa as Grade B . However, the "D" designation signifies improved impact toughness tested at a lower temperature of -20°C . The chemical composition is controlled with carbon ≤0.21%, manganese 0.60-1.20%, and silicon ≤0.35%, with aluminum ≥0.015% for grain refinement . This grade is supplied in normalized, TMCP, or controlled rolled conditions . It is designed for shipbuilding and offshore structures operating in colder marine environments.

Both DNV B and DNV D are ordinary-strength marine steels with identical mechanical properties: minimum yield strength of 235 MPa and tensile strength of 400-520 MPa . Their primary difference lies in low-temperature toughness: DNV B is impact tested at 0°C, suitable for general marine applications, while DNV D is tested at -20°C, ensuring reliable performance in colder environments . Both grades feature controlled chemical composition with carbon ≤0.21% and maintain good weldability for marine service, with DNV D requiring additional grain refinement for enhanced low-temperature performance.

Chemical Composition

Mechanical Property