Difference between DNV D420 and DNV D500 steel plate

DNV D420 is a high-strength structural steel plate certified by DNV (Det Norske Veritas) for marine and offshore applications . The "D" designation signifies that the material's impact toughness is tested and guaranteed at a moderate low temperature of -20°C . The number "420" indicates a minimum yield strength of 420 MPa. It has a tensile strength ranging from 530 to 680 MPa and minimum elongation of 18% for thicknesses up to 150mm . Impact energy requirements are typically 28J (transverse) or 42J (longitudinal) at -20°C . The chemical composition features carbon ≤0.20% and manganese ≤1.70%. This grade offers excellent weldability and formability, making it a cost-effective choice for general shipbuilding and marine structures.

DNV D500 is an extra-high-strength structural steel plate also certified by DNV with impact toughness tested at -20°C . The "500" denotes a minimum yield strength of 500 MPa . It has a tensile strength ranging from 610 to 770 MPa and minimum elongation of 16% for thicknesses up to 150mm . Impact energy requirements are higher, at 33J (transverse) or 50J (longitudinal) at -20°C . The chemical composition is strictly controlled with carbon ≤0.20% and manganese ≤1.70% . This grade requires advanced processing like quenching and tempering (QT) or TMCP to achieve its mechanical properties . It is suitable for demanding structural components in shipbuilding and mobile offshore drilling units where superior strength is required.

Both DNV D420 and DNV D500 are DNV-certified high-strength marine steels with impact toughness tested at -20°C, ensuring reliable performance in cold marine environments . Their primary difference lies in strength level: D420 offers a minimum yield strength of 420 MPa with tensile strength of 530-680 MPa, suitable for general high-strength hull construction where excellent fabricability is prioritized , while D500 provides a higher minimum yield strength of 500 MPa with tensile strength reaching 610-770 MPa, designed for more demanding load-bearing applications requiring superior strength-to-weight ratio. Both grades feature controlled chemical composition with carbon ≤0.20% and manganese ≤1.70% , and D500 requires more advanced processing like QT or TMCP to achieve its enhanced mechanical properties while maintaining good weldability for critical marine service.

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