What are difference between BV D550 and BV D620 steel plate？

BV D550 is an extra-high-strength marine steel plate certified by Bureau Veritas (BV) . The "D" grade signifies it is impact tested at -20°C . It has a minimum yield strength of 550 MPa and tensile strength ranging from 670 to 830 MPa, with minimum elongation of 16% . The chemical composition is strictly controlled with carbon ≤0.20%, manganese ≤1.70%, and microalloying elements . This grade is typically supplied in quenched and tempered (QT) or thermomechanical controlled processed (TMCP) conditions . It is widely used for shipbuilding, offshore platforms, and marine engineering structures operating in cold environments.

BV D620 is an ultra-high-strength marine steel also certified by Bureau Veritas (BV) with impact toughness tested at -20°C . The "620" denotes a minimum yield strength of 620 MPa . It has a tensile strength ranging from 720 to 890 MPa and minimum elongation of 15% . The chemical composition features carbon ≤0.20%, manganese ≤1.70%, with strict control of phosphorus and sulfur . This grade requires advanced processing and is typically supplied in quenched and tempered (QT) or TMCP conditions . It is designed for the most demanding structural components in shipbuilding, ultra-deepwater offshore platforms, and Arctic-class vessels requiring maximum strength-to-weight ratio.

Both BV D550 and BV D620 are BV-certified extra-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: D550 offers a minimum yield strength of 550 MPa with tensile strength of 670-830 MPa, suitable for high-strength offshore structures , while D620 provides a substantially higher minimum yield strength of 620 MPa with tensile strength reaching 720-890 MPa, designed for the most demanding load-bearing applications requiring maximum strength-to-weight ratio . Both grades feature controlled chemical composition with carbon ≤0.20% and manganese ≤1.70% , and require advanced processing like QT or TMCP to achieve their superior mechanical properties while maintaining good weldability for critical marine service.

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Mechanical Property