Difference between BV E420 and BV E550 steel plate

BV E420 is a high-strength shipbuilding steel plate certified by Bureau Veritas (BV) . The "E" grade signifies it is impact tested at -40°C . It has a minimum yield strength of 420 MPa and tensile strength ranging from 530 to 680 MPa, with minimum elongation of 18% . The chemical composition is strictly controlled with carbon ≤0.20%, manganese ≤1.70%, and silicon ≤0.55% . This grade can be supplied in normalized, quenched and tempered (QT), or thermomechanical controlled processed (TMCP) conditions . It is widely used for hull construction, decks, and structural components of ships and offshore structures operating in cold marine environments .

BV E550 Steel Plate

BV E550 is an extra-high-strength marine steel also certified by Bureau Veritas (BV) with impact toughness tested at -40°C . The "550" denotes a minimum yield strength of 550 MPa . It has a tensile strength ranging from 670 to 830 MPa and minimum elongation of 16% . The chemical composition features carbon ≤0.20%, manganese ≤1.70%, and microalloying elements . This grade requires advanced processing and is typically supplied in quenched and tempered (QT) or TMCP conditions . It is designed for demanding structural components in shipbuilding, offshore drilling units, and marine equipment requiring superior strength-to-weight ratio.

Both BV E420 and BV E550 are BV-certified high-strength marine steels with excellent low-temperature toughness tested at -40°C, ensuring reliable performance in harsh marine environments . Their primary difference lies in strength level: E420 offers a minimum yield strength of 420 MPa with tensile strength of 530-680 MPa, suitable for general high-strength hull construction and offshore structures , while E550 provides a substantially higher minimum yield strength of 550 MPa with tensile strength reaching 670-830 MPa, designed for extra-high-strength applications in critical load-bearing components . 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 mechanical properties while maintaining good weldability for marine service.

Chemical Composition

Mechanical Property