Difference between LR EH55 and LR EH69 steel plate

LR EH55 is an ultra-high-strength marine steel plate certified by Lloyd's Register (LR) . The "EH" designation signifies it is an extra-high-strength grade with impact toughness tested at -40°C, ensuring excellent performance in harsh environments like Arctic waters . It has a minimum yield strength of 550 MPa and tensile strength ranging from 670 to 830 MPa, with minimum elongation of 18% for thicknesses up to 100mm . The chemical composition features carbon ≤0.20% and manganese ≤1.70%, with microalloying elements such as Nb and V . This grade is typically supplied in TMCP or quenched and tempered conditions and is used for critical hull structures and offshore platforms requiring superior strength .

LR EH69 is an ultra-high-strength marine steel plate also certified by Lloyd's Register (LR) with impact toughness tested at -40°C . The "69" denotes a minimum yield strength of 690 MPa and tensile strength ranging from 770 to 940 MPa, with minimum elongation of 16% for thicknesses up to 100mm . Impact energy requirements are minimum 69J (longitudinal) or 46J (transverse) at -40°C . The chemical composition is strictly controlled with carbon ≤0.20% and manganese ≤1.70%, featuring microalloying elements . This grade requires advanced processing (typically quenching and tempering) and is designed for the most demanding structural components in ultra-large container vessels, heavy-lift ships, and Arctic-class offshore units requiring maximum strength-to-weight ratio.

Both LR EH55 and LR EH69 are LR-certified ultra-high-strength marine steels with excellent low-temperature toughness tested at -40°C, ensuring reliable performance in harsh marine environments including Arctic conditions . Their primary difference lies in strength level: EH55 offers a minimum yield strength of 550 MPa with tensile strength of 670-830 MPa, suitable for high-strength hull construction and demanding offshore structures , while EH69 provides a substantially higher minimum yield strength of 690 MPa with tensile strength reaching 770-940 MPa, designed for the most critical load-bearing applications requiring maximum weight reduction. Both grades feature controlled chemical composition, but EH69 requires more advanced processing like quenching and tempering to achieve its superior mechanical properties while maintaining good weldability for critical marine service.

Chemical Composition

Mechanical Property