Difference between LR EH42 and LR EH55 steel plate

LR EH42 is an extra-high-strength marine steel plate certified by Lloyd's Register (LR) . The "EH" designation signifies it is impact tested at -40°C, ensuring excellent toughness for vessels operating in cold environments . It has a minimum yield strength of 420 MPa and tensile strength ranging from 530 to 680 MPa, with minimum elongation of 20% . Its chemical composition is strictly controlled with carbon ≤0.20% and manganese ≤1.70% . This grade is widely used for hull structures, offshore platforms, and demanding marine components requiring good weldability .

LR EH55 is an ultra-high-strength marine steel plate also certified by Lloyd's Register (LR) , with impact toughness tested at -40°C . The "55" denotes a minimum yield strength of 550 MPa and tensile strength ranging from 670 to 830 MPa, with minimum elongation of 18% . Impact energy requirements are 37J (transverse) or 55J (longitudinal) at -40°C . Its chemical composition is similar to EH42 with carbon ≤0.20% and manganese ≤1.70% . This grade is designed for the most demanding structural components in large vessels, offshore platforms, and ice-strengthened ships requiring superior strength-to-weight ratio.

Both LR EH42 and LR EH55 are LR-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: EH42 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 EH55 provides a substantially higher minimum yield strength of 550 MPa with tensile strength reaching 670-830 MPa, designed for more demanding load-bearing applications requiring superior strength-to-weight ratio . Both grades feature controlled chemical composition (carbon ≤0.20%, manganese ≤1.70%) and maintain good weldability for critical marine service. 

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Mechanical Property