What are difference between LR DH62 and LR DH69 steel plate?

LR DH62 is an ultra-high-strength marine steel plate certified by Lloyd's Register (LR) . The "DH" designation signifies it is a higher-strength grade with impact toughness tested at -20°C . It has a minimum yield strength of 620 MPa and tensile strength ranging from 720 to 890 MPa, with minimum elongation of 17% for thicknesses up to 100mm . The chemical composition is strictly controlled with carbon ≤0.20% and manganese ≤1.70%, featuring microalloying elements including Nb, V, and Ti . Impact energy requirements are minimum 62J (longitudinal) or 41J (transverse) at -20°C . This grade is designed for critically stressed structural components in modern shipbuilding and offshore engineering, offering an exceptional strength-to-weight ratio.

LR DH69 is an even higher ultra-high-strength marine steel plate also certified by Lloyd's Register (LR) with impact toughness tested at -20°C . The "69" denotes a minimum yield strength of 690 MPa . It has a higher tensile strength ranging from 770 to 940 MPa and minimum elongation of 16% for thicknesses up to 100mm . The chemical composition is similar to DH62 with carbon ≤0.20% and manganese ≤1.70%, along with microalloying elements . Impact energy requirements are minimum 69J (longitudinal) or 46J (transverse) at -20°C . This grade is designed for the most demanding load-bearing applications in shipbuilding, ultra-large container vessels, and offshore structures requiring maximum strength-to-weight ratio.

Both LR DH62 and LR DH69 are LR-certified ultra-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: DH62 offers a minimum yield strength of 620 MPa with tensile strength of 720-890 MPa, suitable for critically stressed structural components , while DH69 provides a substantially higher minimum yield strength of 690 MPa with tensile strength reaching 770-940 MPa, offering approximately 11% greater strength for the most demanding applications requiring maximum weight reduction . Both grades feature similar controlled chemical composition with carbon ≤0.20% and manganese ≤1.70%, and require advanced processing like TMCP or quenching and tempering to achieve their superior mechanical properties while maintaining good weldability for critical marine service .

Chemical Composition

Mechanical Property