Difference between LR DH36 and LR DH69 steel plate

LR DH36 is a high-strength shipbuilding steel plate certified by Lloyd's Register (LR) . The "D" grade signifies it is impact tested at -20°C . It has a minimum yield strength of 355 MPa and tensile strength ranging from 490 to 620 MPa, with minimum elongation of 21% . The chemical composition features carbon ≤0.18% and manganese 0.90-1.60% . This grade is typically supplied in normalized or thermomechanical controlled processed (TMCP) conditions . It is widely used for hull structures, offshore platforms, and shipbuilding components such as bulk carriers and container ships.

LR DH69 is an 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 and tensile strength ranging from 770 to 940 MPa, with minimum elongation of 16-18% . Impact energy requirements are minimum 69J (longitudinal) or 46J (transverse) at -20°C . The chemical composition features carbon ≤0.20% and manganese ≤1.70%, with microalloying elements including Nb, V, Ti, Cu, Cr, Ni, and Mo . This grade requires advanced processing such as TMCP or quenching and tempering and is designed for the most critically stressed structural components in modern shipbuilding, ultra-large container vessels, and demanding offshore structures.

Both LR DH36 and LR DH69 are LR-certified 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: DH36 offers a minimum yield strength of 355 MPa with tensile strength of 490-620 MPa, suitable for general high-strength hull construction and secondary structures , while DH69 provides a substantially higher minimum yield strength of 690 MPa with tensile strength reaching 770-940 MPa, designed for the most demanding load-bearing applications requiring maximum weight reduction. Both grades feature controlled chemical composition, but DH69 requires more advanced processing like TMCP or QT to achieve its superior mechanical properties while maintaining good weldability for critical marine service.

Chemical Composition

Mechanical Property