Difference between LR DH36 and LR DH55 steel plate

LR DH36 is a higher-strength structural steel plate certified by Lloyd's Register (LR) for shipbuilding and marine applications . 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 widely used for hull structures, offshore platforms, and shipbuilding components such as bulk carriers and container ships.

LR DH55 is an extra-high-strength marine steel plate also certified by Lloyd's Register (LR) with impact toughness tested at -20°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% for thicknesses up to 100mm . Impact energy requirements are minimum 55J (longitudinal) or 37J (transverse) at -20°C . The chemical composition features carbon ≤0.20% and manganese ≤1.70%, with microalloying elements including Nb and V . This grade is designed for critical, highly stressed structural members in shipbuilding and offshore applications.

Both LR DH36 and LR DH55 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, while DH55 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 . Both grades feature controlled chemical composition and maintain good weldability for critical marine service.

Chemical Composition

Mechanical Property