Difference between LR DH46 and LR DH55 steel plate

LR DH46 is an extra-high-strength marine 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 460 MPa and tensile strength ranging from 570 to 720 MPa . Minimum elongation is 19% for thicknesses up to 100mm . Impact energy requirements are minimum 46J (longitudinal) or 31J (transverse) at -20°C . The chemical composition features carbon ≤0.20%, manganese ≤1.70%, with microalloying elements . This grade is typically supplied in normalized or controlled rolled conditions . It is widely used for shipbuilding, offshore platforms, and marine structures operating in cold environments.

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 . It has a tensile strength ranging from 670 to 830 MPa and minimum elongation of 18% . Impact energy requirements are minimum 55J (longitudinal) or 37J (transverse) at -20°C . The chemical composition includes carbon ≤0.20%, manganese ≤1.70%, with strict control of phosphorus and sulfur . This grade requires advanced processing and is typically supplied in normalized or TMCP conditions . It is designed for demanding structural components in shipbuilding and offshore applications where higher strength is required.

Both LR DH46 and LR DH55 are LR-certified extra-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: DH46 offers a minimum yield strength of 460 MPa with tensile strength of 570-720 MPa, suitable for general high-strength hull construction and offshore structures , while DH55 provides a 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 with carbon ≤0.20% and manganese ≤1.70% , and maintain good weldability for critical marine service.

Chemical Composition

Mechanical Property