Difference between LR DH32 and LR DH62 steel plate

LR DH32 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 315 MPa (46 ksi) and tensile strength ranging from 440 to 570 MPa (64-83 ksi), with minimum elongation of 22%. The chemical composition is strictly controlled with carbon ≤0.18% and manganese 0.90-1.60% . This grade is typically supplied in normalized or controlled rolled conditions and is widely used for hull structures and general shipbuilding components.

LR DH62 is an ultra-high-strength marine steel plate also certified by Lloyd's Register (LR) with impact toughness tested at -20°C . The "62" denotes 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 . Impact energy requirements are minimum 62J (longitudinal) or 41J (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 and offshore engineering.

Both LR DH32 and LR DH62 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: DH32 offers a minimum yield strength of 315 MPa with tensile strength of 440-570 MPa, suitable for general high-strength hull construction and secondary structures , while DH62 provides a substantially higher minimum yield strength of 620 MPa with tensile strength reaching 720-890 MPa, designed for the most demanding load-bearing applications requiring maximum weight reduction. Both grades feature controlled chemical composition, but DH62 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