Difference between LR DH40 and LR DH62 steel plate

LR DH40 is a high-strength shipbuilding steel plate certified by Lloyd's Register (LR) for marine and offshore applications. The "DH" designation signifies it is a higher-strength grade with impact toughness tested at -20°C. It has a minimum yield strength of 390 MPa and tensile strength ranging from 510 to 660 MPa, with minimum elongation of 20%. Impact energy requirements at -20°C are minimum 39J (longitudinal) or 26J (transverse) for thicknesses up to 50mm. The chemical composition features carbon ≤0.18% and manganese 0.90-1.60%. This grade is typically supplied in normalized, quenched and tempered, or TMCP conditions. It is widely used for constructing large ships such as bulk carriers, oil tankers, and offshore platforms.

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 for enhanced properties. This grade requires advanced processing and is typically supplied in quenched and tempered (QT) or TMCP conditions. It is designed for the most critically stressed structural components in modern shipbuilding and offshore engineering, offering an exceptional strength-to-weight ratio.

Both LR DH40 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: DH40 offers a minimum yield strength of 390 MPa with tensile strength of 510-660 MPa, suitable for general high-strength hull construction and offshore structures, while DH62 provides a substantially higher minimum yield strength of 620 MPa with tensile strength reaching 720-890 MPa, offering approximately 59% greater strength for the most demanding load-bearing applications requiring maximum weight reduction. Both grades feature controlled chemical composition, with DH62 requiring more advanced processing like QT or TMCP and stricter alloying to achieve its superior mechanical properties while maintaining good weldability for critical marine service.

Chemical Composition

Mechanical Property