Difference between LR DH42 and LR DH50 steel plate

LR DH42 is an extra-high-strength marine steel plate certified by Lloyd's Register (LR) for shipbuilding and offshore applications . The "D" designates its delivery condition (normalized or normalized rolled) and "H" indicates high strength . It has a minimum yield strength of 420 MPa and tensile strength ranging from 530 to 680 MPa, with minimum elongation of 20% for thicknesses up to 100mm . Impact energy requirements at -20°C are minimum 42J (longitudinal) or 28J (transverse) . The chemical composition features carbon ≤0.20% and manganese ≤1.70% . It is widely used for hull construction, offshore platforms, and marine structures requiring reliable strength in moderate cold environments.

LR DH50 is also an extra-high-strength marine steel plate certified by Lloyd's Register (LR) with impact toughness tested at -20°C . The "50" denotes a minimum yield strength of 500 MPa and tensile strength ranging from 610 to 770 MPa, with minimum elongation of 18% for thicknesses up to 100mm . Impact energy requirements are minimum 50J (longitudinal) or 33J (transverse) at -20°C . The chemical composition is similar to DH42 with carbon ≤0.20% and manganese ≤1.70%, featuring microalloying elements including Nb, V, and Ti. This grade is designed for more demanding structural components in shipbuilding and offshore structures requiring superior strength.

Both LR DH42 and LR DH50 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: DH42 offers a minimum yield strength of 420 MPa with tensile strength of 530-680 MPa, suitable for general high-strength hull construction and offshore structures, while DH50 provides a higher minimum yield strength of 500 MPa with tensile strength reaching 610-770 MPa, designed for more demanding load-bearing applications requiring superior strength . Both grades feature controlled chemical composition with carbon ≤0.20% and require advanced processing to achieve their mechanical properties while maintaining good weldability for marine service.

Chemical Composition

Mechanical Property