Difference between LR DH32 and LR DH42 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 590 MPa (64-83 ksi) . Minimum elongation is 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 DH42 is an extra-high-strength marine steel plate also certified by Lloyd's Register (LR) with impact toughness tested at -20°C . The "42" denotes a minimum yield strength of 420 MPa and tensile strength ranging from 530 to 680 MPa . Minimum elongation is 20% for thicknesses up to 100mm . Impact energy requirements are minimum 42J (longitudinal) or 28J (transverse) at -20°C . The chemical composition features carbon ≤0.20%, manganese ≤1.70%, with microalloying elements such as Nb and V . This grade requires advanced processing such as normalizing or quenching and tempering and is designed for demanding structural components in shipbuilding and offshore platforms .

Both LR DH32 and LR DH42 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 440-590 MPa, suitable for general high-strength hull construction and secondary structures, while DH42 provides a higher minimum yield strength of 420 MPa with tensile strength reaching 530-680 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, with DH42 requiring more advanced processing to achieve its enhanced mechanical properties.

Chemical Composition

Mechanical Property