Difference between LR AH40 and LR AH46 steel plate

LR AH40 is a high-strength shipbuilding steel plate certified by Lloyd's Register (LR) . The "A" grade signifies it is impact tested at 0°C , ensuring reliable toughness for general marine environments . It has a minimum yield strength of 390 MPa and tensile strength ranging from 510 to 650 MPa , with a minimum elongation of 20% . The chemical composition features carbon ≤0.18% and manganese 0.90-1.60% . This grade is widely used for hull structures, decks, and offshore platforms .

LR AH46 is an extra-high-strength marine steel plate also certified by Lloyd's Register (LR) , designed for more demanding structural applications . It is impact tested at 0°C and has a minimum yield strength of 460 MPa and tensile strength ranging from 570 to 720 MPa , with a minimum elongation of 19% . The chemical composition features carbon ≤0.21% and manganese ≤1.70%, with microalloying elements such as Nb, V, Cr, Ni, and Mo to enhance strength while maintaining weldability . This grade is typically supplied in normalized or TMCP conditions and is used for critical components in large vessels and offshore platforms .

Both LR AH40 and LR AH46 are LR-certified high-strength marine steels with impact toughness tested at 0°C , ensuring reliable performance in general marine environments . Their primary difference lies in strength level: AH40 offers a minimum yield strength of 390 MPa with tensile strength of 510-650 MPa, suitable for general high-strength hull construction, while AH46 provides a higher minimum yield strength of 460 MPa with tensile strength reaching 570-720 MPa, designed for more demanding load-bearing applications requiring superior strength-to-weight ratio . Both grades feature controlled chemical composition and maintain good weldability for critical marine service, though AH46 typically requires more precise processing to achieve its enhanced mechanical properties.

Chemical Composition

Mechanical Property