Difference between LR AH46 and LR AH62 steel plate

LR AH46 is an extra-high-strength marine steel plate certified by Lloyd's Register (LR) for shipbuilding and offshore applications. It 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 is strictly controlled with carbon ≤0.21% and manganese ≤1.70% . This grade is typically supplied in normalized (N), thermomechanical controlled rolled (TM), or quenched and tempered (QT) conditions . Impact toughness is tested at 0°C, with minimum impact energy of 31J (transverse) and 46J (longitudinal) .

LR AH62 is an ultra-high-strength marine steel plate also certified by Lloyd's Register (LR), designed for the most demanding structural applications. It has a minimum yield strength of 620 MPa and tensile strength ranging from 720 to 890 MPa, with a minimum elongation of 17% . To achieve its superior mechanical properties, its chemical composition includes a lower carbon content (≤0.18%) and the addition of microalloying elements such as nickel (0.70-1.80%), chromium (0.40-1.60%), and molybdenum (≤0.70%) . This grade is delivered in normalized or quenched and tempered (QT) conditions . Impact toughness is tested at 0°C, with minimum impact energy of 41J (transverse) and 62J (longitudinal) .

Both LR AH46 and LR AH62 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: AH46 offers a minimum yield strength of 460 MPa, suitable for extra-high-strength hull construction and offshore structures, while AH62 provides a substantially higher minimum yield strength of 620 MPa, designed for the most demanding load-bearing applications requiring maximum strength-to-weight ratio. Consequently, AH62 employs a more complex alloying design (with Ni, Cr, Mo additions) and advanced processing methods such as QT compared to AH46 to achieve its enhanced properties, while both grades maintain good weldability for critical marine service. The selection between them depends on whether the project requires the balanced strength of AH46 or the superior performance of AH62 for more extreme structural demands.

Chemical Composition

Mechanical Property