Difference between LR AH62 and LR AH69 steel plate

LR AH62 is an ultra-high-strength marine steel plate certified by Lloyd's Register (LR) for demanding shipbuilding and offshore 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% . The chemical composition features carbon ≤0.21%, manganese ≤1.70%, and additional alloying elements including nickel (0.70-1.80%), chromium (0.40-1.60%), and molybdenum (≤0.70%) to achieve superior mechanical properties . Impact toughness is tested at 0°C, requiring minimum 41J (transverse) and 62J (longitudinal) . This grade is delivered in normalized or quenched and tempered (QT) conditions .

LR AH69 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 690 MPa and tensile strength ranging from 770 to 940 MPa, with a minimum elongation of 16% . The chemical composition features carbon ≤0.21% and manganese ≤1.70%, with microalloying elements such as Nb, V, Ti, Cr, Ni, and Mo . Impact toughness is tested at -60°C, requiring minimum 46J (transverse) and 69J (longitudinal) . This grade is delivered in normalized, quenched and tempered (QT), or TMCP conditions .

Both LR AH62 and LR AH69 are LR-certified ultra-high-strength marine steels designed for demanding shipbuilding and offshore applications. Their primary differences lie in strength level and low-temperature performance: AH62 offers a minimum yield strength of 620 MPa with impact testing at 0°C, suitable for critically stressed structural components requiring high strength-to-weight ratio, while AH69 provides a substantially higher minimum yield strength of 690 MPa with superior low-temperature toughness tested at -60°C, designed for the most demanding load-bearing applications in extreme environments such as Arctic offshore platforms . Both grades feature strictly controlled chemical composition and require advanced processing like QT or TMCP to achieve their enhanced mechanical properties while maintaining good weldability for critical marine service .

Chemical Composition

Mechanical Property