LR Rules Part 3 — LR Marine Structural Steel Specification
Grades
普通强度: A, B, D, E; 高强度: AH32, DH32, EH32, FH32, AH36, DH36, EH36, FH36, AH40, DH40, EH40, FH40
Chemical composition and mechanical properties
| Grade | Chemical composition | Mechanical properties |
|---|---|---|
| D | C≤0.21, Mn≥0.60(>25mm), P≤0.035, S≤0.035 | Rm 400-520 MPa, Rp0.2 ≥235 MPa, A≥22%, quenching and tempering |
| E | C≤0.18, Mn≥0.70, P≤0.035, S≤0.035, Al≥0.015 | Rm 400-520 MPa, Rp0.2 ≥235 MPa, A≥22%, Akv≥27J at -40℃, quenching and tempering |
| AH32 | C≤0.18, Mn 0.70-1.60, Si 0.10-0.50, P≤0.030, S≤0.030, Nb 0.005-0.05, V 0.02-0.10, Ti≤0.02, Cu≤0.35, Cr≤0.20, Ni≤0.40, Mo≤0.08, N≤0.012 | Rm 440-590 MPa, Rp0.2 ≥315 MPa, A≥22%, Akv≥31J at 0℃, TMCP/normalizing |
Application scope
LR Rules Part 3 is a shipbuilding specification issued by Lloyd's Register of Shipping in the UK. It specifies the requirements for structural steel plates used in ships, including grades A, B, D, and E for ordinary strength and AH to FH for high strength. The specification stipulates requirements for composition, tensile strength, and low-temperature impact, emphasizing good weldability and low-temperature toughness. Deliveries must be approved by the relevant classification society or system, and it applies to the load-bearing structures of ships.
Typical applications
Widely used in the hull structure, decks, and bulkheads of LR-classed bulk carriers, tankers, container ships, and other load-bearing components. The standard strength grade is used for conventional hulls, while the high strength grade is used in high-stress and weight-reduction areas. With its good weldability and low-temperature toughness, it is suitable for various ocean-going and coastal vessel structures that primarily rely on welded assembly and must meet Lloyd's Register classification requirements.
