Difference between LR EH50 and LR EH62 steel plate

LR EH50 and LR EH62 are ultra-high-strength shipbuilding steel plates certified by Lloyd's Register (LR). As part of the "EH" (Extra High-strength, High toughness) series, they are engineered for the most demanding maritime and offshore applications. These grades are typically used in critical, highly stressed areas of very large container ships (such as hatch coamings and upper deck structures), heavy-lift vessels, and specialized Arctic-class vessels, where maximizing strength-to-weight ratio while maintaining outstanding low-temperature toughness and weldability is essential.

Key Differences:

The primary distinction is their specified minimum yield strength. LR EH50 has a yield strength of 390 MPa (the '50' denotes a minimum tensile strength of 500 MPa or 50 kgf/mm²), while LR EH62 offers a significantly higher yield strength of 460 MPa (with a minimum tensile strength of 620 MPa). This makes EH62 one of the strongest grades in commercial shipbuilding, enabling the greatest potential for weight savings and payload optimization.

Achieving this ultra-high strength without compromising toughness requires a more advanced metallurgical design. EH62 typically has a higher alloy content (e.g., Niobium, Vanadium, Nickel) and is produced under strict TMCP conditions. This results in a notably higher carbon equivalent (Ceq) and Pcm value for EH62 compared to EH50. Consequently, fabrication-especially welding-of EH62 is considerably more challenging. It demands the strictest procedures: specific low-hydrogen consumables, precise control of preheating and interpass temperatures, stringent control of heat input, and often mandatory post-weld heat treatment to prevent hydrogen-induced cracking and preserve the mechanical properties of the weld zone. The choice between these grades is a critical decision, balancing the need for maximum structural efficiency (EH62) against significantly increased material cost and fabrication complexity (EH50).

Chemical Composition

Mechanical Property