Difference between S460QL1 and S500QL1

S460QL1 and S500QL1 are high-strength, quenched and tempered structural steel plates manufactured to the European standard EN 10025-6. The "QL1" suffix specifies their delivery condition: Quenched (Q) and Tempered (T) with guaranteed impact toughness tested longitudinally (L1) at low temperatures (typically -40°C or -60°C). These grades are designed for critical structural components that demand an optimal combination of high strength, excellent low-temperature toughness, and weldability, such as in offshore structures, heavy-duty mobile cranes, mining equipment, and high-performance transportation vehicles.

Key Differences:

The core distinction is their strength level. S460QL1 offers a minimum yield strength of 460 MPa, while S500QL1 provides a higher yield strength of 500 MPa. This makes S500QL1 capable of withstanding greater static loads, allowing for potential weight reduction or increased safety margins in design.

To achieve this higher strength while maintaining the stringent "QL1" toughness requirements, S500QL1 requires a more refined chemical composition and precise control during the quenching and tempering process. It typically involves optimized additions of micro-alloying elements (like Niobium and Vanadium) and carefully balanced levels of carbon and manganese. Consequently, S500QL1 generally has a slightly higher carbon equivalent (Ceq) compared to S460QL1. This results in more demanding fabrication requirements for S500QL1. Welding, in particular, necessitates stricter procedural controls: the mandatory use of qualified low-hydrogen consumables, precise management of preheat and interpass temperatures, careful limitation of heat input, and often post-weld heat treatment (PWHT) for thick sections to prevent hydrogen-induced cracking and preserve the toughness in the weld heat-affected zone.

Chemical Composition

Mechanical Property