S460QL is a quenched and tempered high-strength structural steel defined in EN 10025-6, the European standard for hot-rolled quenched and tempered high-yield-strength structural steels. It is valued for its combination of high strength and excellent low-temperature toughness, which makes it a key material for heavy-load and low-temperature structures.
Grade Meaning and Standard
Each part of the designation has a clear meaning:
S: structural steel.
460: minimum yield strength of 460 MPa for plates up to 50 mm thick.
Q: quenched and tempered delivery condition.
L: improved low-temperature toughness, verified by Charpy V-notch impact testing at -40 deg C.
The grade corresponds in strength level to the Chinese Q460E high-strength structural steel in GB/T 1591. The two designations are similar in yield class, but they follow different standards with differences in inspection details, so substitution requires verification against the project specification.
Chemical Composition
The composition of S460QL is controlled to balance strength, weldability, and low-temperature toughness. Key limits specified in EN 10025-6 include:
| Element | Typical maximum, % |
|---|---|
| Carbon (C) | 0.20 |
| Silicon (Si) | 0.80 |
| Manganese (Mn) | 1.70 |
| Phosphorus (P) | 0.025 |
| Sulfur (S) | 0.015 |
| Nitrogen (N) | 0.015 |
| Microalloys (Nb, V, Ti) | Each limited, e.g. Nb 0.06, V 0.12, Ti 0.05 |
| Chromium, Nickel, Molybdenum, Copper | Controlled additions per the standard |
Carbon is limited to protect weldability and toughness, phosphorus and sulfur are tightly controlled to reduce brittle inclusions, and microalloying elements refine the grain structure. Exact limits depend on the edition of the standard and the plate thickness; the mill test certificate is the authoritative reference.
Mechanical Properties
Yield strength (ReH): minimum 460 MPa for thicknesses of 3-50 mm, 440 MPa for 50-100 mm, and 400 MPa for thicknesses over 100 mm.
Tensile strength (Rm): 550-720 MPa for thicknesses up to 100 mm, and 500-670 MPa above 100 mm.
Impact energy: at least 30 J at -40 deg C (longitudinal), which protects against brittle fracture in cold service.
Elongation: minimum values are specified by thickness range in the standard.
The quenched and tempered microstructure delivers the high strength-to-weight ratio that makes the grade attractive for weight-critical designs.
Delivery Condition and Heat Treatment
S460QL is delivered in the quenched and tempered condition. The heat treatment consists of austenitizing followed by quenching, then tempering to adjust the balance of strength and toughness. With the agreement of the purchaser, accelerated cooling methods may be used before tempering. The standard product range is plates from 3 mm upward; practical supply is commonly within 150 mm thickness, and thicker plates require special agreement and testing.
Optional testing that can be added to the order includes:
Z-direction testing (Z15, Z25, Z35) for through-thickness properties where lamellar tearing resistance is required in highly restrained joints.
Ultrasonic examination and other non-destructive testing for internal soundness.
Enhanced Charpy testing at temperatures below -40 deg C when required by the design code.
Applications
Mining machinery: drilling rigs, electric shovels, and mining dump truck frames.
Construction machinery: crane booms, hydraulic supports, and bulldozer structures.
Infrastructure: bridge girders, industrial platforms, and heavy equipment supports in cold regions.
Offshore and energy structures exposed to low temperatures and dynamic loads.
Frequently Asked Questions
What do the letters and numbers in S460QL mean? S means structural steel, 460 is the minimum yield strength in megapascals for plates up to 50 mm thick, Q indicates the quenched and tempered delivery condition, and L means impact testing at -40 deg C per EN 10025-6.
What is the yield strength of S460QL? The minimum yield strength is 460 MPa for plates of 3-50 mm thickness, decreasing to 440 MPa for 50-100 mm and 400 MPa above 100 mm.
How does S460QL compare with Q460E? Both are 460 MPa yield class structural steels with low-temperature impact testing. S460QL follows EN 10025-6 and Q460E follows GB/T 1591; the standards differ in inspection details and thickness-dependent values, so substitution must be verified against the design specification.
Can S460QL be welded? Yes, with a qualified welding procedure. Low-hydrogen consumables, preheat and interpass temperature control, and management of heat input are required to preserve the properties of the heat-affected zone.
What is S460QL used for? It is used for crane booms, mining machinery, bridge structures, industrial platforms, and other heavy-load or low-temperature applications where high strength and toughness are both required.
Does S460QL require special testing? The base specification requires tensile and impact testing. Additional tests such as Z-direction testing, ultrasonic examination, or lower-temperature Charpy testing can be specified when the design demands them.