S960QL is a high-strength quenched and tempered structural steel grade within the European standard series for heavy-duty applications. It is characterized by a very high yield strength combined with good toughness, even at low temperatures, which makes it suitable for highly stressed structures where weight reduction and structural efficiency are important. The steel achieves its properties through a thermomechanical rolling process followed by quenching and tempering, resulting in a fine-grained microstructure with a balance of strength and ductility. Typical applications include heavy lifting equipment, mobile crane booms, offshore structures, and high-performance load-bearing components in the engineering and construction machinery sectors.
Chemical composition
| C | Si | Mn | Ni | P | S | Cr | Mo | V | N | Nb | Ti | Cu | Zr | B | CEV |
| max 0.2 | max 0.8 | max 1.7 | max 2 | max 0.02 | max 0.01 | max 1.5 | max 0.7 | max 0.12 | max 0.015 | max 0.06 | max 0.05 | max 0.5 | max 0.15 | max 0.005 | max 0.82 |
Mechanical properties
| Nominal thickness (mm): | 3 - 50 |
| Rm - Tensile strength (MPa) | 980-1150 |
| Nominal thickness (mm): | 3 - 50 |
| ReH - Minimum yield strength (MPa) | 960 |
| KV - Impact energy (J) longitud., | 0° 50 |
-20° 40 |
-40° 30 |
| A - Min. elongation Lo = 5,65 √ So (%) | 10 |
Applications
Heavy Lifting & Transportation:
Extensively used for mobile crane booms, crawler cranes, truck chassis, and trailers. Its high strength (960 MPa yield) allows for lighter designs, increasing payload capacity and fuel efficiency.
Mining & Earthmoving:
Essential for heavy-duty mining trucks (over 100-ton capacity), excavators, dump truck bodies, and coal mine hydraulic supports.
Military Engineering:
Utilized in the construction of armored vehicles, naval vessel structural components, and weapon systems (e.g., missile structures and firearm parts) due to its durability in high-stress environments.
Civil Engineering & Infrastructure:
Applied in high-rise buildings, fabricated bridge towers, and large-scale industrial plants. It is particularly valuable for structures in cold or harsh climates, such as offshore platforms, where it maintains impact toughness down to -40°C.
Energy Sector:
Used in the fabrication of wind turbine towers, penstocks (water intake pipes), and unfired pressure vessels.
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What is S960QL?
S960QL is a high-strength quenched and tempered structural steel grade specified in European standards. It is known for its very high yield strength combined with good toughness, even at low temperatures, making it suitable for heavily loaded structures where weight reduction is also a priority.
What does the designation "S960QL" mean?
In the designation "S960QL", the letter S stands for structural steel, the number indicates the minimum yield strength level, Q denotes quenched and tempered, and L signifies improved toughness at lower temperatures compared to basic grades.
What standards cover S960QL?
S960QL is covered by the European standard for high-strength structural steels, specifically the part dealing with quenched and tempered fine-grained steels. This standard specifies the technical delivery conditions, including chemical composition, mechanical properties, and testing requirements.
What are the typical mechanical properties of S960QL?
S960QL is characterized by a very high yield strength, a high tensile strength, and good ductility. It also has specified impact toughness values at low temperatures, which means it can absorb energy without brittle fracture even in cold environments.
What is the typical chemical composition of S960QL?
S960QL generally has a low carbon content to maintain weldability and toughness, balanced amounts of manganese, and additions of alloying elements such as chromium, nickel, molybdenum, and sometimes vanadium or niobium. These elements help to achieve high strength while preserving good toughness and microstructure stability.
What is the microstructure of S960QL?
After quenching and tempering, S960QL typically has a fine-grained microstructure, often consisting mainly of tempered martensite or a mixture of tempered martensite and bainite. This microstructure provides the combination of high strength and good toughness required for demanding applications.
What is the typical delivery condition of S960QL?
S960QL is usually delivered in the quenched and tempered condition. This involves heating the steel to a suitable temperature, quenching in water or oil to form a hard microstructure, and then tempering at a lower temperature to reduce hardness slightly while improving toughness and ductility.
What thicknesses is S960QL available in?
S960QL is produced in a range of thicknesses, from relatively thin plates up to thicker sections. As thickness increases, the achievable strength and toughness may be slightly reduced, so producers often apply stricter controls and additional alloying for thicker plates.
What are the main applications of S960QL?
S960QL is commonly used in heavy lifting equipment, such as mobile crane booms and telescopic arms, as well as in other high-performance structural components. It is also found in offshore structures, mining machinery, and parts of heavy trucks and construction equipment where high strength and low weight are important.
Why is S960QL used for crane booms?
S960QL is used for crane booms because its high strength allows the design of lighter and more slender structures while maintaining the required load-carrying capacity. This reduces the overall weight of the crane, improves mobility, and increases lifting performance.