S960QL is a high-yield, high-strength structural steel grade produced in accordance with the EN 10025-6 standard. It is a quenched and tempered (Q&T) material, which provides it with exceptional strength-to-weight ratios and abrasion resistance.
Key Specifications & Properties
Yield Strength: Minimum of 960 MPa.
Numerical Designation: 1.8933.
Heat Treatment: Quenched and tempered (Q) to achieve a fine-grained martensite–bainite microstructure.
Impact Toughness: The "L" in its name signifies low-temperature impact testing, typically at -40°C, with impact energy values usually around 40J.
Weldability: It has good weldability but is sensitive to excessive heat input, which can reduce its local strength (HAZ) or affect the microstructure.
Chemical Composition of S960QL
| % | |
|---|---|
| C | 0.20 |
| Si | 0.80 |
| Mn | 1.70 |
| P | 0.020 |
| S | 0.010 |
| N | 0.015 |
| B | 0.0050 |
| Cr | 1.50 |
| Cu | 0.50 |
| Mo | 0.70 |
| Nb | 0.06 |
| Ni | 2.0 |
| Ti | 0.05 |
| V | 0.12 |
| Zr | 0.15 |
Applications
Due to its high strength and durability, S960QL is primarily used in industries requiring high payloads and weight reduction. Its excellent strength-to-weight ratio allows engineers to design lighter structures without sacrificing performance, making it suitable for a wide range of demanding applications.
• Heavy Transport
S960QL is widely used in the manufacturing of truck and trailer chassis and frames. By using this high-strength steel, manufacturers can reduce the thickness of structural parts while maintaining or even increasing load capacity. This results in lighter vehicles that can carry heavier cargo, improve fuel efficiency, and reduce operational costs. The material's toughness also helps absorb impact and vibration, enhancing overall durability and safety during long-haul transportation.
• Lifting Equipment
In the lifting equipment industry, S960QL is a preferred material for mobile crane booms, telescopic arms, and masts. Its high yield strength and good fatigue resistance enable the construction of longer, lighter booms that can handle heavy loads with improved stability. The reduced weight of the boom also allows cranes to operate with greater flexibility and maneuverability, especially in confined spaces. Additionally, the steel's toughness at low temperatures ensures reliable performance even in cold working environments.
• Mining & Earthmoving
S960QL is used in excavator buckets, load-bearing elements, and various structural components in mining and earthmoving equipment. The material's combination of high strength and wear resistance makes it ideal for withstanding the abrasive conditions of mining sites, where equipment is exposed to heavy impacts, constant loading, and harsh terrain. By using S960QL, manufacturers can extend the service life of components and reduce maintenance requirements, leading to lower downtime and increased productivity.
• Civil Engineering
In civil engineering, S960QL is employed in bridge structures and high-rise building components. Its ability to withstand extreme loads and resist fatigue makes it suitable for critical structural parts such as beams, columns, and trusses. The steel's consistent mechanical properties and good weldability also simplify fabrication and construction processes, ensuring the structural integrity and long-term durability of large-scale infrastructure projects.
processing steps
1. Cutting
Thermal Cutting: S960QL is suitable for laser, plasma, and oxy-fuel cutting.
Laser cutting is preferred for high-precision components and a fine surface finish.
Pre-processing: Plates should be warmed to approximately +20°C before cutting to prevent cold cracking.
Mechanical Cutting: Best performed with heavy-duty guillotine shears. Sharp blades and correct clearance settings are critical due to the material's extreme hardness.
2. Welding
Welding is the most critical processing step, as excessive heat can degrade the tempered microstructure.
Low Hydrogen Process: Use MIG/MAG (with M21 shielding gas) or TIG welding. Consumables must have low hydrogen content to prevent hydrogen-induced cold cracking.
Heat Input Control: Maintain a specific cooling time (t8/5) between 800°C and 500°C. For 2026 standards, using software like WeldCalc is recommended to calculate allowable heat intervals.
Preheating: Necessary for thicker plates to reduce the cooling rate and minimize residual stress.
3. Forming and Bending
Bending: Can be cold-formed, but requires significantly higher bending forces than standard structural steel.
Springback: Expect substantial springback; over-bending is usually required to achieve the desired final angle.
Surface Preparation: Ensure the plate surface is clean and free of grinding marks in the bending zone to avoid crack initiation.
4. Machining (Milling & Drilling)
S960QL is considered difficult to machine due to its high strength.
Parameters: Research for 2026 suggests optimum milling parameters include a cutting speed of ~110 m/min and a low feed rate of ~0.08 mm/tooth to manage cutting force and temperature.
Tooling: Use high-quality, carbide-coated tools. Rigid machine setups are essential to avoid vibration and chatter.
5. Heat Treatment
Quenching & Tempering: Primarily performed by the manufacturer to create the fine-grained martensite–bainite structure.
Post-Weld Heat Treatment (PWHT): Generally avoided as it can reduce the yield strength. If mandatory for stress relief, it must be performed at temperatures below the original tempering temperature (typically < 580°C).
Get an valued quotation for S960QL, Contact GNEE Steel.
What is the minimum yield strength of S960QL?
The minimum yield strength of S960QL is 960 megapascals (MPa). This high yield strength makes it suitable for applications requiring heavy load resistance, ensuring structural stability in demanding engineering projects like crane booms and bridge components.
What is the modulus of elasticity of S960QL?
Its modulus of elasticity is approximately 206 GPa, same as most structural steels. This value is used in structural design calculations to predict deformation under load, ensuring structural stability and precision.
Does S960QL have a fatigue limit?
Yes, S960QL has a fatigue limit of around 400-450 MPa (for 10⁷ cycles). Fatigue resistance is critical for dynamic load applications like machinery parts, requiring proper design to avoid cyclic stress-induced failure.
What is the maximum operating temperature of S960QL?
The maximum safe operating temperature of S960QL is 300°C. Beyond this, its mechanical strength decreases significantly. For high-temperature applications, consider heat-resistant alloy steels instead.
Does S960QL require preheating before welding?
Yes, preheating is necessary for S960QL welding. The recommended preheating temperature is 80-150°C, depending on thickness. Preheating reduces the cooling rate, preventing martensite formation and cold cracking in the weld zone.
What is the thermal conductivity of S960QL?
The thermal conductivity of S960QL is about 45 W/(m·K) at room temperature. This property affects welding and heat treatment processes, requiring controlled heating/cooling rates to avoid thermal stress and material damage.
What is the typical application of S960QL?
S960QL is commonly used in heavy-duty equipment: crane booms, mining machinery, offshore platforms, and high-rise building steel structures. It also fits in military vehicles and pressure vessels requiring high strength-to-weight ratio.
Can S960QL be used in low-temperature environments?
Yes, it can. With good low-temperature toughness (≥40 J at -20°C), S960QL is suitable for cold regions. For lower temperatures (-40°C), check manufacturer's data sheets for modified grades to ensure fracture resistance.
Can S960QL be machined easily?
Machining S960QL is challenging due to high strength. Use high-speed steel or carbide tools with sharp cutting edges. Reduce cutting speed, increase feed rate moderately, and use cutting fluids to improve tool life and surface finish.
What is the density of S960QL?
The density of S960QL is approximately 7.85 g/cm³, same as conventional carbon steels. This allows accurate weight calculation for structural design, ensuring optimal strength-to-weight ratio in engineering projects.
Is S960QL weldable?
Yes, S960QL is weldable, but proper procedures are required. Preheating and post-weld heat treatment (PWHT) are recommended to prevent cold cracking. Use low-hydrogen welding consumables to maintain its mechanical properties after welding.