S690QL is a high-strength quenched and tempered structural steel, renowned for its balanced performance, which endows it with favorable processability, wide-ranging applications, and remarkable advantages in engineering projects.
| Typical chemical composition of S690QL % Max | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
C |
SI |
Mn |
P |
S |
N |
B | Cr | Cu | Mo | Nb | Ni | Ti | V | Zr |
| 0.2 | 0.80 | 1.70 | 0.025 | 0.015 | 0.015 | 0.005 | 1.50 | 0.50 | 0.70 | 0.06 | 2.0 | 0.05 | 0.12 | 0.15 |
| Mechanical Properties of S690QL | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Designation | Mechanical Properties (ambient temperature) | ||||||||||
| Steel Name | Steel Number | Min. Yield Strength ReH MPa | Tensile Strength Rm MPa | Min. & elongation after fracture | |||||||
| Nominal thickness (mm) | Nominal thickness (mm) | ||||||||||
| >3 <50 | >50 <100 | >100 <150 | >3 <50 | >50 <100 | >100 <150 | ||||||
| S690QL | 1.8931 | 690 | 650 | 630 | 770/940 | 760/930 | 710/900 | 14 | |||
| V notch impact testing | |||||
|---|---|---|---|---|---|
|
Grade |
Sample Orientation |
at 0°C |
at -20°C |
at -40°C |
at -60°C |
| S690QL | Longitudinal | 50J | 40J | 30J | |
| S690QL | Transverse | 35J | 30J | 27J | |
Core Processing Techniques
Cutting: S690QL plates can be cut using advanced technologies like CNC plasma, laser, or oxy-fuel. For thermal cutting, it is recommended to keep the material at least at room temperature to prevent issues.
Bending and Forming:
Cold Forming: Possible with powerful equipment. Recommended inside bend radii are typically >4×thickness for longitudinal and >3×thickness for transverse directions.
Hot Forming: Generally avoided above 580°C–600°C as it can alter the tempered state and degrade mechanical properties. If heated above this range, the material must undergo a new quenching and tempering process.
Welding: S690QL has good weldability but is sensitive to cooling rates.
Methods: MIG/MAG and TIG are commonly used.
Precautions: Pre-heating is often required to avoid cold cracking. Filler metals should have similar or slightly lower strength than the base metal.
Machining: For drilling, cobalt-alloyed high-speed steels (HSSCO) are recommended with a cutting speed of 17–19 m/min.
Production Workflow
The industrial production of S690QL involves a complex sequence to ensure its high-strength properties:
Refining & Casting: Converter refining followed by continuous casting.
Rolling: Controlled rolling and cooling to achieve the initial plate structure.
Heat Treatment (Q+T): The defining step where the plate is quenched (rapidly cooled in water from above its critical temperature) to harden it, followed by tempering (re-heating to below the critical point) to restore toughness and ductility.
Finishing: Straightening, surface inspection, and ultrasonic flaw detection.
Main Applications
Its applications span multiple heavy-duty industries, mainly including:
Construction industry: Widely used in large-scale structures such as bridge supports, crane booms, and high-rise building frameworks, where high load-bearing capacity and light weight are critical requirements.
Automotive and transportation sector: Applied to truck frames, trailer components, and railway vehicle parts, it enhances product durability while reducing overall weight to improve fuel efficiency.
Offshore and mining fields: Essential for offshore platforms and mining machinery components, as it can withstand harsh environments like corrosion and low temperatures.
If you have project requirements for S690QL, we welcome your inquiry. GNEE maintains a large inventory of commonly used high strength steel grades for your selection.For detailed mechanical properties, chemical composition, and technical data, as well as free samples, please contact our factory immediately. We offer competitive prices, stable quality, and professional service. Email:beam@gneesteelgroup.com.
Can S690QL be welded easily?
Yes, S690QL has good weldability. Proper preheating and post-weld heat treatment are recommended to avoid cold cracks and ensure weld joint integrity.
What is the typical application of S690QL?
It is commonly used in cranes, excavators, bridge structures, offshore platforms and mining equipment due to its high strength and durability.
What is the hardness range of S690QL?
The hardness range of S690QL is usually 210-260 HBW. This hardness balances strength and machinability for various engineering uses.
Is S690QL corrosion-resistant?
S690QL has moderate corrosion resistance. For harsh environments, additional protection like painting, galvanizing or coating is required.
What is the maximum thickness of S690QL available?
S690QL is available in thicknesses up to 200 mm. Thicker plates are suitable for heavy-duty structures requiring high load-bearing capacity.
What is the difference between S690QL and S690Q?
S690QL has better toughness than S690Q. The "L" indicates improved low-temperature impact performance, suitable for colder environments.
Can S690QL be bent?
Yes, S690QL can be bent, but larger bend radii are needed compared to mild steel. Preheating may be required for thick sections to avoid cracking.
What is the density of S690QL?
The density of S690QL is approximately 7.85 g/cm³, the same as most carbon and low-alloy steels, facilitating weight calculation in designs.
Is S690QL magnetic?
Yes, S690QL is ferromagnetic due to its iron-based composition. This property is irrelevant for most structural applications but should be noted in magnetic environments.
What is the weight of a 10mm thick S690QL plate per square meter?
A 10mm thick S690QL plate weighs about 78.5 kg per square meter, calculated by density × thickness × area.
Is S690QL a low-alloy steel?
Yes, S690QL is a low-alloy high-strength steel. It contains small amounts of alloying elements to improve strength without sacrificing weldability.