S690Q is a high-strength, quenched and tempered structural steel grade that is part of the S690 series, known for its excellent combination of high yield and tensile strength, good toughness, and weldability. It is commonly used in heavy-duty applications such as large lifting equipment, high-rise building structures, offshore platforms, and mining machinery, where reliable performance under heavy loads and harsh conditions is required. The steel achieves its properties through a controlled quenching and tempering process, which refines the microstructure and ensures consistent mechanical characteristics across the thickness of the material.
S690QChemical Composition | ||||||||
Grade | The Element Max (%) | |||||||
C | Si | Mn | P | S | N | B | Cr | |
S690 Q | 0.20 | 0.80 | 1.70 | 0.020-0.025 | 0.010-0.015 | 0.015 | 0.005 | 1.50 |
Cu | Mo | Nb | Ni | Ti | V | Zr |
| |
0.50 | 0.70 | 0.06 | 2.0 | 0.05 | 0.12 | 0.15 |
| |
Grade | S690Q Mechanical Property | |||||
Thickness | Yield | Tensile | Elongation | Min Impact Energy
| ||
S690 Q | mm | Min Mpa | Mpa | Min % | -20 | 30J |
3<t≦50 | 690 | 770-940 | 14 | -20 | 30J | |
50<t≦100 | 650 | 760-930 | 14 | -20 | 30J | |
100<t≦150 | 630 | 710-900 | 14 | -20 | 30J | |
Equivalent steel grade of S690Q | |||
Europe | Germany | France | Sweden |
| StE690V | - | 2624 |
processing
1. Primary Manufacturing Processes
Heat Treatment (Q+T): The defining process involves heating the steel to its austenitizing temperature (900–960°C), followed by rapid water quenching to form a hard martensitic structure. It is then tempered (typically around 600°C) to restore ductility and toughness.
Microstructure: Processing is designed to achieve a tempered martensite or lower bainite microstructure, which provides superior load-bearing capacity compared to normalized steels.
2. Fabrication and Machining
Thermal Cutting: S690Q can be processed via flame, plasma, or laser cutting. For plates exceeding 50mm, preheating to approximately 75°C is recommended to prevent edge cracking.
Cold Forming: The material is suitable for bending if the radius is at least 3–4 times the plate thickness. Note that it requires roughly three times the power used for standard carbon steel.
Hot Forming: Should generally be avoided above 560–580°C, as it can alter the original tempering and degrade mechanical properties.
3. Welding Requirements
Preheating: Necessary for thicker plates to reduce cooling rates and prevent hydrogen-induced cold cracking.
Heat Input: Must be strictly controlled (typically between 1.25–1.58 kJ/mm). Excessive heat input can create a "soft zone" in the Heat-Affected Zone (HAZ), significantly reducing the joint's tensile strength.
Consumables: Low-hydrogen electrodes and MIG welding are common; filler materials should match or be slightly lower in strength than the base metal to mitigate cracking risks.
applications
• Heavy lifting equipment:
S690Q is commonly used in the manufacturing of cranes, mobile lifting platforms, and hydraulic lifting arms. Its high yield strength allows for the design of lighter, more efficient structures without compromising load‑bearing capacity, making it ideal for equipment that needs to handle heavy weights while maintaining maneuverability.
• High‑rise and large‑span buildings:
In the construction industry, S690Q is used for critical structural components such as columns, beams, and trusses in high‑rise buildings and large‑span structures. Its ability to withstand extreme loads and resist deformation helps enhance the overall stability and safety of modern buildings, especially in seismic‑prone regions.
• Offshore and marine structures:
Due to its good toughness and resistance to harsh environmental conditions, S690Q is employed in offshore platforms, support structures, and marine equipment. It provides reliable performance under high stress and corrosive marine environments, contributing to the structural integrity of offshore installations.
• Mining and construction machinery:
S690Q is used in the production of heavy machinery such as excavator booms, bulldozer blades, and mining truck components. Its combination of strength and toughness helps these machines withstand the abrasive and high‑impact conditions typical of mining and construction sites.
• Bridge structures:
For bridges that require high load capacity and long‑term durability, S690Q is used in critical parts such as bridge girders and support members. Its high strength allows for reduced material thickness, leading to more economical and efficient designs.
advantages
• High strength:
With a minimum yield strength of around 690 MPa, S690Q provides exceptional load‑bearing capacity, allowing designers to reduce material thickness and overall weight while maintaining structural integrity. This leads to more efficient and cost‑effective designs.
• Excellent toughness:
The steel maintains good toughness even at low temperatures, thanks to its quenched and tempered microstructure. This makes it suitable for applications exposed to harsh environments or dynamic loading conditions.
• Good weldability:
Despite its high strength, S690Q can be welded using standard techniques with proper preheating and interpass temperature control. This simplifies fabrication and reduces production time and costs.
• Improved durability:
The steel's refined microstructure and uniform properties across thickness enhance its resistance to fatigue, wear, and deformation, ensuring long‑term performance in demanding applications.
• Design flexibility:
Its high strength‑to‑weight ratio gives engineers greater flexibility in designing structures and equipment, enabling innovations in areas such as heavy machinery, high‑rise buildings, and offshore platforms.
If you have project requirements for S690Q , 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.
What is the impact energy requirement for S690Q?
S690Q requires a minimum impact energy of 30 J at -20°C (Charpy V-notch test), ensuring toughness under dynamic loads.
Can S690Q be used in offshore structures?
Yes, S690Q is suitable for offshore structures like platforms and jackets, as it resists high loads and harsh marine environments with proper protection.
What is the difference between S690Q and S460Q?
S690Q has a higher yield strength (690 MPa vs. 460 MPa for S460Q) and is used for more demanding, heavy-load applications.
How to store S690Q plates to prevent corrosion?
Store S690Q plates in a dry, well-ventilated area, away from moisture and chemicals. Cover with waterproof sheets to avoid rusting.
Can S690Q be nitrided?
Yes, S690Q can be nitrided to improve surface hardness and wear resistance. This process enhances its performance in wear-prone applications.
What is the elongation at break of S690Q?
The minimum elongation at break of S690Q is 14% (for 16 mm thickness). It ensures sufficient ductility for structural safety.
Is S690Q suitable for crane booms?
Yes, S690Q is ideal for crane booms. Its high strength reduces weight while maintaining load-bearing capacity, improving crane efficiency.
What are the inspection methods for S690Q?
Common inspection methods include tensile testing, impact testing, hardness testing, ultrasonic testing, and visual inspection to ensure quality.