What are the properties of S690Q steel?
S690Q steel is a high-strength, fine-grain structural steel (HSLA) that's quenched and tempered (Q) for exceptional strength (minimum 690 MPa yield) and toughness, used in heavy-duty applications like bridges, cranes, and machinery where weight savings and high load capacity are critical, conforming to EN 10025-6 standards. Its designation breaks down as 'S' (Structural), '690' (min yield strength in MPa), and 'Q' (Quenched & Tempered).
Key Characteristics
High Strength: Minimum yield strength of 690 MPa, with typical tensile strength between 770-940 MPa, providing excellent load-bearing capacity.
Toughness: Good impact toughness, often guaranteed at temperatures down to -20°C.
Fine Grain: Achieved through heat treatment, contributing to its strength and toughness.
Weldability: Considered to have good weldability for its strength class, though proper procedures like preheating are usually needed, especially for thicker plates.
Low Alloy: A controlled chemical composition that supports its high performance.
Applications
Heavy construction equipment (excavators, loaders)
Bridges and offshore structures (drilling rigs, windmill supports)
Cranes and lifting equipment
Pressure vessels
High-load structural elements in various machinery
Designation Breakdown
S: Structural Steel
690: Minimum Yield Strength (690 MPa)
Q: Quenched and Tempered (heat treatment condition)
What are the properties of S690Q steel?
1. High Strength: It has a minimum yield strength of 690 MPa and a typical tensile strength range of 770-940 MPa. This makes it over twice as strong as common structural steel (like S355).
2. Good Toughness: As a quenched and tempered (Q) grade, it offers excellent impact toughness, especially at low temperatures. Sub-grades like S690QL specify even higher toughness at -40°C or -60°C.
3. Good Weldability: Despite its high strength, it is designed to be weldable. This requires careful procedure (using low-hydrogen electrodes, preheating, and controlled heat input) to preserve its properties in the heat-affected zone.
4. Hardness: It has a high hardness, typically in the range of 240-300 HBW (Brinell Hardness).
5. Ductility: It maintains a reasonable level of ductility, with a minimum elongation at break of around 14%, allowing for some deformation before failure.
6. Fatigue Resistance: It exhibits good fatigue strength, making it suitable for dynamic and load-bearing structures like cranes and transport equipment.
Key Takeaway: S690Q is a high-strength, low-alloy (HSLA) steel that achieves its exceptional balance of strength and toughness through the quenching and tempering heat treatment process. It is primarily chosen where reducing weight and material thickness is critical without compromising structural integrity.
Technical data
EN10025-6 S690Q quenched and tempered steel plate Chemical composition
| Grade | C % | Si % | Mn % | P % | S % | N % | B % | Cr % |
| S690Q | 0.200 | 0.800 | 1.700 | 0.025 | 0.015 | 0.015 | 0.005 | 1.500 |
| Cu % | Mo % | Nb % | Ni % | Ti % | V % | Zr % | ||
| 0.500 | 0.700 | 0.060 | 2.000 | 0.050 | 0.120 | 0.150 |
EN10025-6 S690Q quenched and tempered steel plate mechanical properties
| Grade | Thickness | Min Yield | Tensile | Elongation | Min Impact Energy | |
| S690Q | 8mm-50mm | Min 690Mpa | 770-940Mpa | 14% | -20 | Min 30J |
| 51mm-100mm | Min 650Mpa | 760-930Mpa | 14% | -20 | Min 30J | |
| 101mm-150mm | Min 630Mpa | 710-900Mpa | 14% | -20 | Min 30J |
What is S690Q steel?
S690Q is a high-strength quenched and tempered structural steel grade with a minimum yield strength of 690 MPa, often used in demanding construction and lifting applications.
What are the properties of S690Q steel?
S690Q offers high strength, good toughness at low temperatures, and excellent weldability due to its quenched and tempered microstructure.
What is the difference between S690QL and S690Q?
S690QL is a sub-grade with specified low-temperature impact toughness, while S690Q is the base grade; both share the same minimum yield strength.
Where is S690Q steel used?
It is commonly used in heavy machinery, mobile cranes, mining equipment, and advanced structural components where high strength-to-weight ratio is critical.
How to weld S690Q steel?
Welding S690Q typically requires low-hydrogen electrodes, preheating, and controlled heat input to maintain its mechanical properties and prevent cracking.
What is the chemical composition of S690Q?
S690Q contains elements like carbon, manganese, silicon, and micro-alloys such as niobium, vanadium, and titanium, with precise limits to ensure its properties.
Is S690Q steel corrosion resistant?
No, S690Q is not inherently corrosion-resistant; it requires protective coatings or paints for use in corrosive environments.
What are the machining guidelines for S690Q?
Machining S690Q requires robust tools, adequate cooling, and slower speeds due to its high strength and hardness.
What is the price of S690Q steel plate?
The price of S690Q varies based on thickness, quantity, and market factors, but it is generally more expensive than standard structural steels due to its advanced processing.
Full specification and details are available on request. The above information is provided for guidance purposes only. For specific design requirements please contact our technical sales staff.
