S690Q is a high-strength structural steel supplied in the quenched and tempered condition, as defined in the European standard EN 10025-6. The "S" indicates structural steel, and the "Q" denotes the quenched and tempered delivery state. This grade is designed to provide a high yield strength together with good toughness, even at low temperatures. It is often microalloyed to refine the grain structure and improve mechanical properties while maintaining acceptable weldability for heavy fabrication. S690Q is widely used in applications that require a high strength-to-weight ratio, such as large lifting equipment, mobile crane structures, offshore machinery, and heavy-duty construction and mining equipment.
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 0.025 | max 0.015 | 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 0.83 |
Mechanical properties of steel S690Q
| Nominal thickness (mm): | 3 - 50 | 50 - 100 | 100 - 150 |
| Rm - Tensile strength (MPa) | 770-940 | 760-930 | 710-900 |
| Nominal thickness (mm): | 3 - 50 | 50 - 100 | 100 - 150 |
| ReH - Minimum yield strength (MPa) | 690 | 650 | 630 |
| KV - Impact energy (J) longitud., | 0° 40 |
-20° 30 |
| A - Min. elongation Lo = 5,65 √ So (%) | 14 |
applications
Construction and Lifting Machinery
It is applied to core load-bearing components of mobile cranes, such as booms, outriggers and main frames. Its high strength allows lighter, more compact designs without sacrificing load capacity, boosting equipment mobility and efficiency. It also suits telescopic arms of concrete pump trucks and aerial work platforms, withstanding repeated stress and heavy loads to ensure long-term safety.
Offshore and Marine Engineering
In harsh offshore environments, it fabricates critical structures like jack-up rig legs, offshore crane parts and platform frames. Its excellent low-temperature toughness adapts to cold conditions, while controlled chemical composition ensures good weldability for large assemblies. It also supports offshore wind power equipment, stabilizing turbines under complex marine loads.
Mining and Heavy-Duty Equipment
In mining, it makes hydraulic support columns, shearer bodies and mining truck structures. It resists intense impact, pressure and abrasion, extending component lifespan and reducing maintenance costs. It also equips heavy excavators and loaders, enabling them to handle tough mining and earth-moving tasks.
Infrastructure and Large-Span Structures
It is used in key stress-bearing parts of large-span bridges, reducing overall weight via its high strength-to-weight ratio for easier construction and better stability. It also supports special-shaped columns and frames of terminals, warehouses and factories, ensuring safety for heavy equipment and large spaces.
Specialized Industrial Equipment
It also manufactures specialized equipment like pressure vessels, hydraulic cylinders and heavy machine tool bases. Its strength and toughness let pressure vessels withstand high internal pressure, suitable for petrochemical and energy storage fields. For cylinders and tool bases, it ensures precision and rigidity under continuous heavy loads.
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What core properties make S690Q suitable for heavy-duty engineering?
As a high-strength quenched and tempered steel, it has excellent toughness, weldability and strength-ductility balance, resisting harsh environments and heavy loads.
Why can S690Q adapt to offshore cold environments?
It has good low-temperature toughness and controlled chemical composition, ensuring anti-brittle fracture performance and weldability for offshore use.
What heat treatment state is S690Q supplied in, and how does it affect performance?
Supplied in quenched and tempered state, which refines microstructure and improves both strength and toughness for heavy load-bearing.
What components of mobile cranes use S690Q, and what advantages does it bring?
Used for booms, outriggers and main frames, enabling lighter, compact designs while maintaining load capacity and improving mobility.
How does S690Q perform in mining equipment applications?
Applied to mining components, it resists impact, pressure and abrasion, extending service life and reducing maintenance costs.
What role does S690Q play in large-span bridges?
Used in key stress-bearing parts, its high strength-to-weight ratio reduces bridge weight and enhances stability.
Can S690Q be used for telescopic arms of concrete pump trucks? Why?
Yes. Its high strength and toughness ensure safety under repeated stress and heavy loads during long-term operation.
What specialized industrial equipment can be manufactured with S690Q?
It makes pressure vessels, hydraulic cylinders and machine tool bases, ensuring high-pressure resistance and structural rigidity.
Is S690Q applicable to offshore wind power equipment? What parts does it involve?
Yes. It is used for foundation brackets and tower connections, stabilizing turbines under marine loads.
Does S690Q have good weldability for large-scale engineering assembly?
Yes. Its controlled chemical composition ensures good weldability, enabling crack-free welding with proper preheating.