S690QL High Strength Structural Steel Plate

1. What is S690QL High Strength Structural Steel Plate?

S690QL is a quenched and tempered high-yield-strength structural steel plate that complies with the European standard EN 10025-6. material designation 1.8928, produced using a quenching and tempering (Q+T) process. It features high strength (yield strength ≥ 690 MPa), good low-temperature impact toughness (impact energy absorption ≥ 30 J at -40°C), and significant potential for structural weight reduction.

S690QL high-strength structural steel plates are primarily used in cranes, construction machinery, mining equipment, heavy-duty transport vehicles, and high-load steel structures, and are particularly suitable for engineering projects with high requirements for load-bearing capacity, equipment weight, and low-temperature toughness.

The S690QL high-strength steel plates we supply come with an EN 10204 3.1 factory test certificate; an EN 10204 3.2 certificate issued following third-party witnessed testing can be provided upon request. We offer a comprehensive range of product specifications with selectable thicknesses, widths, and lengths, as well as processing services such as precision cutting and surface treatment.

2. Meaning of the Grade Designation “EN10025-6 S690QL”

Note:

1) P and S are detrimental elements, strictly limited to avoid brittleness;

2) Alloying elements like Cr, Mo, Ni enhance strength and toughness;

3) Microalloying elements V, Nb, Ti refine the grain structure to optimize mechanical properties.

Note:

Yield strength and tensile strength decrease slightly as thickness increases; refer to the MTC for specific values.

1. High yield strength and outstanding load-bearing capacity

Its high-strength properties enable it to withstand heavy loads, meeting the design requirements of heavy-duty equipment and high-load engineering structures.

2. Excellent potential for structural weight reduction

Under equivalent loads, sheet thickness can be reduced, lowering the dead weight and increasing the equipment’s payload capacity, while also reducing steel consumption, welding volume, and transportation and installation costs. It is suitable for lightweight designs of load-bearing components.

3. Good low-temperature impact toughness

Charpy V-notch impact energy at -40°C ≥ 30 J; resistant to brittle fracture under low-temperature conditions, making it suitable for dynamic load-bearing structures such as construction machinery in cold regions, wind power equipment, and bridges in extremely cold climates.

4. Excellent Fatigue Resistance and Stability Under Dynamic Loads

The quenching and tempering process yields a uniform, fine-grained tempered microstructure with high crack resistance, resulting in a longer fatigue life under long-term alternating loads.

It is suitable for applications involving continuous vibration and repeated impact, ensuring high structural safety.

5. Suitable for Engineering Machining and Welding

It can be cut, grooved, formed, and welded according to design requirements.

For high-strength steel, welding heat input, preheating conditions, welding consumable selection, and hydrogen content must be properly controlled to prevent cold cracks and ensure the performance of welded joints.

6. Wide Range of Applications and Significant Overall Economic Benefits

Suitable for large cranes, mining machinery, construction vehicles, heavy-duty transport equipment, and other high-load structures.

Proper design can reduce material consumption, improve equipment load efficiency, and help lower life-cycle costs.

1. Construction Machinery and Lifting Equipment

Used in truck crane booms, telescoping booms, tower crane structural components, excavator booms, and load-bearing frames for heavy-duty equipment.

2. Mining Machinery and Earthmoving Equipment

Used in the frames of mining transport vehicles, structural components of excavation equipment, load-bearing parts of loaders, frames for mining conveyor equipment, and structural components of large construction machinery.

3. Heavy-Duty Transport Vehicles and Trailers

Used in heavy-duty truck frames, low-bed semi-trailers, special-purpose transport vehicle chassis, and load-bearing structures.

4. Bridges and Large Steel Structures

Used in high-stress connection components, load-bearing structures, industrial plant components, and large steel structures.

5. Offshore Engineering and Port Equipment

Used in port lifting equipment, offshore platform load-bearing structures, floating lifting equipment, and offshore engineering machinery.

6. Energy and Heavy Industrial Equipment

Used in load-bearing components for wind power equipment, hydraulic gates, structural components for pressure vessels, and large-scale industrial equipment.

Processing Precautions

1. Welding

It falls under the "weldable steel grade," but note the following: Preheating is required before welding (preheating temperature adjusted based on thickness, typically ≥100°C), and stress relief heat treatment is recommended after welding to avoid welding cracks. The use of low-hydrogen welding materials (such as E11018-G) is advised.

2. Cutting

The high strength results in significant cutting resistance. It is necessary to use carbide tools and reduce cutting speeds.

3. Cold Working

Cold forming processes such as bending and stamping can be performed at room temperature, but the forming force must be increased accordingly. High-temperature forming should be avoided (temperatures exceeding 250°C may affect the tempered microstructure).

Precautions for Procurement and Use

1. Requirements for the Mill Test Certificate

When purchasing, it is essential to explicitly require the steel mill to provide a Mill Test Certificate compliant with EN 10025-6, which includes mechanical properties, chemical composition, nondestructive testing grades (such as EN 10160 Class B inspection), and other relevant details.

2. Thickness Impact

Properties may degrade when the thickness exceeds 50mm. It is necessary to confirm specific performance indicators for large thicknesses (e.g., >100mm) with the steel mill in advance.

3. Welding Process

A suitable Welding Procedure Specification (WPS) must be developed, with strict control over preheating and post-weld heat treatment parameters.

• S690QL Material Properties