S690QL1 High Strength Structural Steel Plate

1. What is S690QL1 High Strength Structural Steel Plate?

EN 10025-6 S690QL1 is a quenched and tempered high-strength structural steel plate for ultra-low-temperature applications (Material Number: 1.8988). It features high structural strength (yield strength ≥ 690 MPa), excellent low-temperature impact toughness (impact energy absorption ≥ 30 J at -60°C), and good weldability and machinability. It is specifically designed for lightweight, heavy-load structural components operating in Arctic, high-altitude, and offshore cold-climate environments.

S690QL1 high-strength structural steel plates offer excellent load-bearing capacity and resistance to low-temperature brittle fracture. They can significantly reduce structural weight, increase payload capacity, and lower manufacturing and operating costs, while maintaining structural safety and reliability under the most demanding operating conditions. They are widely used in load-bearing components for construction machinery, mining equipment, and large steel structures that require high strength, good low-temperature toughness, and weldability.

Our company supplies S690QL1 high-strength steel plates in a variety of specifications. Each batch undergoes rigorous factory inspection, ensuring stable quality and consistent performance. We provide an EN 10204 3.1 Manufacturer’s Test Certificate (MTC) with every shipment, support third-party inspections, and ensure full material traceability. We also offer processing services such as custom sizing, precision cutting, and surface treatment.

2. Meaning of the Grade Designation “EN10025-6 S690QL1”

Note:

1) Carbon (C): Maintained at a low level to balance strength and weldability while avoiding welding cracks.

2) Alloying elements (Cr, Mo, Ni, V): Enhance strength through solid solution strengthening and precipitation strengthening, while also improving low-temperature toughness.

3) Harmful elements (P, S): Strictly restricted to reduce steel brittleness and susceptibility to hot cracking.

Note:

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

1. High yield strength and strong load-bearing capacity

The high strength helps optimize load-bearing structures and meets the strength requirements for heavy-duty equipment and large engineering components.

2. Excellent low-temperature impact toughness

Meets the requirements of the Charpy V-notch impact test at -60°C, with a minimum impact energy absorption of 30 J for longitudinal specimens, helping to reduce the risk of brittle fracture under low-temperature operating conditions.

3. Facilitates structural weight reduction

While meeting strength, stiffness, stability, and fatigue design requirements, the plate thickness and steel consumption of certain structural components can be optimized to reduce the equipment’s dead weight and improve the payload utilization of products such as lifting equipment and transportation vehicles.

4. Quenching and Tempering: Balancing Strength and Toughness

The quenching and tempering process imparts high strength and specified impact toughness to the steel plates, making them suitable for engineering structures subjected to heavy loads and harsh operating environments.

5. Suitable for Engineering Fabrication and Welding

The steel can be cut, grooved, formed, and welded according to certified processes. The fabrication of high-strength steel requires strict control of preheating, welding heat input, hydrogen content, and welding consumable compatibility to ensure the strength and low-temperature toughness of welded joints.

6. Suitable for Demanding Engineering Projects in Cold Regions

It can be used in cold regions for lifting equipment, mining machinery, heavy-duty vehicles, and other high-load-bearing structures, and is particularly suitable for applications where design codes explicitly require lower-temperature impact toughness.

1. Cranes and Lifting Equipment

1) Boom sections for truck cranes and all-terrain cranes;

2) Structural components for large crawler cranes;

3) Aerial work platforms and high-load-bearing support components.

High-strength steel plates are used to enhance load-bearing capacity while reducing the structural weight, provided that design requirements are met.

2. Mining and Heavy Construction Machinery

1) Large excavators and mining loaders;

2) Chassis and load-bearing structures for mining dump trucks;

3) Drilling rigs, open-pit mining equipment, and hydraulic support structures.

Suitable for critical structural components subjected to significant static and dynamic loads under complex operating conditions.

3. Offshore Engineering and Steel Structures in Cold Regions

1) Load-bearing structures for offshore engineering platforms;

2) Frames for engineering equipment in cold regions;

3) Welded load-bearing structures used in low-temperature environments.

Low-temperature toughness is a key consideration for selecting S690QL1, but corrosion resistance in marine environments must still be ensured through coatings or other protective measures.

4. Heavy-Duty Trucks and Transportation Equipment

1) Chassis and frames of heavy-duty vehicles;

2) Load-bearing structures of semi-trailers;

3) Container transport and material handling equipment.

Following structural design and fatigue verification, high-strength steel can be used to achieve weight reduction and increase payload capacity.

5. Bridges and Large Building Structures

1) Load-bearing members in large-span steel structures;

2) Heavy-duty industrial plant structures;

3) Engineering structures with high requirements for weight and load-bearing performance.

The decision to use this material should be made in accordance with structural codes, connection design, fatigue performance, and project certification requirements.

The Difference Between Temperature Grades and Quality Grades in the S690 Series Steel

S690Q: Impact energy ≥30J at -20°C (longitudinal), ≥27J (transverse)

S690QL: Impact energy ≥30J at -40°C (longitudinal), ≥27J (transverse)

S690QL1: Impact energy ≥30J at -60°C (longitudinal), ≥27J (transverse)