Marine Angle Steel S690Q/S690QL/S690QL1 / Offshore A514/A517 Angle Steel / Unequal Angles

Leading Innovation in World-Class Structural Steel — Successfully Passed CTOD Tests!

S690QLH / S690QL1 Advanced High-Strength Steel Equal & Unequal Angles

In modern extreme engineering, green infrastructure and offshore projects, ultra-high strength steel S690QL and S690QL1 (delivering premium impact toughness even at extreme low temperature of -60°C) have been widely adopted.

Nevertheless, when welding this premium-grade steel via conventional methods, the Heat-Affected Zone (HAZ) commonly suffers from microstructure softening, embrittlement and microcrack propagation — a long-standing industry pain point.
Backed by robust R&D capability, Peakkong Special Steel applies self-developed hybrid welding technology and successfully breaks through the HAZ softening bottleneck!
More importantly, this process and welded joints have passed stringent CTOD (Crack Tip Opening Displacement) tests, verifying outstanding fracture toughness under dynamic loads and extreme stress.

This range of angle steel fully complies with international standards including EU (EN), British (BS), American (ASTM) and Japanese (JIS). Our welding procedures hold certifications from three globally authoritative bodies: SGS, TÜV and DNV, delivering unmatched safety and quality assurance for major global projects.

Supply Specifications for S690QLH / S690QL1 Angle Steel
Using our in-house high-precision hybrid welding process, Peakkong Special Steel customises angle steel with variable thickness and leg width to match project requirements. Weld seams and HAZ achieve full penetration, equal strength and high toughness:

Equal Angles
Size range: 50mm × 50mm up to 300mm × 300mm
Thickness (T): 5mm to 35mm

Unequal Angles
Size range: 75mm × 50mm up to 450mm × 250mm
Thickness (T): 6mm to 35mm

> Note: For oversized special profiles beyond the above standard range, Peakkong Special Steel provides one-to-one customisation using proprietary technology, completely removing the shape and tolerance limits imposed by traditional hot rolling mills.

Six Core Advantages of S690QL / S690QL1 Equal & Unequal Angles
1. CTOD Test Approved : Fracture mechanics assessment by authorised institutes confirms welded joints (including weld metal and the weakest HAZ region) pass CTOD evaluation. Even with minor inherent flaws, the profiles will not suffer catastrophic brittle low-stress fracture under long-term heavy loads, fatigue stress or impact.

2. Eliminate HAZ Softening & Embrittlement : Our exclusive self-developed welding technology minimises heat input and precisely controls cooling rate, ensuring mechanical properties of HAZ at angle joints match those of the base metal.

3. Resistance to Cold Brittle Fracture (Top-tier Toughness of S690QL1) : The QL1 grade maintains excellent impact energy at -60°C, perfectly suited for harsh environments such as onshore wind farms, polar regions and deep sea.

4. Ultra-High Strength & Maximum Structural Lightweighting : Minimum yield strength reaches 690 MPa, nearly twice that of conventional S355 steel. Under identical shear or axial loads, leg thickness and width can be greatly reduced, cutting component dead weight by 30%–50%.

5. High Precision & Zero Geometric Distortion : Hybrid welding generates an extremely narrow HAZ. Finished angles maintain tight tolerances for 90° perpendicularity and straightness, eliminating costly post-weld thermal straightening required in traditional fabrication; ready for installation upon delivery.

6. Break Hot-Rolling Limits for Free Customisation : Major international steel mills rarely supply hot-rolled large-size angles in S690 grade. Peakkong Special Steel breaks this constraint, customising extra heavy wall, oversized leg width or special non-standard ratio unequal angles according to engineering drawings.

Typical Applications of S690QL / S690QL1 Equal & Unequal Angles
Combining high shear resistance, anti-brittle fracture performance, ultra-low temperature tolerance, lightweight design and easy connection, S690QL/QL1 high-strength angles are widely used for:

Offshore Engineering, Offshore Wind & Polar Vessels :
Supported by DNV marine certification and CTOD fracture toughness guarantee, ideal for deck supports on offshore drilling platforms, secondary members of offshore wind jackets, berthing supports and stiffening rings for ice-class vessels.

Long-Span Spatial Trusses & Lattice Tower Structures :
Applicable for web and chord members of spatial trusses for ultra-high voltage transmission towers, broadcast towers, large stadiums and airport terminals, reducing dead weight and improving wind and seismic resistance.

High-Rise Building Wall & Core Bracing :
Used for facade support systems of skyscrapers, stiffeners inside building cores and connection angle brackets at steel joints, delivering ultra-high load capacity within compact spaces.

Heavy Construction Machinery & Vehicle Chassis :
Applied to main frames of large crawler cranes, reinforcing ribs for excavator bases and load-bearing side beams of heavy tipper trucks, significantly extending fatigue life and raising load limits of machinery.

Contact Us
If you are designing complex steel structures, large-scale infrastructure, high-rise buildings or offshore projects and wish to adopt top-tier high-strength profiles with CTOD approval and solved HAZ issues to optimise your design:

If you would like to learn more about advanced high-strength angle steel profiles, please contact us!
Peakkong Special Steel provides one-stop solutions for the most advanced, safe and globally certified special steel angle products.