S690QL1 steel is a high-strength, quenched and tempered structural steel plate, defined by the EN 10025-6 standard. It is primarily used for demanding applications that require exceptional strength and toughness, particularly in cold environments.
Key Properties
The 'S' in S690QL1 stands for structural steel, '690' indicates the minimum yield strength in MPa, 'Q' means it is supplied in the quenched and tempered condition, and 'L1' specifies that it has enhanced impact toughness tested at -60°C.
| Property | Value (for nominal thickness ≤ 50mm) | Source |
|---|---|---|
| Minimum Yield Strength | 690 MPa | |
| Tensile Strength | 770 - 940 MPa | |
| Elongation | Minimum 14% | |
| Impact Toughness | Minimum 30 J at -60°C (Transverse) |
Common Applications
S690QL1 steel is known for its high strength-to-weight ratio, which allows for lighter designs without compromising safety or performance. Its superior mechanical properties make it suitable for:
Heavy engineering and construction machinery
Cranes and lifting equipment
Bridges and offshore platforms
Mining equipment
Pressure vessels and structural components
Chemical composition % of steel S690QL1 (1.8988): EN 10025-6-2004
| 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 0.02 | max 0.01 | 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 S690QL1 (1.8988)
| 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° 60 |
-20° 50 |
-40° 40 |
-60° 30 |
| A - Min. elongation Lo = 5,65 √ So (%) | 14 |
S690QL1 is primarily governed by the European standard EN 10025-6, which specifically covers quenched and tempered high-strength structural steels. This standard defines the chemical composition, mechanical properties, testing methods, and toughness classifications for grades like S690QL1.
1. Primary Material Standard
EN 10025-6: Hot rolled products of structural steels – Part 6: Technical delivery conditions for flat products of high yield strength structural steels in the quenched and tempered condition.
This is the core standard that defines the "QL1" designation.
It specifies the mandatory -60°C Charpy V-notch impact test with a minimum average energy of 40 Joules.
It covers all requirements for manufacturing, delivery, and testing.
2. Complementary Testing & Certification Standards
EN 10204: Defines the types of inspection documents (e.g., Type 3.1 Inspection Certificate, which is mandatory for S690QL1, requiring validation by an independent inspector approved by the manufacturer).
EN ISO 148-1: Standard for Charpy impact testing.
EN ISO 6892-1: Standard for tensile testing.
EN ISO 6506-1: Standard for Brinell hardness testing.
3. Design & Fabrication Standards (Application-Specific)
These are not material standards but are critical for how S690QL1 is used:
EN 1993-1-10 (Eurocode 3): Provides guidelines for selecting steel grades based on toughness requirements for structural design, considering temperature, stress, and thickness.
ISO 9606-1 / EN 287-1: Standards for qualifying welders for steel.
EN ISO 15614-1: Standard for qualifying welding procedures for steel.
4. Equivalent Specifications in Other Regional Standards
While EN 10025-6 is the defining standard, equivalent grades may be specified in other systems (though exact correspondence is not always 1:1):
ISO 4950-3: May have similar high-strength quenched and tempered grades.
ASTM A514 / A517: These are U.S. specifications for quenched and tempered alloy steel plates, but no direct equivalent exists that matches the exact "QL1" low-temperature toughness classification. Grade 690 would be the closest in strength.
Summary:
For S690QL1, the non-negotiable standard is EN 10025-6. Any order or specification must reference this standard to guarantee the -60°C impact toughness. Certification (EN 10204 Type 3.1) and application-specific design codes (like Eurocode) are integral to its proper use in regulated engineering projects.
What is S690QL1 steel?
S690QL1 is a high-strength quenched and tempered structural steel grade with a minimum yield strength of 690 MPa, optimized for enhanced toughness at low temperatures (down to -60°C).
What does "QL1" mean in S690QL1?
The "QL1" indicates a sub-grade with specific impact toughness requirements at -60°C, ensuring higher resistance to brittle fracture in extreme cold environments.
What are the main applications of S690QL1?
It is used in critical components for Arctic engineering, offshore platforms, wind turbine towers in cold climates, and heavy-duty mining equipment operating below -40°C.
How does S690QL1 differ from S690QL?
S690QL1 guarantees impact toughness at a lower temperature (-60°C) compared to S690QL (typically -40°C), making it suitable for more severe cold conditions.
What is the chemical composition of S690QL1?
It contains low-carbon alloying elements like manganese, silicon, nickel, chromium, molybdenum, and vanadium, with strict control of impurities to ensure weldability and toughness.
How to weld S690QL1 steel correctly?
Welding requires low-hydrogen electrodes, preheating (100-150°C), controlled heat input, and post-weld stress relief to maintain toughness and prevent hydrogen-induced cracking.
Is S690QL1 corrosion resistant?
No, S690QL1 is not inherently corrosion-resistant. It requires protective coatings (e.g., galvanizing or painting) for use in corrosive environments.
What standards apply to S690QL1?
It is defined under European standard EN 10025-6, with additional specifications for low-temperature impact testing and quality levels.
Can S690QL1 be machined easily?
Machining S690QL1 is challenging due to its high strength; it requires rigid tools, adequate cooling, and optimized cutting parameters to avoid excessive tool wear.
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.
