S690QL Steel Plate
The standard for heavy-load structures, with a minimum 690 MPa yield strength and −40°C impact toughness. Available ex-stock in the 8 mm – 120 mm thickness range, in the Strenx 700E and DILLIMAX 690T brands.
What Is S690QL?
S690QL is a high-strength structural steel grade defined under the European standard EN 10025-6, produced by quenching and tempering. It is developed for heavy-load engineering applications that require high strength.
What Does the S690QL Designation Mean?
Indicates that the material is suitable for structural use.
At least 690 MPa yield strength; nearly double that of standard steels such as S355.
Quenching and tempering heat treatment; delivers a combination of high strength and toughness.
Guarantees a minimum impact energy of 27 Joules at −40°C.
The high yield strength of S690QL allows thinner sections to be used in structural designs. This reduces total structure weight, increases load capacity and lowers material cost. The plate thickness required in a structure designed with S355 can be reduced by roughly 30–40% by switching to S690QL.
S690QL Chemical Composition
Maximum chemical composition values for S690QL steel according to EN 10025-6 (ladle analysis, % by weight):
| Element | Symbol | Maximum Value (%) |
|---|---|---|
| Carbon | C | 0,20 |
| Silicon | Si | 0,80 |
| Manganese | Mn | 1,70 |
| Phosphorus | P | 0,020 |
| Sulfur | S | 0,010 |
| Chromium | Cr | 1,50 |
| Molybdenum | Mo | 0,70 |
| Nickel | Ni | 2,00 |
| Vanadium | V | 0,12 |
| Titanium | Ti | 0,05 |
| Boron | B | 0,005 |
| Niobium | Nb | 0,06 |
Note: The values are the maximums permitted by EN 10025-6; the actual composition may vary according to the manufacturer and melt analysis. The carbon equivalent (CEV) is typically in the 0,65–0,82 range.
S690QL Mechanical Properties
Guaranteed mechanical values for S690QL steel according to EN 10025-6:
| Property | Value | Unit | Description |
|---|---|---|---|
| Yield Strength (ReH) | ≥ 690 | MPa | Minimum for thickness ≤ 50 mm |
| Tensile Strength (Rm) | 770 – 940 | MPa | Range for thickness ≤ 50 mm |
| Elongation at Fracture (A) | ≥ 14 | % | Transverse specimen, L₀ = 5,65√S₀ |
| Impact Energy (−40°C) | ≥ 30 | J | Charpy V, longitudinal specimen, avg. of 3 tests |
| Hardness (typical) | 235 – 280 | HBW | Brinell, reference value |
Note: Mechanical values vary with thickness. For thicknesses above 50 mm the minimum yield decreases progressively (50–100 mm ≥ 650 MPa, 100–150 mm ≥ 630 MPa).
S690QL Applications
S690QL is the preferred choice across many industrial fields that require weight optimization and high strength:
Structural Construction
Lightweight members in high-rise buildings, industrial plants, bridges and wide-span roof systems.
Cranes & Lifting
High load capacity in mobile crane booms, tower crane jibs, platform cranes and port equipment.
Mining
Impact resistance in excavator buckets, dump bodies, crusher frames and conveyor systems.
Marine & Offshore
Low-temperature strength in ship hull structures, offshore platforms and floating cranes.
Energy
Wind turbine towers, hydroelectric gates, pressure vessels and pipelines.
Heavy Machinery
Hydraulic presses, steel-construction frames and heavy-equipment bodies.
S690QL Material Equivalents
Approximate equivalents of S690QL steel in different standards and brands:
| Standard / Brand | Grade | Country / Manufacturer | Description |
|---|---|---|---|
| EN 10025-6 | S690QL | Europe | Reference standard |
| ASTM | A514 Grade Q / A517 | USA | 100 ksi class, similar mechanical properties |
| SSAB | Strenx 700 E | Sweden | Optimized weldability |
| Dillinger | DILLIMAX 690T | Germany | High-toughness version |
| ThyssenKrupp | NAXTRA 70 | Germany | High-strength commercial grade |
| JFE Steel | Welten 780E | Japan | Equivalent high-strength steel |
Note: Equivalents are not identical; minor differences may exist in chemical composition and mechanical values. A suitability check on a per-project basis is recommended.
S690QL Weldability
S690QL is a weldable steel, but because of its high-strength class it requires low-hydrogen methods and controlled heat input. Recommended preheat temperatures by thickness:
| Plate Thickness | Preheat | Max. Interpass |
|---|---|---|
| ≤ 20 mm | 100 °C | 250 °C |
| 20 – 40 mm | 125 – 150 °C | 250 °C |
| 40 – 80 mm | 150 – 175 °C | 250 °C |
| > 80 mm | 175 – 200 °C | 250 °C |
- Welding method: Low-hydrogen MIG/MAG, TIG or submerged arc welding.
- Filler metal: Equal-strength or slightly undermatching consumable.
- Heat input: Typically 0,5 – 2,5 kJ/mm, controlled per the manufacturer's recommendation.
- PWHT: Generally not required; stress-relief annealing may be applied for thick sections.
S690QL Bending Capability
Cold bending is possible; to prevent cracking, the minimum inner bending radius (R) is determined by the plate thickness (t). A lower radius is possible when the bending axis is perpendicular to the rolling direction.
| Bending Direction | Min. Inner Radius | Min. V-Die Opening |
|---|---|---|
| Perpendicular to rolling direction (recommended) | 3,0 × t | ≈ 10 × t |
| Parallel to rolling direction | 4,0 × t | ≈ 12 × t |
Note: Values are for reference; actual values vary by brand (Strenx 700E may allow lower radii) and plate surface condition. Sacdan Adam offers press-brake bending services.
S690QL Stock & Services
At Sacdan Adam we keep S690QL high-strength steel plate continuously in stock. We offer fast delivery in the following thicknesses and brands:
Thickness Range
8 – 120 mm standard thicknesses:
8 · 10 · 12 · 15 · 20 · 25 · 30 · 35 · 40 · 50 · 60 · 70 · 80 · 100 · 120 mm
Available Brands
- Strenx 700 E — SSAB / Sweden
- DILLIMAX 690T — Dillinger / Germany
Certificates
- EN 10204 — 3.1 Inspection Certificate
- Mill test certificate
- 3.2 certificate on request
Additional Services
- Laser / plasma / oxy-fuel cutting
- Press-brake bending
- Nationwide delivery across Turkey
Frequently Asked Questions About S690QL
Is S690QL weldable?
Yes. S690QL is a weldable steel, but because of its high-strength class some rules must be observed:
- Preheat: 100–200°C depending on thickness.
- Method: Low-hydrogen MIG/MAG, TIG, submerged arc.
- Filler: Equal-strength or slightly undermatching consumable.
- Interpass: Maximum ~250°C.
Post-weld heat treatment (PWHT) is generally not required; stress-relief annealing may be applied for thick sections.
What is the difference between S690QL and S690QL1?
The main difference is the temperature at which the Charpy impact test is performed:
- S690QL: min. 27 J at −40°C
- S690QL1: min. 27 J at −60°C
Because S690QL1 retains its toughness at lower temperatures, it has tighter controls on chemical composition and is preferred for Arctic / extreme cold conditions. The mechanical strength values are the same for both grades.
To which standard is S690QL produced?
S690QL is produced to the European 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"
The standard covers chemical composition, mechanical guarantees, heat treatment conditions, inspection/test requirements and tolerances. In the USA, ASTM A514 is a close equivalent.
What is the hardness of S690QL?
The typical hardness of S690QL is approximately 235–280 HBW (Brinell). This value depends on the martensitic/bainitic microstructure produced by quenching and tempering.
For comparison: S690QL is not as hard as wear-resistant steels (Hardox 400 ≈ 400 HBW), but it is noticeably harder than standard structural steel (S355 ≈ 160 HBW). S690QL is optimized for structural strength rather than wear resistance.
S690QL Steel Plate, Delivered Ex-Stock
Source S690QL plate from 8 mm to 120 mm in the Strenx 700E and DILLIMAX 690T brands, ex-stock. Contact us for delivery including cutting and bending.