High-strength low-alloy quenched and tempered structural steel plates are core foundational materials for heavy machinery, offshore engineering, bridge construction and off-highway vehicle manufacturing. Q690D (Chinese national standard high-strength steel) and S690QL (EN 10025-6 European standard high-strength structural steel) both feature a nominal yield strength of 690 MPa. Both grades enable lightweight structural design, effectively reducing equipment dead weight and logistics costs. However, significant differences in manufacturing standards, low-temperature toughness performance, impurity element control and delivery conditions result in distinct application scopes for the two steel grades.
Q690D Structural Steel Plate Product Overview
Q690D is a widely applied domestic quenched and tempered high-strength structural steel, manufactured in accordance with GB/T 1591-2018 and GB/T 16270-2009.
Grade Designation Definition
- Q: Yield strength grade
- 690: Specified minimum yield strength of 690 MPa for thin-gauge plates
- D: Charpy V-notch impact test requirement at −20 °C
Delivery Condition: TMCP (Thermo-Mechanically Controlled Rolling) or Q+T (quenched and tempered).
Derived Grades: Q690C (0 °C impact test) and Q690E (−40 °C impact test). These grades form a complete temperature-gradient product lineup for the Q690 series to adapt to diverse ambient service conditions.
S690QL Structural Steel Plate Product Overview
S690QL is a European standard high-strength structural steel complying with EN 10025-6:2019 (Material No. 1.8928).
Grade Designation Definition
- S: Structural steel
- 690: Nominal yield strength of 690 MPa
- Q: Mandatory quenched and tempered delivery condition (TMCP process is not permitted for formal commercial delivery)
- L: Charpy V-notch impact test requirement at −40 °C
This steel grade adopts stringent control on impurity elements such as sulfur and phosphorus, delivering excellent transverse low-temperature toughness. It fully complies with CE certification requirements and EN 10204 3.1/3.2 third-party inspection standards.
Derived Grades: S690Q (−20 °C impact test) and S690QL1 (−60 °C ultra-low-temperature impact test), fully covering service scenarios in various frigid regions.
With 18 years of professional industry experience, GNEE Steel specializes in the export supply of high-strength steel plates, pressure vessel steel, weathering steel and offshore structural steel. We have established mature and professional systems for production scheduling, quality inspection and full-process export services for Q690D and S690QL steel products.
If you have doubts about grade selection between S690QL and Q690D during the engineering design phase, simply provide our technical engineers with key parameters including operating temperature, project destination country and plate thickness. We will deliver a free professional material selection report within 2 working hours.
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Q690D vs S690QL Plate Differences in Toughness and Low‑Temperature Performance
Low‑temperature Charpy impact toughness serves as the key indicator for differentiating these two steel grades and defines the environmental service limits for each material.
Low‑Temperature Performance of Q690D
- Designated impact test temperature: −20 °C
- Minimum longitudinal Charpy V‑notch impact energy ≥ 34 J (typical stable mill‑delivery value ≥ 47 J)
- Maximum sulphur content: 0.025 wt‑%. Relatively higher inclusion content leads to less stable transverse toughness.
- Applicable service conditions: Ambient temperature ≥ −15 °C; construction for inland plain and temperate‑zone projects; not intended for long‑term exposure to ultra‑low‑temperature environments.
Low‑Temperature Performance of S690QL
- Designated impact test temperature: −40 °C
- Minimum longitudinal impact energy ≥ 30 J; minimum transverse impact energy ≥ 27 J (transverse toughness testing is mandatory under European standards).
- Strict sulphur control: S ≤ 0.010 wt‑%. Very low sulphide inclusions deliver excellent resistance to lamellar tearing and cold brittleness.
- Applicable service conditions: Long‑term service down to −35 °C; offshore wind power structures, polar engineering, and lifting equipment for cold‑climate regions in Northern Europe.
Q690D vs S690QL High Strength Steel Plate Application
Q690D Recommended Application Scenarios
- Domestic heavy construction machinery: hydraulic support for coal mines, telescopic boom of excavators, semi-trailer frame, concrete pump truck structural beam
- Inland municipal engineering: heavy-duty factory steel columns, inland river port fixed cranes, urban overpass main beams
- Domestic renovation and spare parts replacement projects, conventional high-strength structural parts with no strict low-temperature certification requirements
S690QL Recommended Application Scenarios
- EU exported engineering machinery: European standard mobile crane chassis, cold-region mining dump truck main beam
- Offshore engineering: self-elevating platform auxiliary structure, offshore wind turbine tower transition section, marine pipeline support
- Cold-region infrastructure: Northern Europe bridge steel structure, Russian cold-region storage tank support, Arctic engineering equipment structural parts
- Projects requiring CE certification, third-party EN standard inspection and export customs clearance
Application-Oriented Material Selection Reference
| Application Scenario | Minimum Ambient Temperature | Project Export Destination | Recommended Steel Grade | Key Reason for Selection |
|---|---|---|---|---|
| Domestic mine hydraulic support | -10℃ ~ 5℃ | Mainland China | Q690D | Cost advantage, meets domestic construction acceptance |
| Mobile crane exported to Germany | -30℃ ~ -10℃ | EU | S690QL | CE certification + -40℃ low-temperature toughness compliance |
| Inland river port crane | -15℃ ~ 10℃ | Southeast Asia | Q690D | Medium temperature meets demand, reduce material cost |
| Offshore wind power jacket accessories | -35℃ ~ 0℃ | Global marine project | S690QL | Anti-brittle fracture under marine low temperature & alternating load |
| Domestic highway heavy bridge | -18℃ ~ 15℃ | Domestic | Q690D | Stable supply, convenient cutting and welding processing |
| Arctic oil & gas auxiliary frame | -40℃ below | Northern Europe/Russia | S690QL1 upgrade (derivative grade) | Ultra-low temperature impact certification |
Q690D vs S690QL Steel Plate Price Differences and Root Cause
| Comparison Item | S690QL | Q690D | Price Difference Root Cause |
|---|---|---|---|
| Ex-factory base price | High (Premium 18%–28%) | Medium | 1. S690QL strict Q+T heat treatment only, high production energy consumption2. Strict control of S/P impurity elements, high raw material refining cost3. European standard inspection requires transverse impact, double flaw detection cost |
| Certification Cost | High (3.1/3.2 certificate mandatory) | Low (Domestic MTC certificate) | EU third-party inspection certification fees are included in the unit price of S690QL |
| Inventory Cost | Higher customized inventory | Large conventional spot inventory | S690QL multi-spec heat treatment customization, low stock turnover |
| Processing loss rate | Low | Slightly higher | High purity of S690QL reduces cutting cracking loss during thick plate processing |
| Applicable Project Cost | High total project investment | Low comprehensive material cost | Q690D is the preferred cost reduction choice for non-export temperate projects |
Q690D vs S690QL High Strength Structural Steel Plate Chemical Composition
| Element | Q690D (GB/T 16270) | S690QL (EN 10025-6 1.8928) |
|---|---|---|
| C | ≤0.20 | ≤0.20 |
| Si | ≤0.50 | ≤0.80 |
| Mn | ≤1.80 | ≤1.70 |
| P | ≤0.030 | ≤0.025 |
| S | ≤0.025 | ≤0.010 |
| Cr | ≤1.00 | ≤1.50 |
| Ni | ≤0.80 | ≤2.00 |
| Mo | ≤0.30 | ≤0.70 |
| B | ≤0.004 | ≤0.005 |
Q690D vs S690QL High Strength Structural Steel Plate Mechanical Property
| Performance Index | Plate Thickness | Q690D | S690QL |
|---|---|---|---|
| Yield Strength ReH (MPa) | ≤16mm / ≤50mm | ≥690 | ≥690 |
| 16–40mm / 50–100mm | ≥670 | ≥650 | |
| 40–100mm / 100–150mm | ≥650 | ≥630 | |
| Tensile Strength Rm (MPa) | All thickness | 770–940 | 770–940 |
| Elongation A (%) | All thickness | ≥14 | ≥14 |
| Charpy Impact Temperature | -20℃ | -40℃ | |
| Charpy Impact Energy KV2 (J) | Longitudinal | ≥34 | ≥30 |
| Transverse | Not mandatory inspection | ≥27 | |
| Delivery Condition | TMCP or Q+T | Only Q+T Quenched & Tempered |
Q690D S690QL High-Strength Alloy Steel Plate Specification
|
Product Name |
Q690D S690QL High-Strength Alloy Steel Plate |
|
Width |
0.6m-3m or as required |
|
Length |
4m-12m or as required |
|
Thickness |
3mm-300mm or as required |
|
Standard |
GB/T 16270-2009; EN 10025-6:2019 |
|
Surface Treatment |
According to customer requirement |
|
Material |
Q690D; S690QL |
|
Shipment time |
Within 15-20 workdays after receiving deposit or L/C |
|
Export packing |
Waterproof paper, and steel strip pack |
GNEE Steel Supporting Services
Third‑Party Certification Support
Issue mill test certificates complying with EN 10204 3.1; cooperate with institutes including SGS, BV and TÜV to complete EN 10204 3.2 third‑party inspection and certification for export projects.
Fabrication Services
Flame / plasma cutting, CNC precision cutting, edge beveling, shot blasting for rust removal, anti‑corrosive primer coating, custom Z‑grade steel (Z15 / Z25 / Z35), and graded ultrasonic testing.
Export Logistics Solutions
Container loading, seaworthy export packaging, customs documentation handling, break‑bulk door‑to‑door delivery, and specialized export document processing for European and offshore engineering projects.
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FAQ
What is the approximate equivalent grade of S690QL in Chinese standard?
The approximate Chinese standard equivalent grade for European S690QL (governed by EN 10025-6) is Q690E under the Chinese national standard GB/T 16270. Both designate high-strength, quenched and tempered structural steel with a minimum yield strength of 690 MPa and matched low-temperature impact properties.
Why is S690QL forbidden to use TMCP rolling delivery?
Under the [EN 10025-6](gangsteel.net - Gangsteel) standard, S690QL is strictly designated as a Quenched and Tempered (Q+T) steel. It is not "forbidden" due to a legal ban, but rather because Thermo-Mechanical Control Process (TMCP) rolling alone cannot achieve the mandatory 690 MPa yield strength and guaranteed -40°C low-temperature impact toughness required by its metallurgical specification.
What is the price of Q690D plate?
The price of a Q690D high-strength low-alloy steel plate generally ranges from $450 to $720 per metric ton, depending on the order volume, thickness, and market conditions. Smaller retail or single-ton orders sit on the higher end ($550–$720/ton), while bulk mill orders of 100+ tons drop closer to $450–$500/ton.
What is the hardness of Q690D plate?
The Brinell hardness of Q690D high-strength structural steel plate typically ranges from 235 to 293 HBW (for nominal thicknesses up to 20 mm).
