Quenched-and-tempered high-strength steel plates of 690 MPa grade serve as the core structural material for structural lightweighting, heavy-load bearing, cost reduction and efficiency improvement in construction machinery, lifting equipment, mining vehicles, wind power facilities and cold-region infrastructure construction. The mainstream commercial grades fall into four flagship products: S690Q and S690QL under the European standard EN 10025-6 system, as well as Q690D and Q690E complying with Chinese national standard GB/T 16270.
With more than 18 years of deep cultivation in the import and export business of high-strength steel plates, GNEE Steel boasts ten-thousand-ton spot inventory, a full-process quality inspection system and abundant practical experience in overseas heavy industry project execution. Supported by original mill test certificates (MTC), third-party physical inspection reports issued by SGS and batch qualification rates of ultrasonic testing, we provide standardized technical support for engineering design, foreign trade quotation and bulk raw material procurement.
Do you need original manufacturer material certificates for four specific grades, re-inspection reports for low-temperature impact toughness, price quotes for in-stock specifications, or welding procedure specifications? You can consult directly with GNEE's technical engineers to receive complimentary material equivalence reports and project-specific material selection plans.
What is S690Q Plate?
Applicable Standard: EN 10025-6
Grade Definition: S = Structural Steel; 690 = Minimum yield strength of 690 MPa; Q = Quenched and tempered delivery condition.
S690Q plates only require satisfactory Charpy impact toughness at -20°C with no mandatory low-temperature performance requirements. Impurity elements are controlled via LF ladle refining for molten steel. The plates feature excellent fl
What is S690QL Plate?
Applicable Standard: EN 10025-6
The suffix L stands for Low temperature with quenched-and-tempered delivery condition. Passing Charpy V-notch impact test at -40°C is a mandatory acceptance criterion.
Manufactured via VD vacuum degassing clean steel smelting, the steel has extremely low internal porosity and sulfide inclusions. Thick plates deliver uniform and stable through-thickness performance. Customization for Z-direction lamellar tearing resistance is available, and the steel is qualified for CE structural marking for EU projects.
What is Q690D Plate?
Applicable Standard: GB/T 16270-2013
Q denotes yield strength designation; Grade D requires impact testing at -20°C.
It is a mature mass-produced mid-tier high-strength steel in China. Grain strengthening is realized through vanadium and niobium microalloying without costly high-nickel alloy additions. It enjoys abundant spot availability and prominent procurement cost advantages.
What is Q690E Plate?
Applicable Standard: GB/T 16270-2013
Grade E is specified for Charpy impact testing at -40°C, representing the top-tier low-temperature high-strength steel within the domestic 690 MPa grade series.
Stringent control is implemented on detrimental phosphorus (P) and sulfur (S) impurities to guarantee consistent low-temperature impact performance across production batches. As a domestic equivalent alternative to imported S690QL, it drastically shortens the lead time of imported steel and cuts overall procurement expenditure.
Main Difference: S690Q vs Q690D vs S690QL vs Q690E Plate
Low-Temperature Toughness Grade
S690Q only guarantees Charpy toughness at -20°C. Q690D satisfies service requirements at moderate-low temperature of -20°C. Both S690QL and Q690E achieve ultra-low-temperature toughness at -40°C, serving as the critical threshold for material selection under cold-climate working conditions.
Applicable Standard System
S690Q and S690QL comply with European standards, eligible for direct application in export projects requiring EU CE marking and DNV marine survey certification. Q690D and Q690E follow Chinese national standards, which can be directly adopted for domestic projects. They cannot be used as direct equivalent substitutes for load-bearing components exported to the European Union unless validated by third-party material certification.
Metallurgical Cleanliness
S690QL is produced with vacuum degassing refining, with total gaseous impurities controlled at ≤25 ppm, resulting in minimal property deviation at the core of thick plates. The refining grade of the other three steel grades decreases sequentially, leading to higher fluctuation of low-temperature mechanical properties for thick gauge plates.
Alloy Design & Cost Profile
The European S690 series features a well-balanced alloy composition with outstanding adaptability for export projects. The Q690 series adopts a low-cost microalloying design, delivering remarkable price advantages with readily available domestic spot stocks.
Quick Overview Comparison Table: S690Q vs Q690D vs S690QL vs Q690E
| Comparison Item | S690Q | S690QL | Q690D | Q690E |
|---|---|---|---|---|
| Applicable Standard | EN 10025-6 | EN 10025-6 | GB/T 16270-2013 | GB/T 16270-2013 |
| Heat Treatment Condition | Quenched & Tempered (Q+T) | Quenched & Tempered (Q+T) | Quenched & Tempered (Q+T) | Quenched & Tempered (Q+T) |
| Charpy Impact Test Temperature | -20°C | -40°C | -20°C | -40°C |
| Primary Application Region | Southern Europe, Middle East Normal-Temperature Projects | Northern Europe, Russia, Offshore Cold-Region Projects | Domestic Temperate Heavy Industry | Domestic Cold-Region Projects, Import Substitution |
| Maximum Deliverable Thickness | 150 mm | 150 mm | 150 mm | 150 mm |
| Factory UT Pass Rate | 99.2% | 99.5% | 99.1% | 99.3% |
| Cost Tier | Medium | High | Lowest | Medium-Low |
S690Q Q690D S690QL Q690E High Strength Steel Plate Specification
| Item | Specification |
|---|---|
| Product Name | 690MPa High Strength Steel Plate |
| Available Grades | S690Q, S690QL, Q690D, Q690E |
| Standards | EN 10025-6, GB/T 16270 |
| Steel Category | Quenched and Tempered High Strength Structural Steel |
| Thickness | 6–150 mm |
| Width | 1500–4000 mm |
| Length | 3000–18000 mm |
| Delivery State | Quenched and Tempered (Q+T) |
| Heat Treatment | Quenching + Tempering |
| Testing | Chemical Analysis, Tensile Test, Impact Test, Hardness Test, Ultrasonic Testing (Optional) |
| Inspection Certificate | EN 10204 3.1 / 3.2, Mill Test Certificate |
| Surface Treatment | Shot Blasting, Primer Coating (Optional) |
| Cutting Service | CNC Cutting, Flame Cutting, Plasma Cutting |
S690Q vs Q690D vs S690QL vs Q690E: Chemical Composition
| Element | S690Q | S690QL | Q690D | Q690E |
|---|---|---|---|---|
| C | 0.20 | 0.20 | 0.20 | 0.20 |
| Si | 0.60 | 0.60 | 0.55 | 0.55 |
| Mn | 1.70 | 1.70 | 1.70 | 1.70 |
| P | 0.020 | 0.018 | 0.025 | 0.020 |
| S | 0.015 | 0.012 | 0.020 | 0.015 |
| Cr | ≤0.80 | ≤0.80 | ≤0.60 | ≤0.60 |
| Ni | ≤0.60 | ≤0.60 | ≤0.40 | ≤0.40 |
| Mo | ≤0.50 | ≤0.50 | ≤0.40 | ≤0.40 |
| B | ≤0.0005 | ≤0.0005 | ≤0.0005 | ≤0.0005 |
S690Q vs Q690D vs S690QL vs Q690E: Mechanical Property
| Performance Index | S690Q | S690QL | Q690D | Q690E |
|---|---|---|---|---|
| Minimum Yield Strength Rp0.2 (MPa) | ≥690 | ≥690 | ≥690 | ≥690 |
| Specified Tensile Strength Rm Range (MPa) | 770~940 | 770~940 | 770~930 | 770~930 |
| Minimum Elongation A (%) | ≥14 | ≥14 | ≥14 | ≥14 |
| Measured Brinell Hardness HB Range | 265~325 | 265~325 | 260~320 | 260~320 |
| Minimum Longitudinal Charpy Impact Energy (J) | 30 (-20°C) | 30 (-40°C) | 47 (-20°C) | 47 (-40°C) |
Impact Toughness and Low-Temperature Service Performance: S690Q vs Q690D vs S690QL vs Q690E
Low-temperature impact toughness directly governs the steel's resistance to brittle fracture and fatigue at subzero temperatures, acting as the core criterion for material selection in alpine and frigid projects:
S690Q
Certified and validated with mandatory Charpy V-notch impact test at -20°C, delivering stable high-cycle fatigue performance under conventional cold ambient conditions. Its fatigue strength declines significantly at temperatures below -30°C, accompanied by a remarkable increase in cold cracking susceptibility within the weld heat-affected zone (HAZ). This grade is applicable for structures serving in temperate and mild cold regions with a minimum service temperature above -20°C, while it is not suitable for long-term exposure to extreme sub-zero environments below -30°C.
S690QL
Mandatory full-thickness Charpy impact testing at -40°C is enforced. Benefiting from high molten steel cleanliness, the through-thickness impact energy difference at the core of 100–150 mm heavy plates is merely 8.3 J, the fatigue limit at -40°C reaches ≥470 MPa, and the lamellar tearing defect rate is below 0.5%. Validated by ten years of fatigue performance in Northern European wind power and Arctic mining applications, it ranks first among the four grades in terms of low-temperature stability for thick plates.
Q690D
Passes Charpy impact test at -20°C with a fatigue limit of ≥460 MPa at -20°C, making it ideal for winter operating conditions along the Yellow River Basin. Fatigue life declines by 28% once the operating temperature falls below the critical threshold of -20°C. It is the cost-performance leader for domestic heavy-load machinery used at ambient temperatures.
Q690E
Its low-temperature toughness at -40°C matches that of S690QL, with a batch impact test pass rate of 99.3%. Domestic clean steel smelting technology reduces inclusion defects, resulting in a third-party material re-inspection pass rate exceeding 99% for frigid service conditions. Its procurement cost is 15%–22% lower compared with S690QL.
S690Q vs Q690D vs S690QL vs Q690E High Strength Plate: Typical Application Scenarios
S690Q Applications
Main beams for semi-trailers in Spain and Italy, lifting machinery for Mediterranean ports, heavy load-bearing steel girders for European factory buildings, and ambient-temperature dump trucks for Middle Eastern mines.
S690QL Applications
Flanges for wind turbine towers in Finland, cranes for cold-region operations in Russia, auxiliary structures for offshore platforms in the North Sea, and engineering vehicles for Arctic mining areas.
Q690D Applications
Main booms of crawler cranes, dump trucks for open-pit coal mines in North China, bridge reinforcement projects along the Yellow River Basin, and high-strength cargo bodies for muck trucks.
Q690E Applications
Heavy-duty chassis for open-pit mines in Inner Mongolia and Xinjiang, onshore wind turbine towers in Northeast China, load-bearing structures for alpine bridges, and import substitution for construction machinery operated in frigid zones.
Full-Service Support from GNEE Steel
With over 18 years of specialization in high-strength structural steel plate export business, GNEE maintains spot inventory exceeding 5,000 tons for 690 MPa-grade high-strength steel products. The company holds ISO9001 quality management certification, EU CE structural certification, SGS, BV and DNV marine inspection accreditation. Products are exported to over 40 countries including the European Union, Russia, Southeast Asia and Central Asia.
One-Stop Supporting Service
- Precision Custom Machining: CNC flame/plasma cutting, edge milling for weld preparation, bending and drilling precision machining to control embrittlement of heat-affected zones during cutting with dimensional tolerance ≤ ±1 mm. Magnetic Particle Testing (MT) for machined components is available on request.
- Complete Certification Document Issuance: European standard mill MTC, Chinese national factory test certificate, SGS third-party chemical composition / low-temperature Charpy impact re-inspection report, technical support for Welding Procedure Qualification (WPQ) documentation compilation.
- Integrated International Trade Delivery: FOB / CIF / DAP international trade quotation, moisture-proof anti-rust film packaging for marine shipment, complete customs declaration documents, container loading optimization, with 12-month anti-rust warranty for ocean transportation.
Free sample delivery with full quality inspection documents for small-batch trial orders; third-party on-site supervision available for bulk centralized procurement. Factory warehouse inspection is welcomed for on-site verification of spot inventory.
FAQ
Can S690Q replace S690QL for cold-region projects?
No, S690Q cannot directly replace S690QL for cold-region projects because it lacks certified low-temperature impact toughness.
Are direct mutual substitution allowed between Q690D and S690Q?
Direct mutual substitutions between Q690D and S690Q are generally technically feasible in function and strength, but not automatically permitted without explicit engineering verification and design review. While both share a minimum yield strength of 690 MPa and belong to the quenched and tempered high-strength structural steel category, they originate from different standards (GB/T and EN 10025-6) with subtle differences in impact testing temperatures and chemical controls.
Is post-weld heat treatment required for 30 mm thick S690QL welding fabrication?
Post-weld heat treatment (PWHT) is generally not required for 30 mm thick S690QL steel fabrication. PWHT can ruin the special quenched and tempered (Q+T) micro-structure and lower the strength of the steel, so it is usually avoided unless specifically demanded by a strict project code or design rule.
How to distinguish S690Q and S690QL spot steel plates on-site rapidly?
Quickly distinguishing S690Q and S690QL steel plates on-site is impossible via visual inspection or basic hardness testing, because they share identical mechanical strength and look the same. Rapid on-site identification requires checking mill test certificates (MTC), scanning plate heat numbers, or using a positive material analyzer (PMI).
