High-strength quenched and tempered structural steel plates with a minimum yield strength of 690 MPa serve as core materials for lightweight heavy-load engineering, construction machinery, offshore engineering and exported steel structure projects. S690Q (EN 10025-6 European standard high-strength steel) and Q690D (GB/T 16270 Chinese national standard high-strength steel) are the two most mainstream 690MPa-grade quenched and tempered steel plates available on the global market.
What is S690Q High-Strength Steel Plate? (EU Standard EN 10025-6)
S690Q is a quenched and tempered (Q+T) high-strength structural steel manufactured to EN 10025-6:2019, the harmonized European standard for hot rolled structural steel products.
Grade Code Explanation
S: Structural steel
690: Minimum yield strength ≥ 690 MPa (based on plate thickness ≤ 50 mm)
Q: Quenched and tempered delivery condition (Q+T heat treatment)
The absence of suffix "L" denotes a Charpy V-notch impact test temperature of −20 °C
What is Q690D High-Strength Steel Plate? (Chinese National Standard GB/T 16270)
Q690D is a domestic quenched and tempered high-strength structural steel conforming to GB/T 16270-2009 High Strength Quenched and Tempered Structural Steel Plates for Mechanical Engineering. It is the most commonly used high-strength steel grade for heavy machinery fabrication across China.
Grade Code Explanation
Q: Yield strength
690: Specified minimum yield strength of 690 MPa
D: Charpy V-notch impact test conducted at −20 °C
Established in 2008, GNEE Steel is a professional exporter and comprehensive service provider of high-strength steel plates. Our core product range covers pressure vessel steel, offshore structural steel, quenched and tempered high-tensile structural steel and abrasion-resistant steel plates, backed by 18 years of experience in steel plate fabrication and international trading. If you are engaged in European engineering tender procurement for S690Q steel plate or bulk procurement of Q690D for domestic heavy machinery projects, please submit your drawings, plate thickness, operating temperature and required order quantity. Our professional engineering team will deliver a complimentary material grade optimization proposal and formal mill quotation within two working hours.
S690Q Q690D High Strength Structural Steel Plate Specification
|
Type |
S690Q Q690D High Strength Structural Steel Plate |
|
Thickness |
6-150mm |
|
Length |
3000mm, 5800mm, 6000mm, 12000mm,etc |
|
Width |
1000mm,1219mm,1500mm,1800mm,2000mm,2500mm,3000mm,etc |
|
Standard |
EN 10025-6; GB/T 16270 |
|
Edge |
Mill Edge/ Silt Edge |
|
Quality |
Mill Test Certificate supplied with the shipment ,third part inspection is acceptable |
|
Grade |
S690Q, Q690D |
S690Q vs Q690D High Strength Steel Plate Chemical Composition
| Element | C | Si | Mn | P | S | Mo | Ni | V |
|---|---|---|---|---|---|---|---|---|
| S690Q | 0.20 | 0.60 | 1.70 | 0.025 | 0.020 | 0.70 | 2.00 | No mandatory requirement |
| Q690D | 0.21 | 0.60 | 1.80 | 0.030 | 0.025 | 0.50 | Unlimited | 0.12 |
S690Q vs Q690D High Strength Steel Plate Mechanical Property
| Mechanical Index | S690Q | Q690D |
|---|---|---|
| Yield Strength ReH | ≥690MPa | ≥690MPa |
| Tensile Strength Rm | 770 ~ 940MPa | 770 ~ 940MPa |
| Elongation A | ≥14% | ≥14% |
| -20℃ Charpy V-notch Impact Energy | ≥40J (Longitudinal) | ≥34J (Longitudinal) |
| Maximum Carbon Equivalent Ceq | 0.65 | 0.63 |
S690Q vs Q690D Structural Steel Plate Standard System Difference
| Dimension | S690Q (EU Standard System) | Q690D (Chinese National Standard System) |
|---|---|---|
| Top Standard System | EU EN Harmonized Standard | GB National Standard for Mechanical Steel |
| Supporting Certification | CE 1090 structural steel certification | National steel mill quality certification |
| Customs Clearance for EU | Direct use of EN MTC for customs declaration | Need third-party laboratory re-inspection for performance verification |
| Equivalent Low-Temperature Grade | S690QL (-40℃ impact) | Q690E (-40℃ impact) |
| Acceptance Basis for Inspection | EN 10160, EN 10045 Impact Test Standard | GB/T 229 Impact Test, GB/T 228 Tensile Test |
Comparative Analysis of Low-Temperature Impact Toughness and Service Temperature
Both S690Q and Q690D are designed for applications requiring low-temperature impact resistance at −20 °C, but differ significantly in their minimum guaranteed Charpy impact energy values.
- S690Q requires a minimum longitudinal Charpy impact energy of 40 J at −20 °C, featuring more stringent toughness acceptance standards. It exhibits a lower ductile-to-brittle transition temperature under equivalent low-temperature conditions and provides enhanced brittle fracture resistance for plates with thickness exceeding 50 mm.
- Q690D specifies a minimum impact energy of 34 J at −20 °C. Nevertheless, domestic factory inspection typically controls the actual impact energy above 47 J to ensure adequate engineering safety margin, ensuring stable service performance at ambient temperatures of −20 °C and above.
Service Temperature Selection Principles
Domestic projects with stable ambient temperatures above −20 °C: Q690D offers optimal cost-effectiveness.
European export projects operating outdoors at sustained temperatures around −20 °C: S690Q is mandatory to meet EU structural anti-fracture design specifications.
Service temperatures below −20 °C (e.g., extreme low-temperature environments of −40 °C): Grade upgrade to S690QL (EU standard) or Q690E (Chinese national standard) is required.
S690Q vs Q690D Steel Plate Weldability and Fabrication Performance
General Welding Requirements for Q690D and S690Q Steel Plates
Both are quenched and tempered high-strength structural steels with a high carbon equivalent and high cold cracking susceptibility. The process specifications are as follows:
- Preheating requirement: Uniform overall preheating to 100°C–150°C before welding.
- Welding consumable selection: Use low-hydrogen or ultra-low-hydrogen welding electrodes (e.g., E9018-G) and implement strict control over diffusible hydrogen content in the weld metal.
- For plate thickness exceeding 50 mm: Post-weld stress relief annealing at 620°C–650°C is recommended.
Fabrication Performance Comparison: Q690D vs S690Q Structural Steel Plate
Q690D Structural Steel Plate
Its lower carbon equivalent and grain refinement effect induced by vanadium (V) alloying elements lower the risk of welding cold cracking and provide a broader welding process window for complex on-site field welding. The steel features excellent cutting, bending and cold forming performance, making it ideal for secondary cutting and forming of small and medium-sized structural parts.
S690Q Structural Steel Plate
High molybdenum (Mo) alloy addition improves the steel's hardenability, which requires stringent temperature control during welding of thick plates. The material has consistent integral forming performance and is highly applicable for fabrication of large integral structural members for standardized export steel structures. Frequent cold bending and repeated reworking are not advised.
S690Q vs Q690D High Strength Plate Typical Application Scenarios
S690Q Typical Applications
- Heavy-duty truck chassis, crane main boom, mobile lifting equipment structural parts;
- Steel structure bridges, offshore auxiliary modules exported to Europe and Australia;
- Engineering projects requiring CE structural steel certification bidding;
- Large port machinery heavy load bearing beam for overseas terminals.
Q690D Typical Applications
- Large excavator arm, crawler crane turntable, mining dump truck frame;
- Onshore wind power tower flange and reinforcing beam, heavy factory load-bearing steel beam;
- Municipal engineering heavy steel structure, mining crushing equipment frame;
- Conventional steel structure lightweight transformation projects with cost control requirements.
GNEE Steel's Comprehensive Advantages in Supplying S690Q and Q690D Steel Plates
One‑Stop Supply for Both Grades
We maintain stock of Q690D plates and supply custom‑manufactured S690Q steel plates concurrently, satisfying one‑stop procurement demands for mixed domestic and international projects.
Rigorous Quality Control & Document Support
All steel plates are delivered with original Mill Test Certificates (MTC), chemical composition optical emission spectroscopy reports, tensile test reports, low‑temperature Charpy impact test reports and ultrasonic testing reports. Every plate is marked with a traceable heat number.
Flexible Lead Times
Q690D stock plates: Shipment within 3‑7 calendar days
S690Q custom orders: In close alignment with steel mill production plans, lead time is reliably kept within 15‑20 working days
Kindly submit your engineering drawing dimensions, service temperature, destination country and order quantity. Our team will furnish a customized material‑selection proposal (including cost comparison) and formal Proforma Invoice (PI) within one working day, helping you prevent engineering losses arising from incorrect material grade selection.
FAQ
What are the equivalent grades of steel to Q690D steel?
Equivalent international grades for China's Q690D high-strength structural steel (which features a minimum yield strength of 690 MPa and -20°C impact toughness) include Europe's S690QL / S690Q (EN 10025-6), International E690 (ISO), Japan's JFE HITEN 780LE, and similar high-yield American equivalents like ASTM A514 Grade Q.
What is the hardness of S690Q steel?
The typical Brinell hardness of S690Q structural steel (conforming to EN 10025-6) ranges approximately from 210 HBW to 278 HBW, depending on the thickness of the steel plate.
What are the material properties of S690Q steel?
S690Q is a quenched and tempered high-yield structural steel defined under the EN 10025-6 standard. It provides a minimum yield strength of 690 MPa for thicknesses up to 50 mm, a tensile strength range of 770–940 MPa, a minimum elongation of 14%, and good impact toughness at -20°C.
