What Is S690Q Steel?
S690Q (material number 1.8931) is a European standard quenched and tempered (QT) fine-grain high-yield structural steel regulated under EN 10025-6. It delivers a minimum yield strength of 690 MPa for plate thicknesses 3–50 mm, with guaranteed Charpy V-notch impact toughness at -20°C (30 J longitudinal).
Manufactured via water quenching + high-temperature tempering, S690Q balances ultra-high tensile strength, low-temperature ductility and moderate weldability, widely specified for heavy load-bearing structures including mobile crane booms, mining machinery, offshore wind foundations, drilling platforms and long-span bridges.
- S = Structural steel
- 690 = Minimum yield strength (MPa) for thickness ≤50 mm
- Q = Quenched and tempered delivery condition, Charpy impact test requirement at -20°C
Stop over-engineering with mild steel. S690Q can cut your structural weight by 30–50% – but only if you choose the right grade, thickness, and heat treatment. One wrong specification may cost you 20% more in fabrication or risk brittle failure. Get a free technical consultation with our engineers to verify your design requirements – no obligation, just expert advice.
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Key Engineering Advantages of S690Q
- Ultra-high yield strength cuts structural weight by 30–50% vs S355JR mild steel, lowering logistics and foundation loads
- Controlled QT heat treatment delivers balanced strength and guaranteed -20°C low-temperature toughness
- Fine grain microstructure improves fatigue resistance for cyclic load machinery (cranes, mining vehicles)
- Consistent through-thickness mechanical performance for thick plates up to 150 mm
Chemical composition % of steel S690Q (1.8931): 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 0.025 | max 0.015 | 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 |
CEV directly predicts welding cold crack susceptibility, mandatory for welding procedure design:
- Thickness 3–50 mm: CEV ≤ 0.65
- Thickness 50–100 mm: CEV ≤ 0.77
GNEE STEEL production maintains actual CEV 0.59–0.73, below standard upper limits for improved weld performance.
mechanical properties of grade EN10025-6 S690Q
|
|
Minimum yield strength – ReH |
Tensile strength Rm |
Minimum elongation – A |
||||
|
Steel grade |
Nominal thickness |
Nominal thickness |
|||||
|
|
>3 |
>50 |
>100 |
>3 |
>50 |
>100 |
|
|
S690Q |
690 |
650 |
630 |
770-940 |
760-930 |
710-900 |
14 |
Charpy V-notch Impact
| Grade | Impact Test |
|---|---|
| S690Q | -20°C ≥30J |
| S690QL | -40°C ≥30J |
| S690QL1 | -60°C ≥30J |
Equivalent grades of steel S690Q (1.8931)
| EN 10025-6 | ASTM | DIN |
|---|---|---|
| S690Q | ASTM A514 Grade Q/F | StE690V |
Warning! Only for reference
S690q Plate Price
| Thickness | Reference Export Price |
|---|---|
| 6-20 mm | USD 850-1050/Ton |
| 20-50 mm | USD 900-1150/Ton |
| 50-100 mm | USD 1000-1300/Ton |
| >100 mm | USD 1200-1600/Ton |
Actual prices depend on thickness, quantity, ultrasonic testing requirements, delivery condition and destination port.
S690Q Steel Plate Thickness Tolerance
| Thickness Range | Tolerance Class A |
|---|---|
| 3-8 mm | ±0.3 mm |
| 8-15 mm | ±0.4 mm |
| 15-25 mm | ±0.5 mm |
| 25-40 mm | ±0.6 mm |
| 40-60 mm | ±0.8 mm |
S690Q plates are normally supplied according to EN 10029 Class A or tighter tolerances upon request.
Can S690Q be supplied in 120mm thickness?
Available Dimensions
| Item | Range |
|---|---|
| Thickness | 4-150 mm |
| Width | 1500-4000 mm |
| Length | 3000-18000 mm |
| Weight | Up to 25 Tons/Plate |
What is the difference between S690QL and S690Q?
The Core Difference: Low-Temperature Toughness
- S690Q: Minimum impact toughness tested at -20°C (30J average). → Typical Use: Cranes in temperate climates, quarry equipment.
- S690QL: Certified for -40°C and below (≥40J impact toughness). → Critical Use: Arctic pipelines, offshore platforms, mining vehicles in Siberia.
Misapplication Risk: Using S690Q below -20°C risks brittle fracture
S690Q Steel for Heavy Equipment
S690Q is specified for all structures subjected to extreme static and cyclic loads, enabling lightweight design with thinner cross-sections to reduce transport, foundation and raw material costs.
- Heavy Construction & Lifting Equipment
- Offshore & Energy Infrastructure
- Civil Structural Engineering
- Mining processing equipment
- pressure vessel support frames
- heavy transport vehicle chassis
Core Welding Performance of S690Q Steel
S690Q is weldable per EN 1011-2 arc welding specifications, but classified as limited weldability high-strength QT steel due to high carbon equivalent. Weld cracking risk rises with plate thickness and restrained joint geometry.
Primary Cold Cracking Root Causes
- High diffusible hydrogen trapped in weld metal
- High residual tensile stress concentrated at weld toes
- Brittle heat-affected zone (HAZ) martensitic microstructure
GNEE Steel Capabilities
- Consumables: Supply of low-hydrogen basic electrodes (≤5 ml/100g hydrogen) matched to S690Q
- Preheating rule: Technical guidance for thickness ≤50 mm ≥100°C; >50 mm ≥150°C; interpass temperature 150–250°C
- Heat input control: Professional welding procedure advice to prevent HAZ grain coarsening and toughness loss
- Post-weld treatment: Stress relief annealing (max 600°C, short hold time) available for highly restrained thick sections; full post-weld tempering is prohibited as it invalidates factory QT properties
- Cutting services: Water-jet cutting (up to 250mm) preferred for fatigue-critical structures; flame cutting (up to 500mm) for ultra-thick plates; laser cutting (up to 100mm) for high precision (±0.1mm)
- Fabrication support: 65 sets of automatic welding equipment and 6 large-scale industrial furnaces for integrated processing – cutting, bending, welding, drilling, grinding and painting – delivering semi-finished or finished components ready for assembly
Why Choose GNEE Steel For S690Q Plates?
- EN 10025-6 certified production
- Thickness up to 150 mm
- UT testing available (EN 10160, ASTM A578)
- Cutting, drilling and welding fabrication services
- Third-party inspection (SGS, BV, TUV)
- Fast global export delivery
Urgent project? We keep 500+ tons of S690Q in stock – from 6mm to 120mm – ready for immediate dispatch to major ports worldwide. No mill rolling wait time, no minimum order quantity for trial orders. Contact our export team today to check real-time inventory and get a firm delivery date before your competitor does.
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FAQ
What is the difference between S355 and S690 steel?
The S690 steel grade exhibits a Rockwell C hardness that is 23% higher than the S355 steel grade, which is consistent with the higher yield stress of the S690 steel grade.
Can S690Q be welded?
Yes. S690Q can be welded using low-hydrogen consumables and appropriate preheating procedures.
Is S690Q equivalent to ASTM A514?
They are similar high-strength quenched and tempered steels, but mechanical properties and specifications should be verified before substitution.
What is the maximum thickness of S690Q plate?
EN 10025-6 covers thicknesses up to 150 mm, while heavier sections may be available upon request.
