Q690MD STRUCTURAL STEEL (TMCP)
Product Overview
Q690MD is a Chinese grade low-alloy high-strength structural steel conforming to GB/T 1591-2018 standard. Delivered in thermomechanically rolled (TMCP) condition, it offers refined grain structure, excellent weldability, and guaranteed low-temperature toughness. The quality grade D provides impact properties at -20°C (longitudinal min. 47J, transverse min. 27J). With minimum yield strength of 690MPa (≤16mm), it delivers superior strength-to-weight ratio, enabling lighter and more efficient structural designs for modern construction projects in cold environments.
International Grade Comparison
Europe (EN 10025-6)
S690QL
Impact: -20°C (40J)
Yield: 690MPa
C: ≤0.19%
Si: ≤0.80%
Mn: ≤1.70%
P: ≤0.025%
S: ≤0.015%
Quenched+Tempered
China (GB/T 1591)
Q690MD
Impact: -20°C (47J)
Yield: 690MPa
C: ≤0.18%
Si: ≤0.60%
Mn: ≤2.00%
P: ≤0.030%
S: ≤0.025%
TMCP Delivery | Grade D -20°C Impact
USA (ASTM A709)
Gr. 690
Impact: -20°C (optional)
Yield: 690MPa min
C: ≤0.20%
Si: ≤0.55%
Mn: ≤1.60%
P: ≤0.025%
S: ≤0.020%
Quenched & Tempered
China Grade Comparison: Q690D vs Q690MD
Q690D (Previous)
Yield: 690MPa (≤16mm)
Impact -20°C: 47J (Longitudinal)
C: ≤0.20%
P: ≤0.030%
S: ≤0.030%
Delivery: As-rolled or normalized
Q690MD (TMCP)
Yield: 690MPa (≤16mm)
Impact -20°C: 47J (Longitudinal) / 27J (Transverse)
C: ≤0.18% (lower carbon)
Mn: ≤2.00%
Cr: ≤1.00%
P: ≤0.030%
S: ≤0.025% (tighter control)
Delivery: TMCP, refined grain, superior weldability, guaranteed -20°C toughness
Key Advantages
Ultra-High Strength
Min yield 690MPa, tensile 770-940MPa (≤40mm). Enables lighter structural sections and reduced material consumption.
-20°C Impact Toughness
Guaranteed KV2 47J at -20°C (Longitudinal), ideal for cold-region construction.
High-Rise Building Performance
Excellent strength-to-weight ratio ideal for high-rise structures, large-span venues, and seismic-resistant designs.
Excellent Weldability
Optimized TMCP process, low carbon equivalent, suitable for complex welded structures.
Applications – Building & Structural Engineering
High-Rise Buildings
Skyscrapers, super high-rise structures, commercial complexes, residential towers requiring high strength-to-weight ratio and seismic performance.
Large-Span Structures
Stadiums, exhibition centers, airport terminals, convention halls – achieving longer spans with reduced steel weight.
Industrial Structures
Heavy industrial plants, steel mills, power plants, factory buildings requiring high load-bearing capacity.
Heavy Engineering
Cranes, mining equipment, excavators, heavy machinery requiring ultra-high strength steel.
Cold-Region Structures
Arctic infrastructure, cold-climate buildings, structures requiring reliable performance at -20°C.
Seismic-Resistant Structures
Earthquake-resistant building frames, energy dissipation structures, moment-resisting frames for enhanced safety.
Q690MD Chemical Composition
Chemical element composition of Chinese grade Q690MD low alloy high strength structural steel
Current manufacturing execution standard: GB/T 1591-2018
| Steel grade | Quality | C ≤ | Si ≤ | Mn ≤ | P ≤ | S ≤ | Nb | V | Tiᵇ | Cr ≤ | Ni ≤ | Cu ≤ | Mo ≤ | N ≤ | B ≤ | Alsᶜ ≥ | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Q690M | D | 0.18 | 0.6 | 2.0 | 0.030 | 0.025 | 0.01~0.11 | 0.01~0.12 | 0.006~0.05 | 1.0 | 0.8 | 0.8 | 0.3 | 0.025 | 0.004 | 0.015 | ||
Notes: The steel shall contain at least one grain-refining element (Al, Nb, V, Ti) with content not less than lower limit. All-aluminum (Alt) min 0.02% if substituted. For structural steel and bars, P/S can increase by 0.005%. Ti can be as high as 0.2%.
Mechanical Properties
Upper yield strength ReH (MPa, min) – Q690MD Grade D
| Thickness (mm) | ≤16 | >16~40 | >40~63 | >63~80 | >80~100 | >100~120 |
|---|---|---|---|---|---|---|
| Yield (min) | 690 | 680 | 670 | 650 | — | — |
Tensile strength Rm (MPa)
| Thickness | ≤40mm | >40~63mm | >63~80mm | >80~100mm | >100~120mm |
|---|---|---|---|---|---|
| Rm (MPa) | 770-940 | 750-920 | 730-900 | — | — |
Elongation A% (min): 14%
Impact KV2 (J) min – Quality D (-20°C)
| Direction | -20°C |
|---|---|
| Longitudinal | 47 |
| Transverse | 27 |
Size & Specification
| Product | Thickness (mm) | Width (mm) | Length (mm) |
|---|---|---|---|
| Plate | 3-80 | 1000-4000 | 3000-18000 |
| Sheet/Coil | 1.5-20 | 900-2000 | Coil or cut length |
Custom sizes and cutting available upon request.
Customizable Options
Laser/plasma cutting, edge beveling, shot blasting, priming, third-party inspection, custom marking.
Quality Assurance
Spectral analysis, tensile & impact, ultrasonic
Full traceability & EN10204 docs
Packaging & Logistics
Request a Quote
Direct email: customize@cehesteel.com – reply within 2 hours.
Frequently Asked Questions
TMCP low-alloy high-strength structural steel per GB/T 1591-2018, min yield 690MPa, grade D guarantees impact 47J at -20°C (longitudinal).
Yes, Q690MD is ideal for high-rise buildings, large-span venues, and seismic-resistant structures due to its ultra-high strength and excellent low-temperature toughness.
Yes, comparable to EN 10025-6 S690QL and ASTM A709 Grade 690.
Q690MD features TMCP delivery for refined grain structure, superior weldability, and guaranteed -20°C impact with transverse requirements (27J).
High-rise building structures, large-span stadiums, exhibition centers, industrial plants, cold-region structures, and seismic-resistant steel frames.