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Q690MC STRUCTURAL STEEL (TMCP)

TMCP Delivery | Grade Q690MC | Yield 690MPa | Impact 0°C 55J | High-Rise Building & Structural Steel 🔍 Q690MC Grade Lookup →

Product Overview

Q690MC 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 C provides impact properties at 0°C (longitudinal min. 55J, transverse min. 34J). 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.

Equivalent grades: Q690MC ↔ Q690C (previous domestic grade), EN 10025-6 S690QL (Europe), ASTM A709 Grade 690 (USA).

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)

Q690MC

Impact: 0°C (55J)

Yield: 690MPa

C: ≤0.18%

Si: ≤0.60%

Mn: ≤2.00%

P: ≤0.030%

S: ≤0.030%

TMCP Delivery | Grade C 0°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

Note: Q690MC is delivered in TMCP condition, offering refined grain structure and guaranteed impact toughness at 0°C (55J longitudinal). S690QL provides lower-temperature impact (-20°C) with quenched+tempered condition; ASTM A709 Grade 690 is commonly used for building and structural applications.

China Grade Comparison: Q690C vs Q690MC

Q690C (Previous)

As-rolled / Normalized

Yield: 690MPa (≤16mm)

Impact 0°C: 55J (Longitudinal)

C: ≤0.20%

P: ≤0.030%

S: ≤0.030%

Delivery: As-rolled or normalized

Q690MC (TMCP)

TMCP

Yield: 690MPa (≤16mm)

Impact 0°C: 55J (Longitudinal) / 34J (Transverse)

C: ≤0.18% (lower carbon)

Mn: ≤2.00%

Cr: ≤1.00%

P: ≤0.030%

S: ≤0.030%

Delivery: TMCP, refined grain, superior weldability, guaranteed 0°C toughness

Key Advantages

Ultra-High Strength

Min yield 690MPa, tensile 770-940MPa (≤40mm). Enables lighter structural sections and reduced material consumption.

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.

Seismic-Resistant Structures

Earthquake-resistant building frames, energy dissipation structures, moment-resisting frames for enhanced safety.

Q690MC Chemical Composition

Chemical element composition of Chinese grade Q690MC 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 C 0.18 0.6 2.0 0.030 0.030 0.01~0.11 0.01~0.12 0.006~0.05 1.0 0.8 0.8 0.3 0.015 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%. For Q690MC (Q690M grade C), carbon max 0.18% applies.

Mechanical Properties

Upper yield strength ReH (MPa, min) & Tensile properties (Q690MC Grade C)

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 C (0°C)

Direction 0°C
Longitudinal 55
Transverse 34
Note: Thermomechanically rolled (TMCP) condition includes TMCP + tempered condition. If yield not obvious, use Rp0.2. For thickness >80mm, consult technical specifications. Elongation after fracture A% ≥14% applies.

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

Full Testing
Spectral analysis, tensile & impact, ultrasonic
MTC 3.1/3.2
Full traceability & EN10204 docs

Packaging & Logistics

Bundled with steel straps, waterproof wrapping, clear marking. FOB, CIF, CFR from major Chinese ports. Lead time: 25-35 days.

Request a Quote

Direct email: customize@cehesteel.com – reply within 2 hours.

Frequently Asked Questions

What is Q690MC?

TMCP low-alloy high-strength structural steel per GB/T 1591-2018, min yield 690MPa, grade C guarantees impact 55J at 0°C (longitudinal).

Is Q690MC suitable for high-rise buildings?

Yes, Q690MC is ideal for high-rise buildings, large-span venues, and seismic-resistant structures due to its ultra-high strength and excellent weldability.

Equivalent to S690QL?

Yes, comparable to EN 10025-6 S690QL and ASTM A709 Grade 690.

Difference Q690MC vs Q690C?

Q690MC features TMCP delivery for refined grain structure, superior weldability, and guaranteed 0°C impact with transverse requirements (34J).

What are the main building applications?

High-rise building structures, large-span stadiums, exhibition centers, industrial plants, and seismic-resistant steel frames.