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Q550ME STRUCTURAL STEEL (TMCP)

TMCP Delivery | Grade Q550ME | Yield 550MPa | Impact -40°C 31J | Extreme Low-Temperature Ultra-High Strength Steel 🔍 Q550ME Grade Lookup →

Product Overview

Q550ME 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 extreme low-temperature toughness. The quality grade E provides impact properties at -40°C (longitudinal min. 31J, transverse min. 20J). With minimum yield strength of 550MPa (≤16mm), it delivers superior strength for arctic engineering, offshore structures, and critical building applications requiring exceptional performance in severe cold environments.

Equivalent grades: Q550ME ↔ Q550E (previous domestic grade), EN 10025-4 S550MC (Europe), ASTM A656 Grade 80 (USA).

International Grade Comparison（EN vs GB vs ASTM）

Europe (EN 10025-4)

S550MC

Impact: 0°C (40J)

Yield: 550MPa

C: ≤0.16%

Si: ≤0.60%

Mn: ≤2.00%

P: ≤0.025%

S: ≤0.020%

China (GB/T 1591)

Q550ME

Impact: -40°C (31J)

Yield: 550MPa

C: ≤0.18%

Si: ≤0.60%

Mn: ≤2.00%

P: ≤0.025%

S: ≤0.020%

TMCP Delivery | Grade E -40°C Impact

USA (ASTM A656)

Gr.80

Impact: -20°C (optional)

Yield: 550MPa min

C: ≤0.18%

Si: ≤0.60%

Mn: ≤1.80%

P: ≤0.025%

S: ≤0.020%

Note: Q550ME is delivered in TMCP condition, offering refined grain structure and guaranteed impact toughness at -40°C. S550MC offers similar yield strength with 0°C impact (40J); ASTM A656 Grade 80 provides comparable strength (550MPa min) with optional -20°C impact.

China Grade Comparison: Q550E vs Q550ME

Q550E (Previous)

As-rolled / Normalized

Yield: 550MPa (≤16mm)

Impact -40°C: 31J (Longitudinal)

C: ≤0.20%

P: ≤0.025%

S: ≤0.020%

Delivery: As-rolled or normalized

Q550ME (TMCP)

TMCP

Yield: 550MPa (≤16mm)

Impact -40°C: 31J (Longitudinal) / 20J (Transverse)

C: ≤0.18% (lower carbon)

Mn: ≤2.00%

P: ≤0.025%

S: ≤0.020%

Delivery: TMCP, refined grain, superior weldability, guaranteed -40°C toughness

Key Advantages

Ultra-High Strength

Min yield 550MPa, tensile 670-830MPa (≤40mm).

-40°C Impact Toughness

Guaranteed KV2 31J at -40°C (Longitudinal).

Excellent Weldability

Optimized TMCP process, low carbon equivalent.

Applications

Building Structures

High-rise buildings, stadiums, industrial plants, arctic and cold-region construction requiring -40°C impact reliability.

Engineering Structures

Bridge girders, transmission towers, offshore platforms, polar infrastructure, heavy machinery in extreme cold environments.

Q550ME Chemical Composition

Chemical element composition of Chinese grade Q550ME low alloy high strength structural steel
Current manufacturing execution standard: GB/T 1591-2018

Grade Quality C ≤ Si ≤ Mn ≤ P ≤ S ≤
Q550M E 0.18 0.60 2.00 0.025 0.020
Nb V Ti Cr ≤ Ni ≤ Cu ≤ Mo ≤ N ≤ B ≤ Als ≥
0.01-0.11 0.01-0.12 0.006-0.05 0.8 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)

≤16mm 16-40mm 40-63mm 63-80mm 80-100mm 100-120mm
550 540 530 510 500 —

Tensile strength Rm (MPa)

≤40mm 40-63mm 63-80mm 80-100mm 100-120mm
670-830 620-810 600-790 590-780 —

Elongation A% (min): 16%

Impact KV2 (J) min – Quality E (-40°C)

Direction -40°C
Longitudinal 31
Transverse 20
Note: Thermomechanically rolled (TMCP) condition includes TMCP + tempered condition. If yield not obvious, use Rp0.2. For thickness >100mm, consult technical specifications.

Size & Specification

Product Thickness (mm) Width (mm) Length (mm)
Plate 3-100 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 Q550ME?

TMCP low-alloy high-strength steel per GB/T 1591-2018, min yield 550MPa, grade E guarantees impact 31J at -40°C (longitudinal).

Equivalent to S550MC?

Yes, comparable to EN 10025-4 S550MC and ASTM A656 Grade 80.

Difference Q550ME vs Q550E?

Q550ME features TMCP delivery for refined grain structure, superior weldability, and guaranteed -40°C impact with transverse requirements (20J).

Typical applications?

Heavy engineering structures (bridges, cranes, mining equipment), arctic infrastructure, high-rise buildings requiring ultra-high strength and -40°C toughness.