Q550F High Strength Structural Steel Plate

Strictly Compliant with GB/T 16270-2009 | Quenched & Tempered State | Thickness Up to 150mm | Excellent Low-Temperature Toughness (-60℃) | Custom Sizes Available

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Product Overview

Q550F is a high strength structural steel plate specified in GB/T 16270-2009 High strength structural steel plates in the quenched and tempered condition standard, replacing the old GB/T 16270-1996 version. The product is delivered in quenched + tempered state, with a maximum applicable thickness of 150mm (expanded from the original 100mm).

Q550F is smelted by oxygen converter or electric furnace, with strict control of chemical composition and carbon equivalent (CEV ≤0.50%), ensuring excellent high strength and superior low-temperature toughness (-60℃ impact resistance). It is widely used in engineering machinery, construction structures, port machinery, bridge engineering and other fields that require high load-bearing capacity and ultra-low-temperature stability (-60℃ working environment).

According to GB/T 16270-2009 Appendix A, Q550F has approximate equivalent grades in European standards, and is the preferred material for high-strength structural components working in ultra-low-temperature environments (-60℃) in domestic and international engineering projects.

★ Key Standard Update:

GB/T 16270-2009 cancels the bending performance requirement, adds CEV carbon equivalent index, and deletes the delivery states of normalizing, normalizing+tempering and controlled rolling. It also defines Q550F grade with -60℃ low-temperature impact requirement and Z-direction performance requirement for thickness ≥15mm.

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Technical Specifications (GB/T 16270-2009)

All data is in accordance with the official GB/T 16270-2009 standard, the unit of chemical composition is mass fraction (wt%), and the mechanical properties are tested with transverse tensile samples and longitudinal impact samples.

Chemical Composition (wt%, Max) & Carbon Equivalent CEV

Grade Thickness mm C Si Mn P S Cu Cr Ni Mo B V Nb Ti CEV
Q550F ≤50 0.20 0.80 1.70 0.020 0.010 0.50 1.50 2.00 0.70 0.0050 0.12 0.06 0.05 0.65
>50~100 0.20 0.80 1.70 0.020 0.010 0.50 1.50 2.50 0.70 0.0050 0.12 0.06 0.05 0.77
>100~150 0.20 0.80 1.70 0.020 0.010 0.50 1.50 2.50 0.70 0.0050 0.12 0.06 0.05 0.83

Note 1: At least one grain refinement element (Nb/Ti/V/Al) shall be added, the minimum content of at least one element is 0.015% (Als for Al), or Alt can be used instead of Als with a minimum of 0.018%.
Note 2: CEV calculation formula (GB/T 16270-2009): CEV = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15.
Note 3: The chemical composition tolerance of finished steel plate complies with GB/T 222.
Note 4: Q550F has stricter P/S control (P≤0.015%, S≤0.008%) than Q550E to ensure ultra-low-temperature toughness (-60℃) and Z-direction performance.
Note 5: Q550F requires Z-direction performance test (Z15/Z25/Z35) for thickness ≥15mm to prevent lamellar tearing.

Mechanical Properties (GB/T 16270-2009)

Grade Yield Strength ReH (MPa) ≥ Yield Strength ReH (MPa) ≥ Yield Strength ReH (MPa) ≥ Tensile Strength Rm (MPa) Tensile Strength Rm (MPa) Elongation after Fracture A (%)  Impact Absorption Energy KV2 (J) 
≤50mm >50~100mm >100~150mm ≤100mm >100~150mm All Thickness -60℃ (Longitudinal)
Q550F 550 530 490 640~820 590~770 16 34

Note 1: When the yield phenomenon is not obvious, Rp0.2 is used instead of ReH.
Note 2: The impact energy is the arithmetic mean of three samples, one sample is allowed to be lower than the specified value but not less than 70% of the specified value.
Note 3: For plates with thickness 8~12mm, 75% of the specified impact value is required for 10×7.5×55mm auxiliary samples; for 6~8mm, 50% for 10×5×55mm auxiliary samples; no impact test for <6mm.
Note 4: Smelting method: oxygen converter/electric furnace; delivery state: quenched + tempered.
Note 5: Q550F impact test temperature is -60℃ (KV2≥34J), reflecting excellent ultra-low-temperature toughness (stricter than Q550E's -40℃ requirement).
Note 6: Q550F requires Z-direction performance test for thickness ≥15mm (Z15/Z25/Z35 grade optional) to ensure resistance to lamellar tearing.

International Standard Approximate Comparison

According to GB/T 16270-2009 Appendix A (informative appendix) and official international standard data, the approximate equivalent grades of Q550F are as follows:

Property Q550F (GB/T 16270-2009)
China | Quenched & Tempered		 S550QL2 (EN 10025-6:2004)
EU | Quenched & Tempered		 ASTM A514 Gr.Q (ASTM A514)
US | Quenched & Tempered
Min Yield Strength (MPa) 550 (≤50mm) 550 (≤100mm) 690 (≤100mm)
Tensile Strength (MPa) 630~830 630~830 760~895
Min Elongation (%) 16 16 15
Impact Test Temperature (°C) -60℃ (KV2≥34J) -70℃ (KV≥40J) -40℃ (KV≥27J)
Max Carbon Content (%) 0.18 0.20 0.21
Carbon Equivalent CEV ≤ 0.48~0.53 (by thickness) 0.50 0.50
Max Thickness (mm) 150 150 100
Main Applications Extreme ultra-low-temperature engineering machinery, polar region structural components Extreme ultra-low-temperature high-rise structures, antarctic cranes Ultra-low-temperature heavy structural components

Note: The above is the approximate comparison of performance indicators, and the specific application shall be subject to the official standard of each country and the technical requirements of the project. CEHE Steel can provide products complying with Chinese, European and American standards according to customer requirements. Q550F is equivalent to S550QL2 in EN standard in terms of ultra-low-temperature performance (-60℃).

Application Cases

Extreme Low-temperature Construction Machinery with Q550F Steel

Extreme Low-temperature Engineering Machinery

Excavator arms, crane booms, loader buckets and hydraulic support components used in extreme cold regions (-40℃~-60℃). Q550F's high strength-to-weight ratio and excellent ultra-low-temperature toughness meet the load requirements of machinery in antarctic/arctic environments.

Antarctic Region Bridge Structures with Q550F Steel

Antarctic Region Building Structures

Large-span bridge deck plates, high-rise building structural beams and columns in antarctic regions, steel structure workshops in extreme low-temperature areas. Q550F's excellent ultra-low-temperature toughness and stability adapt to harsh outdoor environments (-60℃).

Antarctic Port Machinery with Q550F Steel

Antarctic Port Machinery

Port cranes, container handlers, ship unloaders and hoisting equipment in antarctic ports. Q550F's high load-bearing capacity, wear resistance and ultra-low-temperature toughness meet the long-term heavy-duty operation requirements in extreme low-temperature environments (-60℃).

Frequently Asked Questions

What are the key updates of GB/T 16270-2009 compared to the old version for Q550F? +

For Q550F grade in GB/T 16270-2009, the key updates include: 1. Expanding the applicable thickness from 100mm to 150mm and deleting the steel strip specification; 2. Canceling Q420 grade and adding Q800/Q890/Q960 grades, while optimizing the mechanical property index of Q550 grade; 3. Adding quality grade C/F and adjusting composition and performance of Q550F; 4. Canceling bending performance requirements and adding CEV carbon equivalent index (≤0.48% for Q550F); 5. Deleting delivery states such as normalizing and controlled rolling, and only retaining quenched + tempered state for Q550F; 6. Adding Q550F grade with -60℃ ultra-low-temperature impact requirement and Z-direction performance requirement.

Why is Q550F suitable for ultra-low-temperature (-60℃) applications? +

Q550F is specially designed for ultra-low-temperature environments for the following reasons: 1. Strict control of impurity elements (P≤0.012%, S≤0.006%) to avoid cold brittleness, stricter than Q500F; 2. CEV carbon equivalent ≤0.48% (for thickness ≤50mm) to ensure weldability and low-temperature toughness while maintaining high strength; 3. Mandatory -60℃ impact test (KV2≥37J) to verify ultra-low-temperature performance (higher than Q500F's 34J); 4. Addition of grain refinement elements (Nb/Ti/V/Al) to refine grains and improve low-temperature toughness under high strength; 5. Z-direction performance requirement (Z15/Z25/Z35) for thickness ≥15mm to prevent lamellar tearing in low-temperature welding for Q550F.

What are the welding requirements for Q550F steel plates? +

Q550F welding key points (higher strength than Q500F, stricter process control): 1. Preheating temperature: 100~180℃ (adjust according to thickness, ≥50mm needs 120~180℃, higher than Q500F); 2. Interpass temperature ≤200℃ to avoid overheating affecting toughness and strength; 3. Recommended welding materials: matching strength grade (yield ≥550MPa) low-hydrogen electrodes/wires (such as E9018-G, ER90S-G); 4. Post-weld heat treatment: generally not required, but stress relief annealing (550~600℃) is recommended for thick plates or complex structures to avoid strength loss; 5. Welding process: use lower heat input (≤15kJ/mm), multi-layer multi-pass welding to reduce welding stress and deformation for Q550F.

What is the difference between Q550F and Q550C/Q550D/Q550E grades? +

The core difference lies in low-temperature impact requirements and strength control: 1. Q550C: 0℃ impact (KV2≥34J), yield strength ≥550MPa; 2. Q550D: -20℃ impact (KV2≥34J), yield strength ≥550MPa; 3. Q550E: -40℃ impact (KV2≥34J), yield strength ≥550MPa; 4. Q550F: -60℃ impact (KV2≥37J) (strictest), yield strength ≥550MPa. In addition, Q550F has stricter P/S control (P≤0.012%, S≤0.006%) than Q550E (P≤0.020%, S≤0.010%), and mandatory Z-direction performance requirement for thickness ≥15mm, making it suitable for ultra-low-temperature (-60℃) high-strength applications in arctic regions/polar engineering.

What are the customization capabilities of Q550F steel plates? +

CEHE Steel provides full customization for Q550F (high-strength ultra-low-temperature grade): 1. Size customization: thickness 6~150mm, width 1500~4000mm, length 3000~18000mm (can be cut to custom size); 2. Performance customization: Z-direction performance (Z15/Z25/Z35), impact energy upgrade (KV2≥40J at -60℃), surface quality grade (A/B/C/D); 3. Processing customization: flame cutting, plasma cutting, beveling, shot blasting, painting, anti-rust oil coating (special anti-corrosion for low-temperature environment); 4. Certification customization: provide mill test certificate (MTC) according to EN 10204 3.1/3.2, third-party inspection (SGS/BV/ABS) report for high-strength low-temperature performance; 5. Delivery cycle: stock for common sizes (3-5 days), customized production (18-28 days, slightly longer than Q500F due to stricter heat treatment).

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