Q800D High Strength Structural Steel Plate

Strictly Compliant with GB/T 16270-2009 | Quenched & Tempered State | Thickness Up to 150mm | Excellent Low-Temperature Toughness (-20℃) | Custom Sizes Available

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Product Overview

Q800D 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).

Q800D is smelted by oxygen converter or electric furnace, with strict control of chemical composition and carbon equivalent (CEV ≤0.55%), ensuring excellent high strength and superior low-temperature toughness (-20℃ 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 low-temperature stability (-20℃ working environment).

According to GB/T 16270-2009 Appendix A, Q800D has approximate equivalent grades in European standards, and is the preferred material for high-strength structural components working in low-temperature environments (-20℃) 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 Q800D grade with -20℃ 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
Q800D ≤50 0.20 0.80 2.00 0.025 0.015 0.50 1.50 2.00 0.70 0.0050 0.12 0.06 0.05 0.72
>50~100 0.20 0.80 2.00 0.025 0.015 0.50 1.50 2.00 0.70 0.0050 0.12 0.06 0.05 0.82
>100~150 0.20 0.80 2.00 0.025 0.015 0.50 1.50 2.00 0.70 0.0050 0.12 0.06 0.05 -

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: Q800D has strict P/S control (P≤0.020%, S≤0.010%) to ensure low-temperature toughness (-20℃) and structural stability.
Note 5: Q800D 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 ≤50mm >50~100mm All Thickness -20℃ (Longitudinal)
Q800D 800 740 - 840~1000 800~1000 13 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: Q800D impact test temperature is -20℃ (KV2≥34J), reflecting excellent low-temperature toughness (GB/T 16270-2009 standard requirement).
Note 6: Q800D 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 Q800D are as follows:

Property Q800D (GB/T 16270-2009)
China | Quenched & Tempered		 S890QL (EN 10025-6:2004)
EU | Quenched & Tempered		 ASTM A514 Gr.Q (ASTM A514)
US | Quenched & Tempered
Min Yield Strength (MPa) 800 (≤50mm) 890 (≤100mm) 690 (≤100mm)
Tensile Strength (MPa) 870~1040 960~1100 760~895
Min Elongation (%) 12 10 15
Impact Test Temperature (°C) -20℃ (KV2≥34J) -40℃ (KV≥40J) -40℃ (KV≥27J)
Max Carbon Content (%) 0.20 0.20 0.21
Carbon Equivalent CEV ≤ 0.65~0.83 (by thickness) 0.55 0.50
Max Thickness (mm) 150 150 100
Main Applications High-load engineering machinery, heavy structural components in low-temperature regions (-20℃) High-rise building structures, heavy crane components in cold regions Ultra-high strength structural components in low-temperature environments

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. Q800D is equivalent to S890QL in EN standard in terms of strength grade and has good low-temperature toughness (-20℃).

Application Cases

High Load Engineering Machinery with Q800D Steel

High Load Engineering Machinery

Heavy excavator arms, large crane booms, hydraulic support components and mining machinery in cold regions. Q800D's ultra-high strength (yield ≥800MPa) and excellent -20℃ low-temperature toughness meet the extreme load requirements of heavy engineering machinery in cold environments.

Heavy Building Structures with Q800D Steel

Heavy Building Structures

Large-span bridge structural components, high-rise building core columns, large stadium steel structures and industrial factory heavy load-bearing beams in cold regions. Q800D's high strength-to-weight ratio and -20℃ toughness reduce structural weight while ensuring safety in low-temperature environments.

Port Heavy Machinery with Q800D Steel

Port Heavy Machinery

Large port cranes, ship unloaders, container gantry cranes and bulk cargo handling equipment in coastal areas. Q800D's ultra-high strength, wear resistance, structural stability and -20℃ toughness meet the long-term heavy-duty operation requirements in low-temperature port environments.

Frequently Asked Questions

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

GB/T 16270-2009 has the following key updates: 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; 3. Adding quality grade C/F and adjusting composition and performance; 4. Canceling bending performance requirements and adding CEV carbon equivalent index; 5. Deleting delivery states such as normalizing and controlled rolling, and only retaining quenched + tempered state; 6. Adding Q800D grade with -20℃ low-temperature impact requirement and Z-direction performance requirement.

Why is Q800D suitable for low-temperature (-20℃) applications? +

Q800D is specially designed for low-temperature environments for the following reasons: 1. Strict control of impurity elements (P≤0.020%, S≤0.010%) to avoid cold brittleness; 2. CEV carbon equivalent ≤0.55% (for thickness ≤50mm) to ensure weldability and low-temperature toughness; 3. Mandatory -20℃ impact test (KV2≥34J) to verify low-temperature performance; 4. Addition of grain refinement elements (Nb/Ti/V/Al) to refine grains and improve low-temperature toughness; 5. Z-direction performance requirement (Z15/Z25/Z35) for thickness ≥15mm to prevent lamellar tearing in low-temperature welding.

What are the welding requirements for Q800D steel plates? +

Q800D welding key points: 1. Preheating temperature: 100~200℃ (adjust according to thickness, ≥50mm needs 150~200℃); 2. Interpass temperature ≤250℃ to avoid overheating affecting toughness; 3. Recommended welding materials: matching strength grade (yield ≥800MPa) low-hydrogen electrodes/wires (such as E11018-G, ER110S-G); 4. Post-weld heat treatment: stress relief annealing (580~620℃) is recommended for all thicknesses to reduce welding stress; 5. Welding process: use ultra-low heat input, multi-layer multi-pass welding to reduce welding stress and deformation.

What is the difference between Q800D and Q800C/Q800E/Q800F grades? +

The core difference lies in low-temperature impact requirements: 1. Q800C: 0℃ impact (KV2≥34J); 2. Q800D: -20℃ impact (KV2≥34J); 3. Q800E: -40℃ impact (KV2≥34J); 4. Q800F: -60℃ impact (KV2≥34J) (strictest). In addition, Q800D has stricter P/S control (P≤0.020%, S≤0.010%) than Q800C (P≤0.025%, S≤0.015%), and mandatory Z-direction performance requirement for thickness ≥15mm, making it suitable for low-temperature (-20℃) applications in harsh environments.

What are the customization capabilities of Q800D steel plates? +

CEHE Steel provides full customization for Q800D: 1. Size customization: thickness 6~100mm, 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), surface quality grade (A/B/C/D); 3. Processing customization: flame cutting, plasma cutting, beveling, shot blasting, painting, anti-rust oil coating; 4. Certification customization: provide mill test certificate (MTC) according to EN 10204 3.1/3.2, third-party inspection (SGS/BV/ABS) report; 5. Delivery cycle: stock for common sizes (5-7 days), customized production (20-30 days).

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