Q620C High Strength Structural Steel Plate

Strictly Compliant with GB/T 16270-2009 | Quenched & Tempered State | Thickness Up to 150mm | Excellent Low-Temperature Toughness (0℃) | Custom Sizes Available

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Product Overview

Q620C 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).

Q620C 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 (0℃ 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 (0℃ working environment).

According to GB/T 16270-2009 Appendix A, Q620C has approximate equivalent grades in European standards, and is the preferred material for high-strength structural components working in low-temperature environments (0℃) 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 Q620C grade with 0℃ 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
Q620C	≤50	0.20	0.80	1.70	0.025	0.015	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	0.025	0.015	0.50	1.50	2.00	0.70	0.0050	0.12	0.06	0.05	0.77
	>100~150	0.20	0.80	1.70	0.025	0.015	0.50	1.50	2.00	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: Q620C has standard P/S control (P≤0.020%, S≤0.010%) to ensure low-temperature toughness (0℃) and structural stability.
Note 5: Q620C 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)
Grade	≤50mm	>50~100mm	>100~150mm	≤100mm	>100~150mm	All Thickness	0℃ (Longitudinal)
Q620C	620	580	560	700~890	650~830	15	47

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: Q620C impact test temperature is 0℃ (KV2≥34J), reflecting excellent low-temperature toughness (basic grade requirement in GB/T 16270-2009).
Note 6: Q620C 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 Q620C are as follows:

Property	Q620C (GB/T 16270-2009) China \| Quenched & Tempered	S620QL (EN 10025-6:2004) EU \| Quenched & Tempered	ASTM A514 Gr.S (ASTM A514) US \| Quenched & Tempered
Min Yield Strength (MPa)	620 (≤50mm)	620 (≤100mm)	690 (≤100mm)
Tensile Strength (MPa)	720~900	720~900	760~895
Min Elongation (%)	15	15	15
Impact Test Temperature (°C)	0℃ (KV2≥34J)	-20℃ (KV≥40J)	-40℃ (KV≥27J)
Max Carbon Content (%)	0.20	0.20	0.21
Carbon Equivalent CEV ≤	0.50~0.58 (by thickness)	0.55	0.50
Max Thickness (mm)	150	150	100
Main Applications	High-load engineering machinery, heavy structural components	High-rise building structures, heavy crane components	Ultra-high strength 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. Q620C is equivalent to S620QL in EN standard in terms of strength grade.

Application Cases

High Load Engineering Machinery

Heavy excavator arms, large crane booms, hydraulic support components and mining machinery. Q620C's ultra-high strength (yield ≥620MPa) and excellent toughness meet the extreme load requirements of heavy engineering machinery in normal temperature environments.

Heavy Building Structures

Large-span bridge structural components, high-rise building core columns, large stadium steel structures and industrial factory heavy load-bearing beams. Q620C's high strength-to-weight ratio reduces structural weight while ensuring safety.

Port Heavy Machinery

Large port cranes, ship unloaders, container gantry cranes and bulk cargo handling equipment. Q620C's ultra-high strength, wear resistance and structural stability meet the long-term heavy-duty operation requirements in port environments.

Frequently Asked Questions

What are the key characteristics of Q620C high-strength steel plate? +

Q620C is a grade of high-strength low-alloy structural steel with the following key characteristics: 1. Yield strength ≥620MPa, tensile strength 720~880MPa, ensuring high load-bearing capacity; 2. 0℃ impact test requirement (KV2≥34J) for good low-temperature toughness at mild cold environments; 3. CEV carbon equivalent ≤0.55% (for thickness ≤50mm) to guarantee excellent weldability; 4. Delivered in quenched + tempered state for uniform mechanical properties; 5. Applicable thickness range 6~100mm, suitable for heavy-duty engineering structures; 6. Strict control of impurity elements (P≤0.020%, S≤0.010%) to avoid material brittleness.

What are the typical application scenarios of Q620C steel plates? +

Q620C is widely used in high-stress engineering structures due to its high strength and good toughness: 1. Construction machinery: crane booms, excavator arms, bulldozer chassis, withstanding heavy loads and dynamic impacts; 2. Bridge engineering: main load-bearing components of medium-span steel bridges, reducing structural weight while ensuring safety; 3. Mining equipment: mine support frames, conveyor belt brackets, adapting to harsh working conditions; 4. Port machinery: container gantry cranes, ship unloaders, requiring high strength and fatigue resistance; 5. Special vehicles: armored vehicles, heavy-duty truck frames, balancing weight and structural strength; 6. Power tower structures: high-voltage transmission tower components in complex terrain.

What are the welding requirements for Q620C steel plates? +

Q620C welding key points to ensure joint performance: 1. Preheating temperature: 100~180℃ (thickness ≥30mm needs 150~180℃) to prevent cold cracking; 2. Interpass temperature ≤220℃ to avoid grain coarsening and toughness reduction; 3. Recommended welding materials: low-hydrogen electrodes/wires matching strength grade (E9018-G, ER90S-G); 4. Welding process: low heat input (≤25kJ/cm), multi-layer multi-pass welding to reduce residual stress; 5. Post-weld treatment: stress relief annealing (580~620℃) is recommended for thick plates or critical structures; 6. Welding inspection: mandatory non-destructive testing (UT/MT) for welds to ensure no internal defects.

What is the difference between Q620C and Q620D/Q620E grades? +

The core difference lies in low-temperature impact toughness requirements: 1. Q620C: 0℃ impact test (KV2≥34J), suitable for mild cold environments; 2. Q620D: -20℃ impact test (KV2≥34J), for cold regions like northern China; 3. Q620E: -40℃ impact test (KV2≥34J), for extremely cold areas. In addition, Q620D/E have stricter impurity control (P≤0.015%, S≤0.008%) than Q620C (P≤0.020%, S≤0.010%). All grades share the same strength index (yield ≥620MPa) but differ in toughness to adapt to different temperature working conditions.

What are the customization capabilities of Q620C steel plates? +

CEHE Steel provides comprehensive customization for Q620C steel plates: 1. Size customization: thickness 6~100mm, width 1500~4000mm, length 3000~18000mm (custom cutting available); 2. Performance customization: Z-direction performance (Z15/Z25/Z35) for thick plates, impact energy upgrade (KV2≥40J), surface quality grade (A/B/C/D); 3. Processing customization: flame/plasma cutting, beveling, shot blasting, anti-rust painting, edge rounding; 4. Certification customization: mill test certificate (MTC) per EN 10204 3.1/3.2, third-party inspection (SGS/BV/ABS) reports; 5. Delivery cycle: stock for standard sizes (3-5 working days), customized production (18-28 working days).

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