Q550C High Strength Structural Steel Plate

Strictly Compliant with GB/T 16270-2009 | Quenched & Tempered State | Thickness Up to 150mm | Custom Sizes Available

Product Overview

Q550C 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).

Q550C is smelted by oxygen converter or electric furnace, with strict control of chemical composition and carbon equivalent (CEV ≤0.48%), ensuring excellent high strength and toughness. It is widely used in engineering machinery, construction structures, port machinery, bridge engineering and other fields that require high load-bearing capacity and structural stability.

According to GB/T 16270-2009 Appendix A, Q550C has approximate equivalent grades in European standards, and is the preferred material for high-strength structural components 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.

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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
Q550C	≤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.

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)
Q550C	550	530	490	640~820	590~770	16	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.

International Standard Approximate Comparison

According to GB/T 16270-2009 Appendix A (informative appendix) and official international standard data, the approximate equivalent grades of Q550C are as follows:

Property	Q550C (GB/T 16270-2009) China \| Quenched & Tempered	S550QL (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)	0℃ (KV2≥47J)	-40℃ (KV≥40J)	-40℃ (KV≥27J)
Max Carbon Content (%)	0.20	0.20	0.21
Carbon Equivalent CEV ≤	0.48~0.71 (by thickness)	0.49	0.50
Max Thickness (mm)	150	150	100
Main Applications	Engineering machinery, bridges	High-rise structures, cranes	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.

Application Cases

Engineering & Construction Machinery

Excavator arms, crane booms, loader buckets and hydraulic support components. Q550C's high strength-to-weight ratio meets the load requirements of machinery and reduces the overall weight.

Bridge & Building Structures

Large-span bridge deck plates, high-rise building structural beams and columns, steel structure workshops. Q550C's excellent toughness and stability adapt to complex outdoor environments.

Port & Heavy Machinery

Port cranes, container handlers, ship unloaders and hoisting equipment. Q550C's high load-bearing capacity and wear resistance meet the long-term heavy-duty operation requirements.

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.

What is the difference between Q550C, Q550D, Q550E and Q550F in GB/T 16270-2009? +

The core difference is the impact test temperature and index requirements: Q550C (0℃, KV2≥47J), Q550D (-20℃, KV2≥47J), Q550E (-40℃, KV2≥34J), Q550F (-60℃, KV2≥34J). The yield strength, tensile strength and elongation of the four grades are completely consistent, and the higher the letter grade, the better the low-temperature toughness.

What are the sampling and inspection rules of Q550C according to GB/T 16270-2009? +

According to the standard: 1. Chemical analysis: 1 sample per furnace, in accordance with GB/T 20066 sampling; 2. Tensile test: 1 sample per batch, transverse sample; 3. Impact test: 3 longitudinal samples per batch; 4. Ultrasonic inspection can be carried out sheet by sheet through negotiation. A batch is composed of steel plates with the same heat number, grade, heat treatment system and thickness difference ≤5mm, and the maximum weight of a single batch is 60t.

Can Q550C steel plate be welded and what are the requirements? +

Yes, Q550C has good weldability with CEV ≤0.48% (GB/T 16270-2009). For plates with thickness >25mm, preheating is recommended (preheating temperature 80-150℃) to prevent cold cracking. After welding, tempering treatment is recommended to eliminate welding stress. We can provide detailed welding process parameters and matching welding materials according to the actual application scenario.

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