P355Q steel is a hardenable and tempered weldable fine-grained steel for pressure vessels. It is a professional alloy steel with good plasticity, toughness, cold bending performance and welding performance. P355Q steel plates are often delivered in quenched and tempered condition.
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P355Q Chemical Composition |
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Grade |
The Element Max (%) |
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C |
Si |
Mn |
P |
S |
N |
B |
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P355Q |
0.16 |
0.4 |
1.5 |
0.025 |
0.015 |
0.015 |
0.005 |
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Mo |
Cu |
Nb |
Ni |
Ti |
V |
Zr |
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|
0.25 |
0.3 |
0.05 |
0.5 |
0.03 |
0.06 |
0.05 |
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Grade |
P355Q Mechanical Property |
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Thickness |
Yield |
Tensile |
Elongation |
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P355Q |
mm |
Min Mpa |
Mpa |
Min % |
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6-50 |
355 |
490-630 |
22% |
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|
50-100 |
335 |
490-630 |
22% |
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|
100-150 |
315 |
450-590 |
22% |
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Primary Applications and Industries
Pressure Vessel Fabrication: Used for constructing boilers, storage vessels, and tanks that handle high internal and external pressures, particularly where high tensile strength is needed (e.g., in accordance with EN 13445).
Petrochemical and Chemical Industry: Ideal for fabricating reactors, heat exchangers, and refinery equipment that requires high-pressure performance.
Energy Generation: Used in the production of steam turbines and critical piping systems.
Structural Applications: Due to its toughness, it is used in engineered, welded components where high yield strength is critical, including offshore structures.
Key Characteristics Affecting Applications
High Strength: Quenched and tempered (Q+T) process provides enhanced strength compared to standard normalized pressure vessel steels.
Low-Temperature Toughness: P355Q variants, particularly when specified with lower temperature grades, are suitable for cold environments.
Welding Performance: The fine-grained structure makes it highly weldable for complex, specialized pressure equipment.
Key advantages of P355Q steel include:
High Strength and Toughness: As a quenched and tempered (𝑄+𝑇) steel, it provides high tensile strength and excellent impact toughness, making it suitable for demanding pressure-containing equipment.
Good Weldability: Despite its high strength, it is specifically formulated to be weldable, enabling reliable fabrication of complex vessels.
Fine-Grained Structure: The fine-grain structure enhances toughness, particularly reducing the risk of brittle fracture in low-temperature environments.
Excellent Processing Performance: It features superior cold-bending and forming capabilities, which simplifies manufacturing processes.
Pressure Equipment Compliance: It is designed for pressurized systems, providing durability and safety, with improved hardness for high-load, high-pressure environments.
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What is P355Q?
P355Q is a low-alloy high-strength structural steel grade. It complies with European standards, featuring good toughness, weldability and mechanical properties. Widely used in construction, bridge and pressure vessel manufacturing that require reliable load-bearing capacity.
Which European standard does P355Q comply with?
P355Q complies with the EN 10028 standard, which specifies requirements for flat products made of weldable fine-grain structural steels. This standard defines its chemical composition, mechanical properties and inspection methods to ensure product quality.
What are the main chemical components of P355Q?
The main chemical components of P355Q include carbon (C), silicon (Si), manganese (Mn), phosphorus (P), sulfur (S), etc. P and S are controlled at low levels to avoid brittleness. Trace elements like niobium or vanadium may be added to enhance strength.
What is the minimum yield strength of P355Q?
The minimum yield strength of P355Q is 355 MPa, which is the key indicator for its high-strength performance. This ensures the steel can withstand large loads without permanent deformation, suitable for heavy-duty structural applications.
What is the tensile strength range of P355Q?
The tensile strength of P355Q ranges from 470 MPa to 630 MPa. This wide range provides flexibility in different engineering scenarios, balancing strength and ductility to meet various structural design requirements.
Is P355Q easy to weld?
Yes, P355Q has excellent weldability. Its low carbon equivalent and fine-grain structure reduce the risk of weld cracking. Common welding methods like arc welding, gas welding and resistance welding are all applicable without complex preheating.
What is the impact toughness of P355Q?
P355Q exhibits good impact toughness, especially at low temperatures. It can absorb energy and resist fracture under sudden impact loads, making it suitable for harsh working environments.
What are the common applications of P355Q?
P355Q is widely used in manufacturing bridges, buildings, pressure vessels, offshore structures and heavy machinery. Its high strength and toughness make it ideal for structures that need to bear heavy loads and resist external impacts.
Can P355Q be used in pressure vessel manufacturing?
Yes, P355Q is suitable for pressure vessel manufacturing. It meets the pressure-bearing requirements of related standards, with good fatigue resistance and corrosion resistance, ensuring the safety and stability of pressure vessels during operation.
What is the difference between P355Q and P355N?
The main difference lies in impact test temperature. P355Q requires impact testing at lower temperatures (-20℃) than P355N (-10℃), so it has better low-temperature toughness and is more suitable for cold environments.