P355Q is a premium low-alloy high-strength structural steel grade that adheres strictly to European industrial standards. It is renowned for its excellent comprehensive performance, including superior toughness, outstanding weldability, and stable mechanical properties even in complex working conditions. This steel grade is widely applied in key fields such as large-scale construction projects, bridge engineering, and pressure vessel manufacturing, particularly in scenarios that demand reliable load-bearing capacity, long-term durability, and resistance to external environmental impacts.
Chemical Composition( %):
|
Grade/ Material |
Element |
Composition( Max-A, Min-I) |
|
DIN EN 10028-6 P355Q |
C |
A:0.16 |
|
Mn |
A:1.50 |
|
|
Si |
A:0.40 |
|
|
P |
A:0.025 |
|
|
S |
A:0.015 |
Mechanical Properties( Mpa)
|
Grade/ Material |
Tensile Test |
MPa |
|
DIN EN 10028-6 P355Q |
Tensile Strength |
490-630 |
|
Yield Strength |
I:355 |
|
|
Elongation |
I:22% |
|
|
Impact Test( if any) |
-20℃ |
advantages
High Strength and Toughness Balance: P355Q provides a good combination of yield strength and impact toughness, making it suitable for pressure vessels and boilers operating under demanding conditions.
Excellent Weldability: With proper preheating and post-weld heat treatment, P355Q can be readily welded using common processes such as SMAW, GMAW, and SAW, ensuring reliable joint quality.
Good Low-Temperature Performance: It maintains high toughness at low temperatures, meeting the requirements for equipment used in cold climates or cryogenic applications.
Stable Microstructure: The quenched and tempered (Q&T) process results in a fine-grained, uniform microstructure, which enhances fatigue resistance and structural stability.
Corrosion Resistance: While not a stainless steel, P355Q offers reasonable resistance to atmospheric and mild corrosive environments, especially when properly coated or protected.
Cost-Effective: Compared with higher-alloyed steels, P355Q provides excellent performance at a competitive cost, making it a preferred choice for many pressure vessel applications.
P355Q Process Characteristics
Precise Refining Control: Adopts LF furnace refining and VD vacuum degassing, effectively removing impurities and gas, ensuring chemical composition uniformity and material cleanliness.
Controlled Rolling & Heat Treatment: Combines controlled hot rolling with quenching-tempering (Q&T) process, optimizing grain structure to balance high strength and excellent toughness.
Strict Temperature Regulation: Austenitizing (880–950°C) and tempering (580–680°C) temperatures are precisely controlled to guarantee stable microstructure and mechanical properties.
Rigorous Defect Detection: Integrates multi-stage non-destructive testing (ultrasonic, visual) and mechanical testing, eliminating defective products and ensuring process reliability.
Weld Process Compatibility: Matches standardized preheating and post-weld heat treatment, reducing residual stress and preventing cracks, ensuring welding process stability.
P355Q Applications
Pressure Vessels & Boilers: As a key material compliant with EN 10028-6, it is widely used to manufacture medium-to-high pressure vessels, boiler drums, heat exchangers and storage tanks for petroleum, natural gas and chemical media, due to its excellent pressure-bearing capacity.
Petrochemical Industry: Applied in refining equipment like hydrocracking reactors, fractionating towers and high-pressure pipelines, adapting to harsh working conditions involving high temperature, pressure and sulfur-containing media.
Power Generation: Utilized in thermal power plants for steam pipelines, boiler components and auxiliary pressure-bearing equipment, ensuring stable operation under long-term high-temperature steam conditions.
Marine & Offshore Engineering: Used in offshore oil platforms, marine pressure vessels and ship-borne boiler systems, resisting seawater corrosion and complex sea load impacts.
Heavy Machinery & Construction: Applied in large engineering machinery (cranes, excavators) and high-pressure structural components (urban heating pipelines), providing reliable structural support with balanced strength and ductility.
Full specification and details are available on request. The above information is provided for guidance purposes only. For specific design requirements please contact our technical sales staff.
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.
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 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.
What is the density of P355Q?
The density of P355Q is approximately 7.85 g/cm³, the same as ordinary carbon steel. This density value is widely used in engineering calculations to estimate the weight of structures and components made of P355Q.
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 is the machinability of P355Q?
P355Q has good machinability. Its uniform structure and moderate hardness allow for easy cutting, drilling and milling with common machine tools. Proper cutting tools and parameters can ensure high machining efficiency and surface quality.
What is the maximum thickness of P355Q plates?
The maximum thickness of P355Q plates can reach 200mm or more, depending on manufacturing standards and customer requirements. Thicker plates may need special heat treatment to ensure consistent mechanical properties throughout the thickness.
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.
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.