Q355B steel is a high-strength low-alloy (HSLA) structural steel widely utilized in the fields of shipbuilding and offshore engineering, owing to its exceptional weldability, toughness, and ability to maintain structural integrity even under harsh environmental conditions.
Compliant with the GB/T 1591-2018 standard, this steel grade characterized by a minimum yield strength of 355 MPa and outstanding toughness stands as an ideal choice for the fabrication of offshore piling, vessels, and various structural components.
What Is Q355B Steel?
Q355B is a Chinese low-alloy high-strength structural steel defined by the GB/T 1591-2018 standard. It is characterized by a minimum yield strength of 355 MPa and possesses excellent weldability. This steel grade is widely utilized in the fields of construction, bridge engineering, and heavy machinery.
Chemical Composition of Q355B steel
| Material | C | Si | Mn | P | S | Cr. | Ni | Cu | N |
| Q355B | ≤0.20% | ≤0.55% | ≤1.60% | ≤0.030% | ≤0.030% | ≤0.30% | ≤0.30% | ≤0.40% | ≤0.012% |
Mechanical Properties of Q355B steel
| Property | Typical Value/Range (Metric) |
|---|---|
| Yield Strength (0.2% offset) | 355 MPa (Min) |
| Tensile Strength | 470 - 630 MPa |
| Elongation | ≥ 20% |
| Impact Strength (Charpy) | ≥ 27 J |
| Impact Test Temp | +20°C |
Why Choose Q355B Steel for Ships & Marine Engineering Structures?
High Strength and High Toughness: Q355B is classified as a low-alloy, high-strength structural steel; with a yield strength of 355 MPa (for thicknesses ≤ 16 mm), it is capable of withstanding the complex stresses inherent in marine environments.
Excellent Weldability: Q355B exhibits excellent weldability, producing high-strength weld joints that are resistant to cracking during the welding process, thereby effectively reducing construction complexity and costs.
Broad Low-Temperature Toughness: As a Grade B steel, it guarantees sufficient impact toughness at lower temperatures (approximately 0°C or below), thereby meeting the environmental demands of marine settings-particularly those in cold regions.
Corrosion Resistance and Reliability: Compared to Q235B, Q355B offers superior performance stability; when combined with appropriate protective measures, it ensures a prolonged service life in corrosive environments, such as marine atmospheres and splash zones.
Applications of Q355B Steel in Ships & Marine Engineering Structures
Shipbuilding and Hull Structures: Used for the construction of ship hulls and deck machinery.
Offshore Engineering: Widely applied in offshore wind turbine foundations, mooring systems, and oil drilling platforms.
Port Infrastructure: Used as structural components for piers, quay walls, and mooring systems.
Marine Equipment and Containers: Used in the manufacturing of shipping containers, cargo boxes, and various types of specialized equipment.
Marine Structural Profiles: Available in a variety of forms, such as unequal-leg angle steel and various other structural profiles.
If you require further details regarding Q355B steel, please do not hesitate to contact us.
As a leading manufacturer of Q355B steel in China, GNEE boasts over 20 years of extensive industry experience. Our warehouses maintain a standing inventory of more than 50,000 tons year-round, ensuring that orders can be shipped in as little as seven days. In terms of quality assurance, we are a dual-certified supplier holding both API and ISO certifications, and we welcome inspections by third-party agencies such as SGS, BV, and Lloyd's.
By choosing our Q355B steel products, you will benefit from our comprehensive, customer-centric support services, as well as our extensive value-added processing capabilities. We would be delighted to provide full-spectrum support and assistance for your project.
Contact now to get Q355B steel
| Type | Q355B |
| Standard | AISI, ASTM, BS, GB, DIN, JIS, etc |
| Certificate | ISO,SGS,CE |
| Length |
Production according to customer requirements |
| Thickness | 8-160MM |
| Width | 2000-2500MM |
| Surface | Coated |
| Technique | Hot rolled |
| Package | Available on request or Standard Export Packing |
| Application | Widely used in Building Construction, Bridge, Architecture, Vehicles Components,hipping,High pressure container, Boiler, Large Structure steel etc. |
What does the name "Q355B" stand for?
"Q" stands for Yield Strength (Qu Fu in Chinese); "355" indicates the minimum yield strength of 355 MPa; and "B" represents the quality grade, specifically meaning the steel was impact tested at +20°C.
What are the international equivalents of Q355B?
Its most common international equivalents are European S355JR (EN 10025), American ASTM A572 Grade 50, and Japanese JIS SM490.
Can Q355B steel be easily welded?
Yes, Q355B has excellent weldability. Due to its low carbon equivalent (CEV), it can be welded using standard methods like SMAW, GMAW, and submerged arc welding without complex preheating.
Does Q355B require heat treatment?
Q355B is usually delivered in the Hot Rolled (HR) or Control Rolled (CR) condition. For very thick plates or special projects, it may be supplied as Normalized (N) or Thermomechanical Control Processed (TMCP).