Q355B Z15 / Z25 / Z35 Steel Plate Supplier
Q355B Z Direction Steel Plate (Z15 / Z25 / Z35) – High Quality Structural Steel for Heavy Welding Applications
At Huaxiao Metal, we supply certified Q355B Z15, Z25, and Z35 steel plates with thickness ranging from 8mm to 200mm. Every batch comes with stable quality, Mill Test Certificates (MTC) compliant with GB/T 5313 standards, and export-ready packaging.
👉 If you are sourcing structural steel for critical welding structures, this grade is one of the most widely used choices exported from China for global heavy engineering projects.
Available Dimensions & Supply Range
Steel Grade: Q355B (High-Strength Structural Steel)
International Equivalents: S355JR / J2 (EN 10025); Grade 50 (ASTM A572)
Z-Direction Quality: Z15 / Z25 / Z35 (Tested per EN 10164 / ASTM A770)
Thickness: 8 mm – 200 mm (Support for heavy plate customization)
Width & Length: Up to 3,500 mm x 18,000 mm (Container-optimized sizes)
Delivery Condition: AR, N (Normalized), or TMCP
Quality Assurance: MTC 3.1/3.2, Ultrasonic Testing, SGS/BV Inspection
Our Q355B Z-direction steel is the ideal high-performance alternative to European EN 10025 S355 series and American ASTM A572 standards, offering identical mechanical properties and superior resistance to lamellar tearing.
What is Q355B Z-Direction Steel Plate?
Q355B is a Chinese structural steel grade defined under GB/T 1591, known for its 355 MPa minimum yield strength and excellent weldability.
However, for thick welded structures, standard plates are prone to lamellar tearing caused by welding shrinkage stress. Z-direction steel plates solve this issue by ensuring high mechanical properties in the thickness direction (Z-axis).
At Huaxiao Metal, we provide three levels of Z-quality testing based on GB/T 5313:
- Z15: ≥ 15% Reduction of Area (Basic Z-quality)
- Z25: ≥ 25% Reduction of Area (Medium level for industrial frames)
- Z35: ≥ 35% Reduction of Area (High-end for heavy offshore & bridge welding)
💡 Want to dive deeper into the technical mechanics? Read our full Z Direction Steel Plate Guide to learn how to prevent lamellar tearing.
Z15 vs Z25 vs Z35 Performance Levels
For Q355B projects, the following Z-direction levels are commonly requested based on structural load:
| Z Grade | Reduction of Area | Typical Application |
|---|---|---|
| Z15 | ≥15% | General welded structures |
| Z25 | ≥25% | Bridges and heavy structures |
| Z35 | ≥35% | Offshore platforms and critical welded joints |
Higher Z grades provide better resistance to lamellar tearing.
Deciding between Z15, Z25, or Z35 for your Q355B steel bridge project? Our technical team can help you choose the most cost-effective Z-quality level.
Mechanical Properties
| Grade | Yield Strength | Tensile Strength | Elongation | Z-Direction RA |
|---|---|---|---|---|
| Q355B Z15 | ≥355 MPa | 490 – 630 MPa | ≥20% | ≥15% |
| Q355B Z25 | ≥355 MPa | 490 – 630 MPa | ≥20% | ≥25% |
| Q355B Z35 | ≥355 MPa | 490 – 630 MPa | ≥20% | ≥35% |
Mechanical properties may vary slightly depending on thickness.
Standards & International Equivalents
EN 10025: S355JR / S355J2 + Z15/Z25/Z35
ASTM: A572 Grade 50
JIS: SS490 / SM490
Quality Assurance & Certification
- Full MTC (EN 10204 3.1 or 3.2): Comprehensive chemical analysis and mechanical testing.
- Z-Direction Testing Report: Specific RA% (Reduction of Area) data for Z15, Z25, or Z35.
- Third-Party Inspection: We regularly collaborate with SGS, BV, and ABS to provide pre-shipment inspections (PSI) as per client request.
- Heat Number Traceability: Ensuring 100% transparency from raw material to finished plate.
Key Advantages of Q355B Z Direction Steel Plate
Excellent Lamellar Tearing Resistance
Through-thickness properties significantly reduce the risk of lamellar tearing in thick welded joints.
High Structural Reliability
Stable mechanical performance ensures safety in large welded structures.
Good Weldability
Optimized chemical composition improves welding performance.
Custom Fabrication Support
Cutting, beveling, and surface treatment services available.
Typical Applications
Q355B Z Direction Steel Plates are widely used in:
Bridge girders and large steel bridges
Offshore platform structures
High-rise building steel frames
Wind power tower foundations
Heavy machinery bases
These applications often involve thick plates and complex welding, where Z-direction performance is essential.
For engineers, see our Z Direction Steel Plate Guide to understand why Z-direction properties matter.
Custom Processing Services
We provide additional processing services for project orders:
CNC Flame Cutting
Plasma Cutting
Edge Beveling
Surface Blasting & Priming
These services reduce fabrication time for customers.
Why Source Q355B Z-Direction Steel from Huaxiao Metal?
MTC Documentation: Every batch comes with a Mill Test Certificate according to EN 10204 3.1.
Third-Party Inspection: Supports SGS, BV, and Lloyd’s Register testing.
Processing Services: Precise CNC flame cutting, plasma cutting, and pre-treatment (blasting & painting).
FAQ – Q355B Z-Direction Steel
What is the main difference between Q355B and Q355B-Z25?
While both have the same yield strength, the Z25 version undergoes specialized testing to ensure it won’t tear through its thickness during heavy welding.
Can Q355B Z-direction plates be customized?
Yes. We provide:
Custom thickness, width, and length
Cutting, edge beveling, and surface treatment
Project-based supply for large orders
Submit your project details to receive a tailored quotation.
How is the quality of Q355B Z-direction steel ensured?
Each plate undergoes:
Through-thickness tensile testing
Ultrasonic testing (UT)
Mill Test Certificates EN10204 3.1
Optional third-party inspection (SGS, BV, TUV)
This guarantees that the plate meets the specified Z-direction performance.
What standards do Q355B Z-direction steel plates comply with?
Our Q355B Z-direction plates meet:
GB standard (China)
EN 10164 equivalent (Europe)
Can also supply ASTM equivalents upon request
Can Q355B Z steel be used in bridges?
Yes. For heavy bridge engineering, Z25 and Z35 are the industry benchmarks for critical structural nodes. We recommend Q355B Z25 for standard spans to balance cost and performance, while Z35 is reserved for complex, thick-welded joints. We provide full Mill Test Certificates (MTC) with every shipment to ensure your project complies with local infrastructure regulations.
Is Q355B Z35 suitable for offshore structures?
Yes, absolutely. Q355B Z35 is a standard choice for offshore platforms, subsea equipment, and wind turbine foundations. At Huaxiao Metal, we ensure our Z35 plates undergo rigorous ultrasonic testing (UT) to meet international offshore safety standards. The Z35 rating guarantees a reduction of area (RA) of ≥35%, which is critical for resisting lamellar tearing in high-salinity and high-stress marine environments.
How do I request a quote quickly?
Provide:
Steel grade and Z level (Z15/Z25/Z35)
Plate thickness and size
Quantity
Project type/application
Delivery port
Our technical team will provide material recommendations, competitive pricing, and fast delivery.
📩 Click here to submit your RFQ now and get a response within 24 hours.
Request a Quote for Q355B Z15 Z25 Z35 Direction Steel Plate
As a professional Z-Direction Steel Plate supplier, Huaxiao Metal offers a wide range of thicknesses and sizes for Q355B Z-grade plates. Whether you need standard stock or custom-cut components, we are ready to support your project.
Contact us today for the latest price and lead times.
