Q390B Z-Direction Steel Plate (Equivalent to ASTM A572 Grade 60 / S395) Plate Supplier

Q390B Z15/Z25/Z35 Steel Plate – High-Strength Laminated Steel by Huaxiao Metal

Q390B is a low-alloy, high-strength structural steel (Yield Strength ≥390 MPa) designed for demanding environments where standard Q355B falls short. When enhanced with Z-direction testing (Z15, Z25, Z35), these plates provide exceptional resistance to lamellar tearing in heavy-section welding.

As a professional Q390B Z-steel supplier, Huaxiao Metal provides premium plates that meet GB/T 1591 and international equivalents like ASTM A572 Gr.60. Our plates are the preferred choice for heavy machinery frames, large-scale industrial workshops, and bridge structural nodes where through-thickness ductility is critical.

Every order comes with a full Mill Test Certificate (MTC) and optional third-party inspections (SGS/BV) to ensure global project compliance.

Available Dimensions & Supply Range

Material: Q390B high-strength low-alloy steel
Grades: Z15 | Z25 | Z35
Equivalent Grades: S395 / S420 (EN 10025), ASTM A572 Grade 60
Form: Hot-rolled steel plates
Thickness Range: 15mm – 200mm (customized upon request)
Width: 1500mm – 4000mm
Length: 3000mm – 12000mm
Standards: GB/T 1591-2008, EN 10025-6 equivalent

Huaxiao Metal Tip: Selecting the correct Z-grade for your steel plate is essential for preventing lamellar tearing in thick, welded components. Contact us to get expert advice on the most suitable grade for your project.

What Is Q390B Z15/Z25/Z35 Steel Plate?

Q390B steel plate is a high-strength low-alloy structural steel under GB/T 1591 standard, widely used in load-bearing structures.

The Z15, Z25, and Z35 classifications refer to through-thickness (Z-direction) properties, which indicate resistance to lamellar tearing during welding.

Z-Grade Comparison:

Grade	Reduction of Area (%)	Performance Level	Application
Z15	≥15%	Basic resistance	General structures
Z25	≥25%	Medium resistance	Bridges, machinery
Z35	≥35%	High resistance	Critical welded structures

Unsure if your Q390B structural components need Z-direction testing? Send us your drawing, and we will provide a professional recommendation.

Key Features

High Strength and Toughness

Q390B steel plates provide excellent tensile strength and impact resistance, ideal for heavy-duty engineering applications.

Lamellar Tearing Resistance

Z15, Z25, and Z35 grades ensure progressive levels of resistance against lamellar tearing during welding, making them perfect for thick plates and critical structures.

Excellent Weldability

Optimized chemical composition guarantees smooth welding without compromising mechanical properties.

Customizable Dimensions

Huaxiao Metal offers flexible thickness, width, and length options to meet your specific project requirements.

Global Export Capability

Our Q390B steel plates are packaged carefully for international shipping, ensuring the products arrive safely and in perfect condition.

Applications of Q390B Z-Direction Steel Plates

Heavy machinery and construction equipment
Bridges and structural steel frameworks
Pressure vessels and industrial fabrication
Offshore platforms and marine engineering
Oil & gas pipeline structures

Request a quote for Q390B Z15/Z25/Z35 steel plates today and secure competitive pricing with fast delivery from Huaxiao Metal.

Packaging & Export

Waterproof paper + steel strip packing
Wooden pallet / bulk shipment
Anti-rust protection
Customized packaging available

👉 Safe delivery guaranteed for long-distance shipping

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 Choose Huaxiao Metal?

15+ years of export experience
Stable stock for fast delivery
Competitive factory pricing
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).

We have supplied Z-direction steel plates to Europe, the Middle East, Southeast Asia, and South America

Work with a trusted steel supplier – send your inquiry today

FAQ – Q390B Z15 Z25 Z35 Steel Plate

Can Q390B be used in sub-zero temperatures?

Yes. While standard Q390B is tested at 20°C, we also provide Q390C, D, and E variants for impact testing at 0°C, -20°C, and -40°C respectively, all available with Z-direction performance.

Does Q390B Z-grade steel require special welding?

Due to its low sulfur and phosphorus content (high purity), it has excellent weldability. However, we recommend following standard high-strength steel preheating protocols based on plate thickness to ensure joint integrity.

When should I use Z35 instead of Z25?

If your project involves thick plates + heavy welding stress, Z35 is strongly recommended.

Can you provide UT tested plates?

Yes. We offer UT testing per ASTM A435, A578, or EN 10160 (Level S0, S1, S2) to ensure zero internal defects.

What is the MOQ?

We support both trial orders and large projects. For stock plates, the MOQ is 1 piece. For custom mill runs, it typically starts from 5-20 tons.

Can you cut plates to size?

Yes, we provide cutting, drilling, and machining services.

How does Q390B Z35 compare to European or American standards?

Q390B is a high-strength structural steel equivalent to S395/S420 (EN 10025) and ASTM A572 Grade 60. When ordered with Z35 performance, it meets or exceeds the through-thickness requirements of EN 10164 and ASTM A770. This makes it a cost-effective, high-performance alternative for international engineering projects that require a balance between weight reduction and structural safety.

What quality documentation do you provide for export orders?

Every shipment of our Z-direction steel plates includes a full Mill Test Certificate (MTC) compliant with EN 10204 3.1 (or 3.2 upon request). This report covers chemical analysis, mechanical properties (Yield/Tensile strength), impact testing, and specific Reduction of Area (RA%) values for Z-quality. We also support pre-shipment inspections by SGS, BV, or ABS to ensure 100% compliance with your project specifications.

Is Q390B Z-direction steel necessary for thick plate welding?

Yes. For welded joints where the plate thickness exceeds 40mm, internal stresses can lead to lamellar tearing. While standard plates only guarantee strength in the rolling direction, our Z25 and Z35 grades ensure ductility in the thickness direction (Z-axis). This is critical for T-joints, corner joints, and cruciform joints in heavy machinery and bridge nodes.