Description
Direct Mill Supply, No Broker Markup — Hot rolled Q235B/Q345B/SS400 carbon steel plates produced on our own 3-line mill with full chemical and mechanical traceability from slab to shipment.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235B/Q345B Carbon Steel Plate |
| Product Type | Steel Plate |
| Steel Grade | Q235, Q235B, Q345, Q345B, SS400 |
| Standard | ASTM, GB |
| Thickness | 0.35–200mm |
| Length | 6m / 9m / 12m |
| Technique | Hot Rolled |
| Surface Treatment | Hot Rolled |
| Tolerance | ±1% |
| Processing Service | Bending, Welding, Decoiling, Punching, Cutting |
| Application | Water Retaining Wall |
| Invoicing | By Theoretical Weight |
| MOQ | 20 Ton |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Infrastructure & Civil Engineering | Water retaining walls, bridge bearing plates, foundation base plates |
| Industrial Construction | Factory column bases, warehouse mezzanine decking, platform grating supports |
| EPC Project Supply | Structural steel plates for cutting into fabricated beam-to-column connections |
| Structural Fabrication | Stiffener plates, gusset plates, splice plates for welded assemblies |
What Thickness Tolerance Stacks Up to on a Bolted Connection
±1% plate tolerance sounds tight until it meets a 0.35mm punched hole deviation.
When buyers outsource steel plate procurement to overseas mills, the real cost emerges at assembly — not at the mill gate. A 0.35mm thin plate ordered for perforated connection components can drift in both thickness and hole position once stacked with hot-rolled dimensional variation. Every GB standard hot rolled carbon steel plate supplier will quote you ±1% on paper, but the question is whether that tolerance is verified at the shearing line or only on the mill certificate. [NEED_CITE: hot rolled steel plate dimensional tolerance standards for structural fabrication]
Matching Plate Thickness to Structural Load Paths
For water retaining walls and foundation base plates, the 0.35–200mm range from this GB standard hot rolled carbon steel plate supplier covers everything from thin shear connectors to heavy load-distribution plates. Q345B plates in the 20–60mm range handle concentrated bearing loads at column bases, while Q235B in thinner gauges serves non-structural stiffeners and closure plates. Our in-house CNC punching and plasma cutting hold hole-position accuracy even on thin-gauge perforated work — the kind of control that prevents field rework when plates arrive at site with pre-drilled bolt patterns.
Engineering Compliance and Grade Selection Across Standards
Structural engineers specifying plates for EU, Middle East, or African infrastructure projects need grade equivalence confirmed before purchase. Q235B maps to S235JR under EN 10025; Q345B aligns with S355JR; SS400 sits between the two in yield classification. [NEED_CITE: steel grade equivalence mapping between GB, EN, and ASTM systems] For projects requiring ASTM compliance, our mill issues test certificates referencing both GB and ASTM chemical composition limits. Third-party inspection through SGS or BV verifies dimensional accuracy and surface quality before container loading — critical for customs clearance in markets with strict EN 1090 or AISC documentation requirements.
Hot Rolling, Grade Chemistry, and What They Mean for Your Fabrication
Hot rolled plates in Q235B and Q345B grades differ primarily in carbon and manganese content, which directly affects weldability and post-fabrication mechanical properties. Q235B’s lower carbon equivalent makes it easier to weld without preheating on thinner sections, while Q345B’s higher manganese provides strength for thicker structural members without sacrificing ductility. The hot rolling process produces a mill scale surface that must be removed by shot blasting before painting or galvanizing — our fabrication division handles this in-house, so plates arrive at your site ready for welding or coating. Invoicing by theoretical weight based on GB standard dimensions means you pay for the nominal cross-section, not the actual measured weight — a transparent calculation method that avoids disputes over scale tolerance.
The Hidden Cost of Unverified Plate Tolerance
Ordering the wrong grade or accepting plates outside tolerance doesn’t show up on the invoice — it shows up at site assembly. Plates that are undersized in thickness fail ultrasonic thickness testing during project handover. Plates with unverified chemistry crack during cold bending or produce porosity in welds. Material certificates without heat-number traceability get rejected by project inspectors, delaying customs clearance and triggering demurrage charges. [NEED_CITE: consequences of non-compliant steel plate documentation in international construction projects]
Why Source From a Vertically Integrated Mill and Fabricator
We produce the raw steel, roll the plates, and fabricate the finished components — all under one quality system and one point of accountability. Our mill operates 3 production lines covering 2,800+ specifications, so when your project calls for Q345B at 40mm and Q235B at 6mm in the same shipment, both come from the same material traceability chain. Every plate is tested in our in-house laboratory for chemical composition and mechanical properties, with mill test certificates issued per heat number. For international projects, we arrange SGS or BV third-party inspection before loading, and our logistics team handles oversized cargo packing and container optimization for mixed-thickness orders.
Documentation & Compliance
- Mill test certificate documenting Q235B/Q345B chemical composition and mechanical properties per GB/T 700 and GB/T 1591, with heat number traceability
- ASTM grade equivalence statement mapping Q235B to A36 and Q345B to A572 Grade 50 for projects requiring dual-standard compliance
- ISO 9001 quality management certificate covering the full production process from slab reheating to finished plate inspection
- SGS or BV third-party inspection report verifying dimensional accuracy, surface quality, and coating thickness per project specification
- Material traceability report linking each plate to its heat number, chemical analysis, and mechanical test results
- Export documentation including packing list, bill of lading, and certificate of origin for customs clearance in destination markets
Packaging, Loading & Delivery
- Hot rolled Q235B/Q345B plates bundled with steel strips and edge protectors to prevent corner damage during ocean transit
- Thin-gauge plates (0.35–6mm) packed on wooden pallets with interleaving paper to prevent surface scratching and moisture contact
- Mixed-thickness container loading optimized for 20ft and 40ft containers, with heavier plates (20–200mm) loaded at the bottom for weight distribution
- Custom cutting to 6m, 9m, or 12m lengths per order specification, with cut pieces labeled by heat number and grade for site identification
- Plate surfaces coated with anti-rust oil for sea freight protection, with oil type selected based on destination climate and storage conditions
- FOB, CIF, and DDP shipping terms available, with door-to-door logistics coordination for project sites in the Middle East, Southeast Asia, and Africa
Getting Your Quote and Mill Test Certificate
Send your project drawings in PDF or DWG format along with plate specifications — grade, thickness, length, quantity, and required standards — and we respond within 24 hours with a detailed quotation including material cost, processing charges, and shipping terms. Our engineering team reviews shop drawings before production begins, and we provide mill test certificates and third-party inspection reports as standard documentation with every shipment.
Frequently Asked Questions
Q: What is the difference between Q235B and Q345B for structural applications?
A: Q235B has lower carbon and manganese content, making it easier to weld and form for non-structural or lightly loaded components. Q345B offers higher yield strength for structural members requiring greater load-bearing capacity, such as column base plates and beam connections.
Q: Can you provide mill test certificates for international projects?
A: Yes, every plate is tested in our in-house laboratory and issued a mill test certificate documenting chemical composition and mechanical properties per heat number. We also arrange SGS or BV third-party inspection for projects requiring independent verification.
Q: Do you offer custom cutting and punching services?
A: Yes, our fabrication division provides CNC cutting, plasma cutting, punching, bending, and welding services. We work from your engineering drawings to produce finished components ready for site assembly.
Q: How is theoretical weight invoicing calculated?
A: Invoicing by theoretical weight uses the nominal dimensions (thickness × width × length) and standard steel density (7.85 g/cm³) to calculate weight, rather than actual measured weight. This provides transparent cost calculation based on GB standard dimensions.
Q: What is the minimum order quantity?
A: The minimum order quantity is 20 tons, which can be mixed across different grades and thicknesses to meet project requirements.
Get Your Quotation with Full Material Documentation
Send your project specifications — grade, thickness, dimensions, quantity, and destination port — to receive a detailed quotation and mill test certificate sample within 24 hours.
Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Website: www.xjystructure.com
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@xjystructure.com
Address: No.11889, Jingshi West Road, Lulian Group, Jinan City, Shandong Province, China
