Description
Full-Range HD Plate Supply — Covering Q205HD through Q420HD in 8–120 mm thickness with original mill test certificates for every heat number.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | High Strength Steel Plate Q205HD–Q420HD |
| Product Type | Steel Plate |
| Steel Grade | Q205HD, Q230HD, Q250HD, Q275HD, Q345HD, Q420HD |
| Standard | Chinese GB Standard for High Strength Construction Steel; ASTM |
| Section Shape | Flat plate |
| Thickness Range | 8 mm – 120 mm |
| Tolerance | ±1% |
| Yield Strength | 205 MPa – 420 MPa (graded by HD mark) |
| Tensile Strength | 410 MPa – 705 MPa |
| Elongation Rate | ≥18% |
| Low Temperature Impact | -30℃ |
| Carbon Content | 0.12% – 0.20% |
| Manganese Content | 1.20% – 1.60% |
| Sulfur Content | <0.015% |
| Phosphorus Content | <0.020% |
| Surface Treatment | Hot Rolled |
| Processing Service | Plasma cutting, flame cutting, hole drilling, bending, welding, punching |
| Invoicing | By theoretical weight |
| Delivery Time | 22 – 30 days |
| MOQ | Flexible (trial orders to bulk orders) |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Heavy Machinery Manufacturing | Structural frames for cranes, excavators, and mining equipment |
| Large-Scale Construction | Load-bearing columns, base plates, and transfer girders in high-rise buildings |
| Infrastructure & Civil Engineering | Bridge bearing pads, retaining wall reinforcements, and port crane girders |
| Industrial Fabrication | Pressure vessel supports, conveyor system frames, and silo structural shells |
Where Trace Element Control Separates Weldable Plate from Scrap
Sulfur below 0.015% and phosphorus below 0.020% keep hydrogen-induced cracking out of thick-plate weld joints.
When import buyers receive high strength steel plate with elevated sulfur, the first sign of trouble appears weeks later — not at the mill gate, but in the welder’s puddle. Hot cracking along the fusion line, lamellar tearing in T-joints on 40 mm Q345HD sections, and impact values that collapse below the -30℃ threshold the project spec demands. The root cause is always the same: uncontrolled residual elements that the mill certificate conveniently rounded off. [NEED_CITE: influence of sulfur and phosphorus on weldability of high strength structural steel]
Matching HD-Grade Yield to Structural Load Paths
Every HD designation in the Q205HD to Q420HD range maps to a distinct load-bearing tier. Q205HD and Q230HD serve secondary frames and non-critical bracing where ductility matters more than raw strength. Q345HD — the workhorse grade across African and Southeast Asian infrastructure — handles primary beam-to-column connections in multi-story structures. Q420HD steps into heavy crane girders and mining equipment booms where every kilogram of dead weight counts. The controlled manganese range of 1.20%–1.60% ensures that even at 120 mm thickness, the plate through-hardens uniformly without brittle martensite bands at the core.
Engineering Compliance Across Export Markets
High strength steel plate shipped into the EU must carry CE documentation demonstrating conformity with harmonized standards; projects in North America reference ASTM equivalence for grade substitution approvals. [NEED_CITE: steel grade equivalence between Chinese GB and international EN/ASTM standards] The ±1% thickness tolerance on our HD series keeps theoretical-weight invoicing aligned with actual structural calculations — a detail that matters when a 40 mm Q420HD plate arrives at 37 mm and the engineer’s load table no longer applies. Ultrasonic inspection per Chinese GB standards catches internal laminations before they become field failures on load-bearing weldments.
Carbon-Manganese Balance and Its Effect on Field Welding
The 0.12%–0.20% carbon window in the HD series sits deliberately below the 0.25% threshold where preheating becomes mandatory for thicknesses above 25 mm. Combined with manganese at 1.20%–1.60%, this gives the plate a carbon equivalent low enough for standard SMAW and FCAW procedures without preheat on joints up to 40 mm — a practical advantage on remote construction sites where induction heaters are unavailable. Hot-rolled surface condition accepts shop primers directly after standard abrasive blast cleaning, eliminating the extra pass required to remove mill scale from normalized plates.
The Hidden Price of Unverified Mill Certificates
A mill certificate that lists Q345HD but delivers material with 290 MPa yield instead of 345 MPa does not show its cost at the port — it shows it when the structural inspector rejects the welded connection, when the crane girder deflects beyond tolerance under proof load, or when customs holds the container because the certificate steel grade does not match the purchase order. [NEED_CITE: consequences of material non-conformance in structural steel procurement] Re-cutting, re-welding, and re-certifying a rejected batch on-site costs multiples of the original plate price — and the project timeline absorbs every day of delay.
Why Import Buyers Source HD Plate From Jinan
Our three production lines run Q205HD through Q420HD simultaneously, meaning a single container can mix 20 mm Q230HD bracing plates with 60 mm Q420HD crane girders — consolidated under one set of mill certificates and one customs declaration. Every heat undergoes spectrochemical analysis in our in-house lab before rolling, and the resulting certificate travels with the plate to your destination port. Third-party inspection through SGS or BV is available at any production stage. For long-term partners, volume discount tiers activate automatically after the third shipment, and our export team handles container loading optimization to keep freight cost per ton down on heavy-gauge orders.
Documentation & Compliance
- Mill test certificate documenting Q205HD–Q420HD chemical composition (C, Mn, S, P) and mechanical properties (yield, tensile, elongation, -30℃ impact) per heat number
- CE certification files supporting customs clearance for European Union destination ports
- ISO 9001:2015 quality management certificate covering the full plate rolling and inspection process
- SGS or BV third-party inspection report available upon request at production or pre-shipment stage
- Material traceability by heat number linking each plate to its original slab, rolling schedule, and test results
- Full customs document package including packing list, bill of lading, and certificate of origin
Packaging, Loading & Delivery
- Hot-rolled HD plates bundled with galvanized steel strips at 1.5 m intervals, edges protected by angle steel to prevent transport damage to plate surfaces
- Surface coated with anti-rust oil after rolling to preserve hot-rolled finish during ocean transit up to 45 days
- Container loading plans optimized for 8–120 mm thickness combinations, maximizing payload per 20ft and 40ft open-top or flat-rack units
- Plates marked with heat number, steel grade (e.g., Q345HD), thickness, and length in weatherproof stencil paint on both ends
- FOB, CIF, and DDP terms available with door-to-door logistics coordination for project sites inland from major ports
Request a Grade-Specific Quote With Mill Test Preview
Submit your thickness, steel grade, quantity, and destination port — we return a detailed quotation with sample mill test certificate format, processing options, and estimated production lead time within 12 hours.
Get Your High Strength Steel Plate Quote Today
Send your specifications to admin@sdxinjiyuan.com or reach us on WhatsApp at +86 188 5315 7756 for immediate pricing and documentation review.
