GB/T700 & GB/T1591 Carbon Steel Plate Price 2025

GB/T700 (general carbon structural steels) and GB/T1591 (low-alloy high-strength structural steels) serve different parts of the market: GB/T700 grades such as Q235 remain the cost-efficient choice for routine structural work, while GB/T1591 grades (Q345, Q390, Q420, etc.) demand a price premium because of alloying, tighter mechanical control and wider application in heavier structures and demanding environments. In 2025 suppliers quote very wide regional price bands — roughly several hundred to a few thousand USD per tonne depending on grade, processing, and contract terms — so prudent buyers should combine technical selection with market-timed procurement and clear inspection clauses.

what we cover and why it matters

We write as materials specialists at luokaiwei to deliver a practical, authoritative reference on GB/T700 and GB/T1591 carbon steel plates, with emphasis on their 2025 market positioning and price ranges. The article explains standards, chemistry and mechanical behavior, real-world applications, purchasing checklists, and a global price snapshot for 2025 — all framed so procurement, design, and QA teams can act without hunting fragmented sources. Key technical points and market drivers are summarized and footnoted to primary marketplace and standards resources.

Short primer on the two standards

• GB/T700 — Carbon structural steels: This is China’s foundational standard for ordinary carbon structural steels. It lists grades such as Q195, Q215, Q235, Q255 and Q275 and prescribes dimensions, delivery conditions, testing, and marking for hot-rolled plates, strips, sections and bars used in general structural applications.

• GB/T1591 — Low-alloy, high-strength structural steels: Introduced for higher-performance structural work, GB/T1591 covers micro-alloyed steels (Q345 and above, including Q345B/Q345C, Q420, Q460 series) that contain controlled additions (Mn, Si and microalloying elements such as Nb, V, Ti). These elements and modern thermomechanical rolling improve yield strength, toughness and weldability at thicknesses used in bridges, heavy equipment and offshore structures.

Chemistry and microalloying — what changes between the two

We emphasize composition because it explains price and performance differences:

• GB/T700 grades are essentially carbon-manganese steels with narrow compositional control for general structural use. Typical elements: C (limited), Si, Mn, P and S (low). These steels are optimized for formability and welding convenience at low cost.

• GB/T1591 grades intentionally raise Mn and Si ranges and add trace microalloying elements (vanadium, niobium, titanium) in controlled amounts. Those microalloy elements refine grain size and enable higher yield strength without heavy increases in carbon. For medium-to-thick plates, the TMCP (thermomechanical control processing) route further enhances strength–toughness balance. The presence of microalloying and controlled processing increases manufacturing complexity and cost.

Practical effect: for similar thickness, a Q345 (GB/T1591) plate will typically be stronger and frequently cost more than a Q235 (GB/T700) plate because of alloy cost and process controls.

Mechanical property differences and cross-references

Mechanical properties vary by grade and thickness. Typical contrasts we use in design discussions:

• Yield strength: GB/T700 (Q235 family) yield ~235 MPa nominal; GB/T1591 (Q345 family) yield ~345 MPa or higher depending on grade (Q390, Q420, Q460).

• Tensile strength and elongation: GB/T1591 grades have higher tensile strength brackets and are specified with notch-toughness requirements in many subgrades to guarantee performance at lower temperatures.

Designers often check equivalence tables when substituting materials across regions. For example, Q345 (common GB/T1591 grade) is broadly compared with ASTM A572 Gr.50 for approximate mechanical similarity — but composition and delivery criteria differ and must be reconciled for critical structures. Always verify the exact sub-grade, delivery state and impact testing requirement prior to substitution.

Manufacturing methods, delivery state and QA

• Hot rolling vs TMCP: GB/T700 product lines are commonly produced by conventional hot rolling. GB/T1591 often employs TMCP or controlled rolling to produce finer microstructures enabling higher strengths without heavy heat treatment.

• Delivery condition and testing: Standards specify sampling, tensile tests, impact (where required), bending tests, and chemical analysis. Mill certificates (3.1/3.2 equivalent) and third-party inspection are standard options for export and large projects. The purchaser should specify required reports and acceptance criteria in the PO.

• Surface and flatness control: Plate finish, mill edge condition, and flatness tolerances differ between mills and cost tiers. Inclusion of grinding, shot-blasting, heavy plate levelling or stress-relieving adds to lead time and price.

Applications — when to specify GB/T700 vs GB/T1591

We recommend this practical rule-of-thumb:

• Choose GB/T700 (Q235 and similar) when the structure is conventional, loads moderate, welding and forming are priorities and cost is critical (e.g., small building frames, light machinery).

• Choose GB/T1591 (Q345 and above) for heavier civil structures, cranes, bridges, ship hull structures, pressure-bearing subframes, and any application that needs extra yield strength, better toughness or improved fatigue resistance. The microalloying and rolling route gives better performance for similar thickness, which can enable lighter designs.

How standards affect procurement and specification language

We typically instruct procurement teams to:

1. State the exact standard and grade (for example: “Plate — GB/T1591 Q345B, thickness X mm, delivery condition AR, impact test —40°C as per clause Y”).

2. Include inspection and certification requirements (mill test certificate, third-party inspection, test intervals, sampling plan).

3. Specify surface and edge finish, straightness, packing and lifting markings, plus acceptance criteria for rejects and rework.

Clear POs reduce ambiguity and disputes that otherwise surface at shipment or fabrication.

Price landscape in 2025 — how to read quotes

High-level observation: 2025 remains a volatile year for steel. Published indices and supplier listings show wide ranges because of product type (plate vs coil), grade, processing, the lot size and local taxes or trade measures. Buyers should treat published “per tonne” numbers as indicative, not prescriptive.

Key market data points we reference

• Broad market summaries show construction-grade carbon steel commonly trading in ranges that can span roughly $330–$1,500 per metric tonne depending on product form and region. Lower-end figures reflect bulk basic crudely processed material; higher figures reflect value-added, short supply or small-lot orders.

• Examples from supplier listings in China often show hot-rolled structural plates (basic grades) around USD 660–690/ton for some grades in standard thicknesses — remember, supplier listing prices frequently exclude processing, cutting, inspection, and shipping.

• Industry commentary for 2025 shows regional indices bouncing month to month: cold-rolled coil and hot-rolled coil values have been reported in the low-to-mid thousands USD/ton in some markets while fabricated plate indices vary with demand. Price indices and spot markets should be used together to form a negotiated contract price.

Global price comparison table — indicative 2025 ranges

Note: These are representative landed/FOB ranges typical in 2025 for hot-rolled structural carbon plates (basic, common thicknesses, mid-volume orders). Exact quotes depend on thickness, grade, delivery tests, size and logistics. We encourage buyers to request firm mill offers.

How to read the table: the lower end typically represents plain Q235-class plate with minimal testing or standard mill pack; the upper end represents heavy plate, higher grades (Q420+), certified impact testing, and small-quantity or urgent orders. Use this table as a negotiation baseline, not a guaranteed price.

What drives the price differences between GB/T700 and GB/T1591 plates?

We track five principal drivers:

1. Raw material (iron/scrap) and alloy cost: Microalloy elements and higher Mn/Si content add to input cost. Scrap pricing fluctuations feed quickly into mill offers.

2. Processing route: TMCP and controlled rolling plus extra QA increase mill cost vs conventional hot rolling.

3. Testing and certifications: Impact testing, traceability paperwork and third-party inspection increase transaction cost and may be required by project owners for GB/T1591 grades

4. Logistics and regional trade policies: Freight, energy and any duties or quotas create regional price spreads.

5. Demand for specific end-uses: Large infrastructure or defense projects can absorb premium plate volumes and cause temporary spikes in price.

Buying tactics we recommend

• Specify fully up front. Give grade, plate thickness, impact test temperature (if needed), acceptance criteria and certificate type. This avoids “extras-for-extras” pricing.

• Request two-tier offers: (A) Basic mill certificate only, (B) Full third-party inspection and impact testing. Compare total landed costs.

• Tie inspection acceptance criteria to rework allowances. Include clear rejection thresholds to avoid disputes on arrival.

• Batch purchases and timing: larger lots reduce per-tonne premiums; coordinate delivery windows to align with mill production schedules to avoid rush premiums.

• Consider design tradeoffs: in some cases specifying higher yield GB/T1591 allows thinner plates and lower total mass despite higher per-ton cost.

Quality assurance checklist (for purchase orders)

We include the checklist we use internally:

• Purchase order: standard & grade (GB/T700 or GB/T1591), grade sub-type (e.g., Q345B), thickness and tolerances.

• Mechanical properties: yield, tensile, elongation and specified impact energy at stated temperature.

• Chemical analysis: acceptable ranges and certificate type.

• Test reports: mill certificate (3.1/EN10204 or equivalent), non-destructive tests if required.

• Surface & flatness requirements, packing and lifting markings.

• Inspection: option for buyer’s or third-party inspection at mill.

• Warranty and replacement terms for rejected shipments.

Typical specification examples (PO snippets we use)

We provide sample lines you can adapt:

• “Supply and deliver hot-rolled plate to GB/T1591-2018 Q345B, thickness 10 mm ±0.3 mm, delivery state AR, impact test −20°C, mill test certificate 3.1, third-party inspection by [name].”

• “Supply hot-rolled plate to GB/T700-2006 Q235A, thickness 6 mm ±0.2 mm, standard mill certificate, surface finish pickled and oiled, packed for export.”

Common equivalence and substitution notes

We caution that equivalence charts are a starting point but are not guaranteed replacements:

• Q345 ↔ ASTM A572 Gr.50 is often cited as similar in strength, but compositional differences and different testing/delivery states mean engineers must verify toughness and welding requirements before substitution.

• For structural design across code jurisdictions, follow the code (e.g., Eurocode, ASTM or Chinese codes) that governs the project and confirm material acceptance with the structural engineer.

Risk factors and mitigation

We list common procurement risks and methods to mitigate them:

• Hidden chemistry deviations: require full chemical certificate and, if critical, independent verification.

• Short-shipment or incorrect thickness: specify acceptance sampling and measurement procedure on the PO.

• Late delivery and fabrication hold-ups: include penalties or flexible delivery windows in contracts.

• Price volatility: use month-tied contracts or put-call options where volumes justify hedging.

Frequently asked questions (FAQs)

Q1 — How much more expensive is a GB/T1591 Q345 plate vs GB/T700 Q235?
A: There is no single answer — for 2025 we typically see a premium for Q345 over Q235 that ranges from a low single-digit percent up to 30%+ depending on test requirements, thickness and lot size. Microalloy additions and required impact testing tend to be the main contributors to the premium. Always request comparative firm quotes for the exact thickness/volume.

Q2 — Can I substitute Q345 for Q235 to save weight?
A: Yes, often a higher-yield material permits thinner plate sections, which can reduce mass and possibly overall cost — however you must confirm fabrication, welding procedure qualifications, buckling design and connection details with the structural engineer before substituting.

Q3 — Which tests are essential to ask for on the mill certificate?
A: Minimums we require: full chemical analysis, tensile test, elongation, and specified impact tests (when project calls for low-temperature toughness). If material will be welded in critical locations, include Charpy-V testing and specify test temperature.

Q4 — How often should I inspect at the mill?
A: For routine small orders you might accept mill QC with documentation. For large projects or critical components we advise third-party inspection at the mill, including sampling beyond mill minimums and witness of destructive tests.

Q5 — How should I interpret price indices vs supplier quotes?
A: Indices give macro direction but rarely reflect a particular mill’s finished plate price for a specific grade, thickness and test level. Use indices for trend context and supplier quotes for transactional negotiation. If needed, add freight, duties, testing and cutting costs to index figures to derive a realistic landed price.