What is Q345NS sulfuric acid dew point corrosion resistant steel plates?
Q345NS is a low-alloy high-strength structural steel, specifically developed as a sulfuric acid dew point corrosion-resistant steel. It complies with the standard GB/T 28907-2012. The material offers a minimum yield strength of ≥ 345 MPa and a tensile strength of 470–630 MPa, combining high strength with good impact toughness.
Through the controlled addition of micro-alloying elements such as antimony (Sb), copper (Cu), and chromium (Cr), with typical contents of approximately Sb 0.02–0.10%, Cu 0.20–0.50%, and Cr 0.30–0.80%, the steel demonstrates significantly improved corrosion resistance in a 70°C, 50% dilute sulfuric acid environment. Its corrosion rate is lower than that of ordinary carbon steel, typically only about one-third to one-half, showing excellent pitting resistance and passivation behavior.
With these core technical advantages, Q345NS is mainly used in power plant chimneys, including internal liners, structural components, and flue gas channels. In low-temperature environments where high-sulfur flue gas is prone to condensation, it can extend the service life of chimney structures by approximately 2–3 times, effectively resisting strong acidic condensate corrosion.
At the same time, compared with conventional carbon steel solutions, it can reduce life-cycle maintenance and replacement costs by about 30%–50%, improving operational economy and reliability.
We supply Q345NS sulfuric acid dew point corrosion-resistant steel, designed for low-temperature flue gas environments. With a smooth surface finish, it reduces the adhesion of acidic dust and deposits, lowering cleaning and maintenance frequency by about 20%–40%.
Compared with carbon steels such as Q235B and Q345B/C/D, which are prone to severe acid corrosion and thinning under high-sulfur conditions, Q345NS maintains high strength (yield strength ≥ 345 MPa, tensile strength 470–630 MPa) and forms a stable protective film through micro-alloying with elements such as Sb and Cu.
In power plant chimney applications, its service life is about 2–3 times longer than Q345B steel, while reducing downtime and maintenance-related losses by approximately 30%–50%.
Q345NS Steel Plate Specification
| Item | Specification |
|---|---|
| Product Name | Q345NS Sulfuric Acid Dew Point Corrosion-Resistant Steel Plate |
| Material Grade | Q345NS / Low-Alloy High-Strength Steel |
| Standard | GB/T 713 / GB/T 1591 (for reference application standards depending on use) |
| Product Form | Hot Rolled Steel Plate / Structural Steel Plate |
| Thickness Range | 6 mm – 120 mm |
| Width Range | 1000 mm – 2500 mm |
| Length Range | 2000 mm – 12000 mm (or customized cutting) |
| Surface Condition | Hot rolled / Shot blasted / Pickled (optional) |
| Manufacturing Process | Melting → Continuous Casting → Controlled Rolling (TMCP) → Controlled Cooling → Straightening |
| Delivery Condition | As rolled / Normalized / Controlled rolled condition |
| Yield Strength | ≥ 345 MPa |
| Tensile Strength | 470 – 630 MPa |
| Elongation | ≥ 21% |
| Corrosion Performance | Excellent resistance to sulfuric acid dew point corrosion |
| Certification | ISO 9001 / SGS / BV / EN 10204 3.1 or 3.2 |
| Inspection | Chemical composition analysis, tensile test, impact test, UT testing, dimensional inspection |
| Packaging | Waterproof paper, plastic film, steel straps, wooden pallets, seaworthy export packing |
Q345NS Steel Plate Physical Properties
| Property | Value |
|---|---|
| Density | ~7.85 g/cm³ |
| Yield Strength | ≥ 345 MPa |
| Tensile Strength | 470 – 630 MPa |
| Elongation | ≥ 21% |
| Elastic Modulus | ~200 GPa |
| Poisson's Ratio | ~0.30 |
| Impact Toughness | ≥ 34 J (at room temperature, typical requirement depending on standard) |
| Hardness | ~140 – 180 HB (typical range) |
| Thermal Conductivity | ~45 – 55 W/m·K |
| Thermal Expansion Coefficient | ~11 – 13 ×10⁻⁶ /K |
| Service Temperature | Suitable for low to medium temperature flue gas environments |
| Corrosion Performance | Excellent resistance to sulfuric acid dew point corrosion |
Q345NS Steel Plate Chemical Composition
| Element | Content (%) |
|---|---|
| Carbon (C) | ≤ 0.12 |
| Silicon (Si) | 0.20 – 0.50 |
| Manganese (Mn) | 0.80 – 1.50 |
| Phosphorus (P) | ≤ 0.025 |
| Sulfur (S) | ≤ 0.015 |
| Chromium (Cr) | 0.30 – 0.80 |
| Nickel (Ni) | ≤ 0.30 |
| Copper (Cu) | 0.20 – 0.50 |
| Iron (Fe) | Balance (Remaining) |
Heat Treatment of Q345NS Steel Plate
Q345NS steel is produced by a thermo-mechanical controlled rolling (TMCP) process with controlled cooling, without quenching or traditional hardening.
This process refines the microstructure into a uniform fine-grained structure (typically ASTM No. 8–12), providing a good balance of strength, toughness, and resistance to sulfuric acid dew point corrosion.
Compared with conventional hot-rolled steels, TMCP improves property uniformity by about 20%–30% and enhances low-temperature impact toughness by 15%–25%. Q345NS achieves its performance through alloy design and controlled rolling, reducing corrosion rates in acidic condensation environments by up to 50%–70%.
Q345NS Steel Plate Tolerance
| Item | Tolerance |
|---|---|
| Thickness Tolerance | ±0.3 mm (≤10 mm) / ±0.5 mm (10–50 mm) / ±1.0 mm (50–120 mm) |
| Width Tolerance | 0 / +10 mm |
| Length Tolerance | 0 / +15 mm (cut-to-length condition) |
| Flatness Tolerance | ≤ 5 mm/m (depends on thickness and rolling condition) |
| Diagonal Tolerance | ≤ 10 mm (standard plates) |
| Edge Deviation | Slight irregularity allowed for flame-cut or sheared edges |
| Surface Quality | No cracks, no delamination, minor rolling marks acceptable |
| Weight Tolerance | ±5% (theoretical weight basis) |
Q345NS Steel Plate Stock List
| Thickness (mm) | Standard Width (mm) | Standard Length (mm) | Stock Status | Weight Range (per sheet) |
|---|---|---|---|---|
| 6 mm | 1500 / 1800 / 2000 | 6000 / 12000 | In Stock | ~280 – 560 kg |
| 8 mm | 1500 / 1800 / 2000 | 6000 / 12000 | In Stock | ~370 – 740 kg |
| 10 mm | 1500 / 1800 / 2000 | 6000 / 12000 | In Stock | ~460 – 920 kg |
| 12 mm | 1500 / 1800 / 2000 | 6000 / 12000 | In Stock | ~560 – 1120 kg |
| 14 mm | 1500 / 1800 / 2000 | 6000 / 12000 | In Stock | ~650 – 1300 kg |
| 16 mm | 1500 / 1800 / 2000 | 6000 / 12000 | In Stock | ~740 – 1480 kg |
| 20 mm | 1500 / 1800 / 2000 | 6000 / 12000 | In Stock | ~930 – 1860 kg |
| 25 mm | 1500 / 1800 / 2000 | 6000 / 12000 | Limited Stock | ~1160 – 2320 kg |
| 30 mm | 1500 / 1800 / 2000 | 6000 / 12000 | Limited Stock | ~1390 – 2780 kg |
| 40 mm | 1500 / 1800 / 2000 | 6000 / 12000 | Made to Order | ~1850 – 3700 kg |
| 50 mm | 1500 / 1800 / 2000 | 6000 / 12000 | Made to Order | ~2320 – 4640 kg |
| 60 mm – 120 mm | Customized | Customized | Made to Order | Depends on specification |
If you require Q345NS steel plates in different thicknesses, widths, or custom sizes, contact us today for competitive pricing and tailored solutions.
Contact now to get the the Q345NS steel plates Stock List
What is difference between the Q345B and Q345NS steel plate
Q345B is a general structural steel with no special corrosion resistance, while Q345NS is designed for sulfuric acid dew point corrosion environments.
Compared with Q345B, Q345NS can reduce corrosion rate by about 50%–70% in flue gas systems and extend service life by approximately 2–3 times, especially in boilers, economizers, and acidic condensation conditions.
Q345NS Steel Plate Common Applications in Power Plant Chimneys
Q345NS steel plate is widely used in power plant chimney systems, especially in areas exposed to low-temperature flue gas and severe sulfuric acid dew point corrosion.
It is commonly applied in chimney inner linings, structural supports, flue gas ducts, and economizer outlet sections where acidic condensation is prone to occur.
With stable mechanical properties (yield strength ≥ 345 MPa, tensile strength 470–630 MPa) and excellent resistance to sulfuric acid dew point corrosion, Q345NS effectively prevents wall thinning, perforation, and structural failure caused by acidic condensate.
Compared with ordinary carbon steel (such as Q235B or Q345B), Q345NS can extend service life by approximately 2–3 times, while significantly outperforming conventional wear-resistant steels in acidic corrosion environments, where wear steels are typically not designed for chemical corrosion resistance.
This greatly improves the operational safety and durability of chimney systems and reduces maintenance frequency and unplanned shutdown losses in power plants.
Severe sulfuric acid dew point corrosion in power plant chimneys? Q345NS steel plates provide a reliable solution for long-term protection.
Processing Services for Q345NS Steel Plate
We provide a full range of customized processing services for Q345NS steel plates, and we can provide cutting, beveling, leveling, press bending and customized fabrication services for Q345NS steel plates according to your project requirements.
Q345NS Steel Plate Testing
We provide full quality inspection for Q345NS steel plates, including chemical analysis, mechanical testing, microstructure evaluation, ultrasonic testing, dimensional inspection, and optional corrosion performance testing to ensure reliable performance in sulfuric acid dew point corrosion environments.
Packaging Specifications of Q345NS acid dew point corrosion resistant steel plates
Q345NS steel plates are packed in seaworthy export packing with waterproof protection, steel strapping, and wooden reinforcement to ensure safe delivery worldwide.
