Product Overview
In the demanding environment of industrial biomass boilers, waste incineration plants, and power station CFB boilers, the reliability of your combustion system hinges on one critical component: the Boiler Grate.
Our ZG40Cr25Ni20Si2 Precision Casting Boiler Grate is engineered for extreme thermal stress. Manufactured via advanced silica sol precision casting (investment casting) technology, this product is designed to deliver superior structural integrity where conventional cast iron or lower-grade heat-resistant steel components fail. As a professional heat-resistant steel casting solution, this grate offers a perfect balance between mechanical strength and chemical stability under continuous high-temperature operation.
Key Specifications & Material Advantages
This product utilizes the ZG40Cr25Ni20Si2 (equivalent to UNS J94204 / HH40) austenitic heat-resistant steel. The selection of this specific high chromium-nickel alloy is based on strict metallurgical requirements for boiler applications.
| Parameter | Description |
| Material Grade | ZG40Cr25Ni20Si2 / HH40 |
| Process Type | Silica Sol Investment Casting (Precision Casting) |
| Casting Tolerance | CT7-CT9 (GB/T 6414) / ISO 8062 |
| Max Service Temp | ≤ 1150°C (Continuous) |
| Surface Finish | Ra 6.3 – 12.5 µm (As-cast, no scaling) |
Chemical Composition & Standard
Unlike standard heat-resistant steels, the ZG40Cr25Ni20Si2 composition ensures a stable austenitic matrix:
Carbon (C)
0.35-0.45% – Provides high hardenability and wear resistance against fuel scouring.
Chromium (Cr)
24.0-27.0% – Forms a dense Cr₂O₃ oxide film, providing exceptional anti-oxidation properties up to 1150°C.
Nickel (Ni)
19.0-22.0% – Stabilizes the austenitic structure, prevents embrittlement, and resists thermal fatigue cracking.
Silicon (Si)
1.5-2.5% – Enhances castability and further improves high-temperature corrosion resistance.
Why Precision Casting for Boiler Grates?
Traditional sand casting often results in surface porosity, dimensional inaccuracies, and internal inclusions that become stress concentration points under thermal cycling. Our precision casting process eliminates these risks:
Dimensional Accuracy
Direct casting of complex interlocking geometries required for chain grate stokers without extensive machining.
Superior Surface Quality
The smooth surface reduces slag adhesion, ensuring consistent air distribution across the combustion chamber.
Consistent Metallurgy
The investment casting process ensures a fine-grained structure, critical for thermal shock resistance during boiler start-up and shut-down cycles.
Performance Characteristics (Backed by Metallurgical Facts)
High-Temperature Strength
The combination of Cr and Ni provides a high creep rupture strength. Unlike ferritic steels, this austenitic grade maintains its load-bearing capacity even when the surface temperature exceeds 900°C.
Thermal Fatigue Resistance
In waste-to-energy plants, temperature fluctuations are constant. This grade offers superior resistance to "fire cracking" compared to standard 1.4848 (HK40) or similar grades, reducing unplanned downtime for replacements.
Oxidation and Corrosion Resistance
The high silicon (Si) content specifically enhances resistance to sulfurous atmospheres and alkali metal chlorides commonly found in biomass fuel combustion.
why choose us
This ZG40Cr25Ni20Si2 precision casting boiler grate is the optimal replacement part for:
- Biomass Power Plants: Ideal for burning wood chips, rice husks, and palm kernel shells.
- Municipal Solid Waste (MSW) Incinerators: Withstands the corrosive ash environment.
- Industrial Boilers: Suitable for traveling grate stokers and reciprocating grate feeders.
- Metallurgical & Chemical Furnaces: Where high-temperature conveying components are required.
Company Advantages
While many foundries can produce heat-resistant castings, our value lies in process control and material traceability. We are not just a supplier; we are a manufacturing partner for boiler spare parts.
Strict Material Traceability
Every batch of raw material is subjected to spectrometer analysis (PMI) before melting. We guarantee the chemical composition meets the ZG40Cr25Ni20Si2 standard, ensuring that the high nickel-chromium content is precisely maintained to meet your required service life.
Advanced Silica Sol Casting Line
Unlike competitors still using outdated water glass processes, our silica sol investment casting line produces castings with superior surface finish and dimensional stability. This minimizes the need for post-installation grinding, ensuring that the boiler grate bars fit perfectly into the existing stoker frame.
Optimized Heat Treatment
To unlock the full potential of the austenitic stainless steel grade, we implement a strict solution treatment (water quenching after holding at 1050°C-1100°C). This eliminates carbide precipitation at grain boundaries, maximizing corrosion resistance and ductility-a step often skipped by low-cost manufacturers to save energy.
Rapid Response & Short Lead Times
We understand that boiler downtime costs thousands of dollars per hour. We maintain a stock of raw materials specifically for the ZG40Cr25Ni20Si2 grade. For standard sizes, our lead time is 15-25 days. We also provide 3D scanning services to ensure replacement parts match your original equipment manufacturer (OEM) specifications perfectly.
Quality Assurance
All precision casting boiler grates undergo:
- NDT (Non-Destructive Testing): Visual inspection and dye penetrant testing for surface defects.
- Dimension Report: Full inspection report with each shipment.
- Mechanical Test: Tensile strength and hardness tests per batch.
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