Cronite 34Ni/25Cr/Nb No. HR 33 Nb,Werkstoff 1.4852,E FORU

### **Cronite 34Ni/25Cr/Nb (Werkstoff 1.4852) - Heat-Resisting Nickel-Chromium-Niobium Alloy** #### **Overview** **Cronite 34Ni/25Cr/Nb** (designated as **HR 33 Nb** and standardized under **Werkstoff 1.4852**) is a high-performance, centrifugally cast nickel-chromium-iron alloy enhanced with niobium (Nb). It is specifically engineered for superior performance in the most demanding high-temperature environments, particularly those involving cyclic conditions and aggressive atmospheres. This alloy builds upon the foundation of classic heat-resistant steels by optimizing its composition. The balanced nickel content provides excellent resistance to carburization and thermal cycling, while the high chromium content ensures outstanding resistance to oxidation. The key differentiator is the addition of **niobium**, which stabilizes the alloy against sensitization and significantly improves its high-temperature strength and creep resistance. It is a premier material for high-load applications in industrial thermal processing. --- #### **Chemical Composition (Weight % - Typical)** The chemical composition is precisely controlled to maximize high-temperature stability and mechanical properties. | Element | Content (%) | | :--- | :--- | | **Nickel (Ni)** | **33.0 - 36.0** | | **Chromium (Cr)** | **24.0 - 26.0** | | **Iron (Fe)** | **Balance** | | **Niobium (Nb) [and Tantalum Ta]** | **0.8 - 1.5** | | **Silicon (Si)** | **1.3 - 2.0** | | **Carbon (C)** | **0.35 - 0.50** | | **Manganese (Mn)** | **≤ 1.5** | | **Other Elements** | ≤ 1.0 | * **Nickel (Ni):** Imparts fundamental resistance to carburization and thermal shock, and stabilizes the austenitic structure. * **Chromium (Cr):** Provides exceptional resistance to oxidation (scaling) and sulfidation by forming a durable, self-healing chromium oxide (Cr₂O₃) scale. * **Niobium (Nb):** The critical alloying element. It forms stable carbides (NbC), which pin grain boundaries and dramatically enhance creep rupture strength and resistance to deformation under load at high temperatures. It also prevents sensitization. * **Silicon (Si):** Synergistically works with chromium to improve the spallation resistance of the oxide scale under severe thermal cycling conditions. --- #### **Physical & Mechanical Properties** The following table outlines the key properties of Werkstoff 1.4852. | Property | Value / Description | | :--- | :--- | | **Density** | ~7.9 g/cm³ | | **Melting Range** | ~1380 - 1420 °C (2515 - 2590 °F) | | **Specific Heat (20°C)** | ~500 J/kg·K | | **Thermal Conductivity** | ~13.5 W/m·K (at 20°C) | | **Mean Coefficient of Thermal Expansion** | ~16.0 μm/m·°C (20-1000°C) | | **Tensile Strength (Room Temp)** | ~600 - 750 MPa | | **Yield Strength (Room Temp)** | ~350 - 450 MPa | | **Elongation (Room Temp)** | ~10 - 20% | | **High-Temperature Capability** | Excellent oxidation resistance up to **1180°C** (2150°F). Superior load-bearing capacity and creep resistance up to ~1150°C. | --- #### **Key Characteristics & Applications** **Key Characteristics:** 1. **Superior High-Temperature Strength:** The niobium addition provides exceptional creep rupture strength and resistance to deformation under mechanical load at temperatures up to 1150°C. 2. **Outstanding Oxidation Resistance:** Can withstand continuous operating temperatures up to 1180°C in oxidizing atmospheres. 3. **Excellent Resistance to Carburization:** The high nickel content effectively resists carbon penetration, preventing embrittlement and maintaining ductility in carburizing environments. 4. **Enhanced Thermal Fatigue Resistance:** Performs reliably under severe and rapid thermal cycling, making it ideal for batch-type and cyclic furnace operations. 5. **Good Castability and Weldability:** Primarily used in cast form, allowing for the manufacture of complex components. It can be repaired or fabricated using specialized welding procedures. **Typical Applications:** This alloy is predominantly used in the centrifugally cast form for the most critical components in high-temperature furnaces. * **Radiant Tubes (All Types):** Especially for high-temperature carburizing, carbonitriding, and neutral hardening furnaces where resistance to sagging and creep deformation is critical. * **Retorts & Muffles:** For creating protective atmospheres in processes running at the upper end of the temperature spectrum. * **Roller Hearth Furnace Rolls:** Must withstand high loads at temperature without distortion. * **Fixture Components:** Baskets, trays, and grids for carrying workloads in high-temperature heat treatment processes. * **Transfer Arms and Belts:** In high-temperature sintering and brazing furnaces. * **Heat Treatment Jigs and Supports:** For applications where mechanical strength at temperature is paramount. --- #### **International Standards** "Cronite 34Ni/25Cr/Nb" or "HR 33 Nb" is a proprietary alloy whose specifications are precisely defined by the **Werkstoff 1.4852** number. It has very close equivalents in European casting standards. | Region / Standard | Designation | Description | | :--- | :--- | :--- | | **Germany / EU** | **Werkstoff 1.4852** | The primary material number for this specific cast alloy. | | **Trade Name** | **Cronite HR 33 Nb** or **34Ni/25Cr/Nb** | Common industry names. | | **Europe (Cast)** | **EN 10295, Grade G-X40NiCrNb35-25** | This is the direct and standardized European designation for the cast equivalent of Werkstoff 1.4852. This is the most relevant standard for procurement. | | **USA (Cast)** | **-** | There is no direct ASTM equivalent. The closest general-purpose grade is ASTM A297 "HK", but it lacks the niobium enhancement and has lower high-temperature strength. | | **USA (Wrought)** | **UNS N06625 / Alloy 625** | While not equivalent, the wrought Alloy 625 is also a niobium-strengthened Ni-Cr alloy. However, Alloy 625 has a much higher Ni content and is used for even more severe corrosive and high-temperature applications. | | **Similar Cast Alloy** | **NiCr 50 Nb / G-X40NiCrNb50-25** | This is a higher nickel (~50%) version with similar Cr and Nb, used for even more severe carburizing resistance. | **Important Note:** For engineering and procurement, the most accurate specifications to use are the proprietary **Cronite HR 33 Nb** or the standardized European casting designation **G-X40NiCrNb35-25** (based on EN 10295), which corresponds to **Werkstoff 1.4852**. --- #### **Summary** In summary, **Cronite 34Ni/25Cr/Nb (Werkstoff 1.4852 / G-X40NiCrNb35-25)** represents an advanced class of heat-resistant cast alloys where niobium stabilization is used to achieve superior high-temperature mechanical properties. It is the material of choice for critical furnace components like radiant tubes and rollers that must withstand a combination of extreme temperatures, mechanical load, and aggressive atmospheres without deforming or failing. Its excellent balance of oxidation resistance, carburization resistance, and unparalleled creep strength makes it a cornerstone alloy for high-end thermal processing equipment.

Packing of Standard Packing: Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and steel drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 3198 gallon liquid totes Special package is available on request.