Cronite 37Ni/18Cr No. HR5,Cronite 37/18; Werkstoff 1.4865,E FORU

### **Cronite 37Ni/18Cr (Werkstoff 1.4865) - Heat-Resisting Nickel-Chromium Alloy** #### **Overview** **Cronite 37Ni/18Cr** (commonly known as **37/18** and standardized under **Werkstoff 1.4865**) is a classic nickel-chromium-iron alloy designed for exceptional high-temperature service. It belongs to a family of cast heat-resistant alloys renowned for their strength, stability, and resistance to oxidation and carburization at temperatures exceeding 1000°C. This alloy derives its performance from a high nickel content, which provides inherent resistance to carburization and thermal cycling, and a significant chromium content, which forms a tenacious, self-healing chromium oxide (Cr₂O₃) scale for protection against oxidizing atmospheres. It is a premier material for demanding industrial heating applications, particularly in the heat treatment sector. --- #### **Chemical Composition (Weight % - Typical)** The chemical composition is balanced for optimal high-temperature performance. | Element | Content (%) | | :--- | :--- | | **Nickel (Ni)** | **34.0 - 37.0** | | **Chromium (Cr)** | **17.0 - 19.0** | | **Iron (Fe)** | **Balance** | | **Silicon (Si)** | **1.5 - 2.5** | | **Carbon (C)** | **0.35 - 0.55** | | **Manganese (Mn)** | **≤ 1.5** | | **Other Elements** | ≤ 1.0 | * **Nickel (Ni):** Provides excellent resistance to carburization and thermal shock, and stabilizes the austenitic matrix. * **Chromium (Cr):** Imparts outstanding resistance to oxidation (scaling) and sulfidation by forming a protective surface layer. * **Silicon (Si):** Enhances the scaling resistance, particularly under cyclic temperature conditions, by improving the adhesion of the oxide scale. * **Carbon (C):** Provides high-temperature strength through solid solution strengthening and carbide formation. --- #### **Physical & Mechanical Properties** The following table outlines the key properties of Werkstoff 1.4865. | Property | Value / Description | | :--- | :--- | | **Density** | 7.8 - 7.9 g/cm³ | | **Melting Range** | ~1400 °C (2550 °F) | | **Specific Heat (20°C)** | ~500 J/kg·K | | **Thermal Conductivity** | ~14 W/m·K (at 20°C) | | **Mean Coefficient of Thermal Expansion** | ~16.5 μm/m·°C (20-1000°C) | | **Tensile Strength (Room Temp)** | ~550 - 700 MPa | | **Yield Strength (Room Temp)** | ~300 - 400 MPa | | **Elongation (Room Temp)** | ~8 - 15% | | **High-Temperature Capability** | Excellent oxidation resistance up to **1150°C** (2100°F). Good load-bearing capacity up to ~1050°C. | --- #### **Key Characteristics & Applications** **Key Characteristics:** 1. **Exceptional Oxidation Resistance:** Can withstand continuous operating temperatures up to 1150°C, making it suitable for direct exposure to air and combustion gases. 2. **Excellent Resistance to Carburization:** The high nickel content makes it highly resistant to carbon penetration, which prevents embrittlement and failure in carburizing atmospheres. 3. **Good Creep Strength:** Maintains its mechanical strength under load at high temperatures. 4. **Resistance to Thermal Fatigue:** Performs well under repeated heating and cooling cycles, a common requirement in batch-type furnaces. 5. **Good Castability:** It is primarily a cast alloy, allowing for the production of complex and intricate components like radiant tubes and fixtures. **Typical Applications:** This alloy is predominantly used in the cast form for critical components in industrial furnaces and heat treatment equipment: * **Radiant Tubes:** For indirect heating in carburizing, carbonitriding, and neutral hardening furnaces. * **Retorts & Muffles:** Enclosed containers that create a protective atmosphere for the workload. * **Furnace Rollers:** Conveying components that must withstand high loads and temperatures. * **Fixtures, Baskets, and Trays:** For holding components during heat treatment processes (e.g., carburizing, annealing). * **Heat Treatment Jigs:** Structural supports within high-temperature furnaces. * **Transfer Rolls:** In high-temperature kilns and furnaces. --- #### **International Standards** "Cronite 37/18" is a well-established trade name, and **Werkstoff 1.4865** is its definitive German material number. While it does not have a direct, single-number equivalent in the ASTM system, it is chemically and functionally very similar to several standard cast grades. Its closest wrought (wrought: forged or rolled) analogue is Alloy 330. | Region / Standard | Designation | Description | | :--- | :--- | :--- | | **Germany / EU** | **Werkstoff 1.4865** | The primary material number for this specific composition. | | **Trade Name** | **Cronite 37/18** or **37Ni/18Cr** | Common industry names. | | **USA (Cast)** | **ASTM A297, Grade HH** | The chemistry of HH (Ni 24-28, Cr 24-28, C 0.35-0.75) is different, but it serves in a similar high-temperature, cast application realm. Cronite 37/18 has a unique, proprietary composition. | | **USA (Cast)** | **ASTM A608, Grade HK30** | HK30 is a lower-nickel (15-22% Ni) alternative. Cronite 37/18 offers superior carburization resistance. | | **USA (Wrought)** | **UNS N08330 / Alloy 330** | The wrought alloy (35Ni/19Cr) with a very similar composition is often used for similar high-temperature applications in sheet, bar, or tube form. | | **Europe (Cast)** | **EN 10295, Grade G-X40NiCrSi35-18** | This is the European designation for a cast heat-resistant steel very close to the Cronite 37/18 composition. | **Important Note:** "Cronite 37/18" is a specific proprietary alloy from the Cronite Group. When specifying this material for procurement or design, it is most precise to use the trade name and/or the **Werkstoff 1.4865** number. For engineering drawings, the chemically similar and standardized **G-X40NiCrSi35-18** is often used. --- #### **Summary** In summary, **Cronite 37Ni/18Cr (Werkstoff 1.4865)** is a high-performance, nickel-chromium cast alloy engineered for the most demanding high-temperature environments. Its superior resistance to oxidation and carburization, combined with good structural strength, makes it an indispensable material for critical furnace components like radiant tubes, retorts, and fixtures in the heat treatment, metallurgical, and ceramic industries. While it is a proprietary alloy, its specifications are well-understood within the industry through the **1.4865** designation and its close alignment with standards like **G-X40NiCrSi35-18**.

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 3197 gallon liquid totes Special package is available on request.