HASTELLOY S Severe Corrosion and Heat Resistant Alloy, Wrought UNS N06635; ，1

### **Product Introduction: HASTELLOY® S (UNS N06635) Severe Corrosion and Heat Resistant Alloy** **Overview** HASTELLOY® S is a nickel-chromium-molybdenum alloy specifically engineered for exceptional high-temperature strength and stability. Its primary distinction lies in its outstanding resistance to oxidation and stress-corrosion cracking, coupled with low susceptibility to embrittlement after long-term exposure in the 1200°F to 1800°F (650°C to 980°C) range. Unlike many other high-temperature alloys, HASTELLOY S was formulated to maintain its ductility and toughness after aging, making it an ideal solution for demanding industrial heating, chemical processing, and aerospace applications where thermal cycling is common. --- #### **Chemical Composition (Typical % by Weight)** The composition of HASTELLOY S is meticulously balanced to optimize high-temperature performance and stability. | Element | Content (%) | Role & Benefit | | :--- | :--- | :--- | | **Nickel (Ni)** | Balance | Provides the fundamental austenitic matrix, ensuring high metallurgical stability and strength at elevated temperatures. | | **Chromium (Cr)** | 14.0 - 16.0 | Imparts resistance to oxidizing environments and high-temperature oxidation by forming a protective chromium oxide scale. | | **Molybdenum (Mo)** | 14.0 - 16.0 | Provides solid solution strengthening and enhances resistance to reducing acids and localized corrosion. Critical for high-temperature creep strength. | | **Tungsten (W)** | ~ 1.0 | Contributes to solid solution strengthening at high temperatures. | | **Iron (Fe)** | 3.0 max | Kept at a low level to minimize detrimental phase formation and maintain corrosion resistance. | | **Cobalt (Co)** | 2.0 max | A residual element controlled to ensure consistent properties. | | **Manganese (Mn)**| 1.00 max | Aids in manufacturability. | | **Silicon (Si)** | 1.00 max | Enhances resistance to oxidation. | | **Carbon (C)** | 0.02 max | Kept very low to minimize carbide precipitation during prolonged high-temperature exposure, which is key to maintaining ductility. | | **Lanthanum (La)** | 0.02 - 0.12 | A critical addition that significantly improves the adhesion and spallation resistance of the protective oxide scale under cyclic heating and cooling conditions. | *Note: "HASTELLOY®" is a registered trademark of Haynes International Inc.* --- #### **Physical & Mechanical Properties (Typical)** | Property | Value / Condition | | :--- | :--- | | **Density** | 8.84 g/cm³ (0.319 lb/in³) | | **Melting Range** | 1330 - 1380 °C (2425 - 2515 °F) | | **Thermal Expansion Coefficient** | 12.3 μm/m·°C (6.8 μin/in·°F) @ 20-100°C | | **Tensile Strength (Room Temp)** | 760 MPa (110 ksi) min | | **Yield Strength (0.2% Offset, Room Temp)** | 310 MPa (45 ksi) min | | **Elongation (Room Temp)** | 35% min | --- #### **International Standards and Specifications** HASTELLOY S is covered by several key international standards for wrought products. * **ASTM B575:** Standard Specification for Low-Carbon Nickel-Molybdenum-Chromium, Nickel-Chromium-Iron, Nickel-Chromium-Cobalt-Molybdenum, and Nickel-Chromium-Molybdenum-Tungsten Alloy Plate, Sheet, and Strip. (This is the primary ASTM standard for sheet and plate forms). * **AMS 5754:** Aerospace Material Specification for the alloy, ensuring quality for critical aviation and aerospace components. * **UNS N06635:** Unified Numbering System designation. * **DIN 2.4835:** The corresponding material number in the German standard. --- #### **Product Applications** HASTELLOY S is selected for its superior stability and strength in high-temperature environments, particularly where thermal cycling is a concern. 1. **Industrial Furnaces & Heat Treatment:** * Radiant tubes, muffles, and retorts. * Heat treatment baskets and fixtures. * Components for brazing and sintering furnaces. 2. **Aerospace & Gas Turbines:** * Combustion chamber components, liners, and afterburner parts. * Turbine seals and rings requiring stability under thermal cycling. 3. **Chemical Process Industry:** * Components in processes involving catalytic reforming and hydrocarbon cracking. * Equipment exposed to mixed acids and other corrosive environments at elevated temperatures, especially where resistance to stress-corrosion cracking is critical. 4. **Pollution Control:** * Thermal reactor components in systems that process waste gases at high temperatures. #### **Key Advantages** * **Exceptional High-Temperature Stability:** Resists embrittlement after long-term aging in the 650°C to 980°C range, a common failure mode for other alloys. * **Superior Oxidation Resistance:** The combination of chromium and lanthanum provides outstanding resistance to scale formation and spallation under cyclic temperature conditions. * **Good Mechanical Strength:** Maintains high strength and excellent creep resistance at elevated temperatures. * **Resistance to Stress-Corrosion Cracking (SCC):** Offers good performance in chloride-containing environments where SCC is a risk. **Conclusion** HASTELLOY® S (UNS N06635) is a premium, high-temperature alloy designed for applications where long-term thermal stability and resistance to oxidation are paramount. Its low-carbon chemistry and unique lanthanum addition make it exceptionally resistant to the embrittlement and scale spallation that plague other materials in cyclic service. For critical components in industrial heating, aerospace, and chemical processing, HASTELLOY S provides a reliable and durable solution, backed by international standards like ASTM B575 and AMS 5754.

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 3396 gallon liquid totes Special package is available on request.