Hastelloy G-35 Nickel Alloy, G-35 alloy，1

### **Introduction to Hastelloy® G-35® (UNS N06035) Nickel Alloy** **Hastelloy® G-35®** is a nickel-chromium-iron-molybdenum alloy specifically developed as a superior alternative to earlier "G-type" alloys like G-3 (UNS N06985) and G-30 (UNS N06030). Its primary design goal was to provide **exceptional resistance to phosphoric acid** and other strongly oxidizing chemicals, while also offering improved thermal stability and fabricability. A key innovation in G-35 is its optimized chemistry, which eliminates the formation of detrimental intermetallic phases, a problem that could plague earlier generations of these alloys during welding or high-temperature service. This makes G-35 highly reliable in the **as-welded condition**. --- ### **Chemical Composition (Weight %, typical)** The composition is carefully balanced to maximize corrosion resistance in oxidizing media without compromising stability. | Element | Minimum | Maximum | Key Function | | :--- | :--- | :--- | :--- | | **Nickel (Ni)** | **Balance** | | Provides the fundamental corrosion-resistant austenitic matrix. | | **Chromium (Cr)** | 32.0 | 35.0 | **Very high content** for superior resistance to oxidizing media. | | **Molybdenum (Mo)** | 7.0 | 9.0 | Provides resistance to reducing media and pitting/crevice corrosion. | | **Iron (Fe)** | 13.0 | 17.0 | Balances the structure and cost. | | **Cobalt (Co)** | - | 3.0 | Incidental element. | | **Tungsten (W)** | - | 1.0 | Incidental element; some solid solution strengthening. | | **Copper (Cu)** | 0.5 | 1.5 | Enhances resistance to sulfuric acid. | | **Manganese (Mn)** | - | 1.5 | - | | **Silicon (Si)** | - | 0.60 | - | | **Carbon (C)** | - | 0.03 | Kept low to prevent carbide precipitation. | | **Phosphorus (P)** | - | 0.04 | - | | **Sulfur (S)** | - | 0.03 | - | ***Key Differentiator:*** The high Chromium content (32-35%) is the standout feature, making it exceptionally resistant to oxidizing corrosives like nitric acid, chromic acid, and environments with ferric or cupric ions. --- ### **Physical Properties (Typical)** * **Density:** 8.22 g/cm³ (0.297 lb/in³) * **Melting Range:** 1330 - 1380 °C (2425 - 2510 °F) * **Thermal Expansion Coefficient:** 13.9 μm/m·°C (20-100°C) * **Thermal Conductivity:** 11.0 W/m·K at 100°C * **Modulus of Elasticity (Young's Modulus):** 200 GPa (29 x 10⁶ psi) at 21°C --- ### **Mechanical Properties (Typical at Room Temperature, Annealed Condition)** * **Tensile Strength:** ≥ 690 MPa (100 ksi) * **Yield Strength (0.2% Offset):** ≥ 310 MPa (45 ksi) * **Elongation:** ≥ 40% *These properties indicate good ductility and formability for manufacturing equipment.* --- ### **Key Characteristics and Product Applications** #### **Key Characteristics:** 1. **Outstanding Oxidizing Acid Resistance:** Excels in phosphoric acid, nitric acid, and sulfuric acid environments, particularly those contaminated with oxidizing impurities. 2. **Excellent Localized Corrosion Resistance:** Offers strong resistance to pitting and crevice corrosion in chloride-containing solutions. 3. **Superior Thermal Stability:** The chemistry is designed to resist the precipitation of harmful secondary phases (like mu and sigma) during exposure to high temperatures (e.g., in heat-affected zones from welding). This prevents "weld decay" and makes it suitable for use in the as-welded condition. 4. **Good Fabricability:** Can be readily formed and welded using standard techniques for nickel alloys. #### **Primary Applications:** Hastelloy G-35 is predominantly used in the chemical processing and related industries where oxidizing conditions are prevalent. * **Phosphoric Acid Production:** * **Evaporators, heat exchangers, and piping** in wet-process phosphoric acid plants. It is highly resistant to both the phosphoric acid and the aggressive halide impurities (e.g., fluorides, chlorides) found in phosphate rock. * **Sulfuric Acid Production & Handling:** * Components in acid coolers and pickling lines. * **Nitric Acid Production:** * Equipment handling nitric acid and mixtures. * **Nuclear Fuel Reprocessing:** * Handling nitric acid streams. * **Pulp & Paper Industry:** * Digester and bleaching system components exposed to oxidative environments. * **Flue Gas Desulfurization (FGD) Systems:** * Outlet ducts and other components where acidic condensates with chlorides form. --- ### **International Standards** Hastelloy G-35 is covered by several ASTM specifications for its various product forms. | Product Form | Standard | Designation | Notes | | :--- | :--- | :--- | :--- | | **Plate, Sheet, Strip** | ASTM B582 | UNS N06035 | Standard Specification for Nickel-Chromium-Iron-Molybdenum-Copper Alloy Plate, Sheet, and Strip. | | **Bar & Wire** | ASTM B581 | UNS N06035 | Standard Specification for Nickel-Chromium-Iron-Molybdenum-Copper Alloy Rod and Bar. | | **Pipe & Tube** | ASTM B622 / B619 | UNS N06035 | For seamless and welded pipe and tube. | | **Welding Consumables** | AWS A5.14 | **ERNiCrMo-9** | Matching composition filler metal for GTAW (TIG), GMAW (MIG), and SAW processes. | | **Welding Consumables** | AWS A5.11 | **ENiCrMo-9** | Matching composition covered electrodes for SMAW (Stick) welding. | **Note:** "Hastelloy" and "G-35" are registered trademarks of **Haynes International, Inc.** The information provided is for general reference. For critical applications, it is essential to consult the latest technical data sheets from the manufacturer and perform testing under specific process conditions.

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 3259 gallon liquid totes Special package is available on request.