Altemp 718 Nickel-Base Superalloy,DIN 2.4668; 1

### **Product Datasheet: Altemp 718 / INCONEL® 718 (UNS N07718)** **A Precipitation-Hardenable Nickel-Chromium Superalloy for High-Temperature Applications** --- #### **1. Overview** **Altemp 718**, commercially known as **INCONEL® 718**, is a precipitation-hardenable nickel-chromium alloy containing significant amounts of iron, niobium, and molybdenum. The alloy derives its strength from the precipitation of gamma prime (γ') and gamma double prime (γ'') phases during aging treatments, with the latter being the primary strengthening phase. This alloy is characterized by a combination of high strength, excellent creep resistance, and good stability at temperatures up to 700°C (1300°F). It exhibits outstanding weldability and post-weld aging response without susceptibility to strain-age cracking, making it particularly valuable for applications requiring complex fabrication and welding operations. --- #### **2. Chemical Composition (Typical Weight %)** | Element | Content (%) | Role in the Alloy | | :--- | :--- | :--- | | **Nickel (Ni)** | Balance (~50.0-55.0) | Forms the austenitic matrix | | **Chromium (Cr)** | ~17.0-21.0 | Provides oxidation and corrosion resistance | | **Iron (Fe)** | ~16.0-20.0 | Major alloying element, provides cost-effective strengthening | | **Niobium (Nb)** | ~4.75-5.50 | Primary strengthening element through γ'' formation | | **Molybdenum (Mo)** | ~2.80-3.30 | Provides solid solution strengthening | | **Titanium (Ti)** | ~0.65-1.15 | Contributes to γ' precipitation | | **Aluminum (Al)** | ~0.20-0.80 | Contributes to γ' precipitation | | **Cobalt (Co)** | ≤ 1.00 | Residual element | | **Carbon (C)** | ≤ 0.08 | Controlled for carbide formation | --- #### **3. Physical Properties (Typical)** | Property | Value / Condition | | :--- | :--- | | **Density** | 8.19 g/cm³ (0.296 lb/in³) | | **Melting Range** | 1260-1336 °C (2300-2440 °F) | | **Thermal Expansion Coefficient** | 13.0 μm/m·°C (20-100°C) | | **Thermal Conductivity** | 11.4 W/m·K (at 100°C) | | **Modulus of Elasticity** | 204 GPa (29.5×10⁶ psi) | | **Electrical Resistivity** | 1.25 μΩ·m | --- #### **4. Mechanical Properties** **Solution Annealed & Aged Condition:** * **Tensile Strength**: 1310 MPa (190 ksi) min * **Yield Strength (0.2% Offset)**: 1035 MPa (150 ksi) min * **Elongation**: 12% min * **Reduction of Area**: 15% min **High-Temperature Capability:** * Excellent strength retention up to 650°C (1200°F) * Good creep and stress-rupture properties * Maintains mechanical properties in long-term service --- #### **5. Heat Treatment** Standard heat treatment typically includes: * **Solution Treatment**: 950-980°C (1750-1800°F) * **Aging**: 720°C (1325°F) for 8 hours, furnace cool to 620°C (1150°F) * **Hold**: 620°C (1150°F) for 8 hours, air cool --- #### **6. Product Applications** **Aerospace Industry:** * Gas turbine engine components * Compressor and turbine discs * Shafts, spacers, and casings * Afterburner components * Rocket engine parts **Power Generation:** * Gas turbine components * Nuclear reactor core components * High-temperature fasteners **Oil and Gas:** * Downhole well components * High-strength fasteners * Valve components **Other Applications:** * High-temperature tooling * Chemical processing equipment * Structural components in high-temperature environments --- #### **7. International Standards** * **DIN/Werkstoff Nr.**: 2.4668 * **ASTM Specifications**: * **ASTM B-670**: Precipitation-Hardened Nickel Alloy Plate, Sheet, and Strip * **Aerospace Material Specifications**: * **AMS 5596**: Sheet, Strip, and Plate * **AMS 5597**: Sheet, Strip, and Plate * **AMS 5662**: Bars, Forgings, and Rings * **AMS 5663**: Bars, Forgings, and Rings * **Additional Certifications**: * ASME Boiler and Pressure Vessel Code * ISO 15156/NACE MR0175 * Various military and aerospace specifications --- **Technical Note:** The information provided represents typical values and characteristics. Actual properties may vary based on manufacturing processes, heat treatment parameters, and specific product form. For critical applications, consult the most recent edition of relevant material specifications and manufacturer's technical data. *INCONEL is a registered trademark of Special Metals Corporation. Altemp 718 is understood to be a related designation for this alloy composition.*

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 3383 gallon liquid totes Special package is available on request.