718 Cast UNS N07718 Severe Corrosion and Heat Resistant Alloy,Cast UNS N07718; 1

### **Product Introduction: Alloy 718 Cast (UNS N07718) High-Strength, Corrosion and Heat Resistant Superalloy** **Overview** Cast Alloy 718, designated as UNS N07718, is a precipitation-hardenable nickel-chromium superalloy containing significant amounts of iron, niobium, and molybdenum. It is the cast equivalent of the legendary wrought alloy UNS N07718 (INCONEL® 718), one of the most widely used superalloys in the world. This alloy is renowned for its exceptional combination of high yield, tensile, and creep-rupture strength up to 700°C (1300°F), good fatigue resistance, and excellent corrosion resistance. A key characteristic of Alloy 718 is its outstanding weldability and the fact that it can be precipitation hardened without suffering from post-weld strain-age cracking, a common issue with other high-strength superalloys. This makes it an indispensable material for the most demanding structural applications in aerospace, energy, and oil & gas industries. --- #### **Chemical Composition (Typical % by Weight)** The composition of Cast Alloy 718 is engineered for optimal precipitation hardening and stability. | Element | Content (%) | Role & Benefit | | :--- | :--- | :--- | | **Nickel (Ni)** | 50.0 - 55.0 | Forms the austenitic matrix, providing the fundamental structure for high-temperature strength. | | **Chromium (Cr)** | 17.0 - 21.0 | Confers resistance to oxidation and corrosion. | | **Iron (Fe)** | Balance | The primary alloying element, which helps control cost and contributes to solid solution strengthening. | | **Niobium (Nb)** | 4.75 - 5.50 | **The key strengthening element.** It combines with nickel to form the metastable gamma double prime (γ") phase, Ni₃Nb, which is the primary source of the alloy's exceptional strength. | | **Molybdenum (Mo)** | 2.80 - 3.30 | Provides solid-solution strengthening and enhances resistance to pitting and crevice corrosion. | | **Titanium (Ti)** | 0.65 - 1.15 | Contributes to strengthening by forming the gamma prime (γ') phase, Ni₃(Al,Ti), which works synergistically with the γ" phase. | | **Aluminum (Al)** | 0.20 - 0.80 | Works with Titanium to form the gamma prime (γ') phase. | | **Cobalt (Co)** | 1.00 max | A residual element. | | **Carbon (C)** | 0.08 max | Forms strengthening carbides. | | **Manganese (Mn)**| 0.35 max | Aids in manufacturability. | | **Silicon (Si)** | 0.35 max | A deoxidizer in the casting process. | | **Boron (B)** | 0.006 max | Enhances creep strength and ductility. | | **Phosphorus (P)**| 0.015 max | Kept low to ensure good ductility. | | **Sulfur (S)** | 0.015 max | A detrimental element kept to an absolute minimum. | *Note: "INCONEL" is a registered trademark of Special Metals Corporation.* --- #### **Physical & Mechanical Properties (Typical - After Full Heat Treatment)** | Property | Value / Condition | | :--- | :--- | | **Density** | 8.19 g/cm³ (0.296 lb/in³) | | **Melting Range** | 1260 - 1336 °C (2300 - 2440 °F) | | **Thermal Expansion** | 13.0 μm/m·°C (7.2 μin/in·°F) @ 20-100°C | | **Tensile Strength (Room Temp)** | 1240 MPa (180 ksi) min | | **Yield Strength (0.2% Offset, Room Temp)** | 1030 MPa (150 ksi) min | | **Elongation (Room Temp)** | 12% min | *Note: Mechanical properties are highly dependent on the specific heat treatment cycle (e.g., Solution Treatment + Aging).* --- #### **International Standards and Specifications** Cast Alloy 718 is specified by the most stringent international standards for high-integrity applications. * **Cast Product Standards:** * **AMS 5383:** Aerospace Material Specification for investment castings, covering the stringent requirements for vacuum-melted alloy 718 castings. * **ASTM NACE MR0175 / ISO 15156:** This alloy is qualified and approved for use in sour service (H₂S-containing) environments in the oil and gas industry. * **UNS N07718:** Unified Numbering System designation for both cast and wrought forms. * **Wrought Equivalent:** * **UNS N07718 (INCONEL 718):** The standard wrought form. * **AMS 5662 / AMS 5663:** Standards for wrought nickel alloy bar, forgings, and ring. * **ASTM B637:** Standard Specification for Precipitation-Hardening Nickel Alloy Bars, Forgings, and Forging Stock. --- #### **Product Applications** Cast Alloy 718 is a critical material for high-stress components operating in demanding environments. 1. **Aerospace & Gas Turbines:** * **Jet Engine Components:** Turbine wheels, integrally cast rotors, compressor cases, frames, and housings. * **Rocket Engines:** Turbopump housings, thrust chambers, and liquid-fueled rocket components. * **Fasteners:** High-strength bolts and studs. 2. **Oil & Gas:** * **Downhole Tools:** Components for Measurement-While-Drilling (MWD) and Logging-While-Drilling (LWD) tools. * **Wellhead & Christmas Tree Components:** Valves, hangers, and seals for high-pressure, high-temperature (HPHT) wells. * **Subsea Equipment:** Components requiring high strength and corrosion resistance in sour service. 3. **Power Generation:** * Turbine blades, disks, and structural components in industrial gas turbines. #### **Key Advantages** * **Exceptional High Strength:** Achieves the highest strength levels of any commercial precipitation-hardenable nickel alloy in its service temperature range (up to 700°C). * **Outstanding Weldability:** Unlike many other precipitation-hardened superalloys, it is highly resistant to strain-age cracking after welding, allowing for the fabrication and repair of complex cast structures. * **Excellent Comprehensive Properties:** Offers a superior balance of strength, ductility, fatigue life, and creep rupture strength. * **Good Corrosion Resistance:** Resists oxidation and corrosion in a wide variety of environments, a performance that is further enhanced by its high strength. **Conclusion** Cast Alloy 718 (UNS N07718) is a premier precipitation-hardenable nickel-based superalloy that has become the benchmark for high-strength applications in extreme environments. Its unique niobium-strengthening mechanism, which grants it both phenomenal strength and unparalleled weldability, makes it the material of choice for the most critical components in aerospace propulsion, advanced energy systems, and HPHT oil and gas production. Its compliance with rigorous standards like AMS 5383 and NACE MR0175 ensures the highest level of quality and reliability for engineered cast solutions.

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 3402 gallon liquid totes Special package is available on request.