Super alloys or high performance alloys have an ability to function at temperatures above 540ºC (1000ºF) with deformation resistance and high surface stability. As they have good oxidation and creep resistance, super alloys can be commonly forged, rolled to sheet or produced in various shapes. Iron-base, nickel-base and cobalt-base alloys are the major types of super alloys. Nickel-base and cobalt-base super alloys may be cast or wrought based on its composition or application. The iron-base super alloys are generally wrought alloys with stainless steel technology. These alloys can be strengthened by precipitation hardening, work hardening and solid-solution hardening.
The following section will provide details about Inconel 718 (UNS NO7718), which has superelastic formability, excellent corrosion resistance and high strength.
Chemical Composition
The following table shows the chemical composition of Super Alloy Inconel 718 (UNS NO7718) Seamless pipe.ElementsContent (%)Nickel, Ni50-55Chromium, Cr17 – 21Iron, Fe19Niobium, Nb (Columbium, Cb)4.75-5.25Molybdenum, Mo2.80-3.30Cobalt, Co≤ 1Titanium, Ti0.65-1.15Silicon, Si≤ 0.35Manganese, Mn≤ 0.35Copper, Cu≤ 0.30Aluminum, Al0.20-0.80Carbon, C≤ 0.050Sulfur, S≤ 0.0020Phosphorous, P≤ 0.015Nitrogen, N≤ 0.010Boron, B≤ 0.0060
Physical Properties
The physical properties of Super Alloy Inconel 718 (UNS NO7718) Seamless pipe are given in the following table.PropertiesMetricImperialDensity8.19 g/cm³0.296 lb/in³
Mechanical Properties
The mechanical properties of Super Alloy Inconel 718 (UNS NO7718) Seamless pipe are displayed in the following table.PropertiesMetricImperialTensile strength1120 MPa162000 psiYield strength (at 0.2%)827 MPa120000 psiModulus of elasticity205 GPa29700 ksiPoissons ratio0.2840.284Elongation at break31%31%Hardness, Rockwell C2424
Thermal Properties
The thermal properties of Super Alloy Inconel 718 (UNS NO7718) Seamless pipe are displayed in the following table.PropertiesMetricImperialThermal expansion co-efficient (at 21-93ºC/69.8-199ºF, mean; annealed and aged)12.5 µm/m°C6.750 µin/in°FThermal conductivity11.1 W/mK77 BTU in/hr.ft².°F
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