A286 (UNS S66286) Forged Rings and Flanges: Composition, Heat Treatment, Properties and Aerospace Applications

<h1>A286 (UNS S66286) Forged Rings and Flanges: Composition, Heat Treatment, Properties and Aerospace Applications</h1>

<p><strong>A286 (UNS S66286, AISI 660, W.Nr. 1.4980)</strong> is an iron-nickel-chromium austenitic superalloy that is strengthened by precipitation of the gamma-prime phase. It was developed to combine the strength of a superalloy with the cost and availability advantages of an iron-based system, and today it is a standard material for forged turbine rings, compressor flanges, casing rings and high-temperature fasteners operating up to about 700 °C. This article covers its composition, heat treatment, mechanical properties, standards and the forged ring and flange products supplied for aerospace and industrial programs.</p>

<h2>What Is A286?</h2> <p>A286 is a precipitation-hardening, iron-based superalloy containing approximately 25 % nickel and 15 % chromium, with additions of titanium, molybdenum and a small amount of aluminium. Titanium and aluminium form the gamma-prime (Ni₃(Ti,Al)) precipitate that gives the alloy its high strength after a solution-treatment-and-aging cycle. Its microstructure remains austenitic and stable across its working temperature range, and the alloy retains useful strength from cryogenic temperatures up to roughly 700 °C.</p>

<h2>Chemical Composition (wt. %)</h2> <table> <thead><tr><th>Element</th><th>Content (%)</th></tr></thead> <tbody> <tr><td>Iron (Fe)</td><td>Balance</td></tr> <tr><td>Nickel (Ni)</td><td>24.0 – 27.0</td></tr> <tr><td>Chromium (Cr)</td><td>13.5 – 16.0</td></tr> <tr><td>Titanium (Ti)</td><td>1.90 – 2.35</td></tr> <tr><td>Molybdenum (Mo)</td><td>1.00 – 1.50</td></tr> <tr><td>Manganese (Mn)</td><td>≤ 2.00</td></tr> <tr><td>Silicon (Si)</td><td>≤ 1.00</td></tr> <tr><td>Aluminium (Al)</td><td>≤ 0.35</td></tr> <tr><td>Vanadium (V)</td><td>0.10 – 0.50</td></tr> <tr><td>Carbon (C)</td><td>≤ 0.08</td></tr> <tr><td>Boron (B)</td><td>0.001 – 0.010</td></tr> </tbody> </table>

<h2>Heat Treatment</h2> <p>A286 is supplied in the solution-treated (annealed) condition and is then age-hardened. The standard cycle for forged rings and flanges is:</p> <ul> <li>Solution treatment at 980 °C, oil quench or air cool</li> <li>Aging at 720 °C for 16 hours, air cool</li> </ul> <p>This produces a uniform dispersion of gamma-prime precipitates, giving the optimum combination of strength, ductility and creep resistance. Over-aging must be avoided because it reduces hardness and high-temperature strength.</p>

<h2>Mechanical Properties (aged)</h2> <table> <thead><tr><th>Property</th><th>Typical Value</th></tr></thead> <tbody> <tr><td>Tensile strength (RT)</td><td>≥ 900 MPa</td></tr> <tr><td>Yield strength (0.2 %, RT)</td><td>≥ 590 MPa</td></tr> <tr><td>Elongation (RT)</td><td>≥ 15 %</td></tr> <tr><td>Hardness</td><td>≈ 28 – 36 HRC</td></tr> <tr><td>Density</td><td>7.94 g/cm³</td></tr> <tr><td>Maximum service temperature</td><td>≈ 700 °C</td></tr> </tbody> </table>

<h2>Standards and Specifications</h2> <table> <thead><tr><th>Form</th><th>Standard</th></tr></thead> <tbody> <tr><td>Bar, forging stock and rings</td><td>AMS 5731, AMS 5732, AMS 5726, AMS 5853</td></tr> <tr><td>Bars for fasteners</td><td>ASTM A453 Grade 660</td></tr> <tr><td>Plate and sheet</td><td>AMS 5525, AMS 5858</td></tr> <tr><td>Designation</td><td>UNS S66286, AISI 660, W.Nr. 1.4980, DIN X5NiCrTi26-15</td></tr> </tbody> </table>

<h2>Forged Rings and Flanges: Available Specifications</h2> <p>A286 is supplied as seamless rolled rings and forged flanges produced by upsetting, ring rolling and closed-die forging to maximize grain flow and mechanical properties.</p> <table> <thead><tr><th>Product</th><th>Size Range</th><th>Notes</th></tr></thead> <tbody> <tr><td>Seamless rolled rings</td><td>Outer Ø 200 – 2000 mm</td><td>Rectangular, profiled or stepped sections</td></tr> <tr><td>Forged flanges</td><td>DN 15 – DN 1000</td><td>Weld-neck, blind, slip-on, custom</td></tr> <tr><td>Thickness / height</td><td>20 – 400 mm</td><td>Per drawing</td></tr> <tr><td>Machining</td><td colspan="2">Rough or finish machined, NDT (UT, dye-penetrant) available</td></tr> </tbody> </table>

<h2>Applications</h2> <ul> <li>Gas-turbine and jet-engine turbine discs, wheels and compressor rings</li> <li>Engine casings and high-temperature flanges</li> <li>Supercharger and turbocharger components</li> <li>High-temperature bolts, studs and fasteners for aerospace and power plant</li> <li>Exhaust systems and afterburner hardware</li> <li>Industrial gas-turbine and cryogenic components</li> </ul>

<h2>A286 vs Inconel 718</h2> <table> <thead><tr><th>Alloy</th><th>Base</th><th>Strength</th><th>Service Temp.</th><th>Cost</th></tr></thead> <tbody> <tr><td>A286 (S66286)</td><td>Iron-nickel</td><td>High (≈ 900 MPa UTS)</td><td>≈ 700 °C</td><td>Lower</td></tr> <tr><td>Inconel 718 (N07718)</td><td>Nickel</td><td>Very high (≈ 1240 MPa UTS)</td><td>≈ 650 – 700 °C</td><td>Higher</td></tr> </tbody> </table> <p>A286 is often chosen where its iron-based economy and good 650–700 °C performance are sufficient, while Inconel 718 is selected for higher strength or more demanding fatigue and corrosion requirements.</p>

<h2>Frequently Asked Questions</h2> <p><strong>What is A286 alloy used for?</strong><br>A286 is used for forged turbine rings, compressor flanges, casing components, exhaust hardware and high-temperature fasteners in aerospace and industrial gas turbines.</p> <p><strong>How is A286 heat treated?</strong><br>It is solution treated at about 980 °C, then aged at 720 °C for 16 hours to precipitate the gamma-prime phase and develop full strength.</p> <p><strong>Is A286 weldable?</strong><br>Yes, A286 can be welded by TIG and resistance methods; in the aged condition welding is more difficult and typically performed in the solution-treated state followed by aging.</p> <p><strong>What is the maximum temperature for A286?</strong><br>A286 retains useful strength up to about 700 °C; above this, nickel-based alloys such as Inconel 718 or Waspaloy are preferred.</p>

<h2>Ordering A286 Forged Rings and Flanges</h2> <p>Please provide the standard (e.g. AMS 5731 / ASTM A453 Grade 660), ring or flange dimensions, section profile, heat-treatment condition and NDT requirements. Browse our forged product range at <a href="https://www.hangboalloys.com/products/category/superalloy">superalloy products</a> or contact us through the <a href="https://www.hangboalloys.com/contact">contact page</a>. See also our guide to <a href="https://www.hangboalloys.com/news/kovanye-kolca-iz-nikelevyh-splavov">forged rings in nickel alloys</a>.</p>