Superalloys used for aerospace fastener require a combination of mechanical strength, notch toughness, elevated temperature capability and corrosion/oxidation resistance.

Mechanical strength requirements might include tensile, shear, fatigue, creep and/or stress rupture strengths, depending on the application demands. Strength requirements have increased as new developments in engine design and other technologies have arisen.

The continual need for greater thrust output and better fuel efficiency has resulted in faster-spinning, hotter-running gas turbine engines. This, in turn, has created the need for alloys that can withstand higher stresses and temperatures, a trend that is expected to continue.

Another critical material property is the ability to resist corrosion at ambient and elevated temperatures, including general corrosion, crevice corrosion, stress corrosion, oxidation and sulfidation. For joints exposed to potentially corrosive environments, the fastener should be galvanically compatible with the joint. That is, the materials used should be relatively close on the galvanic series. If this is not practical, platings or coatings can be applied to the “noble” corrosion resistant fasteners to promote galvanic compatibility with structures assembled from more “active” materials, such as aluminum alloys.

It is important to understand that the properties of a superalloy are not merely the result of its composition. Material processing and fastener manufacturing play roles in achieving the desired combination of properties. Cold working, thermal treatments and the sequence of critical manufacturing operations significantly enhance performance.

Marine, space and medical applications are just a few of the environments that challenge the superalloys . Other applications are...

• Space Shuttle Orbiter & Solid Rocket Motors

• Aircraft Structure & Landing Gears

• Aircraft Gas Turbine Engines

• Gas Turbine Engines for Power Generation

• High-Performance Automotive Engines

• Marine—Ships, Submarines, Naval Aircraft

• Petrochemical Equipment

• Chemical Processing Equipment

• Medical X-Ray Imaging Equipment

• Cryogenic Uses

AEREX 350 is an excellent superalloy invented by sps. The details of this alloy are as follows.

AEREX 350 Basics

As gas turbine engine technology and materials technology advanced hand-inhand, new alloys were developed for blades, vanes, disks and other engine components. Many of these alloys were evaluated as potential fastener materials, but most lacked the unique blend of characteristics required. AEREX 350 became the first alloy in many years developed primarily for fasteners; and, counter to the typical trend, may eventually be used for turbine disk applications. 

AEREX 350 has the highest temperature limit of the three superalloys. This high-strength, corrosion-resistant nickelbased superalloy is suitable for demanding applications up to 1350°F. 

Thermal expansion is also a critical factor in elevated-temperature fastener applications, as all the materials used in the “hot zones” must expand and contract at the same rate to maintain joint reliability. AEREX 350 exhibits a thermal expansion rate comparable to many engine component materials, as shown in the adjoining graph. 

Nominal Composition

Nickel 45%

Cobalt 25%

Chromium 17%

Molybdenum 3%

Titanium 2.2%

Columbium 1.1%

Aluminum 1.1%

Tantalum 4%

Tungsten 2% 

Metallurgical Strengthening Mechanisms

Like MP35N and MP159, this alloy undergoes the MULTIPHASE reaction, but also benefits from two additional strengthening mechanisms. Elements are also added to the chemical composition to cause precipitation of the gamma prime (γ ') phase with higher temperature capability than MP159. Because this alloy is used at even higher temperatures than MP159, elements were added to the chemical composition to also cause the precipitation of eta (η) phase during thermal treatments. This phase contributes to notch toughness at elevated temperatures.

AEREX 350 Properties Profile

• Provides excellent stress rupture performance.

• Capable of being forged and manufactured into complex configurations.

• Combines ambient temperature corrosion resistance with elevated temperature oxidation/sulfidation resistance

• Offers a coefficient of thermal expansion equivalent to that of other nickel-based alloys

• Displays excellent notch toughness and thermal stability

• Can be alternatively-processed to 150 KSI minimum shear strength for ambient temperature applications.

• Coupled with its inherent forgeability, AEREX 350 superalloy is capable of providing the largest diameter, highest shear-strength, corrosion resistant fasteners.

AEREX 350 Corrosion Resistance

AEREX 350 corrosion resistance is comparable to the MP159 alloy. Oxidation, sulfidation and hot salt corrosion resistance are comparable to that of Waspaloy.

AEREX 350 fastener Applications

• Aerospace gas turbines

• Power generating gas turbines

• Aircraft landing gear

If you have any questions or needs, please contact us. Here is our contact information:

Price Inquiry：sales.lily@superalloyparts.com 

Technical Support：eng.daisy@superalloyparts.com 

Quality Control：qc.jason@superalloyparts.com