Keywords
Citation
(1998), "New high-strength alloy for turbine fastener", Aircraft Engineering and Aerospace Technology, Vol. 70 No. 3. https://doi.org/10.1108/aeat.1998.12770cab.035
Publisher
:Emerald Group Publishing Limited
Copyright © 1998, MCB UP Limited
New high-strength alloy for turbine fastener
New high-strength alloy for turbine fastener
Keywords Alloys, Engine fasteners, Gas turbines
Engineers have raised gas turbine efficiencies over the years by developing nickel-based superalloys that can handle higher temperatures and rotating speeds, but it has been more than two decades since an alloy for engine fasteners has been developed to match.
A new alloy developed by SPS Technologies of Jenkintown, Pennsylvania, has demonstrated increased creep strength and stress rupture strength between 1,150° and 1,400°F the critical temperature range in modern gas turbines. Aerex 350 exhibits the highest resistance to creep and stress rupture to 1,350°F of any fastener alloy, said an SPS spokesman.
In addition, the proprietary superalloy features a coefficient of thermal expansion similar to the superalloys it is designed to clamp together in gas turbines. Therefore, the Aerex 350 retains clamping loads as temperatures rise.
The new alloy also provides high fatigue strength, resistance to stress relaxation, high impact strength, corrosion resistance, and excellent thermal stability. Bolt ultimate tensile strength is 200ksi at room temperature and 180 ksi at 1,350°F. Shear strength is 132ksi, and Charpy V-notch impact strength is 45ft.lb at room temperature, Aerex 350 has an elastic modulus of 31.3 million psi; a shear modulus of 12.2 million psi; and a density of 0,311 pounds per cubic inch. As with multiphase alloys, its strength is imparted by a combination of cold working and age hardening.
Turbine manufacturer Rolls-Royce and General Electric are both evaluating the SPS fasteners for use in turbine hot-section joints such as disc and gas-path seal joints.