The SPS Technologies' cobalt-base AEREX™ 350 alloy has been successfully introduced in a GEAE turbine engine for a stator bolt application. Earlier versions had utilized a nickel-base powder Superalloy, to achieve creep and stress relaxation requirements beyond the capability of Waspaloy. Poor formability of the prior alloy precluded fastener hot-heading operations, necessary to achieve beneficial grain flow patterns and efficient material usage. Consequently, bolt product had been machined from billet and isothermal forgings; the additional operations contributed significantly to product cost and manufacturing lead times. AEREX™ 350 was developed as a fastener alloy that provides an acceptable balance of material behavior and formability, allowing high-rate fastener production using conventional manufacturing methods. The alloy was recognized as a cost-effective material option that satisfied tensile and creep strength requirements for the application. Assessment of sulfidation-type corrosion and relaxation behavior of the referenced alloy and more traditional fastener materials will be presented at conditions to 1300F. Elevated temperature thermal exposure degradation assessment at 1350F for 1000 hours indicates this alloy possesses significant high temperature stability. Properties and microstructure of the AEREX™ 350 alloy will be discussed.

AEREX is a trademark of SPS Technologies