The High Temperature Stability of IN718 Derivative Alloys

Abstract

The excellent fabricability and adequate heat resistant properties of IN7 18 have accounted for the widespread use of IN7 18 as a turbine engine disk material The jet engine industry is placing new demands for an alloy, however, which exhibits the excellent fabricability and heat resistant properties of IN7 18, but which is not hampered by the alloy's relatively low temperature ceiling (approx. 650C). Ticolloy, based on IN7 18, is an alloy developed through a systematic variation of the Al/l? and (Al+Ti )/Nb atomic ratios. Mechanical property data has been gathered to document the tensile, crack growth, creep/stress rupture, and hydrogen susceptibility behavior of Ticolloy as compared to IN7 18. Ticolloy exhibited improved strength and high temperature stability, however, hydrogen susceptibility and crack growth behavior showed no improvement. Finally, a y" coarsening study has been carried out on a series of four new alloys. These alloys were developed to pursue the limit of the methodology employed to develop Ticolloy. tdeceased