Recovery of Microstructure and Mechanical Properties of Service Run GTD-111 DS Buckets

Abstract

Degradation of microstructure and mechanical properties of a service run GTD-111 DS blade was evaluated. The blade was coated with a CoCrAlY coating (GT-29) and had operated on a GE Model MS 5002 engine for 54,850 hours. To recover the microstructure of the degraded blade, the effect of solution treatment temperature on the microstructure and properties was evaluated. The blanks removed from the airfoil tip section were given a commonly used partial solution treatment 2050°F (1120°C) for GTD-111 and a high temperature solution treatment 2175°F (1190°C) prior to the partial solution and aging treatments. Microstructure and creep test results of these heat treated specimens revealed that the high temperature solution treatment was necessary to recover the microstructure and properties of in-service degraded GTD-111 DS buckets.