Metallurgical Studies on Gas Turbine Blade Materials After a Long Term Service

This paper deals with the changes of tensile, impact, and stress-rupture properties and microstructure of gas turbine blade materials due to long term heating at the temperature of 650 C (1200 F) to 800 C (1470 F) for up to 10,000 hr or due to the service operation at similar temperature range on several occasions in 34,000 hr. The relation between the above changes of the properties and the thermal fatigue strength, and the stress-rupture strength and the fatigue strength at 700 C (1292 F) and 750 C (1382 F) under corrosive environment containing vanadium and/or sulfur were also investigated. The materials involved are several heat resisting alloys such as Inconel 700, Inconel X, S816. Useful information for selection of gas turbine blade materials was obtained.