When a hot end blade for a gas turbine is designed, several failure criteria must be considered to insure reliability. The criteria include (but are not limited to) creep rupture, low cycle fatigue, high cycle fatigue and creep deflection. This paper will focus on the second stage turbine blade for the GE MS6001 industrial gas turbine. BP Amoco has experienced failure of this blade due to excessive creep deflection.
Creep deflection rate is a function of stress level and metal temperature. A typical approach to reducing creep deflection is to reduce the bulk temperature in the blade. In this paper a design is reviewed that has had the stress redistributed, so that the high temperature regions of the airfoil are at a lower stress level, thereby reducing the creep rate to an acceptable level.