Failure Analyses of Two Gas Turbine Wheels

The results of the analysis of the catastrophic failures of two high pressure turbine wheels are discussed in this study. Fractographic and metallographic analyses on both the wheel and a set of failed blades of both wheels were performed to determine the possible events that led to failure. Both wheel materials had an austenitic microstructure, while blade materials were different for each case. One blade material is similar to INCONEL 738 nickel-based superalloy, while the other study is a single-crystal with dendritic growth microstructure. Facing two failures with apparently similar characteristics, once fractographic and metallographic analysis were performed, it was proved that failure modes respond to quite different origins in each case. This led to different corrective actions, according to each particular main contributing factor.