Preventative Metallurgical Failure Evaluation of Free Power Turbine Nozzle of Aero-Derivative Gas Turbine Engine

摘要

A set of free power turbine first stage nozzle guide vanes (NGVs) was investigated with the objective of extending its service life after completing 100,000 operating hours. The investigation covered material microstructure examination, mechanical properties, physical parts visual inspection as well as predicting the formation of deleterious phases. New and removed from service NGVs were used as investigation vehicles with testing specimens taken from the NGV root, 10, 50 and 90% span wise direction. Optical microscopy, scanning electron microscopy and XRD were used in the analysis. The investigation concluded that there were no secondary phases formation due to the operation in the as-removed NGV and Nv for both new and as removed from service NGVs were below the specific superalloy Nv limit.