Abstract

Recent improvements in additive manufacturing (AM) has allowed for the installation of gas turbine guide vanes in live engine trials. Electric Power Research Institute (EPRI) has collaborated with Power Systems Manufacturing (PSM) to evaluate the mechanical properties and microstructure properties of a nickel base superalloy material that was installed in live engine trials after 4,000 hours of testing. Guide vanes were manufacturing using both the conventional casting process and additively manufactured using a selective laser melting process. The additively manufactured guide vane utilized advanced cooling channels to help reduce the overall temperature exposed on the guide vanes in the live engine trials.

Detailed characterization was conducted in the two different guide vanes (one manufactured with AM, the other with traditional casting methods) to estimate the average temperature exposure in both components. This was done by quantification of gamma prime in the hottest regions of the components. Additionally, other secondary precipitates, such as M23C6 and MX carbides were evaluated and compared in the two different components. 

Lastly, uniaxial creep testing was conducted in both the casting and additively manufactured specimens and compared to literature findings in traditional casting material. Early testing has shown that the additive manufactured material shows both a significant reduction in long-term creep rupture strength and ductility when compared to the traditional casting material. The material has been shown to be suitable for static components in lower stress and temperature regions, but additional research is needed before AM parts can be utilized for high temperature and pressure gas turbine components.