The thermal processing of turbine engine components is a critical step in the repair and rejuvenation of turbine section hardware to ensure optimal performance and reliability. In the repair process, the thermal process regime must meet the following requirements; improving the weldability of the alloy prior to the repair process (if necessary), returning the microstructure of the alloy to a solutioned state prior to precipitation hardening the alloy, and an aging cycle in order to achieve optimal mechanical properties for the alloy. This paper will focus on the criticality of each step and discuss the typical mechanical properties seen after engine service and the repair process. We will show the importance of these steps and how they will ultimately effect the repair of the hot section component. For almost three decades, gas turbine original equipment manufacturers (OEM’s) have cast high-pressure turbine blades/buckets from In738 Ni-base superalloys. Although significant turbine experience has been gained in the use of this material, little or no standardization of repair heat treatments has been established in the industry. Currently OEM’s and component repair shops utilize a variety of refurbishment heat treatments, all targeted at achieving maximum restoration of mechanical properties and base metal microstructure. This paper also summarizes the results of stress rupture testing of service-run material both before and after six different rejuvenation heat treatments. Microstructures in the service-run and heat-treated conditions are also characterized.

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