The effect of hot Isostatic pressing on microstructure and mechanical properties of nickel based gas turbine blade

Solidification microporosity forms within dendritic space of gas turbine blades at large section in investment casting. Microporosity content more than permissible limit significantly reduces mechanical properties of turbine blades at the service conditions. In these work effects of Hot Isostatic pressing (HIP) followed by standard heat treatment cycle process on microstructural characteristics such as grain boundaries serration, microporosity content and mechanical properties of Ni-base superalloy IN738LC have been investigated by optical, Scanning Electron Microscopy (SEM) and practical experiments. The results of studies have shown that hot isostatic pressing provides more serration at grain boundary and could mostly eliminate or reduce microporosity, was generated during solidification by means of sintering. HIP is able also to improve creep life and ductility but has no effect on yield stress at tensile experiment.