Creep Analysis of Inconel 718 Aged Superalloy at 675°C

The study of creep has a major importance when materials are submitted to high stress and homologous temperature. Superalloys are designed to operate under high stress, temperature and corrosion environment. Those properties of superalloys are due to high temperature stable matrix, solid solution elements and precipitated particles. This study aims to determine the creep resistance of Inconel 718 aged superalloy obtained through the tests according to ASTM E139-06, at stress range of 510 to 700 MPa and temperature of 675°C. The parameters as the primary creep time (tp), steady-state creep rate (εs), time to rupture (tr) and strain to rupture (εr) are important to evaluate the creep resistance. It used a scanning electron microscope (SEM) to obtain images of the fracture surface of specimens. The images of the fracture surface were investigated in order to relate the temperature of test with the fracture mechanism. The microstructure evolution was analyzed using optical microscope (OM) to determine grain size and precipitated particles dispersion.