High temperature indentation based property measurements of IN-617

Inconel 617 (IN-617) mainly contains nickel (Ni), chromium (Cr), cobalt (Co) and molybdenum (Mo). IN-617 is widely used in applications that require high temperature operation due to its high temperature stability and strength as well as its strong resistance to oxidation and carburization. The current work focuses on the measurement of temperature dependent mechanical properties of IN-617 from room temperature (around 25 °C) up to 800 °C. The properties measured are reduced modulus, elastic modulus, hardness, indentation creep rate, indentation creep exponent, and thermal activation volume. The indentation size effect is analyzed as a function of temperature. Using a combination of optical microscopy and scanning electron microscopy (SEM) imaging, the effect of precipitate distribution and oxidation on the measured properties is found to be negligible beyond a critical indentation depth. The mean hardness value ranged from 3.1 GPa at room temperature to 1.6 GPa at 800 °C. A relation between indentation depth and hardness as a function of temperature change was used to extract strain gradient plasticity associated length scales with values changing from 1.0 μm at room temperature to 1.8 μm at 400 °C and to 1.6 μm at 800 °C.