Author(s)

Paulina E. De La Torre, Alberto W. Mello^*

Embry-Riddle Aeronautical University, Daytona Beach, USA.

Ni-based superalloys are largely used in the aerospace industry as critical components for turbine engines due to their excellent mechanical properties and fatigue resistance at high temperatures. A hypothesis to explain this atypical characteristic among metals is the presence of a cross-slip mechanism. Previous work on the role of thermal activation on cubic slip has shown strain accommodation in two sets of slip planes, which resembled the activation of {100} cubic slip systems along of the octahedral slip planes {111} in Ni-based superalloys under high strain and temperature, exhibiting a more homogeneous strain distribution and less strain localization. Following those previous literature evaluations of initial conditions that can potentially activate cubic-slip planes and provide the level of accommodation and strain homogenization within the grain, this paper presents some experimental procedures and results of Ni-based superalloy (IN-718) tested at 500°C under operational loading condition, without and after being submitted to an overload and overtemperature. The experiments have shown that a pre-condition of 1% strain at 700°C would increase the fatigue life of the IN-718 at 500°C by four times when compared to pristine tested samples. The present results bring up the potential of improving this material fatigue performance, opening the need to further investigate the microstructure as the precondition is applied.

Metal Fatigue, Ni-Based Superalloys, Cube Slip, Microstructure, High Temperature

De La Torre, P. and Mello, A. (2022) The Effect of Pre-Thermal and -Load Conditions on IN-718 High Temperature Fatigue Life. Open Journal of Applied Sciences, 12, 406-419. doi: 10.4236/ojapps.2022.123028.