TITLE:
The Effect of Pre-Thermal and -Load Conditions on IN-718 High Temperature Fatigue Life
AUTHORS:
Paulina E. De La Torre, Alberto W. Mello
KEYWORDS:
Metal Fatigue, Ni-Based Superalloys, Cube Slip, Microstructure, High Temperature
JOURNAL NAME:
Open Journal of Applied Sciences,
Vol.12 No.3,
March
29,
2022
ABSTRACT: 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.