TITLE:
Dual-System Activation of Ni-Base Superalloy under High Strain and High Temperature
AUTHORS:
Alexandru Lopazan, Alberto W. Mello
KEYWORDS:
Metal Fatigue, Ni-Based Superalloys, Cube Slip, Microstructure, High Temperature
JOURNAL NAME:
Open Journal of Applied Sciences,
Vol.13 No.12,
December
18,
2023
ABSTRACT: Due to their superior
combination of heat resistance, high temperature corrosion resistance,
toughness and strength, nickel-based superalloys have become of extensive use
in the aerospace industry. This research aims to explain why the fatigue life
of Inconel-718 in preconditioned samples had larger fatigue lives than pristine
samples. The hypothesis is that preconditioning at 700°C and 1.0% strain could
lead to thermal activation of the {100} cubic slip plane alongside the {111}
octahedral slip plane, potentially improving fatigue life. Using SEM and EBSD
imaging, the microstructure of Inconel-718 samples were characterized before
and after preconditioning. The directions of the slip bands that formed
following the preconditioning were determined. The result was that the
existence of both the cubic and octahedral slip systems was confirmed, leading
to the thermal activation hypothesized. The existence of both slip planes was
considered to be the reason behind the improved fatigue life due to better
strain accommodation within the microstructure. It is suggested that focuses
for future research includes conducting in-situ observation of slip
activation and the application of preconditioning as a manufacturing method.