Influence of build orientation on high temperature fatigue crack growth mechanisms in Inconel 718 fabricated by laser powder bed fusion: Effects of temperature and hold time

Abstract

Inconel 718 manufactured by Laser Powder Bed Fusionhas been characterized in terms of the microstructure, effect of post-processing heat treatment, and hence dependence of fatigue crack growth (FCG) on build orientation. Long crack fatigue tests were conductedat different temperatures and frequencies. It was found that at 350 ⁰C (transgranular crack propagation) build orientation had no effect on FCG rates. However,at higher temperatures (time-dependent crack propagation)build orientation had a significant effect on FCG rates.This was primarily related to microstructural differences caused by the printing strategy in grain size distribution, grain shape and grain boundary character.