Effects of thermal exposure on high-cycle-fatigue behaviours in Ni-based superalloy GH4169

Abstract

Effects of thermal exposure (TE) on high cycle fatigue (HCF) behaviours in Ni-based superalloy GH4169 have been investigated in this study. GH4169 specimens were thermally exposed at 650°C for 1, 2, 7, 14 and 21 days before fatigue test. These TEs produced eruptions, bulge-like features and pits at surface due to oxidation of carbides/nitrides. Fatigue life was not reduced evidently by TE as compared to the specimens in virgin conditions, indicating the insignificant influence of TE on HCF life. Fracture morphology analysis showed fatigue crack mainly initiated from oxides, crystallographic facets and subsurface inclusions. Although long TE is not necessarily related to crack initiation from oxides, crack initiation from oxides is generally associated with a shorter fatigue life.

The Formation Mechanism of Oxide Inclusions in a High-Aluminum Ni-Based Superalloy during the Vacuum Induction Remelting Process

“…The common non-metallic inclusions in Ni-based superalloys are oxides, sulfides, carbides, etc., whereas oxide inclusions have received extensive attention [8][9][10]. In Ni-based Metals 2024, 14, 654 2 of 11 superalloys, oxide inclusions may seriously affect the safety performance of superalloy components due to the large differences in the elastic modulus, deformation ability, and high temperature-oxidation resistance between the oxide inclusion and the matrix [11,12].…”