The influence of Laves phases on the high-cycle fatigue behavior of laser additive manufactured Inconel 718

In this paper, a comparative study of high-cycle fatigue tests (T=650°C, f=110Hz, R=0.1, Kt=1) were carried out with wrought Inconel 718 and LAMed Inconel 718. The results show that the influences of the Laves phases on high-cycle fatigue properties are based on the applied stress amplitudes. At a l...

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Bibliographic Details
Published in:Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2017-05, Vol.695, p.6-13
Main Authors: Sui, Shang, Chen, Jing, Fan, Enxiang, Yang, Haiou, Lin, Xin, Huang, Weidong
Format: Article
Language:English
Subjects:
Additive manufacturing
Crack propagation
Cracks
Fatigue cracks
Fatigue failure
Fatigue life
Fatigue tests
Fracture mechanics
Fragments
High cycle fatigue
High-cycle fatigue behavior
Inconel 718
Laser additive manufacturing
Laves phase
Laves phases
Materials fatigue
Nickel base alloys
Stress propagation
Superalloys
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Summary:In this paper, a comparative study of high-cycle fatigue tests (T=650°C, f=110Hz, R=0.1, Kt=1) were carried out with wrought Inconel 718 and LAMed Inconel 718. The results show that the influences of the Laves phases on high-cycle fatigue properties are based on the applied stress amplitudes. At a low stress amplitude, most of the Laves phases held their original morphologies. The fatigue cracks stopped in front or detoured around them, which means that the unbroken Laves phases play an important role in hindering crack propagation. In this way, the high-cycle fatigue life of LAMed Inconel 718 was superior to that of wrought Inconel 718. However, at a high stress amplitude almost all of the Laves phases in the crack propagation region splintered into smaller fragments, parts of which separated from the austenite matrix. Microscopic holes or cracks were formed at the interface, which provided passages for the fatigue cracks to propagate. In this case, the Laves phases were harmful, leading to the degradation of fatigue performance in LAMed Inconel 718 compared with wrought Inconel 718.
ISSN:0921-5093
1873-4936
DOI:10.1016/j.msea.2017.03.098