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

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 695; pp. 6 - 13
• Main Authors: Sui, Shang, Chen, Jing, Fan, Enxiang, Yang, Haiou, Lin, Xin, Huang, Weidong
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 17.05.2017; Elsevier BV
• 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; High-cycle fatigue behavior; Laves phases; Inconel 718; Laser additive manufacturing
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2017.03.098

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.