Effect of Fatigue Loading Mode on 718 Alloy Fatigue Properties

  • Juraj Belan Department of Materials Engineering, Faculty of Mechanical Engineering, University of Žilina, Univerzitná 8215/1, 01026 Žilina, Slovakia
  • Lenka Kuchariková Department of Materials Engineering, Faculty of Mechanical Engineering, University of Žilina, Univerzitná 8215/1, 01026 Žilina, Slovakia
  • Eva Tillová Department of Materials Engineering, Faculty of Mechanical Engineering, University of Žilina, Univerzitná 8215/1, 01026 Žilina, Slovakia
  • Denisa Závodská Department of Materials Engineering, Faculty of Mechanical Engineering, University of Žilina, Univerzitná 8215/1, 01026 Žilina, Slovakia
  • Mária Chalupová Department of Materials Engineering, Faculty of Mechanical Engineering, University of Žilina, Univerzitná 8215/1, 01026 Žilina, Slovakia

Abstract

In materials science, fatigue is the progressive and localized structural damage that occurs when a material is subjected to cyclic loading. If the loads are above a certain threshold, microscopic cracks will begin to form at the stress concentrators such as the surface, persistent slip bands (PSBs), interfaces of constituents in the case of composites, and grain interfaces in the case of metals. Eventually a crack will reach a critical size, the crack will propagate suddenly, and the structure will fracture. The first works about fatigue phenomenon were published since 1837 and intensively was investigated by Wöhler in 1860. With needs of using the progressive materials such titanium and Ni-base superalloys become more significant to put under the various fatigue loading these sorts of alloys. Presented article deals with how the various condition of loading influenced an IN718 alloy fatigue lifetime especially. The fatigue tests provided on this kind of material was done via low frequency loading and push-pull or rotation-bending stress up to this time. Fatigue tests of experimental material was carried out at two different frequencies, 20 kHz with stress ration R = - 1 (push – pull, σm = 0 MPa) as well as the three-point bending load R ˂ 1 (σom = 526.8 MPa) at low frequency 150 Hz at room temperature. The microstructure characterization and Scanning Electron Microscopy (SEM) fractography analysis of fatigue process were done as well. The main goal of study was analyze obtained data after fatigue test and consider, if the various loading modes have influence on fatigue lifetime (initiation sites, crack propagation character, etc.).

Keywords: Alloy IN718, fatigue loading, S-N curve, SEM fractography analyzes
Published online
2018-05-23
How to Cite
Belan, J., Kuchariková, L., Tillová, E., Závodská, D. and Chalupová, M. “Effect of Fatigue Loading Mode on 718 Alloy Fatigue Properties”, Periodica Polytechnica Transportation Engineering. doi: https://doi.org/10.3311/PPtr.12114.
Section
Articles