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Open AccessArticle

Fatigue Behavior of Porous Ti-6Al-4V Made by Laser-Engineered Net Shaping

1
Department of Mechanical and Industrial Engineering, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway
2
Institute for Mechanical Engineering and Materials Technology, University of Applied Sciences of Southern Switzerland, CH-6928 Manno, Switzerland
3
Department of Engineering and Management, University of Padova, 36100 Vicenza, Italy
*
Author to whom correspondence should be addressed.
Materials 2018, 11(2), 284; https://doi.org/10.3390/ma11020284
Received: 12 January 2018 / Revised: 5 February 2018 / Accepted: 10 February 2018 / Published: 12 February 2018
(This article belongs to the Section Structure Analysis and Characterization)
The fatigue behavior and fracture mechanisms of additively manufactured Ti-6Al-4V specimens are investigated in this study. Three sets of testing samples were fabricated for the assessment of fatigue life. The first batch of samples was built by using Laser-Engineered Net Shaping (LENS) technology, a Direct Energy Deposition (DED) method. Internal voids and defects were induced in a second batch of samples by changing LENS machine processing parameters. Fatigue performance of these samples is compared to the wrought Ti-6Al-4V samples. The effects of machine-induced porosity are assessed on mechanical properties and results are presented in the form of SN curves for the three sets of samples. Fracture mechanisms are examined by using Scanning Electron Microscopy (SEM) to characterize the morphological characteristics of the failure surface. Different fracture surface morphologies are observed for porous and non-porous specimens due to the combination of head write speed and laser power. Formation of defects such as pores, unmelted regions, and gas entrapments affect the failure mechanisms in porous specimens. Non-porous specimens exhibit fatigue properties comparable with that of the wrought specimens, but porous specimens are found to show a tremendous reduced fatigue strength. View Full-Text
Keywords: fatigue; Direct Energy Deposition (DED); Laser Engineered Net Shaping (LENS); Ti-6Al-4V; additive manufacturing; porosity fatigue; Direct Energy Deposition (DED); Laser Engineered Net Shaping (LENS); Ti-6Al-4V; additive manufacturing; porosity
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MDPI and ACS Style

Razavi, S.M.J.; Bordonaro, G.G.; Ferro, P.; Torgersen, J.; Berto, F. Fatigue Behavior of Porous Ti-6Al-4V Made by Laser-Engineered Net Shaping. Materials 2018, 11, 284.

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