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An Assessment of Subsurface Residual Stress Analysis in SLM Ti-6Al-4V
Open AccessFeature PaperArticle

Challenges in Additive Manufacturing of Space Parts: Powder Feedstock Cross-Contamination and Its Impact on End Products

1
ESTEC, European Space Agency, 2200 AG Noordwijk, The Netherlands
2
Politecnico di Milano, Via La Masa 1, 20156 Milan, Italy
*
Author to whom correspondence should be addressed.
Academic Editors: Guillermo Requena and Maryam Tabrizian
Materials 2017, 10(5), 522; https://doi.org/10.3390/ma10050522
Received: 30 November 2016 / Revised: 4 May 2017 / Accepted: 8 May 2017 / Published: 12 May 2017
(This article belongs to the Special Issue Metals for Additive Manufacturing)
This work studies the tensile properties of Ti-6Al-4V samples produced by laser powder bed based Additive Manufacturing (AM), for different build orientations. The results showed high scattering of the yield and tensile strength and low fracture elongation. The subsequent fractographic investigation revealed the presence of tungsten particles on the fracture surface. Hence, its detection and impact on tensile properties of AM Ti-6Al-4V were investigated. X-ray Computed Tomography (X-ray CT) scanning indicated that these inclusions were evenly distributed throughout the samples, however the inclusions area was shown to be larger in the load-bearing plane for the vertical specimens. A microstructural study proved that the mostly spherical tungsten particles were embedded in the fully martensitic Ti-6Al-4V AM material. The particle size distribution, the flowability and the morphology of the powder feedstock were investigated and appeared to be in line with observations from other studies. X-ray CT scanning of the powder however made the high density particles visible, where various techniques, commonly used in the certification of powder feedstock, failed to detect the contaminant. As the detection of cross contamination in the powder feedstock proves to be challenging, the use of only one type of powder per AM equipment is recommended for critical applications such as Space parts. View Full-Text
Keywords: Additive Manufacturing; tensile properties; microstructure; cross contamination; space applications; Ti-6Al-4V Additive Manufacturing; tensile properties; microstructure; cross contamination; space applications; Ti-6Al-4V
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MDPI and ACS Style

Brandão, A.D.; Gerard, R.; Gumpinger, J.; Beretta, S.; Makaya, A.; Pambaguian, L.; Ghidini, T. Challenges in Additive Manufacturing of Space Parts: Powder Feedstock Cross-Contamination and Its Impact on End Products. Materials 2017, 10, 522.

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