XCT Analysis of the Defect Distribution and its Effect on the Static and Dynamic Mechanical Properties in Ti-6Al-4V Components Manufactured by Electron Beam Additive Manufacture

UoM administered thesis: Phd

  • Authors:
  • Samuel Tammas-Williams

Abstract

Selective electron beam melting (SEBM) is a promising powder bed Additive Manufacturing technique for near-net-shape manufacture of high-value titanium components. An extensive research program has been carried out to characterise in 3D the size, volume fraction, and spatial distribution of the pores in model samples, using X-ray computed tomography (XCT), and correlate them to the SEBM process variables. The average volume fraction of the pores (97.5 %) where fatigue cracks would initiate based on the relative stress intensity factor of all the pores. In contrast, crack growth was found to be insensitive to porosity, which was attributed to the much higher stress concentration generated by the crack in comparison to the pores. Some crack diversion was associated with the local microstructure, with prior β grain boundaries often coincident with crack diversion.

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Original languageEnglish
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Award date1 Aug 2016