XCT analysis of the influence of melt strategies on defect population in Ti?6Al?4V components manufactured by Selective Electron Beam Melting
By S. Tammas-Williams, Hao Zhao, Fabien Leonard, F. Derguti, Iain Todd, P. Prangnell. 2015
556 citations recorded by the source corpus.
Selective Electron Beam Melting (SEBM) is a promising powder bed Additive Manufacturing technique for near-net-shape manufacture of high-value titanium components. However without post-manufacture HIPing the fatigue life of SEBM parts is currently dominated by the presence of porosity. In this study, the size, volume fraction, and spatial distribution of the pores in model samples have been characterised in 3D, using X-ray Computed Tomography, and correlated to the process variables. The average volume fraction of the pores (< 0.2%) was measured to be lower than that usually observed in competing processes, such as selective laser melting, but a strong relationship was found with the different beam strategies used to contour, and infill by hatching, a part section. The majority of pores were found to be small spherical gas pores, concentrated in the infill hatched region; this was attributed to the lower energy density and less focused beam used in the infill strategy allowing less opportunity for gas bubbles to escape the melt pool. Overall, increasing the energy density or focus of the beam was found to correlate strongly to a reduction in the level of gas porosity. Rarer irregular shaped pores were mostly located in the contour region and have been attributed to a lack of fusion between powder particles.
Subfields: Automotive Engineering, Biomedical Engineering, Mechanical Engineering
View Paper: https://www.semanticscholar.org/paper/93f12460b2075fd68cbf4e5d3a96a50bce89d187
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Citations in the corpus
- Review of in-situ process monitoring and in-situ metrology for metal additive manufacturing (2016, methodology): “[33,36] Entrapped gas pores within the bulk of”
- Metallic microlattice materials: a current state of the art on manufacturing, mechanical properties and applications (2016, background): “processes, and so will be most susceptible to imperfections in the form of inherent microvoids due to the stacking-layered-fused nature of the metal powder [78–85], which introduces some level of anisotropy that is difficult to investigate due to stochastic nature of void distribution.”
- A comparison of fatigue strength sensitivity to defects for materials manufactured by AM or traditional processes (2017, methodology): “In this case, computed tomography scans are the standard control used for the identification of internal defects and the adoption of extreme value concepts is an interesting addition the to state-of-the-art for this topic [31,106,107].”
- Effects of heat treatments on microstructure and properties of Ti-6Al-4V ELI alloy fabricated by electron beam melting (EBM) (2017, unknown): “The beam current during hatching is not directly set by the operator, instead, it is calculated by the EBM control software and varied linearly with the length of the hatch line, such that smaller melt lengths have a lower current [27].”
- Effects of defects on mechanical properties in metal additive manufacturing: A review focusing on X-ray tomography insights (2020, background): “results of keyholemodepores near the end of scan trackswere shown in [81] with electron beam PBF (E-PBF) of Ti6Al4V components.”
- Hot cracking mechanism affecting a non-weldable Ni-based superalloy produced by selective electron Beam Melting (2018, background): “XZ as well as XY cross sections showed no “lack of fusion-type defects”, which correspond to unmelted zones leading to incomplete bonding between successive layers [33].”
- Electron beam melted Ti–6Al–4V: Microstructure, texture and mechanical behavior of the as-built and heat-treated material (2016, background): “As highlighted by other authors [25,26], these non-spherical porosities are a consequence of unoptimized process parameters.”