An acoustic emission study of anisotropy in additively manufactured Ti-6Al-4V
- 66 Downloads
This investigation applies acoustic emission (AE) to study the microstructural features of additively manufactured (AM) Ti-6AL-4V parts fabricated through direct energy deposition (DED). Microstructural features including anisotropy, porosity, and grain size were tailored by processing parameters such as laser power, powder feed rate, and scan speed. Additionally, rolled and annealed Ti-6Al-4V specimens were used as a baseline. AE features were measured for specimens subjected to cyclic loading via three-point bending tests in two orientations. Higher levels of AE counts and energy were observed in the specimens fabricated with higher laser power while lower levels of AE counts and energy were observed in the specimens fabricated with lower laser power. For AM specimens fabricated with low laser power, the AE features were similar in two different testing orientations where microstructures were columnar for both orientations. However, for AM specimens fabricated with high laser power, the AE were different along different testing orientations, with higher indications being along the growth direction. This may be due to the microstructural anisotropy where AM specimens exhibited columnar grains aligned along the growth direction and a mixed columnar-equiaxed grains in a direction perpendicular to the growth direction. The AE features in the baseline rolled and annealed Ti-6Al-4V were considerably higher than those in AM samples. This may be related to fine recrystallized (α + β) microstructure for rolled and annealed Ti-6Al-4V compared to coarse microstructure in AM samples. The AE observations were further studied by AE waveform analysis.
KeywordsAdditive manufacturing Ti-6Al-4V Columnar microstructure Anisotropy Acoustic emission
Unable to display preview. Download preview PDF.
The authors would like to thank Mr. Jeff Crandall and Dr. Tom Maloney with Connecticut Center for Advanced Manufacturing (CCAT) for their great support and assistance. Special thanks go to Peter Bennet with Western New England University. D.S. Li thanks the financial support from Connecticut State. S.A. Niknam thanks the financial support from Western New England University.
- 1.ISO/ASTM (2015) ISO/ASTM 52900: Additive manufacturing - General principles - TerminologyGoogle Scholar
- 4.Gong X, Anderson T, Chou K (2014) Review on powder - based electron beam additive manufacturing technology. Manuf Rev 1:1–9Google Scholar
- 21.Slotwinski JA, Garboczi EJ, Hebenstreit KM (2014) Porosity measurements and analysis for metal additive manufacturing process control. doi: https://doi.org/10.6028/jres.119.019
- 24.Ono K (2011) Acoustic emission in materials research – a review. J Acoust Emiss 29:284–308Google Scholar
- 25.Miller RK, Hill E V K, Moore PO (eds) (2005) Acoustic emission testing. American society for nondestructive testingGoogle Scholar
- 28.Bohlen J, Dobron P, Meza– Garcia E, Chmelík F, Lukáč P, Letzig D, Kainer KU (2006) The effect of grain size on the deformation behaviour of magnesium alloys investigated by the acoustic emission technique. Adv Eng Mater 8:422–427Google Scholar
- 33.Koester LW, Taheri H, Bigelow TA, Bond LJ, Faierson EJ (2018) In-situ acoustic signature monitoring in additive manufacturing processes. In: AIP Conf. Proc. AIP Publishing LLC , p 020006Google Scholar
- 34.Beattie AG (2013) Acoustic emission non-destructive testing of structures using source location techniquesGoogle Scholar